Test standards:

The fabric's color fastness to light and perspiration is tested using GB/T 14576-2009 "Textiles Color Fastness Test - Light and Perspiration Composite Color Fastness"; the pH value of the fabric is tested using GB/T 7573-2009 "Textiles Water Extract pH" Determination of value test.

Test results:

1. The effect of dye concentration on the light fastness and light perspiration color fastness of fabrics. Six reactive dyes of different colors were selected and dyed using the two-bath pad dyeing method. The dyed fabrics were tested and rated according to national standards. The results were The results are shown in Table 1.

It can be analyzed from Table 1 that for reactive dyes of different colors, as the dyeing concentration increases, the color fastness to light and perspiration of the fabric obtained will increase to a certain extent. As can be seen from Table 1, the test results of different concentrations of two varieties of yellow reactive dyes, Golden R-4RFN and Golden RES, show that their light and sweat resistance can reach level 4 or above, and they have good light and sweat resistance. Reactive Red For the two varieties, as the dyeing concentration decreases, their light resistance decreases to a certain extent. Especially when the dyeing concentration decreases to 0.3g/L, the resistance to acid sweat and alkali sweat decreases significantly. The test results of blue reactive dyes show that the light fastness and light perspiration color fastness of Emerald Blue G cannot meet the requirements of daily use. Compared with the original sample, the tested sample has obvious fading, which is in line with the consumer concerns. Complaints were relatively consistent. In addition, reactive dyes have certain sensitivity to the components of sweat, and alkali sweat has a greater impact on them than acid sweat. It can also be seen from Table 1 that the color fastness to light and perspiration of reactive dyes is not only related to the concentration of dyeing, but also to the type of natural color of the dye. The structure of different natural colors of dyes causes differences in color fastness to light and perspiration.

2.The influence of pH value on the color fastness of fabrics to light and perspiration. The acidity and alkalinity of the fabric surface has a great influence on the performance of the fabric. Since pure cotton fabrics generally need to go through mercerization and washing procedures during the post-finishing process, the pH of the fabric surface changes greatly. The pH of the fabric affects its light-sweat resistance to a certain extent. In this experiment, the pH value of the fabric surface was adjusted by padding with sodium carbonate solution and acetic acid solution to test the effect of pH value on the color fastness of the fabric to light-sweat. The test results are shown in Table 2.

By changing the pH of the fabric surface and re-testing the color fastness to light and perspiration of the fabric according to the national standard method, it was found that the pH has a certain influence on the light and perspiration test of the fabric. When the fabric surface is neutral, its light and sweat resistance is the best. As the pH of the fabric surface is adjusted, its light and sweat color fastness will decrease to a certain extent. When the surface of the fabric is adjusted to be acidic, its color fastness to acid perspiration decreases significantly; when the surface of the fabric is adjusted to be alkaline, its color fastness to alkali perspiration decreases significantly. The reason for this pattern may be that the acid and alkali substances on the surface of the fabric enhance or weaken the effect of acid and alkali on the fabric during the test, thus leading to changes in the light and sweat resistance of the fabric.

3.The impact of color matching on the color fastness of fabrics to light and sweat. In the actual dyeing process, it is usually necessary to mix several basic colors to match the required color. However, due to the ratio of different dyes that have better light-sweat resistance, the dyes golden R-4RFN and red R-2BF, and the golden RES and red RES are mixed and dyed, the color fastness of the fabric to light and sweat is better; When the dye is added with blue C-R and turquoise blue G, which have relatively poor light fastness to light and perspiration, the fabric's light and perspiration color fastness will show more obvious discoloration and fading. Therefore, when multiple colors are matched and then dyed, even if there are multiple dyes with good light fastness to perspiration, the light fastness to perspiration of the fabric is determined by the dye with the worst performance.

 

Test Conclusions:

(1) The color fastness to light and perspiration of reactive dyes is not only related to the concentration of dyeing, but also to the type of natural color of the dye. The structure of different natural colors of dyes causes differences in color fastness to light and perspiration.

(2) When the fabric surface is neutral, its light and sweat resistance is the best. As the pH of the fabric surface is adjusted, its light and sweat color fastness will decrease to a certain extent.

(3) A variety of colors are dyed after matching. The fabrics have different light-perspiration and color-fastness properties. There will be differences in the actual application process, which will have a certain impact on the light-perspiration color fastness of the fabrics. By mixing several dyes and then dyeing, the light and perspiration color fastness of the tested fabrics is shown in Table 3.

It can be seen from the test results in Table 3 that there are large differences in the light and sweat resistance test results of fabrics dyed under different ratios of several reactive dyes. The degree is determined by the worst performing dye.

 

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