Solventless Polyurethane Adhesive Viscosity and Potlife
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Solution Overview
Problem
Conventional solventless polyurethane-based laminating adhesives face challenges with high viscosity and short potlife, limiting their performance in demanding applications like hot fill, boil-in-bag, and retort processes due to the use of aromatic polyester polyols, while polyether-based adhesives offer poor chemical and temperature resistance.
Innovation Solution
A two-component solventless polyurethane adhesive composition comprising an isocyanate component with a polyester polyol as the primary reactive component, blended with a polyether polyol, and a polyol component with a balanced functionality and molecular weight, along with an adhesion promoter, to achieve low application viscosity and extended potlife while enhancing chemical and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic polyester polyols are used to achieve desired thermal and chemical resistance, then thermal and chemical resistance is improved, but viscosity increases and potlife shortens
Solution Approach 1:
The patent changes the chemical composition parameters of the polyol blend, specifically using a ratio of aromatic polyester polyol to aliphatic polyester polyol of from 95:5 to 50:50 and adding polyether polyol in amounts of from 5 to 50 parts by weight per 100 parts by weight of total polyester polyol. This parameter optimization resolves the contradiction by achieving the desired thermal and chemical resistance while maintaining acceptable viscosity and potlife
Solution Approach 2:
The patent creates a composite polyol system by blending aromatic polyester polyol, aliphatic polyester polyol, and polyether polyol. This composite material approach allows the adhesive to combine the thermal and chemical resistance of aromatic polyester polyol with the viscosity benefits of aliphatic polyester polyol and polyether polyol, thereby resolving the technical contradiction
2Ease of operation
If polyether polyols are used to maintain low viscosity and extended potlife, then ease of operation is improved, but chemical and temperature resistance deteriorates
Solution Approach 1:
The patent optimizes the parameter of polyether polyol content to be from 5 to 50 parts by weight per 100 parts by weight of total polyester polyol, and sets the aromatic to aliphatic polyester polyol ratio between 95:5 and 50:50. This balanced parameter selection ensures sufficient polyether content for low viscosity and extended potlife while maintaining enough aromatic polyester content for chemical and temperature resistance
Solution Approach 2:
The patent employs a composite polyol system where polyether polyol provides low viscosity and extended potlife, aromatic polyester polyol provides thermal and chemical resistance, and aliphatic polyester polyol balances the properties. This multi-component composite resolves the contradiction by combining the advantages of different polyol types
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 chemical and thermal resistance, maintaining low viscosity and extended potlife, ensuring strong bond strength and durability even under harsh conditions, as demonstrated by successful boil-in-bag and chemical aging tests.
Implementation Method 1
a two-component solventless polyurethane adhesive composition comprising an isocyanate component and a polyol component
Data Source
AI summary
A two-component solventless adhesive composition is disclosed. The composition comprises an isocyanate component comprising an isocyanate prepolymer that is the reaction product of a polyisocyanate and an isocyanate reactive component comprising at least 40 wt % of a polyester polyol, based upon the dry weight of the isocyanate reactive component, a polyol component having an average functionality between 2.5 and 4.5 and an average molecular weight between 250 and 1,000, and comprising at least 30 wt % of a polyether polyol, based upon the dry weight of the polyol component, and an adhesion promoter. A method for forming laminates comprising the disclosed adhesive compositions is also disclosed.