Copolymerized Polyester Resin Composition to Reduce Die Staining
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Solution Overview
Problem
The continuous production of film, molded products, or fibers using copolymerized polyester resins faces issues such as die staining, foreign matter adhesion, recycling stability, coloration, and molecular weight decrease due to heat and thermal oxidation.
Innovation Solution
A copolymerized polyester resin with specific compositions and processing conditions is developed, including a content of cyclic dimers within certain limits, the use of ethylene glycol, diethylene glycol, and triethylene glycol, and a carboxyl end group concentration range of 8 to 25 eq/t, along with a catalyst combination of aluminum and phosphorus compounds instead of traditional antimony compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If copolymerized polyester resin is used for continuous production of film and molded products, then transparency and moldability are improved, but die staining and foreign matter adhesion occur
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carboxyl end group concentration (AV value) within 8-25 eq/t and limiting cyclic dimer content to 7000 ppm or less. These parameter optimizations modify the resin's chemical composition to reduce die staining and foreign matter adhesion while maintaining transparency and moldability.
2Productivity
If copolymerized polyester resin is recycled, then productivity is improved, but coloration and molecular weight decrease occur due to heat and thermal oxidation
Solution Approach 1:
The patent applies preliminary action by pre-stabilizing the resin composition before recycling through controlled carboxyl end group concentration (8-25 eq/t) and cyclic dimer content (≤7000 ppm). This preliminary optimization of chemical parameters enhances the resin's resistance to heat and thermal oxidation, preventing coloration and molecular weight degradation during subsequent recycling processes.
3Illumination intensity
If diethylene glycol content is increased to improve transparency and moldability, then these properties are enhanced, but stability against heat and thermal oxidation decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the diethylene glycol content within the copolymerized polyester resin and simultaneously controlling the carboxyl end group concentration (AV value) to 8-25 eq/t. This balanced parameter optimization achieves the desired transparency and moldability while compensating for the reduced heat and thermal oxidation stability through precise compositional control.
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 effectively suppresses die staining and foreign matter adhesion, enhances recycling stability and heat resistance, and maintains the transparency and commercial value of the products, while also reducing coloration and molecular weight loss upon recycling.
Implementation Method 1
polyester or, particularly, polyethylene terephthalate (PET) prepared from terephthalic acid (hereinafter, it is sometimes abbreviated as TPA) and ethylene glycol (hereinafter, it is sometimes abbreviated as EG) as starting materials
Implementation Method 2
stability of the copolymerized polyester against heat and thermal oxidation
Data Source
AI summary
The aim of the present invention is to provide a copolymerized polyester resin for solving the problem of die staining and foreign matter adhesion to the film etc. in the continuous production of the film etc.; and the problem of recycling property of the copolymerized polyester. This copolymerized polyester resin contains dicarboxylic acid and diol as constituting components, wherein the copolymerized polyester resin contains terephthalic acid as a main component of a dicarboxylic acid component, and contains ethylene glycol as a main component of a diol component, wherein a content of diethylene glycol is from 7 to 30% by mole and a content of triethylene glycol is from 0.05 to 2% by mole when a total amount of the whole diol component is taken as 100% by mole, wherein a content of a cyclic dimer consisting of terephthalic acid and diethylene glycol is 7000 ppm or less, and wherein a content of a cyclic dimer consisting of terephthalic acid, diethylene glycol and triethylene glycol is 200 ppm or less.