​What is the main function of the fixing agent?

The dyes used in the textile industry have different drawbacks. For example, reactive dyes lack darker color types and are prone to hydrolysis. This will result in light-colored dyeing and is not resistant to chlorine bleaching. After dyeing, it will fade when washed. Its wet fastness is very poor, so we need to use fixing agent for fixing.

This passage is going to talk about the following questions of fixing agent:

(1) What is fixing agent?

(2) Introduction to the principle of fixing agent

(3) What is the preparation method and composition of the color fastness agent?

(1) What is fixing agent?

There are many types of fixing agents. The structure of the fixing agent is short but practical. Fixing agent is mainly used as a color fastness agent for printing or dyeing acid dyes. When used to process cotton, silk, rayon, it will enhance the fastness to washing and soap washing. In the sizing process of yarn-dyed fabrics, the use of this product can prevent penetration and color sticking. Color fastness agents are also used for the color fastness of lakes and paper dyes. However, it cannot be used to treat intolerant sulfur black dyes and resin finishing agents.

(2) Introduction to the principle of fixing agent

The molecular cationic group in the fixing agent forms an electrostatic bond with the anionic group in the dye, and the dye and the fixing agent will stick to the fiber. This will reduce its water solubility and improve the soapability and fastness of dyed fabrics and white cloth. The stronger the cationic fixative, the better the fastness of soaping and white cloth.

Through the cross connection between the reactive groups of the fixing agent molecules, the reactive groups on the dye molecules and the hydroxyl groups of the fiber molecules, the water solubility of the dye can be reduced, the soap fastness of the fabric, and the color and wetness of the white cloth can be improved. Fastness to ironing. Wet ironing fastness refers to the fastness of the bond between the activated dye and the unfixed dye being broken and transferred to the fabric during ironing of a wet cloth. In order to improve the wet ironing fastness, the method of using a cross-linking agent is effective. Through cross-linking, the bond breaking dye will no longer be transferred from the dyed fabric to the ironing cloth. The introduction of reactive groups into the fixing agent can improve the wet ironing fastness. Due to the insufficient content of reactive groups, the wet ironing fastness effect is not as good as the crosslinking agent. Fixing agent on the market. If the fixing agent is a high polymer with the same number of reactive groups, its performance in improving wet ironing fastness is generally worse than that of the low molecular weight fixing agent.

(3) What is the preparation method and composition of the color fastness agent?

Color fastness agents are also called whiteness and color fastness agents. Oatmeal is a water-soluble early shrinking agent of dicyandiamide formaldehyde resin. Fastness agents can be divided into powder and clear liquid. The appearance of the dry fastness agent for sharpness is white. It can be dissolved in water to complete. Liquid sensitizer Y is a colorless and transparent viscous liquid. The solid content is 48%~55%. It has excellent fluidity at 20°C. Easily soluble in water, 2% acetic acid and formic acid solution. It can be used with nonionic, positive ion surfactants or positive ion synthetic resin shrinking agents, but it cannot be used with negative ion surfactants. It will form precipitates combined with strong acids, strong alkaline tannins, sodium formaldehyde sulfoxylate, sulfates, and hydroquinone.