Polyester Blow-Molded Article Mold Staining Prevention
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Solution Overview
Problem
Conventional polyester blow-molded articles face issues with long-term transparency and heat-resistant dimensional stability due to mold staining and degradation, leading to reduced productivity and commercial value, especially during high-speed continuous molding.
Innovation Solution
A polyester resin composition containing 0.035 to 1.75 equivalent/ton of hindered phenol structural units and antimony compounds as a polymerization catalyst, with cyclic trimer content less than 0.5% by mass and acetaldehyde content less than 50 ppm, is used to create a heat-resistant blow-molded article that maintains transparency and stability during extended molding without mold cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed continuous molding is performed to increase productivity, then production efficiency is improved, but mold staining occurs and transparency deteriorates over time
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester resin by incorporating specific antioxidants (0.035 to 1.75 equivalent/ton of hindered phenol structural units) and controlling cyclic trimer content (less than 0.5% by mass) and acetaldehyde content (less than 50 ppm). These parameter changes in the resin composition prevent degradation during high-speed continuous molding, allowing sustained transparency and eliminating mold staining even after 10,000+ molding cycles.
2Stability of the object's composition
If heat treatment is applied to enhance heat resistance of the cap part, then heat-resistant dimensional stability is improved, but crystallization time increases and productivity decreases
Solution Approach 1:
The patent modifies the resin composition parameters by adding specific antioxidants and controlling degradation products, which enables the polyester to achieve adequate crystallization faster. The improved resin stability allows the cap part to reach required crystallinity in reduced time, thus maintaining heat-resistant dimensional stability while improving productivity.
3Manufacturing precision
If mold cleaning is performed frequently to maintain transparency, then article quality is improved, but production downtime increases and productivity decreases
Solution Approach 1:
The patent applies preliminary protective action by incorporating antioxidants and controlling resin composition before molding begins. This preventive approach stops degradation and mold staining at the source, eliminating the need for frequent mold cleaning and enabling continuous molding for 10,000+ cycles without interruption.
Solution Approach 2:
The patent converts the potential harm of long-term continuous molding (which would cause degradation and staining) into a benefit by using the molding process itself to distribute the antioxidant throughout the product, while simultaneously protecting the mold surface and maintaining transparency throughout extended production.
4Manufacturing precision
If PET resin is used for blow-molded articles, then transparency and mechanical strength are achieved, but deposits form on mold surface during continuous molding
Solution Approach 1:
The patent converts the harmful degradation tendency of PET during continuous molding into a beneficial protective mechanism. By incorporating antioxidants and controlling cyclic trimer and acetaldehyde content, the resin itself becomes resistant to degradation, preventing deposit formation on the mold surface while maintaining the inherent transparency and mechanical strength of PET.
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 enables efficient production of transparent, heat-resistant polyester blow-molded articles with improved dimensional stability and reduced mold staining, allowing for continuous molding over 10,000 times without mold cleaning, enhancing their suitability for food and beverage containers.
Implementation Method 1
a polyester resin composition containing 0.035 to 1.75 equivalent/ton of a hindered phenol structural unit
Implementation Method 2
containing at least one selected from the group consisting of antimony compounds as a polymerization catalyst
Implementation Method 3
the cyclic trimer content thereof being less than or equal to 0.5% by mass
Implementation Method 4
the acetaldehyde content thereof being less than or equal to 50 ppm
Data Source
AI summary
The present invention is directed to a heat-resistant polyester blow-molded article made of a polyester resin composition containing 0.035 to 1.75 equivalent/ton of a hindered phenol structural unit and containing at least one selected from the group consisting of antimony compounds as a polymerization catalyst, the cyclic trimer content thereof being less than or equal to 0.5% by mass, the acetaldehyde content thereof being less than or equal to 50 ppm and the intrinsic viscosity thereof being 0.68 to 0.90 dL/g. The present invention enables efficient production of a molded article excellent in transparency and heat-resistant dimensional stability, in particular a heat-resistant blow-molded article. Moreover, according to the present invention, there are provided a polyester resin composition which is excellent in long-term continuous moldability and hardly stains a mold and a molded article prepared therewith, and a method for molding a polyester blow-molded article using the polyester resin composition.