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The composition of the printing sample paste of weak acid dyes, neutral dyes and direct dyes used for silk knitwear is not complex, and it is mainly composed of dyes, urea, ammonium sulfate, raw paste, etc.

The selection of dyes should be based on the color brilliance and color fastness reaching the standard, and also consider the solubility and color giving amount of dyes, and select dyes with similar blood lines for color matching. When using, pay attention to the amount of various dyes in the color paste to ensure the wet treatment fastness of knitted fabrics, so as to prevent white ground contamination and color fading.

Urea is a hygroscopic agent and cosolvent, which has the effects of hygroscopic, solubilizing and swelling. When dissolving dyes, for example, the cosolvent gulixin a can be added to help dissolve insoluble dyes.

Ammonium sulfate is an acid releasing agent, which can regulate the pH value of printing sample pulp. In the process of steaming with heat, the release of acid agent will promote the dye to dye to the fiber.

The printing of silk knitwear requires clear generalization, uniform color on the surface, bright color and white ground. To achieve the above requirements, the selection of printing paste has important practical significance. Paste has excellent compatibility with dyes and chemicals, and has adhesion, good scraping and printing, excellent permeability and easy washing. Etherified seed gum paste is selected. Now, in the actual production of printing enterprises, starch paste has rich origins, low prices, and no

It is directly related to the dyeing depth and the amount of dye. When weak acid dyes are used for nylon dyeing, the combination of dyes and fibers, hydrogen bonds and van der Waals force play an important role. Production practice has proved that weak acid dyes are used in nylon dyeing, which are not constrained by the dyeing plumpness value, and the color is deep. Therefore, weak acid dyes are selected for the printing and dyeing processing of nylon products.

Neutral dyes are dyes that are suitable for dyeing in neutral or weak acid dye baths by complexing dye molecules with metal chromium (or cobalt) in a ratio of 2:1. They are collectively referred to as neutral complex dyes. Domestic products are called neutral dyes for short. One of the primary advantages of this dye is that it does not need to be treated with chromium medium after dyeing.

The dyeing process of neutral dyes is very similar to that of weak acid dyes. The metal complex ion with negative charge can generate charge attraction with the ionized amino group on the fiber. The pH value of the dyeing bath directly affects the dyeing rate. In order to prevent dyeing too fast and uneven formation, the pH value of the dyeing bath is controlled at neutral or near neutral. The pH value can be adjusted to 6 ~ 7 with ammonium salt, and then with the decomposition of ammonium salt, the acidity is enhanced to enhance the dyeing fiber. In addition, hydrogen bonds and van der Waals force also play an outstanding role in dyeing with neutral dyes.

Direct dyes are mainly used in the absence of color matching chromatography to make up for color matching needs.

Considering the adaptability of the above dyes to fibers, dyeing depth, dyeing fastness, operation feasibility, complete color matching chromatography and other factors, weak acid dyes are mainly used for printing silk knitwear and nylon knitwear. Neutral dyes and direct dyes with high dye uptake for the above fibers can be used when printing medium and dark colors, so as to meet the needs of color matching and color matching.

Article source: Jiangmen printing pastehttp://www.caiyicp.cn/