European Coatings Journal

Primer 03 | 10 Source: Roman Milert/Fotolia Source: roTeg Source: Otmar Smit/Fotolia Use of resources Using energy a...

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Primer 03 | 10

Source: Roman Milert/Fotolia

Source: roTeg

Source: Otmar Smit/Fotolia

Use of resources Using energy and raw materials efficiently is a global challenge. Not only can it drive down costs but it can also protect the environment. Everywhere, sustainable production methods are on the rise. An important goal here is to make the consumption of resources and energy in production lines even more efficient. Frank Lang, from Willy A. Bachhofen AG, reports on how a thixotropic pigment paste can be ground effectively without dissipating too much energy as heat (page 20). And from page 18 on, experts from the industry discuss the innovations in production technology that they need for improving workflows and cutting costs.

Dr. Sonja Schulte

www.european-coatings.com

ECJ_2010_03_A_Primer.indd 3

It is not always possible to strike a balance between conserving resources and protecting the environment. Antifouling coatings combat organisms that attach themselves to ships’ hulls, increasing the drag on the ships as they ply the oceans. However, the biocides which they contain must not pose a threat to the marine environment. Can this conundrum be resolved? At any rate, antifouling was a key topic at the European Coatings Conference “Marine Coatings II” (page 44).

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03 l 2010

European Coatings J OURNAL

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23.02.2010 08:44:21

Market Watch Industry news Take-over 

Interview Fire retardant coatings

“The environmental profile is gaining more importance”

Dyrup buys Polish paint producer Malfarb

Dr. Adrian Beard, Clariant Produkte (Deutschland) GmbH The market for fire retardant coatings is closely linked to construction activities. Due to the financial downturn and its impact on the construction industry, Dr. Adrian Beard, Head of Marketing and Advocacy Flame Retardants at Clariant, expects a market rebound no sooner than 2012/2013. However, especially in Europe the demand for high-end products will increase. _How will the market for fire retardant coatings develop? For what markets and market segments do you expect a growing demand? Dr. Adrian Beard: The fire retardant coatings market is strongly tied to construction activity for large public buildings as for example airports, shopping centres and office buildings. The current financial crisis has affected most other sectors of the economy including construction. A full recovery in this area will only happen when architects and construction companies have regained access to sufficient funding to invest in new projects and overall economic growth picks up and pulls along the construction sector which traditionally reacts slower than other sectors. We expect this rebound for 2012/2013 rather than on the short term.

Fire retardant coatings are chiefly used in public buildings

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Source: Clariant Produkte (Deutschland) GmbH


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Eventtip: European Coatings Conference: “Fire retardant coatings IV” 3 - 4 June 2010, Berlin, Germany www.european-coatings.com/ events

In the near future the demand for high quality fire retardant coatings will increase, e.g. for longer times of fire resistance. We observe this trend mainly in Europe but also for international projects. _What are the effects of environmental and regulatory issues on fire retardant coatings? To what extent will the market experience benefits or constraints from these regulations? Dr. Adrian Beard: In Europe, the development of dedicated fire tests for fire retardant coatings on steel elements has progressed to its final stages. A continuing issue of regulatory attention is the assurance of high quality of fire retardant coatings by factory controls and on the site of application. The problem is that high quality raw materials can be exchanged against inexpensive but far less efficient materials without an immediately visible or detectable effect - only in case of a fire will the poor performance become evident. Proper application of the coatings, be it on-site or off-site, is a key for their reliability and long term performance. The environmental profile of products like coatings is gaining more and more importance, with a focus on reducing emissions of volatile organic compounds by transitioning to water-based instead from solvent-based systems and the avoidance of chemicals of concern like chlorinated paraffins. (gag)

Malfarb produces paints for the professional market in Eastern Europe Source: Dyrup A/S Dyrup A/S, headquartered in Denmark, has acquired Polish paint producer Malfarb. The Polish company manufactures emulsion paints, undercoats, plasters and adhesives for the professional market in Poland and other countries in Eastern Europe. The paint producer has a production facility and warehouse, which are about 130 km away from the Dyrup-site in Lodz, and generated a total turnover of approximately EUR 10.8 million in 2009 with its 120 employees. The merger of the two companies will be completed in two to three years. www.dyrup.com

 Acquisition Flint Group to buy Torda

Source: Flint Group

Flint Group has signed an agreement to acquire Torda, a manufacturer of printing inks for the packaging markets in Northern Europe, the Balkans and the Middle East with a substantial presence in Eastern Europe. “Torda’s setup, especially in Eastern Europe, the Balkans and the Middle East, ideally complements and expands our network of manufacturing and service facilities into these growth markets,” says Dr. Dirk Aulbert, President of Flint Group’s global Packaging and Narrow Web division. The transaction is expected to close by the end of March 2010. www.flintgrp.com


22.02.2010 13:06:49

Market Watch Industry news

 Pigments

Investment

Schlenk and Grolman expand distribution agreement

Performance coatings 

AkzoNobel invests in UK-site AkzoNobel is investing almost EUR 10 million to further boost the innovative power of the UK site for performance coatings. A fire protection testing laboratory and a polymer lab for powder coatings are being added to the existing R&D infrastructure at the company’s Felling site in north-east England. The investment will help further transform the location into a research hub focused on innovation and the development of new performance coatings technology. Due to be completed early next year, the testing lab will be used by the company’s Marine & Protective Coatings business in its development of fire protection coatings.

AkzoNobel will invest in a testing lab for fire protection coatings Source: International Paint Ltd. The new polymer lab is expected to be completed by the end of the year, the facility will enable researchers to handle and develop new materials and will also include scale-up capability and an application line. www.akzonobel.com

The companies Schlenk Metallic Pigments GmbH and Grolman GmbH & Co. KG have agreed upon an expansion of their business collaboration. The Grolman group will take on responsibility for sales of Schlenk’s aluminum and bronze pigments as to respective market and product segments in Germany, Austria, Switzerland, France, England, Ireland, Benelux, Hungary, Romania, Moldavia, Bulgaria and the region of the former Yugoslavia. www.schlenk.de

 Market study Middle Eastern and African paint industry to grow

Industrial coatings 

HMG Paints to invest in Indian joint venture HMG Paints, the family-owned paints and coatings firm based in Collyhurst/UK, has announced that it will invest in its joint venture to boost capacity. “At present, the company has a production capacity of 100,000 litres per month,” said Titan HMG Paints’ managing director, Ravi Sam. “We shall be investing GBP 1.6 million (GBP 1 = EUR 1.14) in the next two years, to increase capacity three times by 2012. Our sales target is to touch GBP 13.4 million over the next five years.”

Formed last year, Titan HMG Paints India is a joint venture between HMG Paints and, Titan Paints & Chemicals, which is owned by Indian firm LMW Group. The business is based in Coimbatore/India and produces a range of industrial coatings, for protecting plant, machinery and other structures from abrasion, corrosion, weathering and chemical attack. www.hmgpaint.com

Resins 

DSM inaugurates new resins plant in Germany vestment costs amounted to EUR 15 million. The new plant was built at the company’s existing site and allows for further expansions in the future. With the new plant the resins producer reinforces its position in the fast growing and important markets DSM invested about EUR 15 million at its site in Meppen/ such as metal packaging Germany Source: Royal DSM N.V. (can), pre-painted metal (coil), specialty decorative markets, speRoyal DSM N.V. has announced that a cialty adhesives, graphic arts and indusnew plant for the production of wet polytrial wood. esters and other specialty resins in Mepwww.dsm.com pen/Germany has been opened. Total in-

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Split of the Middle Eastern paint market by country, 2009 (volume share in %) Source:Information Research Limited (IRL) In many countries of the Middle Eastern and African paint industry growth of 4-5 % per year until 2014 is projected. According to IRL’s report “A Profile of the Middle Eastern and African Paint Industry”, in some countries the growth rate is considerably higher, as many of these markets have been quite sheltered from the effects of the global economic crisis. This third-edition volume offers a fresh look mainly at the decorative paint markets in 18 countries which is especially valuable at a time when more companies are concentrating their efforts on these growth markets at the expense of the more mature markets of the west. The report includes a market forecast based on estimates of the decorative and overall market sizes until 2014. www.informationresearch.co.uk


22.02.2010 13:06:53

ECJ_

Market Watch Industry news

 Chemicals distribution

Interview Pigments

Univar to acquire Quaron

“Strong signs of recovery” Henk Loonstra, Trust Chem Europe B.V. Trust Chem has recently opened a warehouse for organic pigments in the Netherlands. For Henk Loonstra, Director at Trust Chem Europe B.V., the location provides advantageous conditions to access the European market. He further expects a growing market for eco-friendly pigments. _Why did your company choose the Netherlands as location? Will you expand to other countries in Europe? Henk Loonstra: The Trust Chem Europe headquarters are based in the eastern part of the Netherlands, at a 20 minutes driving distance from Germany, the main market for organic pigments in Europe. We combine the logistic facilities of the number one port of Europe, Rotterdam, with being close to our customers. At this very moment we are completing our distribution network in each and every country in Europe.

is that the manufacturing of organic pigments is moving more and more to Asia. We expect this trend to continue at an increased speed. At the same time we are aware of Western standards for quality consistency of production and quality assurance of every single batch supplied to the end user. The growth of the pigment market will be in environmental friendly high performance pigments. Already today, with our four production sites, Trust Chem is the largest Asian manufacturer of organic pigments supplying to the European markets. We have invested heavily in R&D and production of a full range of high performance pigments. (gag)

Jotun expects massive growth in sales this year

Source: Trust Chem

 Capacity expansion Kuraray commences new PVB resin production line in Europe

Kuraray Europe GmbH increased the annual capacity of PVB resins by 10,000 tons Source: Kuraray Europe GmbH

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03 l 2010

Univar, a global chemical distributor, has signed an agreement to acquire the Quaron Group, a distributor of chemicals in Belgium, France and the Netherlands. “Quaron is a perfect fit for Univar,” said John van Osch, President, Univar EMEA. “Its efficient commodity network complements our industry focused product ranges in Benelux and France, and its site in the Netherlands will create new business and operational opportunities for us.” The acquisition is subject to regulatory approval by the EU Commission. www.univareurope.com

 Asia

_How do you rate the pigment market in Europe? To what extent will the market show growth in the near future? Henk Loonstra: We see strong signs of recovery of the European industry. Fact

Univar operates from 56 distribution locations in 20 countries across Europe Source: Univar Europe

Japanese Company Kuraray Co., Ltd has executed production capacity expansion of PVB (polyvinyl butyral) resin by constructing one new line at its European subsidiary, Kuraray Europe GmbH (KEG). The company invested EUR 26 million in the capacity expansion project. KEG, located in Frankfurt am Main/Germany, has finished trial operation, and just started commercial production. The total annual capacity of PVB resin has been increased by 10,000 tons to 39,000 tons. Among other applications PVB resin is used as a binder in paint, printing ink, and ceramics. www.kuraray.eu

Paint producer PT Jotun Indonesia, which is part of the Norwegian Jotun Group, is optimistic that it will be able to increase its sales by about 40 % to at least IDR 550 billion (IDR 1 = EUR 0.00008) this year thanks to a surge in the country’s demand for paint. The company also plans to increase its production output to 14 million liters to meet the growing demand, said Jotun Indonesia president director Bjorn Abraham Bache. www.jotun.com

 Binders Wacker boosts supply for surface coating resins Wacker, a Munich/Germany-based chemical company, is boosting delivery capacity for surface coating resins. Starting in the first quarter 2011, the amount of “VINNOL H 15” available for delivery will rise substantially by more than 50 %. The resins are used mainly as binders for industrial and packaging coatings, printing inks and adhesives. www.wacker.com


22.02.2010 13:07:00

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Market Watch Distribution

Source: schlomaster/SXC

Prenuptials between suppliers and distributors Transparency and understanding: building successful partnerships

* Contact: Keith Dobell PolYnfo Associates Ltd. T+44 1604 881513 Keith.Dobell@btconnect. com

Keith Dobell Divorce: a costly enough business in one’s personal life: but, in business, not only costly – potentially damaging. Choosing the right partner is paramount, with all the stakeholders included in reaching this decision. Trust, openness, loyalty & faithfulness are undoubted strengths of a good relationship. But having an understanding of the partner’s history, open & hidden agenda, will mean going in with eyes open.

