Organopolysiloxane PSA Composition for Low-Temperature Modulus
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Solution Overview
Problem
Existing polysiloxane pressure sensitive adhesive compositions do not adequately satisfy the requirements of high storage elastic modulus (G') in a wide temperature range, including low temperatures, sufficient adhesion, and rapid curability for practical use, particularly in advanced electronic materials and display devices.
Innovation Solution
A hydrosilylation reaction-curable organopolysiloxane composition is formulated with specific ratios of organopolysiloxane resins having different molecular weights and limited hydroxyl and hydrolyzable groups, combined with an organohydrogenpolysiloxane and a hydrosilylation reaction catalyst, to achieve a shear storage elastic modulus of 0.77 to 50.00 MPa at -20°C and sufficient adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysiloxane pressure sensitive adhesive compositions are used to achieve heat resistance and electrical insulating properties, then adhesion to various adherends and thermal stability are improved, but storage elastic modulus in low temperature regions and curability are insufficient
Solution Approach 1:
The invention changes the chemical composition parameters by incorporating specific ratios of vinyl-containing polysiloxane (0.01-5 mass% vinyl groups), hydroxyl-containing polysiloxane (3-20 mass% hydroxyl groups), and controlled amounts of crosslinking agents. This parameter optimization enables the adhesive to maintain storage elastic modulus above 0.77 MPa at -20°C while preserving heat resistance and electrical insulating properties.
Solution Approach 2:
The invention creates a composite polysiloxane system combining multiple polymer components with different functions: vinyl-containing polysiloxane for base adhesive properties, hydroxyl-containing polysiloxane for crosslinking reactivity, and organometallic catalysts for curing acceleration. This composite structure achieves simultaneous improvement in low-temperature elasticity, heat resistance, and curability.
2Temperature
If polysiloxane pressure sensitive adhesive compositions are formulated for heat resistance, then thermal stability is improved, but curability and adhesion for practical use are not sufficient
Solution Approach 1:
The invention introduces organometallic catalysts (platinum complexes, organotin compounds, or organic metal complexes) as intermediaries to accelerate the crosslinking reaction between vinyl groups and hydroxyl groups. These catalysts enable rapid curing at practical temperatures while maintaining the heat resistance of the polysiloxane matrix, resolving the contradiction between thermal stability and curability.
Solution Approach 2:
The invention optimizes the concentration of reactive functional groups (vinyl and hydroxyl) and catalyst content to achieve practical curability. By controlling vinyl content at 0.01-5 mass% and hydroxyl content at 3-20 mass%, combined with appropriate catalyst loading, the system achieves sufficient crosslinking density for practical use while preserving heat resistance.
3Strength
If polysiloxane pressure sensitive adhesive compositions are designed for adhesion, then bonding strength is improved, but storage elastic modulus in wide temperature regions including low temperatures is insufficient
Solution Approach 1:
The invention carefully balances the ratio of adhesive components to achieve optimal adhesion while maintaining low-temperature elasticity. By controlling the hydroxyl group content (3-20 mass%) for adhesion and combining with vinyl-containing polysiloxane (0.01-5 mass% vinyl), the system achieves strong bonding without sacrificing storage elastic modulus at -20°C, resolving the contradiction between adhesion strength and low-temperature mechanical properties.
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 forms a pressure sensitive adhesive layer with excellent curability, high adhesion, and designed elastic modulus, suitable for use in electronic materials and display devices, addressing issues of poor adhesion and viscoelasticity at low temperatures.
Implementation Method 1
A hydrosilylation reaction-curable organopolysiloxane composition is formulated with specific ratios of organopolysiloxane resins having different molecular weights and limited hydroxyl and hydrolyzable groups, combined with an organohydrogenpolysiloxane and a hydrosilylation reaction catalyst
Data Source
AI summary
A curable organopolysiloxane composition is provided which forms a pressure sensitive adhesive (PSA) layer capable of a wide range of storage elastic modulus (G′) at low temperatures, and with excellent curability and adhesion. A PSA layer-forming organopolysiloxane composition comprises: (A) a chain organopolysiloxane having alkenyl groups; (B) an organopolysiloxane resin which has a content of 9 moles or less of hydroxyl groups and the like and is a mixture of (b1) an organopolysiloxane resin having a weight average molecular weight (Mw) of 4500 or more and (b2) an organopolysiloxane resin having a Mw of less than 4500; (C) an organohydrogenpolysiloxane; and (D) a hydrosilylation reaction catalyst. The mass ratio of component (B) to component (A) is within a range of 0.9 to 3.0, and the shear storage elastic modulus G′ at −20° C. of a PSA layer obtained by curing the composition is within a range of 0.77 to 50.00 MPa.