How to choose nylon fabric acid fixing agent

Why do nylon fabrics need to be treated with color?

Nylon products are mainly dyed with weak acid dyes or neutral dyes. Because dyes contain sulfonic acid, carboxylic acid groups and other anionic polar groups, they usually exist in water-soluble sodium salts in water. , R-COO-, and nylon fiber macromolecules contain a large amount of amide and end amino groups, forming -NH2+-and -NH3+under acidic conditions. Essence

At the same time, the affinity between dyes and fiber macromolecules is also large, and it can also be combined through the force between molecules and Van Dehua power, thereby greatly increasing the adsorption of dyes, increasing the color of the color, reducing the dye dye in dye dyeing in dyeing in dyeing dyeing. The residue in the liquid.

When nylon products are taken, they are often washed, and home washing is generally under alkaline conditions. Dyes will fall off and hydrolyze from the fabric in the alkaline aquatic solution, and in soap or washing Under the action of surface active agents such as powder, far away from the fabric scattered in the water, and may be contaminated on other fabrics, resulting in poor wetness and staining fastness.

Therefore, nylon usually needs to be fixed with a fixing agent after dyeing with weak acidic dyes or neutral dyes to improve its wetness.

The mechanism of acidic color fixing agent

The polymer measuring aromatherapy sulfonic acid contraction is covered on the surface of the fiber. The negative charge of the sulfonyl group on the surface has exclusion to the acidic dyes in the fiber, so that the dye cannot come out. The opportunity of a combination of water molecules decreases, thereby increasing the fastness.

Precautions for the application of acidic fixing agent

1. The color fixing temperature is generally between 70 and 80 degrees. Excessive temperature polymer measures the aromatic sulfonic acid compounds into the fiber and loses the covering effect, so that the negative charge of the sulfonic acid base has decreased to the acid dye in the fiber , Resulting in the decline in the stress.

2. Do not solid the color time for too long. Time excessive high molecular measuring aromatherapy sulfonic acid contraction will spread to the fiber to reduce the covering effect, resulting in a decrease in the accuracy. The acidic fixing agent is generally a polymer and aromatic sulfonic acid or sulfonic acid or The carboxylic acid compound is easy to precipitate under strong acid conditions, that is, precipitation occurs, and solid spots can be produced during fixing.

3. During the color fixation, the acetic acid cannot be diluted with the color fixing agent to avoid precipitation (it is recommended: add an acidic fixing agent first when adding the feeding, operate 5-10min and add ice acetic acid. Add the main cylinder slowly).

4. It is best to use soft water when coloring, so as to avoid precipitation of calcium magnesium ions and fixing agents.

5. Wash the cloth surface before fixing, so as not to produce solid spots when the color is fixed.

6. If the acidic color fixing agent is required to make foaming fastness, it is best to use a acid-tone acidic color fixing agent; the pH value of the general acidic color fixing agent is better to 4.0-4.5.