Suggestions to improve the adhesive property of TPE covered nylon

　　TPE covered nylon (mainly refers to PA6, PA66 and its fiber modified engineering plastics), mainly used in kitchen utensils handle, electric drill tool handle, electrical products accessories, etc. TPE soft rubber can be modified through the formula to adjust the hardness, TPE soft rubber for covered nylon, the general hardness range in ShoreA40 ~ 80 degrees, with hardness of about 60 degrees is most common. TPE and nylon PA composite injection molding / overmolding, generally using two-color injection molding machine or ordinary injection molding machine (need to open two sets of molds, one set of mold injection nylon parts, the other set of molds for TPE soft rubber overmolding to PA nylon surface, first injection nylon parts, and then TPE injection sticky injection to the surface of nylon parts) and other equipment to complete. At present, many users often encounter the problem of poor adhesion between TPE and nylon when making TPE covered nylon products.

　　Analysis of the bonding property of TPE coated nylon PA

　　At present, in the domestic TPE elastomer modification industry, different TPE elastomer manufacturers have different technical maturity of TPE bonding nylon PA material. From the analysis of material properties, TPE and nylon PA bonding itself has a certain degree of difficulty, because the two materials microscopic molecular polarity gap is large, their own compatibility is poor, need to introduce grafting materials can improve the adhesion of TPE and nylon, which refers to the material formulation point of view. Then is from the material processing, must make TPE and nylon materials with similar processing temperature, such as PA nylon injection molding processing temperature in 250 ~ 260 degrees, then, the second injection molding TPE, TPE molding processing temperature should be close to this temperature, to reach about 240 ~ 250 degrees, close to but slightly lower than the nylon injection temperature.

　　TPE and PA nylon bonding is not good to improve the approach

　　1. from the formulation point of view, can improve the compatibility of TPE and PA, so as to enhance the bonding between the two;

　　2. appropriately increase the TPE injection processing temperature. The TPE of nylon PA has a high plasticization temperature, so there must be enough TPE processing temperature to achieve the temperature conditions necessary for good bonding between TPE and nylon PA;

　　3. preheating treatment of nylon parts before secondary injection. The actual TPE material in the nylon processing process, you can first PA nylon parts with oven heating, and then while hot into the package mold, TPE material immediately injection molding up, can improve the bonding properties of TPE and nylon;

　　4. Start from product design. You can punch a hole at an insignificant position on the nylon parts and set a serrated groove at the edge of the soft rubber covering position, which can improve the bonding of TPE and PA by embedding injection or increasing the contact surface of TPE and PA.