UV-Curable Silicone Adhesive Shape Retention
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Solution Overview
Problem
UV-curable silicone pressure-sensitive adhesive compositions face challenges with shape retention and bonding force, leading to issues with micro-device transfer and limited applicability due to material flow and insufficient bonding strength.
Innovation Solution
A UV cure type silicone pressure-sensitive adhesive composition comprising an organopolysiloxane with (meth)acryloyloxy-containing groups, a monofunctional (meth)acrylate compound, an organopolysiloxane resin, finely divided silica, and a photopolymerization initiator, which provides rapid curing and maintains shape retention with appropriate adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat-cure type solventless silicone base PSAs are used, then the material can be cured completely, but the cured product shrinks during cooling to room temperature causing increased size errors
Solution Approach 1:
The patent transitions from heat-cure to UV-cure mechanism, changing the curing phase from thermal processing to photopolymerization. This eliminates the thermal expansion and subsequent cooling shrinkage cycle, thereby preventing size errors while ensuring complete curing through UV irradiation activation of photoinitiators.
Solution Approach 2:
The patent changes the curing temperature parameter from elevated heat-cure temperatures to room temperature UV curing. By introducing UV-responsive photoinitiators and acrylate-functionalized polysiloxane components, the curing process occurs at ambient conditions, eliminating thermal shrinkage while maintaining cure completeness.
2Manufacturing precision
If the material is coated to a desired pattern, then the coating can be applied precisely, but the material will flow during transportation or with lapse of time so that PSA articles having the desired shape are not obtained
Solution Approach 1:
The patent applies UV irradiation immediately after coating to initiate curing before transportation or time lapse can cause flow. The photopolymerization process starts in advance, rapidly forming a crosslinked network that locks the coating pattern in place and prevents subsequent shape changes.
Solution Approach 2:
The patent replaces reliance on mechanical stability (viscosity alone) with photochemical curing. Instead of depending on the material's resistance to flow under gravity or handling stresses, the system uses UV-induced photopolymerization to chemically fix the coating pattern, substituting chemical action for mechanical stability.
3Productivity
If UV-curable silicone composition is used for rapid curing, then the cure time is reduced, but the bonding force is insufficient and the applicable range is limited
Solution Approach 1:
The patent creates a composite adhesive system combining UV-curable acrylate-functionalized polysiloxane with conventional silicone resin and photoinitiator. This composite formulation integrates the rapid curing capability of UV-reactive components with the proven bonding performance of silicone adhesives, achieving both fast cure and strong bonding force.
Solution Approach 2:
The patent modifies the chemical composition parameters by introducing acrylate functional groups that respond to UV light, enabling rapid photopolymerization. Simultaneously, the formulation maintains appropriate silicone content and resin composition to preserve bonding strength, balancing cure speed and adhesive performance through compositional adjustment.
4Strength
If silicone PSA material with bonding force is utilized, then the transfer capability is achieved, but the shape retention during coating and cure is poor
Solution Approach 1:
The patent applies UV irradiation immediately after coating to initiate curing before the material can flow or lose its shaped form. The photopolymerization process begins in advance, rapidly crosslinking the adhesive in its desired pattern configuration, thereby preserving shape while achieving bonding capability.
Solution Approach 2:
The patent replaces reliance on viscous resistance to shape change with photochemical fixation. Instead of depending on the material's physical resistance to deformation during handling, the system uses UV-induced rapid crosslinking to chemically lock the shaped coating in place, substituting chemical stabilization for mechanical rigidity.
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 ensures good shape retention during coating and curing, achieving satisfactory adhesiveness as a temporary adhesive for micro-device transfer, enhancing the applicability and reliability of the transferred micro-devices.
Implementation Method 1
a photopolymerization initiator, which provides rapid curing and maintains shape retention with appropriate adhesiveness
Data Source
Figure 1~3
AI summary
A composition containing (A) 100 parts of organopolysiloxane having two groups represented by general (R1 represents a monovalent hydrocarbon group having 1-20 carbon atoms, R2 represents an oxygen atom or the like, R3 represents an acryloyloxyalkyl group or the like, p represents a number satisfying 0 ≤ p ≤ 10, and "a" represents a number satisfying 1 ≤ a ≤ 3) per molecule, (B) 1-500 parts of monofunctional (meth)acrylate compound not containing a siloxane structure, (C) 1-5,000 parts of an organopolysiloxane resin containing (a) an R43SiO1/2 unit (in the formula, R4 represents a monovalent hydrocarbon group having 1-10 carbon atoms) and (b) a SiO4/2 unit, where the molar ratio of the unit (a) to the unit (b) is in the range of 0.6 to 1.2:1, (D) 1-100 parts of fine powder silica, and (E) 0.01-20 parts of an optical polymerization initiator. The compound has good shape retention properties and curability for irradiation with ultraviolet light, and provides a cured product which has excellent adhesion suitable for a temporary retention material.