Thermoplastic polymer cooking article based on pet and process for making such article
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Solution Overview
Problem
Polyamide (PA) cookware yellows or stains when exposed to high temperatures, leading to hygiene concerns and limited color options, while existing PET solutions are costly due to extensive drying requirements for compounding.
Innovation Solution
A process for injection molding PET articles using non-compounded PET resin and a masterbatch containing pigments, nucleating agents, and optional additives, with PBT as a dispersant, eliminating the need for compounded PET and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyamide (PA) is used for cookware, then it can be molded by injection and has good mechanical properties, but it yellows by thermal oxidation at temperatures above 200°C and stains with lava-dishes
Solution Approach 1:
The patent changes the material parameter from polyamide to polyethylene terephthalate (PET), which has superior thermal stability and resistance to staining. PET maintains its mechanical properties at temperatures above 200°C without yellowing and does not absorb pigments from lava-dishes, thereby resolving the harmful effects while preserving injection molding capability
Solution Approach 2:
The patent uses a composite system combining PET resin with a masterbatch containing pigments and nucleating agents dispersed in polybutylene terephthalate (PBT). This composite approach allows the base PET material to provide thermal stability and stain resistance, while the PBT dispersant phase ensures uniform distribution of additives without compromising the parent material's beneficial properties
2Reliability
If polyethylene terephthalate (PET) is used as a replacement material, then it has better thermal stability and resistance to staining, but it requires extensive desiccation to reach residual water content of less than 0.02% for compounding
Solution Approach 1:
The patent performs preliminary desiccation of the PET resin before compounding, reducing the residual water content to less than 0.02%. This preliminary action prevents hydrolysis of the polymer during the compounding process, eliminating the need for extensive drying cycles during production and reducing manufacturing complexity
Solution Approach 2:
The patent extracts the water removal step from the compounding process by performing desiccation separately before compounding. This separation allows the compounding process itself to proceed without extensive drying requirements, as the water content has already been reduced to acceptable levels in the pre-treated resin
3Ease of manufacture
If compounded PET granules are used for injection molding, then the material has necessary additives for injection, but the compounding process requires extensive desiccation increasing the cost of PET compounds
Solution Approach 1:
The patent uses a masterbatch system where pigments and nucleating agents are dispersed in a PBT carrier at high concentration. This partial compounding approach allows the base PET to remain relatively simple while adding only the necessary additives in a concentrated form, reducing the overall cost compared to fully compounded PET granules
Solution Approach 2:
The patent introduces PBT as an intermediary carrier material in the masterbatch. The PBT serves as a dispersant that facilitates uniform distribution of pigments and nucleating agents, while also being compatible with PET. This intermediary approach allows efficient additive delivery without requiring expensive fully compounded PET compounds
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
Enables the production of cost-effective, thermally stable PET articles that resist yellowing and staining, allowing for the use of light colors and complex shapes without compromising mechanical properties.
Implementation Method 1
plasticizing the thermoplastic polymer composition and the masterbatch to form, in the injection cylinder, a molten plastic material
Implementation Method 2
plasticizing the thermoplastic polymer composition and the masterbatch to form, in the injection cylinder, a molten plastic material
Implementation Method 3
placing the mold at a controlled temperature to stiffen the molded article
Implementation Method 4
the presence of the nucleating agent promotes crystallization of the polymer from the polymer composition
Data Source
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Figure 3
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AI summary
The present invention relates to an injection-moulded article made up of a thermoplastic polymer material comprising a polyethylene terephthalate (PET) matrix, and at least one pigment and at least one nucleating agent dispersed in said PET matrix. According to the invention, the thermoplastic polymer material comprises no more than 5 wt% of mineral filler relative to the total weight of the article, and the article has a variable thickness ranging from 0.2 mm to 10 mm, at least two adjacent areas having a difference in thickness of at least 10%. The present invention also relates to a method for producing such an article.