Paint & Coatings Industry 2010,09

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V I EWPOINT

Change is Good! You k now, I ha ve b een with PCI fo r a lmost 1 9 years, a nd I ha ve t o ad mit that 2 009 w as th e m ost challenging y ear for t he publishing industry, as well as t he c oatings in dustry. As you know, we all had to make changes – not only in the way we conducted our business, bu t a lso i n ou r personal lives. It wa s v ery s cary at f irst, w ondering what cha nges t he i ndustry w ould n eed to ma ke, a nd h ow t he cha nges w ould affect PCI, e specially when advertising slowed do wn a nd w e s aw r ising c osts on p ostage a nd p aper. Y es, I wa s skeptical back i n January 2009, but the uneasiness didn’t last long. I was blessed to be working at BNP Media, which was one step ahead in making plans on how to weather the storm. And, most of a ll I was ble ssed t o b e w orking w ith a v ery talented staff that was eager to make the changes that were necessary. It wa s ev ident t hat t he f irst i tem on the a genda wa s t o fo cus on p roviding our r eaders w ith t he s ame qua lity and q uantity o f e ditorial c ontent. W e created mor e ch oices on h ow t o obt ain information a nd a rticles on e merging technologies a nd th e l atest t rends a nd news in t he c oatings in dustry. W e expanded ou r “Online Features” s ection of ou r w ebsite ( www.pcimag.com) t o include several more articles each month. These a rticles a re l isted on ou r T able of Contents page in every issue. Over the past year and a ha lf we have also st rengthened o ur pre sence i n t he social me dia a rena i n or der t o b etter provide you with the most current news. We r egularly p ost c ontent on T witter, Facebook a nd L inkedIn. I f y ou ha ven’t already, be sure to sign up to follow us.

For t hose of y ou wh o prefer t o re ceive PCI in a u ser-friendly d igital format, w e ha ve m ade some e xciting c hanges to our d igital i ssues. T here are n ow ma ny c reative ways w e ca n del iver marketing me ssages t o our r eaders. A nd, a s always, t he d igital i ssue makes i t e asy for y ou t o print articles or share with colleagues. I a lso ha ve s ome cha nges t o r eport regarding ou r e ditorial s taff. E ditor Darlene Br ezinski ha s de cided i t’s time to devote some of her energy into bylining he r o wn t echnical a rticles a nd troubleshooting s ome of t he qu estions PCI receives regularly, in addition to providing s pecial r eporting o n n ew technology a dvancements an d w riting our a nnual Ad ditives Ha ndbook. T o pursue he r g oals, D arlene i s n ow ou r Technical Editor, and Kristin Johansson, who ha s b een PCI’s Ma naging E ditor, has b een p romoted t o E ditor. K ristin has b een w ith B NP Me dia s ince 1 992, and ha s w orked on PCI Ma gazine f or 14 y ears. S he ha s w orked clo sely w ith Darlene a nd ou r c ontributing a uthors, and ha s b ecome v ery k nowledgeable i n the c oatings i ndustry. K ristin w ill n ow be y our po int pe rson f or su bmitting papers and editorial features. Her e-mail address is [email protected]. She will continue to work closely with Associate Editor Ka ren P arker, wh o he ads up our w eekly e -Newsletter, mon thly departments and our annual PCI 25. Please join me in anticipation of another year o f PCI l eadership in t he in dustry. And I h ope t o s ee ma ny of y ou at ou r upcoming C TT t echnical ev ent O ctober 5-6 in Lombard, IL. For more information, visit www.coatingsconference.com.

www.airproducts.com/easy © Air Products and Chemicals, Inc., 2010

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By Donna Campbell | Publisher

SEPTEMBER 2010 | W W W . P C I M A G . C O M

8/18/10 7:44 PM

I NDUSTRY NEWS

Cal Poly Breaks Ground on Coatings Technology Center SAN LUIS OBISPO, CA – The W estern Coatings Technology Center (WCTC) at California Polytechnic State University (Cal Poly) is one step closer to reality, as g round w as br oken on a new $ 2.5 million facility. It will b e named af ter Kenneth N . E dwards, C EO of D unnEdwards P aint, in r ecognition o f hi s efforts in helping to fund the project. The WCTC is designed to expand industry-sponsored r esearch o n campus wh ile p roviding s tate-ofthe-art facilities for students to learn and conduct real-world coatings and polymer-related r esearch w ith fac ulty and industry mentors.

Although part of a state-funded center, the W CTC’s fac ilities a nd e quipment

ACC: Chemicals Management Reform Can Be a Reality ARLINGTON, VA – In testimony before a key House subcommittee, American Chemistry Council President and CEO Cal Dooley urged Congress to take the time to fix recently introduced legislation to r eform t he T oxic Sub stances C ontrol Ac t (T SCA) t o e nsure that it e nhances public safety, preserves the ability of i ndustry to innovate and protects American jobs. “My s imple r equest i s t hat w e r ecognize t hat che micals management is an extremely complex undertaking that affects the e ntire A merican e conomy, a nd t here i s m uch mo re w ork that needs to be done,” Dooley said in prepared remarks provided to the subcommittee. Dooley was one of several witnesses to testify before the Energy and Commerce Committee’s Subcommittee on C ommerce, Trade and Consumer Protection for a he aring on H.R. 5 820 “The Toxic Chemicals Sa fety Ac t of 2 010,” wh ich w as i ntroduced by Re p. Henry Waxman and Rep. Bobby Rush. While Dooley commended Congress for taking on this issue and for using a stakeholder process to gather ideas, he argued that the bill, as drafted, misses the mark. “It c reates ad ditional bu rdens t hat do n ot c ontribute t o a nd, in fac t, d etract f rom m aking adva nces i n s afety, wh ile c oming up sho rt w ith r espect t o p romoting i nnovation a nd p rotecting American jobs,” he said.

Market for Additives and Barrier Coatings for Plastic Packaging to Grow LEATHERHEAD U K – The g lobal market for functional additives and ba rrier c oatings fo r pla stic p ackaging i s s et t o g row by 4 .3 percent i n t he 2 009-2014 p eriod, ac cording t o a new s tudy by Pira International. In 2014, the sector will be worth $752 million compared to $609 million in 2009. From 2009 to 2014, Pira predicts barrier coatings will grow 4.6 p ercent a nnually on a verage, wh ile f unctional ad ditives are expected to expand at a slightly more modest 3.9 percent. The r esulting 4 .3 p ercent c ompound a nnual g rowth rat e of t he combined additives and coatings market is much higher than the predicted growth of t he packaging market. The m arket segments 8

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must be funded entirely by private donations. “Ken has been tireless in his r ole t o g et t he p roject f unded,” said Phil Bailey, Dean of the College of Science and Mathematics. The only such facility on the West Coast, t he new W CTC’s mo dern research f acilities will in clude a p olymer s ynthesis lab oratory, instrumental an alysis c enter, project r esearch lab oratories and t he D unn-Edwards C oatings Formulation L aboratory, na med i n recognition of t he le adership a nd generosity of b oth Kenneth E dwards a nd the Dunn-Edwards Corp.

with the best development prospects are epoxy, SiOx, carbon and PVOH coatings, and anti-fog and antimicrobial additives. The global recession will impact the structure of end-user demand. Sales of ba sic p roducts s uch a s e ssential fo od a nd b everages have remained la rgely u nchanged, but a n umber of p roducts r equiring more sophisticated packaging have suffered a drop in sales. Growing demand for barrier-coated PET bottles will also impact the i ndustry. The ac tivity of la rge r etail cha ins i n d eveloping markets is expected to stimulate the sales of packaged food. Mounting p ressure on bra nd o wners a nd r etailers t o r educe the e nvironmental i mpact of t heir p ackaging i s a nother fac tor influencing the industry. Reducing packaging weight is one likely response, which will drive demand for functional additives.

World Corrosion Organization Granted NGO Status NEW Y ORK, N Y – The W orld C orrosion O rganization (W CO) has b een g ranted n on-governmental o rganization ( NGO) s tatus by t he U nited N ations D epartment of P ublic I nformation N onGovernmental Organization (DPI/NGO) section. In selecting WCO for NGO status, the DPI/NGO recognizes that WCO has the unique capability to make a substantial contribution to t he work of t he DPI. By i ncluding WCO a s a r esource, t he DPI

OBITUARY Industry Loses Sidney Lauren

CLEVELAND – Si dney L auren, E xecutive D irector of C oatings Research Group Inc. (CRGI) from 1972-1985, died at his home in Nashua, NH, on July 13, 2010. Lauren b egan his c areer in th e c oatings in dustry w ith th e C.J. O sborne C o. of Lin den, N J. H e th en j oined th e J ohnsManville Corp. in 1954 and, after a short period with Reichhold Chemicals, re turned t o J ohns-Manville fo r an a dditional 1 0 years, s erving as Chi ef of th e Finish es s ection. Up on re tiring from CRGI and relocating to New England, Lauren worked with California Products Corp. in Cambridge, MA.

SEPTEMBER 2010 | W W W . P C I M A G . C O M

8/18/10 7:51 PM

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The Boomer Retirement Challenge in the Coatings Industry When: November 3 at 2pm ET Where: Online Duration: 60 minutes Cost: FREE Register: http://webinars.pcimag.com Using Actual Industry Examples, You Will Learn To: • Identify and capture critical knowledge before it’s too late; • Identify and use the organizational levers that have maximum impact on succession planning; • Create a workable succession plan for highest-priority needs while managing headcount and budget constraints; • Leverage market events and forces so critical stakeholders buy in to the plan.

I NDUSTRY NEWS acknowledges t he ne ed t o p rovide g reater c orrosion p revention and mitigation guidance to the world. The W CO, ba sed i n New Y ork C ity, i s c omprised of 2 7 of the la rgest c orrosion s ocieties, w ith o ver 5 0,000 i ndividual members worldwide.

SSCT Announces Annual Meeting

Speaker: Nicola James Founder and Managing Partner Thomas Brooke International

Moderator: Kristin Johansson

DAYTONA BE ACH, F L – Re gistration i s n ow op en fo r t he S SCT Annual Me eting, s cheduled fo r S ept. 2 6-29, 2 010, at D aytona Beach, FL. The theme for the meeting is “Racing to New Technology in Coatings.” For details, visit www.ssct.org.

Program for Wood Coatings Congress Now Available HAMPTON, U K – The p rogram fo r PR A I nternational’s W ood Coatings C ongress ha s b een f inalized a nd i s a vailable on t he congress w ebsite, w ww.pra-world.com/woodcoatings7. T he ev ent will take place Oct. 12-13, 2010 in Amsterdam, The Netherlands.

Editor PCI Magazine Sponsored By:

Registration Opens for Particle Summit

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MALVERN, U K – Re gistration i s n ow op en fo r t he i naugural Particle Su mmit, a new ev ent t hat p rovides a fo rum fo r u sers of p article-characterization t echnology. Sp onsored by Ma lvern Instruments, t he P article Su mmit t akes plac e O ct. 2 0-21, 2 010, at t he Cha rles H otel, C ambridge, M A. F or a f ull p rogram a nd registration information, visit www.particlesummit.org. 䡲

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C ALENDAR Meetings, Shows and Educational Programs SEPT. 10 Wood Coatings and Substrate Conference [email protected]

26-29 2010 SSCT Annual Meeting http://ssct.org

28 Ci4000/Ci5000 Weather-Ometer Workshop www.atlas-mts.com

22-24 CEPE Annual Conference & General Assembly www.cepe.org

27-29 CHINACOAT 2010 www.chinacoat.net

29 Fundamentals of Weathering Level I www.atlas-mts.com

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30 Fundamentals of Weathering Level II www.atlas-mts.com

OCT. 3-5 ASC Fall Convention www.ascouncil.org 5-6 Coatings Trends and Technologies www.bnpevents.com/PCI/CTT 11-13 UTECH North America www.utechnorthamerica.nl 11-13 Polyurethanes 2010 Technical Conference www.americanchemistry.com/polyurethane 12-13 Wood Coatings Congress www.pra-world.com/woodcoatings7

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13 Filtration Society’s Annual Conference and Exhibition www.filtsoc.org 13-14 North African Coatings Congress www.coatings-group.com

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12-14 COROSAVE www.corosave.com

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18-20 Future of Pigments www.pigmentmarkets.com 20-21 Particle Summit www.particlesummit.org

NOV. 2-3 Professional Paint Formulation www.pra-world.com/nandl/training/courses 9-11 Fatipec Congress www.vilf.de/fatipec2010 10-12 Spray Finishing Technology Workshop www.owens.edu/workforce_cs/spray2010.pdf 15-18 Paint Technology www.pra-world.com/nandl/training/courses

SEPTEMBER 2010 | W W W . P C I M A G . C O M

8/18/10 3:24 PM

C O M PA N Y NEWS

AkzoNobel Sets Target for China AMSTERDAM, T he N etherlands – AkzoNobel a nnounced t hat it pla ns t o double its current revenue in China within five years. A t arget of $ 3 billion has been set fo r 2 015, w ith Ch ina p oised t o pla y an in tegral r ole in A kzoNobel’s s trategic focus on the world’s growth regions. “The importance of Asia, particularly China, h as lon g b een e mphasized by our c ompany, a nd w e a re c ommitted to ex panding i n t he r egion, a s r ecent investments h ave s hown,” e xplained

AkzoNobel C EO Ha ns Wije rs. “Not on ly is C hina an im portant gr owth e ngine, but it is also rapidly establishing itself as a great center of innovation. It’s moving from m ade in C hina, vi a d eveloped

Dow Microbial Control Opens Academy in Singapore SINGAPORE – D ow M icrobial C ontrol c ustomers i n S outheast Asia, A ustralia a nd New Z ealand w ill ha ve i mproved ac cess t o global technical ex pertise a nd R&D tools fol lowing the launch of Dow M icrobial C ontrol Academy i n Si ngapore. The ac ademy i s a multipurpose educational institution focused on the transmission, expansion and application of microbial-control knowledge. The ac ademy i s d esigned t o p rovide D ow M icrobial C ontrol customers i n t he r egion w ith e asy a nd c ontinuous ac cess to ed ucational o pportunities, r egulatory s upport, te chnical expertise a nd R &D t ools t hrough b oth on line plat forms a nd customized training sessions.

