Polyester-Epoxide Polymer Compositions for Flexible Adhesives
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Solution Overview
Problem
The challenge in the epoxy-based products industry is to achieve desirable flexibility at a low cost while maintaining other important properties, such as high glass-transition temperatures and low ultimate elongations, without using expensive polyisocyanates or environmentally challenging polyamine curatives.
Innovation Solution
The development of polyester-epoxide polymer (PEEP) compositions, which involve a reaction product of a polyepoxide compound and a polyester polyol with specific hydroxyl and epoxy equivalent ratios, allowing for the creation of adhesives, coatings, and elastomers with enhanced flexibility and properties, using commercially available materials and conventional processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional epoxy resins are used with polyamines or polyisocyanates to achieve high crosslinking density, then strength and chemical resistance are improved, but flexibility deteriorates and cost increases
Solution Approach 1:
The patent changes the chemical parameters of the curing system by using polyester polyols with specific hydroxyl functionality (2-6) and hydroxyl value (50-400 mg KOH/g) instead of conventional polyamines or polyisocyanates. This parameter change maintains adequate crosslinking density while improving flexibility and reducing cost.
Solution Approach 2:
The patent creates a composite curing system combining polyester polyol with epoxidized oils (linseed, soybean, or tung oil) to achieve a balance between crosslinking density and flexibility. The composite material approach allows simultaneous achievement of strength and flexibility that neither component could provide alone.
2Strength
If polyester polyols with high hydroxyl functionality (>4) or high hydroxyl number (>500 mg KOH/g) are used to react with epoxy resins, then crosslinking density is improved, but flexibility deteriorates
Solution Approach 1:
The patent optimizes the hydroxyl functionality parameter to a moderate range of 2-6 and hydroxyl value to 50-400 mg KOH/g, avoiding the extremes of high functionality (>4) and high hydroxyl number (>500). This parameter optimization achieves adequate crosslinking while preserving flexibility.
3Ease of operation
If polyisocyanates are used to achieve high performance properties, then strength and flexibility are improved, but cost increases and special handling requirements arise
Solution Approach 1:
The patent replaces expensive polyisocyanates with more economical polyester polyols that do not require special handling or storage conditions. The polyester polyol achieves adequate flexibility without the high cost and handling requirements of polyisocyanates.
4Strength
If polyamines are used to cure epoxy resins, then crosslinking density is improved, but environmental concerns and handling challenges arise
Solution Approach 1:
The patent converts the typically harmful polyamine curing system into an environmentally benign polyester polyol system. The polyester polyol maintains adequate crosslinking density while eliminating the environmental and health concerns associated with polyamine emissions and handling.
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 PEEP compositions exhibit increased elongation, reduced glass-transition temperatures, and a favorable balance of properties, eliminating the need for polyisocyanates and polyamines, thus offering a cost-effective and environmentally friendly solution for epoxy-based products.
Implementation Method 1
The PEEP composition comprises a reaction product of a polyepoxide compound and a polyol composition
Data Source
AI summary
Polyester-epoxide polymer (PEEP) compositions are disclosed. The PEEP compositions comprise a reaction product of a polyepoxide compound (eq. wt. 125 to 250 g/eq.) and a polyester polyol composition. The ratio of epoxy equivalents to hydroxyl equivalents is within the range of 0.8 to 3.5. The PEEP composition has a Tg within the range of -40°C to 60°C. Elevated temperature-cure and low temperature-cure processes for making the PEEP compositions are also disclosed. In a simple yet innovative approach, a new class of polymers useful for adhesives, coatings, elastomers, and other valuable products is assembled from readily available starting materials without reliance on polyisocyanates or polyamines. The PEEP compositions have increased elongation and lower Tg when compared with traditional epoxy products.