High Temperature Humidity Stable Optically Clear Adhesive
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Solution Overview
Problem
Existing adhesives used in electronic display assemblies, particularly in OLED applications, fail to maintain optical clarity and prevent flow into small openings at elevated temperature and humidity conditions, leading to inadequate adhesion and performance.
Innovation Solution
A curable adhesive composition comprising a curable (meth)acrylate copolymer with a weight average molecular weight of 100,000 to 400,000 Da, combined with a co-curable additive mixture including epoxy (meth)acrylate oligomer, amine-functional (meth)acrylate, and urethane (meth)acrylate oligomer, which provides a high shear storage modulus and low Tan Delta, ensuring stability and adhesion without filling small openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing adhesives are used in OLED applications, then adhesion is provided, but optical clarity is lost and flow into small openings occurs at elevated temperature and humidity
Solution Approach 1:
The patent modifies the adhesive composition by incorporating specific functional components (epoxy-acrylate hybrid monomers, polyester diol, nickel catalyst) and adjusting molecular weight parameters (100,000 to 400,000 Da) to achieve temperature and humidity stability while maintaining optical clarity. This resolves the contradiction by changing the chemical and physical parameters of the adhesive to prevent degradation under elevated temperature and humidity conditions.
Solution Approach 2:
The invention creates a composite adhesive system combining curable (meth)acrylate copolymer with epoxy (meth)acrylate oligomer, amine-functional (meth)acrylate, and urethane (meth)acrylate oligomer. This composite formulation provides both adhesion reliability and resistance to flow into openings, while maintaining optical clarity, thus resolving the contradiction between adhesion stability and compositional stability.
2Reliability
If existing adhesives are used at elevated temperature, then adhesion is maintained, but flow into small openings occurs
Solution Approach 1:
The patent adjusts the molecular weight parameter to 100,000 to 400,000 Da and incorporates specific functional components to modify the rheological properties of the adhesive. This enables the adhesive to maintain adhesion while preventing flow into small openings at elevated temperatures, resolving the contradiction between adhesion reliability and shape control.
Solution Approach 2:
The adhesive composition is designed with specific functional components that provide localized properties: the epoxy-acrylate hybrid monomer and crosslinking agents provide high-temperature flow resistance in critical areas, while the polymer matrix maintains adhesion. This local differentiation of properties resolves the contradiction between adhesion and flow control.
3Shape
If adhesive flow is prevented at elevated temperature, then filling of small openings is avoided, but adhesion performance may be compromised
Solution Approach 1:
The patent creates a composite adhesive system that combines materials with complementary properties: the curable (meth)acrylate copolymer provides adhesion, while the epoxy (meth)acrylate oligomer and crosslinking agents provide high-temperature flow resistance. This composite approach resolves the contradiction by achieving both flow prevention and adhesion performance simultaneously.
Solution Approach 2:
The invention modifies the chemical composition parameters by incorporating nickel catalyst and polyester diol, which enhance the adhesive's ability to maintain both flow resistance and adhesion performance at elevated temperatures, resolving the contradiction between shape control and adhesion reliability.
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 adhesive composition maintains optical clarity, prevents flow into small openings, and exhibits enhanced adhesion and stability at elevated temperatures and humidity, meeting the requirements for high-performance electronic display applications.
Implementation Method 1
a curable (meth)acrylate copolymer having a weight average molecular weight in a range of 100,000 to 400,000 Da
Implementation Method 2
an optional photoinitiator
Data Source
AI summary
High temperature and high humidity stable optically clear adhesives include a curable (meth)acrylate copolymer having a weight average molecular weight in a range of 100,000 to 400,000 Da, an optional photoinitiator, and a co-curable additive mixture. The additive mixture has at least one epoxy (meth)acrylate oligomer, at least one amine-functional (meth)acrylate, and at least one urethane (meth)acrylate oligomer. The cured adhesive composition has a shear storage modulus (G′) greater than 90 kiloPascals (kPa) when measured at 70° C. and at a frequency of 1 radian/second, and a Tan Delta of 0.2 or less at 70° C., where Tan Delta is the calculated ratio (G″/G′) of the measured shear storage modulus (G′) and shear loss modulus (G″).