The thermoplastic elastomer industry usually said TPE refers to the SEBS modified composite functional materials, TPE elastomer soft rubber has excellent comprehensive performance, is the secondary injection molding, overmolding shot bonding molding, two-color injection molding the most commonly used to the soft rubber materials.

　　First, TPE used in overmolding injection molding main advantages

　　1、Because TPE material has good anti-slip property and good elasticity, it can improve the touch feeling of the products and enhance the gripping property.

　　2, TPE elastomer soft rubber can be adjusted to the appropriate hardness according to the physical requirements of the product (hardness range Shore 25-90A), as well as appropriate physical properties (such as abrasion resistance, scratch resistance, adhesion, melt index, etc.). For different products provide a variety of possible material application program.

　　3、TPE is processed by overmolding and injection molding, commonly used in products such as handles, grips, electronic materials and so on. The material gives the products a comfortable touch, enhance the grip, enhance the aesthetics of the products as well as the added value of the products. Most of the products are exported to the United States, Japan and the European Union and other developed countries and regions. Because the TPE elastomer soft rubber for green raw materials, materials do not contain phthalates, halogen-free, in line with ROHS environmental testing standards, fully able to meet the United States, Japan, the European Union and other developed countries and regions of the environmental requirements!

　　Second, the main mechanism of TPE overmolded shot bonding

　　TPE overmolded shot bonding has a true overmolded and false overmolded distinction. True overlay is the use of soft rubber and hard rubber in the softening and melting compatibility (compatibility depends mainly on the material solubility parameters SP, the closer the solubility parameters, the better the compatibility of the two materials. Knowledge of SP see polymer chemistry knowledge), in the hard rubber and soft rubber contact surface to form a layer of adhesive layer, greatly enhance the TPE soft rubber and hard plastic overlay adhesion. False overmolding is almost not involved in the compatibility of the two materials, materials overmolding is through mechanical force, through the design of molds and products as well as surface treatment, through the role of hoops embedded, so that the soft rubber and hard rubber can be joined together.

　　Third, TPE overmolded shot bonding processing technology

　　TPE overmolding shot bonding is generally used in the secondary injection molding process, that is, has been beer (injection molding) good hard plastic parts fixed in the overmold, and then at the appropriate temperature will be TPE soft plastic injection molding shot bonding to the hard plastic parts, and after cooling to get the product. Overmolding injection molding temperature according to the overmolded hard plastic materials and different. Because the temperature should be considered to let the hard rubber and TPE soft rubber two materials should be softened, in order to promote the two materials in the contact surface to achieve a certain degree of compatibility. In order to achieve the effect of the real rubber, usually TPE rubber PP material injection temperature in 170-190 degrees Celsius; rubber ABS material in 220-220 degrees Celsius or so; rubber PC material temperature is slightly higher than the rubber ABS injection temperature; rubber PA nylon, then the injection temperature to 240 degrees Celsius or so.

　　Fourth, the common TPE overmolding injection molding materials

　　TPE is used in gluing shot bonding, TPE soft rubber as a soft rubber outer layer, common matching hard materials are mainly plastic, but also metal and fabric, TPE and fabric shot bonding is mainly used in luggage products, with the same as the metal gluing, generally for the false gluing. The real adhesive is mostly seen in the secondary injection molding and two-color injection molding, that is, TPE adhesive shot bonding of the main material is plastic.TPE can be commonly used with some general-purpose plastics PP, GPPS, HIPS, ABS and engineering plastics PC, PC/ABS, PA and its modified materials bonded firmly.TPE and POM polyoxymethylene adhesion, at present, in the elastomer industry, is still a difficult problem. Because of the solubility parameters of POM SP (22.6) with TPE SP (7.2-7.6) is really far apart, the two materials themselves do not have compatibility, and at present has not found to promote the two good adhesion of the appropriate compatibilizer.

　　Fifth, TPE overmolding shot adhesive molding issues to be noted

　　1. TPE and hard bonding components of compatibility needs to be matched, molecular solubility is close to the molecular compatibility is better;

　　2. Avoid sharp corners as much as possible in the design to ensure excellent contact between TPE and hard rubber parts to enhance the bonding effect;

　　3. Avoid leaving gas in the mold cavity through proper exhaust;

　　4. Balance the thickness of TPE with the desired touch;

　　5. Maintain the temperature of the TPE melt to ensure the bonding effect.

　　6. TPE material overmolding needs to be baked and reprocessed in order to reduce the surface water lines on the product surface and obtain the effect of uniform surface color;

　　7. The carrier resin of the selected masterbatch is compatible with both TPE and structural materials;

　　8. For the smooth surface should be special treatment, the purpose is to increase the soft glue and hard glue bonding contact surface, strengthen the bonding effect;

　　9. TPE should have good fluidity, because the thickness of the TPE adhesive layer and the size of the ratio is very small, TPE usually need to flow through a longer path and thin-walled area to fill the mold.

　　10.The flow length/thickness ratio of TPE is less than 150:1;

　　11. Use a good adhesive.

　　Six, common overmolding defects processing

　　Lack of glue - to improve the processing injection temperature; increase injection pressure; improve material flow.

　　Split seam, overflow edge - reduce the injection temperature; increase clamping force; reduce injection pressure; from the perspective of the formula to reduce mobility.

　　Surface pitting, not bright - to increase the injection molding temperature; baking material, reduce the moisture of raw materials.

　　Poor viscosity - fully baked material before injection processing; increase the injection temperature; adjust the formula.

　　Products injection deformation - strengthen the mold cooling; appropriate extension of clamping time.

　　Products sticky mold - add mold release agent or lubricant (for internal lubricant - mold release agent should pay attention to the amount of additives, in order to prevent the mold release agent precipitation and migration.

　　Seventh, plastic Bur TPE manufacturers experience

　　1. Sufficient injection temperature. Overmolded nylon, TPE injection temperature should be better than 190 degrees Celsius, not more than 240 degrees can be. Especially to get the effect of the real overmolding, because the softening temperature of nylon in 250-260 degrees, in order to ensure that the TPE does not degrade under the premise of TPE and nylon softening temperature is closer to the effect of overmolding the better.

　　2. The design of the structure of the rubberized parts of the product, try to achieve the size of the rounded, no obvious corners, increase the TPE and nylon hard rubber contact tightness.

　　3. In the nylon skeleton pieces of unimportant position on the opening of some small holes, or create some non-smooth surface, increase the contact area of TPE and nylon, so that the TPE soft rubber through the small holes embedded in the nylon skeleton material, to play the effect of the hoops embedded. In fact, it is the real bag and fake bag effect and use.

　　4. For the newly opened mold, need to pay attention to the mold into the gate and runner design. Because the TPE adhesive layer is generally thin, the thickness of 1-2mm is common, and the size of the adhesive layer is generally dozens or even hundreds of mm, so we must ensure that the TPE soft rubber can fill the mold cavity, not lack of rubber, not split the seam, to ensure that the TPE and nylon adhesion.