Organopolysiloxane PSA Composition for High-Modulus Low-Temp Adhesion
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Solution Overview
Problem
Existing polysiloxane-based pressure-sensitive adhesive compositions do not adequately satisfy the requirements of high shear storage elastic modulus (G′), tensile stress, and curability, especially at low temperatures, for applications in advanced electronics and display elements.
Innovation Solution
A hydrosilylation reaction curable organopolysiloxane composition with specific ratios of hydroxyl and hydrolyzable groups, vinyl content, and molecular weights, forming a pressure-sensitive adhesive layer with a shear storage elastic modulus of 1.0 MPa or more and tensile stress of 0.50 MPa or more at 25°C, using components (A) to (E) to enhance adhesive strength and viscoelasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polysiloxane-based pressure-sensitive adhesive compositions are used, then electrical insulation and heat resistance are improved, but shear storage elastic modulus and tensile stress are insufficient
Solution Approach 1:
The patent changes the molecular weight parameter of the organopolysiloxane resin to 4500 or more (conventionally lower), and controls the sum of hydroxyl groups and hydrolyzable groups to 9 mol% or less. These parameter changes simultaneously achieve high shear storage elastic modulus (1.0 MPa or more) and maintain heat resistance, resolving the contradiction between strength and temperature resistance.
2Object-affected harmful factors
If conventional polysiloxane-based pressure-sensitive adhesive compositions are used, then electrical insulation is improved, but tensile stress is insufficient
Solution Approach 1:
The patent changes the molecular weight parameter to 4500 or more and controls functional group content to achieve tensile stress of 0.50 MPa or more at 500% strain, while maintaining the electrical insulation properties inherent to polysiloxane materials. This resolves the contradiction between electrical insulation and tensile stress.
3Adaptability or versatility
If conventional pressure-sensitive adhesive compositions are used, then adhesion to various adherends is improved, but curability and adhesive strength at low temperatures are insufficient
Solution Approach 1:
The patent changes the molecular weight to 4500 or more and controls the sum of hydroxyl groups and hydrolyzable groups to 9 mol% or less, which provides reliable adhesive strength across a wide temperature range including low temperatures (e.g., -20°C), while maintaining versatility in adhesion to various adherends through the polysiloxane base structure.
4Reliability
If resin component amount is reduced to achieve high molecular weight properties, then curability is improved, but pressure-sensitive adhesive strength becomes insufficient
Solution Approach 1:
The patent optimizes the resin component amount to achieve a mass ratio of organopolysiloxane resin to chain organopolysiloxane of 1.4 to 3.0, which provides both excellent curability through hydrosilylation reaction and sufficient pressure-sensitive adhesive strength, resolving the contradiction between curability and adhesive strength.
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 a pressure-sensitive adhesive layer with excellent curability and adhesive strength, suitable for electronic and display device applications, ensuring reliable adhesion across a wide temperature range including low temperatures.
Implementation Method 1
a hydrosilylation reaction curable organopolysiloxane composition
Data Source
AI summary
Provided is a curing reactive organopolysiloxane composition that forms a pressure-sensitive adhesive layer having practically sufficient curability and pressure-sensitive adhesive strength, and a relatively high shear storage elastic modulus and tensile stress at 500% strain. The organopolysiloxane composition comprises: (A) a chain organopolysiloxane having a content of vinyl portions in alkenyl groups within a range of 0.02 to 0.30 mass %; (B) an organopolysiloxane resin having a content of hydroxyl groups and the like of 9 mol % or less, and a molecular weight of 4500 or more; (C) an organohydrogenpolysiloxane; and (D) a hydrosilylation reaction catalyst. A mass ratio of a resin component to a chain siloxane component is within a range of 1.4 to 3.0. A pressure-sensitive adhesive layer obtained by curing the organopolysiloxane composition has a shear storage elastic modulus G′ at 25° C. of 1.0 MPa or more and a stress at 500% strain of 0.50 MPa or more.