Properties of PC encapsulation material bonded by TPE secondary injection molding in Dechuang Chemical Industry.
Time：2021-09-24Hits：1569
TPE material is the general name of Thermoplastic Elastomer, and its English full name is thermoplastic elastomer. It is a kind of functional material with rubber elasticity and plastic stiffness, which can be directly injection molded. Generally, the encapsulated TPE material refers to TPE-S, i.e. polystyrene thermoplastic elastomer, which is a thermoplastic engineering plastic obtained by composite modification with SEBS or SBS elastomer as the base material. TPE-S elastomers are generally called TPE or TPR in the elastomer industry.
1. concept of TPE encapsulation:
TPE encapsulation, as its name implies, is to encapsulate TPE soft rubber material onto other materials. Generally, the processing methods are one-step molding with two-color injection molding machine, or two-step injection molding with general injection molding machine and rubber-coated mold. The products molded by TPE are generally handles and handlebars. Because of the special comfortable touch of TPE soft rubber material, the introduction of TPE material improves the grip and touch feel of products.
Second, the TPE material concept:
TPE material is the general name of Thermoplastic Elastomer, and its English full name is thermoplastic elastomer. It is a kind of functional material with rubber elasticity and plastic stiffness, which can be directly injection molded. Generally, the encapsulated TPE material refers to TPE-S, i.e. polystyrene thermoplastic elastomer, which is a thermoplastic engineering plastic obtained by composite modification with SEBS or SBS elastomer as the base material. TPE-S elastomers are generally called TPE or TPR in the elastomer industry.
Iii. characteristics of TPE encapsulated PC material:
TPE thermoplastic elastomer is SEBS rubber modified material, which has rubber elasticity and can be easily molded by injection or extrusion. The hardness range of the compound can be adjusted from 0 to 100 degrees Shorea. The common hardness of TPE compound used for encapsulating PC ranges from 30 to 80 degrees, and its appearance is natural color or translucent particles. The rubber material has excellent wear resistance and good adhesion with PC coating, and the manufactured product feels comfortable and smooth.
Iv. TPE encapsulated PC processing method:
Generally, the conventional molding method is adopted for TPE encapsulated PC, that is, two sets of molds are used, one for injecting PC products first, and the other for injecting TPE compound onto the surface of PC products. This kind of molding method is called secondary injection molding, overmolding or insert injection molding. It can also be processed by a more advanced two-color injection molding machine, and the results are the same. TPE and PC are bonded together by injection molding. The injection temperature of injection molding is different according to the hard rubber material of injection molding. Because the temperature should be considered to soften both hard rubber and TPE soft rubber, the two materials can be made compatible at the contact surface. In order to achieve the true encapsulation effect, the injection temperature of TPE encapsulated PP material is usually about 170-190℃. Rubber-coated ABS material is about 220-220℃; The molding temperature of encapsulated PC is slightly higher than that of encapsulated ABS.
V. The main advantages of TPE in injection molding.
1.TPE elastomer soft adhesive is applied to secondary injection molding, and it is coated and glued. Because TPE material has good skid resistance and good elastic touch, it can improve the touch feel of products and enhance the grip.
2.TPE elastomer soft rubber can be adjusted to appropriate hardness (hardness range Shore 25-90A) and appropriate physical properties (such as abrasion resistance, scratch resistance, adhesion, melt index, etc.) according to the physical property requirements of products. Various possible material application schemes are provided for different products.
3.TPE is processed by injection molding, and commonly used products such as handles, grips and electronic materials. The material endows the products with comfortable touch, improves the grip, and enhances the aesthetics and 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. As TPE elastomer soft rubber is a green raw material, the material does not contain phthalate, halogen and 38 SVHC substances of very high concern specified by REACH. Comply with ROHS,REACH,NP,EN71,PAHS environmental testing standards, and fully meet the environmental protection requirements of developed countries and regions such as the United States, Japan and the European Union.
Six, TPE encapsulation materials are:
TPE can adhere firmly to some commonly used general plastics PP,GPPS,HIPS,ABS and engineering plastics PC,PC/ABS,PA and their modified materials, and can also be molded separately.
TPE encapsulated PC application:
TPE encapsulated PC is mainly used for encapsulating electronic and electrical accessories such as hardware tool handles, mobile phone protective covers, game machine handles, interphone housings and instrument housings. Generally, TPE with hardness of 60~80 degrees is used for the encapsulation of such products, while TPE compounds with different hardness and physical properties may be used for other special products.
Seven, TPE encapsulation common encapsulation defects treatment:
1. lack of glue-increase the processing and injection molding temperature; Increase injection pressure; Improve material fluidity.
2. Splitting and edge overflow-reducing the injection molding temperature; Increase the clamping force; Reduce injection pressure; Reduce fluidity from the perspective of formula.
3. Plastic injection deformation of products-strengthening mold cooling; Appropriately extend the mode locking time.
4. Sticking products to mold-adding release agent or lubricant, modifying mold and adjusting formula.
5. There are water marks-bad exhaust and low injection temperature; Solution: Improve exhaust and injection temperature;
6. The viscosity between TPE and PC is not good-adjust the TPE formula;
7.TPE is easy to scratch and whiten-adjust TPE formula.
8.TPE has poor surface gloss, pitted surface-unbaked material, low injection temperature and insufficient plasticization; Solution: Bake the material and raise the injection temperature.
德创化工 (edit：dechuang)
