Unsaturated Polyester Resin Osmotic Blister Resistance
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Solution Overview
Problem
Existing unsaturated polyester resins struggle to achieve good osmotic blister resistance while maintaining UV weathering properties and styrene solubility, as high aromatic content leads to accelerated gloss loss and yellowing under UV exposure, and substituting aliphatic dicarboxylic acids compromises osmotic blister resistance and polymer solubility.
Innovation Solution
A class of unsaturated polyester resins comprising diacid residues from 1,4-cyclohexanedicarboxylic acid, 1,2-hexahydrophthalic acid, isophthalic acid, terephthalic acid, and phthalic acid, with 2-butenedioic acid, and diol residues from 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,2-propanediol, with specific molecular weight and viscosity ranges, which are copolymerized with ethylenically unsaturated monomers to form coatings and molded articles with improved osmotic blister resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aromatic diacids such as isophthalic acid are incorporated into the unsaturated polyester resin gel coat to achieve good osmotic blister resistance, then osmotic blister resistance is improved, but UV weathering properties deteriorate due to accelerated gloss loss and yellowing upon UV exposure
Solution Approach 1:
The patent changes the chemical structure parameters of the diacid component by using cycloaliphatic diacids (1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-hexahydrophthalic acid) instead of aromatic diacids. This structural parameter change maintains osmotic blister resistance while eliminating the UV absorption characteristics that cause gloss loss and yellowing.
Solution Approach 2:
The patent creates a composite diacid system combining cycloaliphatic diacids with unsaturated diacids (itaconic acid, mesaconic acid, tigonic acid) in specific ratios. This composite approach allows the cycloaliphatic portion to provide osmotic blister resistance while the unsaturated portion contributes to UV weathering resistance, achieving both properties simultaneously.
2Object-affected harmful factors
If aliphatic dicarboxylic acids are substituted for isophthalic acid to improve UV weathering, then UV weathering is improved, but osmotic blister resistance deteriorates and polymer solubility in styrene becomes poor
Solution Approach 1:
The patent modifies the diacid structure by introducing cycloaliphatic rings with specific cyclic structures (cyclohexane rings in 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid). This structural parameter change provides both the UV weathering resistance of aliphatic structures and the osmotic blister resistance associated with aromatic structures, while maintaining styrene solubility.
3Reliability
If 2,2,4,4-tetramethyl-1,3-cyclobutanediol is used in the unsaturated polyester resin to improve osmotic blister resistance, then osmotic blister resistance is enhanced, but decomposition of the diol occurs during processing at elevated temperatures
Solution Approach 1:
The patent introduces 1,2-propanediol as an intermediary component in the diol system. This diol acts as a stabilizing agent that protects 2,2,4,4-tetramethyl-1,3-cyclobutanediol from decomposition during processing. The 1,2-propanediol preferentially reacts or forms a protective matrix that prevents thermal degradation of the cyclobutanediol structure.
Solution Approach 2:
The patent creates a composite diol system combining 2,2,4,4-tetramethyl-1,3-cyclobutanediol (20-90 mol%) with 1,2-propanediol (80-20 mol%). This composite approach allows the cyclobutanediol to provide osmotic blister resistance while the propanediol component stabilizes the system against thermal decomposition during processing.
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 solution provides unsaturated polyester resins with enhanced osmotic blister resistance, maintaining good styrene solubility and UV weathering properties, suitable for applications in coatings and molded articles exposed to organic or aqueous liquids, such as boat hulls and sanitary ware, with reduced decomposition of 2,2,4,4-tetramethyl-1,3-cyclobutanediol during processing.
Implementation Method 1
The unsaturated polyester resin is typically dissolved in and copolymerized with a ethylenically unsaturated monomer, i.e., styrene, to form the final cured resin
Data Source
AI summary
Disclosed are unsaturated polyester resins comprising residues of 1,2-propanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, an aliphatic, cycloaliphatic, or aromatic diacid, and 2-butenedioic acid. Also disclosed are curable compositions containing admixtures of the unsaturated polyesters and aromatic vinyl compounds copolymerizable with the unsaturated polyesters, and coatings and casted and molded articles obtained from the curable compositions. The curable compositions are useful for coatings and casted and molded articles that have at least one surface that is persistently exposed to organic or aqueous liquids.