Chemir Offers Custom Synthesis Services MARYLAND HEIGHTS, MO – Chemir Analytical Services now offers custo m sy nthesis se rvices to su pport co ntract resea rch and development for a wide variety of industries. Chemir’s c ustom s ynthesis g roup a ssists t he pla stics, p olymer, coatings, a grochemical a nd s pecialty che mical i ndustries. The company’s organic synthesis capabilities span f rom m illigram to kilogram scale. The t eam’s experience includes specialty and fine chemicals, a grichemicals, pha rmaceutical i ntermediates, a nd new che mical e ntities. Ad ditional s ervices i nclude n ovel r oute design, l iterature sy nthesis, b asic b uilding-block c hemistries, multi-step r eaction s chemes, a nd p rocess r esearch, i ncluding design and scale up.

Brookfield is on the Move in the UK MIDDLEBORO, M A – B rookfield E ngineering ha s a nnounced the ex pansion a nd r elocation of it s U K he adquarters. Wh ile remaining in Harlow, Essex, the new lo cation i s t wice t he s ize of the previous office. Brookfield’s n ew f acility features expanded office space for i nternational s ales a nd marketing e fforts. I t al so h as space to increase the service and repair center and provides plenty of storage for i nstruments a nd spare parts. The lo cation a lso has 14

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in C hina t o inn ovated in C hina, an d we be lieve i t w ill beco me a gl obal powerhouse for science, technology and invention. AkzoNobel wants to make its contribution to that journey.” Speaking d uring t he pre sentation o f the A kzoNobel S cience A wards at t he Shanghai World Expo, Wijers went on to highlight th e n ew €275 m illion Ni ngbo site a nd r ecent i nvestments i n ne w laboratory facilities as prime examples of the company’s ambitions in China.

an a rea d esigned fo r on- site t raining a nd s eminars. The s pace includes a laboratory where customers can immediately apply the theory they have learned in the classroom.

WACKER Supplies Copolymer Dispersions from China Plant MUNICH, Germany/NANJING, China – WACKER began supplying vinyl acetate ethylene (VAE) copolymer dispersions from its plant in Nanjing, China, on July 1. The fully integrated site offers VAE copolymer d ispersions a nd d ispersible p olymer p owders fo r t he construction, coatings, adhesives and other industries. The W ACKER N anjing s ite i s a f ully i ntegrated p roduction complex t hat s erves t he e ntire p roduct l ine f rom VAE c opolymer dispersions to dispersible polymer powders.

Evonik Establishes Carbon Black Company FRANKFURT, Germany – Evonik Industries is reorganizing its carbon black ac tivities. O n J uly 1, E vonik C arbon Black G mbH was fou nded a s a le gally i ndependent m anagement c ompany under t he u mbrella of E vonik I ndustries. The op erational headquarters of the company, currently in Frankfurt, Germany, will move to Hanau-Wolfgang, Germany, on October 1. Jack Clem is CEO of t he new e ntity, and Rainer Wobbe will take over the position of Chief Financial Officer.

Camfil Farr APC Opens Sales and Service Offices JONESBORO, A K – C amfil F arr A ir P ollution C ontrol ( APC), a producer of du st a nd f ume c ollectors, ha s op ened f ive r egional sales and service offices across the country for enhanced support of customers. The new offices are in: Los Angeles, CA; Lincoln, NE; Charlotte, NC; Dayton, OH; and Dallas, TX.

Dow and Mitsui Form Joint Venture MIDLAND, MI – The D ow Chemical Co. (DOW) and Mitsui & Co. Ltd. of Tokyo, Japan, have signed a definitive agreement to form a 5 0/50 m anufacturing joi nt v enture t o c onstruct, o wn a nd operate a new me mbrane ch lor-alkali fac ility lo cated at D ow’s Freeport, T X, i ntegrated m anufacturing c omplex. The fac ility will b e bu ilt u sing D ow’s ch lor-alkali t echnology a nd t akes

SEPTEMBER 2010 | W W W . P C I M A G . C O M

8/18/10 3:54 PM

C O M PA N Y NEWS the plac e of t he p reviously a nnounced Chlorine 7 p roject, wh ich w as a D owonly venture. The new ch lor-alkali fac ility i s expected to begin operations in mid 2013 a nd w ill ha ve a c apacity of approximately 800 kilotons per annum.

Rhodia to Invest in UK and United States PARIS – R hodia pla ns t o i nvest i n t wo of its industrial sites, one in the United States and one in the UK. In t he U K, R hodia pla ns t o c onsolidate surfactants p roduction l ines c urrently at ::: Intelligence in Rheometry

Leeds a nd Ha lifax on a s ingle plat form t o reinforce its long-term competitive position in E urope. The pla n i nvolves a pha sed transfer of assets from Leeds to Halifax. To meet increasing demand from its North A merican cu stomers, R hodia w ill launch a n i nvestment p rogram a t t he company’s U niversity P ark, I L, fac ility to u pgrade an d in crease s urfactant production capacities in the region.

Henkel and BASF Coatings Start Research Joint Venture

Rheometry Focusing on Solutions

DÜSSELDORF/MÜNSTER, G ermany – BASF Coatings GmbH and Henkel AG & C o. K GaA ha ve s igned a joi nt-venture agreement to develop corrosion-protection solutions fo r t he a utomotive i ndustry. Headquartered in D üsseldorf, G ermany, the joi nt venture i s a nticipated t o launch in early 2011. The primary focus of the joint venture will be research and development. It will bring to gether th e uni que c apabilities of b oth c ompanies i n t he a reas of me tal pretreatment and dip coating to develop products and processes that offer greater benefits i n t erms of c ost, p erformance and e nvironmental c ompatibility t han the sta ndard co rrosion-protection processes c urrently u sed w ithin t he automotive industry.

Huber Expands Silica Production Capacity in India ATLANTA – H uber E ngineered Mat erials (HEM), a d ivision of t he J.M. Huber Corp., is e xpanding si lica pro duction ca pacity at it s m anufacturing fac ility i n J hagadia, India. The ex pansion mo re t han double s the c urrent c apacity t o a new rat e of 33,000 metric tons per year. Huber’s J hagadia pla nt p roduces silica a nd s ilicate p roducts fo r a va riety of a pplications, in cluding t oothpaste, coatings a nd p aper. The new c apacity i s designed t o me et t he g rowing d emand for each of t hese applications in India and the s urrounding r egion. The p roject i s expected to be completed by early 2012.

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SEPTEMBER 2010 | W W W . P C I M A G . C O M

MINNEAPOLIS – The V alspar C orp. has a greed t o ac quire A ustralian p aint manufacturer Wa ttyl L imited. Wa ttyl distributes l eading p aint b rands t o r etail customers t hrough home -improvement centers a nd ha rdware ou tlets, a nd t o trade c ustomers t hrough a ne twork of 140 company-owned stores. 䡲

2/3/09 9:55:41 AM

8/18/10 3:54 PM

N AMES IN THE NEWS 䡲 Brookfield E ngineering L aboratories ha s app ointed Thomas Babington Senior Product Development Engineer. He w ill fo cus on new t echnologies a nd w ays t o s treamline manufacturing p rocesses, r educe le ad t imes a nd i mprove product consistency.

䡲 Humberto Juarez ha s j oined Wheelabrator P lus as Re gional Ma nager fo r Mex ico. J uarez ha s o verall r esponsibility fo r m anaging a nd d irecting s ales growth a nd i ndustry b est p ractices fo r a ftermarket sales growth operations.

䡲 DKSH ha s ap pointed Sherman Chau t o t he p osition of

䡲 Anthony M urphy ha s b een ap pointed C ommercial

Local Business Unit Manager, Performance Materials China.

䡲 Patrick Delaney has joined Archway Sales Inc. as a

Babington

䡲 PPG I ndustries’ A erospace b usiness h as a ppointed

Technical Sa les Re presentative fo r t he M idwest r egion. Delaney w ill b e r esponsible fo r g rowing s ales i n N orth Dakota, Minnesota, Wisconsin and parts of Illinois.

Brian Roberson Global Platform Director for Coatings.

䡲 William E. Roller has been promoted to Executive Vice President of Colfax Americas. Roller is responsible for the company’s operations in the Americas, as well as its Global Oil and Gas, and Colfax Defense Solutions organizations.

䡲 Wayne D evonport ha s j oined Arkema E mulsion

Systems i n C ary, N C, a s a G lobal C oatings Re search

Leader. He i s r esponsible fo r t he g lobal r esearch a nd product development strategy for coatings binders used Chau in architectural formulations.

䡲 William H. (Bill) Shropshire has been elected the new CEO of American Chemet Corp. Shropshire will be replacing W. W. Shropshire, who has become Chairman of the Board.

䡲 Thomas W. Handley has been elected a n i ndependent member of H.B. Fuller’s Board of Directors.

䡲 National Coatings Corp. has appointed Brad Stuve as Logistics Manager. He will be responsible for facilitating shipments to and from all of t he company’s U.S. and international customers and suppliers. 䡲

䡲 Michael Huda ha s j oined Reitech C orp. He will help Reitech’s

customers with compliance and regulatory issues as well as adding technical background for support of R&D.

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SEPTEMBER 2010 | W W W . P C I M A G . C O M

8/18/10 4:12 PM

Advances in High-Performance Decorative Topcoats Meeting Stringent VOC Regulations Nationwide

N

ew h igh-performance w aterborne PVDF coatings resins have been developed t hat c an d ramatically ex tend the d ecorative lif etime o f e xterior architectural p aints wh ile ach ieving very lo w V OC lev els, t hus me eting t he mo st s tringent VOC r egulations i n S outhern C alifornia a nd nat ionwide. These PV DF c oatings c an g ive c olor r etention p roperties, wh ich ra nge f rom 2-3 t imes longer (for exotic colors based on s pecialty o rganic p igments), t o a n e ssentially unlimited lif etime w hen p roven in organic p igments a re used. B ecause t hese c oatings a re low-VOC t o b egin w ith, and a re ex tremely lon g la sting, r epainting i s n ot ne eded nearly as often and, therefore, the cumulative amount of VOC g eneration i s s ignificantly r educed, t hus p roviding for a n ex tremely “ green” c oatings s olution. The ad hesion of these coatings to a va riety of substrates, including concrete, is excellent and these coatings exhibit very good mold/mildew resistance and efflorescence resistance, typically b etter t han t op-of-the-line ac rylic s ystems. The se new PV DF c oatings a lso p ossess very low m inimum f ilm formation properties and, therefore, can be applied under a wide range of temperature conditions.

Introduction With ev er-increasing e nvironmental r egulations, t he u se of V OCs i n p aint s ystems i s u nder c onstant p ressure. The paint i ndustry i s c urrently adop ting new t echnologies a nd reformulating its products to meet the deadlines of scheduled VOC le gislation. V OC r egulations of 5 0 g /L i n C alifornia’s South C oast A ir Q uality Ma nagement D istrict ( SCAQMD) are d riving t he r eformulation of oi l-based c oncrete p aints to w ater-based p aints. It i s a cha llenge t o fo rmulators a nd resin producers to bring user-friendly products that meet the performance level that the market demands. There a re va rious t echnologies u sed t o p rovide concrete c oatings, i ncluding ac rylics ( solventborne a nd waterborne), epoxy, urethanes, polyurea and hybrids. In recent years, decorative coatings for concrete have gained

popularity and are primarily based on ac rylic emulsions. However, m any w ater-based c oncrete c oatings o n th e market have VOCs >100 g/L, which can not meet the West Coast 50 g/L VOC requirements. Elastomeric acrylic-type binders c an e asily me et t he V OC r equirements, bu t a re prone to high levels of dirt pick-up. In its technical note on exterior wall coatings for concrete, the U .S. A rmy C orps of E ngineers ha s id entified f ive characteristics that coatings should possess to resist outdoor elements: ultraviolet (UV) stability; breathability; resistance to wind-driven rain; flexibility; and resistance to alkali and fungi.1 This paper will focus on t he performance attributes of a new l ine of f luoropolymer (f luorocarbon) w aterborne hybrid materials based on p oly(vinylidene f luoride) (PVDF) resins,2 which offer a quantum improvement in performance in a ll t hese a reas, i n fo rmulations me eting s tringent West Coast 50 g/L VOC requirements.

