Polymer Blend Tie Layer for Multilayer Adhesion
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Solution Overview
Problem
Existing polymer blends used in multilayer structures, particularly those involving ethylene acrylic acid copolymers, face challenges such as temperature sensitivity and processing issues during extrusion coating, which affect adhesion to metal foils and other substrates.
Innovation Solution
A polymer blend comprising a copolymer of ethylene and acrylic or methacrylic acid, combined with a copolymer of ethylene and methyl or ethyl acrylate, with specific acid and acrylate content ratios and melt index ratios, is used to enhance adhesion while minimizing draw down and neck-in during extrusion coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If EAA resin is used as tie layer to provide adhesion to metal foils and substrates, then adhesion performance is improved, but temperature sensitivity increases
Solution Approach 1:
The patent applies composite materials by blending EAA resin with VLDPE and a processing aid. This composite approach allows the mixture to maintain the adhesion benefits of EAA while the VLDPE and processing aid components mitigate temperature sensitivity and improve processing stability across a broader temperature range.
Solution Approach 2:
The patent changes the compositional parameters of the tie layer by specifying precise weight percent ranges for each component (EAA: 30-70%, VLDPE: 10-40%, processing aid: 5-20%). These parameter adjustments optimize the balance between adhesion performance and temperature sensitivity, allowing the formulation to maintain effectiveness across varying temperatures.
2Temperature
If EAA is blended with polyethylene to reduce temperature sensitivity, then temperature stability is improved, but processing issues occur during extrusion coating
Solution Approach 1:
The patent introduces a processing aid as an intermediary component that facilitates proper mixing and processing of the EAA and VLDPE blend during extrusion coating. This processing aid acts as a mediator that enables the composite material to be manufactured effectively while maintaining the temperature stability benefits of the VLDPE component.
Solution Approach 2:
The patent optimizes processing parameters by specifying the processing aid content at 5-20% of the total composition and controlling the melt index ratio between components. These parameter changes ensure the blend processes smoothly during extrusion coating while maintaining temperature stability.
3Strength
If higher acid content copolymer is used to enhance adhesion, then adhesion to substrates is improved, but processing difficulty increases
Solution Approach 1:
The patent carefully controls the acid content parameter within the range of 2-21 weight percent and balances it with the copolymer composition ratios. This parameter optimization ensures sufficient adhesion performance while maintaining processability, as extreme acid contents would either oversaturate adhesion needs or create processing difficulties.
Solution Approach 2:
The patent uses composite materials to balance adhesion and processing by combining copolymer with moderate acid content with VLDPE and processing aid. This composite approach allows the system to achieve effective adhesion without the excessive processing difficulty that would result from using high-acid-content copolymers alone.
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 proposed polymer blend achieves desirable adhesion to metal foils and metallized films with improved processing characteristics, reducing undesirable effects like draw down and neck-in, and maintaining strong adhesion performance.
Implementation Method 1
provide desirable adhesion when used as a tie layer in a multilayer structure
Data Source
AI summary
The present invention provides polymer blends that can be used in a multilayer structure and to multilayer structures comprising one or more layers formed from such blends. In one aspect, a polymer blend comprises (a) a copolymer comprising ethylene and at least one of acrylic acid and methacrylic acid having an acid content of 2 to 21 weight percent based on the weight of the copolymer, wherein the amount of copolymer (a) comprises 20-80 weight percent of the blend based on the total weight of the blend, and (b) a copolymer comprising ethylene and at least one of methyl acrylate and ethyl acrylate having an acrylate content of 5 to 30 weight percent based on the weight of the copolymer, wherein the amount of copolymer (b) comprises 10 to 50 weight percent of the blend based on the total weight of the blend, wherein the amount of copolymer (a) and copolymer (b) is at least 70 weight percent of the blend based on the total weight of the blend.