Low-Viscosity Urethane System for High Solids Coating
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Solution Overview
Problem
There is a need for alternative two-component urethane systems that can be coated at high solids levels, as existing systems based on phthalic anhydrides or acids have limitations in achieving high solids content.
Innovation Solution
A two-component urethane system comprising a hydroxy-terminated polyester polyol with specific weight percentages of phthalic acid residues and an aliphatic diol, combined with an isocyanate-terminated prepolymer containing diphenyl methane diisocyanate and a glycol or polyol, which are mixed with solvents to achieve a high solids content coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If existing two-component urethane systems based on phthalic anhydrides or acids are used, then the system can be formulated, but the solids content cannot be coated at high levels
Solution Approach 1:
The patent changes the chemical composition parameters of the polyol component by specifying precise weight percentages (40-75 wt % phthalic acid, 25-60 wt % aliphatic diol) and physical parameters (hydroxyl number 15-60 mg KOH/g, viscosity 50-5000 cP) to enable high solids content coating while maintaining processability
Solution Approach 2:
The patent creates a composite urethane system combining specifically formulated hydroxy-terminated polyester polyol with isocyanate-terminated prepolymer, where the composite composition enables both high solids content and adequate viscosity for coating operations
2Quantity of substance
If high solids content is achieved, then more adhesive material is available, but the viscosity increases making coating difficult
Solution Approach 1:
The patent optimizes the hydroxyl number (15-60 mg KOH/g) and viscosity (50-5000 cP) parameters of the polyol component to maintain adequate flow characteristics even at high solids contents, preventing excessive viscosity buildup
Solution Approach 2:
The patent uses specific local compositional characteristics (aromatic phthalic acid residues providing crosslinking density, aliphatic diol providing flexibility) to achieve high solids content while maintaining localized regions of appropriate viscosity and adhesion properties
3Quantity of substance
If high solids content coating is applied, then substrate bonding is enhanced, but green strength may be compromised
Solution Approach 1:
The patent controls the hydroxyl number and molecular weight characteristics to ensure that at high solids contents, the adhesive maintains sufficient green strength for handling while achieving the desired substrate bonding
Solution Approach 2:
The patent employs a two-component system where the isocyanate-terminated prepolymer acts as a temporary binding agent that provides sufficient green strength during handling, with the final crosslinked network forming after full curing to provide long-term strength
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 system allows for effective bonding of substrates with low viscosity adhesives, maintaining good green strength and adhesion, even at high solids concentrations, making it suitable for packaging and sealing applications.
Implementation Method 1
a two-component urethane system comprising: (a) a hydroxy-terminated polyester polyol comprising polymerized residues of: (i) 40 to 75 wt % of phthalic acid, and (ii) 25 to 60 wt % of an aliphatic diol having Mn from 60 to 150
Implementation Method 2
an isocyanate-terminated prepolymer comprising polymerized residues of: (i) at least one of diphenyl methane diisocyanate (MDI) and toluene diisocyanate (TDI); and (ii) a glycol or polyol having Mn from 90 to 1000
Data Source
AI summary
A two-component urethane system. The first component is a hydroxy-terminated polyester polyol containing polymerized residues of phthalic acid and an aliphatic diol having Mn from 60 to 150, and having no more than 15 wt % polymerized residues of aliphatic acids. The second component is an isocyanate-terminated prepolymer containing polymerized residues of diphenyl methane diisocyanate and/or toluene diisocyanate and a glycol or polyol having Mn from 90 to 1000.