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hether formalised by contract or just a gentlemen’s agreement – selling binders, pigments & fillers, additives into coatings and allied sectors, benefits from that philosophy.

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Doing business together Industrial marriages breakdown for many reasons: infidelity, cruelty, abuse. Partners making separation plans have exit strategies, lined up replacement shoe-in partners and simply waiting for the “off”. For the unsuspecting partner, the traumas of repairing their market after the event puts them at a serious, costly disadvantage: so careful selection at the outset is paramount. In the coatings sector, many highly successful supplier/ distributor partnerships exist and this article is not suggesting otherwise. However, pitfalls of doing business together are highlighted, to make each party think how to achieve stable & secure relationships.


22.02.2010 13:06:00

Market Watch Distribution Influence of industry consolidation Industry consolidation is a major factor leading to enforced breakdowns. Consolidation or other ownership change (MBOs), changes in company structure & strategy, resulting potential conflicts of interest and inevitable decisions to favour established/approved corporate partner routes to market, have a big impact on any previous relationships. Suppliers switch distributors for various reasons. Distributors switch suppliers because more lucrative options present themselves or through suppliers’ pressure over conflicts of interest after an acquisition disturb the previous equilibrium.

Direct selling or via distributors? One of the first of supplier’s decisions to be taken is how far to outsource sales activities – fully/partially, globally/ regionally/nationally. As suppliers downsize sales resource, decision on routes-to-market swing: continue direct selling or use a distributor? Distributors must cut their cloth to meet means with sales resource refocused concentrating on main contributors, keeping market share or growing in volumes/margin. Choice on distributor is between using major multinationals or local specialists: each has strengths and weaknesses; e.g. technical competence, infrastructure, flexibility.

More info on markets: www.europeancoatings.com/ markets

Consider benefits and pitfalls An early decision for the supplier is how to service customers: sell direct, use a distributor, plus take out costs in the process. The stakeholders in any supplier/distributor partnership all have to consider the benefits and pitfalls with care. Understanding the open agenda and possibly pre-empting any hidden one, is key in choosing partners. Consider stakeholders and channel their input within the decision process. Firstly, who are they: every department and all worth consulting within decision process. All departments are affected by a new commercial partnership: impact on some is less but the support from others may be an additional burden and change working practices. Plans cannot be disclosed to all within the company, but stakeholders’ positions have to be weighed up. Inadequacies in the arrangements often only show as transactions commence and strain shows: putting things right after that can be painful.

Customers need to feel involved Customers: what’s it to do with them? Customers’ position and perceptions must never be overlooked and need carefully consideration. After all, they are the very essence of sales. Why cause a rift opening doors to competitors who will exploit every point to win new business? Customers benefit considerably by smoothing out of any previous supply problems but they may feel aggrieved by the changes, believing they are paying a middleman’s margin. And they dislike losing that direct supplier contact. The customer is the common link and needs to feel involved; not abandoned. Inform them at every step once details are available but poll them during screening phases.



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22.02.2010 13:06:01

Market Watch Distribution

Figure 1: Consider stakeholders and channel their input within the decision process

Making it work A CEO’s main interest is showing the owners/stockholders the business is performing and making the right strategic decisions. Far from the day-to-day workings of a new partnership, a CEO probably sees things only when they show as a star performer or once things go wrong. Initial decisions involve input from higher levels but the final choice is at operational level, rubber-stamped from above. Business Managers have the burden of making it work at the distributor; Distribution Managers have the job from the supplier’s side. Both need the full support to underpin the initiative. Selection is made on best-fit basis, perfect partners are rarely found: commodities and specialities need very different handling. Major distributors want Hand-Over-Business (HOB), are best suited to selling volume products and unlikely to give time to developing sales from scratch: unless there is a terrific case and very rapid return to justify it. Conversely, a specialist

distributor does just that – develops an interest in the product and its concepts. HOB is always welcome but for a supplier entering a new sector, it simply is not there to transfer. Suppliers lose control of their market by delegating sales contact. Removal of the direct customer interface makes it harder to register & respond to shifts in the market/ trends. Suppliers classify accounts, diverting many to distributors. Initial business transfer looks good, volumes to a central point, satisfying operations & logistics criteria. Sales to the distributor appear to show growth as territories are extended; but stagnate. A supplier then wonders where the growth has gone, direct accounts get poached: and there can even be substitution made at the product level, for margin gains or, worse – a replacement/alternative source introduced. But suppliers need to consider the distributors: they suffer when suppliers take the foot off the pedal, leaving everything to the new organisation because the supplier has downsized in the wrong areas. Communications break down, service levels drop, lead-times extend and other factors hit the supply chain. Before long, the distributor has no stock, works hand-to-mouth on delayed orders, already exacerbated by reduced working capital initiatives. Suppliers’ production scheduling then comes under pressure to get product in place. HOB (always welcomed) until it is fully understood: it can be a two-edged sword! Although there are useful pieces of business, others prove pure fiction, not entirely profitable or downright risky. Financial Departments are burdened with poor credit risk accounts. Sales Departments halt sales, due to customer’s late payments. Conversely, supplier’s CFOs will be over the moon at losing all those slow payers. HOB (essential for the majors) margins will be the measurement by which the business is judged. Margins will be adjusted to give desired returns – but adding distributors’ margins may kill the business. Ratchet effect pricing is another problem – costs and currency rates used to justify increases rarely reverse for the customer. But as soon as the rate climbs again increases pile on again. Customers have long memories (computers!): purchasing managers are too professional to let that slip through the net. But it still dents customer’s perceptions as product price increases reflect ultimately on the supplier, regardless of who set the ball rolling.

Realism as a key to success

Figure 2: Important decision: Direct selling or via distributors?

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Frequently suppliers’ aspirations/expectations exceed reality. Ambitious targets are set in the motivational process for both parties but over-egging potential must be avoided. Honesty allows distributors to allocate resource sensibly and achieve targets rather than fail to perform. Realism is the key to success here. Some distributors are past masters at putting a front-man in place for meetings outlining a wonderful structure/ boundless resource: but is that real? Suppliers need to ask themselves questions that get behind that façade of “all things to all men”. »»Is resource real? »»Is resource really competent enough to handle the product?


22.02.2010 13:06:02

KREIS-BASKET-MILL®

Market Watch Distribution »»Has it the in-depth technical ability required to develop sales? »»Who really owns that resource? »»What else do they have on their plates? »»What are their real priorities? »»What will really get done, by whom, when? »»How much time will be devoted after the initial thrust? The sales team shown may not truly represent the infrastructure and that resource can be under the control of another sector manager with very different objectives. Key volume suppliers already take up the bulk of the specialists’ time. Account Managers under increasing pressure to achieve call rates, fall into the pattern of offering easiest sell products (commodities). Technical/detailed talk takes time and development times are unacceptably long. Major distributors’ key suppliers demanding time: minor products pale into insignificance, getting a mention before the close of meetings: and that mention decreases at subsequent meetings. Specialist distributors, thrive on having many strings to their bow - solutions to their customers’ problems. Their strength is in having a highly adaptable technical sales force.

Avoiding mixed batch deliveries Multi-site distributors cover regional/national/local requirements for volume products but specialities may need special treatment (temperature-controlled storage, shelf-life control). How does the product look when it is delivered in a dirty, dishevelled state? Is quality controls geared for certificates of analysis, monitoring expiry dates? Warehouses may not consistently practice FIFO (First in, first out) or batch control, simply sending out product nearest to hand, resulting in a hotchpotch of batches in stock. Customers hate mixed batch deliveries: another black mark against the product and supplier.

Multiple distributorships In their quest for new business, new market sectors or geographical regions, suppliers can muddy the waters by appointing more than one distributor. Multiple distributorships are a nightmare. Policing multi-distributors effectively proves impossible - there are always grey areas. The mix of distributors poach each other’s business, confuse customers, destabilise local pricing and stock control issues. If suppliers must appoint more extra distributors, they need to consider the outcome and separate them by several degrees.

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Transparency, essentially part of any successful partnership: although care has to be taken over what is disclosed, without full, updated understanding of where the market is going and its needs, partnerships are doomed. Eventually dissatisfaction creeps in, mistrust builds, and getting relationships back on track takes an enormous commitment and effort by all parties. With so many factors in creating and maintaining successful supplier/distributor partnerships, hopefully this article has served to make partners consider each other’s concerns in a different light.

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ECJ 2006 Kreis-Basket-Mill

Consider a partner’s concerns

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DISPERGIER- UND FEINMAHLTECHNIK www.european-coatings.com 03 l 2010 European Coatings J OURNAL


22.02.2010 13:06:02

Associations EuPIA

Proactive on food packaging inks EuPIA issues two core guidance documents At present, on European level detailed legal provisions exist for packaging material made from plastics; as yet there is no specific legislation for other packaging materials, such as for example paper and board.

F

ood packaging must be manufactured such that it does not transfer its constituents to the packed foodstuffs in quantities which could endanger human health, cause an unacceptable change in the composition of the food, or inadvertently affect foodstuffs in terms of odour and taste. These general requirements are laid down in the European Framework Regulation (EC) No 1935/2004 on materials and articles intended to come into contact with food. The GMP Regulation (EC) No 2023/2006 lays down rules on good manufacturing practice for materials and articles intended to come into contact with food. It specifies that quality assurance and control systems are to be established and implemented. Food packaging is normally printed to provide information to the final consumer (concerning contents, food ingredients and nutrition facts), as well as for decorative and protective reasons. There are exceptional instances where printing inks are applied on the inner side of the packaging or on inserts and intentionally have direct food contact. These cases are only negligible in volume. The definition of food packaging inks also includes primers, lacquers and overprint varnishes applied by a printing and/ or coating process, such as flexography, gravure, letterpress, offset, screen, non-impact printing or roller coating.

