Polyester Composition Low Temperature Impact Resistance
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Solution Overview
Problem
Photovoltaic junction boxes require materials with low temperature impact resistance to withstand extreme temperatures without structural damage, which existing polyester compositions fail to provide effectively.
Innovation Solution
Compositions comprising 30-65 weight percent polyester, 7-25 weight percent ethylene copolymer toughener, 5-25 weight percent copolyether ester elastomer with shore D hardness between 20-50, and optionally a flame retardant, achieving a Gardner impact of at least 4.2 J at -40°C, optimized by specific weight ratios and the inclusion of halogenated epoxy flame retardants for enhanced impact strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing polyester compositions are used, then the material is simple and easy to manufacture, but the low temperature impact resistance is insufficient
Solution Approach 1:
The patent applies composite materials by combining polyester with two specific elastomeric components (ethylene copolymer and copolyether ester) in defined weight ratios. This multi-material composition resolves the contradiction by achieving superior low temperature impact resistance (Gardner impact ≥4.2 J at -40°C) through the synergistic effect of the composite, while the ratios are optimized to maintain manufacturability.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the weight percentages of each component (polyester: 30-65%, ethylene copolymer: 7-25%, copolyether ester: 5-25%) and the ratio between toughening components (0.3-2.5). These parameter optimizations enable the composition to achieve the required Gardner impact of at least 4.2 J at -40°C while maintaining practical manufacturability.
2Strength
If more elastomeric components are added to improve impact resistance, then the impact strength increases, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent optimizes the weight ratios of elastomeric components to achieve the minimum required Gardner impact of 4.2 J at -40°C. By setting specific ranges (ethylene copolymer: 7-25%, copolyether ester: 5-25%) and their ratio to each other (0.3-2.5), the formulation achieves adequate impact strength without excessive addition of expensive elastomers, balancing performance with manufacturing economy.
Solution Approach 2:
The use of a composite system with two complementary elastomeric components allows each to contribute differently to impact resistance. The ethylene copolymer provides baseline toughness while the copolyether ester enhances low-temperature performance, achieving the required 4.2 J Gardner impact at optimized loadings that balance cost and performance.
3Strength
If the composition is optimized for maximum impact resistance, then the Gardner impact increases, but the formulation complexity and component selection difficulty increase
Solution Approach 1:
The patent establishes specific parameter ranges and ratios to achieve maximum Gardner impact while controlling formulation complexity. The weight percent ranges (polyester: 30-65%, ethylene copolymer: 7-25%, copolyether ester: 5-25%) and the inter-component ratio (0.3-2.5) provide clear formulation guidelines that lead to optimized impact performance without requiring overly complex formulation processes.
Data Source
AI summary
Compositions comprising: (a) 30 to 65 weight percent of a polyester;(b) 7 to 25 weight percent of an ethylene copolymer toughener; (c) 5 to 25 weight percent of a copolyether ester elastomer having a shore D hardness of 20 to 50; optionally (d) 15 to 35 weight percent of a halogenated epoxy flame retardant; and (e) when (d) is present in the composition, optionally, 2 to 10 weight percent of a flame retardant synergist;wherein: the ratio of the combined weight of (b)+(c) relative to the weight of (a) ranges from 0.40 to 0.85; the ratio of the weight of (b) relative to that of (c) ranges from 0.3 to 2.5; and the Gardner impact of the composition, when molded, is at least 4.2 J, measured at −40° C. according to ASTM D5420. Methods of making articles by molding these melt-mixed compositions.