1, leather commonly used dyes:

Commonly used dyes for leather are generally divided into water-soluble dyes (such as dyes used in chrome tanned leather dyeing) and water insoluble dyes two categories, commonly used is water-soluble dyes, the main cationic acid dyes, direct dyes, reactive dyes, cationic alkaline dyes, amphoteric metal complex dyes and sulfonated alkaline dyes, of which acid dyes account for about 70%.

2, leather special dye:

Because the dyes currently used in the leather industry are mostly dyes borrowed from the textile industry, but because the leather fiber is different from the general fabric fibers or other protein fibers, it has a strong charge and a great difference in the affinity for dyes, and the leather has a certain thickness, and the molecular size of various dyes is different, so that the dyeing has different permeability. All of these bring certain difficulties to the color matching and dye mixing when dyeing leather, resulting in uneven dyeing or inaccurate tones. It is often difficult to achieve satisfactory results, and the color fastness is not satisfactory. This has promoted the development and development of leather special dyes, and a large number of leather special dyes have appeared.

3. Dyeing process:

From a structural point of view, there are a wide variety of special leather dyes, almost including all kinds of dyes, of which azo and metal complex dyes are mainly, especially the latter in the application of leather faster development. When dyeing, several dyes of the same ion type are mixed according to color and dyeing requirements. Chrome-tanned leather dyeing is a complex physical and chemical process, which can be divided into three stages, including adsorption, penetration and fixation. Among them, the adsorption rate is very fast, and the dynamic equilibrium is quickly reached, while the penetration is slow, and fixation has a greater influence on the penetration and dyeing effect. Therefore, in the dyeing process of chrome tanned leather, the dye penetrates into the leather and the fiber, and the combination of dye and leather fiber is the two main aspects that determine the dyeing effect. In the general dyeing process, the initial control is based on penetration, and the conditions are changed to make it mainly combined after penetration meets the requirements.

The dyeing of tie-dye printing is mainly surface dyeing, which needs to choose dyes with surface coloring, strong hiding power and fast dyeing speed. The length of dyeing time, the amount of dye, and the temperature are also determined according to different patterns and dyes through multiple tests. When dyeing in the groove, it is necessary to prevent detaching. When impregnating the vessel, turn it regularly. Generally, it can be completed in (30 ~ 60) minutes. After dyeing, formic acid or cationic additives can be used to fix the color, and then the second fat.