How to Choose Henan Fireproof TPE Coating Material?

TPE overmolding generally uses two-shot injection molding process,

To prevent contamination of TPE raw materials and the presence of old materials or impurities in the screw and attachment recesses, especially materials with poor thermal stability, all parts should be cleaned with screw cleaner before use and after shutdown to ensure no impurities adhere.

To achieve the matte appearance characteristic of thermoset rubber surfaces, a rougher mold surface is required. Generally speaking, the rough surface produced by electrical discharge machining (EDM) of the mold cavity will result in excellent workpiece appearance and make demolding relatively easy. Abrasive methods such as steam blasting, sandblasting, or shot blasting, as well as chemical etching, can also be used to produce surfaces with different gloss and appearance.

Fireproof TPE coating material

The pre-molded (injection molded) hard plastic part is fixed on the overmolding mold, and then TPE soft rubber is injection molded onto the hard part at an appropriate temperature, and after cooling, the product is obtained. The injection temperature of overmolding varies depending on the hard plastic material being overmolded.

POM overmolding of POM. Although the melting point of POM is not high, only 180°C.

Styrenic transparent TPE is widely used in the footwear industry, largely replacing rubber; at the same time, its applications in industrial rubber products such as rubber sheets and plates are also expanding.

Diene transparent TPE, diene TPE mainly is an isomer of natural rubber, so it is also called thermoplastic trans-natural rubber. Although its heat resistance and mechanical strength are not as good as rubber, it is widely used in footwear, sponge, optical film, and other industrial rubber products due to its good transparency, weather resistance, electrical insulation, and photodegradability.

Fireproof TPE coating material

However, due to its high crystallinity, higher energy is required to form a fusion layer on the overmolded surface. At the same time, the self-lubrication 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 bond strength,

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

SEBS is the product of hydrogenation of SBS. SEBS has a saturated molecular structure, which makes its characteristics very different. It has the necessary properties for producing transparent TPE, such as aging resistance, yellowing resistance, and it also promotes excellent properties such as high temperature resistance and corrosion resistance. Only then was transparent TPE manufactured.

Fireproof TPE coating material

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