Key Parameters for Successful TPE Overmolding on Rigid Plastic Components
Time of issue:2024-09-14
Title: Key Parameters for Successful TPE Overmolding on Rigid Plastic Components
An important application area for Thermoplastic Elastomers (TPEs) is overmolding on rigid plastic substrates. Common examples include TPE overmolding on ABS and PP, such as the TPE overmolded toothbrush handles that offer slip-resistant and soft-touch benefits. When performing TPE overmolding via secondary injection molding, the following parameters should be considered:
1. Compatibility between TPE and the rigid substrate must be ensured, with molecular solubility parameters being similar for better molecular compatibility.
2. Design should avoid sharp corners to ensure good contact between TPE and the rigid component, enhancing adhesion.
3. Proper venting should be incorporated to prevent gas entrapment within the mold cavities.
4. Balance the thickness of the TPE to achieve the desired tactile sensation.
5. Maintain the melt temperature of the TPE to ensure good adhesion.
6. Dry the TPE material before processing to reduce water streaks on the finished product's surface, resulting in a more uniform color.
7. Select masterbatches whose carrier resins are compatible with both the TPE and the substrate material.
8. Smooth surfaces should receive special treatment to increase the contact area between the soft and rigid materials, improving adhesion.
9. The TPE should exhibit good flowability, as the thickness-to-size ratio of the TPE overmold layer is small, requiring the material to flow through long paths and thin sections to fill the mold.
10. The flow length-to-thickness ratio of TPE should be less than 150:1.
11. Employ a suitable adhesive when required.
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