Polyester Resin Blend for Recycled PET Blow-Molding Processability
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Solution Overview
Problem
Existing technologies face challenges in producing high-quality plastic products from recycled polyethylene terephthalate due to foreign substances and deteriorated properties, making it difficult to achieve good processability and quality in extrusion blow molding.
Innovation Solution
A polyester resin blend is developed, comprising polyethylene terephthalate and a polyester resin with a specific structural ratio of acid and diol moieties, satisfying the equation 2≤X/(Y*Z)≤15, which enhances processability and miscibility with recycled polyethylene terephthalate, improving extrusion blow molding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If waste plastics are collected, crushed and washed, and then melt-extruded and re-pelletized to be reused, then the quantity of reusable plastic material increases, but the quality of the plastic products deteriorates due to foreign substances in the waste plastics
Solution Approach 1:
The patent introduces a specific polyester resin as an intermediary component that mediates between recycled PET and virgin PET. This resin contains reactive carboxyl groups that chemically interact with hydroxyl groups at the interfaces of recycled PET particles, acting as a bonding agent that bridges the gap between foreign substances and the matrix, thereby improving overall product quality while maintaining high recycled content
Solution Approach 2:
The patent creates a composite material system consisting of three components: recycled PET (30-70 wt%), virgin PET (5-20 wt%), and a specifically designed polyester resin (10-30 wt%). This composite approach allows each component to contribute its strengths - recycled PET provides quantity and sustainability, virgin PET provides baseline quality, and the polyester resin provides bonding and interface stabilization, achieving both high quantity and high quality simultaneously
2Productivity
If recycled polyethylene terephthalate is used in extrusion blow molding, then the productivity and reusability of plastic materials improve, but the processability and quality of molded articles deteriorate
Solution Approach 1:
The patent modifies the chemical parameters of the polyester resin by controlling the molar ratio of dicarboxylic acid to diol within 0.95-1.05 and ensuring carboxyl group content is 0.01-0.06 mmol/g. These precise parameter changes create optimal rheological and chemical properties that enable the resin to flow and bond effectively during extrusion blow molding, resolving the processability issue while maintaining high recycled content for productivity
3Quantity of substance
If foreign substances are present in waste plastics, then the quantity of recyclable material is maintained, but the miscibility and quality of the final product deteriorate
Solution Approach 1:
The polyester resin serves as a chemical intermediary that improves miscibility between foreign substances (recycled PET particles with contaminants) and the virgin PET matrix. The resin's functional groups form chemical bonds at interfaces, stabilizing the composition and creating a homogeneous structure despite the presence of diverse recycled materials
Data Source
AI summary
A polyester resin blend and a molded article formed therefrom are provided. The polyester resin blend exhibits excellent processability even if it contains recycled polyethylene terephthalate as well as virgin polyethylene terephthalate, and can provide high quality molded articles, especially by extrusion blow molding. In addition, it can be reused, and it is expected to be useful for providing continuously usable plastics that have been recently attracting attention. The polyester resin blend comprising polyethylene terephthalate; and a polyester resin having a structure in which an acid moiety derived from a dicarboxylic acid or a derivative thereof and a diol moiety derived from a diol are repeated, wherein the polyester resin comprises a residue derived from a branching agent having at least three functional groups, wherein the dicarboxylic acid or a derivative thereof comprises terephthalic acid or a derivative thereof, wherein the polyester resin comprises 5 to 19 mol % of a diol moiety derived from a comonomer other than ethylene glycol with respect to the total diol moiety, wherein the polyester resin comprises a diol moiety derived from isosorbide as the diol moiety derived from the comonomer, and the polyester resin comprises 0.1 to 15 mol % of the diol moiety derived from isosorbide with respect to the total diol moiety. The polyester resin has a processability parameter value of 2 to 15.