handbook of detergents analysis

Although great care has been taken to provide accurate and current information, neither the author(s) nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage, or liability directly or indirectly caused or alleged to be caused by this book. The material contained herein is not intended to provide specific advice or recommendations for any specific situation. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress. ISBN: 0-8247-0351-0 This book is printed on acid-free paper. Headquarters Marcel Dekker 270 Madison Avenue, New York, NY 10016, U.S.A. tel: 212-696-9000; fax: 212-685-4540 Distribution and Customer Service Marcel Dekker Cimarron Road, Monticello, New York 12701, U.S.A. tel: 800-228-1160; fax: 845-796-1772 World Wide Web http://www.dekker.com The publisher offers discounts on this book when ordered in bulk quantities. For more information, write to Special Sales/Professional Marketing at the headquarters address above. Copyright n 2005 by Marcel Dekker. All Rights Reserved. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher. Current printing (last digit): 10 9 8 7 6 5 4 3 2 1 PRINTED IN THE UNITED STATES OF AMERICA

Handbook Introduction

The battle cry for sustainable development is persistent in all circles, gaining acceptance, worldwide, as the guiding rationale for activities or processes in the science–technology–environment–economy–society interfaces targeting improvement and growth. Such activities are expected to result in higher standards of living, leading eventually to a better quality of life for our increasingly technology-dependent modern society. Models of sustainable management are continually being developed and/or adapted and creatively applied, taking into consideration human needs versus wants on the one hand, and long- versus short-term benefits and tradeoffs on the other. ‘‘Detergents’’ constitute a classic case study within this context: this is a multidimensional systemic enterprise, operating within complex sociopolitical/technoeconomical realities, locally and globally, reflecting in its development and contemporary ‘‘state-of-affairs’’ the changing dynamic equilibria and interrelationships between demands/needs, cost/benefits, gains/tradeoffs, and social preferences. Interestingly, it is not surprising, despite the overall maturity of the consumer market, that detergents continue to advance more rapidly than population growth. The soap and detergent industry has seen great change in recent years, responding to the shifts in consume preferences, environmental pressures, the availability and cost of raw materials and energy, demographic and social trends, and the overall economic and political situation worldwide. Currently, detergent product design is examined against the unifying focus of delivering to the consumer performance and value, given the constraints of the economy, technological advancement, and environmental imperatives. The annual 2–3% growth of the detergent industry and a higher growth in personal care products reflect impressive developments in formulation and application. The detergent industry is thus expected to continue steady growth in the near future. For the detergent industry, the last decade of the twentieth century has been one of transformation, evolution, and even some surprises (e.g., the increase of heavy-duty liquid detergents at the expense of powder detergent products). On both the supplier and consumer market sides (both remain intensely competitive), the detergent industry has undergone dramatic changes, with players expanding their offerings, restructuring divisions, or abandoning the markets altogether. This has resulted in the consolidation iii

iv

Handbook Introduction

of the market, especially in the last several years, and this trend appears to be gaining momentum. The key concepts have been and still are innovation, consume preferences, needs, multipurpose products, cost/benefit, efficiency, emerging markets, partnership–cooperation–collaboration–merging (locally, regionally, and globally), and technological advancements. Although substantial gains and meaningful rapid changes with respect to the preceding concepts have been experienced by the surfactants/detergents markets, the same cannot be said for detergents/surfactant technology itself. The $9-billion-plus detergent ingredients market has many entrenched workhorse products. This may suggest that the supply of ‘‘solutions’’ to most cleaning ‘‘problems’’ confronted by consumers in view of the increasing global demand for a full range of synergistic, multifunctional detergent formulations having high performance and relatively low cost, and the need for compliance with environmentally oriented (green) regulation, may be based on modifications of existing technologies. What does all this mean for the future of the detergent enterprise? How will advances in research and development affect future development in detergent production, formulation, applications, marketing, consumption, and relevant human behaviors as well as short- and long-term impacts on the quality of life and the environment? Since new findings and emerging technologies are generating new issues and questions, not everything that can be done should be done; that is, there should be more response to real needs rather than wants. Are all the questions discussed above reflected in the available professional literature for those who are directly involved or interested engineers, scientists, technicians, developers, producers, formulators, managers, marketing people, regulators, and policy makers? After a thorough examination of the literature in this and/or related areas, I came to the conclusion that a comprehensive series was needed that focuses on the practical aspects of the topic and provides the detergent industry perspective to all those involved and interested. The Handbook of Detergents is an up-to-date compilation of works written by experts each of whom is heavily engaged in his or her area of expertise, emphasizing the practical and guided by a common systemic approach. The aim of this six-volume handbook (Properties, Environmental Impact, Analysis, Formulation, Applications, and Production) is to reflect the above and to provide readers who are interested in any aspect of detergents a state-of-the-art comprehensive treatise, written by expert practitioners (mainly from industry) in the field. Thus, various aspects involved—raw materials, production, economics, properties, formulations, analysis and test methods, applications, marketing, environmental considerations, and related research problems—are dealt with, emphasizing the practical in a shift from the traditional or mostly theoretical focus of most of the related literature currently available. The philosophy and rationale of the Handbook of Detergents series are reflected in its title, its plan, and the order of volumes and flow of the chapters (within each volume). The various chapters are not intended to be and should not necessarily be considered mutually exclusive or conclusive. Some overlapping facilities the presentation of the same issue or topic from different perspective, emphasizing different points of view, thus enriching and complementing various perspective and value judgements. There are many whose help, capability, and dedication made this project possible. The volume editors, contributors, and reviewers are in the front line in this

