Aliphatic Polyurethane Adhesive UV Yellowing
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Solution Overview
Problem
Two-component-curing laminating adhesives used for outdoor composite sheets suffer from yellowing due to solar ultraviolet radiation and delamination caused by rainwater, sunlight irradiation heat, and ultraviolet rays, leading to adhesive deterioration.
Innovation Solution
A laminating adhesive comprising a polyisocyanate component without aromatic derivatives and a polyol component with a cyclohexane ring, specifically a crystalline polyurethane polyol obtained from a crystalline polycarbonate diol, which suppresses yellowing and maintains adhesion performance under outdoor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a two component-type polyurethane adhesive containing aromatic rings is used for outdoor composite sheets, then adhesion performance is improved, but yellowing occurs due to solar ultraviolet radiation and delamination is caused by rainwater and heat
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by using aliphatic polyisocyanates instead of aromatic ones, and incorporating crystalline polycarbonate diols with specific molecular weights. This parameter change eliminates the yellowing issue while maintaining adhesion performance, resolving the contradiction between strength and outdoor durability
Solution Approach 2:
The patent creates a composite adhesive system combining specific polyisocyanate components with polyol components containing crystalline polycarbonate diols. This composite material approach achieves both excellent adhesion and resistance to UV radiation, rainwater, and heat, simultaneously satisfying both requirements
2Strength
If aromatic polyisocyanates are used to achieve strong adhesion, then bonding strength is improved, but the adhesive deteriorates under ultraviolet rays and heat causing delamination
Solution Approach 1:
The patent changes the chemical structure parameter from aromatic to aliphatic polyisocyanates, which fundamentally alters the UV resistance properties while maintaining bonding strength. This parameter substitution resolves the contradiction by eliminating the harmful effect of aromatic rings under UV exposure
Solution Approach 2:
The patent replaces the unstable aromatic polyisocyanate system with a more stable aliphatic system that resists degradation. This substitution creates a long-lasting adhesive that maintains its bonding properties under outdoor conditions, effectively replacing the short-lived aromatic-based adhesive
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 adhesive prevents yellowing and delamination, ensuring excellent durability and adhesion performance under rainwater, sunlight, and ultraviolet exposure, making it suitable for outdoor composite sheets.
Implementation Method 1
a macropolyol (B1) that does not contain an aromatic ring but contains a cyclohexane ring, which macropolyol (B1) is a polyurethane polyol (B1-1') obtained by reaction of a crystalline polyol (B1-1a') that does not contain an aromatic ring and is crystalline at normal temperature with a polyisocyanate (B1-1b)
Data Source
AI summary
[Solution to Problem] The laminating adhesive of the present invention includes a polyisocyanate component (A) and a polyol component (B), wherein the polyisocyanate component (A) contains a polyisocyanate (A1) that does not contain an aromatic ring, and the polyol component (B) contains a macropolyol (B1) that does not contain an aromatic ring but contains a cyclohexane ring.