Legal compliance: Guidelines assist As with non-plastic packaging material, there is not yet any specific EU legislation concerning printing inks for food packaging, with the exception of Directive 2007/42/ EC relating to materials and articles made of regenerated cellulose film, which states that the printed surface of regenerated cellulose film must not come into contact with food. Currently, the trade associations are required to provide assistance to their member companies to enable them to contribute their share to the legal compliance of the final packaging. EuPIA issued two core guidance documents for its member companies:

Dr. Martin Kanert, Executive Manager EuPIA

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»»EuPIA Guideline on Printing Inks applied to the non-food contact surface of food packaging materials and articles: EuPIA member companies are committed to following this guideline, which sets out in full the responsibilities of the ink manufacturers within the


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Source: H. Hoppe/Pixelio

packaging chain. Food packaging inks are formulated and manufactured taking into account many individual and varying parameters relating to the substrate, application and end-use. They are designed to minimise the potential for transfer of ink components into food, whilst meeting the end use requirements. Although the Guideline already includes a scheme for the careful selection of raw materials, EuPIA additionally made publicly available a list of all the raw materials used in the manufacture of food packaging inks, include all data necessary to enhance consumer protection and product safety. The list is intended to become a reference for competent authorities, too. The as yet incomplete inventory list is accessible via www.eupia.org. »»Good Manufacturing Practices for the Production of Packaging Inks formulated for use on the non-foodcontact surfaces of food packaging and articles intended to come into contact with food: Printing inks intended for use on food packaging are in the scope of the aforementioned GMP Regulation. The EuPIA GMP details the requirements of the GMP Regulation for the printing ink industry. The Annex to the Regulation introduces detailed rules, which relate to processes involving the application of printing inks to the non-food contact side of a material or article. In order to meet the requirements stipulated in the Annex, there needs to be cooperation between the ink manufacturer and the rest of the supply chain, since the ink manufacturers do not have an independent responsibility. However, those who actually apply the ink or coating are ultimately responsible for compliance with the Annex of the Regulation.

Proactive: Public inventory list Recently Switzerland – as the first country in the world – had amended its Consumer Goods Ordinance with provisions specific to food packaging inks. The core element of the new regulation is a list of “permitted substances”, identifying the only substances which may be used in food packaging inks. This list has been established in cooperation with EuPIA, which was able to make use of the efforts already undertaken for its own EuPIA public inventory list. The Swiss list will become applicable as from 1 April 2010. The lesson learnt: Being proactive pays off. Info: Documents are available at www.eupia.org.

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22.02.2010 13:10:03

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Expert Primer Voices

Production technology

Great events often follow little causes Laboratorial amounts transferred to large-scale products Coating manufacturing means to maintain the product performance obtained in R&D status. Therefore physical forces during production are carefully adapted from lab to large-scale production. Gerard Noordhuis, Zandleven Coatings, and Mark Traber, Bühler AG, also show how to decrease costs by modulating production workflows.

“During production process, modifications are allowed as long as they do not affect the final properties.”

1

How do you assure the functionality of a product that has been transferred from R&D into large-scale production?

2claim What innovation demands do you for production technology in order to

Gerard Noordhuis Technical Manager Zandleven Coatings B.V. Leeuwarden, The Netherlands

improve workflows or to decrease costs?

1

All main parameters and test results must be obtained when a project transfers from R&D phase into large scale production. In order to ensure that it is important that the production process will be carried out similar to the lab process. For sure there is a different scale (size), but those standard differences have to be taken into account. During the production process, modifications are allowed as long as they do not affect the final properties. When the production batch is completed, the final products will be sampled and tested compared to the lab sample. Modifications during production process will be examined carefully. The test procedure includes chemical, mechanical and physical properties. Based on mentioned properties, the recipe will be finalised or adjusted to the obtained production result. In some cases the production process has to be optimised. Lab personnel and production operators are responsible for this success. Excluding luck etc, the pilot batch has to be produced at least three times, to ensure that all production parameters are clear.

2

In order to improve workflows and finally decrease costs, in other words logistic be

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nefits, our approach is based on products and equipment. Product: when a resin has a high viscosity it takes a lot of time to unload the truck (phase 1) and to fill production tanks (phase 2). Modified resins or other raw materials with initial high viscosity mixed with significant lower viscosity will effect production time and costs. This is just one example in order to improve the workflow. When those product modifications are not possible, production modification is required. First of all it is necessary to check the actual status of the available production units and how they can be modified in the easiest way in order to gain some logistic benefits (shortening the production process) New production units are always optional. Phase 1 and 2 are based on raw materials and the production of intermediates. Phase 3 is in-can tinting and filling, automation with minimum input of labour. At this moment we work with a filling during tinting machine but there are still similar processes which do require some labour. All modification of existing production units or the purchase of new equipment, must meet the secondary requirements, meaning they must be environmental and labour friendly.

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23.02.2010 09:29:22

Primer Voices Expert Production technology

“Continuous processes allow smooth flow from the delivery of the raw materials to the shipping of the final goods.”

Mark Traber Product Manager, Grinding & Dispersion Technologies Bühler AG Uzwil, Switzerland

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One of the most important requirements of the demanding coating industry is the ability to scale-up successful product deve lopments to an industrial dimension in order to assure commercial benefit. The successful scale-up process is based on constant impact of physical forces towards the product, in our case mainly dispersions. The most important parameters are process temperature, shear rate and product pressure. These physical parameters shall change in a limited window only whether using a lab scale production unit for R&D or a high capacity production plant. By designing process equipment it is essential to consider complete type series. Successful production units in many cases are based on corresponding lab units. The interactive mechanical and procedural influences are developed and proved in our application labs and pilot plants and then transferred to the drawing board of design engineers.

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material handling, quality checks or cleaning are replaced by automated dosing, weighing and flushing systems. In order to profit consequently on the advantages of automated, continuous systems close collaboration between the plant operator and us is necessary. By standardising products or designing concepts based on intermediate goods the production capacity of a plant can be increased which again improves the productivity and reduces the operation costs.

Logistic Optimization of Chemical Production Processes Sebastian Engell www.wiley.com

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Besides product related requirements like productivity and constant product qua lity properties, the most important driver for complete production solutions is to reduce costs. That is why we focus on continuous production processes. Continuous processes are predestined in order to optimise and improve workflows. Compared to traditional batch processes, continuous processes allow smooth flow from the delivery of the raw materials to the shipping of the final goods. Time consuming manual operations like raw


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Source: Bühler AG

23.02.2010 09:29:23

Technical Paper Grinding technology

Source: Frank Muckenheim

Keep the hose short and the beads small! Grinding a thixotropic material

* Corresponding Author: Frank Lang Willy A. Bachhofen AG Switzerland T +41 61 6867 288 [email protected]

Frank Lang The non-Newtonian properties of many materials that need to be ground make the choice of throughput level and bead size critical. Furthermore, the time spent in areas of low shear rate, such as pipes and hoses, can lead to a viscosity rise and should be kept to a minimum.

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Video interviews on production technology: www. european-coatings. com/videos

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any of the materials that are ground in stirred-media mills show non-ideal flow behaviour. Paints, varnishes and pigment pastes can be numbered among them. They frequently contain agglomerates and wrinkled polymer structures. These polymers, including polyelectrolytes, are often used for the wetting of the particles in a suspension and as dispersants. The solid content is in many cases higher than 40 percent by weight; this means that the probability of agglomeration is quite high, because of the low amount of liquid that is available for the wetting of the particles. These factors have an influence on the flow behaviour as does the increase in viscosity that occurs during grinding due to the increase in solid surface area. With decreasing particle size, the adhesive forces increase; thus


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further supporting the reagglomeration processes. A high solid content is desirable for processes such as drying, when wet grinding is used, because less liquid has to be evaporated and, as a result, the energy costs are lower. High shear stress is frequently needed at the beginning of the grinding process to make the material flow; this is often made necessary by the presence of the structures like agglomerates and wrinkled polymers as mentioned above. Therefore, such materials require a careful choice of equipment as well as process parameters. Beside the specific energy input and the bead size, the throughput and optimal operation of the mill play a major role in achieving the required fineness. Strong shear forces should be maintained after the start-up, in order to attain a reasonable degree of grinding and to keep the viscosity under control. This can be achieved by adjusting the tip speed in the mill or by using a gear pump and high stirrer speeds to shear the product before it enters the mill. Short hoses and pipes should be used, in order to reduce the opportunities for the above-mentioned structures , to reform and the viscosity to rise. In the following description of the grinding of a thixotropic pigment paste, the milling parameters are addressed step by step.


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Technical Paper Grinding technology Figure 1: Experimental setup

Figure 2: Particle size D90 as a function of the specific energy input

“The Rheology Handbook” Thomas Mezger www.europeancoatings.com/books

Recirculation mode as experimental set-up All experiments were carried out in the recirculation mode, as shown in Figure 1. The throughput was measured online, together with the density and the viscosity of the product going into the mill, using the instrument

Results at a glance Experiments have shown that the throughput is a key parameter in the grinding of water-based, thixotropic pigment paste with non-ideal flow behaviour. The effect is less at lower bead sizes. When the raw-material particle size is already quite fine, the adhesive forces between the particles are quite large; the problem is mainly one of dispersion rather than “true grinding”. If there is a dispersion problem, the viscosity has a major influence on the particle sizes that can be achieved, because of agglomeration. This leads to an increase in the viscosity and energy otherwise used for grinding is needed to displace the liquid. Beyond a certain point, an additional input of specific energy leads to reagglomeration and most of the energy is converted directly into heat.

American Coatings Conference 12-14 April 2010 Charlotte/USA www.americancoatings.com

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After grinding, the viscosity is higher at all shear rates and the thixotropic behaviour is even more obvious, when compared to the raw material. The influence of the throughput shows that areas of lower shear rate should be kept as small as possible. Therefore, it is recommended to use short hoses and pipes to reduce agglomerate formation and a subsequent increase in the viscosity.



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Promass 83I25, which measures the Coriolis force. Shear stress was produced with a gear pump. The particle size analysis was carried out using the principle of light scattering. The instrument used has a red laser for particles that are larger than 1 µm and a blue laser to measure particles in the range below 1 µm. 90 % of all particles in the product had a particle size below 1 µm before grinding, which means that the dispersion of the particles plays a larger role than “true grinding”. In order to check the flow behaviour of the product offline, viscosities were measured offline using a rotational viscometer. The pigment paste was run on a middle-sized production mill. The applied parameters were the following: »»Flow rate 500 kg/h and 4000 kg/h »»Tip speed: 10.9 m/s »»Bead size: 0.8 mm and afterwards 0.3 mm »»Grinding time: 4 hours with both bead sizes »»Batch size: 100 kg

Various particle sizes grinded The beads used in the experiments had diameters of 0.8 mm and 0.3 mm. Figure 2 shows the particle size D90 as a function of the specific energy input with different bead sizes. When milling is carried out with 0.8 mm beads, practically no grinding takes place up to a specific energy input of 500 kJ/kg. Between 500 – 700 kJ/kg, the particle size actually increases briefly, as mainly deagglomeration and wetting of the particles are taking place. Between 700 kJ/kg and 1700 kJ/kg, the particle size decreases to less than 700 nm. In this area, some “true grinding” is probably taking place. Beyond 1700 kJ/kg, the particle size hardly decreases any further. This is probably a sign of reagglomeration, due to the increase in the particle surface area caused by “true grinding”. The result is that the surface area requires more liquid for the wetting of the particles. After the grinding with a bead size of 0.8 mm, the diameter was changed to 0.3 mm. At this smaller bead diameter, a high level of grinding occurs up to a specific energy input of 250 kJ/kg giving a particle size below 500nm. However, beyond 1500 kJ/kg, the measured particle size do not decrease any further and even rose slightly. This is a clear indication of reaglommeration.


