Study on the printing and dyeing process of crepe

Study on the printing and dyeing process of crepe

Finishing is the production experience of dyeing technology and titanium dioxide matting on the cotton fabric.

Printing

Although the printed products can be used for finishing, it is better to use a discharge printing process to achieve a satisfactory feeling. Because the process can not only solve the problem that the flat screen can not open the screen directly, but also solve the direct printing of the mosaic, especially the problem that the thin stem cannot overlap with the ground color. Moreover, it can also print extremely fine patterns and delicate and even, shallow and natural transitions.

1. Requirements and selection of ground color dyes

Discharge printing is accomplished by the reduction of the reducing agent to destroy the chromophore in the ground dye. There are many varieties of dyeing dyes applied to viscose fibers, such as direct, active and insoluble azo dyes. However, it is necessary to require the azo group to be sensitive to the reducing agent, and the amino compound having a split has a small affinity for the fiber. When the ground color dye is selected, the method for judging whether the cracked amino group remains on the fiber is as follows: the white washed sample after washing with water, treated in a 5 g/L NaNO 2 solution at room temperature for 3 minutes, and then treated with 10 ml/L hydrochloric acid for 5 minutes. Then, a 10% varvin solution was added to the whitened portion to observe the color. If it is not light reddish brown, it means that the whitening effect is good, otherwise, the whitening effect is not good.

2. Selection of commonly used soil dyes and their additives

The vat dye used for printing requires fine particles, sufficient reduction, fast reaction rate and high fixation rate. Experimentally verified, soil forest 5GK yellow, GOK yellow, R peach red, GGN red, red green lotus RH, 2R green lotus, bromine blue 2B, green FFB, green 4G, brown RRD, red R, orange RF and black CL Suitable for discharge printing. However, RRD brown, 2B blue, FFB green, RH lotus, etc., which have coarser particles, must be sufficiently ground during application.

Carved white powder is the most important printing aid, and it has the strongest reducing ability when steaming at 100 °C. When steaming, [H] is released, which destroys the chromophoric group of the ground dye to achieve the purpose of removing the base color, and at the same time, the vat dye in the printing and dyeing is reduced to a leuco body to be dissolved and dyed onto the fiber. The factors determining the amount of white powder used are: the degree of difficulty in dyeing the dyed ground color, the depth of the ground color, the amount of dye, and the difficulty of reducing the dye. The amount of carved white powder is not enough. First, it is incompletely carved, and it also produces deep and shallow disease. If the dosage is too much, it will cause oozing and coloring. Therefore, the correct and reasonable amount is the key to the success of the discharge printing. The carved white powder is relatively stable at room temperature, thus bringing convenience to the preparation of the color paste.

When the temperature rises to 70 ° C, the white powder gradually decomposes with the increase of temperature, and the decomposition rate increases at about 80 °C.

The alkali agent in the discharge printing mainly uses soda ash. The color paste made of caustic soda has poor stability, and the carved white powder decomposes quickly, and is basically not used.