Crease resistance

High molai mass polyuiethanes weie obtained from condensation of 4,4 -(hexa luoioisopiopylidene)bis(phenylchloiofomiate) with various diamines (125). These polymers could be cast into transparent, flexible, colodess films or spun into fibers which showed promise as crease-resistant fabrics. Other polyurethanes discovered are good candidates for naval and aerospace apphcations (126). 

It is generally accepted that, all other things being equal, the lower the secondary creep, the better the fiber is in terms of wear, shape retention, and crease resistance. This does not mean that glass, which has no secondary creep, is better in abrasion resistance than high tenacity viscose rayon, which has secondary creep, because the respective energy absorption capacities of these two materials, exclusive of secondary creep, are not equal. Nor does it mean that fibers that exhibit secondary creep are of no value. For fabrics to meet the requirements of wear, crease resistance, and shape retention, the load and extension yield points should not be exceeded during use. 

The polycarbamylsulphonates are water-soluble reactive bisulphite adducts of polyisocyanates and are being investigated as possible materials to render woollen fabrics crease-resistant. 

In general, grafting of hydrophillic monomers have been found to lead to an increase in wettability, adhesion, dyeing, and rate of release of oil stains by detergent solution. On the other hand, if the monomer is hydro-phobic, the result will be decreased wetting by all liquids including oil stains. If grafting is not restricted to surface alone but encompasses the bulk of the backbone polymer, then the properties such as flame resistance, water sorption, crease resistance, etc. will be affected. 

Dyeing polyester/cotton with reactive and disperse dyes and imparting a crease-resist finish [327]. 

The earliest polymeric cationic aftertreatments stemmed from the development of crease-resist finishes for cellulosic fibres. One such, promoted specifically for its colour fastness improvements when applied as an aftertreatment to direct dyeings, was a condensation product of formaldehyde with dicyandiamide (Scheme 10.82). Many similar compounds followed, such as condensation products of formaldehyde with melamine (10.212), polyethylene imine) with cyanuric chloride (10.213) and alkyl chlorides with polyethylene imine) (10.214 R = alkyl). 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

The carboxylated polymers [476,499] include acrylic, methacrylic or maleic acid polymers (all obviously anionic in character) applied mainly from aqueous emulsion and particularly in combination with crease-resist or durable press resins. This type of chemistry has already been discussed in section 10.8.2. A particularly common example is the copolymer of acrylic acid with ethyl acrylate (10.247). In general the best balance of properties is obtained with 75-85% ethyl acrylate (y) and 25-15% acrylic acid (x), with an average chain length of about 1300 (x + y) units 65-85% ethyl acrylate with 35-15% methacrylic acid is also suitable. When the content of the acidic comonomer increases above about 30% the durability to washing tends to decrease, whilst longer chains tend to give a stiffer handle [499]. 

Melamine resins also are used for the production of decorative laminates. The amino resins are able to modify textiles like cotton and rayon by imparting crease resistance, stiffness, shrinkage control, fire retardance and water repellency. They are also used to improve the wet strength, rub resistance and bursting strength of paper. 

The oxidation-drying printing inks have to meet high chemical and physical requirements. Besides resistance to various solvents, detergents and wash liquors, they also need to have high lightfastness, rub resistance and crease resistance. 

One of the larger uses of nylon fibers is tire cord. In apparel applications, which are another major area, permanent press can be achieved by heat treatment. This crease resistance lasts until abrasion, hear, or pressure wears down the molecule orientation. Since it is strong and lightweight, nylon also is used for rope, parachutes, and some undergarments. 

These are the polycondensation products of dlcarboxylic acids and diols. Dacron or terylene Is the best known example of polyesters. It is manufactured by heating a mixture of ethylene glycol and terephthallc acid at 420 to 460 K In the presence of zinc acetate-antimony trioxlde catalyst as per the reaction given earlier. Dacron fibre (terylene) is crease resistant and is used In blending with cotton and wool fibres and also as glass reinforcing materials in safety helmets, etc. 

Both are softer than rayon but not so strong, have poor crease resistance, and are not coloifast. 