Handbook Introduction

v

project. Many others deserve special thanks, including Mr. Russell Dekker and Mr. Joseph Stubenrauch, of Marcel Dekker, Inc., as well as my colleagues and friends in (or associated with) the detergent industry whose dedication and involvement certainly facilitated this work. My hope is that the final result will complement the tremendous effort invested by all those who contributed; you the reader, will be the ultimate judge. Uri Zoller Editor-in-Chief

Preface

The intention of this volume is to demonstrate the state of the art of strategies, methods, and techniques applied for the analytical deformulation of modern detergents. These are defined as surface active agent containing formulations, used in household and industry in aqueous application solutions for the cleaning of textiles and hard surfaces. The emphasis is on up-to-date techniques and methods that are proved effective and useful in daily work. In order to impart to the reader, besides product analysis, a comprehensive view of all aspects of detergents, typical ingredients of modern products, testing of application abilities detergent formulations, and the determination of detergent ingredients in environment, are outlined in separate chapters. Furthermore, the basics of modern instrumental techniques with emphasis to application in the detergent analysis field are also described. The scope and spectrum of methods and techniques applied in detergent analysis have changed significantly during the last decade. Driving forces were the rapid progress in instrumental analysis which led to a far reaching replacement of classical labor-intensive manual procedures by modern, often computer aided instrumental techniques, and also changes in the product spectrum. The former all purpose cleansers and detergents have largely been replaced by specialized products which contain new—even in very low concentrations—effective ingredients; these require for determination more sensitive and specific methods. The field of detergent analysis can roughly be divided into two sectors: 1) quality control and 2) monitoring of the multi-billion dollar market. It is of vital interest for the market participants to know exactly what is going on there. Quality control analysis is characterized by the application of fixed, often standardized procedures and methods, which are designed in such a way, as to allow an operation with relatively simple equipment, by semi-skilled technicians. Additionally big corporations use on-line or semi on-line systems for the fully automated determination of essential parameters, not normally described in literature because they are proprietary production facilities and are therefore subject to secrecy. The analysis of unknown products from market sources, which is the main subject of this book, is due to the diversity and complexity of modern detergents, a very demanding task. It requires much experience and product knowledge, but also the vii

viii

Preface

availability of nearly the whole spectrum of the modern analysis techniques used, and, especially important, highly skilled staff. Often no defined strategy can be given; the performing analyst has to decide with respect to the product type and the individual analytical task, how to approach and how detailed the characterization of the various ingredients must be done in order to obtain the required information. Sometimes rough data about the concentration of the main raw material types are sufficient without any further determination of their exact structure. But for a comprehensive analysis often the concentrations as well as the isomer and homologue distribution of ingredients has to be determined in great detail in order to allow an identification of the contained commercial raw material. For new, so far unknown formulations or totally new raw materials, a final formula reconstruction at an acceptable price often is only possible in close cooperation of analysts, product developers, patent specialists, and marketing people. In the scope of this volume it is not possible to describe the discussed analysis methods in great detail, but the basic features and experimental parameters for many essential procedures are outlined to a degree, such that an experienced analyst may be able to use them for exploratory work. Nevertheless for a better understanding and/or use in daily routine the analyst should refer to the cited references. Heinrich Waldhoff Ru¨diger Spilker

Contents

Handbook Introduction Preface Contributors

iii vii xi

1.

Types and Typical Ingredients of Detergents Hermann G. Hauthal

1

2.

Analysis of Detergent Formulations—General Procedure Heinrich Waldhoff

101

3.

Determination of Nonionic Surfactants Kosuke Tanaka and Akinori Igarashi

149

4.

Determination of Anionic Surfactants Ru¨diger Spilker

215

5.

Analysis of Cationic and Amphoteric Surfactants Norbert Buschmann

289

6.