New PVDF–Based Hybrid Latex Technology for Concrete Coatings PVDF is a se mi-crystalline f luoropolymer th at is uni que in its ability to be compounded with certain acrylic resins, such a s p oly(methyl met hacrylate).3 This property has been ex ploited for decades i n the metal coating i ndustry; in fact, the original PVDF grade for coatings, Kynar 500® PVDF, ha s b een i n c ontinuous c ommercial p roduction since its introduction by the Pennwalt Company in 1965.4 PVDF-based f luoropolymer c oatings h ave t raditionally been available almost exclusively as solvent-based, factoryapplied finishes on metal substrates. Commercial coatings based on 7 0-80 w t% PV DF/20-30% c ompatible ac rylic are r enowned fo r t heir exc ellent ex terior w eatherability, which is based in large part on the outstanding resistance of PVDF resins to water, to UV radiation, and to other forms of photochemical and environmental attack. When formulated w ith h ighly c olor-stable i norganic p igments, these PV DF-based bi nders r outinely me et t he 1 0 y ear South F lorida “Sup erior” w eathering r equirements fo r the mo st du rable ba ked a rchitectural me tal f inishes.5

By Min Zheng, Ron Partridge and Kurt Wood | Arkema, Inc., King of Prussia, PA 20

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Early tes t p anels b ased o n th is tec hnology, w hich h ave now b een on c ontinuous ex posure i n S outh F lorida fo r as long as 40 years, continue to show minimal color fade and exc ellent s tay-clean p roperties. Th is p erformance is l ikewise n ow c orroborated by l iterally t housands of buildings around the world. In recent years, new developments in PVDF hybrid latex tec hnology h ave m ade i t po ssible to e xtend th e weatherability p erformance of ba ked s olventborne PV DF finishes to low-VOC, waterborne coatings. The new technology p ermits t he u se of PV DF-based c oatings i n field ap plications, a nd on he at-sensitive s ubstrates, wh ich cannot b e ba ked – a ll w ithout t he u se of h igh volumes of solvents.6 To achieve weathering performance comparable to s olvent PV DF-acrylic s ystems, t he w ater-based s ystems use p roprietary tec hnology to c reate a n i ntimate b lend of t he PV DF a nd ac rylic r esins i nside e ach lat ex p article – a p rocess k nown a s h ybridization. The se lat ex p olymer dispersions are anionically stabilized, and can be combined with w ater-based p igment d ispersions a nd fo rmulated with co mmon co atings a dditives d esigned f or w aterborne coatings, similar to the way acrylic latexes are formulated. The mechanical properties and minimum film formation temperature ( MFFT) of t hese d ispersions c an b e adju sted according to particular application needs. For coatings for concrete, an excellent balance of properties can be obtained when th e n eat l atex M FFT is i n th e r ange o f 5 -10 °C.7 Formulations b ased o n th ese m aterials, w ith V OC l evels below 50 g/L, have good elongation at break (>200%) and good low temperature film formation down to 40 °F,8 while maintaining v ery g ood s tay-clean p roperties, an d wi th outstanding color-retention properties.

tolerated th e h ighly a lkaline s urface m uch be tter th an all of t he ac rylic-based p aints. No obv ious w ater-soluble salts are observed for the waterborne PVDF-based coating even w hen th e humidity c hamber e xposure is e xtended to three weeks. An efflorescence combined with cyclic freeze thaw test was also run, where the panels were run 5 cycles under conditions of freeze (16 h at 0 °F), thaw (16 h at 75 °F) and 16 h i n a humidity chamber at 104 °F. I n this more aggressive test, the same results are observed – the PV DF lat ex coating shows much b etter efflorescence resistance t han p remium ac rylic lat ex c oatings at a comparable VOC level of < 50 g/L.

FIGURE 1 | Comparison of efflorescence resistance over Blockaid between topquality acrylic latex paints from South California, and color-matched waterborne PVDF-based paint. (Coatings were exposed in a humidity chamber for 48 h.) Acrylic latex paint 1

Acrylic latex paint 2

FIGURE 2 | Comparison of color-matched blue trade sales paints on fiber cement board, after 2500 h fluorescent cabinet weathering (QUV-B 313). Left: commercial premium acrylic paints; Right: color-matched paint based on PVDF hybrid latex dispersion.

Excellent Efflorescence Resistance

acrylic latex paint 1

acrylic latex paint 2

acrylic latex paint 3

PVDF latex paint

FIGURE 3 | Color change data comparison, as a function of QUV-B exposure time for color-matched blue paints on fiber cement board, between commercial premium acrylic trade sales paints and PVDF hybrid paint.

Delta E

Efflorescence r esistance i s a c ritical r equirement fo r concrete c oatings. Co ncrete s urfaces te nd to be h ighly alkaline when fresh, or when damp or wet from the intrusion of w ater, a nd t hey a re p rone t o e fflorescence. Efflorescence r esistance i s t he abi lity of p aint t o i nhibit the m igration of w ater-soluble s alts f rom a n a lkaline substrate t hrough t he p aint t o ev entually b e d eposited on the paint surface. When dried, the salt is observed as a white discoloration of the paint film. The superior alkali resistance provided by waterborne PVDF coatings is dramatically evident in a representative comparison study comparing low-VOC paint formulations applied t o Blo ckaid™ c ementitious p anels.9 Blo ckaid is a ce mentitious d ry po wder b lock f iller used to cre ate exposure p anels th at s imulate f resh m asonry s urfaces, which ha ve a h igh pH ( ~12). Th is s urface i s id eal fo r testing a coating’s ability to stop efflorescence, surfactant leaching a nd ot her fa ilures br ought on by h ydrolysis of t he c oating a nd t he a lkalinity of t he s ubstrate (i.e. , color fad e, bl istering). F igure 1 sho ws a n ac celerated testing c omparison o n B lockaid b oard, c omparing tw o commercially available premium acrylic latex paints to a color-matched wa terborne P VDF-based pa int. T he c oats of t he d ifferent f ormulations w ere a pplied to sect ions of th e h ighly a lkaline tes t p anels a nd a llowed to d ry seven da ys, a fter wh ich t hey w ere plac ed i n a h umidity chamber for 48 h. The waterborne PVDF-based finish has

Waterborne PVDF-based paint

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10266 commercial acrylic paint 1 10264 commercial acrylic paint 2 10265 commercial acrylic paint 3 0

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Excellent Color Fade and Chalk Resistance Over Fiber Cement

Delta E*

and fo r t he new w ater-based lat ex materials, w hen c omparable lev els ent stain comparison on primed fiber cement of PVDF resin are used. Another c ritical p erformance panels: Left: premium acrylic stain; Right: PVDF Figure 2 sho ws t he c olor fad e requirement fo r ex terior c oncrete hybrid-based stain. comparison of p remium ac rylic coatings is d urability – th at is , latex c oatings a nd a c olorthe r etention o f p roperties a fter matched P VDF wa ter-based exposure. D ecorative d urability coating o ver p rimed f iber c ement refers t o a p aint’s abi lity t o r etain panels, a fter 2 500 h ex posure its ae sthetic ap pearance on with ve ry a ggressive U VB-313 exposure t o t he e lements. O utdoor bulb radiation. Figure 3 sho ws the exposure will b reak d own alm ost color cha nge dat a a s a f unction of all coatings, causing them to chalk, the cabinet ex posure t ime. Wit hin fade a nd d iscolor. For c onventional 600 h, t he ac rylic c ontrols ha ve paints, c olor fad e due t o cha lking significantly c hanged c olor. F or occurs when the polymers holding the c olor-matched w ater-based the paint t ogether – a lso called t he PVDF h ybrid co ating, t he co lor binder – a re degraded by t he action remains a lmost u nchanged, ev en of U V l ight, w ater, o xygen, e tc. after 2500 h exposure. In the field, Acrylic p aints, l ike ot her k inds of the c olor fad e fo r da rker p aints i s paints ( e.g., polyesters, u rethanes), typically associated with chalking. can show significant levels of color fade and chalking after In t he U VB-313 c abinet a s w ell, t he ac rylic p aints w ere 5-7 years of F lorida ex posure. The s uperior weatherability found t o cha lk d ramatically, whe reas t he PV DF h ybrid of coatings made with high levels of PVDF resins is based on paint did not show chalking. the ability of the fluorocarbon resin to resist ultraviolet rays, Figures 4 a nd 5 sho w a nother ac celerated t esting water, t emperature ex tremes, o xygen a nd at mospheric comparison on f iber c ement b oards, c omparing a s emipollutants. A s a r esult, s imilar w eathering p erformance transparent ac rylic s tain t o a c olor-matched w aterborne is seen both for the traditional baked solvent PVDF paints, PVDF-based s tain. O n t he le ft i s a c ommercial p remium acrylic s tain, a nd on t he r ight i s a PV DF h ybrid-based stain. A fter 60 00 h QU V-B (313 n m) ex posure, t he t otal FIGURE 5 | Color change data as function of QUV-B exposure time (313 nm) for color cha nge fo r t he ac rylic s ample ( left) w as me asured color-matched semi-transparent stain on primed fiber cement panels. to b e ab out fou r t imes h igher t han fo r t he PV DF hybrid18 based paint (right). 16 14 12 10 8 6 4 2 0

FIGURE 4 | 6000 h QUV-B (313 nm) semi-transpar-

Water Pick-Up Resistance and Breathability of PVDF Hybrid-Based Coatings

0

1000

2000 3000 4000 5000 6000 Hours UV-B Fluorescent Cabinet Exposure

7000

9684 premium acrylic stain 9685 PVDF hybrid-based stain

Water Weight Gain %

FIGURE 6 | Comparison of water pickup curves (% weight gain of coating from continuous water immersion), trade sales-type latex paint formulations. 25%

PVDF hybrid-based paint

20%

Commercial acrylic latex paint 1

15% 10%

Commercial acrylic latex paint 2

5% 0% 0

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Commercial acrylic latex paint 3 Commercial acrylic latex paint 4

For many applications on breathable substrates like concrete, it i s i mportant fo r t he c oating t o r esist o r repel l iquid w ater a nd y et b e p ermeable t o w ater vap or. Exterior concrete coatings should be able to withstand penetration by w ind-driven ra in, b oth t o p revent w ater from entering t he c oncrete a nd t o prevent c ontaminants such as airborne particulates and acids from being carried i nto t he s ubstrate w ith w ater. At t he s ame t ime, entrapped w ater shou ld b e able t o le ave t he s ubstrate, since entrapped moisture can lead to damage from cyclic freezing and thawing, and can result in coating failure. Fluoropolymer resins like PVDF hybrid products are inherently hydrophobic, and when compared with acrylics show much lower water pick up. The abi lity of t he topcoat not to absorb water will improve the chances of keeping the substrates d ry. F igure 6 sho ws t he w ater uptake b ehavior for a PV DF h ybrid lat ex d ispersion p aint fo rmulation compared t o s everal c ommercial t rade s ales lat ex p aints. The s teady s tate w ater ab sorption lev els fo r t he PV DF hybrid latex dispersion paint are in the 1-3 wt% range, very low c ompared t o t he a ll-acrylic lat ex p aints, wh ich ha ve long-term water pickup values in the 8-20 wt% range. The br eathability ( water vap or p ermeability) of concrete c oatings c an v ary wi dely d epending o n t he specific c omposition a nd m aterial p roportions of t he

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Advances in High-Performance Decorative Topcoats

Dirt Pick-Up and Mildew Resistance of PVDF Hybrid-Based Coatings

FIGURE 7 | Water permeation rate (ASTM D 1653) for a series of PVDF hybrid-based Water Permeation Rate (perm)

paints, as a function of pigment volume concentration (PVC). 80 60 40 20 0 0

5

10

15

20

25

30

35

%PVC

coating p roduct. A c oating w ith a lo wer p igment-tobinder rat io (t ypically a g lossy c oating) t ends t o b e le ss vapor p ermeable t han a c oating w ith a h igher p igmentto-binder rat io (t ypically m atte o r f lat c oating), a nd a solventborne coating will tend to be less permeable than a w aterborne c oating w ith t he s ame p igment-to-binder ratio and gloss level. In addition, the different polymers or resins used as binders in coatings have different inherent permeability va lues, a nd t hus a ffect t he br eathability of t he c oating p roduct i n wh ich t hey a re u sed. We ha ve found t hat fo r PV DF-acrylic lat ex d ispersion c oatings, it is po ssible to t une th e w ater v apor pe rmeation r ate over a la rge ra nge, s imply by adju sting t he p igment volume c oncentration (PV C) of t he c oating. F igure 7 shows one exa mple of t his. F or t he PV DF w aterborne coatings, w ith i ncreasing t he PV C lev el f rom 1 2% t o 30%, the permeability varies from 10 to 80 perms while the eq uilibrium w ater p ickup f or th is se ries is n early unchanged ac ross t he ra nge of PV C va lues t ested, i n t he range of 1 .3-2.5 w t% (n ot sho wn). The refore, d epending on t he r equirements of t he ap plication, t he p aint’s w ater vapor t ransmission p roperties c an b e i ndependently adjusted across a wide range, by varying the pigmentation level, while still keeping a very low water pickup.

