Organopolysiloxane PSA Composition Low Temperature Modulus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current polysiloxane pressure sensitive adhesive compositions do not adequately meet the requirements of having a low storage elastic modulus, excellent curability, and sufficient adhesion for practical use, especially at low temperatures, in applications such as electronic and display devices.
Innovation Solution
A hydrosilylation reaction-curable organopolysiloxane composition with specific molecular weight and hydroxyl group content, and adjusted mass ratios of organopolysiloxane resin to chain organopolysiloxane, which results in a pressure sensitive adhesive layer with a shear storage elastic modulus of 0.01 to 1.0 MPa at -20°C and sufficient adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polysiloxane pressure sensitive adhesive compositions are used, then heat resistance and electrical insulating properties are achieved, but storage elastic modulus is too high at low temperatures and curability is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific ratios of vinyl-containing organopolysiloxane (0.1-10 mass%), silane-modified polyol (1-20 mass%), and silane-containing isocyanate (0.5-10 mass%). These parameter changes enable the adhesive to achieve both low storage elastic modulus at low temperatures and excellent curability through controlled crosslinking reactions.
Solution Approach 2:
The patent creates a composite adhesive system combining multiple polymer components with complementary functions: vinyl-containing organopolysiloxane provides base adhesive properties, silane-modified polyol contributes to low-temperature flexibility, and silane-containing isocyanate enables crosslinking for curability. This composite approach resolves the contradiction between low-temperature performance and curability.
2Strength
If organopolysiloxane resin with specific molecular weight and hydroxyl group content is used, then adhesion is improved, but storage elastic modulus increases
Solution Approach 1:
The patent optimizes the molecular weight parameter of organopolysiloxane resin to 950-1600 and controls hydroxyl group content within specific ranges. These parameter changes balance adhesion strength and storage elastic modulus by controlling polymer chain length and crosslinking density, achieving both strong adhesion and low-temperature flexibility.
Solution Approach 2:
The patent applies local quality by distributing different functional components throughout the adhesive composition: lower molecular weight segments provide flexibility at low temperatures, while hydroxyl groups localized at specific positions enable adhesion to substrates. This spatial distribution of properties resolves the contradiction between adhesion and low-temperature modulus.
3Temperature
If mass ratio of organopolysiloxane resin to chain organopolysiloxane is adjusted, then storage elastic modulus is reduced, but adhesion decreases
Solution Approach 1:
The patent establishes an optimal mass ratio parameter range of 0.9 to 1.8 between organopolysiloxane resin and chain organopolysiloxane. Within this range, the system achieves both low storage elastic modulus and sufficient adhesion by balancing the flexible chain structures with adhesive functional groups, preventing either property from deteriorating.
Solution Approach 2:
The patent uses partial action by incorporating moderate amounts of low-molecular-weight chain organopolysiloxane (within the 0.9-1.8 mass ratio) rather than excessive amounts. This partial incorporation reduces storage elastic modulus at low temperatures while maintaining enough high-molecular-weight resin to preserve adhesion, avoiding the trade-off extremes.
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 excellent curability and adhesion, providing a pressure sensitive adhesive layer with a low storage elastic modulus suitable for electronic and display device applications, ensuring effective performance across a wide temperature range including low temperatures.
Implementation Method 1
a curable organopolysiloxane composition which forms a pressure sensitive adhesive layer by a hydrosilylation reaction
Data Source
AI summary
A curable organopolysiloxane composition is provided which forms a pressure sensitive adhesive (PSA) layer having a low storage elastic modulus (G′), excellent curability, and sufficient adhesion, along with applications thereof. A PSA layer-forming organopolysiloxane composition comprises: (A) a chain organopolysiloxane having alkenyl groups; (B) an organopolysiloxane resin wherein the weight average molecular weight (Mw) thereof is less than 4500 and the sum of the content of hydroxyl groups, etc. is 9 mole % or less; (C) an organohydrogenpolysiloxane; and (D) a hydrosilylation reaction catalyst; and optionally, (A′) a chain organopolysiloxane which does not contain a carbon-carbon double bond-containing reactive group in the molecule. The mass ratio of the organopolysiloxane resin (B) to the chain organopolysiloxane (A) is within a specific range and the shear storage elastic modulus G′ at −20° C. of a PSA layer obtained by curing the composition is within a range of 0.01 to 1.0 MPa.