Polyester Laminates with Cyclic Acetal Diol Units for Food Packaging
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Solution Overview
Problem
Conventional polyethylene laminates are inadequate for food packaging due to poor gas barrier properties, fragrance preservation, and adsorptivity of nutritive components, while poly(ethylene terephthalate) offers better gas barrier and fragrance preservation but lacks heat sealability and suitable melt strength for extrusion lamination.
Innovation Solution
Polyester laminates with a surface layer containing a polyester resin composed of diol units with a cyclic acetal structure, combined with other resin or paper layers, enhancing heat sealability and fragrance preservation while maintaining stable production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polyethylene is used for laminates, then heat sealability is good, but gas barrier properties and fragrance preservation are poor
Solution Approach 1:
The patent uses a composite laminate structure with multiple layers: a polyethylene heat-sealable layer combined with a polyester layer containing cyclic acetal diol units. This composite structure allows the polyethylene layer to provide heat sealability while the polyester layer provides gas barrier properties and fragrance preservation, thus resolving the contradiction between heat sealability and gas barrier performance.
2Object-affected harmful factors
If poly(ethylene terephthalate) is used, then gas barrier properties and fragrance preservation are improved, but heat sealability and melt strength are poor
Solution Approach 1:
The patent creates a composite laminate where poly(ethylene terephthalate) or similar polyester provides gas barrier and fragrance preservation properties, while a separate polyethylene layer provides heat sealability. The cyclic acetal diol units in the polyester component enhance melt strength without compromising the other properties, thus resolving the contradiction between gas barrier performance and heat sealability.
Solution Approach 2:
The patent modifies the polyester composition by incorporating cyclic acetal diol units (5-50 mol%) into the polyester structure. This compositional parameter change enhances the melt strength and heat sealability of the polyester component while maintaining its gas barrier properties, allowing the polyester to contribute more effectively to heat sealability in the composite laminate.
3Ease of operation
If copolymerized poly(ethylene terephthalate) is used to improve heat sealability, then heat sealability is good, but melt strength becomes insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the polyester by incorporating cyclic acetal diol units (5-50 mol%) into the polyester structure. This compositional modification enhances the melt strength of the polyester component while maintaining or improving heat sealability, thus resolving the contradiction between heat sealability and melt strength that plagues conventional copolyester approaches.
Data Source
AI summary
A polyester laminate including at least one polyester layer C and at least one layer selected from the group consisting of a resin layer D and a paper layer E. The polyester layer C is made of a polyester resin A in which from 5 to 80 mol % of the total diol units is a diol unit having a cyclic acetal structure. The resin layer D is made of a resin other than the polyester resin A. At least one surface layer of the polyester laminate is the resin layer C. The polyester laminate is particularly suited as a container for preserving food because of its excellent heat sealability and high fragrance preservation.