Common problems and matters needing attention in TPE raw material injection molding
Time：2019-11-14Hits：2071
TPE is commonly referred to as TPU, TPEE, TPV, and TPO in a broad sense, and is referred to as Thermoplastic elastomer. In a narrow sense, TPE is a styrene based Thermoplastic elastomer, which is a blend of modified materials based on SEBS. It has the thermal plasticity of plastic and the elasticity of rubber, the appearance is natural, translucent or transparent round or cylindrical particles, the surface is sub-surface effect, the density is generally 0.9-1.3 G / CM3. 1. The main factors affecting the strength difference of TPE PRODUCTS 1. The problem of TPE raw material blending system, the kind of rubber base material, the proportion of plastic and the content of oil, etc. 2. The degradation of TPE material or the decrease of its performance after repeated use, the higher the forming temperature is, the more the processing times are, the worse the material properties including tear strength will be. 3. Stress Defect, the product has sharp inner edge or edge angle The existence of stress gap, easy to lead to stress concentration. In the case of tensile tearing, the products usually start to tear from these locations. 2. The methods of improving the strength of TPE products, for the mixed system of materials, the suggestions are as follows: A, SEBS base materials with high molecular weight and Star Structure should be selected; B, if the material properties are allowed, properly increase the proportion of plastic components such as PP, PS, LLDPE; C, properly reduce the amount of oil under the premise of ensuring physical properties; D, properly reduce the amount of calcium carbonate and other inorganic filler powder; understand the molding characteristics of materials, adopt moderate processing temperature, control the proportion of secondary material when using it, generally the proportion of secondary material is not more than 25% , avoid sharp or abrupt angle when designing products and moulds, design the corner as circular as possible, to reduce stress defects. Of course, if the SBS type alloy elastomer can not meet the requirements of material tear strength, you can consider the use of other molecular chain or substrate TPE, such as TPV, TPEE, etc. .
