Viscous adhesive composition comprising a block copolymer
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Solution Overview
Problem
Existing polymer compositions for adhesives, particularly those containing SBS or SIS, fail to achieve a balanced combination of workability and viscous adhesive characteristics, with insufficient tensile physical properties and elevated melt viscosity.
Innovation Solution
A block copolymer with a specific structure, comprising a polymer block mainly composed of a vinyl aromatic monomer unit and a polymer block mainly composed of a conjugated diene monomer unit, is used to create a polymer composition that enhances tensile physical properties and improves the balance between low viscosity and viscous adhesive characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a block copolymer composition is used to improve viscous adhesive characteristics, then peel strength is improved, but melt viscosity increases leading to deteriorated workability
Solution Approach 1:
The patent changes the molecular structure parameters of the block copolymer by controlling the polybutadiene block content (70-90 mass%) and using specific polymerization methods to achieve a balance between peel strength and melt viscosity, resolving the contradiction between adhesive characteristics and workability
Solution Approach 2:
The patent creates a composite polymer composition by combining block copolymer with specific additives and controlling the molecular weight distribution, achieving synergistic effects that improve both peel strength and maintain acceptable melt viscosity for workability
2Strength
If polymer composition is enhanced to improve tensile physical properties, then mechanical strength is improved, but viscosity increases reducing workability
Solution Approach 1:
The patent optimizes the molecular weight and molecular weight distribution parameters of the block copolymer, controlling the polybutadiene block content and using specific polymerization conditions to achieve improved tensile properties while maintaining workability through precise parameter control
Data Source
AI summary
A block copolymer comprising a polymer block (A) mainly comprising a vinyl aromatic monomer unit, and a polymer block (B) mainly comprising a conjugated diene monomer unit, the block copolymer being represented by the following general formula (1) or (2): wherein each curved portion represents a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms which is unsubstituted or optionally has a substituent, X represents a group 1 element, and "polymer" represents a polymer moiety.