Optically Clear Adhesive Block Copolymer Foldable Screen
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing OCA optically clear pressure sensitive adhesives face challenges in balancing flexibility, tensile properties, and interface adhesion, particularly in applications involving foldable screens where material fatigue and adhesive failure occur.
Innovation Solution
A preparation method using reversible addition fragmentation chain transfer emulsion polymerization to design and prepare block copolymers, resulting in an OCA optically clear pressure sensitive adhesive with high stretchability, transparency, and low haze, while reducing modulus and enhancing peel strength without compromising resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the concentration of photoinitiator is increased to enhance crosslinking density, then the elasticity of OCA is improved, but the tensile properties deteriorate and the material becomes difficult to apply to foldable screens
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific functional monomers (acrylic acid, itaconic acid, maleic acid) with carboxyl groups that can form hydrogen bonds. This chemical parameter change enables the material to achieve both high elasticity and good tensile properties through intermolecular hydrogen bonding networks, rather than relying solely on photoinitiator concentration for crosslinking density.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple components: base monomers (ethyl acrylate, butyl acrylate), functional monomers with carboxyl groups (acrylic acid, itaconic acid, maleic acid), and photoinitiators. This composite formulation allows the material to exhibit both elastic behavior from the polymer network and tensile resistance from hydrogen bonding between carboxyl groups, resolving the contradiction between elasticity and tensile properties.
2Strength
If functional monomers (e.g., acrylic acid) are incorporated to enhance cohesion and improve elasticity, then the peel strength is improved, but the flowability deteriorates and tensile properties remain poor
Solution Approach 1:
The patent optimizes the concentration parameters of functional monomers (acrylic acid, itaconic acid, maleic acid) within specific ranges (0.1-5 wt%, 0.1-3 wt%, 0.1-2 wt% respectively) to balance hydrogen bonding capability with flowability. The controlled parameter ranges ensure sufficient peel strength through hydrogen bonds while maintaining adequate flowability for application to foldable screens.
Solution Approach 2:
The patent introduces local hydrogen bonding sites (carboxyl groups) distributed throughout the polymer matrix. These localized bonding sites provide cohesion and peel strength where needed, while the bulk polymer structure maintains flowability. The carboxyl groups create localized interaction zones that enhance adhesion without compromising overall material flow characteristics.
3Strength
If the modulus of OCA is improved to enhance adhesion strength, then the interface adhesion is improved, but the flexibility deteriorates and the material cannot withstand folding stresses
Solution Approach 1:
The patent modifies the chemical composition by incorporating flexible polymer chains (polyethylene glycol with specific molecular weights: 200, 400, 600, or 800) alongside the adhesive functional groups. This compositional parameter change creates a dual-character material that maintains high adhesion strength through carboxyl group hydrogen bonding while achieving the flexibility needed to withstand folding stresses in foldable screens.
Solution Approach 2:
The patent creates a composite structure combining rigid adhesive components (polymer matrix with carboxyl groups for strong bonding) and flexible components (polyethylene glycol chains). This composite material architecture enables simultaneous achievement of high adhesion strength at the interface and sufficient flexibility to accommodate the mechanical deformation of foldable displays without cracking or delamination.
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 method effectively improves the tensile properties and peel strength of the OCA adhesive, achieving a balance among flexibility, modulus, and interface adhesion, with a recovery rate exceeding 95% and minimal changes in glass transition temperature.
Implementation Method 1
The block copolymers are designed and prepared in a controllable manner by using reversible addition fragmentation chain transfer emulsion polymerization
Implementation Method 2
the ability to reduce refractive index differences by eliminating air gaps, thereby enhancing image clarity
Implementation Method 3
OCA has high flexibility and viscoelasticity, and the ability to reduce refractive index differences by eliminating air gaps
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Disclosed in the present invention are an optically clear pressure sensitive adhesive (OCA) and a preparation method therefor. The optical pressure-sensitive adhesive is composed of one or more block copolymers. In the method, reversible addition fragmentation chain transfer emulsion polymerization is used; by controlling monomer types and the feeding sequence, the block copolymers are designed and prepared in a controllable manner; and one or more prepared block copolymers are mixed, and by means of solution film forming, an optically clear pressure sensitive adhesive (OCA) is prepared. The optically clear pressure sensitive adhesive (OCA) prepared in the present invention has the advantages of high stretchability, high transparency and a low haze, can effectively reduce the modulus and improve the peel strength on the basis that the rebound resilience is not influenced, and has large application prospects in the fields of electronic display apparatuses, wearable electronic apparatuses, resistive touch screens, intelligent optical devices, etc.