Solvent-Free Adhesive Composition for High-Temperature Sterilization
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Solution Overview
Problem
Solvent-free adhesives used in metal foil laminated composite films for high-temperature sterilization treatments face challenges with rapid curing and reduced adhesive strength due to moisture sensitivity and humidity, leading to poor workability and acid resistance.
Innovation Solution
A method involving the production of an adhesive composition using a trifunctional or higher isocyanate compound and an alcohol-added isocyanate, with specific equivalence ratios and acid values, to create a solvent-free adhesive that maintains workability and exhibits excellent adhesive strength and acid resistance, even under high humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solvent-free adhesive containing a low-molecular weight polyol compound and a polyisocyanate compound is applied under high-temperature conditions, then adhesive strength and acid resistance are improved, but curing reaction rate increases excessively causing rapid viscosity increase and poor workability
Solution Approach 1:
The invention changes the chemical structure parameter of the polyol compound from low-molecular weight to high-molecular weight, which inherently reduces reactivity and slows down the curing reaction rate. This allows the adhesive to maintain good workability during application while still achieving sufficient adhesive strength and acid resistance after curing, resolving the contradiction between strength improvement and workability deterioration.
2Reliability
If acid groups are introduced into the main agent to impart acid resistance to metal foil, then acid resistance is improved, but curing is accelerated excessively causing rapid viscosity increase and poor workability
Solution Approach 1:
The invention changes the molecular weight parameter of the polyol compound to high-molecular weight, which reduces the reactivity of hydroxyl groups. This allows acid groups to be introduced into the polyol structure to provide acid resistance while the high molecular weight prevents excessive curing acceleration, maintaining acceptable workability during application.
3Ease of operation
If secondary or tertiary hydroxyl groups are used to lower reactivity and suppress viscosity increase, then workability is improved, but moisture sensitivity increases causing adhesive strength and acid resistance deterioration under high humidity
Solution Approach 1:
The invention changes the molecular weight parameter to high-molecular weight while maintaining primary hydroxyl groups. The high molecular weight provides sufficient steric hindrance and reduces overall reactivity to prevent excessive curing and maintain workability, while the primary hydroxyl groups ensure adequate reaction with isocyanate groups to achieve required adhesive strength and acid resistance, avoiding the moisture sensitivity problem of secondary/tertiary hydroxyl groups.
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 composition provides resistance to moisture, maintains good workability, and achieves excellent adhesive strength and acid resistance in high-temperature sterilization treatments, improving the durability and performance of metal foil-containing laminated composite films.
Implementation Method 1
a problem arises in that curing is accelerated even further due to the urethanization catalytic effect of the acid groups
Implementation Method 2
The present invention provides an adhesive which, in a metal foil-containing laminated composite film used in a high-temperature sterilization treatment, is resistant to the effects of moisture in the air during curing
Data Source
AI summary
Provided is an adhesive which, in a metal foil-containing laminated composite film used in a high temperature sterilization treatment, is resistant to the effects of moisture in the air during curing, has good workability when used as a solvent-free adhesive, and exhibits excellent adhesive strength and acid resistance. Provided is a method for producing an adhesive composition, the method including: a step of obtaining an alcohol-added isocyanate (E) by reacting a trifunctional or higher isocyanate compound (C2) and a monofunctional alcohol compound (D) at an equivalence ratio of isocyanate groups in the trifunctional or higher isocyanate compound (C2) : monofunctional alcohol (D) = 100 mol% : 25 to 65 mol%, and a step of mixing a polyisocyanate (A) containing a trifunctional or higher polyisocyanate (C1) and the alcohol-added isocyanate (E), and an alcohol (B) having an acid value of 0.5 to 30 mgKOH/g, so that the equivalence ratio between isocyanate groups in the polyisocyanate (A) and hydroxyl groups in the alcohol (B) (isocyanate groups/hydroxyl groups) is within a range from 0.7 to 2.5.