Preparation and characteristics of TPE coating compound in China
Source：德创化工Time：2020-04-21Hits：1996
The elastomer industry usually refers to TPE as SEBS modified by composite functional materials. TPE ELASTOMER has excellent overall performance, is used for molding and two-color injection molding process of soft materials. 1. The main advantages of TPE FOR CLADDING MOLDING 1. Because TPE material has good skid resistance and good elasticity, it can enhance the product's touch and benefit the grip. 2. TPE can be adjusted to the appropriate hardness (Shaw Brothers Studio 25-90A) and appropriate physical properties (such as wear resistance, adhesion, melt index, etc.) . Depending on the nature of the product, a variety of possible material applications can be used for a variety of products. 3. TPE is coated, molded and processed and is commonly used in handles, handles, electronics and other products. This material gives the product a comfortable touch, enhanced grip, enhanced product aesthetic and added value. Most products are exported to developed countries and regions such as the United States, Japan and the European Union. TPE ELASTOMER is soft, green material, material does not contain phthalate, halogen, in line with ROHS environmental testing standards, can fully meet the environmental protection requirements of developed countries and regions, such as the United States, Japan, the European Union. 2. General TPE MOLDING MATERIAL TPE can be used for coating molding, two-color injection molding. TPE is a soft material, usually compatible with hard materials, mainly plastics, metals and fabrics. TPE + fabric is mainly used for luggage products. This process is the same as metal-clad forming, usually a pseudo-clad forming. True envelope molding is more common in secondary and two-color injection molding. TPE can be firmly bonded with some commonly used plastics such as PP, GPPS, HIPS, ABS and engineering plastics such as PC, PC / ABS, PA and their modified materials. Adhesion between TPE and POM is still a problem in the elastomer industry. Because the solubility parameter SP (22.6) of POM is very different from SP (7.2-7.6) of TPE, the two materials are incompatible with each other, and no suitable compatibilizer is found to promote the adhesion of the two materials. 3. Problems needing attention in injection molding of TPE ● compatibility of TPE with hard plastic components, solubility close to molecular compatibility ● avoiding sharp angle in design to ensure good contact between TPE and hard plastic and to enhance bonding effect; ● The exhaust port of cavity is set correctly, ● the thickness of TPE is balanced with the expected tactile sensation, ● the melting temperature of TPE is kept to ensure the bonding effect, ● the TPE should be dried to reduce the surface water and obtain uniform surface color; ● The carrier resin of the master batch is compatible with TPE and structural materials; ● the smooth surface after special treatment is to increase the adhesive force of the adhesive surface of soft and hard materials and to enhance the adhesive effect; ● TPE should have good fluidity, tPE molding thickness and size ratio is very small, TPE usually needs to flow through long path and thin wall area to fill die; ● TPE flow length / product thickness ratio less than 150:1; ● use good adhesives. 4. Common binder defects are treated by raising injection temperature, increasing injection pressure and improving material flow. SPLIT, overflow edge: decrease injection temperature; increase clamping pressure; decrease injection pressure; from the formulation point of view, decreased flow. Dull and dull: it increases the temperature of the molding process; it dries the material and reduces the moisture content of the raw material. Viscosity difference: Baking completely before injection; raising injection temperature; adjusting formula. Product injection deformation: strengthen the mold cooling; appropriately extend the pressure retention time. PRODUCT ADHESION: add mold release agent or lubricant (internal lubricant-mold release agent should pay attention to the amount of addition, to prevent mold release agent precipitation and fall off) . 5. Experience Sharing 1. The injection temperature is suitable, the packing nylon and the injection temperature of TPE is preferably higher than 190 °C, but not higher than 240 °C. Especially, in order to get the true coating effect, the closer the softening temperature of TPE and nylon is, the better the bonding effect is. 2. Product bonding structure design, as far as possible to achieve a smooth size, no obvious edge, increase TPE and nylon hard plastic close contact. 3. Holes are made in non-critical locations of Nylon, or non-smooth surfaces are made to increase the contact area between TPE and nylon, and holes are made with TPE soft material by imbedding nylon material. 4. For newly manufactured molds, pay attention to the design of the gate and sprue of the mold. TPE coating is usually very thin, thickness is usually 1-2mm, mold part size is usually tens or even hundreds of millimeters. It is important to ensure that TPE soft plastic can fill the cavity without lack of material, and to ensure the adhesion of TPE and nylon.
