How is silicone colored? The coloring of silicone products should be handled according to whether the product is dynamic or static. Silica gel coloring methods mainly include surface coloring and mixture coloring. Surface coloring is to spray the colorant on the surface of the silicone product to color the silicone product. This method has a certain effect on static products, but for dynamic products, the colorant is easy to peel off and fade.

Mixing coloring is the main method of coloring silica gel at present, which is divided into solution method and mixing method. Among them, the mixing method has several methods such as dry powder coloring, color paste coloring, pellet coloring and masterbatch coloring.

1. Solution coloring

The method is to dissolve the rubber into a solution of a certain concentration with its good solvent, then add the colorant and the rubber compounding agent except sulfur into the solution, stir and mix evenly, dry at a certain temperature to remove the solvent, and finally put it on the rubber mixing machine. Add sulphur. This coloring method is complicated to operate, the colorant and compounding agent are not uniformly dispersed, there is color difference, the solvent is difficult to recover, and the environment is polluted, so it has been rarely used at present.

2. Coloring by mixing method

This method is the most commonly used method for coloring silicone products at present. The colorant is added directly or mixed with the carrier and then added to the rubber compound, and the rubber is mixed evenly by a rubber mixer to color the rubber. The specific method is as follows:

The dry powder coloring method is to directly add the powder colorant together with the small material into the rubber, and mix it on an open mill. The advantages of this method are simple operation and low cost, but the dust is large during mixing, which pollutes the environment, and is not easy to disperse uniformly, and has color difference. It is less used now. For ease of use, powdered colorants can be made into pre-dispersed colorants together with stearic acid, sulfate, etc., which have been sold in the market.

The method of color paste coloring is to first mix the colorant with the liquid compounding agent (such as plasticizer), grind it with a three-roller machine to make a paste or slurry, and then add it to the rubber in a certain proportion for mixing. This method can avoid dust flying, and is also conducive to the dispersion of colorants in the rubber, and the color is uniform. However, the content of colorant in the color paste is low, the coloring is not high, the transportation volume is large, the loss is large, and the user is inconvenient to use.

There are two main methods for preparing pellet colorant pellets. The first method is the same as other powdery compounding agent granulation methods. First, the powdery colorant is infiltrated with surfactant, and then granulated after being melted with wax or melted with resin; the second method is to use the colorant with After soaking with surfactant, the colorant particles are refined by mechanical force to make a dispersion of a certain concentration, which is then mixed with latex for co-precipitation, and rolled into granules after drying. Among them, the surfactants are mostly anionic and non-ionic, such as fatty acid salts, sulfonates, etc. The latex is usually natural latex.

The granular colorant is easy to use, has good dispersibility, has no dust flying, does not pollute the environment, has bright color, uniform hair color and no color difference, and is a promising coloring method. However, the preparation process of granular colorant is complicated and the cost is high, which limits its wide application.