Shrink resist finishes

Although the present situation and the way ahead appear uncertain, it is clear that enzyme treatment alone does not fulfil the technical requirements for shrink-resist finishing. Even with enzyme treatment, some degree of chlorination (with the attendant AOX problems) and/or application of a resin will still be required. Two-stage or even three-stage processes have been proposed [116] ... 

Although chlorination with sodium dichloroisocyanurate is still by far the most commonly used method of shrink-resist finishing, there is considerable concern over the environmental influence of its AOX contribution. For this reason, its usefulness could decline in future and there has been considerable investigation of alternatives to this attractively cost-effective treatment. 

Polysiloxanes as shrink-resist finishes have been developed from their traditional uses as softeners and water repellents as such their chemistry is discussed in section 10.10.3. This was a natural trend as many shrink-resist finishes tend to impart a harsh handle to wool. 

Highly concentrated, low formaldehyde glyoxal based reactant for durable press and shrink resistant finishing. 

Sodium bisulfite-blocked isocyanate-terminated prepolymers are extensively used as shrink-resistant finishes for wool. Polycarbamoylsulfonates (PCS) are produced from NCO-terminated prepolymers with bisulfite salts in aqueous alcohol as the solvent, shown schematically as follows (78-80) ... 

Textile Finishing. Polyethyleneimine-A/-methylolurea derivatives improve the crease and wear resistance of cotton (429,430). The adhesion between individual wool fibers is improved by pretreatment with amines, which leads to improved shrink resistance (431). An antimicrobial finish can be appHed to cotton by using a combination of PEI and ureas to bind zinc pyrithione to the fabric (432). After wool has been provided with a flameproof finish using fluorozirconate or fluorotitanate, the wool can be neutralized with PEI (433). Conventional neutralizing agents caimot be used for this purpose since they impair the flameproof characteristics of the impregnated fabric. 

No shrink-resist polymer developed so far meets all the above requirements [301]. There is clearly some similarity with easy-care finishing of cotton. Although effective crosslinking agents are readily available for application to cotton, the morphological complexity of the wool fibre is such that an equally effective polymer has yet to be identified for wool treatment [304]. 

Urea—formaldehyde and melamine—formaldehyde reagents are resin formers, which not only cross-link cotton but also copolymerize with themselves. These have been used both as simple cross-linkers or prepolymer systems. If too much of the polymerization is concentrated on the fiber surface, the fabric may be sufficiendy stiffer that it takes on a boardy character. As such, the finisher must control the action of agent to give the desired crisp hand but prevent the development of boardiness. Melamines have been recommended for applications when complete shrink resistance is required. However, both finishes were rejected for the white-shirt market because of loss of strength when hypochlorite bleach is used on account of vulnerable NH groups and the ensuing discoloration (37). 

The washing test applied to the first five was that of the I.S.O. (Mechanical Mild Wash at 40°C (104°F) for 30 minutes) and for the remainder the S.D.C. No. 2 test (50°C (122°F) for 45 minutes. The figures show that there is a loss of fastness of 1 to 2 gradings with the level-dyeing acid dyes, but none with the premetallized or fast acid dyes. Different unshrinkable finishes would not give exactly the same results but they could be expected to be of the same order. Shrink-resisting processes are usually applied to goods which are washed frequently, and it follows that the use of the molecularly-dispersed acid dyes is undesirable. 

Dura Flex. [SchoUer] Cyclic nitrogen compd. celiulosic reactant for wash/ wear, crease resistant and shrink control finishes. 

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