Compound injection molding can be used to enhance product functionality, such as improved chemical resistance, increased grip, softer and more attractive handle.
The double injection molding technique was initially used to beautify the appearance of consumer goods and is now quite popular. This skill has been used in various applications, and can even be used to enhance the functionality of the product, such as improving chemical resistance, enhancing grip, softer and more attractive handle.
Double injection molding skills: the commonly used information in compound injection molding is thermoplastic elastomer (TPE). The variety of materials that can be used for compound injection molding has been greatly added. For the compound injection molding on the base materials (such as ABS, PC, PC / ABS, PA and San), SEBS, tpe-v, tpe-u, TPE-E and tpe-a are widely used.
Whether it is insert injection molding or secondary injection molding, thermoplastic elastomer (TPE) is injected into the compatible rigid substrate. This makes the "soft cover hard" products more functional, such as insulation, chemical resistance, more ergonomic, better feel, grip and top-notch aesthetic feeling.
Insert molding: in insert molding, a rigid part (usually a relatively hard plastic part) is made and embedded into the mold cavity. Then, TPE injection molding is used on this component to obtain a good product. Conventional injection molding equipment can be used for insert molding. The placement of rigid parts can be completed by manual or mechanical arm.
Secondary injection molding: secondary injection molding is also called double injection molding, double color molding or multi material molding. The special machine used in this case has multiple drums, which are used to write different data to the same mold. In compound injection molding, the bonding between solid base material and TPE is the key to the success of processing. Poor adhesion can lead to problems such as peeling, bending, wear or delamination. The compatibility between the two materials and processing temperature are the important factors affecting the bond strength.
Material compatibility: bond strength of different hard / soft material combinations
Processing temperature: it reflects the relationship between TPE melting temperature, rigid substrate temperature and bond strength. Application of TPE in compound injection molding thermoplastic elastomer based on polyester (TPE-E or cope) is produced by DSM engineering plastics. This kind of polyester elastomer combines the strength and processing characteristics of engineering plastics as well as the function of thermosetting elastomer, which improves the processing, yield and chemical resistance.
Most of the soft handle applications of duplex injection involve the injection of a thin layer of soft material (TPE) onto a hard substrate. Because TPE generally needs to flow through a long path and thin wall area to fill the mold, TPE has to have high fluidity. The low viscosity product specification optimizes the critical adhesiveness for compound injection molding and is the preferred information for this processing application.
Chemical bonding: TPE is well bonded with polar polymers (such as PC, PC / ABS, ABS) used as rigid substrate after compound injection molding. Because of this excellent adhesion, even in the case of very high torque, it will not show the appearance of delamination with the substrate.
In the process of selecting exterior elastomer, TPE has excellent layout characteristics and excellent appearance perception function, and relates to the outstanding processing function of TPE in compound injection molding. Application of physical combination or binder: mechanical interlocking is often used to improve the joint force with substrate when double injection molding is performed between TPE and non-polar polymer (such as PP) or Pa. In addition, adhesive or primer can be used to improve the adhesion between flexible TPE and non-polar polymer
