Acrylic Block Copolymer Adhesive for Low-Temperature Hot-Melt Processing
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Solution Overview
Problem
Existing adhesive compositions, particularly those using acrylic block copolymers, face challenges in hot melt processability and adhesion properties.
Innovation Solution
A hot melt adhesive composition comprising an acrylic block copolymer with specific polymer blocks (A and B) having defined glass transition temperatures and molecular weights, optimized mass ratios of methacrylate and acrylate ester units, and a controlled molecular weight distribution, allowing for low-temperature processing and enhanced adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional acrylic block copolymers are used to improve adhesion properties, then adhesion force is enhanced, but hot melt processability deteriorates due to high melting temperature
Solution Approach 1:
The adhesive composition is segmented into distinct polymer blocks with different functions: a hard segment (polymer block A) providing adhesion force through methacrylate ester units, and a soft segment (polymer block B) enabling low-temperature processing through acrylate ester units. This segmentation allows each block to optimize its properties independently, resolving the contradiction between adhesion strength and melt processability.
Solution Approach 2:
The invention changes the chemical composition parameters of the block copolymer by incorporating specific methacrylate ester units (a1, a2) and acrylate ester units (b1, b2) in controlled ratios. By adjusting the types and proportions of ester units, the glass transition temperatures and melting points of respective blocks are optimized, enabling the adhesive to melt at low temperatures while maintaining strong adhesion.
2Strength
If polymer block A with high methacrylate content is used to improve cohesion force, then adhesion properties are enhanced, but processability worsens due to increased rigidity
Solution Approach 1:
The invention creates a composite block copolymer material where polymer block A (providing cohesion through methacrylate units) is combined with polymer block B (providing flexibility and processability through acrylate units). This composite structure integrates the advantages of both blocks, achieving high cohesion force while maintaining ease of hot melt processing through the complementary soft block.
3Productivity
If low molecular weight copolymer is used to improve flow properties, then hot melt processability is enhanced, but adhesion strength deteriorates
Solution Approach 1:
The copolymer is segmented into blocks with different molecular weight characteristics: block A with higher molecular weight providing adhesion strength, and block B with lower molecular weight contributing to flow properties. This segmentation allows the adhesive to exhibit both strong adhesion and good processability by distributing molecular weight functions across different blocks.
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 composition enables easy hot melt processing at low temperatures and exhibits excellent adhesion force, holding power, and tack, with improved cohesion and flexibility.
Implementation Method 1
the phase separation between the polymer block (A) and the polymer block (B) becomes clearer so that the hot melt adhesive composition that is obtained attains an increase in cohesion force
Implementation Method 2
The adhesive compositions provided by the present invention can be hot-melt processed by being thermally melted at a relatively low temperature (for example, 60 to 140°C)
Data Source
AI summary
The invention provides adhesive compositions which can be hot-melt processed by being thermally melted at a relatively low temperature and which have excellent adhesion force, holding power and tack, and adhesive products including the adhesive compositions. A hot melt adhesive composition includes an acrylic block copolymer (I) including at least one polymer block (A) including methacrylate ester units, and at least one polymer block (B) including acrylate ester units, wherein the methacrylate ester units constituting the polymer block (A) include at least a methyl methacrylate (a1) unit and a methacrylate ester (a2) unit represented by the general formula CH2=C(CH3)-COOR1 (1) wherein R1 is a C2-16 organic group.