TPE overmolding PC, PP, ABS, PA and other hard plastics adhesion advantages and disadvantages of analysis has always been a matter of concern, Plastic Bo also did some homework, through the network and various aspects of the collection and collation of some information.

　　TPE overmolding secondary injection molding, through the introduction of thermoplastic elastomer TPE soft materials, to enhance the soft touch, grip, aesthetics and other functional characteristics of the product.TPE overmolding (secondary injection molding) molding, so that the TPE and the substrate to be coated (hard plastics) PP, ABS, PC, PA and so on can be a good coating adhesion.

　　To make TPE and hard plastics good adhesion, according to the principle of chemical similarity and compatibility, the key is TPE and hard plastics to have a similar polarity, so that TPE and hard plastics can occur molecular chain level fusion. Therefore, the type of hard plastics to determine the formulation of TPE, and overmolding secondary injection molding process (such as the secondary injection temperature is, etc.) directly affects the TPE and (PC, PP, ABS, PA) hard plastics adhesion is good or bad.TPE overmolding PC, PP, ABS, PA, PBT, PET, POM, and other hard plastics adhesion advantages and disadvantages of the analysis is as follows:

　　TPE overmolding material formula.

　　Different hard plastics, such as PP, PC, ABS, PA, etc., require different TPE formulations and models.

　　About different hard plastics wrapping:

　　1, ABS, PC overmolding

　　ABS, 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, so as to improve the adhesion between TPE and ABS, PC. In addition to the secondary injection molding temperature, it is recommended that 180~230℃. Specific can be adjusted according to the actual processing.

　　2、PP adhesive coating

　　PP is a very weak polarity of the plastic, and SEBS substrate TPE polarity is very close. Therefore, PP overmolding, directly using the most conventional TPE formula can be, without the need to add another polarity modifier. Although the TPE of the overmolded PP is the most common type, but the secondary injection molding temperature is also very important, it must be enough injection temperature to ensure the fluidity of the TPE and rapid coating on the surface of the PP, the injection temperature should be able to ensure that the rapid formation of a layer of fusion in the surface of the PP plastic, which is conducive to the adhesion of the TPE and PP, but not so much as to make the injection of the PP plastic parts of the thermal deformation. Plastic Bo suggests the secondary injection overmolding temperature 170~220℃. Note: PP overmolding, SBS is not recommended as TPE modified base material.

　　3、PBT、PET overmolding

　　PBT, PET semi-crystalline plastics, polarity and ABS, PC similar, PBT melting point 220 ℃, PET melting point is as high as 260 ℃, the need for TPE has a higher melt temperature. Therefore, TPE overmolding PBT and PET, the required overmolding secondary injection molding temperature is higher than overmolding ABS, PC. The bonding difficulty is greater.

　　4, PA6, PA66 overmolding

　　PA6, PA66 for semi-crystalline strong polar plastics, need a higher temperature and energy to form a fusion layer on the hard plastic surface.PA6 melting point 240 ℃, PA66 melting point 260 ℃. To form a strong bond, the need for TPE has a higher melt temperature. General TPE overmolded PA6, overmolded secondary injection molding temperature 230 ~ 250 ℃, TPE overmolded PA66, need 240 ~ 270 ℃ overmolding temperature. In addition, PA6, PA66 easy to absorb water, these are unfavorable factors for overmolding bonding.

　　5, POM overmolding

　　POM overmolding, although the melting point of POM is not high, only 180 ℃. But because of its high crystallinity, to form a fusion layer in the wrapping surface, requires high energy, at the same time due to the self-lubrication of POM, not conducive to the TPE material in the POM surface of the hard plastic parts of the rapid wrapping. Therefore, POM wrapping, in the country, I have not heard of any TPE manufacturers said to wrap firmly.

　　In short, TPE overlay PC, PP, ABS, PA, PBT, PET, POM and other hard plastics adhesive strengths and weaknesses of the analysis, depending on the TPE formula and the appropriate overlay process. In addition for PA6, PA66, PBT and other high melting point plastics, in the second injection molding before the hard plastic parts to do preheating treatment, is conducive to the adhesion of TPE and hard plastics. In the secondary injection molding using high injection temperature (to TPE for degradation as a limit), high injection speed, so that TPE has as much energy and time with PA6, PA66, PBT and other hard plastic parts to achieve the package fusion, so as to form a good adhesion.

　　Tags: tpe thermoplastic elastomer tpe raw materials tpe overmolding