The causes and solutions of lusterless and uneven color of TPE/TPR products

  • Time of issue:2023-02-10
  • Views:816

The causes and solutions of lusterless and uneven color of TPE/TPR products

  • Categories:Industry News
  • Author:SPP
  • Time of issue:2023-02-10
  • Views:816

  TPR/TPE and other injection molded products appear dull surface, or luster, color uneven. Troubled many people do TPE, light polishing mold, increase the back pressure; heavy reformulation, adjust the system! Here are a few reasons to analyze the insights. Only for the injection molding products program.

  (1) injection speed is too fast, the material stagnation time is too long will also cause the product surface gloss decline (mainly to produce flow lines or soluble body rupture)

  Solution to the problem: The injection speed should be reduced and the retention time should be reduced.

  (2) Poor thermal stability of the material, thermal decomposition (this should be better understood, but rarely occurs)

  Solution to the problem: Materials with good thermal stability and gloss should be selected or heat stabilizers should be added to the materials.

  (3) barrel temperature is low, the nozzle temperature is too low will also lead to a decline in the surface gloss of the product (and the fourth point is similar to the situation)

  Solution to the problem: The nozzle temperature should be raised and the melt temperature should be increased.

  (4) Mold temperature is too low, the cooling rate is too fast, when the melt is still filling the mold, a hard shell is formed on the cavity wall, the shell layer is subject to various forces, making it white and muddy, reducing the surface gloss of the product

  Solution: The surface temperature of the mold should be increased, the cooling rate should be reduced or local heating should be used at the mold gate.

  (5) The use of too much release agent will also cause such defects on the surface of the products (too much release agent, material compatibility becomes poor)

  Solution to the problem: You should try not to use or use a small amount of release agent, and apply it evenly.

  (6) Poor surface finish of the mold, so that the surface of the products without luster (polishing mold, no discussion, try not to do add glass fiber material)

  Solution to the problem: you should choose carbon tool steel and polish the surface of the mold carefully to improve the surface finish of the mold.

  (7) The back pressure when plasticizing is too small will make the material plasticize unevenly, and the material and colorant mix poorly leading to uneven surface color of the products (high-end problems, high-end solutions)

  Problem solution: back pressure should be increased appropriately.

  (8) runner, gate size is too small, poor exhaust will also cause the product surface gloss is not good (appear burnt)

  Solution: The size of runners and gates should be increased and exhaust slots should be added.

  (9) Material mixed with impurities, not dry will also make the surface gloss of the product decreased (appear water lines)

  Solution: We should remove impurities, fully dry the material, and add hopper dryer if necessary.


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