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How does nylon dyeing prevent defects(3)?

Date:Mar 25, 2021

1. The sample must be strict and accurate in color

(1) The color and color matching environment design of the laboratory should be able to choose a series of colors such as black, white and gray, so as to prevent the "after-image" caused by the environmental color on the physiology of the eyes from affecting the color. The lighting of the color environment must be sufficient to prevent the hue change caused by the light source during the color matching. A fixed light source with "conditions" should be used, or a light box that meets international standards should be used. If the light source is more likely to change, such as the laboratory’s open color environment, the light source outside the window will be different at different times-the light source changes (for example, the light source is different in the morning and afternoon, the sky is cloudy and sunny) The light source is different), which affects the color matching power.

(2) Before making the approved sample, we should probably figure out the various needs of the customer, such as the original color and light tendency, whether there is special cleaning, whether the dye for fiber dyeing is designated, etc.

(3) The water used for making small samples should be the same as the production of large samples, and the water quality and pH value should be tested daily, and adjusted to technical requirements to prevent the occurrence of color and light differences.

(4) The dyeing function of nylon fiber also changes with its heat history before dyeing. Different heat setting conditions will result in different fabric color absorption rates, which will then result in the color difference between batches of fabric. The technical control of the pre-treatment of nylon fabrics also has a great impact on the dyeing effect, so the size and sample arrangement standards should be the same, and the technical conditions of the semi-products before dyeing should be the same.

(5) For the small sample, the dyestuffs with the same origin, the same factory, the same product name, and the same batch number should be selected as the large sample. The compatibility value of the dyes selected during color matching must be basically the same, so as to ensure the proportional relationship of the dyes in the dyeing solution during the dyeing process, which is conducive to the stability and reproducibility of the dyeing shade. When matching colors, the main color dye should be fixed, and the dye for adjusting the shade should be changed so that the large and small samples have the same shade. Dyes that simply cause discoloration during the dyeing process are not used.

2. Standardized color matching operation in laboratory

(1) Generally speaking, the closer to the color of the gray series, the more difficult it is to distinguish its gray saturation, because the absorption hue it contains is more complicated, and three kinds of dyes are often required to mix, so the hue of the gray series can only be matched. Choose the color tendency based on the feeling of yellow, red, and blue. The more the color is felt, the more important it is to distinguish the hue from the freshness and purity of the color. Therefore, the correct judgment must be made when matching colors and the correct dyes should be selected.

(2) Pay attention to the changes of the survey sample and the light shining point of view when matching colors, so as to keep the same.

(3) Grasp the drying degree of the sample cloth after dyeing. Excessive drying will result in an irreversible reddish tint; failure of drying will affect the fullness of the color sample. Both conditions will result in shade errors.

(4) When imitating color, attention should be paid to the classification and color separation system, and the samples should be kept, and the materials should be piled up to establish a color sample library (the corresponding practical samples are very good).

 3. Strictly control the commonality of large and small technologies

(1) The pH value of the proofing dye bath and the heating technology should be as common as possible with large-scale production. Because of the interspersed use of water quality and direct steam or direct steam in the production of large samples, the boiler steam is often brought into alkalinity and the pH of the dye bath is high. The use of buffers or equipment pH online monitors can solve this problem.

(2) Keep the heat preservation of the small sample dyeing at the same time as the large sample to avoid the formation of color difference due to poor dye penetration.

(3) Since color fixation also affects the color light, the color light must be adjusted after the sample is fixed before it can enter the technical development of large-scale production. There are many factors that affect the quality of nylon dyeing products, including equipment, technology, dyeing materials, color difference of size and sample, and operation. Production practice has proved that if the above-mentioned links are well grasped, the accuracy and stability of nylon dyeing can be improved, and the one-time success rate of sample lofting can reach more than 90%.