Adhesive composition
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Solution Overview
Problem
Existing adhesive compositions exhibit a significant rise in adhesive strength after bonding, making bonding adjustment difficult.
Innovation Solution
An adhesive composition comprising a block copolymer with specific mass ratios and acid values, composed of polymer blocks A, B, and C, which includes (meth)acrylate ester units with linear or branched side chains, and aromatic vinyl compound units, allowing for microphase separation and pseudo crosslinked structures to control adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive composition containing a polyvalent metal and a thermoplastic resin having at least one type of functional group selected from the group consisting of an amino group and salts thereof is used, then adhesive strength is improved, but bonding adjustment becomes difficult due to considerable rise in adhesive strength following bonding
Solution Approach 1:
The invention changes the chemical composition parameters of the adhesive by specifying a block copolymer with particular (meth)acrylate ester units having linear or branched side chains of 1 to 8 carbon atoms, with controlled mass ratios between polymer blocks and acid values of at least 8 mgKOH/g. This parameter optimization enables the adhesive to achieve satisfactory strength while minimizing post-bonding strength rise, thereby facilitating bonding adjustment.
Solution Approach 2:
The invention uses a composite block copolymer structure comprising multiple polymer blocks (A, B, and C) with different functional characteristics. Block A provides adhesive functionality, Block B contributes structural properties, and Block C modulates the adhesive strength profile. This composite structure achieves both satisfactory adhesive strength and controlled strength rise, enabling easy bonding adjustment.
2Reliability
If adhesive strength is increased to ensure satisfactory bonding, then bonding reliability is improved, but bonding adjustment capability deteriorates due to difficulty in repositioning
Solution Approach 1:
The invention optimizes specific parameters of the block copolymer including the acid value (at least 8 mgKOH/g), the mass ratio between polymer blocks, and the molecular structure of (meth)acrylate ester units. These parameter changes create an adhesive that achieves reliable bonding while maintaining adequate repositionability for bonding adjustment.
Solution Approach 2:
The invention introduces local quality differences within the adhesive molecule through the block copolymer structure, where different polymer blocks provide different local functions. This localized functional differentiation allows the adhesive to exhibit both strong bonding reliability and controlled adjustability in different operational phases.
Data Source
AI summary
An adhesive composition of one aspect of the present invention contains a block copolymer composed of a polymer block A which includes a (meth)acrylate ester unit having a linear or branched side chain of 1 to 8 carbon atoms and has a number average molecular weight of 2,000 to 10,000, a polymer block B which includes at least one of an aromatic vinyl compound unit and a (meth)acrylate ester unit having a cyclic structure, and a polymer block C which includes a (meth)acrylate ester unit having a linear or branched side chain of 1 to 8 carbon atoms, wherein the mass ratio (B/C) between the polymer block B and the polymer block C is within a range from 5.0/95.0 to 30.0/70.0, the mass ratio (A/(B+C)) between the polymer block A and the total of the polymer block B and the polymer block C is within a range from 0.1/99.9 to 5.0/95.0, and the acid value of the block copolymer is at least 8 mgKOH/g.