Stain-resistant agent

A stain-resist agent contains phenolic, sulfonic, or carboxylic groups needed for attachment to nylon fibers and stain prevention. 

Type of fibers and heat-setting history Stain-resist agent and its chemical and physical properties Application process for the stain-resist agent Fluorinated soil retarder... 

Coffee stain has remained a formidable challenge, A protective fluorinated finish retards the diffusion of the stain into fibers. However, when coffee penetrates the fluorinated repellent finish, stain-resist agents in the fibers must hinder staining by coffee. 

Discoloration of a textile by a stain involves the same physical-chemical interactions which govern the sorption of a textile dye by fibers. Hence, staining can be described as an unwanted dyeing process. Consequently, the objective of a stain-resist agent is to prevent dyeing of fibers by any colored species which may con-... 

The first defense line against staining is the fluoiinated soil retardant (see Chapter 13) which reduces soiling with particulate soil and hinders wetting of fibers. When a liquid is spilled on the carpet, the fluorinated repellent provides time for the removal of the liquid by blotting before the liquid wicks into the carpet. However, if the liquid is allowed to wick into the carpet, a stain-resist agent in the fiber surface or inside the fibers must prevent staining. 

When it was recognized that fluorinated soil retardants alone cannot provide a complete protection against staining with liquids, the fibers were treated with stain-resist agents. 

Stain-resist agents related to syntans are condensation products of formaldehyde with aromatic compounds, including phenols, 4,4 -diphenyl sulfone, p-phe-nolsulfonic acid, sulfonated naphthalene, and sulfonated bisphenol (Fig. 14.7). The condensates contain sulfonic acid groups or are sulfonated after the condensation reaction [44-54]. A polycondensation of a phenolsulfonic acid with formaldehyde may involve desulfonation and consequent cross-linking [55]. Because the condensation reactions are complex, the formaldehyde condensates used as stain-resist agents are mixtures of several components [56]. 

Stain-resist agents containing a formaldehyde condensate of mainly bishy-droxyphenyl sulfate and the remainder of cresol, methyl p-hydroxybenzoate, or p-... 

The yellowing problem was finally solved by stain-resist agents based on polycarboxylates, such as hydrolyzed maleic acid copolymers with styrene [60] (Fig. 14.8), with butadiene [61] and an allyl or vinyl ether [62,63]. The low affinity of polycarboxylate copolymers to nylon in neutral and alkaline medium re-... 

Usually, the stain-resist agent is applied to the dyed carpet, either by exhaust application in a dye beck or mainly by a continuous process, by using the Kiister Flex-Nip equipment, by spraying, or as foam. The stain-resist agent is sorbed onto the fibers by a steaming or heating. 

The concentration of the stain-resist agent on fibers is determined by dissolving nylon fibers in concentrated sulfuric acid [30] or in formic acid and measuring the absorbance at 260 nm in the ultraviolet region. Because a stain-resist agent is a mixture of various components, some of which are sorbed on fibers preferentially, only an approximate average value can be obtained. 

Stain-resistance tests have two different objectives (1) to control the quality of the soil-resist treatment, to assure that specifications are met and control the proper operation of the application process, and (2) to evaluate the effectiveness of developmental stain-resist systems. Whereas quality control requires mainly a pass or no-pass result, quantitative data are needed for research and development. Small differences in stain resistance reveal trends related to variation of the stain-resist agent structure, active concentration, and application conditions. Hence, the objectives of stain-resist tests can be quite different. 

The amount of dye sorbed as a function of stain resistance is shown in (Fig. 14.13). The precision of the stain resistance test measuring dye sorption by the depletion technique was determined using eight replicate samples of a white level-loop carpet, treated with a small amount of a stain resist agent. The average dye sorption was 60.9% (2.40 mg/g) and the standard deviation was found to be... 

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