Shrink-Resist Treatments for Wool Using Multifunctional Epoxides

Abstract

An attempt was made to render wool fibers shrinkproof without causing any damage to the hydrophobic nature of the scale surface. To this end, wool fibers were treated with a water soluble multifunctional epoxide, i.e., glycerol polyglycidyl ether (GPE) in concentrated salt solutions, where the prominence of scale edges was depressed. The role of GPE is not to chemically modify the fiber surface, but to crosslink the cuticular cells to prevent their edges from prominence in aqueous media. Excellent shrink resistance can be imparted to wool by applying GPE in saturated NaCl solution in the presence of a reductive agent such as Na 2 S 2 O 5 , while the hydrophobic nature of the surface remains unchanged.The felting shrinkage of assemblies of wool fibers is based on the directional frictional effect; in other words, the coefficient of friction in the root-to-tip direction is different from that in the tip-to-root direction [7]. Many methods have been developed for preventing shrinkage of wool fibers, and they can be classified into three main categories. The first is coating with resins such as polyamide epichlorohydrin or grafting polymers onto wool fibers [ 1,3,4,14]. The second is morphological modification of the cuticular cells by chemical or physical treatment [2,8,13]. The third method is to impart additional crimp in wool fibers [ 12], but this method is not sufficient to render wool fibers completely shrinkproof. No satisfactory method has been developed to make wool fibers shrink resistant without damage to the hydrophobic nature of the surface.In this study, we attempted to reduce the directional frictional effect of wool without damaging its hydrophobic nature by treating it with a water soluble multifunctional epoxide, i.e., glycerol polyglycidyl ether (GPE), which is available on an industrial scale. The role of the multifunctional epoxide in this treatment is to modify not the fiber surface but the cuticular cells by crosslinking, so as to prevent their edges from prominence in aqueous media. At the same time, the treatment immobilizes the intercellular cement in the cell membrane complex, which contributes to the hydrophilic nature of wool. To this end, we treated wool fibers with GPE in concentrated salt solutions, where the directional frictional effect of wool is known to be depressed. ExperimentalThe wool was Australian Shropshire (32.9 ~.m) and Merino (21 ~cm). GPE (Denacol EX 313) was purchased from Nagase Chemicals Co. Ltd., Osaka. The chemical formula of GPE is shown in Figure 1. All FIGURE 1. Chemical formula of glycerol polyglycidyl ether (GPE) used.

Shrink-Resistant Properties and Surface Characteristics of Wool Fibers Treated with Multifunctional Epoxides

“…These results show that effective crosslinking formed between the molecules contained in the CMC of the GPE treated wool fibers, particularly in the fibers treated with GPE in saturated NaCI solution. TABLE 11. Yields of materials dissolved by formic acid from GPE treated wool fibers.…”

“…Among these are principal component analysis, linear and multiple regression, Mahlanobis distance, and nearest neighbor techniques [ 9,11 ] . The regression methods all assume a linear relationship between input and output.…”

“…Felting potential of treated wool fibers was evaluated using the Aachen felt ball method, as described previously [ 7,11 ] . Amino acid analyses and scanning electron microscope observations were as described in the previous report [6].…”

Improving Functional Characteristics of Wool and Some Synthetic Fibres

“…The first is coating with resins such as polyamide epichlorohydrin or grafting polymers onto wool fibres. The second is morphological modification of the cuticular cells by chemical or physical treatment [7].…”

“…Excellent shrinkage resistance can be imparted to wool by applying GPE in saturated NaCl (sodium chloride) solution in the presence of a reductive agent such as Sodium metabisulfite (Na 2 S 2 O 5 ), while the hydrophobic nature of the surface remains unchanged [7].…”