Coatings based upon PVDF resins show very good resistance to dirt pick-up, and to the growth of mildew and other biological organisms, as demonstrated both in accelerated lab tests and also in real life field performance. Figure 8 sho ws a s ide-by-side c omparison of PV DF hybrid-based wh ite c oating a nd a c onventional ac rylic white c oating a fter 8 mont hs i n F lorida s outh fac ing 5° a ngle ex posure. The se p articular fo rmulations w ere made w ithout m ildewcides, s o a s n ot t o ob scure t he effect of t he r esin bi nder on t hese i mportant p roperties. The p anel on t he le ft, m ade w ith a PV DF h ybrid lat ex dispersion fo rmulation, ha s s tayed v ery cle an wh ile t he panel on t he r ight, wh ich i s a c onventional ac rylic r oof coating fo rmulation ( but w ithout ad ded bio cide), sho ws substantial dirt pick-up and biological growth. A lab oratory t est of d irt p ick-up r esistance w as a lso run. I n t his t est, t he p aints w ere d ried fo r one w eek, and t hen a n i ron o xide p igment sl urry w as ap plied a nd allowed t o d ry 3 h. The d ry i ron o xide w as t hen r insed off t he p aint w ith w ater a nd l ight w iping w ith a p iece of wet che esecloth. The p anels w ere cle aned u ntil n o mo re iron o xide w as b eing p icked up by t he che esecloth, t hen the c olor d ifference ( Delta E ) w as r ead b etween t he a rea coated with the iron oxide slurry and a c ontrol area with no i ron oxide slurry. I n t his t est, la rger D elta E n umbers indicate that more iron oxide pigment is left on the surface of the paint. In this laboratory dirt pick-up resistance test shown i n F igure 9 , t he PV DF h ybrid-based p aint sho ws significant lo wer D elta E n umber t han a ll t he ac rylicbased wh ite p aints, a gain h ighlighting t he “ stay-clean” properties of these fluorocarbon coatings. The “stay-clean” property is particularly important for concrete roof coatings. The exc ellent dirt pick-up resistance of PVDF hybrid latex coatings helps to maintain the highest level of s olar r eflectivity of r oof c oatings. By d ramatically reducing s urface r oofing t emperatures, bu ilding a ir conditioning costs are reduced.10 The poor dirt retention over



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FIGURE 8 | Elastomeric roof coating formulations (without added biocide), exposed 8 months in South Florida, South 5° exposure, July 2007 through February 2008. Left: Formulation based on PVDF hybrid latex dispersion; Right: conventional acrylic control formulation.

time of ac rylic lat ex c oatings c an le ad t o a significant decline in total solar reflectance. For s ome wh ite ac rylic-based c oatings i n the f ield, w ith a n i nitial T SR of o ver 70%, drops i n t he T SR (t otal s olar r eflectance) down to as low as 20-30% in 2-3 years have been reported.11 The new PVDF hybrid waterborne technology can offer very high TSR retention. The test panels have a very high i nitial TSR of a round 0.80, a nd more importantly r etain o ver 95% o f t his v alue after six years South Florida exposure.6

Conclusion The d evelopment of PV DF h ybrid lat ex technology now a llows t he c oatings industry to take advantage of the properties of the PVDF fluoropolymer for f ield a nd fac tory-applied c oatings on c oncrete a nd ot her c ementitious substrates. A g rade w ith a n M FFT va lue in t he 5 -10 °C ra nge c an b e fo rmulated into hi gh-performing, l ow-VOC p aints meeting s tringent S outhern C alifornia VOC r egulations. B ecause t hese c oatings are lo w V OC t o b egin w ith, a nd a re extremely l ong-lasting, repa inting i s n ot needed nearly as often. With a longer service l ife, t he c umulative a mount of VOC g eneration i s r educed ev en mo re, thus p roviding fo r a n ex tremely “ green” coatings s olution. The abi lity of PV DFbased coatings to resist UV degradation, water a nd che mical at tack, a llows these c oatings t o m ore e asily r esist dirt , staining an d mil dew/algae gr owth. High-performance, lo w-VOC w ater-based coatings based on PV DF latex dispersions open u p n ew opp ortunities t o f urther extend the longevity, and performance, of concrete buildings and structures. 䡲

Bring on all your bright ideas. Our global UV/EB resources help make them winners. Wherever you need UV/EB support, Sartomer is there for you – in the Americas, Europe, and Asia. We deliver leading-edge UV/EB technology and responsive local manufacturing. We can also help with the complexities of product/country registration issues. Our in-depth expertise and high-performance specialty chemicals will help you bring all your ideas to life and get them to market – fast. Now you can take on any job – plastic and metal coatings, inks, display, automotive, adhesives – or even a totally new application. Rely on us from initial concept to final delivery. Formulators choose Sartomer for UV/EB innovation and consistent quality… batch after batch. Our broad line of more than 700 monomers and oligomers leads the world. If your formulation calls for something unique, we tailor a custom fit. Contact us now for the help you want to beat the competition. Call 800-SARTOMER, 610-363-4100 or visit www.sartomer.com.

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FIGURE 9 | Dirt pick-up resistance comparison tested with iron oxide slurry between commercial premium acrylic white paints and PVDF hybrid white paint. 30.00 25.04

25.00

Delta E

20.00 15.00 10.00

7.28 4.33

5.00

4.88 0.56

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commercial acrylic latex paint 1 commercial acrylic latex paint 2 commercial acrylic latex paint 3 commercial acrylic latex paint 4 PVDF hybrid-based paint

References 1

2

3

U.S. Army Corps of Engineers, Engineer Research and Development Center, REMR Technical Note CS-MR-7.4: Selection of Concrete Exterior Wall Coatings, accessed at http:www. wes.army.mil/REMR. These PV DF-acrylic l atex d ispersions a re m arketed u nder the KYNAR Aquatec® trademark of Arkema Inc. Gaboury, S.R. and Wood, K.A “Tailoring Coating Properties Through C ontrol of PV DF C opolymer P hase B ehavior”, Surface Coatings I nternational Part B, 85, B4, (2002) 295-

300; B ernstein, R. E.; Cruz, C A .; Paul, D. R.; Barlow, J. W. Macromolecules 1977, Vol. 10, 681. 4 Humphrey, J . S. ; D rujon, X . P olymeric M aterials Encyclopedia; CRC Press, Inc., 1996, Vol. 11, 8591; Iezzi, R.A., “Fluoropolymer Coatings for Architectural Applications”, in Modern Fluoropolymers (Wiley, 1997), p. 14. 5 AAMA 2605-5 specification for spray coatings on aluminum substrates, a vailable f rom t he A merican A rchitectural Manufacturers A ssociation, S chaumburg, I L, w ww. aamanet.org. 6 Gupta, R .; W ood, K . No vel F luoropolymer-based E mulsion Technology: St riving fo r “ Green” C oatings. Paint a nd Coatings Industry 2007, 7, 70-80. 7 A product of th is t ype is now under development, w ith the tradename KYNAR Aquatec® FMA-7 of Arkema Inc. 8 ASTM D 7 306 St andard P ractice fo r T esting L ow Temperature F ilm-Formation of L atex P aints b y Vi sual Observation. 9 Trademark of ICI Paints. 10 Zheng, M.; Wood, K.A. St rategies for B oosting t he I nfrared Reflectance of C oatings fo r C ool Ro of Ap plications. Proceedings o f Fu turecoat! C onference (F SCT, Octo ber 2006, New Orleans, LA), abridged version “Hot Solutions for Cool Roofs” in Finishing Today 83(2) February 2007, 34-39. 11 S ee http://www.ersystems.com/news_presentations.htm, 2006 Presentation on Advanced Sustainable Roof Systems.

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Characterization of the Surface Mechanical P

Polymeric Surface

T

he mechanical properties of polymeric coatings a re of ten o verlooked b ecause researchers a re n ot a ware of ho w mo dern i nstrumentation c an a id t hem i n understanding how a particular product may s urvive i n s ervice c onditions. I n m any ap plications the two main considerations are aesthetics and durability, both of wh ich c an b e d irectly r elated t o t he me chanical properties of t he base material. For exa mple, the du rability of a paint will depend on its hardness, elastic modulus, scratch resistance, abrasion resistance and on how well it adheres to its substrate. The ae sthetic quality of t he paint surface will depend on its ability to resist surface scratches and d eformations, wh ich w ill d iffract l ight a nd c ause it t o lo se it s g lossy ap pearance. Th is p aper p resents t he instrumentation met hods r equired t o me asure ac curate mechanical properties of soft polymeric coating materials that are commonly used in coatings.

Introduction Single-probe t esting d evices have b een a round fo r m any years but o nly recently have instruments been developed with a r esolution a dequate f or a ccurately m easuring the me chanical p roperties of p olymeric c oatings. The challenge of coatings, as opposed to bulk polymers, is that the test probe (or indenter) must not penetrate too deeply into t he c oating, ot herwise t he me asured me chanical property w ill n ot r epresent t he c oating on ly, bu t w ill be a c omposite p roperty of t he c oating a nd s ubstrate. In ad dition, p olymeric m aterials a re v ery s oft a nd s o a large i ndenter d isplacement w ill c orrespond t o a v ery small applied load. Th is means t hat t he i nstrument u sed needs to have a very high load resolution and should be feedback-controlled to minimize the effects of creep. Previous w ork1-3 ha s sho wn t hat t he s ingle-probe method c an p rovide s ignificant i nformation ab out t he failure mo des of c ertain p olymers. M uch w ork ha s a lso been done on automotive clearcoats,4-7 wh ich is a p erfect example of whe re b oth ae sthetic qua lities a nd du rability are p aramount t o t he e nd-use ap plication. I ndustrial automotive p olymer va rnishes a re of ten ex posed t o harsh e nvironmental c onditions y et t hey a re ex pected to maintain a high-gloss finish for at least five years. In the a utomotive p olymer f ield, one of ten he ars t he t erms “mar resistance” and “scratch resistance” used to describe the p roperties of a p articular m aterial. Ma r r esistance characterizes t he abi lity of t he c oating t o r esist da mage by light abrasion. The difference between mar and scratch resistance is that mar is related only to the relatively f ine surface scratches that spoil the appearance of the coating.

Mar r esistance d epends on a c omplex interplay b etween v iscoelastic o r thermal r ecovery, y ield o r pla stic flow, a nd f racture. P olymers are cha llenging b ecause t hey exhibit a ra nge of me chanical properties from near liquid through r ubbery materials to brittle solids. The mechanical properties a re r ate a nd temperature d ependent, and vi scoelastic r ecovery can ca use def ormed material t o c hange with ti me. I n th e c ase of a utomotive cle arcoat varnishes, for exa mple, the c ar i s m anufactured with a very good quality gloss f inish. The c ar i s taken to a n a utomatic c ar wash a nd c leaned. B ecause many c ar w ashes ha ve i nsufficient s oap a nd t he r insing is too short, particles of d irt present in the water actually cause surface scratching of t he car body. These scratches are n ot v isible t o t he h uman ey e (t he h uman ey e c an resolve scratches with a width of about 10 µm or greater), but whe n t here a re m any of t hem, t hey r educe t he g loss of t he s urface a nd m ake it lo ok du ll. Mo dern automotive clearcoats a re d esigned s o t hat s mall s urface s cratches actually “heal” over a time period of a few hours, this being caused by complete viscoelastic recovery of the polymer. The same principle is also used in many types of aesthetic c oatings whe re s urface s cratches would r educe the ap pearance, e. g., na il va rnish, c onsumer e lectronic device c oatings, p aints, e tc. I n o rder t o s imulate s uch small s cratches a nd ac tually g et a qua ntitative va lue fo r viscoelastic recovery at this scale requires instrumentation with s ub-nanometer d epth r esolution a nd na no-Newton load resolution.

Methodologies The t hree mo st c ommon t est me thods fo r a ssessing the me chanical p roperties of p olymeric c oatings a re indentation (t o me asure ha rdness a nd e lastic mo dulus), scratch t esting (t o me asure c oating i ntegrity, s cratch resistance a nd v iscoelastic p roperties) a nd w ear t esting (to me asure f rictional p roperties a nd w ear rat e). The principle of e ach me thod i s ex plained a nd it s p articular importance to polymers.

By Dr. Nicholas X. Randall | CSM Instruments, Needham, MA 28

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028 CSM FT.indd 28

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Properties of Paints and

Coatings

plastic d eformation. Bec ause po lymers te nd to be m uch softer t han ot her e ngineering m aterials, t he ap plied load s are commonly i n the m illi-Newton ra nge a nd penetration depths i n t he na nometer ra nge. The ba sic p rinciple of a n instrumented indenter (or Nano Hardness Tester) is shown in Figure 1a,where the load is applied by a load cell and the resultant displacement is measured by a c apacitive sensor. A typical load-depth curve is displayed in Figure 1b.