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Technical Paper Grinding technology Viscosity and flow behaviour In order better to understand the grinding and dispersing processes, a closer look needs to be taken at the viscosity and the flow behaviour. Figure 3 shows the flow curve, with the shear stress t and the viscosity h of the raw material, as a function of the shear rate g, at a temperature of 30 °C. The flow curve and the viscosity curve of the material, after grinding for four hours, are shown in Figure 4. The shear rate was first increased, kept constant at a value of 1000 s-1 for 30 s, and then decreased back to zero. At the beginning, high shear stress is required to make the product flow; the product behaves more like a solid than a liquid and the viscosity tends towards infinity. When the shear rate reaches 1000 s-1, the viscosity of the raw material goes down to 0.688 Pas. The viscosity of the ground product decreases to 0.74 Pas. Figure 3: Flow curve and viscosity curve of the raw material

Dispersion influences grinding Furthermore, the product clearly shows thixotropic behaviour, because the viscosity is lower during the decrease in shear rate than as it increases. This occurs at all shear-rate values. This behaviour is probably due to the disintegration of agglomerates which then take some time to reform after the shear stress is decreased. Therefore, this is a further indication that the grinding problem at hand is primarily one of dispersion. At the beginning of the grinding process, the primary particles have to be wetted and dispersed, in order to break up the agglomerates. The breakage of primary particles down to a smaller size probably only occurs after the dispersion has been almost completed. Once a finer particle size is reached, the adhesive forces between the particles also increase, thus leading to reagglomeration, as shown in Figure 2. Since the finer particles have a larger specific surface area, the viscosity increases for all shear rates, which can be seen in Figure 4.

Figure 4: Flow curve and viscosity curve after four hours of grinding

Figure 5: Flow and viscosity curves with higher shear rates after four hours of grinding

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Interplay of shear rate and throughput Thixotropic behaviour becomes more obvious at higher shear rates as shown in Figure 5, with a maximal shear rate of 3000 s-1 instead of 1000 s-1. When the shear rate arrives at to 3000 s-1, the viscosity is 0.419 Pas. When, after 30 s at 3000 s-1 the shear rate decreases, the viscosity goes down to a value of 0.096 Pas. This means that the longer the material is sheared, the less time remains to reform structures such as agglomerates and, therefore, the viscosity is lower. It can be concluded that in practice it is desirable to have short hoses and pipes, in order to minimize the time spent in areas with low shear stress, where the viscosity can increase again. Figure 6 shows the influence of the throughput on the viscosity. At a throughput of 550 kg/h, the time spent in areas with low shear stress is quite long and the viscosity, measured on the flow meter before the mill, is over 1400 mPas. Above a certain flow rate, the pigment paste is constantly sheared in the gear pump as well as in the mill. The minimum shear stress, i.e. that required to surpass the flow limit, is practically always given. As a result, the viscosity decreases drastically. The product particles are pumped through the mill more often; thus,


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Technical Paper Grinding technology

Figure 6: Influence of the mass throughput on the viscosity the probability of a particle meeting a bead increases and therefore the product is sheared more often. This possibly leads to a decrease in the viscosity. Afterwards, a further increase in the throughput does not have any further major effect. The viscosity remains at a value of more than 200 mPas. The effect of the flow rate is similar with a bead size of 0.3 mm, but the lowest viscosity is higher than with larger beads, because of the lower throughput that is achievable. A higher throughput would lead to packing of the smaller beads and to a high wear of machine parts.

Why viscosity should be low

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Studies have shown that the viscosity and the flow behaviour of particle suspensions depend mainly on the adhesive forces [1]. Therefore, the particle size, the solid concentration and the stabilization of the suspension play a major role. It is sometimes assumed that the flow behaviour is Newtonian and, as soon as a certain shear rate is reached, the viscosity is constant [1]. However, it is difficult to tell which viscosity the material actually has in the mill, because the shear rate under these conditions is much higher than that which can be achieved with a viscometer. With a thixotropic behaviour, the periods spent in different areas, with different shear rates, have an effect. The high shear rate has to be exerted for a certain time in order to achieve the minimum viscosity. Therefore, it is helpful if the product suspension is already sheared, for example with a stirrer and a gear pump, before it goes into the mill. An increased throughput allows less time for the formation of structures like agglomerates in certain areas such as pipes, hoses, and valves. Keeping the viscosity to a minimum is especially desirable for the dispersing process, in order to avoid the packing of the beads and the clogging of the sieve [4, 5]. A higher viscosity also means that more energy goes into the displacement of the liquid, leading to an insufficient grinding process [3]. Another way of increasing the shear stress in the product is to optimize the tip speed. However, an increase in tip speed has the disadvantage of increasing the wear on machine parts in the grinding chamber and reagglomeration might also occur, due to the higher energy input, as shown in Figure 2. For this reason, the tip speed was kept constant in these experiments.

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www.coloris-gcc.com Colorants for In-Plant and P.O.S Tinting Systems

References [1] Stenger F., Peukert W., The role of particle interactions on suspension rheology – application to submicron grinding in stirred ball mills, Chemical Engineering Technology 26 (2003) [2] Schilde C., Arlt C., Kwade A., Einfluss des Dispergierprozesses bei der Herstellung nanopartikelverstärkter Verbundwerkstoffe, Chemie Ingenieur Technik No. 6, Wiley-VCH Verlag, Weinheim, 2009 [3] Breitung-Faes S., Kwade A.,: Produktgestaltung bei der Nanozerkleinerung durch Einsatz kleinster Mahlkörper, Chemie Ingenieur Technik No. 6, Wiley-VCH Verlag, Weinheim, 2009


03 l 2010


The Colorants Company

THE COLORANTS COMP THE COLORANTS COMPANY


22.02.2010 13:36:19

Technical Paper Wood coatings

Longer lasting, not stressing the environment Waterborne UV coatings for exterior wood application

* Corresponding Author: Jürgen Lippemeier Bayer MaterialScience T +34 93 228 4167 juergen.lippemeier@ bayermaterialscience.com

European Coatings Conference: Polyurethanes for high performance coatings 7-8 December, 2010 Berlin, Germany www.europeancoatings.com/events

Jürgen Lippemeier* Stefan Sommer Arno Nennemann The exterior wood coatings market is dominated by waterborne 1K acrylic dispersions. These have limited resistance properties and long-term weather durability. Standard outdoor coatings only exhibit long-term weather durability of four to five years, whereas the market for exterior wood applications demands eight years. A new generation of waterborne, UV-curing polyurethane dispersions enables the development of coatings with excellent weather protection, good mechanical properties and high chemical resistance.

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adiation-curable, waterborne polyurethane dispersions have been established in wood and furniture finishing since the mid-1990s. This is thanks to their excellent coating properties, environmental compatibility and high productivity. When using appropriate drying equipment in combination with very fast UV-curing, the process time can be reduced to only a few minutes. Waterborne, polyurethane dispersions are solvent-free and therefore meet the strict require-

Figure 1: Chemical resistance in white-pigmented coating material (0: worst score, 5: best score)

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ments of VOC legislation. Their high molecular weight makes the dispersions physically drying. The advantage is lower dust susceptibility as well as reduced shrinkage during radiation curing.

Special protection Special requirements exist for wood construction work in the outdoor sector. These are on the one hand long life and on the other hand dimensional stability. To ensure this, the wood must be specially protected [2]: Constructive wood protection: This means, among other things, a reduction in exposure to damp conditions, for example, through protection against precipitation or water logging and an improvement in wood ventilation. Chemical wood protection: Chemical wood protection, which is subject to the mandatory regulations DIN 68800 [4], is the impregnation of the wood with the aid of biocides for defence against wood-damaging organisms. Physical wood protection: This consists of the application of a coating which is intended to protect the wood against the uptake of moisture and to regulate the moisture balance. In addition, the coating must provide protection against UV radiation. The material may also additionally offer chemical wood protection. However, deficient constructive and/or chemical wood protection cannot be compensated by physical wood protection. Only this form of wood protection is discussed here. In physical wood protection, a distinction is made between clear, transparent coatings and opaque, pigmented coatings. Since wood is hygroscopic, its moisture level changes constantly. An essential duty of the coating is therefore to regulate the moisture balance, i.e. to slow the uptake and release of water. DIN 68360 states that wood for outdoor use should have a moisture content of about 13 % before coating. However, wood components in the outdoor sector are subject to moisture-content variations of 12-21 % after coating. It is therefore evident that the coating is subjected to constant mechanical stresses due to movement within the wood caused by swelling and shrinking. Regulation of the moisture balance reduces this. A coating is intended to allow slow permeation of water and consequently to keep the variations at a minimum. To ensure that the coating does not crack or flake off during this movement, it must remain flexible over a long


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Figure 2: Comparison of pendulum hardness and flexibility from tensile stresselongation experiments in white-pigmented coating material

period of time and be resistant to polymer degradation which leads to brittleness. Premature photochemical degradation of the polymers or physical aging cause standard, commercial, waterborne paints show a reduction in elasticity within four to five years. The consequence is that the coating can no longer withstand the swelling and shrinking of the wood. However, industry requires a life cycle to renovation of eight years for exterior coatings [3]. The prerequisite is that the coating have excellent adhesion to the wood substrate, even when exposed to moisture. Furthermore, so-called “blushing” should not occur in transparent systems. In addition, it is desirable for the wood moisture content to be below 20 % at all times, since it is at this level that the wood is best protected against mould infestation and blue staining [2]. Protection against UV light is also crucial for the coating, as it is important that it neither yellows nor become brittle due to polymer degradation nor to lose gloss. The coating must effectively protect the wood against UV radiation from sunlight, since this destroys the lignin and cellulose present in the wood. In the absence of adequate UV protection, the lignin degradation products are washed out and discoloration, greying and cracking occur. Lignin has an absorption maximum at about 280 nm [2] and damage occurs up to a wavelength of 440 nm [3]. Cellulose starts absorbing radiation below 200 nm and up to a wavelength of 400 nm [2]. Thus it can be seen that protection against UV radiation must cover a wide wavelength range. This is generally not a problem in the case of opaque paints as the pigments present in them protect the wood adequately. In the case of transparent systems, UV-absorbers and radical scavengers (HALS) help to ensure protection.

