Acrylamide Oligomer Additive for High-Temperature PSA Stability
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Solution Overview
Problem
Pressure sensitive adhesives (PSAs) face challenges in maintaining high adhesion and holding strength at elevated temperatures while preventing delamination and creep, especially in the context of modern electronic components with curved surfaces and high thermal cycles.
Innovation Solution
A pressure sensitive adhesive composition incorporating an oligomer additive with a molecular weight range of 20,000 to 1,000,000 g/mol and a glass transition temperature of 70° C. to 115° C., comprising an acrylamide or meth(acrylamide) copolymer and a high glass transition monomer, blended with a base resin to enhance peel creep, anti-lifting, and high-temperature shear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high Tg monomers are introduced to increase high temperature resistance, then delamination resistance is improved, but peeling behavior changes from smooth to shock peeling at high speed peeling rates
Solution Approach 1:
The patent changes the molecular weight parameter of the high Tg polymer from conventional high values (>100,000) to a lower range (2,000-50,000), and adjusts the blending ratio parameter to optimize the balance between high temperature resistance and peeling behavior. This parameter optimization resolves the contradiction by achieving delamination resistance while maintaining smooth peeling at high speeds.
Solution Approach 2:
The patent creates a composite adhesive system by blending lower molecular weight high Tg polymers with base resin and optional tackifiers. This composite approach allows the system to exhibit both the high temperature resistance of high Tg polymers and the smooth peeling characteristics achieved through optimized molecular weight and formulation.
2Strength
If high Ts tackifiers are loaded to improve adhesion, then adhesion is improved, but cohesion deteriorates reducing holding strength and creating aging stability issues
Solution Approach 1:
The patent changes the molecular weight parameter of the high Tg polymer to a lower range (2,000-50,000) which improves compatibility and mixing with the base resin and tackifiers. This parameter change reduces phase separation and migration issues, thereby maintaining cohesion and aging stability while achieving the desired adhesion through optimized formulation.
Solution Approach 2:
The use of lower molecular weight high Tg polymers improves the homogeneity of the adhesive formulation by enhancing miscibility with base resins and tackifiers. This homogeneous mixing prevents segregation, migration, and yellowing during aging, thereby maintaining both adhesion and cohesion over time.
3Strength
If lower molecular weight acrylic polymers are used to achieve desired adhesion, then adhesion performance is improved, but manufacturing complexity increases due to blending requirements
Solution Approach 1:
The patent specifies a particular molecular weight range (2,000-50,000) for the high Tg polymer that optimizes both adhesion performance and blendability. This parameter selection reduces viscosity differences and improves miscibility, thereby simplifying the blending process while achieving the desired adhesion performance.
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 achieves improved adhesion, holding time, and anti-lift properties, with adhesion of at least 11 N/cm on polycarbonate substrates at 70° C. and a holding time of over 10,000 minutes under high-temperature shear tests, while preventing significant peeling distance and lift during static creep tests.
Implementation Method 1
an oligomer additive including (a) one of an acrylamide or meth(acrylamide) copolymer and (b) a high glass transition temperature monomer. The oligomer additive has a molecular weight range of between about 20,000 and about 1,000,000 and a glass transition temperature of between about 70° C. and about 115° C.
Data Source
AI summary
The present application is a composition including abase resin comprising between about 4% and about 15% acrylic acid monomer and an oligomer additive comprising (a) one of an acrylamide or meth(acrylamide) copolymer and (b) a high glass transition temperature monomer. The oligomer additive has a molecular weight range of between about 20,000 and about 1,000,000 and a glass transition temperature of between about 70° C. and about 115° C. The composition has a blending ratio of base resin to oligomer additive of between about 7 to about 30 parts per hundred of resin.