S cratch Testing The scratch test is similar to instrumented indentation, except th at th e s ample is d isplaced d uring a pplication of t he load. By c areful c ontrol of t he i nstrument, t his allows t he u ser t o m ake a c onstant load, p rogressive load o r i ncremental load s cratch w ith a p redefined length an d l oading r ate. S tate-of-the-art in struments have active force feedback control to ensure that the load is correctly applied even over curved or rough surfaces. D uring s cratching t he f rictional fo rce (o r tangential fo rce) b etween t he i ndenter a nd s ample surface is recorded and an acoustic emission sensor captures a ny n oise th at m ight be p roduced w hen th e tested co ating sta rts cr acking ( this i s m ost usef ul f or

FIGURE 1 | Principle of instrumented indentation (a) and typical example of a loaddepth curve (b) from which the hardness and elastic modulus can be calculated. Normal load

(a)

(b)

Load cell Capacitive displacement sensor

Indenter

Penetration Depth (µm)

Sample surface

FIGURE 2 | Principle of the scratch test (a) and typical example of test data (b) from which the critical failure point of the coating can be measured. In this case there is a significant jump in both the frictional force and acoustic emission signals, which correlates to delamination of the coating.

Tangential force

Sample motion

Critical Load (Lc) 6 5 4 3 2 1 0

0

2 4 6 8 Normal Load

PA I N T & C O A T I N G S I N D U S T R Y

028 CSM FT.indd 29

10

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Acoustic Emission

Normal load Acoustic emission Scratching stylus detector

Tangential Force

Most p eople ar e f amiliar wi th conventional h ardness t esting, where a n i ndenter o f k nown geometry (u sually B rinell, Rockwell, Vi ckers or Knoop) is pushed into the sample a nd t he s ize of t he resulting i mpression i s measured t hrough a n optical m icroscope. The hardness i s me asured by d ividing t he ap plied load by t he c alculated residual co ntact a rea. This w orks w ell fo r bulk m aterials whe re the ap plied load s a re generally h igh a nd the r esidual i mprint is e asily l ocated un der the op tical m icroscope. However, with soft polymeric materials, their viscoelastic properties c ause t he r esidual i mprint t o r ecover a fter loading and it is therefore very difficult to get meaningful data. Ad ditional p roblems a rise whe n one w ants t o measure the hardness of a t hin polymer film without any effect from the substrate on which it is deposited. Because of t he a forementioned l imitations of conventional in dentation m ethods, in strumented indentation ha s b een d eveloped o ver t he la st few y ears. The me thodology i s t he s ame, i.e. , a n i ndenter p ressed into a s urface, bu t w ith t he instrumented tec hnique the load a nd d epth of t he i ndenter a re c ontinuously monitored o ver t he e ntire load ing-unloading c ycle. Th is provides a load -depth c urve, wh ich i s a “ fingerprint” of the m echanical p roperties o f th e tes ted m aterial, f rom which the hardness and elastic modulus can be calculated (the mo dulus i s c omputed f rom t he i nitial t angent of t he unloading c urve). Th is me ans t hat i maging t he r esidual imprint i s n o lon ger a r equirement of t he me thod a nd thus very low loads can be applied to very small material volumes t o g ive qua ntitative p roperty va lues. B ecause instrumented i ndentation i nstruments a re c ompletely software c ontrolled, t hey a re able t o ma ke s ingle-cycle, multicycle a nd D ynamic Me chanical A nalysis ( DMA) measurements a nd t he load ing/unloading rat es c an be ac curately c ontrolled. I nstrumented i ndentation i s covered in ISO 14577 and ASTM E 2546-07. In t he c ase of p olymeric m aterials t hat a re v ery t imedependent, s ignificant a dditional inf ormation c an b e gained concerning the materials’ response to elastic and

Normal Force (N)

Indentation Testing

29

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Characterization of the Surface Mechanical Properties of Paints and Polymeric Surface Coatings

brittle c oatings, s uch a s a w eather e mbrittled ex terior varnish). The basic principle of a scratch tester is shown in Figure 2, as well as a typical result. Most interesting for polymers is that such instruments also p rovide p re-scan a nd p ost-scan p rofiling of t he surface. The pre-scan consists of scanning the indenter over the surface with the lowest possible applied load to give t he t opographical p rofile. The s cratch t est it self i s then l aunched a long th e s ame p ath d uring w hich th e penetration dept h (P D ) i s me asured. A fter t he s cratch test is c ompleted, th e i ndenter is th en sc anned b ack

FIGURE 3 | Principle of the pin-on-disk wear test (a) and typical example of test data (b) from which the friction coefficient between the coating and the static partner (usually a ball) can be assessed. A significant change in friction corresponds to the ball wearing through the coating and thus gives a measure of the lifetime of the coating. (a)

(b)

Weight: 1N, 2N, 5N and 10N

0.3

Elastic arm

Friction force sensor

Friction Coef.

Pin, ball holders Rotating disk or cap for liquid testing

Wear track

Sliding Life

Time

FIGURE 4 | Single-cycle nanoindentation on a PMMA coating, (a) which had a maximum applied load of 5 mN and a 20 second pause at max load. The creep of this polymer at max load was 67 nm at a depth of 963 nm. A sinus-mode indentation is shown in (b) with max load 5 mN, sinus frequency 1 Hz and amplitude 1 mN. 6.0

5.0

(a)

4.8

(b)

4.0

H = 270 MPa E = 4.2 GPa

3.6

3.0

2.4

2.0

1.2

1.0

00mN 0.0 nm

240.0

480.0

720.0

960.0

00mN 1200.0 0.0 nm

— Normal force (Fn)

W ear Testing

160.0

320.0

480.0

640.0

800.0

— Penetration depth (Pd)

40.0 0.300 (b) 35.0 0.250 30.0 E’ 0.200 25.0 20.0 0.150 15.0 0.100 E’ ’ 10.0 0.050 5.0 0.0 0.000 60.0 80.0 100.0 120.0 140.0 160.0 180.0

Depth (nm)

30

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028 CSM FT.indd 30

Loss Modulus, E'' (GPa)

Storage Modulus, E' (GPa)

FIGURE 5 | Heating stage (a) mounted on a CSM Instruments Micro Hardness Tester for investigating polymer viscoelasticity at temperatures over the range -35 ºC – 450 ºC. Sinus mode results on a coating (b) show the evolution of storage and loss moduli with depth in the material at a measurement temperature of 35 ºC. (a)

along t he s cratch w ith t he s ame lo w ap plied load a s for the pre-scan. This f inal post-scan gives the residual depth (R D ), wh ich i s a me asure of t he v iscoelastic relaxation of the material. In order to take into account the original sample surface, the true PD and RD data sets are r ecalculated a fter ha ving s ubtracted t he p re-scan. If viscoelasticity is to be investigated as a function of time then the post-scan can be performed at predefined time periods after the scratch test. In s cratch t esting, t he i ndenters u sed t end t o b e spherical i n g eometry, a nd va rious d ifferent s izes c an be u sed t o i ncrease/decrease t he c ontact p ressure a nd therefore th e se verity o f th e sc ratch. W ith r egard to aesthetic p olymer c oatings, t he r elationship b etween scratch m orphology an d vi sibility i s v ery c omplex since m any va riables a re i nvolved i ncluding ba secoat color, li ghting, o rientation, d uration o f in spection, psychological factors, as well as size and type of damage. Some previous work has focused on evaluation of mar and scratching by optical characterization methods,8 wh ilst others ha ve i nvestigated t he e ffect of s cratches on u ser perception b y u sing s tatistical m eans.9 W ith th e l atter, the m ain obje ctive w as t o ad dress s everal f undamental questions such as what are the types (plastic or fracture) and sizes of scratches that can be seen by the human eye at a g iven c ondition. I n t his c ase, a ra nge of c onstant load s cratches w as m ade u sing load s b elow a nd ab ove the f racture t hreshold fo r t hat p articular p olymer. A selection of t ypical users of t he product was then shown the t est p anel fo r d ifferent le ngths of t ime a nd a sked t o count a ll v isible s cratches. C onditions w ere cho sen t o simulate t he w orst c ase s cenario fo r v isibility: a blac k basecoat a nd l ight i ntensity e quivalent t o t he m idday sun. Scratch testing on polymers is specifically covered by I SO 1 9252 a nd A STM D 7 187, wh ich i s fo cused on “Test me thod fo r me asuring s cratch/mar b ehavior of paint coatings by nanoscratching” The p in-on-disk w ear t est i s p erformed u sing a n instrument k nown a s a Tribometer, a s chematic of wh ich is shown in Figure 3a. The sample is mounted on a chuck that c an b e r otated at a p redetermined s peed. A ba ll or ot her s tatic p artner i s mou nted i n c ontact w ith t he rotating sample via an elastic arm that can move laterally and t herefore me asure t he f riction b etween s ample a nd ball w ith a s ensor. The dat a ac quisition s ystem r ecords the f rictional for ce a s a f unction of t ime or n umber of revolutions, a lthough i t is o ften r ecalculated s o th at actual f riction c oefficient ( µ) i s d isplayed on t he s ame axes. A t ypical exa mple i s sho wn i n F igure 3 b. O nce a test is c omplete, th e a ctual w ear r ate o f th e s ample a nd partner c an b e c alculated by one of t wo w ays: t he f irst is t o u se a p rofilometer t o me asure t he p rofile ac ross t he wear t rack a nd c alculating t he s ectional a rea r emoved. If th is is m ultiplied b y th e w ear t rack c ircumference then t he v olume of m aterial r emoved c an b e c alculated, and t hus t he a mount r emoved a s a f unction of t ime, the wear rate (usually quoted in mm3/N/m) fou nd. The second m ethod is to w eigh th e s ample be fore a nd a fter testing w ith a h ighly ac curate ba lance a nd c alculate

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Characterization of the Surface Mechanical Properties of Paints and Polymeric Surface Coatings

the m aterial r emoved, a lthough th is m ethod is m ore problematic b ecause t he d ebris p roduced du ring t he t est must b e completely removed t o prevent significant error. This is o ften d ifficult w ith po lymers bec ause th e d ebris tends to stick to both surfaces. Most Tribometers now offer both rotation of the sample and/or linear reciprocating movement of t he s ample. The choic e w ill d epend on t he end use application. Useful standards for this test include ASTM G 99, ASTM G 133 and DIN 50324.

FIGURE 6 | Typical progressive load scratch tests on polymer coatings: (a) PVC-based appliance hardcoat finish; (b) silicone cell-phone finish; (c) automotive varnish topcoat. Note the distinct differences between (a) which is hard and brittle and (c) which is soft and ruptures, with (b) being a mixture of the other two. (a)

(b)

(c)

FIGURE 7 | Nano scratch test results for progressive load (0 – 20 mN) measurements on two different automotive topcoats (A and B). The penetration depth (Pd) during scratching and the residual depth (Rd) after scratching are presented for both samples. Optical micrographs show the onset of plastic deformation (left) and the extent of deformation at maximum load (right). Note that sample A has far greater viscoelastic recovery than sample B. 20

0

Rd-A

16 Rd-B

12

20µm

20µm

1.5 3

Depth (µm)

Normal Force (mN)

20µm

8

Pd-B

4.5

4

Pd-A

6

0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

2

20µm

7.5

Scratch Length (mm)

32

0.7 0.6

(a)

0.5

R2 =0.8085 I

D

B F

0.4 0.3 0.2 45

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028 CSM FT.indd 32

A

HE C 55 65 75 85 95 Gloss Retention (%)

Permanent Deformation at 5 mN (µm)

Residual Depth (µm) at 5 mN

FIGURE 8 | Summarized scratch test data for a series of automotive topcoats. In (a) the residual scratch depth (corresponding to an applied load of 5 mN) is shown as a function of gloss retention as measured with a glossmeter. In (b) the permanent deformation at 5 mN has b een plotted as a function of fracture load; this example shows the samples whose scratch resistance improves after post ageing (weathering). 0.6 Better (b) D 0.55 A 0.5 I B E 0.45 J G 0.4 H 0.35 Better 0.3 4.00 5.00 6.00 7.00 8.00 9.00 10.00 Normal Force at Fracture (mN)