Analysis of Inorganic Detergent Builders Harald P. Bauer

389

7.

Sequestrants and Chelating Agents Ru¨diger Spilker and Peter Haas

425

8.

Analysis of Bleaching Agents and Bleaching Accelerators Martina Hirschen

439

9.

Analysis of Detergent Enzymes Karl-Heinz Maurer and Matthias Gabler

471

10.

Determination of Optical Brighteners in Laundry Detergents Gerd W. Heinemann and Gerhard Merkle

487

11.

Miscellaneous Ingredients Heinrich Waldhoff and Peter Haas

507 ix

x

Contents

12.

Testing Performance of Detergents and Cleansers Anke Ophu¨ls, Thomas Hilgers, and Ju¨rgen Bohnen

541

13.

Environmentally Related Analysis Bjo¨rn Thiele, Klaus Gu¨nther, and Milan Schwuger

551

14.

Analytical Techniques: Basics and Fields of Application Bernhard Menzebach

581

Future Trends Index

643 645

Contributors

Pigments and Additives (R&D), Clariant GmbH, Hu¨rth, Germany

Harald P. Bauer Ju¨rgen Bohnen

Wfk Institut fu¨r Angewandte Forschung GmbH, Krefeld, Germany University of Mu¨nster, Mu¨nster, Germany

Norbert Buschmann

Matthias Gabler y Corporate Research/Enzyme Technology, Henkel KGaA, Du¨sseldorf, Germany Klaus Gu¨nther * Institut fu¨r Angewandte Physikalische Chemie, Forschungszentrum Ju¨lich GmbH, Ju¨lich, Germany Peter Haas

BASF AG, Ludwigshafen, Germany

Hermann G. Hauthal

Consultant, Leuna, Germany

Gerd W. Heinemann Research and Development Home & Personal Care, Ciba Spezialita¨tenchemie Grenzach GmbH, Grenzach-Wyhlen, Germany Thomas Hilgers Germany

Wfk Institut fu¨r Angewandte Forschung GmbH, Krefeld,

Martina Hirschen Germany

Division of Functional Chemicals, Clariant GmbH, Frankfurt,

Akinori Igarashi Analytical Research Center, LION Corporation, Tokyo, Japan

* Current affiliation: Universita¨t Duisburg-Essen, Standort Duisburg, Germany. y Deceased.

xi

xii

Contributors

Karl-Heinz Maurer Corporate Research/Enzyme Technology, Henkel KGaA, Du¨sseldorf, Germany Bernhard Menzebach Degussa, Marl, Germany Gerhard Merkle Research and Development Home & Personal Care, Ciba Spezialita¨tenchemie Grenzach GmbH, Grenzach-Wyhlen, Germany Anke Ophu¨ls

Wfk Institut fu¨r Angewandte Forschung GmbH, Krefeld, Germany

Milan Schwuger Institut fu¨r Angewandte Physikalische Chemie, Forschungszentrum Ju¨lich GmbH, Ju¨lich, Germany Ru¨diger Spilker

Sasol Germany GmbH, Marl, Germany

Kosuke Tanaka

Analytical Research Center, LION Corporation, Tokyo, Japan

Bjo¨rn Thiele Institut fu¨r Angewandte Physikalische Chemie, Forschungszentrum Ju¨lich GmbH, Ju¨lich, Germany Heinrich Waldhoff *

* Retired.

Henkel KGaA, Du¨sseldorf, Germany

1 Types and Typical Ingredients of Detergents HERMANN G. HAUTHAL Consultant, Leuna, Germany

I. TYPES OF DETERGENTS The world of detergents comprises laundry detergents both for household, and institutional and industrial (I&I) use, a broad spectrum of cleaners for household, I&I and metal industry application, industrial detergents as functional processing aids, and cosmetic cleaners.

A. Household Laundry Detergents Household laundry products can be classified into heavy-duty detergents, specialty detergents, and laundry aids. Heavy-duty detergents are suitable for all types of laundry and for all wash temperatures. They are offered in the product forms of regular powders, granules, extrudates, tablets, bars, and liquids and pastes [1,2].

