High-Solids Adhesive Composition via Segmented Polyol System
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Solution Overview
Problem
Conventional solvent-based adhesives face limitations in achieving higher solids content while maintaining good processing characteristics and performance attributes such as low viscosity, long pot life, and enhanced temperature and chemical resistance, which is particularly challenging for applications like food packaging where high performance is required.
Innovation Solution
A two-component adhesive composition comprising an isocyanate component with an isocyanate-terminated prepolymer and a polyol component with polyether polyols, achieving a balanced molecular weight distribution and functionality, allowing for improved processability and performance at higher solids content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solvent-based adhesives use high molecular weight polyester components to achieve good green bond and improved temperature and chemical resistance, then performance is improved, but viscosity increases and processing characteristics deteriorate
Solution Approach 1:
The adhesive system is divided into two separate components: Component A containing the isocyanate-terminated prepolymer and Component B containing the polyol with polyether segments. This segmentation allows each component to be optimized independently - the prepolymer provides performance while the polyol component maintains processability, resolving the contradiction between high performance and low viscosity.
Solution Approach 2:
The invention uses a composite polyol system combining polyester polyol (for performance) and polyether polyol (for processability and low viscosity). This composite material approach allows the adhesive to achieve both good green bond/temperature resistance and acceptable processing characteristics at 50% solids content.
2Ease of operation
If solvent-based adhesives are diluted to 30-40% solids content for better processability, then processing characteristics improve, but solvent content increases requiring removal during lamination
Solution Approach 1:
The invention changes the key parameter of solids content from the conventional 30-40% to 50% or higher, while simultaneously modifying the chemical composition (using polyether-polyester polyol blend) to maintain low viscosity. This parameter change eliminates the need for solvent removal during lamination while preserving good processing characteristics.
3Productivity
If higher solids content (50% or more) is used in solvent-based adhesives, then productivity improves, but viscosity increases and pot life shortens
Solution Approach 1:
The polyol component uses a composite system of polyester polyol and polyether polyol. The polyether segments provide low viscosity and extended pot life, while the polyester segments contribute to adhesion performance. This composite approach enables 50% solids content with acceptable viscosity and pot life, resolving the productivity versus processability contradiction.
Solution Approach 2:
Different segments of the polyol molecule serve different functions: polyether segments provide low viscosity and long pot life for processing, while polyester segments provide adhesion and performance. This local quality differentiation within the polymer structure allows simultaneous achievement of high solids content and good processing characteristics.
4Reliability
If high molecular weight polyester components are used to boost performance, then temperature and chemical resistance improve, but the adhesive must be dissolved in large amounts of solvent for processability
Solution Approach 1:
The invention changes the solids content parameter from conventional 70-80% to 50% or higher, and modifies the polyol composition to include polyether segments that provide low viscosity. This allows the adhesive to achieve high performance with reduced solvent content (50% or more solids) while maintaining processability without requiring excessive solvent for dissolution.
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 enables operation at 50% or more solids content with low viscosity and extended pot life, while providing superior green bond strength, temperature resistance, and chemical resistance, making it suitable for demanding applications like hot fill and retort processes.
Implementation Method 1
a first component comprising an isocyanate and/or a polyurethane prepolymer and a second component comprising one or more polyols
Implementation Method 2
The solvent is evaporated from the applied adhesive composition
Data Source
AI summary
A two-component adhesive composition is disclosed. The adhesive composition comprises an isocyanate component comprising an isocyanate-terminated prepolymer that is the reaction product of a polyisocyanate and an isocyanate reactive component having an average molecular weight greater than 1,000 that comprises a polyester polyol that is the reaction product of a polyhydric alcohol and a polybasic acid. The NCO content of the isocyanate component is, optionally, between 3 and 9%. The isocyanate reactive component comprises a polyester polyol that accounts for 50 wt % or more of the isocyanate reactive component. The composition further comprises a polyol component comprising polyether polyols having an average molecular weight less than 1,500. The composition still further comprises an adhesion promoter. The average functionality of the adhesive composition is from 2 to 2.4. The adhesive composition provides for improved performance and processability. A method for forming a laminate is also disclosed. A laminate formed by this method is also disclosed.