Why does TPE-coated PP not bond well? Let me tell you

Time：2020-06-03Hits：2442

TPE coated PP adhesive effect is not good, can not stick, a hard tear on the open! On June 3, 2020, a customer contacted me through the Internet and asked me this question. However, the market application of TPE-coated PP materials is very mature now, so we will analyze this problem today! This is a common problem encountered by many plastic-coated injection molding plants. Everyone knows TPE material feels comfortable and its hardness and density can be adjusted at will. Therefore, TPE coating materials can be seen in many product designs. As small as a pen, as large as car accessories. The coated substrate also extends from the simplest PS and PP to hard plastics such as PC, PA and ABS. Injection Molding Process of TPE Encapsulated PP Material; 1. When the hard plastic is injected in the first step, it is still hot, and immediately enters the second cavity of 2K injection molding machine. The intermediate transfer process also does not absorb moisture. It is easy to ablate ultra-thin layer on the surface by high-temperature TPE melt, and there is no influence of water vapor adsorption on the surface. 2. Within the allowable processing range of TPE materials, choose higher injection molding temperature and barrel (melt) temperature as much as possible, otherwise TPE will easily have enough heat to ablate the surface of hard plastic materials. 3, hard plastic as insert mold cavity as high as possible mold temperature. When the hard plastic temperature is high, the TPE high-temperature melt cools slowly, with enough heat and enough time to ablate the hard plastic to form a mutually soluble ultra-thin layer. 4. On the premise of no flash of TPE material, the TPE melt shall be injected at a high firing rate as much as possible. High firing rate, short spreading time of TPE on hard plastic surface, longer ablation time on hard plastic surface in molding cycle. 5. Increase injection speed. Friction between TPE melt and hard plastic surface causes frictional heat generation. Temperature cooling of TPE melt also slows down, and it is used to contact and ablate hard plastic surface for a longer time. 6. Rapid injection molding. Most TPE (except TPU, TPU melt viscosity is more sensitive to temperature) melt viscosity shear thinning and surface tension decrease, which is conducive to spreading on hard plastic surface. 7. Polar hard plastics such as PC, PBT, PET, POM, especially strong polar hard plastics such as nylon 6 and nylon 66, moisture absorption on the surface leads to the formation of hydrogen bonds with adsorbed water molecules, TPE cannot effectively form intermolecular bonds with molecules on the surface of the hard plastics, and the bonding force of natural encapsulation decreases. The above 7 points are the injection molding process analysis of TPE-coated PP materials, hoping to help more people. If you are developing TPE-coated PP, TPE-coated PP, TPE-coated ABS, TPE-coated PC, TPE-coated POM, TPE-coated PA66, TPE-coated PS ... TPE-coated materials with different properties can be customized according to customer requirements, please call for advice!

德创化工 (edit：dechuang)