Applications Indentation Testing The b eauty o f in strumented n anoindentation i s t hat the loading and unloading portions of the test cycle are fully user-programmable, as well as any intermediate portions such a s a p ause at a c ertain load o r depth. A standard t est on a p olymer m ight c onsist of a load unload c ycle w ith a p ause at t he m aximum ap plied load to investigate the creep properties of the material. A t ypical exa mple of a t est on a PM MA c oating i s shown in Figure 4a where the maximum load is 5 m N with a 20 sec pause before unloading. From this curve, values of ha rdness ( H) a nd e lastic mo dulus ( E) ha ve been calculated as 270 MPa and 4.2 GPa respectively. The creep of the material at maximum load was 67 nm at a depth of 963 nm. In order to obtain further mechanical properties of this po lymer th at r elate to i ts v iscoelasticity, i t is bes t to use DM A o r a dy namic i ndentation t est p rocedure. A small a mplitude fo rce o scillation i s s uperimposed ont o the ap plied load s ignal a nd t he r esultant d isplacement amplitude i s me asured. F rom t he pha se sh ift b etween force a nd d isplacement, s everal me chanical p roperties (including H a nd E ) c an b e me asured a s a c ontinuous function of depth in a single indentation. An example of a dynamic test result on t he same PMMA coating is shown in F igure 4 b whe re a s inus f requency of 1 H z ha s b een used with amplitude 1 mN. Viscoelastic polymers will show some elastic (energy storage) a nd s ome v iscous ( energy lo ss) b ehavior. The s tress i nduced i n s uch a m aterial s ubjected t o a sinusoidal strain will be out of phase by a certain angle. The magnitudes of t he elastic response and the viscous response a re t herefore u sed t o d efine t he s torage ( E’) and lo ss ( E’’) mo duli. The s torage mo dulus c an b e regarded a s b eing nearly e qual t o t he s tress r elaxation modulus. The loss modulus tends to be small in regions where t he s torage mo dulus sho ws a plat eau bu t w ill increase whe n a t ransition o ccurs. Th is ap proach assumes l inear v iscoelastic b ehavior, i.e. , t he s torage and lo ss mo duli a re i ndependent of t he i mposed s train amplitude (t his a ssumption i s va lid fo r mo st p olymers provided t hat t he s train a mplitude do es n ot exc eed approximatey 0.5 – 1.0 %). Control of t he s ample t emperature i s c rucial whe n measuring s torage a nd lo ss mo duli a s t hey a re b oth temperature d ependent. Mo dern i nstruments of ten ha ve optional he ating/cooling mo dules t o a llow ac curate control of t he s ample t emperature ( Figure 5 a). F or example, a t est m ight c onsist of m aintaining c onstant frequency wh ile t he t emperature i s ra mped o ver t he region o f i nterest. I n th is w ay, s pecific t ransitions c an be mon itored, e. g., whe re t he p olymer cha nges f rom a hard c ondition t o a v iscous/rubbery c ondition (t he glass transition temperature, Tg). Dynamic i ndentation t esting c an a lso b e u sed fo r investigating c reep a nd fat igue p roperties. I n a t ypical dynamic c reep t est, t he i ndenter i s o scillated at a predetermined a mplitude a nd f requency du ring t he holding segment of t he load-depth cycle. Time-dependent deformation o ccurs whe n t he i ndentation d isplacement

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Characterization of the Surface Mechanical Properties of Paints and Polymeric Surface Coatings

increases wh ile t he me an s tress (me asured ha rdness) decreases. I n a t ypical fat igue t est, la rge a mplitude oscillations a re u sed t o obt ain fat igue d eformation a nd damage. Cha nges i n c ontact s tiffness w ill r epresent formation of da mage a nd c an b e mon itored u ntil fa ilure occurs. The n umber of c ycles t o fa ilure c an t hen b e determined from the elapsed time.

FIGURE 9 | Progressive load scratches made on four commercially available paint finishes: (a) acrylic latex solid deck stain; (b) low luster acrylic polyurethane; (c) porch and floor enamel; (d) latex floor and patio enamel. All scratches were made with load range 0 – 1000 mN, loading rate 0.5 N/min, speed 2000 µm/min and the indenter was a spherical diamond with radius 10 µm. Coatings were brush applied on pine board substrates and air dried for four days at ambient room temperature. Fracture thresholds (or critical failure points) are shown in dotted lines. (a)

(b)

(c)

(d)

FIGURE 10 | Complete scratch test data for two different commercially available nail varnish coatings. In each case, the data sets include the penetration depth (Pd), residual depth (R d) and frictional force (Ft), as well as the optical micrographs corresponding to the critical failure points. Load range was 0 – 3 N w ith a loading rate of 6 N/min. The varnish in (a) shows first failure at 1.94 N and complete delamination at 2.86 N, whereas the varnish in (b) shows first failure at 0.95 N and complete delamination at 1.36 N.

2.0 .6

100 00

Rd

(a)

Pd

.2 Ft

0.8 0.4 0N 0.02 N

2.0

80

16.0

1.6

60

32.0

1.2

40

48.0

0.8

20

64.0

0.4

100 0.0

(b)

0.62

1.21

1.81

2.40

0% 80.0µ 00N 3.00 0.02 N

.00 mm 1.60

3.20

4.80

6.40

8.00

34

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028 CSM FT.indd 34

Pd

80 0.2 60 0.4

Ft

40 0.6 20 0.8

0.62

1.21

1.81

2.40

0% 1.0µm 3.00

0.00 mm 1.60

3.20

4.80

6.40

8.00

Scratch Testing The most common type of scratch test consists of progressive load ing up t o a m aximum va lue. O ptical microscopy is then used to correlate a particular event (such as coating delamination) with one of t he measured signals: P enetration d epth ( Pd), R esidual dept h (R d) a nd Frictional f orce (F t). E xamples of s cratch t ests on t hree typically d ifferent, y et c ommon, p olymeric c oatings a re shown in Figure 6. Optical m icroscopy u sually p rovides s ignificant additional i nformation a s t o t he me thod of fa ilure of t he coating and an idea of the severity of the resultant plastic deformation. For example in Figure 6, material (a) fails in a d istinct a nd br ittle m anner, p roducing la rge a mounts of debris that will diffract light and make the surface look rough. Some r esults on a utomotive c oatings a re sho wn i n Figures 7 a nd 8 a nd c ome f rom a s tudy t hat c onsisted of s electing 1 0 d ifferent m aterials t hat w ere a ll h ighbake ( 140 ºC ) p olymer t opcoats. They c onsisted of a pigmented ba secoat (t hickness = 1 2 µ m), wh ich w as applied f irst, fol lowed by t he cle arcoat (t hickness = 4 5 µm) a nd s ubsequent ba king. The ba se i ngredients of each s ample c onsisted of ac rylic, me lamine, u rethane, silane a nd c arbamate. The s amples w ere eva luated a s “unweathered” a nd “weathered”, the l atter c onsisting o f 400 h i n a Xe non A rc w eatherometer u sing b orosilicate inner and outer filters. Such filters give a better equivalent spectra t o s unlight a nd 4 00 h i s ap proximately e qual t o three months in service. This is also the period of time in which customers provide the manufacturer with feedback on the quality of their vehicles. The r esults p resented i n F igure 7 sho w p rogressive load me asurements o ver t he ra nge 0 – 2 0 m N on t wo different t opcoats. The p re- a nd p ost-scan mo des of t he CSM Instruments Nano Scratch Tester were used in order to plot the penetration depths during the scratch tests and thus e valuate th e l evel o f v iscoelestic r ecovery a fter th e tests. Cle arly, s ample A sho ws a g reater r elaxation t han sample B a nd m uch le ss pla stic d eformation a long t he sides of the scratch path. The greater the deformation, the more gloss is lost from the surface of the coating. A t ypical c orrelation b etween r esidual s cratch d epth and g loss r etention i s shown i n F igure 8a whe re eight of the t ested s amples ap pear t o fo rm a l inear r elationship for tests carried out at a c onstant load of 5 m N. Note that these results are for unweathered samples. Figure 8b demonstrates that for some samples, the scratch r esistance im proves af ter w eathering. In t his example, t wo p oints a re plot ted fo r e ach s ample w ith a n arrow denoting the transition after the weathering period; in c ertain c ases ( samples E , H a nd J) t he ap plied load required fo r c oating f racture i s s ignificantly i ncreased. Such a phe nomenon c ould b e ex plained by a ha rdening of t he c oating a s a r esult of t he w eathering p rocess, o r chemical modifications due to UV exposure. In polymers such as automotive topcoats, there are three fundamental deformation mechanisms: elastic deformation, plastic d eformation a nd f racture. The re a re a lso c omplex, time-dependent rel axation p henomena ( visco-elastic a nd visco-plastic) for polymer coatings. Elastic deformation does

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Charlie Hegedus Research Associate

Q

I’m continuing to experience surface defects such as pinholes and craters in my coatings. Help.

Surfaces contaminated with dirt and dust are difficult to wet, and problems such as pinholes, fish eyes and craters often result when coatings are applied to such a surface. The key to effective, defect-free coverage is for the surface tension of the waterborne system to be lower than the surface energy of the substrate. Also, ineffective or incompatible defoamers can make matters worse. Choosing an efficient, low-foam dynamic wetting agent can help by wetting surface contaminants and significantly reducing the need for defoamers. Superwetters such as EnviroGem® 360 and Dy¯nolTM 604 surfactants provide maximum low-foam dynamic wetting for difficult systems, and Air Products’ range of Surfy¯nol® DF series defoamers provides a balance between foam control and compatibility.

A

tell me more www.airproducts.com/ surfactants © Air Products and Chemicals, Inc., 2010 (32538) B42

Characterization of th e Sur face Mechanical Properties of P aints and Polymeric Surface Coatings

FIGURE 11 | Typical test data from a pin-on-disk Tribometer test made on a commercially available paint coating deposited on a steel substrate. The static partner was a 100Cr6 steel ball applied with load 1 N and speed 20 cm/s. The coating fails after a distance of 37 m (shown as a dotted line) and the optical micrograph of the wear track confirms that the coating has been completely removed. Friction Coefficient (μ)

Ask the Expert

2.00 1.50 1.00 0.50 0.00 -0.50 -1.00

0.00 0.01 0.01 0.02 0.02 0.03 0.03 0.04 0.04 0.05 0.05 Distance (km)

not r esult i n p ermanent da mage a nd w ill not a ffect t he ap pearance of t he c oating. Plastic d eformation a nd f racture a re t he two d amage m echanisms th at w ill h ave an e ffect on t he c oating ap pearance, a nd these two mechanisms are related in a very complicated fa shion bu t u sually c ompete and c onstrain e ach ot her. Whe n f racture occurs, e lastic e nergy bu ilt up du ring t he loading process is released. The m ajority of the energy is used to produce new m aterial surfaces a s c racks p ropagate i nto t he coating. P lastic d eformation cha nges t he shape o f th e m aterial w ith o nly m inimal change in s urface ar ea. D uring p lastic deformation, e nergy i s d issipated a nd heat is g enerated. T he e nergy d issipation of pla stic d eformation i mpedes e lastic energy bu ilt up a nd p revents f racture. It is d ifficult to e valuate m ar r esistance based on a s ingle qua ntity b ecause of t he two d ifferent d eformation me chanisms involved. I n ad dition, t he t wo d eformation mechanisms result in different morphology and v isual e ffect. Ma ny c urrently u sed ‘mar’ t ests do r eport a s ingle n umber fo r mar p erformance w ith n o r egard fo r t he mechanism of da mage. Su ch t ests i gnore the dif ferent vi sual im pact t hat dif ferent scratch morphologies may produce. In t he s cratch t est, t he i ndenter c an be d riven t hrough a ll t hree r egimes of deformation, f rom e lastic t o pla stic a nd finally t o f racture. The me chanical thresholds between d ifferent deformation regimes are obviously the most important in evaluating mar resistance of materials. The t hreshold f rom pla stic d eformation to f racture i ndicates t he m agnitude of resistance a gainst f racture da mage. The fracture t hresholds a re ea sily o btained from a s cratch t est, by f inding t he f irst abrupt fluctuation where fracture occurs. The on set of f racture w ill va ry significantly d epending o n b oth t he coating a nd the substrate, wh ich is why it is a lways r ecommended t hat a c oating b e tested o n th e s ubstrate w hich is i ntended

for t he e nd-use ap plication. E xamples of differing fracture thresholds are illustrated in F igure 9, wh ich shows p rogressive load scratches o n f our c ommercially a vailable paint f inishes. A s t hese p aints a re a ll destined for application to wood substrates, the tes ts th emselves w ere pe rformed o n pine boards that had been brush coated and a ir d ried. The d ry t ime i s a lways important w hen a ssessing p olymeric materials as th ey w ill c ure a nd h arden over qu ite s ignificant t ime p eriods ( some automotive f inishes a re o nly c onsidered “hard” 6 months after deposition!). In these four exa mples, t he d ifferences b etween them a re v ery ap parent: s ample (a ) a nd (d) fa il by r epeated r upture of t he coating, whereas s ample (c) t ends t o c rack a nd sample ( b) on ly f ractures w ith v ery s mall cracks which are hardly visible at t his low magnification. I f t hese fou r s amples w ere subjected to gloss tests or consumer studies then sample (b) would probably be the best in terms of visible damage to the surface. Most of t he p olymeric c oatings s o fa r mentioned ha ve b een r elatively s oft bu t some c ommercially a vailable p olymeric finishes c an sho w qu ite br ittle p roperties. Figure 10 sho ws t wo d ifferent na il p olish coatings: sample (a) is noticeably brittle in nature a nd t he m icrographs c onfirm t hat delamination o ccurs i mmediately w ithout any transition phase where cracking might occur. I n ad dition, t he d elaminated a rea extends around the scratch, which suggests that th ere m ight be s ignificant r esidual stress in this coating-substrate system. The results g raph fo r s ample (a ) sho ws t hat some v iscoelastic r ecovery ha s o ccurred after s cratching ( seen a s t he d ifference between the Pd and Rd signals). For sample (b) the optical m icrographs show that this varnish ha s a v ery d ifferent d eformation mode, cha racterized by s ignificant pla stic deformation along the edges of the scratch. It can also be observed that sample (b) fails at a much lower load (and at a much lower penetration depth) than sample (a).

