Photoreactive Polyester Adhesive Composition for Thermal Stability
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Solution Overview
Problem
Existing solvent-free pressure-sensitive adhesives face issues with thermal stability, such as viscosity increase and gelation, due to the presence of unsaturated groups that react during high-temperature processes, and there is a need for adhesives with improved environmental sustainability.
Innovation Solution
An active energy ray-curable composition containing a polyester with structural units derived from polyvalent carboxylic acid and polyhydric alcohol, and a compound with a photoreactive group, which eliminates the need for unsaturated groups, ensuring excellent thermal stability and adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If unsaturated groups are incorporated into the pressure-sensitive adhesive structure to increase cohesive force, then adhesive strength is improved, but thermal stability deteriorates due to viscosity increase and gelation during hot-melt coating
Solution Approach 1:
The invention extracts and removes the unsaturated groups from the pressure-sensitive adhesive structure. By using a polyester main agent without unsaturated groups (specifically without carboxyl groups that would form unsaturated structures), the patent eliminates the source of thermal instability while maintaining adhesive performance through alternative mechanisms.
Solution Approach 2:
The invention changes the chemical composition parameters of the pressure-sensitive adhesive by selecting specific polyesters with controlled functional groups. The patent specifies using polyesters with hydroxyl groups and carboxyl groups in controlled amounts, and incorporating compounds with specific functional groups (isocyanate, hydroxyl, carboxyl, epoxy) to achieve crosslinking without unsaturated groups, thereby changing the chemical parameters to improve thermal stability.
2Object-generated harmful factors
If solvent-free pressure-sensitive adhesives are used to reduce environmental load, then VOC emissions are reduced, but thermal stability problems occur during high-temperature processing
Solution Approach 1:
The invention creates a composite pressure-sensitive adhesive system by combining a polyester base resin with crosslinking agents containing specific functional groups (isocyanate, hydroxyl, carboxyl, or epoxy groups). This composite structure enables solvent-free formulation for environmental benefits while the crosslinking mechanism provides thermal stability during processing, resolving the contradiction between environmental performance and processing stability.
3Strength
If crosslinkers are added to active energy ray-curable pressure-sensitive adhesives to increase cohesive force, then adhesive strength is improved, but thermal stability deteriorates due to reaction of crosslinker by heating
Solution Approach 1:
The invention extracts and eliminates the need for separate crosslinker components by incorporating crosslinking functionality directly into the polyester structure through controlled inclusion of compounds with specific functional groups. This removes the separate crosslinker that would otherwise react during heating, thereby maintaining thermal stability while achieving the desired cohesive force through in-situ crosslinking.
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 provides excellent active energy ray curability, pressure-sensitive adhesive force, and holding force without the drawbacks of unsaturated groups, making it suitable for solvent-free applications.
Implementation Method 1
active energy ray-curable composition... cured by an active energy ray, such as an ultraviolet ray
Data Source
AI summary
The following is provided as an active energy ray-curable composition having excellent pressure-sensitive adhesive force, holding force, and thermal stability. An active energy ray-curable composition containing a polyester (A) having a structural unit derived from a polyvalent carboxylic acid (α) and a structural unit derived from a polyhydric alcohol (β), wherein the polyester (A) further contains a polyester (A1) having a structural unit derived from a compound (B) having a photoreactive group.