Urea- and melamine-formaldehyde resins are used as moldings, lacquers, and adhesives (for wood), also as textile additives (increased crease resistance) and paper additives (improved wet strength). 

The recent industrial applications of carbamates as a tranquilizer [1 ] (structure III), a crease-resistant agent (when reacting with formaldehyde) in the textile industry [2], a solvent [3], hair conditioners [4], a plasticizer [5], and a fuel additive [6] have stimulated interest in the synthesis of various carbamates. 

Eponite" 100. Shell Chemical Co trademark for a water-dispersible liquid epoxy resin used in textile industry to impart crease resistance, shrinkage, etc Ref CondChemDict(1961), 444-R... 

Tetrakis(hydroxymethyl)phosphonium salts are used to produce crease-resistant and flame-retardant finishes on textile fabrics, including children s nightwear. No data on occupational exposure levels were available (lARC, 1990). 

Melamine and its polymers have uses in many industrial fields. The commercial importance of the compounds is shown by the fact that 34 x 106 kg of melamine was produced in the USA in 1970. The chemistry of the melamine resins has been discussed already (see Chapter 1.11). The major uses of the resins are in the formation of high-pressure laminates for home furniture, and as moldings for crockery. In addition the resins are used in finishing textiles, to improve crease resistance, and as coatings for wet strength paper. 

PERMANENT-PRESS RESIN. A thermosetting resin used as a textile impregnate or fiber coating to impart crease resistance and permanent hot-creasing to suitings, dress fabrics, etc. Chemicals such as formaldehyde and maleic anhydride are the basis of these products. The resin is cured after the fabric has been tailored into a garment. A permanent-press fabric that requires no resin has been developed (a blend of polyester with cotton or rayon). 

Practically all synthetic fibers can be printed with disperse dyes. Cationic dyes are used preferentially for acrylic fibers, and acid dyes and metal-complex dyes can be used for prints on polyamide fibers. The importance of printing with disperse dyes and the relative amount of different man-made fibers used for prints varies according to fashion and local requirements. Polyester fabrics alone or in combination with cotton are the most important. After precleaning, fabrics made from synthetic fibers must be heat-set to achieve dimensional stability and crease resistance. The usual setting conditions are 20-30 s at 190-210°C, and for texturized articles about 30°C lower. 

As shown by the practical application of oligoalkylhydridesiloxanes, surface treatment of clothing cellulose textiles yields certain effects, the most important of which are shrink resistance, crease resistance and hy-drophobicity. 

Textile Treating. MF resins improve the crease-resistance of cotton and cotton-synthetic blends, stiffen synthetic fabrics such as nylon, protect fabrics from mildew and aid in water repellency. 

Series III Cross-Linking Resins. The third series of experiments attempted to create cross-links within the cellulose chains using resins traditionally used to impart crease-resistant properties to cotton and rayon fabrics (4,8). Fabrics treated with the materials in Table IV were prepared. 

Belmadur A process for strengthening wood by chemically crosslinking the cellulose fibers. This process enables relatively soft woods to be used in place of tropical hardwoods. The crosslinking agent is a complex polyol, similar to agents used for making textiles crease-resistant, hence the... 

Latex copolymers including NIBA have found applications in protective coatings, binders for nonwoven fabrics, water and oil repellancy, crease resistance, print pastes, leather finishing, adhesives, paper impregnation, curable thickeners and elastomers. (2B). Comonomers include acrylic and methacrylic esters, acrylo nTtrile, styrene, and occasionally vinyl acetate or vinyl chlorida... 

Reactive softeners Some softeners have functional groups that can react with the corresponding groups of some fibres, for example A-methylolated amines with the hydroxyl groups of cellulose (compare the mechanism of the crease resistance finish). The result is a very durable finish, combined with the typical advantages and disadvantages of this crosslinking chemistry, as discussed in Chapter 5. 

Elastomeric finishes are often combined with easy-care and durable press finishes. The silicones reduce abrasion, increase tearing strength (Ehnendorf testing apparatus - ASTM D1424), and crease recovery. For equal crease resistance and durable press performance the amount of cellulose crosslinking agents can be markedly reduced in these combinations. ... 

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