Lactide-Based Polyester Polyols for Low Viscosity Coatings
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Solution Overview
Problem
There is a need for polyester polyols with reduced viscosity, less than 15,000 cps at 25° C., to minimize or eliminate the use of solvents in polyurethane formulations and to achieve low or no VOC emissions while maintaining equivalent or improved physical properties compared to solvent-based systems.
Innovation Solution
Lactide-based random polyester polyols are developed through the reaction of lactide, lactic acid derivatives, polycarboxylic acids, and polyalcohols, with optional components like oxazolidine or ketimine resins, resulting in products with hydroxyl values greater than 400 to 1100 mg KOH/g and low viscosity, enabling the creation of solvent-free or low-VOC polyurethane compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester polyol resins are used to prepare polyurethane coatings, then abrasion resistance and hardness are improved, but viscosity increases to greater than 15,000 cps requiring solvents for handling
Solution Approach 1:
The patent changes the molecular structure parameters of the polyester polyol by using lactide-based polymers with specific hydroxyl values (400-1100 mg KOH/g) and controlled molecular weights, achieving low viscosity (<15,000 cps) while maintaining high functionality for crosslinking and physical property development
Solution Approach 2:
The patent creates composite polyurethane systems by combining lactide-based polyester polyols with polyisocyanates and optional crosslinking agents, achieving a balance between low viscosity for easy handling and high crosslink density for superior abrasion resistance and hardness
2Ease of operation
If solvents are added to reduce viscosity of polyester polyols, then ease of handling is improved, but VOC emissions increase
Solution Approach 1:
The patent fundamentally changes the viscosity parameter through molecular design of lactide-based polyesters with specific hydroxyl values and chain architectures, achieving low viscosity without requiring solvent dilution, thus eliminating VOC emissions while maintaining ease of handling
Solution Approach 2:
The patent extracts and eliminates the solvent component from the polyurethane formulation by developing inherently low-viscosity lactide-based polyester polyols that provide adequate flow and handling properties on their own, achieving solvent-free or low-VOC formulations
3Object-generated harmful factors
If solvent-free polyester polyols are used to reduce VOC emissions, then environmental compliance is improved, but physical properties may deteriorate compared to solvent-based systems
Solution Approach 1:
The patent develops composite polyurethane formulations combining lactide-based polyester polyols with polyisocyanates and crosslinking agents, where the synergistic interaction of components compensates for the absence of solvents, achieving equal or superior physical properties including abrasion resistance, hardness, and chemical resistance
Solution Approach 2:
The patent optimizes the hydroxyl value parameter of the lactide-based polyester polyol (400-1100 mg KOH/g) to control crosslinking density and network structure, ensuring that solvent-free formulations achieve target physical properties through controlled polymer chemistry rather than solvent-mediated processes
Data Source
AI summary
Lactide-based random polyester polyols for use in polyurethane compositions are disclosed. The polyester polyols have an OH value in the range of greater than 400 mg KOH/g up to 1100 mg KOH/g and are the reaction product of at least one polycarboxylic acid, at least one lactide, and one or more polyalcohols. The polyester polyols can be formulated into the B-side of a two part polyurethane composition to obtain a polyurethane having improved hardness and solvent resistance and a low VOC content. The polyurethane composition is particularly suitable for polyurethane coating applications.