Significant developments

Figure 3: Permeation of water through pigmented coatings for exterior applications (gravimetric measurement of the water loss through a polymer membrane)

Figure 4: Evaluation of crack formation in coatings based on a one-component polyacrylate dispersion and a one-component UV-curing polyurethane dispersion after outdoor weathering in Barcelona, Spain

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Waterborne, one-component dispersions dominate the environmentally friendly, coating-systems market for exterior use. A distinction is made here between radiation-curable polyurethane dispersions and polyacrylate dispersions. One-component, polyacrylate dispersions are distinguished by good weathering stability. They generally have the disadvantage of poor flexibility of the resulting coatings; although this can be improved by reducing the glass-transition temperature. However, this is at the expense of the blocking resistance and dirt absorption. In the case of one-component, polyurethane dispersions, it is possible to establish a balanced equilibrium between hardness (blocking resistance) and flexibility. However, these systems have not displaced one-component polyacrylate dispersions on the market owing to raw material costs and play a minor role for exterior applications. Following the significant developments in waterborne, radiation-curable polyurethane coatings in wood/furniture finishing which have occurred since the mid-1990s, their excellent properties have now been used to improve exterior coatings. In order to prevent photochemical degradation of the polymers and associated effects such as gloss reduction, yellowing, chalking and reduction in flexibility, raw ma-


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“Wood Coatings” F. Bulian/ J. Graystone www.elsevier.com

terials which cannot be photochemically degraded are used, i.e. aromatic compounds and polyether chains are avoided. The backbone, which is based on aliphatic polyester acrylates, does not in principle differ significantly from the high-quality UV dispersions employed to date for wood/furniture finishes. When choosing the components, however, the good chemical resistance of the coating and, in spite of high hardness, adequate flexibility in addition to weathering resistance had to be taken into consideration.

Figure 5: Weathering tests in accordance with DIN EN 927-6; gloss reduction and yellowing of white-pigmented coatings on pine

Better chemical resistance Waterborne, radiation-curable, polyurethane coatings have a significantly better chemical resistance than waterborne, one-component polyacrylate systems. This is also clearly evident from Figure 1. Compared to standard, commercial, waterborne, radiation-curable polyurethane coatings for interior use, the new waterborne UV coating for the outdoor sector performs equally well [6]. The flexibility mentioned above was an important feature to be taken into consideration in the development of this new coatings raw material. Sufficiently high flexibility combined with high hardness are features of the new product. This is in contrast to the established waterborne UV dispersion for interior applications and waterborne one-component polyacrylate dispersion for exterior applications (Figure 2). On top of flexibility, low water permeation is crucial to prevent cracking. The crosslinking density has a significant effect on the barrier properties. This means that the higher the proportion of non-crosslinked one-component dispersion, the greater the permeation of water through the coating film. The use of physically drying, noncrosslinking polyacrylate primary dispersions has been seen to be particularly disadvantageous (Figure 3), as the wood coated with it is subjected to significantly greater swelling and shrinking movements. This results in cracking (Figure 4). Apart from the outdoor weathering tests, standardized accelerated weathering tests according to DIN 927-6 have been performed. During the standardized UVA weathering cycles, the coated wood substrates were additionally sprayed with water. The change in humidity and irradiation significantly increased the potential for damage. Swelling caused by moisture penetration and the subsequent rapid drying can result in cracking. Even more moisture can consequently enter the sample during the next weathering cycle, until the point where the sample can no longer dry out and the coating forms blisters or detaches completely. Weathering has been investigated in various comparative weathering tests. Results showed that the correct choice of UV absorbers and free-radical scavengers also play a crucial role. Good results were achieved with 2-hydroxyphenyl-s-triazine as UV absorber.

Good weathering

Figure 6: Polymer degradation after 12 months in accordance with DIN EN 927-3; corresponds to actual outdoor weathering for four years [3]

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The tests also indicated that the new radiation-curable, polyurethane dispersion gives excellent weathering properties (Figure 5). The new waterborne UV system retains gloss significantly better than a waterborne, one-component system. However, somewhat stronger yellowing is observed in the waterborne UV coating. Nevertheless, the fact that significantly less yellowing is observed in the one-component coating is due to the chalking which took place. This made the coating appear whiter than it actually was. In addition, weathering tests have been performed according to ASTM G 154-06. The new waterborne UV coating performed very well in unpigmented formulations [6]. After 3 000 hours, the reduction in gloss was only 6 %. The positive weathering results for the new waterborne UV coating have been confirmed by an independent


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Technical Paper Wood coatings study [3]. The systems investigated were stressed for 12 months in accordance with DIN EN 927-3 and the polymer degradation was investigated by means of IR spectroscopy (Figure 6). It can be seen that the corresponding coatings showed almost no polymer degradation after weathering. Furthermore, the study showed that UV coatings based on this raw material withstand the DIN EN 927-3, outdoor-weathering test for 24 months without film damage and yellowing. DIN EN 927-3, which only demands weathering resistance for 12 months, corresponds to a realistic weathering exposure of four years. It can therefore be assumed that the new waterborne UV coating will withstand actual exposure for eight years and consequently will meet the wood-industry requirement for a renovation interval of at least eight years.

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References [1] UV Coatings, Schwalm R., Elsevier, 2007 [2] Holzbeschichtung [Wood Coating], Prieto J./ Keine J., Vincentz, 2007 [3] F inal report on research project, WKI Report: 0339933, Development and trialing of a durable wood coating using novel polymeric materials for coating systems, 2006 [4] Wood, a traditional material with a future; Brickenstein R., WKI Report: 331998; Building with wood and wood materials; Brunswick 1998 [5] EP-B 0753531, Bayer MaterialScience AG [6] L ippemeier J., Sommer S., Nennemann A., (2009), Waterborne UV coatings for exterior Wood application, RadTech 2009, Nice

Results at a glance

A new generation of waterborne UV polyurethane dispersions for weather resistant coatings has been developed. They are superior in many aspects to standard waterborne, one-component polyacrylate dispersions currently on the market. Coatings made of such polyurethane dispersions showed excellent weathering protection, balanced mechanical properties and a very good chemical resistance and are suitable both for wood and furniture coatings. Apart from the advantages mentioned, rapid curing and blocking resistance of the coatings are also achieved. This results in a significant increase in productivity. These systems are environmentally friendly and comply with VOC guidelines. The market need for renovation intervals of at least eight years has been successfully met. Current evaluation already indicates similar positive results with the new waterborne UV binders for PVC substrates. This opens the potential for plastic window frame coatings.

www.european-coatings.com 03 l 2010 European Coatings J OURNAL


22.02.2010 13:41:03

Technical Paper Sol-gel systems

Cool solutions Waterborne sol-gel metal pretreatment system cures at low temperatures

* Corresponding Author: Dr. Albert Philipp Evonik Degussa T +49 7623 91 85 67 [email protected]

“Corrosion and Corrosion Control” R. Winston Revie www.wiley.com

Philipp Albert Waterborne sol-gel systems based on organofunctional silanes offer an environmentally-friendly alternative to hazardous traditional metal pretreatment systems. Sol-gel films can themselves improve resistance to oxidation and corrosion or can enhance the performance of coatings applied over them. A new sol-gel system can be used even where low-temperature curing is required.

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he first silicon alkoxide was synthesised from SiCl4 and alcohol by Ebelmen in 1845 [1]. He also realised that the compound gelled when exposed to the atmosphere. However, this group of materials, known as silanes, and their properties only attracted the interest of a few chemists. About 100 years later, this sol-gel technology was developed as an alternative process for the preparation of glasses and ceramics at considerably reduced temperatures [2, 3].

A later step in sol-gel development was the preparation and investigation of novel organic-inorganic hybrid systems [4]. The advantage of these new hybrid materials as coatings or corrosion protection systems for protecting metals from oxidation, thermal and chemical corrosion was realised and investigated [5, 6]. Several sol-gel based coatings based on oxides or organic-inorganic hybrids have been developed in the past. Most of the organic-inorganic systems contain organic solvents and are activated by the addition of water. One disadvantage of these water-activated sol-gel systems is their limited processing time, since they are ‘living’ systems which form gels after a period of hours or days, and so can only be applied to substrates after a defined activation time. A further step forward in sol-gel technology was the development of almost VOC-free waterborne organic-inorganic sol-gel systems. Such systems are available in the market under the “Hydrosil” and “Sivo Sol” brand names, for example. One such system based on inorganic particles and organofunctional silanes has been presented earlier [7]. The newest development of these waterborne sol-gel systems is “Dynasylan Sivo 160”, a stable system that can be cured at relatively low temperatures. It is shown below that this material can effectively improve resistance to salt spray testing in several different situations.

Sol-gel systems show promise for metal pretreatment

Figure 1: Schematic representation of the process for producing a waterborne solgel product, starting with inorganic particles

Figure 2: Scanning electron micrograph of a cured “Dynasylan Sivo 110” layer etched in an O2 plasma

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The area of metal treatment offers a wide range of challenges, from widely differing substrates to a wide range of specifications and special performance requirements. It is also an area of great interest, since metal degradation and corrosion is an important economic factor. Steel, aluminium and hot dip galvanised (HDG) steel need to be protected against corrosion on a huge industrial scale. In the past this has usually been done by using chromate, zinc or phosphating processes. Newer corrosion protection systems include the use of metal fluoride based formulations. Because all of these systems are environmentally questionable, the industry is still looking for new pretreatment systems with efficient performance. One answer to this demand could be formulations based on waterborne sol-gel systems, as they provide an environmentally friendly basis for metal protection systems. They offer all the advantages of sol-gel systems and provide special advantages because of their oligomeric polysiloxane structure. These molecules have: »»An excellent wetting effect; »»High reactivity with the metal surface; »»An organofunctional group that can react with the subsequent topcoat; »»A high crosslink density preventing water and chloride penetration.


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Technical Paper Sol-gel systems Evolution of waterborne sol-gel systems Organofunctional silanes are the precursors for the design of hybrid sol-gel systems. In the presence of water and catalysts, organofunctional silanes hydrolyse and release alcohol. As the silanols now formed are not stable they undergo a further reaction, the condensation step, and form stable Si-O-Si bonds. The hydrolysed silane molecules grow by condensation, resulting in a higher molecular weight. When the molecular weight is high enough a sol can be formed, which is still reactive and can undergo a further reaction to form gels. It is therefore a great challenge to design waterborne and VOC-free sol-gel systems which form stable sols. The first commercial waterborne and VOC-free sol-gel systems were introduced to the market in the 1990s by Evonik Degussa under the trade name “Dynasylan Hydrosil”. Another technology for the design of waterborne sol-gel systems is shown in Figure 1 and uses inorganic particles. In a special process, organofunctional silanes are added to the inorganic particles and are hydrolysed. The reactive silanols thus formed undergo a condensation with the inorganic particles and form stable Si-O-Si bonds. During this process the surface of the inorganic particles is modified and the particles are additionally stabilised. The alcohol from the hydrolysis can be removed and the final sol-gel product is reactive, waterborne, VOC-free and stable. The application of a sol-gel system is carried out in the liquid state and therefore the stable sol is applied to the surface. When the water evaporates the sol can react

Results at a glance Traditional metal pretreatment systems often pose both environmental and occupational health hazards. Waterborne sol-gel systems based on organofunctional silanes offer an environmentally friendly alternative. Stable sol-gel systems now exist which avoid the problem of having a limited time period in which to apply the material to the substrate. Until now, high curing temperatures have limited their range of applications.