1. Heavy-Duty Detergents The world production of laundry detergents amounted to 24 million tons in 2000. Powders dominate worldwide (Fig. 1). Depending on product concept, manufacturing process, local standards, quality level, local regulations, and voluntary agreements, great differences are found from one formulation to another. Detergent manufacturers market laundry detergents, for instance, with and without phosphate in various regions and countries for ecological and regulatory reasons. (a) Regular Powders. Table 1 provides an approximate breakdown of regular detergent formulations for various regions and countries. In Europe, the recommended detergent dosages are between 3 and 8 g detergent per liter of wash water. In the Americas and Eastern and Southern Asia, values of 0.5–1.5 g/L are usual. (b) Compacts: Powders, Extrudates, and Tablets. The first major development to a new innovative product form was the ‘‘compacts’’ introduced in 1986 in Japan and then in Europe and the United States. The trend toward this product form caused by environmental responsiveness resulted in reduction of the amount of detergent being released into the environment as well as saving on packaging but it also contributed to the consumer’s convenience of having to handle lower volumes of household chemicals [3]. 1

2

Hauthal

FIG. 1 Types of detergents worldwide.

The transition from the regular powder to the compact dosage was possible through increasing the activity of the formulation by adding more surfactants, increasing bleaching power by replacing sodium perborate tetrahydrate with the more volume-effective monohydrate and later sodium percarbonate, and removing the fillers such as sodium sulfate because of an optimized manufacturing process. The regular hot-spray drying was complemented by densification steps such as roller compactation, wet granulation, or extrusion processes. Alternatively, nontower technologies such as agglomeration processes have been established. Thus higher bulk densities were achieved: for compacts, 0.75 kg/L; for the so-called supercompacts (since 1992), 0.8–1.0 kg/L. Consumers very quickly accepted the new product forms of compacts and supercompacts (second-generation compacts), but after initial success their market share in most countries has remained constant or, especially in Europe, actually declined (Fig. 2) [4]. Extrudates are an unconventional form of second-generation compacts that allow bulk densities of about 1.4 kg/L. The extrudates are marketed as dust-free spherical particles of uniform size (MegapearlsR). At the end of 1997, laundry tablets (‘‘tabs’’) were introduced in Europe following the market success of autodish tablets since the early 1990s and gained considerable market shares. But at the beginning of the new century, growth is to be seen for liquids and, to some extent, for regular powders. The development of tablets has caused the demand on new ingredients such as disintegrants for fast dissolution of actives [5]. The disintegration time of the tablets depends also on the composition of the surfactants in the formulation [6]. Furthermore, carefully designed branching of the hydrophobic part of surfactants is suitable to overcome the gelling of nonionics during tablet disintegration [7]. The typical composition of compact detergents [8] and heavy-duty detergent tablets is given in Table 2.

Fragrance

+/
5–15

+ 5–15

20–35

–

0–1 5–30

0.1–0.3

0.3–0.8

– –

– 0.5–1

– –

18–25 40–55

South America

0.1–0.3

0.3–2

– –

0–3 1–2

0–5 0–10

10–25 40–65

United States

+/
5–15

0–30

0–1.5

0.1–0.3

0.3–2

0–1 0.1–4

1–7 0–1

3–8 8–15

10–25 30–55

Europe

Composition (%)

+ 5–15

20–40

–

0.1–0.2

0.3–0.8

– –

– 0.5–1

– –

8–18 30–50

China, India

+ 5–15

5–15

–

0.1–0.2

0.3–1.5

– –

0–3 0.5–1

0–5 0–6

25–40 40–55

Japan

LAS = linear alkylbenzene sulfonate; FAS = fatty alkyl sulfate; FAE = fatty alcohol ethoxylate; TAED = N,N,NV,NV-tetraacetylethylenediamine; NOBS = nonanoyloxybenzenesulfonate; CMC = carboxymethyl cellulose. Source: Ref. 2.

Fillers/processing aids Minors Water

Fluorescent whitening agents Soil repellents

Enzymes

Bleach activators Antiredeposition agents Stabilizers Foam regulators

Phosphonates Soap, silicone oil, and/or paraffins Protease, amylase, lipase, cellulase Stilbene, biphenyldistyryl derivatives Poly(ethylene glycol terephthalate) derivatives Sodium sulfate

LAS, FAS, FAE Zeolite, sodium triphosphate, sodium citrate, sodium silicate, sodium carbonate/bicarbonate Sodium polycarboxylates Sodium perborate, sodium percarbonate TAED, NOBS CMC, cellulose ethers

Surfactants Builders

Cobuilders Bleaching agents

Examples

Ingredients

TABLE 1 Powder Heavy-Duty Detergent Formulations

Types and Typical Ingredients of Detergents 3

4

Hauthal

FIG. 2 Laundry detergents: Product forms in Europe. (Courtesy of S. Metzger-Groom, Procter & Gamble Eurocor, Strombeek-Bever, Belgium.)

TABLE 2 Typical Composition of Heavy-Duty Compact Detergents and Detergent Tablets on the European Market Detergent tablets Ingredient Surfactants Zeolite Pentasodium triphosphate Sodium polycarboxylate Layered silicate Bleaching agents Bleaching activator (TAED) Enzymes Antiredeposition agents (CMC) Corrosion inhibitors (sodium silicate) Stabilizers (phosphonates) Defoamers (soap, silicone oil, paraffins) Fluorescent whitening agents Disintegrants Source: Refs. 2 and 8.

