What is the reason why TPE coating adhesive is not good?
Source：德创化工Time：2020-01-04Hits：2204
TPE bag has poor adhesiveness? TPE encapsulation has a good effect. We just start to investigate from the mold, injection molding process and raw materials to find out the reason. TPE coating is more and more widely used, because TPE raw materials have the softness of rubber and are particularly comfortable to the touch. TPE is coated on the surface of hard plastic through secondary injection molding, thus improving the competitiveness of products.
The design of runner and gate should be considered in the design of flow interface size, gate location and number for some products with large encapsulation area or flow length. The core of TPE\TPR coating process is: coating while it is hot, so some designs should be conducive to the rapid completion of TPE coating.
For some materials that are difficult to coat with TPE, we suggest baking plastic parts. Nylon is overmolded by a common injection molding machine. It is suggested that nylon parts should be preheated and baked before overmolding, because nylon has strong water absorption and overmolding requires a high molding temperature. Preheating before coating can remove moisture, which is conducive to rapid hot coating.
Different hard plastics have different melting points. In addition to considering the basic polarity modification, the TPE material formula should also pay attention to the close melting point between TPE and the hard plastic coated with rubber. Only in this way can TPE and hard plastic have better adhesion. Ordinary TPE\TPR coated PP only needs an injection temperature of 170-190, but coated PA (nylon) needs 220-260.
Is TPE adhesive bad? TPE raw materials have many classifications and can be coated with ABS,PP,PS,PC,PA and other engineering plastics. There is a special formula for encapsulated ABS. If you encapsulate PP, you cannot encapsulate ABS. To purchase TPE encapsulated materials, you need to communicate with TPE manufacturers. With the in-depth development of TPE industry and the improvement of consumer demand, the secondary injection molding of TPE materials and hard plastics is increasingly widely used.
