Acrylic PSA Composition for Mobile Electronics Adhesion
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Solution Overview
Problem
Pressure-sensitive adhesive (PSA) sheets used in mobile electronics face challenges in achieving both light-pressure initial adhesion and deformation resistance to continuous z-axial loads, particularly in small bonding areas with flexible parts like flexible printed circuits, where current solutions either compromise on adhesion strength or require high-temperature thermal press-bonding.
Innovation Solution
An acrylic PSA composition comprising a high molecular weight acrylic polymer with a weight average molecular weight greater than 70×10^4 and a dispersity below 15, combined with tackifier resins and (meth)acrylic oligomers, which provides excellent light-pressure initial adhesion and deformation resistance without the need for high-temperature thermal press-bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the degree of crosslinking in PSA is increased to improve cohesive strength, then deformation resistance is improved, but initial adhesive strength decreases
Solution Approach 1:
The invention changes the molecular weight parameter of the acrylic polymer to greater than 70×10^4 and controls dispersity (Mw/Mn) to 15 or less. This parameter change allows the polymer to achieve both high cohesive strength through entanglement and high initial adhesive strength through sufficient chain ends, resolving the contradiction between crosslinking degree and adhesion performance
Solution Approach 2:
The invention creates a composite adhesive system combining high molecular weight acrylic polymer (Mw>70×10^4) with specific additives including silane crosslinking agents and zinc borate. This composite approach allows the base polymer to provide adhesion while the crosslinking agents provide cohesive strength without sacrificing initial adhesive performance
2Strength
If high-temperature thermal press-bonding is used to achieve deformation resistance, then bonding strength is improved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The high molecular weight acrylic polymer (Mw>70×10^4) with controlled dispersity provides self-reinforcing properties through molecular entanglement and potential self-crosslinking mechanisms. The material inherently resists deformation under continuous z-axial load without requiring external high-temperature processing, enabling self-service deformation resistance
Solution Approach 2:
The invention replaces the mechanical/thermal press-bonding system with a chemically-based adhesion system. The acrylic polymer composition achieves bonding strength through molecular-level adhesion and cohesive strength through entanglement and crosslinking, substituting the need for high-temperature mechanical pressing equipment
3Reliability
If the degree of crosslinking is lowered to improve initial adhesive strength, then light-pressure adhesion is improved, but deformation resistance decreases
Solution Approach 1:
The invention changes the molecular weight parameter to greater than 70×10^4 and controls dispersity (Mw/Mn) to 15 or less. This creates a polymer with sufficient chain ends for adhesion while maintaining entanglement density for deformation resistance, eliminating the need to lower crosslinking degree
Solution Approach 2:
The invention uses a composite system where the high molecular weight acrylic polymer provides both adhesion and structural integrity, supplemented by crosslinking agents (silane-based) and zinc borate. This composite structure allows low crosslinking degree to maintain adhesion while the polymer matrix provides deformation resistance
Data Source
AI summary
The present invention provides an acrylic PSA composition. The acrylic PSA composition comprises an acrylic polymer as its base polymer and at least one species selected among tackifier resins and (meth)acrylic oligomers. The acrylic polymer has a weight average molecular weight higher than 70×104. The acrylic polymer has a dispersity (Mw/Mn) below 15.