Whether insert injection molding or over molding is selected, thermoplastic elastomer (TPE) is injected on a compatible rigid substrate. This enhances the function of "soft package covered hard" goods, such as insulation, chemical resistance, more ergonomic, better hand feel, grip and top-notch beauty.

Insert molding: in insert molding, first make rigid parts (generally hard plastic parts), insert them into the mold cavity, and then use TPE injection molding on this component to finally obtain intact goods. Conventional injection molding equipment can be used for insert molding. The placement of rigid parts can be completed by manual or mechanical arm.

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over molding: over molding is also called secondary injection molding, two-color molding or multi-material molding. The special machine used in this case has multiple barrels, which are used to write different data into the same mold.

Adhesion in compound injection molding in compound injection molding, the adhesion between solid substrate and TPE is the key to the success of processing. Poor adhesion can cause problems such as peeling, bending, wear or delamination. The compatibility between the two materials and processing temperature are important factors affecting the bond strength.

Data compatibility: bond strength of different hard / soft data 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 (TPE-E or cope) based on polyester is produced by DSM engineering plastics.

This kind of polyester elastomer combines the strength, processing characteristics and thermosetting elastomer functions of engineering plastics, and improves processing, yield and chemical resistance.

Most soft touch compound injection molding applications involve injecting a thin layer of soft material (TPE) onto a hard substrate. Because TPE generally needs to flow through longer channels and thin-walled areas to fill the mold, TPE has to have high fluidity. The low viscosity commodity specification optimizes the adhesion that is crucial for compound injection molding and is the preferred material for this processing application.

Chemical bonding: TPE is well bonded with polar polymers (such as PC, PC / ABS, ABS) used as rigid substrates through compound injection molding. Because of this excellent adhesion, even when the torque is very large, it will not show the appearance of delamination with the substrate.

In the process of selecting surface elastomer, TPE has excellent layout characteristics and excellent appearance feeling function, and relates to the outstanding processing function of TPE in compound injection molding. Physical combination or application of binder: mechanical interlocking is often used to improve the combination force with the substrate during compound injection molding 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.