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Test results are presented on a newly developed organic-inorganic sol-gel system which can be cured at low temperatures or even ambient temperature. It is shown that the new product can enhance the performance of powder coatings applied over it, provided the cleaning procedure is correctly chosen. It can also provide protection as a single layer (eg, on galvanised steel) whether applied alone or as part of a formulated coating.



SIGMUND LINDNER GmbH Oberwarmensteinacher Str. 38 D-95485 Warmensteinach Phone (++49) 92 77 - 99 40 Fax (++49) 92 77 - 9 94 99 E-Mail: [email protected] www.sili.eu

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Your innovative and reliable partner for 155 years

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Technical Paper Sol-gel systems

Figure 3: Sandblasted steel powder coated and exposed for 500 hours in an NSS chamber: left, without primer; right, with sol-gel pretreatment

Figure 4: Particle size distribution by volume of the sol in “Dynasylan Sivo 160” measured by photon correlation spectroscopy (PCS)

further and can form a gel. This step usually needs a raised temperature for good network formation of the sol via condensation. Figure 2 shows a scanning electron microscope micrograph of such a product which was cured at 200 °C. The organic part of the system was partially removed by etching. This figure shows the dense packing of the sol particles in the cured sol-gel layer. This packing results in a dense coating with high hardness and good protective properties, even at a low layer thickness. One such commercial product is “Dynasylan Sivo 110”, which is an organic-inorganic base resin and should be formulated for optimised performance. A typical application of such a formulation is as a primer on sandblasted steel in combination with a powder coating. The example in Figure 3 should show the potential of this approach in combination with a powder coating: The high curing temperature required by this sol-gel coating is no problem when it is used with powder coatings. Nevertheless, it is a restriction for many other applications. A new waterborne sol-gel system for low temperature curing has therefore been developed.

Alternative synthesis route lowers curing temperatures In contrast to the system just described, the synthesis of the low temperature curing sol-gel system does not start with inorganic particles. Special types of silanes are used as precursors, and in the complex hydrolysis and condensation process highly branched polysilanes with active silanol groups are formed. The highly crosslinked polysilanes form a stable sol. The final product is called “Dynasylan Sivo 160” and it is a waterborne and VOC-free liquid which cures at low temperatures. This newly designed sol-gel system offers a high potential for many applications. The graph in Figure 4 shows the particle size of the sol-gel system which was determined via photon correlation spectroscopy. This system has a pH of about 4.3 and can be easily diluted with water and other polar solvents. This makes it ideal as base resin or as an additive for both established and new environmentally-friendly metal treatment formulations.

Figure 5: Comparison of polyester coated magnesium alloys that were exposed to 250 hours in the CASS test just cleaned (blank) or pretreated after the cleaning procedure with chromate or a sol-gel coating

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Technical Paper Sol-gel systems The free silanol groups in the polysilane are stabilised and therefore the product has a shelf life of one year. In addition, this waterborne formulation was designed to be highly reactive at temperatures as low as 80 °C. This allows its use in new temperature-sensitive applications, where other sol-gel systems were not usable because of their high curing temperatures, or simply where high temperatures are not used in the production process. The silanol groups react with the metal surface as well as with other silanol groups and form a very tight twoto three-dimensional organic-inorganic network, which creates an excellent corrosion protection layer in combination with organic topcoats. It can be applied with well-known conventional methods used in the metal treatment industry such as spraying or immersion. Nevertheless, the cleaning of the metal surfaces is of great importance since the metal surface should not only be clean but also in the right condition for treatment with the sol-gel formulation. However, there are different cleaning procedures in technical use for different metal substrates and one has to evaluate which cleaning procedure will result in the best performance from the waterborne sol-gel systems.

Figure 6: Comparison of polyester coated magnesium alloys cleaned only by an alkaline cleaning procedure; corrosion test results after 1000 hours in the CASS test

Cleaning process is critical for good performance The following example demonstrates the importance of the cleaning procedure for the metal substrate magnesium when a waterborne sol-gel system is applied. The magnesium alloy was cleaned in an alkaline bath, rinsed, followed by treatment in an acidic water solution and finally rinsed with water. The cleaned magnesium alloy was pre-treated in one case with chromium and in the other case with “Dynasylan Sivo 160”. A polyester powder coating was applied to the blank and cleaned magnesium surface, to the chromium treated and to the sol-gel treated magnesium surface. The samples were scribed and a copper accelerated salt spray (CASS) test was carried out. The results after 250 hours in this test can be seen in Figure 5. It can be seen that the samples with the sol-gel pre-treatment performed worse after 250 hours in the CASS test. In further tests, a different cleaning procedure was applied to the alloy. The cleaning procedure was the same as described for the samples in Figure 5 but the acid treatment was omitted. The same pretreatment and the same polyester powder coating were used for preparation of the samples. The samples were again tested in the CASS test. The test results of the different pre-treated and powder coated magnesium alloys can be seen in Figure 6. Comparing the test results in Figure 6 it can be seen that the performance of the chromated and the sol-gel pre-treated and powder coated samples are comparable even after the longer test period of 1000 hours in the CASS test.

Figure 7: Comparison of passivated HDG steel (left) with the same material treated with low-temperature curing sol-gel coating (right) after 250 hours salt spray test

Figure 8: HDG steel plate blank (left) and treated with a formulation that contained 10 % solgel material after 150 hours in salt spray test

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Galvanised steel protected by sol-gel coating alone Steel is often protected against corrosion by a zinc layer. However, zinc is a difficult substrate as it undergoes

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Technical Paper Sol-gel systems corrosion after hours or days when exposed to the atmosphere. White rust will be formed, and if the surface should be coated this causes problems. Therefore the surface of hot-dip galvanised (HDG) steel, for example, is protected for transport and short-term storage by treatment with oil or by chemical passivation. Waterborne sol-gel systems can be used to improve the corrosion protection of passivated HDG steel, as demonstrated in the following example. The surface of the passivated HDG steel was cleaned with an organic solvent to remove dirt and oil from the production process and dirt from the environment. After the cleaning stage, the sample was immersed for 30 seconds in a “Dynasylan Sivo 160” solution (50 % dilution) and cured for 20 hours at room temperature. The treated samples were placed in a neutral salt spray test. The results after 250 hours salt spray test can be seen in Figure 7. Plain HDG steel will corrode in the atmosphere within a short time and form white rust. Waterborne sol-gel systems also offer an interesting potential for the corrosion protection of this substrate. However, optimisation of the sol-gel system is necessary and waterborne sol-gel systems can be used as additives or as an organicinorganic binder. The following example should demonstrate the potential of such a formulation based on the new low-temperature curing approach. The clean HDG steel plates were immersed for 30 seconds in a formulation that contained additives and 10 % of the sol-gel material. The system was cured after immersion for 10 min at 80 °C. A reference and the coated HDG steel plate were placed for 150 hours in neutral salt spray fog. The results of this test can be seen in Figure 8.

have a potential as either a binder or an additive in metal pretreatment systems.

í

REFERENCES [1] Ebelmen A., Ann., 1846, Vol. 57, p 331. [2] Sakka S., Trans. Indian Ceram. Soc., 1987, Vol. 46, p 1. [3] Sakka S., Kamia K., Jnl. Non-Cryst. Solids, 1982, Vol. 48, pp 31-46. [4] Schmidt H., Jnl. Non-Cryst. Solids, 1985, Vol. 73, p 681. [5] Guglielmi M., Jnl. Sol-Gel Sci. and Tech., 1997, Vol. 8, pp 443-449. [6] Mackenzie J. D., Bescher E. P., Jnl. Sol-Gel Sci. & Tech., 2000, Vol. 19, pp 23-29. [7] Borup B., Standke B., Waßmer C., Europ. Coat. Jnl., 2007, No. 11, pp 28-35.

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High performance now available at low temperatures Traditional metal pre-treatment systems that contain chromate are already banned in some applications. The pressure on environmental hazards as well as occupational health hazards from metal pre-treatment systems is growing, as can be seen in new regulations. Waterborne sol-gel systems can offer an alternative since they are environmentally friendly and can be formulated and optimised in many ways. These formulations contain reactive silanol groups which can undergo condensation with other silanol groups and can additionally react with the metal surface. The highly crosslinked surface layer passivates and protects the metal surface as a barrier against water and chloride. The latest waterborne sol-gel systems described offer low temperature curing and



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Technical Paper Concrete protection

More than skin deep Easily dispersed dry emulsion protects bulk and surface of cement mixtures

* Corresponding Author: Mustapha Sari Hexion T +33 149 376497 [email protected]

M. Sari* A. Christmann M.-C. Grisolet A new water repellent additive for cement-based materials is supplied in the form of a dry emulsion which is self-dispersing in water. On both grouting and facade materials, the emulsion product gave much better bulk hydrophobisation than standard water repellents. It also reduced colour changes after wet/dry cycling and algal growth.

H

ydrophobic compounds are quite often added to cementitious materials to improve their moisture resistance and avoid possible degradation of strength, visible efflorescence and algal growth. Different technologies have been developed, mostly for the finishing domain, based on waxes, salts of fatty acids, silicones, silanes and polysiloxanes. Though most of these products provide sufficient surface hydrophobicity, this in itself leads to problems with dispersibility, poor paste consistency, and difficulties in application [1]. Migration to the surface may occur so that, after hardening, the surface of the material is usually well hydrophobised but its bulk very often appears to be inadequately protected.

A new water repellent that greatly limits these problems has now been developed, based on the dry emulsion concept [2]. This provides easy dispersion and a more homogeneous presence within the final material. Some results relevant to grouting applications were presented in an earlier paper [3]. Application results are presented below showing specific benefits when the material is used alone or in combination with other water-repelling agents (WR). Grouting and facade applications are the main areas considered here.

Dry emulsion product is self-dispersing The new hydrophobic agent (dry emulsion technology = DET) presented below is characterised by its ease of dispersion and ease of mixing. Figure 1 illustrates the ease of redispersion of the powder in water, using a very simple test: 0.1 g of the hydrophobic agent is added to 90 ml of water without stirring, and is left for a few minutes. As can be seen on the photographs in Figure 1, the powder is easily wetted and self-disperses. The other standard hydrophobic agents (stearate and silane technologies) remain at the surface of the water and are difficult to disperse in a stable and homogeneous manner. This high dispersion rate ensures immediate diffusion into the cementitious paste, which avoids additional mix-

Figure 1: Dispersion of the dry emulsion based technology (DET) product compared to conventional technologies after (a) 1 min 45 sec and (b) 3 min

Figure 2: Contact angles and drop penetration times for grout mortars admixed with various water repellents

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Technical Paper Concrete protection ing. This also confers an exceptional workability to the paste, ensuring easy application and finishing. The application results given below illustrate its additional benefits in grouts and facade renders.

