Adjusting the Black Suede Textile Dyeing Addition Method
With the liberation of productivity, the demand for suede leather fabric such as suede cloth fabric has grown substantially. Black suede textile accounts for a large proportion of our country's tanning enterprises. But at present, there are few kinds of dyes for black dyeing, the purity is not high, and the secondary color is heavier. The black dyeing of suede fabrics has always been a headache. Either it cannot be dyed black, and the amount of dyes increases; To dye black leather, especially black suede leather fabrics, the following key steps must be followed.
(1) Pre-staining
Before chrome retanning, add a little black dye for pre-dyeing. The dosage is generally 0.5% of the weight of the leather. At this time, the wet blue leather has a strong positive charge, and the anionic dye is quickly combined on the surface of the leather. less, it will not have a great impact on the leather surface. Then, chrome tanning (or multi-metal tanning agent retaining) is carried out, and the positive electricity is strengthened again so that the dyes are further fixed. At this time, the fixed dyes are very strong and difficult to be washed in the subsequent neutralization and retaining. Detach, and lay the foundation for the final increase in the concentration of color on the surface of the suede fabric.
(2) First through dyeing and then surface dyeing
This method is often used when both dye penetration and black purity and fullness are required. The dye was added in two portions. The main purpose of the first dyeing is to dye through, so acid dyes with small molecules and strong permeability should be used. Before adding dyes, 0.5% to 1.0% ammonia water can be added to increase the pH value to promote dye penetration. After dyeing, acid was added to fix the color, and the liquid was changed for the second dyeing. The main purpose of the second dyeing is to make the surface color thick and the blackness pure. It should be mainly direct dyes with strong surface coloring ability. At the end of dyeing, add acid to fix the color and adjust the pH value to 3.5 ~ 3.8.
(3) "sandwich" staining method
That is, a cationic material (such as chromium powder, cationic resin tanning agent, etc.) is added in the middle of the two anionic dyestuffs. Such as dyeing - oiling - chrome tanning - dyeing. Compared with chrome tanning-dyeing-refueling, its advantages are: first, there is no chrome retanning before the first dyeing, the positivity of the leather is low, and the dyes are easy to penetrate; which increases the positivity of the leather, which does not only fix the dyes and oils added first but also facilitates the dyeing of the dyes added later; third, because the cationic auxiliaries are added in the middle of two dyeings, and added after the dyeing is completed In comparison, it is less likely to cause the problem of uneven coloring.
(4) Top dyeing
The principle of the top dyeing method is the same as that of the "sandwich" dyeing method, which is to increase the positivity of the leather before the final dyeing. The basic method of top dyeing is, dyeing oil - fixing color-changing water and adding dye top dyeing - formic acid fixing. After changing the water, add a small amount of formic acid or fixing agent for 10 minutes, and then add dye top dyeing. The difference between the top dyeing method and the dye addition method is that the second dyeing of the former is supplementary dyeing, while the second dyeing of the latter is a step of the main dyeing.
(5) Overdyeing
That is to say, the wet leather dyed with anionic dyes is then color-coded with basic dyes (cationic dyes). The chrome-tanned leather is neutralized, retanned with anionic tanning agents (tannin extract, synthetic tanning agent, polymer tanning agent, etc.), and dyed with anionic dyes and oil so that the surface anion is significantly enhanced. The leather fiber and the dye can show a strong affinity, which is not only conducive to the dyeing of cationic dyes, but also to the fixation of the anionic dyes and oils added first, and the thick tones are thick. However, due to the poor fastness of basic dyes, it is generally only used for over-dyeing of black suede, and the dosage should not be too large, and the general dosage is about 0.5%.
SUZHOU KRS is an industrial and trade integrated printed fabric manufacturer, which started in 2012. SUZHOU KRS has accumulated rich production experience and technology in this field. The suede knitted fabric uses imported tercio high-speed warp knitting machine weaving, a mature product production system, the most competitive product quality, and low price. Widely used in shoe material, high-end luxury car interiors, fashion fabrics, and so on. The suede knitted fabric is one of our products, more details are as follow:
Brand
KRS
Model
DT-SK-R005
Minimum
120
Standard
105/75/70
Unit
YARDS
Pack
ROLLS
If you are interested in our products, please contact us as soon as possible.