Polyester Polyol Production Using Organic Phosphites
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Solution Overview
Problem
Current processes for producing polyester polyols from natural raw materials result in products with high acid numbers, leading to undesirable bubble formation, impaired catalysis, and adverse mechanical properties in polyurethanes, as well as severe discoloration, making them unsuitable for industrial-scale use, especially in visually demanding applications.
Innovation Solution
A process involving the use of organic phosphites during the production of polyester polyols from natural carboxylic acids and polyols, which includes heating a reaction mixture containing carboxylic acids, polyhydric alcohols, organic phosphite compounds, and Lewis acids to high temperatures under vacuum, effectively reducing acid numbers and achieving light-colored, high-transparency polyurethanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyester polyols are produced from natural raw materials using conventional polycondensation processes, then the production uses renewable resources and is economically viable, but the products exhibit high acid numbers and severe discoloration
Solution Approach 1:
The patent introduces phosphorous compounds as intermediary substances that mediate the polycondensation reaction. These phosphorous compounds act as catalysts and stabilizers during the reaction process, enabling the conversion of natural raw materials into polyester polyols with low acid numbers and light color, thus resolving the quality issues while maintaining the use of renewable resources
Solution Approach 2:
The patent changes the chemical parameters of the polycondensation process by introducing phosphorous compounds as catalysts and stabilizers. This parameter change enables the reaction to proceed under controlled conditions that produce polyester polyols with improved acid numbers and color characteristics, transforming the product quality without changing the fundamental use of natural raw materials
2Productivity
If high temperatures are used to accelerate polycondensation reactions, then reaction speed increases, but bubble formation and mechanical property degradation occur
Solution Approach 1:
Phosphorous compounds serve as intermediary catalysts that lower the activation energy barrier of the polycondensation reaction. This allows the reaction to proceed at moderate temperatures with high speed, eliminating the need for high-temperature conditions that cause bubble formation and mechanical property degradation
Solution Approach 2:
The patent replaces the mechanical/thermal approach (high temperature heating) with a chemical catalytic approach using phosphorous compounds. This substitution enables reaction acceleration without relying on thermal energy, thus avoiding the harmful effects of high-temperature processing on product quality
3Productivity
If esterification catalysts are used to accelerate polycondensation, then reaction efficiency improves, but homogeneous catalysts remain in the product causing additional costs and processing complexity
Solution Approach 1:
The patent employs phosphorous compounds that can be easily separated from the product mixture after serving their catalytic function. These compounds act as temporary facilitators during the reaction and can be removed through standard purification techniques, avoiding the complexity of separating persistent homogeneous catalysts while maintaining high reaction efficiency
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 process produces polyester polyols with low acid numbers and APHA/HAZEN color numbers, resulting in polyurethanes with improved mechanical properties and transparency, suitable for industrial applications, including thermoplastic polyurethanes with a degree of yellowness less than 20.
Implementation Method 1
The polycondensation of multifunctional polyhydroxyl compounds and dicarboxylic acids to form polyester polyols of the AA-BB type is generally carried out on an industrial scale at high temperatures of 160 to 280 ° C
Implementation Method 2
heating the reaction mixture to a temperature of at least 210 ° C at a pressure below 1013 mbar
Implementation Method 3
In addition to the phosphorous component, which serves as a stabilizer, a catalyst for the polycondensation reaction, in particular a metal organic compound, is used
Implementation Method 4
carboxylic acids obtained from natural raw materials, which have at least two acid groups, produce light-colored polyester polyols by adding organic phosphites during the production process to polyester polyols
Implementation Method 5
heating the reaction mixture to a temperature of at least 160 ° C and separating off the water formed during the reaction
Data Source
Figure 1
AI summary
The invention relates to a method for producing a polyester polyol comprising the following method steps: (a) producing a reaction mixture comprising the following components: A: at least one carboxylic acid obtained from natural raw materials, having at least two acid groups, B: at least one multivalent alcohol, C: at least one organic phosphite compound, D: at least one Lewis acid; (b) heating the reaction mixture to a temperature of at least 160°C and separating the water that is generated during the reaction; (c) heating the reaction mixture to a temperature of at least 210°C at a pressure below 1013 mbar for a period of 0.1 to 25 hours.