New product is tested against four standard materials The dry emulsion technology was benchmarked against two powder water repellents (“SR1” and “SR3”) based on silicone resins, and a standard mix composed of magnesium stearate and oleate (labelled “S/O”); the oleate “O” was also used alone for comparison. The samples without water repellent are labelled “Ref”. The active content in all cases was 0.3 wt – %, (levels of S and O being 0.15 wt – % each when combined). Compensation for the addition of water repellent was made by changing the sand content of the mixture. For the grout mortars, bars 5 mm thick were prepared with a width of 30 mm and a length of 100 mm. They were stored for 24 hours at T = 23 ± 2 °C and a relative humidity (RH) of 95 ±5 %, then demoulded and stored under standard conditions (T = 23 ± 2 °C, RH = 50 ± 5 %). In the case of the mortars used in facade applications, 15 mm thick circular test pieces were prepared with a diameter of 50 mm; they were scratched on their free

Results at a glance Hydrophobic additives for cement-based materials can improve their resistance to moisture penetration and so reduce efflorescence, algal growth and other forms of degradation. However, as existing standard materials are intrinsically hydrophobic, they are usually difficult to disperse uniformly, so that the bulk material is not well protected. A new hydrophobic additive is supplied in the form of a dry emulsion which is selfdispersing in water. Various additives tested on both grouting and facade materials all gave effective surface hydrophobisation but the emulsion product gave much better bulk protection. Combining the new material with standard stearate or oleate water repellents could give even better performance. The dry emulsion was also the most effective at reducing colour changes on coloured concrete after wet/dry cycling. In other tests it greatly reduced algal growth.

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Figure 3: Contact angles and drop penetration times of DET and DET/ oleate-modified facade mortars (O = oleate treatment)

surface shortly after setting commenced and then stored under standard conditions for 28 days.

Details of contact angle and water penetration tests The hydrophobisation of the mortars was studied on both the surface and the bulk, using contact angle measurements and drop penetration times. Thus, information was collected on the uniformity of the water-repellent effect. After 28 days, contact angle measurements were performed using an “EasyDrop” device from Kruss, the water droplet being deposited onto the air-dried surface of the sample. The droplet penetration times, Tp, was also fol-

lowed. The same measurements were performed in the bulk of the samples. To measure the droplet penetration time Tp, image acquisition was performed every 1/25 second for seven seconds, and then for each subsequent second until full penetration of the droplet. The contact angle, defined as being the tangent to the droplet outline and the base line, was determined immediately after the deposition of the droplet. A colorimetric technique was used to characterise the homogeneity of the mortar surface before and after immersion in water. A Minolta “CM-3610d” spectrophotometer was used for this study. The measurements were performed with the small mask and the mode used was specular reflection, 0 ° excluded (SCE 0), with D65 illuminant at 10 °.

Figure 4: Contact angles and drop penetration times measured on abraded grout samples

Figure 5: Contact angles and drop penetration times measured on broken facade render samples (O = oleate treatment)

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Figure 6: Coloured grout samples partially immersed in water after 9 min of immersion (left) and surface appearance (right) of coloured samples after four cycles of partial immersion in water (solid line shows immersed area and dotted line the non-immersed area)

Several products hydrophobise surfaces effectively The contact angles of water droplets give an indication of the surface hydrophobicity of the mortars and of the modification of their surface tension (the surface roughness and defects have to be taken into account for this appraisal). The drop penetration times give complementary information. Figure 2 shows that all water repellents tested create a much increased surface hydrophobicity as compared to the control, in terms of both contact angles and drop penetration times. A few seconds are needed for complete absorption of the droplet in the case of the reference material, while 1000 seconds or more are needed in the case of the hydrophobised samples. Stearates and oleates of metals such as Mg, Ca and Zn are often combined in facade renders to optimise protection. Here, the DET water repellent was evaluated in a

system containing oleate. Figure 3 shows contact angles and drop penetration times for the systems admixed with oleate and DET respectively, compared to the ‘DET– oleate’ system. A synergy between the two water repellents can be clearly observed. Taking into account the poor dispersibility of standard hydrophobic agents, this combination offers a real advantage, as it is still characterised by its high dispersibility and provides extremely efficient hydrophobisation.

Emulsion gives most effective bulk hydrophobisation Correct hydrophobisation of the bulk of the mortar is essential, as the material may crack and its surface may be eroded over time. Contact angles and drop penetration times were therefore measured in the bulk of the grouts and facade renders studied.

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23.02.2010 09:43:17

Technical Paper Concrete protection In the case of the grouts, addition of the DET leads to contact angles that are significantly higher than when silicone resins are used. Indeed, the silicone resins produce values that are similar to those of the additive-free mortar (see Figure 4). The drop penetration times Tp vary in the same way. The DET-admixed mortar gave 400 seconds while just a few seconds were necessary for complete absorption of the water droplet with the SR1 and SR3-modified mortars. Only DET confers uniform hydrophobisation on the mortar. Similarly, in the case of the facade renders, Figure 5 shows that the stearate-oleate system does not uniformly hydrophobise the bulk of the render. The addition of DET significantly increases the drop penetration times, especially when used in combination with the oleate; in this case, the drop penetration times are very high. The combination of the oleate and DET also produces a beading effect even in the bulk of the render.

Partial immersion test evaluates colour stability “Materials Science of Concrete” F. Young, J.P. Skalny www.wiley.com

Ensuring long-lasting visual appearance has always been a key issue in construction, especially when dealing with coloured materials. If the mortars are based only on Portland cement (OPC), primary and secondary efflorescences are often a source of problems. Thus, specific systems have been developed, using special binders or combining OPC with pozzolanic materials.

Additional modification with water repellents ensures a long-lasting visual appearance. The different water repellents were therefore tested in coloured grouts to evaluate their impact on the surface appearance. The coloured samples were partially immersed in water at 23 °C for 24 hours (see Figure 6a), then dried at 23 °C and 50 % RH for 24 hours. This cycle was repeated four times. A rapid propagation of the moisture front could be seen in the non-admixed mortar after only a few minutes immersion. The mortar modified with SR-1 shows a small rise of the moisture front whereas no damp rise can be observed for the DET-modified mortar. These results corroborate the uniform hydrophobisation conferred on the mortar by the DET, as noted in the test results discussed previously. Figure 6b shows the same samples after four of the water immersion/drying cycles described above. Addition of 0.3 % DET greatly reduces efflorescence, and this is even more significant after repeated exposure of the mortar to water.

Colour changes are least with new additive Figure 7a shows the evolution of the samples’ colour coordinates in the immersed area (lower part of the samples) as a function of the number of cycles. The evolution of the L* coordinate (whiteness) as a function of the number of cycles is comparable for all materials.

Figure 7: Colour coordinates L* (whiteness) and a* (intensity of red colour) corresponding to (a) the immersed area as a function of the immersion cycles and (b) the nonimmersed area, before and after four immersion cycles

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Figure 8: Facade renders admixed with different water repellents and wetted out for three weeks with an algal dispersion (equidistant vertical marks correspond to the positions of the sprinklers)

A decrease in whiteness can be observed after the first cycle. Subsequently, the samples whiten up to the third cycle then their colour becomes stable. This process is probably linked to the formation of secondary efflorescence. An inverse change can be observed for the red colour index a*. After an increase subsequent to the first cycle, it rapidly decreases until the third cycle, and then remains relatively constant. A simple visual observation shows that, indeed, the 0.3 % DET-modified sample has the highest redness. Figure 7b shows the evolution of the colour coordinates in the non-immersed area before and after the four immersion/drying cycles. A significant impact of moisture on colour can be observed, even in the non-immersed area (due to migration of the salts and their entrainment by the moisture front). The DET-admixed sample shows colour coordinates that are the closest to the original, and the highest red intensity.

New water repellent also reduces algal contamination Ensuring good protection against algal growth is also essential for facade applications. An experimental device was set up to allow visual appraisal of the resistance of the mortars to possible contamination by biofilms. Figure 8 shows the appearance of different renders sprayed during a period of three weeks (without changing the bath) with an aqueous solution containing algae. The samples were wetted out at a fixed rate once a day and then exposed to light for 12 hours per day. It can be seen that the sample containing DET is far less contami-

nated than either the control or the samples admixed with other water repellents.

Dry emulsion product shows best overall performance The new powder water repellent identified as DET in this paper shows particular advantages in terms of redispersibility. It confers excellent workability on the fresh cementitious blends to which it is added. After hardening, the hydrophobised materials show uniform surface and bulk characteristics, which provides a better, homogeneous and more durable appearance. Used in combination with selected hydrophobic agents (of the magnesium stearate and oleate type, for instance), it demonstrates clear synergies. The water resistance is greatly improved, in terms of lower water uptake, higher contact angles and droplet penetration times. The concept appears particularly attractive for coloured materials, where significant improvements in visual characteristics are combined with a reduced tendency to organic contamination.

í

REFERENCES [1] Butler D., Gubbels F., Granulated hydrophobic additive for cementitious materials, USP, 2008, No. 7,410,538. [2] Mercier J. M. et al, WO 2005/118683. [3] Christmann A. et al, A new concept of water repellents for cement-based materials, Proc. MixBuild Int. Sci. & Technol. Conf., Moscow, Russia; Cement. Concrete. Dry building mixtures, 2008, No.

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Events European Coatings Conference

A sea full of new ideas European Coatings Conference on the latest developments in marine coatings Sonja Specks Coatings experts from 15 nations gathered in Berlin to debate maritime coatings. Environmental protection and fresh ideas for antifouling products topped the bill.

T

his was the second time the conference on marine coatings and antifouling properties was held. Over the course of 13 presentations, the experts discussed recent developments and current universities studies to the public. The conference also presented an ideal opportunity for networking.

“No biocide comes close to being as effective as the banned TBT.” – Erik Risberg, Jotun Protecting against invasive species The first speaker, Eric Risberg, from Jotun, gave an overview of how environmental issues impinge on antifouling research. He believed that marine coatings in this field ought to contribute to keeping invasive species out of microcosms. The translocation of molluscs and other species to other parts of the world via ships is dangerous for local marine life. In his opinion, “no biocide comes close to being as effective as the banned TBT”. It was important, he said, for research to come up with new products that are as efficient as tributyl tin (TBT), but are harmless to the environment and function in difficult waters, such as shipping lanes.

Determining the burden on seas and ports Dr. Bert van Hattum, from the University of Amsterdam, showed that the cumulative leaching of just 1 microgramme of paint per square centimetre in Rotterdam docks amounts to some four to 13 tons over the course of a year. The threshold exposure concentration for life

A video interview with Dr. Bert van Hattum will be online soon: www.europeancoatings.com/ videos

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forms is 1-100 nanograms per litre. This would explain such phenomena as imposex, by which some marine species develop sex organs that are in contrast to their actual sex. Such a scenario could be identified and predicted more easily by using the MAMPEC model (Marine Antifoulant Model to Predict Environmental Concentrations). Its objective is to create realistic emission scenarios for coastal zones. Data on emission levels and environmental quality are currently being gathered at various sea coasts. These include measurements of water data, such as salinity, sediment characteristics and water movement.

Survey on coating properties In a survey carried out at the conference, 84 % of respondents believed that antifouling properties afforded the greatest scope for improving the performance of marine coatings. The result was clear-cut, placing antifouling far ahead of corrosion protection, adhesion and abrasion protection.

