Propylene Elastomer Overmolding on ICP Substrates
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Solution Overview
Problem
There is a challenge in achieving maximum adhesion between polyolefin-based thermoplastic elastomer (TPE) compounds and acrylonitrile butadiene styrene (ABS) substrates, leading to poor bonding and limited market penetration of TPE materials in ABS-based overmolding applications, while conventional polyolefin-based materials fail to provide the desired high gloss.
Innovation Solution
Overmolding a body part comprising a propylene-based elastomer material onto a substrate made of propylene-based impact copolymer (ICP) with high gloss and impact resistance, which enhances bonding strength and compatibility, allowing for high gloss and desired properties like impact absorption and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic elastomer (TPE) compounds are used as overmolding material, then good adhesion to polyolefin-based substrates is achieved, but poor adhesion to ABS substrates results causing easy peeling
Solution Approach 1:
The patent uses polyolefin-based substrates (polypropylene or polyethylene) that are chemically homogeneous with the TPE overmolding material. This material compatibility ensures strong adhesion without peeling issues, resolving the contradiction between achieving strong adhesion and maintaining substrate compatibility by selecting substrates from the same polymer family.
Solution Approach 2:
The patent specifies precise compositional parameters for the TPE compound (polymer matrix type, rubber particle content of 10-40 wt%, specific glass transition temperature ranges) to optimize adhesion strength while maintaining compatibility with polyolefin substrates, thereby resolving the adhesion-versatility contradiction through controlled material parameters.
2Strength
If conventional polyolefin-based materials are used, then good adhesion is achieved, but high gloss surface is not provided
Solution Approach 1:
The patent applies a clear coat layer (5-20 micrometers thick) over the TPE overmolding to provide the high gloss surface finish. This local quality enhancement adds the desired optical property to the specific surface area without altering the bulk adhesion properties of the TPE-substrate bond, thereby resolving the contradiction between adhesion strength and surface gloss.
3Illumination intensity
If ABS substrate is used, then high gloss surface is achieved, but poor adhesion with TPE overmolding material results
Solution Approach 1:
The patent eliminates the use of ABS substrate and replaces it with polyolefin-based substrates that are chemically homogeneous with the TPE overmolding material. This material matching ensures strong adhesion while the clear coat layer is applied to provide the high gloss surface, thereby resolving the contradiction between gloss and adhesion by changing the substrate material family.
Solution Approach 2:
The patent introduces a clear coat layer as an intermediary between the TPE overmolding and the external environment. This clear coat serves as the surface that provides high gloss while the TPE-substrate interface maintains strong adhesion, effectively mediating between the requirements for gloss and adhesion strength.
Data Source
AI summary
Disclosed are propylene-based articles which can provide desired glossy surface including an impact copolymer substrate and a propylene-based elastomer body part overmolding, and a method of making such articles.