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Analysis on the Application of Experimental Standards for Color Fastness to Water on Printed Fabrics
1. Introduction The color fastness to water is an important test item for textiles, and it is one of the assessment indexes stipulated in the mandatory national standard GB18401 'National Basic Safety Technical Specifications for Textile Products'. At present, the textile color fastness standard used in my country is GB/T57131997. The color fastness test of this standard is equivalent to the international standard ISO105-E01:1994. The color fastness to water is directly related to the performance of the textile. However, there is a special situation in the actual test, that is, some printed fabrics will have obvious visible marks after being soaked in water and dried. However, according to the current standards, the water resistance The fastness was tested, but it was found that the fastness level of the test was very high, so there was a phenomenon that the test results could not reflect the actual use performance. 2. Test principle The test principle of color fastness to water in the standard GB/T57131997 is to stitch textiles and lining fabrics together, soak in test water, squeeze out the moisture, and place them in a perspiration fastness tester for pressure treatment; Put it in an oven at 37°C for 4h and take it out, then hang it in the air not exceeding 60°C to dry; after drying, use the discoloration and staining gray card to evaluate the discoloration of the fabric and the staining level of the lining. 3. Problems in the application of standards 1. Standard test results The problem samples tested in this test are reactive dye printing fabrics with white ground and dark blue colors. Tested according to GB/T57131997, its discoloration grade and staining grade are both 4 to 5, which has reached the most stringent requirements of GB18401 for Class A 3 to 4, and the detection level is very high. 2. Actual use condition According to the standard test results, it is possible to issue a qualified report of color fastness to water. However, the clothing made of this fabric has obvious problems in actual use, and marks appear after soaking and drying. As shown in Figure 1. 3. Analysis of standard problems ①. The production of imprints. After printing, the fabric may still have unfixed dyes or hydrolyzed dyes. Reactive dyes are water-based. They will migrate with the movement of water during the drying process after washing. Dye accumulation is formed on the surface, and imprints are produced at the dye accumulation. ② Reasons for impressions but qualified test 1) In the test of standard GB/T5713, it has been treated in an oven at 37°C for 4 hours before drying, and the moisture is very small before drying; but during self-washing and drying, the Relatively more water, migration is more likely to occur. 2) GB/T5713 stipulates that when the sample is dried in the air, once it is found that there is an air-dried sample, it must be discarded and redone. This requirement is because when the sample with air-drying phenomenon is dried, the water disperses too quickly, and the dye on it will be unevenly distributed due to migration, so that the final result cannot be accurately judged. When washing and drying by oneself, air drying is not avoided. 3) After washing and drying the sample, there will be imprints. The main reason is that the printing is white, and a little staining is very obvious. However, no staining of the lining cotton cloth was found in the test, because the standard GB/T5713 test fabric used was small, with a size of only 4cm10cm, and the dye concentration accumulated by migration was not enough to produce obvious marks. In fact, it can be seen from Figure 1 that only one impression can be found on a larger area. IV. Recommendations 1. In terms of standards, printed or white printed fabrics with light-colored backgrounds, and even light-colored dyed fabrics, may have similar confusion, that is, the color fastness to water is fully qualified through the standard test, but may be larger samples When immersed in water to dry, imprints will appear due to the accumulation of dye migration. Except for GB/T5713 and the equivalent ISO105-E01:1994, the current textile color fastness standards include the American Association of Dyeing and Chemists standard AATCC107 and the Japanese Industrial Standard JISL0846. These standards are used in constant temperature time, paste There are certain differences in the selection of lining fabrics and oven temperature. Some researchers have compared a large number of sample tests and found that the test results of different water fastness standards for the same fabric have relatively small differences in discoloration and large differences in staining[1], but These standard detection principles and procedures are basically the same, and none of them can reflect the actual performance in such special situations. This kind of situation is that the dark part of itself is contaminated with the light part, which can be self-contaminated, but its color fastness is not bad enough to contaminate the lining. Therefore, it is necessary to establish an independent detection method for this type of product. There are two aspects in the detection method that need to be studied. One is the selection of sample size, because the effect of dye accumulation in this case requires sufficient area for the sample to appear; the second is the establishment of the rating method because of uneven discoloration. It is its characteristic that requires a larger area of u200bu200boverall evaluation, which requires the formulation of corresponding sample cards or descriptive regulations. 2. In terms of production, this sample was washed with water and found obvious imprints, which is undoubtedly a problem with the fastness, but it is qualified by the current standard.
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