Thermoplastic Elastomer Composition for Fluidity and Sag Resistance
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Solution Overview
Problem
The existing thermoplastic elastomer compositions, particularly those using paraffin-based mineral oil, suffer from inadequate sag resistance and permanent elongation when used with styrene-based block copolymers of weight-average molecular weight around 100,000, which affects their fluidity and moldability.
Innovation Solution
A thermoplastic elastomer composition is developed, incorporating a specific ethylene/α-olefin copolymer with defined kinematic viscosity and molecular weight ranges, combined with a block copolymer and a polyolefin-based resin, to enhance fluidity, softness, and sag resistance, including compression set and permanent elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If paraffin-based mineral oil is used as a softener for TPS, then softness and fluidity are improved, but sag resistance such as compression set and permanent elongation deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight (1,000 to 30,000) and kinematic viscosity at 100°C (5 to 5,000 mm²/s) of the ethylene/α-olefin copolymer. By adjusting these parameters within specific ranges, the composition achieves optimal balance between fluidity during molding and sag resistance in the final product, resolving the contradiction between ease of operation and reliability
Solution Approach 2:
The patent uses composite materials by combining ethylene/α-olefin copolymer with styrene-based block copolymer and polyolefin-based resin in specific weight ratios. This composite approach allows the mixture to exhibit both good fluidity (from the copolymer) and excellent sag resistance (from the synergistic interaction with block copolymer and polyolefin resin), simultaneously improving ease of operation and reliability
2Productivity
If SBC with weight-average molecular weight of about 100,000 is used to improve moldability, then fluidity is improved, but sag resistance such as compression set and permanent elongation deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the weight-average molecular weight of SBC within a specific range (30,000 to 500,000) and combining it with ethylene/α-olefin copolymer having molecular weight of 1,000 to 30,000. This dual molecular weight control strategy enables the composition to achieve both high moldability (from lower molecular weight components providing fluidity) and good sag resistance (from higher molecular weight SBC providing structural integrity)
Solution Approach 2:
The patent uses composite materials by creating a multi-component system where SBC (30-100 parts), ethylene/α-olefin copolymer (1-400 parts), and polyolefin-based resin (0-200 parts) work synergistically. The composite structure allows different components to contribute different properties: SBC provides base elastomeric properties and moldability, while the copolymer and polyolefin resin enhance sag resistance, resolving the contradiction between productivity and reliability
Data Source
AI summary
A thermoplastic elastomer composition including 100 parts by mass of a block copolymer containing a polymer block (X) having an aromatic vinyl compound as a main component and a polymer block (Y) having a conjugated diene compound as a main component, or a hydrogenated product thereof (A); 1 to 400 parts by mass of an ethylene/α-olefin copolymer (B) satisfying the following requirements (b-1) to (b-3); and 0 to 200 parts by mass of a polyolefin-based resin (C) satisfying the following requirement (c-1), (b-1) a kinematic viscosity at 100° C. is 5 to 5,000 mm2/s and a kinematic viscosity at 40° C. is 50 to 100,000 mm2/s, (b-2) a weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is 1,000 to 30,000, (b-3) a content ratio of ethylene structural units is 15 to 85 mol %, and (c-1) MFR (230° C. and 2.16 kg) is 0.1 to 500 g/10 min.