Aliphatic-Aromatic Polyester Composition for Low Yellowness
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Solution Overview
Problem
Existing biodegradable polyesters face challenges in simultaneously achieving a low yellowness index and better hydrolysis resistance, particularly when using adipic acid and titanium compounds as catalysts, leading to color issues and decreased hydrolytic stability.
Innovation Solution
An aliphatic-aromatic polyester composition is developed with specific molar percentages of aromatic and aliphatic dicarboxylic acids, aliphatic dihydroxy compounds, and controlled titanium content, along with a preparation method that includes esterification, transesterification, and polycondensation reactions, followed by a chain extension and tetrahydrofuran treatment to achieve low yellowness and improved hydrolysis resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a titanium compound is used as catalyst during synthesis of aliphatic-aromatic polyester from adipic acid, then the polyester has good biodegradability and less toxic residue, but the polyester shows yellow to red coloration which fails to meet color requirements
Solution Approach 1:
The patent changes the chemical parameters of the system by introducing a phosphorus compound as a passivator that modifies the catalytic activity and coloration characteristics of the titanium compound. This parameter change allows maintaining biodegradability while suppressing unwanted coloration.
Solution Approach 2:
The phosphorus compound acts as an intermediary substance that mediates between the titanium catalyst and the polyester formation process. It passivates the titanium catalyst to reduce toxic residue and control coloration while preserving the biodegradability function.
2Object-affected harmful factors
If a phosphorus compound is added as passivator to improve color, then the yellowness index increases, but the acid number increases leading to decreased hydrolysis resistance
Solution Approach 1:
The patent optimizes the concentration parameter of the phosphorus compound passivator to achieve the desired balance. By controlling the amount of phosphorus compound added, the system achieves low yellowness index while limiting the increase in acid number to maintain hydrolysis resistance.
3Strength
If traditional chemical fiber materials are used, then the materials have good mechanical properties and durability, but the materials are difficult to degrade in nature causing white pollution
Solution Approach 1:
The patent creates a composite polyester material combining aliphatic and aromatic polyester components with specific dicarboxylic acids and diols. This composite structure provides both the mechanical durability needed for fiber applications and the biodegradability required to reduce pollution, replacing traditional non-biodegradable chemical fibers.
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 composition achieves a yellowness index of ≤23 and viscosity retention rate of ≥65% after boiling, demonstrating excellent hydrolysis resistance and biodegradability, suitable for polyester fibers used in masks and clothing.
Implementation Method 1
a commonly used catalyst includes a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound, or a titanium compound, most preferably the titanium compound
Implementation Method 2
The phosphorus compound, as a passivator of the titanium catalyst, weakens the activity of the titanium catalyst to a certain extent
Implementation Method 3
When the aliphatic-aromatic polyester composition is boiled in water at 60° C. for 48 h, a viscosity number retention rate n of the aliphatic-aromatic polyester composition is ≥65% after boiling in water
Data Source
AI summary
An aliphatic-aromatic polyester composition, a polyester fiber, a preparation method therefor and use thereof are provided. The aliphatic-aromatic polyester composition includes the following components: i) an aliphatic-aromatic polyester based on aliphatic and aromatic dicarboxylic acids and an aliphatic dihydroxy compound; and ii) a titanium element, wherein calculated based on a weight of the aliphatic-aromatic polyester composition, a content of the titanium element is 55-88 ppm, and an acid number of the aliphatic-aromatic polyester composition is ≤0.84 mg KOH/g according to the standard DIN EN 12634-1998.