Thermoplastic Polyether Block Amide Silicone Elastomer Hardness Control
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Solution Overview
Problem
It is challenging to produce thermoplastic elastomer compositions with low Shore A hardness values below 90, 85, or 80 without using plasticizers or compatibilizers, while maintaining impact resistance and mechanical properties.
Innovation Solution
A thermoplastic elastomer composition comprising a blend of thermoplastic organic polyether block amide copolymer, a silicone composition with a diorganopolysiloxane polymer and reinforcing filler, an organohydrido silicone compound, and a hydrosilylation catalyst, where the weight ratio of the copolymer to the silicone composition is between 50:50 to 95:5, allowing for curing and achieving low hardness without plasticizers or compatibilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If plasticizers or compatibilizers are used to reduce hardness, then Shore A hardness decreases, but the material requires additional additives and processing complexity
Solution Approach 1:
The invention extracts and eliminates the need for plasticizers and compatibilizers from the formulation by using a specific blend of thermoplastic polyurethane and silicone elastomer where the silicone carbodiimide crosslinking system inherently provides the desired hardness reduction without requiring additional additive systems
Solution Approach 2:
The silicone elastomer acts as an intermediary component that, when crosslinked with carbodiimide, modifies the hardness of the thermoplastic polyurethane matrix without requiring traditional plasticizers, thereby mediating between the need for structural integrity and softness
2Ease of operation
If plasticizers are added to achieve low Shore A hardness, then hardness decreases, but impact resistance and mechanical properties deteriorate
Solution Approach 1:
The invention uses a controlled amount of silicone elastomer that is crosslinked in situ to provide temporary plasticizing effect during processing, but the crosslinked structure remains to maintain mechanical strength and impact resistance, avoiding the permanent degradation associated with traditional plasticizers
Solution Approach 2:
The invention creates a composite material system combining thermoplastic polyurethane with carbodiimide-crosslinked silicone elastomer, where the synergistic interaction between the two components achieves low hardness while maintaining or improving mechanical properties through the crosslinked network structure
3Ease of manufacture
If conventional thermoplastic elastomer blends are used, then processing is simplified, but oil and solvent resistance and compression set properties are insufficient
Solution Approach 1:
The invention changes the chemical parameter of the elastomeric phase by introducing carbodiimide crosslinking, which transforms the physical blend into a chemically bonded network, thereby improving oil and solvent resistance and compression set properties while maintaining thermoplastic processability
Solution Approach 2:
The invention utilizes the phase transition behavior of the thermoplastic polyurethane matrix (melting and solidification) while the crosslinked silicone elastomer phase remains stable, allowing the material to be processed in the molten state and then set into a durable crosslinked structure that resists degradation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting material maintains impact resistance and mechanical performance with a Shore A hardness below 90, 85, or 80, achieving a soft touch feel and improved durability without the need for plasticizers or compatibilizers.
Implementation Method 1
an organohydrido silicone compound and a hydrosilylation catalyst, wherein the weight ratio of the thermoplastic organic polyether block amide copolymer to the silicone composition is between 50:50 to 95:5
Data Source
AI summary
A thermoplastic elastomer composition comprising a blend of (A) a thermoplastic organic polyether block amide copolymer, (B) a silicone composition comprising (B1) a silicone base comprising (B1a) a diorganopolysiloxane polymer having a viscosity of at least 1000000 mPa·s at 25° C. and an average of at least 2 alkenyl groups per molecule and (B1b) a reinforcing filler in an amount of from 1 to 50% by weight based on the weight of (B1a), (B2) an organohydrido silicone compound which contains an average of at least 2 silicon-bonded hydrogen groups per molecule, (C) a hydrosilylation catalyst, and optionally: one or more additives component (D), wherein the weight ratio of thermoplastic organic polyether block amide copolymer (A) to the silicone composition (B) is in the range 50:50 to 95:5, and wherein component (B2) and (C) are present in an amount sufficient to cure said silicone composition (B1).