Compact detergent, zeolite-based (%)

Zeolite-based (%)

Phosphate-based (%)

10–25 25–40

10–20 3–8 0.5–2 0–1

13–18 11–25 – 2–3 0–9 13–15 3–7 2–4 +

15–18 – 25–47 2 – 12–16 4–7 2–3 +

2–6

+

+

0–1

+

+

0.1–2

+

+

0.1–0.3

+

+

–

5–17

0–12

3–8

Types and Typical Ingredients of Detergents

5

TABLE 3 Disintegration Systems in Laundry Tablets Disintegration system Swelling agent

Wicking agents Effervescents Water-soluble salts

Ingredient Cross-linked PVP Compact cellulose Cross-linked polyacrylates Microcrystalline cellulose Sodium bicarbonate/citric acid Sodium acetate, sodium citrate

Disintegration systems are shown in Table 3. A balance is to be hold in view of tablet stability vs. dissolution rate. Higher compression strength means reduced dissolution rate. A ‘‘soft core’’ plus coating leads to increased complexity for tablet manufacture, and stability additives such as binders and polycarboxylates have also an impact on dissolution [7]. (c) Heavy-Duty Liquids. In the United States, liquid detergents have been common since the 1970s [9]. Today, the U.S. market is the largest single market of liquid heavyduty detergents (HDL) in the world (market share some 50% in 2000). On the European market, HDL have shown a considerable growth in the last years. Heavy-duty detergents are marketed mainly without builders (unstructured). Typical European formulations are shown in Table 4. Structured liquids could not achieve a commercial breakthrough. Liquid detergents with builders typically contain 15–30% surfactants; the total amount of surfactants in products without builders can be as high as 50%. Besides having a high content of synthetic surfactants, they include a large proportion of soap with a defined chain length as a water-softening component, as well as ingredient needed as formulation aid. The total content of

TABLE 4 Composition of Liquid Heavy-Duty Detergents in Europe (2000) Ingredient Anionic surfactants Nonionic surfactants Soaps Builders Solubilizers Alcohols Enzymes Fluorescent whitening agents Stabilizers Fragrances Minors, water Source: Ref. 2.

Unstructured (%)

Structured (%)

7–18 15–30 10–22 0–8 0–12 8–12 0–2.5 0.05–0.25

10–25 6–10 4–6 15–30 0–5 0–5 0–1.5 0.05–0.25

+/
+ 30–50

+/
+ 30–50

6

Hauthal

washing active substances can be as high as 60%. HDL show a steady trend toward a higher enzyme content and incorporation of more types of enzymes. Bleaches are not compatible with liquid detergents. New product forms of heavy-duty liquid detergents are gel-like pourable concentrates with higher viscosities (1500–3000 mPa s) than conventional HDL (250–300 mPa s) that show improved performance in pretreating stains [10], and the so-called liquid tabs (sachets) that deliver convenience to the consumer who has no dosage problem anymore. The liquids are enclosed in a water-soluble film, which consists of, for instance, poly(vinyl alcohol) [11]. (d) Added Value in Detergents. Besides the new disintegration systems for detergent tablets, new ingredients offer a challenge for detergents of the 21st century [12]. A recent example is the development of laundry detergents that wash UV protection into the clothing [13]. The UV absorbers in the formulation are fixed like a colorless dye on the garments. After repeated wash cycles, a UV Protection Factor (UPF) of 30 can be achieved.

2. Specialty Detergents Specialty detergents comprise products for delicate and colored laundry (without bleach and fluorescent whitening agents; cellulase is added in most, dye transfer inhibitors in some formulations), for woolens (low-temperature laundry, short washing times, high bath ratios, avoiding vigorous mechanical action), for curtains, and for washing by hand. High-foaming detergents for washing by hand are intended for washing small amounts of laundry in a sink or in a bowl. Because of the increased number of household washing machines, the use of these specialty detergents has been declining but gaining a market niche as travel products. Liquid products are the preferred form of specialty detergents that are intended for washing machine application. Detergents for woolens may be free of anionic surfactants. In this case, they contain combinations of cationic and nonionic surfactants. The cationics act as fabric softeners to help keep wool soft and fluffy. Liquid detergents for black garments have been developed to meet recent fashion needs. Their formulations ensure that after wash, the black color of the clothing shows no fading.

