In-depth Analysis Of The New Revolutionary Process Of Manufacturing Color Rubber Products Technology

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, add sulfur to the rubber mixer. This coloring method is complicated to operate, the colorant and compounding agent are not uniformly dispersed, there will be color difference, the solvent is difficult to recycle and pollutes the environment, so it has been rarely used at present.

Mixing coloring

This method is the most commonly used method for coloring rubber products at present. The colorant is directly added 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 method of dry powder coloring is to add the powder colorant directly together with the 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. If the pellet are too hard and too thick, it will also cause quality problems such as color spots, streaks or mutual contamination of the chromatogram, so it is rarely used at present. For ease of use, powdery colorants can be made into pre-dispersed colorants together with stearic acid, sulfate, etc., which are already available in the market.

The method of paste coloring is to mix the colorant with the liquid compounding agent (such as plasticizer), then 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.

Pellets coloring

There are two main methods for preparing colorant pellets. The first method is the same as the powder compounding granulation method. First, infiltrate the powdery colorant with surfactant, then melt it with wax or extrude it with resin, and then granulate it; The second method is to infiltrate the colorant with a surfactant, and then refine the colorant particles by mechanical force to make a dispersion of a certain concentration,  then mix it with the latex for co-precipitation, and extrude it to make 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 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.

 This method of masterbatch coloring is to mix colorants, part of plasticizers and other rubber compounding agents with raw rubber through an open mill to make a colorant masterbatch with a concentration of about 50%, and then add it in proportion to the colorant masterbatch. This method is more effective for colorants with fine particles and difficult to disperse, with uniform color development and no color difference. When compounding, pay attention to the concentration of colorants in the masterbatch and deduct the amount of other compounding agents in the masterbatch.