Styrene-Butadiene Block Copolymer Adhesive Composition
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Solution Overview
Problem
Existing hot melt adhesives, such as those based on poly(styrene-butadiene-styrene) polymers, suffer from high viscosity, poor thermal stability, and poor processability, limiting their performance in pressure-sensitive adhesive applications.
Innovation Solution
A hot melt pressure-sensitive adhesive composition comprising a block copolymer blend of a diblock copolymer with one block of monovinylaromatic hydrocarbon and one block of conjugated diene, combined with one or more block copolymers having multiple monovinylaromatic hydrocarbon and conjugated diene blocks, and a tackifying resin, which offers improved molecular parameters and processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If poly(styrene-butadiene-styrene) based adhesives are used, then adhesion performance is achieved, but viscosity is high and processability is poor
Solution Approach 1:
The patent changes the molecular parameters of the block copolymer by controlling the vinyl content of the butadiene block (15-55%) and the architecture (diblock, triblock, multiblock structures with specific polystyrene content ranges). These parameter changes reduce viscosity while maintaining adhesion performance, enabling better processability without sacrificing strength
Solution Approach 2:
The adhesive composition uses a composite approach by combining different block copolymer architectures (diblock, triblock, multiblock) with specific vinyl content ranges, creating a material that balances processability and adhesion performance better than single-structure polymers
2Strength
If poly(styrene-butadiene-styrene) based adhesives are used, then adhesion performance is achieved, but thermal stability is poor
Solution Approach 1:
The patent controls the vinyl content parameter of the butadiene block within 15-55% and adjusts the polystyrene content in specific ranges for different block structures. These parameter optimizations improve thermal stability while preserving the adhesion performance necessary for effective bonding
3Ease of operation
If block copolymer with high vinyl content is used, then processability is improved, but adhesive strength may be reduced
Solution Approach 1:
The patent identifies an optimal vinyl content range of 15-55% in the butadiene block, balancing processability and adhesive strength. Additionally, the polystyrene content is controlled within specific ranges (10-36% for diblock, 20-35% for triblock, 35-55% for multiblock) to maintain adequate adhesive strength while ensuring good processability
Solution Approach 2:
The invention uses a composite approach combining multiple block copolymer structures (diblock, triblock, multiblock) with coordinated vinyl and polystyrene content ranges, creating a synergistic material system that achieves both good processability and adhesive strength that single-component systems cannot attain
Data Source
AI summary
The present invention provides methods and systems for a hot melt pressure sensitive adhesive and thermoset that comprises from about 5 to about 50 wt.% of a block copolymer, from about 0 to about 75 wt.% of a tackifying resin, from about 0 to about 45 wt.% of an oil, and from about 0 to about 3 wt.% of an antioxidant.