3. Laundry Aids Laundry aids comprise pretreatment aids (prespotters, water softeners), boosters, and aftertreatment aids (fabric softeners, stiffeners, laundry dryer aids, refreshing products for dryer application, and odor removers). (a) Pretreatment Aids. Soil and stain removers (prespotters) in the form of pastes, sticks or aerosols, or in trigger spray bottles help removing greasy and/or bleachable stains. Surfactants and solvents or solubilizers are a major part of their formulations. Although the great majority of heavy-duty laundry detergents contain sufficient builders and cobuilders to prevent buildup of lime deposits upon multicycle washing, even in hard water, water softeners are still used both in the United States and in Europe. European water softeners generally contain ion exchangers such as zeolite A and polycarboxylates, and sodium silicate. Special presoaking agents that were frequently used in the past have gradually lost their market relevance in the industrialized countries.

Types and Typical Ingredients of Detergents

7

(b) Boosters. To remove or pretreat stains on washing, today soaking with fine or heavy-duty detergents (formerly special soaking products) or the application of bleach boosters dominate. In special cases, liquid or pasty stain removers mentioned above are also used. As an independent product group, bleach boosters have been developed from the bleach component of the so-called unit construction systems once anticipated as environmentally favored detergents but not accepted in the marketplace to a greater extent. The typical composition of bleach boosters is given in Table 5. Powder or tablet bleaching products generally contain sodium perborate or sodium percarbonate, whereas most liquid bleaching agents are diluted solutions of sodium hypochlorite (for whites only) or hydrogen peroxide. In the United States, the so-called laundry boosters are also marketed. The formulations contain either sodium silicate, sodium citrate, sodium borate, or sodium carbonate, usually in combination with surfactants and enzymes as well. (c) Aftertreatment Aids. Aftertreatment of washed fabrics is aimed at restoring textile characteristics that have suffered in the course of laundry. Depending on the fabric involved, the products in this category have to provide elastic stiffness, improved fit, and body (shirts and blouses); smoothness, sheen; good drape (curtains); fluffiness and softness (underwear, towels, bath gowns); or antistatic properties (garments, underwear, hosiery, and other easy-care articles made from synthetic fibers). Fabric softeners and conditioners. Because of the mechanical stress in the washing machine and subsequent drying indoors in static air, many fabrics get a harsh feel. Addition of a liquid fabric softener in the final rinse results in fabrics that feel softer. This is caused by adsorption of the active ingredient, a quaternary ammonium salt with two hydrophobic groups. This application of fabric softeners is typical for Europe, Japan, and other regions of the world. In the United States, laundry is mostly dried in mechanical dryers. The tumbling of the laundry in the dryer accomplishes its own softening effect. The main task of U.S. fabric softeners is to impart antistatic properties and a pleasant odor to the garments. Therefore fabric softeners are frequently applied as sheets made from nonwoven material and impregnated with active material (laundry dryer aids).

TABLE 5 Typical Composition of Bleach Boosters Ingredients Sodium percarbonate TAED Anionic and nonionic surfactants Builders (soda, silicates, polycarboxylates) Organic complexing agents Enzymes (amylase, protease, lipase) Source: Ref. 3.

Content (%)

Function

15–40 5–15 5–15 15–30

Bleaching Bleach activator Wetting Water softening, cleaning performance Destruction of soil matrix Stain removal

5–10 0–5

8

Hauthal

Typical formulations of fabric softeners are given in Table 6. Because of its poor biodegradability, the formerly used distearyldimethylammonium chloride (DSDMAC) has been replaced with the so-called esterquats [14], cationics with predetermined breaking points for hydrolysis, and subsequent biodegradation. Fabric softeners have additional benefits (fabric conditioners) [15]. They impart good antistatic properties and a pleasant fragrance to the fabrics. They make fabrics easier to iron and help reduce wrinkles in garments. They reduce drying times, saving energy when softened laundry is tumble-dried. More recently, it has been shown that caring silicone additives used in hair-care applications can improve the caring properties of today’s fabric softeners [16]. Transparent fabric softeners are also a new development. This is achieved by using esterquats that bear unsaturated hydrophobes such as oleyl groups at the quaternary nitrogen [17]. Besides the specialty detergents for woolens, the incorporation of cationic fabric softener (conditioner) actives into laundry detergents that do not contain anionic surfactants could not achieve a notable market share. Stiffeners. If stiffness and body are desired rather than soft and fluffy laundry, stiffeners can be added as aftertreatment. Formulations for this purpose include natural starch derived from rice, corn, or potato, which can be used to impart extreme stiffness to fabrics. Alternatively, synthetic polymeric stiffeners such as poly(vinyl acetate) impart a more modest degree of stiffness. The products are offered as dispersions or aerosol sprays. Refreshing products and odor removers. In the late 1990s, refreshing products for dryer application were introduced in the United States and Europe. They are not aimed at replacing professional dry cleaning but allow the consumers to refresh their garments any time at home. The refreshing action is achieved inside the tumble dryer by using a moist impregnated sheet along with the garment to be treated. Some systems include a plastic bag for producing a damp microclimate inside the dryer whereas other systems do not. In both cases, the water vapor removes malodors. Furthermore, a spot cleaning can be achieved by the moist sheet or a separate liquid stain remover used in combination with an absorbent layer of cloth or paper. Liquid odor removers introduced in the United States in 2000 are based on cyclodextrins, which form inclusion compounds with malodor molecules, and directly dispensed into the washer.

