Principle of pretreatment solution for pigment printing.

Nowadays, paint digital printing is the most environmentally friendly printing process. No waste water is produced during the printing process. The amount of soot during the drying process is only about 25% of the heat transfer fixation.

Paint digital printing has good color effect in order to print. Usually need to choose the digital printing pretreatment liquid corresponding to the fabric when the paint ink is selected, and the fabric is pretreated. Why is this?

  

The reason is because:

Fabrics are usually negatively charged in aqueous solutions. Most paint inks are prepared with anionic resins (auxiliary/dispersant), and paint inks are also negatively charged. There is a phenomenon when the ink is printed on the fabric, and there is a certain repulsive force between the fabric and the ink. This causes the ink printed on the fabric to easily diffuse and penetrate to the opposite side of the fabric. Finally, the printing pattern is not clear and the color is not bright enough.

 

The light-colored cotton and its blended fabric are processed by the pre-treatment liquid. It can obviously improve the color, vividness and fastness of digital paint printing, and achieve better printing effect. How does the pre-printing liquid improve the printing effect? Let us first look at the composition of the paint and pretreatment liquid.

 

Paint ink composition: It is composed of anionic PU resin, paint color paste, surfactant, dispersant, viscosity regulator, and deionized water. All are anionic or nonionic.

 

Pre-treatment liquid composition: It is composed of cationic modifier, inorganic salt filler, wetting agent, PH value regulator, and deionized water. All are cationic or non-ionic.

 

It can be seen from the composition of the ink and treatment liquid above. One is a cation and the other is an anion. The pre-treatment liquid chemically reacts with the hydroxyl groups on the fiber to form a covalent bond to make the fiber positively charged. Or make the fiber positive by physical adsorption. The fastness of paint ink mainly depends on PU resin. When the anionic resin encounters the cationic additives, it immediately solidifies into a film, which is fixed on the surface of the cloth to obtain clearer and brighter colors.

 

There are many varieties of pretreatment liquids on the market. The quality is uneven and the price is also different. If you want to choose a good pre-treatment, pay attention to the following issues.

1. The coloring rate is not high. Mainly because the content of cations is low.

2. The fabric is yellowing, and the white cloth with cationic treatment is used, and the yellowing is serious after high temperature baking. The cationic component of the treatment liquid is not resistant to high temperatures.

3. The fabric is hard, and the white cloth with the treatment liquid has a hard hand feeling. The cationic molecular chain of the treatment solution is too long.

4. The color fastness is not good. This is related to the formulation of the treatment liquid.

A good quality pre-treatment can add luster to the printing and enhance the value of the fabric.

Jervay digital printing pretreatment liquid series have been tested in the market and the formula has been mature.