Enzymes as antifouling agents An environmentally friendly method for combating fouling was presented by Knut Allermann from Biolocus. His studies suggest that enzymes in aerogel offer longer resistance to mollusc infestation. Coatings containing enzymes prevent molluscs from gaining a foothold on the substrate. The advantages of enzymes, he noted, were that they are cheap and 100 % degradable in the sea. A tanker was painted with a solventbased coating containing these enzymes and spent 20 months sailing in tropical waters. The results were the same as those yielded by traditional cuprous paints. Allermann believes that “waterbased coatings for marine coatings still have a long way to go.”

í

Source: Uwe Steinbrich/Pixelio

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ECJ_

Reader`s Voice Titanium dioxide

Comment on: “Keep your powder dry” * By Ulrich Gesenhues

Contact: Ulrich Gesenhues T +49 2066 22 2329 U.Gesenhues@ sachtleben.de

T

he paper proposes novel explanations for the photocatalytic activity of TiO2 that do not comply with the scientific and technical literature in general and particularly after 1995. As usual in such a situation, the authors should reveal their chemical and physical experimental evidence, and assumptions and models used, in detail so that the reader may follow their conclusions. In particular: The authors should describe the samples investigated in more detail (commercial samples: % residual rutile, analysis of calcination additives and impurities, spec.surface area; anatase gel: is it metatitanic acid from the sulphate process? Crystal size, spec.surface area ...), as these parameters are quite important in photocatalytic performance (references [10] and [11] by the authors; U. Gesenhues, double laison 1996, Chem. Eng. Technol. 2001, J. Photochem. Photobiol. A: Chem. 2001). Further, in contrast to the authors’ findings, desorption of physisorbed H2O from the surface of calcined, not pyrogenic TiO2 is complete only at approx. 400 °C while chemisorbed H2O is stable beyond (H. P. Boehm; T. Rentschler, Eur. Coat. J. 1997, FARBE UND LACK 2000). It is calculated from the amounts of H2O desorbed in the authors' experiments up to 197 °C that they correspond to approx. 1.3 - 1.8 layers or more of physisorbed H2O molecules on the TiO2 crystal; thus, the residual amounts of physisorbed H2O and the influence of chemisorbed H2O in the authors’ experiments remain unclear. In addition, the case of Al-doped rutile has shown that the large differences in photoactivity, often observed under identical weathering conditions between TiO2 pigments without surface-treatment, are not due to differences in H2O sorption at the pigment surface, but to semiconductor properties of the crystalline layers below (U. Gesenhues, J. Photochem. Photobiol. A: Chem. 2001). A wealth of evidence has been accumulated in science and industry during the last four decades that it is the chemisorbed H2O (hydroxyls) and adsorbed O2 which carry the electrons and defect electrons generated by

* Letter to the Editor Ulrich Gesenhues, Sachtleben Chemie GmbH, comments on the technical paper “Keep your powder dry” by T. Dinkov and J. Stabryn which appeared in European Coatings Journal, 1/2010, pp 25-27. If you would like to express your opinion as well, do not hesitate to contact us: [email protected]. Also read our blog at www.european-coatings.com/blog

UV within the TiO2 crystal to the polymer matrix of paints and plastics, and specific chemical reactions have been formulated (e.g., [11] and U. Gesenhues, double laison 1996). It would be only fair if the authors could give their chemical reactions responsible for the loss in brightness they measured during the irradiation of the TiO2 powders in air without any organic compound involved. Further, paint films can be permeated easily by H2O (e.g., Völz et al.), so that drying the TiO2 pigment before paint manufacturing more carefully than done today would not improve weathering durability. And what about TiO2 in waterborne paint formulations? In contrast to the authors’ opinion, it is a matter of fact that in the production of rutile pigments by the sulphate process, calcination temperatures are equal to or slightly less than those for anatase (Sachtleben, plant and lab). Still anatase is clearly more photoactive, but only if water is present (U. Gesenhues, Polym. Deg. Stab. 2000). This result holds also when measured photoactivity is related to the specific surface of the TiO2 sample as the catalyst surface exposed to the reaction, so that any gel particles present in the pigment due to an incomplete calcination, as hypothesized by the authors, are included. It would be fair if the authors could reveal reference [12] (unpublished work) cited in support of their theory, and give specific surface and particle size of the sample, too. Besides, in their speculation the authors should mind that TiO2 is stoichiometric below 1000 °C and at O2 pressures of more than a few nanobar (e.g., Kofstad, LandoltBörnstein New Series). Further, in contrast to the authors' opinion, in the slow growth of ultrafine (> Coatings Basics Adrie Winkelaar, Sep. 2009, 154 pages, hardcover, 79,- € order-no. 474

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Market Place Novel products Cosolvent-free polyurethane dispersions

Instrument for flexible wetting tests

Wetting tests and measurements of the surface free energy on very large samples, on tilted or vertical and on enclosed surfaces – the “MobileDrop” from Krüss has all these possibilities in its program. The instrument in PDA format is operated with only one hand and a notebook and requires a measuring area of only a few square centimetres. Easily exchangeable dosing heads allow the rapid use of different test liquids. The field of application of the instrument has recently been extended by the introduction of the “MobileDrop HT” high-temperature version for measurements on hot surfaces. In the coating test on frying pans, etc., scientific measurements with this version have already replaced the crude “egg-frying” method. A dosing head with accurately adjustable dosing volume is also available, it is intended for use with standardised measurement instructions. Krüss GmbH DE-Hamburg [email protected] www.kruss.de

Tackifier with low VOCs Robert Kraemer GmbH has extended its range of tackifying resins. Alongside the low-VOC “Bremasin 1605”, which has proved a success in adhesives in the “EMICODE EC1” category, there is now also available “Bremasin VP 5737”, a tackifier which not only has low VOC values but also meets the requirements of the “Blue Angel” RAL UZ 113 environmental label. Despite its modified structure, it is still readily emulsified and displays good adhesion. In addition, “Bremasin VP 5770”, which is a very low-viscosity soft resin, is also RAL-compliant and is used as a hot-melt component for hard resins. It not only performs the functions of a solvent or plasticiser but also improves adhesion properties. This low-viscosity resin is used to prepare customised rosin ester compounds. Robert Kraemer GmbH & Co. KG DE-Rastede [email protected] www.rokra.com

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Non-contact ultrasonic transmitter

Bayer MaterialScience has introduced a new generation of cosolvent-free polyurethane (PU) dispersions to further improve the performance of waterborne environmentally friendly twocomponent polyurethane coatings for various substrates. For example, coatings based on “Bayhydrol U XP 2750” are hard, yet elastic – even in cold conditions – and very scratch-resistant. Developers from Bayer MaterialScience achieved this configuration of properties by incorporating self-healing segments into the polymer. The strengths of the aqueous binder “Bayhydrol U XP 2755” really come into their own in two-component PU systems for industrial wood and furniture coatings. The reactive dispersion produces coatings that dry very rapidly. “Bayhydrol U XP 2757”, on the other hand, has been developed specifically for waterborne soft feel and “comfort” coatings. This type of coating can transform “cold” plastics into surfaces that have a soft, warm and pleasant feel. Bayer MaterialScience AG DE-Leverkusen [email protected] www.bayermaterialscience.de

“Green” biocides for waterbased formulations ISP Performance Chemicals announced a new series of “greener” biocides offered under the “Nuosept” trade name that function as broad spectrum protection products for waterbased industrial formulations, such as coatings and adhesives. “Nuosept BMc 422”, offered as a greener biocide than previous generations of these products, features a synergistic combination of isothizolones for the prevention of Gram (-) and Gram (+) bacteria as well as fungi. A second product called “Nuosept W Concentrate” is classified as a low environmental impact biocide formulated with CMIT/MIT and Bronopol for broad spectrum protection at low use levels. Both biocides prevent microbial spoilage without contributing to the VOC or formaldehyde of the products preserved. According to the manufacturer, formulators of waterbased industrial products want to preserve their formulations with one biocide system that is both efficient and green, when compared with legacy offerings. International Specialty Products Inc. (ISP) USA-Wayne [email protected] www.ispcorp.com

The new “Echotel 355”, a two-wire electronic non-contact ultrasonic transmitter from Magnetrol International, performs liquid level, volume and open-channel flow measurements and is both powerful and userfriendly. This new, compact unit features a powerful 60 kHz ultrasonic transducer and advanced digital signal processing to reliably measure to a maximum range of 6 m. The transmitter can be configured on the spot with the menu-driven four-button LCD display; and it is also possible to perform configuration remotely with the digital “Hart” communications program or “PACTware”. This enables additional functionalities, such as capturing echo wave forms and viewing trend data, diagnostic conditions and all transmitter configuration parameters. Magnetrol International N.V. BE-Zele [email protected] www.magnetrol.be

Would you like to find more novel products? Take a look at the EC Market Navigator, your new value-added supply network: www.european-coatings.com/ marketnavigator


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Calendar of Events 2010 27 April 2010 Paint & Coatings Basics PRA Hampton, Middlesex/UK www.pra-world.com

13-15 April 2010 American Coatings Show Charlotte, NC/USA www.american-coatings-show.com 13-16 April 2010 3rd Paint Expo Karlsruhe/Germany www.paintexpo.de

11-12 May 2010 Principles of Waterborne Coatings PRA Hampton, Middlesex/UK www.pra-world.com

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Exhibitions

Conferences 9-12 March 2010 Interlakokraska 2010 Moscow/Russia www.maxima-expo.ru 11-12 March 2010 EuPIA Annual Conference Gent/Belgium www.eupia.org 12-14 April 2010 American Coatings Conference Charlotte, NC/USA www.american-coatings-show. com 27-28 April 2010 Migresives Closing Conference Ljubljana/Slovenia www.migresives.eu


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20-24 April 2010 Surface Technology Hannover/Germany www.hannovermesse.de

3-4 June 2010 European Coatings Conference: Fire retardant coatings IV Berlin/Germany www.european-coatings.com 28 June -2 July 2010 CoSi – 6th International Conference on Coatings Science Noordwijk/The Netherlands www.coatings-science.com

Seminars 31 March 2010 „Fundamentals of Performance Testing and Characterisation” OCCA Birstall (Batley), UK www.occa.org.uk/cnfrncs perftest/perftest_introVw.lasso

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9-12 March 2010 Interlakokraska 2010 Moscow/Russia www.maxima-expo.ru

18-25 May 2010 IPEX 2010 IIR Exhibitions Birmingham/UK www.ipex.org

29-31 March 2010 Middle East Coatings Show 2010 Dubai/U.A.E www.coatings-group.com 6-9 April 2010 Paints & Coatings – Moscow 2010 ITE Group Plc Moscow/Russia www.ite-exhibitions.com

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23-24 June 2010 Asia Pacific Coatings Show 2010 Jakarta/Indonesia www.coatingsgroup.com New events in our list 

or events with changes.

More coatings events at www.european-coatings.com events/coatings_calendar

03 l 2010

Coatings manufacturers are informed about your company events in our Events section. For more information please contact our sales team: Rüdiger Reschke, Tel. +49 511 9910-251, [email protected]


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