B. Dishwashing Products Dishwashing products are classified into hand dishwashing detergents and automatic dishwashing agents. In everyday life, ‘‘automatic dishwashing agent’’ stands for the cleaner component. The automatic dishwashing product system comprises also the rinsing aid, the ‘‘salt’’ for the regeneration of the ion exchanger to manage the water hardness, the machine care component, and the deodorant. Besides the single components, there are 2-in-1 and 3-in-1 products in the marketplace (Fig. 3). In 2-in-1 products, cleaner and rinse aid are combined; 3-in-1 products additionally contain a salt substitute, mostly polycarboxylates. Both product groups, hand and automatic dishwashing products, differ fundamentally in their composition and delivery forms. The surfactant-rich hand dishwashing detergents show a neutral or weakly acid pH value (because of a practically

11–20 0–2 0–3 0–4 0–0.3 0–0.2 – + 0.5–3 – 0–0.6 ad 100

0.2–2.5 – 0–0.2 ad 100

Concentrate

3–11 0–2 0–0.8 0–1 0–0.5 0–0.2 – +

Regular

0.5–4 0–12 0–0.7 ad 100

11–26 0–2 0–3 0–4 0–0.1 0–0.2 0–6 +

Conditioner

0.2–2.5 – 0–0.2 ad 100

3–11 0–2 0–0.8 0–1 0–0.5 0–0.2 – +

Regular

0.5–3 – 0–0.6 ad 100

10–30 0–2 0–3 0–4 0–0.3 0–0.2 – +

Concentrate

United States

0.5–4 0–15 0–0.7 ad 100

15–35 0–2 0–3 0–4 0–0.1 0–0.2 0–6 +

Conditioner

0–3 0–10 0–0.5 ad 100

0–5 +

0–20 0–5 0–5 0–1 0–2

Japan

Esterquat type: Triethanol amine, diethanol amine, or epichlorohydrine esterified with tallow-based acids or oil-based acids are preferred in Europe. Diesters are preferred because of their superior softening performance. Aside from esterquats, DSDMAC types, imidazolines, and amino ester salts are used in some countries. b Fatty alcohols, fatty acids, triglycerides. c Silicone oils, dispersed polyethylene. d Magnesium chloride, calcium chloride, sodium chloride, sodium acetate. Source: Ref. 2.

a

Esterquat Aminoamides Nonionics Other softenersb Preservatives Dye fixatives Ironing aidsc Dyes, fragrances Solvents Ethanol, isopropanol Glycols Viscosity regulatorsd Water

a

Ingredient

Europe

Content (%)

TABLE 6 Formulation of Fabric Softeners in Europe, the United States, and Japan

Types and Typical Ingredients of Detergents 9

10

Hauthal

FIG. 3 Automatic dishwashing detergents: tablet forms.

daily skin contact) and are predominantly marketed in liquid form whereas the solid automatic dishwashing cleaner tabs give strongly alkaline solutions in the dishwasher [18].

1. Hand Dishwashing Detergents Hand dishwashing detergents are aqueous solutions of different surfactant mixtures and contain additives such as perfumes, coloring agents, and auxiliaries, for instance, for the adjustment of viscosity. A typical formula for hand dishwashing detergents is given in Table 7. Cleaning power [19], hygiene contribution, and skin compatibility are in the focus of the performance profile. Ready biodegradability and low cost are prerequisites for market success. Mildness gains more and more priority in all future product development. Modern formulas are based on a combination of fatty alkyl ethoxy sulfates (also alkyl sulfates or alkanesulfonates, formerly even alkylbenzene sulfonate), alkyl polyglucosides, and/or cocoamidopropyl betaine. A lot of especially skin-friendly surfactants and care components such as cocoamidoamphoacetates, plant protein hydrolysates, or aloe vera extracts can be added. Recently, lactates are recommended as skin-friendly ingredients in hand dishwashing [20].

