5.7 Evaluation methods
Evaluation methods for formaldehyde Qualitative test for the presence of formaldehyde in fabrics Quantitative test for formaldehyde in air Quantitative tests for formaldehyde in fabrics
disadvantages： Wrinkling after washing
The terms describe the finishing to overcome wrinkling after washing:
easy-care Minimum care easy-to-iron no-iron wash and wear crease resistant durable press permanent press shrink proof wrinkle resistant and wrinkle free
Different ways to call the same finishing. The difference is in the degree of anti-crease effect: easy care = light effect no iron = medium effect wash & wear = strong effect Of course the amount of applied resins increases from the first to the third one.
5
outline
5.1 Introduction 5.2 Mechanisms of easy-care and durable press finishing 5.3 Examples of textiles with easy-care and durable press finishes 5.4 Chemistry of easy-care and durable press finishes 5.5 Application methods 5.6 Compatibility with other finishes 5.7 Evaluation methods 5.8 Troubleshooting and practical problems
Commercial value increasing retail sales
However ,the most technically correct description would be cellulosic ‘antiswelling’ finishes or cellulosic ‘crosslinking’ finishes
5.4.2 Formaldehyde considerations
Harm of formaldehyde
irritates mucous membranes(黏膜), causes teary eyes, induces cough, and can lead to difficulties in breathing and headaches. Skin contact with aqueous solutions of formaldehyde or with textiles that contain a high level of formaldehyde can give rise to eczema (湿 疹)and occasional allergic reactions. In addition, formaldehyde is a suspected human carcinogen.
5.2 Mechanisms of easy-care and durable press finishing
WHY FABRICS WRINKLE? Why do some fabrics being easy to wrinkle and others don't?
moisture absorption
The main properties of DMDHEU-based products are: Low to very low reactivity (when ether modified) Excellent durability to laundering Low chlorine retention Medium to very low formaldehyde release The most commonly used durable press products.
5.3 Examples of textiles with easy-care and durable press finsy-care and durable press finishes
History of Crease Recovery The end of the 1920s saw the introduction of formaldehyde condensation products.Initially mainly urea–formaldehyde, soon followed by melamine–formaldehyde In 1947 dimethylolethylene urea Easy-care finishing of cotton has been a major market success since the middle of the 1950s. products that are very low free formaldehyde content as well as completely formaldehyde free
Melamine–formaldehyde (M/F) products Better stability to hydrolysis and better washing durability than U/F products Relatively high formaldehyde content and release Fewer problems with chlorine retention than U/F products More dimensional stability and stiffness (also for nylon and polyester).
polycarboxylic acids
5.4.5 Catalysts for easy-care and durable press finishes
MgCl2, alone or blended with an organic acid sodium hypophosphite
5.4.4 Miscellaneous crosslinking agents
5.1 Introduction
Cellulose fibres and especially cotton are still the most important kind of fibres, because of their numerous advantages advantages：
？
An unavoidable side effect of the cellulosic crosslinking finishes is a reduction in the elasticity and flexibility of the cellulose fibres. This produces a considerable decrease in abrasion resistance and tear and tensile strengths on natural cellulose
The primary effects of the easy-care and durable press finish on cellulosic fibres are ☺ reduction in swelling and shrinkage ☺ improved wet and dry wrinkle recovery, smoothness of appearance after drying, ☺ and retention of intentional creases and pleats.
N,N'-Dimethylol-4,5-dihydroxyethylene urea (DMDHEU) was once the chemical basis of about 90 % of the easy-care and durable press finish products on the market.
Wool and cotton fabrics Wrinkle more resistive to wrinkling both fibers absorb water absorb less water Polyester and nylon fabrics
Lateral Forces Between Cellulose Chains
＊dimethylol ethylene or propylene urea, ＊diglyoxal urea ＊ triazons ＊ urons ＊ carbamates ＊ diepoxides ＊and diisocyanates
5.5 Application methods
机、针织物树脂整理的不同设备组合
Free Formaldehyde on the fabric = < 300 p.p.m. Free formaldehyde on the fabric = < 75 p.p.m Free formaldehyde on the fabric = ZERO