Analysis of tpe material covering type
Time of issue:2023-06-19
1. The bonding of TPE overlays is mainly classified as follows:
Institutional bonding (physical), chemical bonding, ionic bonding
mechanical latch design difficulty is low if the chemical compatibility is good, if the compatibility is poor and chemical bonding is not available, it is difficult to design the latch;
TPE is mainly used for the following plastic overmolding: PP, PE, PMMA, copolymer PE, PET, PC, PC/ABS, ABS, POM, HIPS, PPO, nylon (PA), ASA
2. Overview of various overmolding
2.1 PP cover
PP is a very weak polarity plastic, and the polarity of TPE is very close to that of SEBS base material. Therefore, the most conventional TPE formulation can be directly used for PP overmolding without adding additional polarity modifiers. Although TPE is the most common type of PP, the secondary injection molding temperature is also very important to ensure the fluidity of TPE and fast coating on the surface of PP with sufficient injection temperature. The recommended temperature for secondary injection molding is 170~220℃. Note: PP overmolding, SBS is not recommended as TPE modified base material.
2.2 ABS, PC overmolding
ABS and PC are weak to medium polarity plastics, and there is a certain polarity difference with TPE. By adding modifier (TPU) in the formula, the polarity of TPE can be improved, thus improving the adhesion of TPE with ABS and PC. In addition, the secondary injection temperature is recommended to be 180~230℃. The specific can be adjusted according to the actual processing situation.
2.3 PBT, PET overmolding
PBT, PET semi-crystalline plastic, polarity and ABS, PC, PBT melting point 220 ℃, PET melting point is as high as 260 ℃, TPE needs to have a higher melt temperature. Therefore, the TPE overmoulding PBT and PET, the required overmoulding secondary injection temperature is higher than overmoulding ABS and PC. Bonding is more difficult.
2.4 PA6, PA66 overmolding
PA6, PA66 for semi-crystalline strong polar plastic, requires high temperature and energy to form a fusion layer on the surface of the hard plastic. PA6 melting point of 240 ℃, PA66 melting point of 260 ℃. To form a strong bond, the TPE needs to have a higher melt temperature. Generally, TPE overmelt PA6, overmelt secondary injection temperature 230 ~ 250 ℃, TPE overmelt PA66, the need for 240 ~ 270 ℃ overmelt temperature. In addition, PA6, PA66 easy to absorb water, these are unfavorable factors for overmolding bonding.
2.5 POM overmolding
POM overmolding, although the melting point of POM is not high, only 180 ℃. But due to its high crystallinity, to form a fusion layer on the cladding surface, requires high energy, while the self-lubricating nature of POM, is not conducive to TPE material in the POM hard plastic parts on the surface of the fast cladding.
Tags: tpe thermoplastic elastomer tpe raw material transparent TPE
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