2. Automatic Dishwashing Products Today, in the United States, 53% of households own a dishwasher. The average across Europe is 33% (4% in Poland, 53% in Germany). Water hardness is much lower in North America (7j H average) than in Europe (12j H). Because a dishwasher is much more expensive in Europe, this machine is still perceived as a luxury item, whereas in the United States it is seen as a necessity. In North America, consumer’s pretreatment of dishes is 79% (Europe: 39%) as they have more problems with starch, grease, and grit. The unsatisfactory end result is spotting and lack of shine. European automatic dishwashing detergents still have a more complex (and expensive) chemistry to solve these problems [21]. Automatic dishwashing caused completely new demands on dishwashing agents. Compared to hand dishwashing, the weighing of the cleaning factors has changed. Hand dishwashing implies a great importance of mechanical energy. In contrast, chemistry is crucial for automatic dishwashing added by thermal energy and time of action. The first products consisted of about 95% pentasodium triphosphate (‘‘phosphate’’), 3% sodium metasilicate to enhance alkalinity, and sodium trichloroisocyanurate as a bleach agent. These formulations contained no surfactants. Because of

Types and Typical Ingredients of Detergents

11

TABLE 7 Typical Composition of Hand Dishwashing Detergents Content (%) Ingredients

Conventional

Concentrate

Function

10–25

25–40

Wetting of dishes and soil, dissolution and solubilization of fat and other impurities

0–7

0–10

Adjusting pH value Avoiding phase separation

0–2

0–3

Refatting of skin

0–1

0–1

Product aesthetics, differentiating products in the marketplace

0–0.1 0–0.1

0–0.1 none

10–25

25–40

0–5

0–5

Skin care

0–2

0–3

Reduction of germs (in case of concentrated application)

Surfactants Alkanesulfonates Alkylbenzene sulfonates Fatty alkyl ether sulfates Fatty alkyl sulfates Fatty alkyl ethoxylates Alkyl polyglucosides Amine N-oxides Cocoamidopropyl betaine Citric acid Solubilizer Cumene sulfonate Alcohol Refatting aids, e.g., fatty acid amides Fragrances

Coloring agents Conservation means

Especially skin-sensitive preparations Selected skin-compatible surfactants Fatty alkyl ethoxy sulfates Alkyl polyglycosides Cocoamido propyl betaines Additional care components, e.g., protein hydrolysates and/or aloe vera Antibacterial preparations Additional antibacterial actives, e.g., sodium benzoate or salicylate Source: Ref. 18.

Protecting against microorganisms

Skin protection and care

12

Hauthal

ecological pressure, the phosphate was then reduced to 30% and replaced stepwise with sodium metasilicate. More ingredients such as surfactants, polymers, coloring agents, and fragrances were added. In 1991, the first phosphate-free, low-alkaline automatic dishwashing agents were introduced in Germany. Furthermore, the chlorine-containing bleach was changed to the sodium perborate/TAED system proven in laundry detergents. Although the supposed diminished cleaning performance was partially compensated by enzymes, the quality of the new phosphate-free products was bad compared to the conventional products. Colored residues (tea), lime scaling, silver turning, more rust on stainless steel, and glass corrosion occurred. Already in 1995, leading dishwasher producers recommended to return to phosphate-containing automatic dishwashing cleaners. A comparison of different automatic dishwashing cleaners is shown in Table 8 [22]. Some years ago, methods for ascertaining their cleaning performance were developed [23].

TABLE 8 Typical Composition of Automatic Dishwashing Cleaners Cleaner granulate Ingredients Pentasodium triphosphate Trisodium citrate Sodium disilicate (alternatively) Layered silicate Sodium carbonate Sodium bicarbonate Sodium polycarboxylates Acrylic/sulfonic acid copolymer Sodium perborate monohydrate Sodium percarbonate (29 wt.%) Bleach activator TAED Sodium phosphonatea Low-foaming nonionics Amylase, protease Poly(ethylene glycol)b Silver protection (benzotriazole) Fragrances pH value (1 wt.% solution) a

Tablets

Phosphate-based, content (%)

Phosphate-free, content (%)

Phosphate-free, content (%)

Phosphate-based, content (%)

45–60 – 2–8

– 20–30 2–8

– 30–40 –

45–60 – 2–10

7 15–25 – 2–5 0–2

7 15–25 – 4–8 –

– 5–10 20–30 4–8 –

7 15–20 – 2–5 0–2

–

–

8–12

8–12

10–15

10–15

–

–

2–4 – 1–2 1–1.5 – 0.25–0.5

2–4 0.5–1 1–2 1–1.5 – 0.25–0.5

2–4 0.5–1 1–2 1–1.5 3.5 0.25–0.5

2–4 0–0.2 1–2 1–1.5 0.2–1 0.25–0.5

–

+

+