Colouring Classification of Silicone rubber Products

In addition to superior product performance, silica gel products also have a unique advantage that is the color change. A good product is first from outside to inside. Many people want to see the actual use effect of the product, but also have certain standards for the appearance. Most consumers are interested in the appearance of the product, so the appearance of silica gel products is naturally very important.

Solution Coloring

The method is to dissolve silicone rubber into a certain concentration solution with its good solvent, then add colorant and silicone rubber compound except sulfur yellow into the solution, stir and mix evenly, dry the solvent at a certain temperature, and finally add sulfur yellow to the rubber mixer. The operation is complex, the dispersion is not uniform, the color difference is colored, the solvent is difficult to recover, the environment is polluted and less used.

Mixing coloring

This method is currently the most commonly used method for coloring silicone rubber products. It is to add the colorant directly or mix with the carrier first and then with the rubber compound. The silicone rubber is colored by mixing evenly through the rubber mixer. It can be divided into the following methods.

Dry pink colouring

The powder colorant is directly added to the silicone rubber with the small material and mixed in the smelter. The advantages are simple operation and low cost, but the mixing dust is large, polluting the environment, and is not easy to disperse uniformly, with color difference. If the particles are too hard and coarse, it will cause quality problems such as color spots, stripes or chromatographic cross-contamination, which are seldom used.

Colouring paste

Firstly, the colorant is mixed with liquid compounding agent (such as plasticizer), then the paste or paste is made by grinding with a three-roll mill, and then the paste is mixed into silicone rubber in a certain proportion. This method can avoid dust flying, and is conducive to the dispersal of colorants in rubber, with uniform color. But the colorant content in the paste is low, the coloring is not high, the transportation is large, the loss is large, and the user is inconvenient to use.

Granular colouring

There are two main preparation methods of colorant granules. The first method is the same as other granulation methods of powdery complexes: first, the powdery colorant is soaked with surfactant, then extruded by wax melting or melting with resin, and then granulated; the second method is that the colorant is soaked with surfactant, then refined by mechanical force to form a certain concentration of dispersions, then mixed with latex and co-precipitated, dried and then rolled to granulate. 。 Granular colorants are easy to use, good dispersibility, no dust flying, no pollution to the environment, bright color, uniform hair color, no color difference. It is a promising coloring method.  However, the preparation process of granular colorant is complex and high cost, which limits its wide application.

Attention Problems in Processing Colored Silica Gel Products

Whether the ingredients and materials of colour gum meet the standards, many products have color differences and colour spots in raw materials, miscellaneous and so on, mainly because the colour gum has not been properly blended! 

In the mixing process, the mixing time of colour glue and raw material is too short, resulting in uneven colour of products and large local color gradient.

In the production process of products, the placement of raw materials leads to material marks. This phenomenon is often caused by the backlog of product materials in a part of the die, which can disperse the raw materials to swing!

In color matching, the ratio of raw materials to color glue is not accurate. Generally speaking, the ratio of color glue to glue is 1:10. Therefore, it is necessary to control the weight of color glue and glue as accurately as possible in order to prevent color change.