GLYMO-Free Polyurethane Adhesive for Retort Film Lamination
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Solution Overview
Problem
Existing polyurethane adhesives for flexible packaging materials used in high-temperature food contact and medical retort applications contain 3-glycidyloxypropyltrimethoxysilane (GLYMO), which is potentially genotoxic and requires strict concentration limits, posing challenges in ensuring safety and adhesive strength under demanding conditions.
Innovation Solution
A two-component polyurethane adhesive composition comprising a polyol component made from a reaction mixture of cycloaliphatic, heterocyclic, and linear or branched aliphatic polyols with polyfunctional carboxylic acid, and an isocyanate component with alkoxysilane functionalized isocyanate compounds without epoxide groups, ensuring excellent adhesion and stability without GLYMO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If GLYMO is used as adhesion promoter in polyurethane adhesives, then adhesive strength is improved, but safety compliance deteriorates due to potential genotoxicity
Solution Approach 1:
The patent removes GLYMO (3-glycidyloxypropyltrimethoxysilane) from the adhesive formulation entirely, extracting the harmful substance while maintaining adhesive performance through alternative chemistry based on polyether polyols and polyester polyols with epoxidized natural oils
Solution Approach 2:
The patent changes the chemical parameters of the adhesive system by specifying polyols with particular molecular weight ranges (1000-10000 g/mol), hydroxyl values (50-500 mg KOH/g), and acid values (1-10 mg KOH/g), along with controlled epoxide content (0.1-10 mmol/g) to achieve safe yet effective adhesion
2Object-affected harmful factors
If adhesive formulation is modified to eliminate GLYMO, then safety compliance is improved, but adhesive strength deteriorates
Solution Approach 1:
The patent creates a composite adhesive system combining polyether polyols, polyester polyols, and epoxidized natural oils in specific proportions (each component 10-90 wt%, with the polyether polyol being the major component at 50-90 wt%). This composite approach compensates for removing GLYMO while maintaining bonding strength
Solution Approach 2:
The patent introduces epoxidized natural oils as intermediary substances that provide adhesion promotion functionality previously supplied by GLYMO, acting as a safe alternative mediator between the polyol components and the substrate surfaces
3Temperature
If polyurethane adhesive is used for high-temperature applications, then heat resistance is improved, but adhesive strength deteriorates due to thermal degradation
Solution Approach 1:
The patent incorporates antioxidants and stabilizers into the adhesive formulation before use to cushion against thermal degradation during high-temperature applications such as retorting (121-135°C) and heat sealing, preventing chain scission and crosslinking that would otherwise weaken the 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 composition maintains excellent bonding strength, viscosity, and solvent resistance while adhering to regulatory safety standards by eliminating GLYMO, making it suitable for high-temperature food contact and medical retort applications.
Implementation Method 1
a polyol component and an isocyanate component, wherein the polyol component comprises at least one polyester polyol being a reaction product of at least one cycloaliphatic polyol, at least one heterocyclic polyol, at least one linear or branched aliphatic polyol, and at least one polyfunctional carboxylic acid, and the isocyanate component comprises at least one alkoxysilane functionalized isocyanate compound having no epoxide group
Data Source
AI summary
The present invention relates to a two-component polyurethane adhesive composition for film lamination, in particular in food flexible packaging. Further, the present invention relates to method of manufacturing a laminate by using the two-component polyurethane adhesive composition and the laminate obtainable by the described method.