When Is The Best Dyeing Effect for TPE\TPR? How To Ensure Uniform Dyeing

1. Two Dyeing Times

There are two types of dyeing for TPE\TPR, depending on the specific production process and requirements:

1. Dyeing before granulation

Mix the pigment or masterbatch with raw materials such as SEBS and SBS evenly, and then granulate. This method is suitable for mass production and can ensure the uniform distribution of pigments in TPE\TPR particles, so as to obtain consistent color effects in the subsequent injection molding process.

2. Dyeing before molding

This is achieved by adding pigments or masterbatches into the hopper of the molding machine, where they will mix with the TPE\TPR melt. However, this method may not be as uniform as dyeing before granulation, because the mixing of pigments during molding may be affected by many factors, such as injection speed, melt temperature, mold temperature, etc.

3. Comparison of two opportunities

1. Production efficiency and cost: Dyeing before granulation can make more efficient use of pigments and reduce waste. It can also simplify the injection molding process and improve production efficiency.

2. Color uniformity: Dyeing before granulation can usually achieve better color uniformity because the pigment is more evenly distributed in the TPR particles.

3. Flexibility: Dyeing before molding is more flexible because it allows the color to be adjusted as needed during the molding process. However, this requires additional equipment and operations, otherwise it is easy to color unevenly.

2. How to ensure uniform dyeing?

1. Prevent uneven dispersion of color powder

It is recommended to use masterbatch instead of color powder, as the dispersion effect of color powder is far inferior to that of masterbatch.

If you must use color powder, grind the color powder, mix the color manually, add diffusion oil or change the particle shape to improve the dispersion of the color powder.

2. The mold temperature should not be too low, and the release agent should be used with caution.

If the mold temperature is too low, the TPE melt will cool too quickly in the mold, forming a hard shell and affecting the color uniformity. Appropriately increase the mold temperature, reduce the cooling rate, or use local heating at the mold gate.

Excessive addition of release agent or uneven application will also cause uneven color. Try to reduce the amount of release agent used and ensure that it is evenly applied to the mold.

3. Ensure the quality of raw materials

Poor raw material quality or improper sealing may cause moisture, which in turn affects color uniformity. Choose a reliable TPE raw material supplier to ensure that the raw materials are dry and free of impurities.

4. Other points to note

Excessive injection speed, poor mold exhaust, poor thermal stability of materials, uneven plasticization, etc. may also affect uniform dyeing. It is necessary to operate according to standard preparation procedures to eliminate corresponding problems.

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