Solvent-Free Adhesive Composition for High-Temperature Lamination
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Solution Overview
Problem
Solvent-free laminate adhesives face challenges with low laminate strength and short pot life, particularly when stored at high temperatures, due to the reaction of styrene-maleic anhydride copolymer with polyol components, leading to increased viscosity and insufficient adhesion to aluminum materials after high-temperature retort treatments.
Innovation Solution
A solvent-free adhesive composition using a polyisocyanate and aromatic vinyl-maleic anhydride copolymer with a specific molar ratio, which improves laminate strength and maintains pot life even after long-term storage, including high-temperature conditions, by enhancing compatibility and reducing the need for toxic compatibilizers like propylene carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the molecular weight of the resin component is increased to improve laminate adhesion strength, then the laminate strength is improved, but the pot life becomes insufficient
Solution Approach 1:
The patent changes the molecular weight parameter of the polyol component to an optimal range (500-5000) to achieve both sufficient pot life and laminate strength. It also adjusts the equivalent ratio of isocyanate groups to hydroxyl groups (1.0-5.0) to balance reactivity and working time, resolving the trade-off between strength and pot life through parameter optimization
Solution Approach 2:
The patent creates a composite adhesive system combining polyisocyanate, polyol, and aromatic vinyl-maleic anhydride copolymer. This composite formulation achieves synergistic effects where the copolymer enhances adhesion to aluminum materials while the polyol provides flexibility and pot life, overcoming the limitations of single-component systems
2Duration of action of stationary object
If the adhesive is stored at high temperature for long time, then the availability is improved, but the viscosity increases significantly due to reaction between styrene-maleic anhydride copolymer and polyol
Solution Approach 1:
The patent extracts the problematic styrene-maleic anhydride copolymer from the adhesive formulation and replaces it with aromatic vinyl-maleic anhydride copolymer. This removal of the harmful component (styrene-based copolymer that reacts with polyol at high temperatures) eliminates the viscosity increase issue during storage while maintaining adhesion performance
Solution Approach 2:
The patent eliminates the need for propylene carbonate compatibilizer by using the aromatic vinyl-maleic anhydride copolymer system, which maintains stability without additional additives. This simplifies the formulation and removes a component that could contribute to viscosity changes during storage
3Ease of operation
If propylene carbonate is added as a blended component to improve coating property, then the coating property is improved, but toxic compounds may elute into food content
Solution Approach 1:
The patent removes propylene carbonate from the adhesive formulation entirely, replacing it with a solvent-free system based on polyisocyanate and polyol. This extraction of the harmful low-molecular-weight solvent eliminates the risk of toxic compound elution into food contents while maintaining appropriate coating properties through the polymer composition itself
Solution Approach 2:
The patent creates an inert, food-safe adhesive system that does not rely on potentially harmful solvents. The solvent-free formulation using reactive polymers provides a safe barrier between the adhesive and food content, eliminating the need for propylene carbonate that could migrate into packaged food
4Ease of operation
If the adhesive uses low molecular weight resin to obtain appropriate coating property, then the coating property is improved, but the adhesion strength to aluminum base materials in high-temperature environment is insufficient
Solution Approach 1:
The patent formulates a composite adhesive system combining polyisocyanate, polyol, and aromatic vinyl-maleic anhydride copolymer. This composite provides both the low viscosity needed for good coating properties and the chemical composition required for strong adhesion to aluminum materials in high-temperature environments, achieving both requirements simultaneously
Solution Approach 2:
The patent optimizes the molecular weight of the polyol component (500-5000) and the equivalent ratio of isocyanate to hydroxyl groups (1.0-5.0) to achieve the right balance between coating fluidity and adhesion strength. These parameter adjustments allow the adhesive to wet the surface properly while maintaining sufficient bonding strength after curing
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 exhibits excellent laminate strength and extended pot life, maintaining performance after storage and high-temperature treatments, while minimizing the elution of toxic compounds, thus suitable for packaging materials like food pouches.
Implementation Method 1
a polyisocyanate/polyol curing-type solvent-free adhesive
Implementation Method 2
the organic solvent is evaporated as the film passes through an oven
Data Source
AI summary
Provided are a solvent-free-adhesive polyisocyanate composition, containing, as essential components, a polyisocyanate (A) and an aromatic vinyl-maleic anhydride copolymer (B), which is a copolymer of aromatic vinyl and maleic anhydride and in which a molar ratio [aromatic vinyl/maleic anhydride] of raw material monomers of the copolymer is 1.5/1 to 5/1, and a method for producing the polyisocyanate composition; a solvent-free adhesive containing, as essential components, the solvent-free-adhesive polyisocyanate composition and a polyol (Y); and a multilayer film obtained by laminating a first base material film, a second base material film, and an adhesive layer between the base material films, in which the adhesive layer is formed of the solvent-free adhesive.