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All t hese exa mples d emonstrate t he power of t he s cratch t est fo r me asuring relevant m echanical q uantities d uring formation of da mage, a s well a s t he h igh accuracy a nd r eproducibility o f th is quantitative method.

Wear Testing The adva ntage of a w ear t est, whe n compared to indentation or scratch testing, is that it c an give a me asure of t he lifetime of a p articular p olymer c oating-substrate system. I n many c oating applications, t he resistance to wear can be more important than th e l oad r equired to pe rmanently damage the material. A t ypical set of dat a is sho wn i n F igure 1 1, fo r a p in-on-disk test made on a p aint sample. The g raph of friction coe fficient v ersus d istance s hows a steady value of f riction until the coating fails (i.e., is completely worn away). The onset of failure corresponds, in this case, to a distinct change in the friction signal, due to breakdown of the coating and formation of a tri bological tr ansfer f ilm, w hich i s a m ixture of t he c oating, s ubstrate a nd

static p artner m aterials m ixed t ogether. The coating properties being tested and the substrate on wh ich it ha s b een d eposited will influence the friction signal when the coating is w orn th rough: i n s ome c ases this signal will rise dramatically, in others it m ay d rop. Wh ichever t he cha nge, t he coating br eakdown w ill ne arly a lways manifest itself as a sharp change from the steady sliding state. In t he exa mple sho wn i n F igure 1 1, the c oating ha s fa iled a fter a sl iding distance of 3 7 m a nd s ubsequent op tical microscopy of t he w ear t rack sho ws t hat the c oating ha s b een a lmost c ompletely removed. A p rofile across t his wear t rack would e nable t he w orn s ectional a rea to be c alculated a nd th us th e w ear r ate of t his c oating m aterial. The choic e of applied load a nd g eometry of t he s tatic partner w ill determine t he l ifetime of t he coating. I f one w ants t o s imulate ha rsh conditions then a higher load and smaller static partner radius may be used in order to increase the contact pressure and make the coating fail sooner. On the other hand,

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028 CSM FT.indd 37

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Characterization of the Surface Mechanical Properties of Paints and Polymeric Surface Coatings

FIGURE 12 | Pin-on-disk Tribometer data for three commercially available nail var-

Friction Coefficient (µ)

7.50 6.00 4.50 3.00 1.50 0.00 -1.50 -3.00 -4.50 -6.00 -7.50

Friction Coefficient (µ)

7.50 6.00 4.50 3.00 1.50 0.00 -1.50 -3.00 -4.50

Friction Coefficient (µ)

nishes. All three have been subjected to the same test conditions (1 N applied load, 10 cm/s speed, distance 100 m) so that their resistance to wear can be compared. The sample in (c) has completely delaminated, whereas (a) and (c) have only partially delaminated.

Conclusions

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Distance (km)

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Distance (km)

7.50 6.00 4.50 3.00 1.50 0.00 -1.50 -3.00 -4.50

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Distance (km)

one m ight w ant t o eva luate t he ev olution of t he f riction coefficient o ver a lon g p eriod of t ime w ithout da maging the c oating, i n wh ich c ase a lo wer load a nd/or la rger contact geometry might be chosen. In a ddition t o e valuating th e fri ctional an d w ear properties of t he c oating, it i s s ometimes i nteresting t o evaluate the said properties as a function of atmosphere, temperature an d in d ry/liquid e nvironments. C SM Instruments Tribometers are equipped to handle samples that a re c ompletely s ubmerged i n a p articular l iquid and ha ve t he c apability t o p erform t ests up t o 1000 ºC. Atmospheres c an a lso b e pu mped i nto t he m achine i f required, e.g., A rgon, N 2, e tc. H igh-vacuum T ribometers are a lso available for eva luating c oatings, wh ich m ay b e used i n s pace o r vac uum c onditions a nd a re c apable of vacuums down to 10 -7 Torr. A s election of w ear t est r esults on t hree d ifferent nail c oating s amples a re sho wn i n F igure 1 2. A ll t hree samples w ere p repared w ith th e s ame th ickness, w ere deposited on t he s ame s ubstrate a nd w ere t ested w ith identical me asurement p arameters i n o rder t o b e able t o directly c ompare t heir r esistance t o w ear. The c riterion in t his s et of t ests w as t o i nvestigate t he r esistance of the c oating a fter a sl iding d istance of 1 00 m w ith 1 N applied load and a speed of 10 cm/s. For a wear track with a d iameter of 1 0 m m, t his t otal d istance c orresponds t o 1592 rotations (or laps) of the sample and the test duration was approximately 17 minutes. In this example, the friction traces do not show a distinct point where the coating has broken down, but the subsequent op tical m icroscopy i mages sho w cle arly ho w 38

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much of t his r ed c olored c oating r emains i n e ach c ase. Sample (a ) ha s on ly sl ightly d elaminated at t he e nd of the test, whereas sample (c) ha s completely delaminated. Sample (b) shows almost complete delamination and some quite j agged e dges a long t he w ear t rack wh ich s uggest that this particular varnish is rather brittle in nature. This p aper ha s p resented t he lat est s tate-of-the-art instrumentation me thods a vailable fo r cha racterizing the me chanical p roperties of p olymeric c oating materials. S everal exa mples of t ests p erformed on common co mmercially a vailable co atings h ave be en presented i n o rder t o h ighlight t he ap plicability of e ach type of t est. I n mo st e nd-use ap plications of c oatings, the ap pearance r emains one of t he m ain c riteria a nd it has b een sho wn t hat t he me chanical p roperties of s uch materials c an b e d irectly c orrelated t o t heir ae sthetic quality. By u nderstanding ho w t he m aterial d eforms, the r esearcher c an d evelop a c oating t hat w ill b e mo st suited to the in-service conditions that it will encounter. Understanding t he ad hesive p roperties of t he c oatingsubstrate combination will allow a better choice of coating for a particular substrate type. 䡲 For more information, contact Dr Nicholas X. Randall at Tel: 781/444.2250; Fax: 7 81/444.2251; e -mail nra@c sm-instruments.com or v isitwww.csminstruments.com.

References

Briscoe, B.J. Isolated contact stress deformations of polymers: the b asis fo r i nterpreting p olymer t ribology. Tribology International 1998, 31, 121-126. 2 Briscoe, B. J.; P elillo, E .; Si nha, S. K. S cratch h ardness a nd deformation m aps fo r p olycarbonate a nd p olyethylene. Polymer Engineering and Science 1996, 36 (24), 2996-3005. 3 Consiglio, R.; Randall, N.X.; Bellaton, B.; von Stebut, J. The Nano S cratch T ester ( NST) a s a new t ool fo r a ssessing t he strength of u ltrathin hard coatings a nd the mar resistance of polymer films. Thin Solid Films 1998, 332, 151-156. 4 Courter, J.L.; Kamenetzky, E.A. Micro- and nano-indentation and s cratching fo r e valuating t he m ar r esistance of automotive c learcoats. European C oatings Jo urnal 1999, 7, 24-38. 5 Lin, L .; Bl ackman, G .; M atheson, R . M icro-mechanical characterization of ma r b ehavior of a utomotive t opcoats: micro- and nano- wear of p olymeric materials.ACS Polymer Preprints 1998, 39, 1224-1225. 6 Lin, L .; Bl ackman, G .; M atheson, R . Q uantitative characterization of s cratch a nd m ar b ehavior of p olymer coatings. Materials Science & En gineering 2001, A317, 163170. 7 Gregorovich, B. ; Ad amsons, K .; L in, L . S cratch a nd m ar and ot her m echanical p roperties a s a f unction of che mical structure f or a utomotive ref inish co atings. Progress in Organic Coatings 2001, 43, 175-187. 8 Pangarajan, P.; Sinha, M.; Watkins, V.; Harding, K.; Sparks, J. Scratch visibility of polymers measured using optical imaging. Materials Engineering and Science 2003, 43 (3), 749-758. 9 Lin, L .; Bl ackman, G .; M atheson, R . A new ap proach t o characterize s cratch a nd m ar r esistance of a utomotive coatings. Progress in Organic Coatings 2000. 40, 85-91. 10 Courter, J.L. Mar resistance of automotive clearcoats: relationship t o c oating me chanical p roperties. J ournal of Coating Tech. 1997, 69, 57-63. 1

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Alkylphenol Ethoxylate-Free Sulfates in

Emulsion Polymerization

I

n eem emulsion emul mullsi sion ppolymerization, olym ol ymer eriz ization, aalkyl lkyl eether ther ssulfates ulfates are one of t he m ajor s urfactants ne cessary t o provide fo r t he s tabilization of m icelles. T raditionally, t hese s ulfates ha ve b een ba sed on alkylphenol e thoxylates ( APEOs). The ir g ood cost/performance c oupled w ith t heir d istinctive s tructural a nd physical p roperties ha s le d t o t heir w idespread use i n e mulsion po lymerization. H owever, a lternative surfactants a re d esired t o ex pand t he fo rmulators’ s urfactant options and give materials that are free of A PEOs. Previous wo rks s howed t hat n arrow-range a lcohol e thoxylates, ba sed on d ifferent h ydrophobic fe edstocks, a re effective A PEO a lternatives a s n onionics i n e mulsion polymerization. By ex ploiting t he n onionic w ork, new APEO-free e ther s ulfates ha ve b een d eveloped t hat y ield emulsion p olymerization cha racteristics s imilar t o t hat of t he A PEO-based e ther s ulfates. Th us, t he fol lowing work co mpares a nd co ntrasts sta ndard i ndustrial A PEO anionic emulsifiers with new non-APEO-based alternative anionic surfactants in model systems.

Introduction With t he r eduction i n t he m arketplace of m any s olventbased p olymerizations, e mulsion p olymerization ha s become o ne o f th e p reeminent m ethods. T his tec hnique

FIGURE 1 | Representative chemical structures of APEO ether sulfates. O

O

H x

O

Nonylphenol Ethoxylate (NPE) O

O S O O xO

Nonylphenol Ether Sulfate (NPES)

O

H x

Octylphenol Ethoxylate (OPE) Z

O

O S O O O x

Octylphenol Ether Sulfate (OPES)

Z

relies on the formation and long-term stability of micelles. Typically, e mulsion f ormulation u tilizes tw o types of s urfactants: on e n onionic a nd t he ot her a nionic.1 Each p rovides s eparate s tabilization me chanisms for t he m icelles, bu t t he c ombination p rovides b etter stabilization, e specially a s t emperature i ncreases. T he nonionic s urfactants b estow a s teric s eparation b etween micelle groups, while anionic surfactants yield a cha rged repulsion between the micelles. For m ost i ndustries t hat pr actice em ulsion polymerization, including coatings, the main hydrophobe used for both the nonionic and anionic surfactants for the past 45 years has been alkyl phenol (either octylphenol or nonylphenol).2 In general, a standard emulsion formula would employ an alkyphenol ethoxylate (APEO) with a high number of moles of ethylene oxide (usually >20) as the nonionic, and an APEO with 3 t o 7 mole s of e thylene oxide, which was then sulfated as the anionic surfactant. Utilized i n c onjunction, t hese of fered t he b est fo rmation and s tabilization of t he m icelle du ring a nd fol lowing the e mulsion p olymerization. Ad ditionally, t hese A PEO surfactants p rovided t he op timum c ost/performance properties d esired by fo rmulators fo r m any y ears. A n example structure of each APEO is given in Figure 1. Alkylphenol e thoxylates a nd e ther s ulfates i n g eneral possess a n umber of s tructural, c ompositional a nd performance attributes that have helped them to reach high consumption rat es fo r e mulsion p olymerization i n N orth America. A number of these advantages are listed in Table 1. In 2 006, t he t otal s urfactant u sage fo r e mulsion polymerization wa s 1 06,400 met ric t ons (c alculated a s 100% active), which is a modest 3% growth over volumes used in 2004. This has slowed dramatically over the recent economic downtown; however, t he outlook for g rowth for emulsion polymerization is still positive over the next five years. O f t he 2 006 v olume, n onionic s urfactants m ade up 55,000 metric tons or >50% of the total surfactant volume, wh ile a nionics t ook up mo st of t he r emainder with 51,400 metric tons.3 Sales of APEO-based surfactants accounted for most of the total nonionic surfactant volume, including 2 2,700 me tric t ons o ctylphenol ( OPEs) a nd 17,700 me tric t ons n onylphenol (N PEs) e thoxylates a s nonionics. Ad ditionally, t he A PEO s urfactants ac counted

