High-Solids Adhesive Composition via Segmented Polyurethane 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, temperature resistance, and chemical resistance, especially in applications like food packaging where high molecular weight polyester components are used.
Innovation Solution
A two-component adhesive composition with a polyester/polyether hybrid system, featuring an isocyanate component and a polyol component, along with an adhesion promoter, that allows for a solids content of 50% or more, achieving balanced molecular weight distribution and functionality, and utilizing solvents like ethyl acetate and methyl ether ketone for improved processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high molecular weight polyester components are used to achieve good green bond and improved temperature and chemical resistance, then performance is improved, but viscosity increases and processability deteriorates
Solution Approach 1:
The adhesive is divided into two separate components: Component A contains the high molecular weight polyester resin providing performance, while Component B contains the polyol and solvent providing processability. This segmentation allows each component to optimize its function without compromise.
Solution Approach 2:
A polyol component acts as an intermediary that reacts with the polyester resin to form a polyurethane adhesive system. The polyol modifies the viscosity and processing characteristics while the polyester provides the performance attributes, allowing both requirements to be met in the final cured adhesive.
2Ease of operation
If solvent-based adhesives are diluted to 30-40% solids content for better processability, then ease of operation is improved, but productivity decreases due to lower line speed
Solution Approach 1:
The adhesive formulation uses a balanced ratio of polyester resin to polyol and solvent, achieving approximately 50% solids content. This parameter optimization provides sufficiently low viscosity for easy processing while maintaining high enough solids content to support productive line speeds without excessive solvent evaporation time.
3Productivity
If high solids content (50% or more) is used in adhesive composition, then productivity is improved, but viscosity increases and pot life shortens
Solution Approach 1:
The adhesive forms a composite polyurethane system through the reaction of polyester resin with polyol components. This composite structure combines the high-performance characteristics of polyester with the viscosity-modifying and pot-life-extending properties of polyols, achieving both high solids content and good processing characteristics.
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 exhibits improved processing characteristics and enhanced performance with high solids content, including low viscosity and extended pot life, while maintaining excellent temperature and chemical resistance, as demonstrated through various testing procedures like boil-in-bag and retort tests.
Implementation Method 1
The two-component adhesive composition comprises an isocyanate component and a polyol component. The components are combined in a predetermined ratio, thereby forming an adhesive composition... The laminate structure is cured to bond the two substrates together.
Implementation Method 2
The adhesive composition, carried in a solvent, is then applied on a film/foil substrate. 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 less than 1,500. The NCO content of the isocyanate component without solvent is between 9 and 18%. The composition further comprises a polyol component comprising a polyester polyol having a molecular weight greater than 1,500 that is the reaction product of a polyhydric alcohol and a polybasic acid. 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 at a solid content greater than 45 wt%. A methods of forming the adhesive composition is also disclosed. A laminate formed by this method is also disclosed.