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1Various gray fabrics
The gray fabric should be scouring or degreasing before dyeing, and the small sample may not undergo pre-treatment, or the small sample processing method may be different from the large sample production in the workshop. The moisture content of gray cloth is different, and the different moisture content of the sample has a greater impact. Due to the different moisture content, the weighing volume is also different. For this reason, it is required that the gray fabric produced as a sample must be completely consistent with the gray fabric produced in the workshop.
2 Differences in dyes
Although the dyes used in the sample are different from those in the large The dyes used in the samples are of the same variety and strength, but the batch numbers are different or the sample is not weighed accurately enough, which may cause differences between the small samples and the large samples. It is also possible that the dyes used for large-scale production have agglomerated and become damp, and some dyes are unstable, resulting in a decrease in strength.
3 The pH value of the dye bath is different
Generally, the pH value of the dye bath is more accurate for small samples, but the pH value is unstable or no acid-base buffer is added during the production of large samples. Due to the alkalinity of the steam during dyeing, the pH value rises during the production of large samples, and some disperse dyes For example, those containing ester groups, amido groups, cyano groups, etc. will be hydrolyzed under high temperature alkaline conditions. There are also some dyes whose carboxyl groups can be ionized under alkaline conditions, increasing their water solubility and reducing their dye uptake rate. When the pH value of most disperse dyes is 5.5-6, the color light is normal and stable, and the dye uptake rate is also high. But when the pH value increases, the color light changes. For example, when the pH value of dyes such as dispersed black S-2BL, dispersed dark blue HGL, and dispersed gray M is higher than 7, the color and light will change significantly. Sometimes the gray fabric is not fully washed after pre-treatment and becomes alkaline. The pH value of the dye bath increases during dyeing, which affects the shade.
In addition, is the pre-processing of the gray fabric pre-shaped? If the large sample gray fabric has been pre-shaped, the small sample gray fabric has not been pre-shaped, or even the large sample and the small sample have been pre-shaped, and different setting temperatures can also cause different color absorption.
4 The influence of liquor ratio
During the sample test, the liquor ratio Generally larger (1:25-40), while the large sample bath ratio varies according to different equipment, generally 1:8-15. Some disperse dyes have little dependence on liquor ratio, and some have great dependence. This causes color difference due to the difference in liquor ratio between the small sample and the large sample.
5 The impact of post-processing
Post-processing affects color difference one of the reasons. Especially for medium and dark colors, if reduction cleaning is not performed, in addition to floating colors, it can also affect the color light and produce a certain color difference. Therefore, the restoration cleaning must be consistent with the small sample and the large sample.
6 The influence of heat setting
Disperse dyes can be divided into high temperature type, medium temperature type and low temperature type. When color matching, you should choose the same type of dye. In case of high-temperature type and low-temperature type color matching, you should consider that the setting temperature should not be too high when heat setting to avoid excessive temperature, which will cause certain dyes to sublimate and affect the color light, resulting in color difference. The requirements for finalizing conditions for small samples and large samples are basically the same. Because whether the pre-treatment is set and the setting conditions (temperature) have a great impact on the color absorption of polyester (the greater the degree of setting, the lower the dyeability), so the fabric used for the small sample must be consistent with the large sample (that is, before production Use workshop semi-finished product samples). </p