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for another 8,200 metric tons as anionics, of wh ich much was n onylphenol e ther s ulfate (a ll n umbers c alculated at 1 00%).3 The se p articular n onionics a nd a nionics were p referred fo r e mulsion p olymerization b ecause t hey provided cost ef fectiveness a nd i mproved pa rticle st ability over a w ide ra nge of t hermal, me chanical a nd e lectrolyte conditions v ia s teric s tabilization fo r t he n onionics a nd charge stabilization for the anionics.1,4

Recent Trends for Substitution of APEOs Despite a ll of t he a forementioned adva ntages fo r A PEOs and t he s ulfate a nalogs, t heir u se i n N orth A merica ha s started to decline. The trend, which has been dramatic over the past two years for household detergent applications, is now moving to many industrial applications in North America. Some of this is due to governmental pressure. Like the EU (European Union), which has already banned the use of APEOs for applications where these surfactants could c ontact s ewer w ater, t he C anadian g overnment is starting to regulate APEO use. In fact, Canadian legislation i s r equiring a 9 0% r eplacement of a ll A PEOs including t heir d erivatives lik e s ulfates wi thin p roducts consumed in Canada by 2010.5,6 In contrast, the pressure in the United States is not coming so much from the federal government a s f rom la rge merchandisers s uch a s Wal-Mart a nd H ome D epot. They a re e ncouraging t heir suppliers of all consumer products (household detergents, paint, e tc.) t o u se e co-friendly c omponents w ithin t heir product fo rmulations. A s a r esult, u se of N PEs a nd N PE sulfates, in p articular, ar e b eing p hased o ut.7,8 T able 2 shows s ome of t he d isadvantages of A PEOs, wh ich a re driving their reduced use in industrial applications. In addition to the disadvantages, the cost/performance advantage t hat A PEOs a nd t he d erivatives ha ve historically e njoyed ha s c ome u nder p ressure due t o higher p etroleum p rices a nd l imited a vailability of t he feedstock propylene trimer, which is used to manufacture the nonylphenol hydrophobe.9,10

Previous APEO Alternatives In p rior w ork on e mulsion p olymerization, n onionic surfactant alternatives to APEOs were examined. The results of t his r esearch s uggested new er h ydrophobes, including i sotridecyl a lcohol (T DA) ba sed on n- butene feedstock a nd Fisc her-Tropsch ( “FT”) p rocess-based alcohols (FT-OXO) with carbon range of 12 to 13 (Figure 2 ), w ere a b etter m atch fo r t he p roperties of octylphenol a nd n onylphenol t han ot her a lternatives in t he m arketplace whe n c oupled w ith na rrow-range ethoxylation. N onionic s urfactants d erived f rom t hese hydrophobes a nd na rrow-range e thoxylation r esulted i n equal o r b etter p erformance t han N PE o r t he s tandard OPE in a standard emulsion polymerization.

Applying Previous Knowledge The p revious w ork, a gain, c entered on t he n onionic portion of t he s urfactant p ackage fo r e mulsion polymerization.11 Th us, by u tilizing t he k nowledge f rom this p revious r esearch on new h ydrophobes a nd t he narrow-range e thoxylation t echnology, ani onic an alogs should b e p ossible. C urrently, t he i ndustrial s tandard

anionic s urfactant fo r e mulsion p olymerization i s a n NPE 3-mole ethoxylate sulfate. This APEO ether sulfate is very versatile and resilient to a wide variety of processing conditions in multiple types of e mulsion polymerizations. One r eason fo r t he a nionic s urfactant’s s uccess i s t he lack of free nonylphenol sulfate. Therefore, to best match these cha racteristics ba sed on t he previous k nowledge, a narrow-range (NR) T DA or F T-OXO e ther s ulfate ( Figure 3) should manage to satisfy these requirements.

FIGURE 2 | Example chemical structures of APEO alternatives.

O

H O

FT-OXO Alcohol Ethoxylate

x

O

H O x

Isotridecyl Alcohol Ethoxylate

FIGURE 3 | Example chemical structures of APEO alternative ether sulfates. O S

O O

Z

O

x FT-Oxo Ether Sulfate O S

O O

O

Z

O x

Isotridecyl Ether Sulfate

TABLE 1 | Compositional and performance advantages for alkylphenol ethoxylates and sulfates (APEOs). 1. 2. 3. 4.

Excellent emulsification properties. Good versatility – useful in a variety of emulsion polymerization types. Branched structure yields lower solidification points and less gelling. Low levels of free un-ethoxylated phenol; low VOC.

5. Narrower range EO adduct distribution compared to base-catalyzed primary alcohol ethoxylates. 6. Historically APEOs have maintained a lower cost compared to other alcohol ethoxylates (AEs).

TABLE 2 | Disadvantages for alkylphenol ethoxylates. 1. Biodegradation of APEOs is slower than that of other AEs. 2. Biodegradation occurs along the EO chain for APEO. As degradation proceeds, the resulting metabolites are more surface active and more toxic than the starting intact APEO structure. 3. Growing attention on environmental properties of APEOs.

PA I N T & C O A T I N G S I N D U S T R Y

040 Sasol FT.indd 41

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Alkylphenol Ethoxylate-Free Sulfates in Emulsion Polymerization

In o rder t o b etter d emonstrate t he p erformance of the s ulfates d iscussed ab ove a s a nionic A PEO-free surfactants, a study was undertaken to employ a standard emulsion p olymerization. The fol lowing s ections d iscuss the s urfactants eva luated, t he p olymerization a nd t he analysis methods employed.

Sulfation In o rder t o exa mine t he e ffect of A PEO a nionic s urfactant alternatives on e mulsion p olymerization, t he mo del monomers need to be synthesized. With APEOs, the sulfation is a ccomplished b y r eacting th e n onylphenol e thoxylate with s ulfamic ac id, wh ich i s a m ild s ulfation a gent.12 Th is sulfation r eaction i s done i n a bat ch p rocess. The s ulfamic

FIGURE 4 | Example of sulfation of NPE. O

NH2SO3H O R OH

-

+

O R O S O NH4 O

FIGURE 5 | Example of sulfation of APEO with sulfur trioxide (acid form). R1

SO3

O R2 OH

O R1

O S

O R2

O

+ R1

OH

O

O R2

HO3S

O S OH O

FIGURE 6 | Example of sulfation of APEO alternative with sulfur trioxide and neutralization.

R

OH

SO3

O R

O

S O

OH

NaOH

O R

O

S

_ O Na++ H 2O

O

TABLE 3 | Latex formula. Ingredient

Grams

Kettle Charge De-ionized water 102.51 Potassium persulfate 1.80 Pre-Emulsion (4 h feed) De-ionized water 142.32 Surfactant 3. 00* n-Butyl acrylate 291.00 Acrylic acid 3.00 2-Hydroxyethyl acrylate 6.00 Potassium persulfate 0.75 Post Add De-ionized water 3.00 ANATROX BL225** 0.15 Total 553 .53 * c alculated f or N PE-3 su lfate “ as is ” ( ~26.12% a ctive) a nd o ther su rfactants adjusted for solids ** from Rhodia 42

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acid preferentially reacts with a terminal hydroxyl group to form an ammonium sulfate salt (Figure 4). Unfortunately, t here a re s ome d rawbacks t o s ulfation with s ulfamic ac id. U sing t his bat ch p rocess a nd a mo re costly sulfation agent increases the costs for the production for A PEO-based e ther s ulfates. F urthermore, on ly t he ammonium s alt is p roduced b y th is tec hnique, a nd th e ammonium salt can be less stable due the volatilization of ammonia over time. A le ss ex pensive s ulfation p rocess i s c alled t hin f ilm sulfation using air/SO3. In this case, the sulfation agent is sulfur trioxide produced directly on demand. Pure sulfur is burned in very dry air to make sulfur dioxide, which is th en o xidized o ver a V 2O5 catalyst to form SO3. Th is process i s c ontinuous, e fficient, e conomical a nd w idely practiced in the surfactant industry,13 but, unfortunately, it c annot b e u sed fo r t he s ulfation of A PEOs. That ’s because the sulfur trioxide, a very strong sulfation agent, will sulfonate the phenol ring as well as sulfate the intended hydroxyl group (Figure 5).14 This le ads t o p oorer s urfactant p roperties, r esulting in u nstable e mulsions; ho wever, t he a lcohol e thoxylate alternatives to APEO do not have the phenol ring. For the surfactant i ndustry, t hese a re s ulfated u sing t he mo re efficient a nd le ss ex pensive t hin f ilm a ir/SO3 su lfation process ( Figure 6 ). Wit h t his s ulfation t echnique t he alcohol e thoxylate s ulfuric ac id e ster c an b e neu tralized with a ny d esired ba se, i n c ontrast t o t he s ulfamic ac id technique, which yields only the ammonium salt. 12-14

Experimental For this study, an ammonium salt of nonylphenol ether sulfate w ith 4 mole s of e thylene o xide w as e mployed a s the s tandard A PEO e ther s ulfate fo r t he a nionic i n t he forthcoming emulsion polymerization. This material was obtained f rom a n ex isting s upply. F or t he A PEO-free alternative ether sulfate, two isotridecyl-based ethoxylates were chosen. One was based on the standard base catalysis to fo rm t he br oad ra nge e thoxylate ( BRE), a nd t he ot her used th e n arrow-range tec hnology ( NRE).15,16 The se proceeded to sulfation.

Sulfation For the APEO alternatives, a lab oratory thin film sulfation unit sulfated the ethoxylates at a SO3/ethoxylate mole ratio of 1.01. The r esulting acids were neutralized i n a s eparate reactor i n a c ontinuous fa shion w ith s odium h ydroxide to fo rm a ~ 25% ac tive s olution. The N PE e ther s ulfate standard was obtained from a vendor and used “as is.”

Latex Production This s tudy e mployed s emi-continuous e mulsion polymerization t o p roduce a ll-acrylic lat exes. T able 3 outlines the formulation utilized for this examination. The theoretical solids are 55.01% and 54.72% after the post add.

Polymerization The p olymerization r eaction ke ttle w as f illed w ith t he prescribed amount of water, purged with nitrogen and heated to 80 °C using a w ater bath. The n itrogen blanket was m aintained t hroughout t he e ntire p olymerization.

SEPTEMBER 2010 | W W W . P C I M A G . C O M

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Alkylphenol Ethoxylate-Free Sulfates in Emulsion Polymerization

The mon omer m ixture a nd aque ous m ixture w ere prepared s eparately. E ach of t he c omponents fo r t he respective m ixtures w ere a dded s lowly to gether a nd blended t horoughly. The i nitiator s olution w as p repared by dissolving potassium persulfate in water. The monomer a nd aque ous m ixtures w ere fe d s eparately but s imultaneously i nto t he r eaction v essel o ver a 4 h period wh ile t he i nitiator s olution w as ad ded o ver a 4 h a nd 1 0 m in p eriod. The p olymerization t emperature was m aintained a t 8 0 ° C t hroughout t he a ddition tim e and for a n additional 2 h t o ensure complete conversion. The r eaction ke ttle w as c ooled t o a mbient t emperature over a 2 h p eriod. Nex t, t he p ost ad d, wh ich i s a l inear 8-10 a lkoxylate f rom R hodia (r eferred t o a s A NTATROX BL225), a nd w ater w ere plac ed i nto t he e mulsion t o increase the stability of the final latex formulation. Finally, the pH w as adjusted to 8 u sing a mmonium hydroxide to ensure stability of the anionic surfactant. The t otal s urfactant p ackage fo r t he e mulsion polymerization included only anionic surfactant, and in this formulation no nonionic s urfactants were exa mined. Th is allowed for the only stability effects for the polymerization to be due to the anionic surfactant being examined.

TABLE 4 | Properties of the ether sulfates. Anionic Surfactant Nonyl phenol ethoxylate sulfate* NRE Isotridecyl alcohol based on n-butene ethoxylate sulfate BRE Isotridecyl alcohol based on n-butene ethoxylate sulfate

Active (wt %)

Free Oil (wt %)

Salt (wt %)

26.80

0.30

2.40**

23.64

1.19

0.09***

22.11

0.98

0.16***

* sulfated by sulfamic acid ** salt in the form of ammonium sulfate *** salt in the form of sodium sulfate

TABLE 5 | Anionic surfactant and resultant latex properties. Anionic Surfactant Nonyl phenol ethoxylate sulfate NRE Isotridecyl alcohol based on n-butene ethoxylate sulfate BRE Isotridecyl alcohol-based on n-butene ethoxylate sulfate

pH

Solids Wet Coagulum Conversion (%) (%) (%)

Particle Size (nm)

8.20

54.5

>0.2

99.0

144

8.04

53.7

>0.2

97.6

143

8.02

53.7

>0.2

97.6

154

TABLE 6 | APEO-free ethoxylates prior to sulfation. Moles of EO

Free Alcohol (%)

Polyethylene Glycol (%)

Melting Point (°C)

NRE Isotridecyl alcohol based on n-butene ethoxylate

3

20

0.16