Acrylic Block Copolymer Adhesive Composition for High-Temperature Holding
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Solution Overview
Problem
Existing pressure-sensitive adhesives containing acrylic block copolymers lack durability, whitening resistance, and adhesive force, particularly at high temperatures and on glass surfaces, and suffer from adhesion acceleration issues.
Innovation Solution
A pressure-sensitive adhesive composition comprising an acrylic block copolymer with specific molecular weight ranges and mass ratios of methacrylic acid ester and acrylic acid ester units, combined with a tackifying resin, to enhance cohesive force, transparency, and compatibility, while maintaining low viscosity for improved coating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If acrylic block copolymers are used as pressure-sensitive adhesives, then coating properties and pressure-sensitive adhesion properties are improved, but durability, cohesive force at high temperatures, and holding power are insufficient
Solution Approach 1:
The patent changes the molecular weight parameters of the acrylic block copolymer, specifically setting Mw to 30,000-300,000 and Mw/Mn ratio to 1.05-1.30, to achieve optimal balance between coating properties and durability. This parameter optimization resolves the contradiction by finding the precise molecular weight range that satisfies both ease of coating and long-term reliability requirements.
Solution Approach 2:
The patent creates a composite adhesive system by combining acrylic block copolymer with tackifying resin in specific proportions (resin content 5-50 parts by mass per 100 parts of copolymer). This composite approach allows the acrylic block copolymer to provide coating properties while the tackifying resin enhances durability and cohesive force, resolving the contradiction between ease of operation and reliability.
2Strength
If acrylic block copolymers with specific compositions are used, then pressure-sensitive adhesion properties are improved, but adhesive force to glass and holding power at high temperatures are insufficient
Solution Approach 1:
The patent optimizes the compositional parameters of the acrylic block copolymer, including the ratio of polymer blocks A and B (5-95 mass% A, 5-95 mass% B) and the molecular weight distribution (Mw/Mn = 1.05-1.30), to achieve simultaneous improvement in pressure-sensitive adhesion and high-temperature holding power. The specific compositional parameters create an adhesive that maintains strength across temperature variations.
3Reliability
If pressure-sensitive adhesives are designed for high adhesive force, then durability is improved, but whitening resistance and adhesion acceleration resistance are insufficient
Solution Approach 1:
The patent carefully controls the molecular weight parameters (Mw = 30,000-300,000, Mw/Mn = 1.05-1.30) and compositional parameters of the acrylic block copolymer to achieve a balance where the adhesive maintains strong bonding durability while resisting whitening and adhesion acceleration. The narrow molecular weight distribution and specific block composition prevent degradation phenomena under stress.
Data Source
AI summary
There are provided a pressure-sensitive adhesive composition which is excellent in durability, whitening resistance, hot-melt processability, pressure-sensitive adhesion properties, holding power at high temperatures, heat resistance, weathering resistance, compatibility with tackifying resins, low-temperature properties and transparency, is excellent also in balance of these properties and rarely suffers adhesion acceleration, and pressure-sensitive adhesive products using the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition comprises an acrylic block copolymer (I) having a polymer block (A) comprising methacrylic acid ester units and a polymer block (B) comprising acrylic acid ester units which are derived from an acrylic acid ester (1) represented by the general formula CH2=CH-COOR1 (1) (wherein R1 is an organic group of 4 to 6 carbon atoms) and an acrylic acid ester (2) represented by the general formula CH2=CH-COOR2 (2) (wherein R2 is an organic group of 7 to 12 carbon atoms), the mass ratio (1)/(2) of said acrylic acid ester (1) to said acrylic acid ester (2) being 65/35 to 20/80.