UV-Curable Silicone Adhesive Composition for Temporary Fixing
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Solution Overview
Problem
Existing silicone pressure-sensitive adhesive (PSA) compositions face issues with shrinkage upon cooling, dimensional errors, adhesive migration, and insufficient strength during micro-transfer-printing, particularly in UV-curable types lacking a resin component.
Innovation Solution
A UV-curable silicone PSA composition using an organopolysiloxane with specific (meth)acryloyloxy-containing groups and a siloxane-free monofunctional (meth)acrylate compound, along with a photopolymerization initiator, to achieve rapid curing with excellent adhesion and rubber strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat cure type silicone PSA compositions are used, then adhesive properties are achieved, but the cured product shrinks upon cooling resulting in increased dimensional errors
Solution Approach 1:
The patent changes the curing mechanism from thermal curing to UV photopolymerization curing. This parameter change eliminates the thermal expansion and contraction cycle that causes shrinkage and dimensional errors, while maintaining the adhesive properties through photopolymerization crosslinking of the silicone PSA composition.
Solution Approach 2:
The patent replaces the thermal curing mechanism (heat treatment) with a photopolymerization mechanism (UV irradiation). This substitution eliminates the need for heating and subsequent cooling that causes thermal shrinkage, thereby maintaining dimensional accuracy while achieving cure and adhesive properties.
2Reliability
If solid resin component is added as tackifier, then adhesive properties are improved, but uncrosslinked resin component causes adhesive migration and is left on chips or parts
Solution Approach 1:
The patent removes the solid resin component (tackifier) from the silicone PSA composition. By extracting this component that causes adhesive migration, the patent eliminates the harmful effect of resin being left on chips or parts, while maintaining adhesive properties through the photopolymerization-cured silicone network.
Solution Approach 2:
The patent changes the adhesive mechanism from relying on solid resin tackifiers to relying on photopolymerization-crosslinked silicone. This parameter change eliminates the migration issue associated with uncrosslinked resin components while maintaining pressure-sensitive adhesion through the cured silicone network.
3Reliability
If conventional silicone PSA compositions are used, then adhesive properties are achieved, but the material is insufficient in strength and undergoes cohesive failure upon molding and transferring
Solution Approach 1:
The patent creates a composite material system combining silicone PSA composition with photopolymerization initiator and (meth)acrylate monomers. This composite structure provides both adhesive properties from the silicone PSA and cohesive strength from the crosslinked polymer network, preventing cohesive failure during molding and transferring.
Solution Approach 2:
The patent changes the curing mechanism to photopolymerization, which creates a crosslinked polymer network that significantly enhances cohesive strength. This parameter change prevents cohesive failure during molding and transferring operations while maintaining the adhesive properties of the silicone PSA composition.
4Loss of time
If UV irradiation is used for curing, then curing time is reduced and dimensional accuracy is improved, but adhesive force and rubber strength are insufficient without resin component
Solution Approach 1:
The patent optimizes the composition parameters by incorporating specific ratios of (meth)acrylate monomers and photopolymerization initiators into the silicone PSA system. This parameter optimization enables complete photopolymerization crosslinking that provides sufficient adhesive force and rubber strength, eliminating the insufficiency issue while maintaining rapid UV curing and dimensional accuracy.
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 cures quickly and effectively, providing a cured product with superior pressure-sensitive adhesion and rubber strength, suitable for temporary adhesion and fixing materials, while preventing adhesive migration and cohesive failure.
Implementation Method 1
a UV-curable silicone PSA composition comprising (A) 100 parts by weight of an organopolysiloxane having the general formula (1), (B) 1 to 200 parts by weight of a monofunctional (meth)acrylate compound free of a siloxane structure, and (C) 0.01 to 20 parts by weight of a photopolymerization initiator
Data Source
Figure 1~3
AI summary
This UV curable silicone composition contains (A) an organopolysiloxane represented by general formula (1) [R1 represents a monovalent hydrocarbon group having 1-20 carbon atoms, R2 represents an aromatic group, X represents a group represented by formula (2), a, m, and n respectively represent numbers in the ranges of 1 ≤ a ≤ 3, 1 ≤ m ≤ 2,000, 1 ≤ n ≤ 2,000, and m/(n+m) ≥ 0.01 is satisfied. (R1 is as defined above. R3 represents an oxygen atom or an alkylene group having 1-20 carbon atoms, R4 represents an acryloyloxyalkyl group, a methacryloyloxyalkyl group, an acryloyloxyalkyloxy group, or a methacryloyloxyalkyloxy group, p represents a number in the range of 0 ≤ p ≤ 10, and c represents a number in the range of 1 ≤ c ≤ 3.)], (B) a mono-functional (meth)acrylate compound not containing a siloxane structure, and (C) a photopolymerization initiator, and provides, as a temporary fixing material, a cured product having excellent adhesiveness and rubber strength.