Coextrusion Binder Composition for EVOH PS PET Adhesion
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Solution Overview
Problem
Current coextrusion binder formulations fail to provide effective adhesion between ethylene vinyl alcohol (EVOH), polystyrene (PS), and polyethylene terephthalate (PET) while maintaining transparency, as existing solutions either lack sufficient adhesion or result in undesirable coloring.
Innovation Solution
A thermoplastic coextrusion binder composition comprising 70-90% ethylene-vinyl acetate copolymer and 10-30% ethylene-ethyl acrylate/methyl acrylate-vinyl acetate-maleic anhydride terpolymer, which ensures good adhesion and transparency when used in multilayer structures with EVOH, PS, and PET.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ethylene/vinyl acetate grafted maleic anhydride copolymer is used as coextrusion binder, then adhesion with EVOH, PS and PET is achieved, but pink coloring of the packaging occurs which is not acceptable
Solution Approach 1:
The patent uses a composite binder formulation combining ethylene-vinyl acetate copolymer (70-90%) with maleic anhydride-grafted polyolefin (10-30%). This composite approach allows the EVA component to provide transparency and prevent pink coloring, while the maleic anhydride-grafted polyolefin component provides the necessary adhesion to EVOH, PS, and PET layers, thus resolving the contradiction between adhesion strength and color stability.
2Strength
If maleic anhydride grafted polyolefins are used, then adhesion between polyolefins and polar barrier materials is obtained, but other materials such as polystyrene or PET cannot be combined
Solution Approach 1:
The patent creates a universal binder composition that can adhere to multiple different materials (EVOH, PS, PET, and polyolefins) through the synergistic combination of two binder components. The ethylene-vinyl acetate copolymer provides compatibility with polar materials like EVOH, while the maleic anhydride-grafted polyolefin provides compatibility with non-polar materials like PS and PET, achieving multi-functionality and broad material compatibility in a single binder system.
3Strength
If formulations containing maleic anhydride-grafted polyolefins and styrenic polymers are used, then cohesion between polyolefins, EVOH and PS is obtained, but PET cannot be combined with EVOH or PS
Solution Approach 1:
The patent merges two previously separate binder systems into a single composite formulation. The ethylene-vinyl acetate copolymer component addresses the compatibility issue with PET, while the maleic anhydride-grafted polyolefin component maintains the cohesion between polyolefins, EVOH, and PS. By combining these two components in specific proportions (70-90% EVA and 10-30% grafted polyolefin), the patent achieves universal compatibility across all material types including PET.
4Ease of manufacture
If a single material is used for packaging, then manufacturing is simple, but performance requirements cannot be met
Solution Approach 1:
The patent employs composite materials at the binder formulation level, combining ethylene-vinyl acetate copolymer and maleic anhydride-grafted polyolefin in determined proportions. This composite binder enables the coextrusion of multiple performance layers (barrier, mechanical, adhesive) in a single integrated packaging structure, meeting diverse performance requirements while maintaining manufacturing efficiency through a unified binder system.
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 composition achieves satisfactory adhesion and transparency, facilitating easy processability and preventing delamination in multilayer packaging, with adhesion measurements exceeding 2N/15mm in peel tests and maintaining transparency without coloring issues.
Implementation Method 1
a combination of two polyolefins, in well-determined proportions, of a very particular type of EVA and of a specific class of terpolymer makes it possible to obtain a transparent mixture having very satisfactory properties in coextrusion with EVOH, PS and/or PET
Data Source
AI summary
The invention relates to a composition comprising: between 70 and 90 wt. % of copolymers of ethylene and vinyl acetate, in relation to the weight of said composition, the vinyl acetate representing between 5 and 40 wt. % of said copolymer; and between 10 and 30 wt. %, in relation to the weight of said composition, of terpolymer of ethylene - ethyl/methyl acrylate or vinyl acetate - maleic anhydride. The invention also relates to a multilayer structure comprising said composition, to the use of said composition for producing a multilayer structure, and to a method for producing said composition.