Understand the principle, technical key points or difficulties of TPE/ hard plastic wrap, now use these viewpoints or principles
Discuss the problem of wrapping glue between general plastics or engineering plastics.
(1) for general plastics such as PP,PE and ABS, the melting point/softening point of the above materials is not high in temperature
Poor polarity of character;
Next, non-polar TPE is used for injection molding. The temperature is set at a high point. The melt will melt a thin layer on the surface of these plastics.
There is no problem with the glue
(2) amorphous engineering plastics PC,PC/ABS,PPO due to the softening point temperature ratio of the above materials
Use high plastic, so TPE is required to have high melt temperature.
These materials are weakly to moderate polarity, but are also rigid plastic and amorphous. TPE does not require a lot of heat to compensate for the melting enthalpy in the crystallization zone.
(3) semi-crystalline engineering plastics, polyester (PBT,PET) are similar in polarity
The PC,PC/ABS above are semi-crystalline materials. To melt the TPE melt on the surface of rigid polyester plastics, it needs more enthalpy. Therefore, the temperature of TPE is relatively higher, and the difficulty of gluing is slightly higher than that of PC,PC/ABS.
PBT, melting point 220 ℃, PET melting point 260 ℃, TPE or higher melt temperature requirements,
It is easy to adjust TPE formula to meet the requirement of polarity and temperature resistance.
(4) a crystalline engineering plastic POM POM copolymerization POM and homopolymerization POM, melting point is not high (170 ~ 180 ℃), hard plastic melting point of TPE melt temperature requirement will not too high, heat-resistant challenge to TPE is not big, because of the high degree of crystallinity, melting TPE melt POM surface need to heat enthalpy is bigger, this heat resistance requirements for TPE is higher, and POM molecular polarity is not very strong, TPE in polarity formula is easier to adjust to achieve on the miscibility,
POM is self-lubricating material with low surface tension, which means that even if the polarity of TPE is similar and the melt temperature is high enough to melt the POM surface, the TPE melt is difficult to spread quickly and effectively on the POM surface.
It is not easy for TPE to wrap POM
(5) semi-crystalline engineering plastic nylon
Polarity is higher than all of the above common plastics, PC and PPO, PBT, PET, POM, so yes
The formulation adjustment of TPE soft glue is more difficult.
Both PA6 and PA66 are semi-crystalline and have high melting enthalpy, which also requires higher TPE melt temperature to effectively melt the hard plastic surface, and also improves the temperature tolerance requirements for TPE.
The strong polarity of PA6 and PA66 leads to water absorption and moisture absorption, which has higher requirements on the control of injection molding process.
Therefore,TPE wrapping nylon is the most difficult and crucial field in the formulation and process of wrapping glue at present, and the solution of this problem is of great guiding significance for the wrapping glue of high-performance materials.
(6) special high-temperature resistant plastic hard plastics are high-temperature plastics, such as PPS, LCP, PPA, PA46, etc
Because of high temperature plastic melting point and hot deformation temperature is very high
This requires that encapsulates the TPE melt temperature should be at least higher than these in front of the high temperature resistant hard plastic melting point above 30 ℃ was possible the junction surface melting and mixing, it difficult for the TPE is also very big.