Shanghai TPE Two-Color Injection Molding Options

TPE overmolding generally adopts a two-shot injection molding process,

TPE is a classic aggregation-induced emission molecule, meaning it has no fluorescence in solution but strong fluorescence in solid state, so transparent TPE materials also have important applications in fields such as organic optoelectronics.

Olefin-based transparent TPE has good weather resistance and ozone resistance, making it the fastest-growing variety of TPE. It is mainly used as a key rubber material in fields such as automotive and home appliances.

TPE Two-Color Injection Molding

Fix the already injection-molded hard plastic part onto the overmolding mold, then at a suitable temperature, inject and bond the soft TPE material onto the hard plastic part, and cool to obtain the product. The injection temperature for overmolding varies depending on the hard plastic material being overmolded.

POM overmolding on POM. Although POM has a low melting point of only 180°C.

Since any impurities in the TPE material can affect the transparency of the product, it is necessary to pay attention to sealing during storage, transportation, and feeding to ensure the TPE raw material is clean. Especially if the TPE raw material contains moisture, heating will cause the material to deteriorate, so it must be dried. During injection molding, a drying hopper must be used for feeding.

Transparent grades are divided into transparent and translucent series, each with various hardness levels; excellent transparency; smooth and soft surface; good anti-yellowing performance, tear resistance, good tensile strength; environmentally friendly; suitable for various transparent series products.

TPE Two-Color Injection Molding

However, due to its high crystallinity, forming a fusion layer on the overmolding surface requires high energy. At the same time, the self-lubricating property of POM is not conducive to the rapid overmolding of TPE material on the surface of POM hard plastic parts.

Preheating the insert before overmolding helps improve bonding strength,

SEBS is the product of hydrogenation of SBS. SEBS has a saturated molecular structure, which leads to very different characteristics. It has the necessary aging resistance, yellowing resistance, and other properties required for producing transparent TPE, and also contributes to excellent high-temperature resistance and corrosion resistance. This is how transparent TPE is manufactured.

Thickness of the TPE/TPR overmolding layer. In most overmolding applications, a wall thickness in the range of 1.5-3.0mm will ensure good bonding. If the TPE layer is too thin, injection molding is difficult, bonding strength is low, and the feel is poor. If the TPE layer is too thick, on the one hand, the cost is high, and on the other hand, defects such as shrinkage and bubbles are prone to occur.

TPE Two-Color Injection Molding

Because the preheating process can improve the compatibility between the insert material and TPE. The appropriate temperature for the insert needs to be discussed and determined with the material supplier.