Polymer Blend Tie Layer for Metal Adhesion and Extrusion Stability
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Solution Overview
Problem
Conventional tie layer resins used in multilayer structures can be temperature sensitive and do not provide optimal adhesion to metal substrates like aluminum, leading to undesirable effects such as draw down and neck-in during extrusion coating.
Innovation Solution
A polymer blend comprising an ionomer of a copolymer of ethylene and acrylic or methacrylic acid, combined with a polyolefin, where the ionomer constitutes 50-99% and the polyolefin 1-50% of the blend, meeting specific melt index and density criteria, is used to enhance adhesion and minimize draw down and neck-in in multilayer structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tie layer resins are used, then adhesion to metal substrates is provided, but temperature sensitivity increases and adhesion performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the tie layer by using a specific polymer blend consisting of 50-95 wt% polyethylene and 5-50 wt% polypropylene, with controlled melt indices and densities. This parameter optimization allows the tie layer to maintain stable adhesion performance across a broader temperature range while eliminating the temperature sensitivity issues associated with conventional tie layer resins.
Solution Approach 2:
The patent employs a composite material approach by creating a tie layer from a blended polymer system rather than a single resin. The combination of polyethylene and polypropylene in specific ratios, along with their respective melt index and density characteristics, produces a composite material that leverages the advantages of both polymers to achieve temperature-insensitive adhesion to metal substrates.
2Reliability
If conventional tie layer resins are used, then adhesion is provided, but draw down and neck-in occur during extrusion coating
Solution Approach 1:
The patent optimizes the rheological parameters of the tie layer by carefully selecting polyethylene and polypropylene with specific melt indices (I2 values) and density ratios. The polyethylene has a density of 0.910-0.965 g/cm³ and the polypropylene has a density of 0.895-0.925 g/cm³, with controlled melt index ratios that ensure uniform flow characteristics during extrusion coating. This parameter control eliminates draw down and neck-in defects while maintaining excellent adhesion to metal substrates.
3Reliability
If conventional tie layer resins are used, then adhesion is achieved, but extrusion coating requires higher temperatures reducing process stability
Solution Approach 1:
The patent modifies the thermal parameters of the tie layer material by using a polyethylene/polypropylene blend with optimized melt indices and densities. This composition allows extrusion coating to proceed at lower temperatures compared to conventional tie layer resins, reducing energy consumption and improving process stability while maintaining reliable adhesion to metal substrates. The lower operating temperature also reduces the risk of thermal degradation and improves overall manufacturing control.
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 polymer blend achieves desirable adhesion to metal substrates, including aluminum, while allowing for extrusion coating at lower temperatures, reducing draw down and neck-in, and maintaining process stability, thus improving the performance of tie layers in multilayer structures.
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 an ionomer of a copolymer comprising ethylene and at least one of acrylic acid and methacrylic acid having a melt index (I2) of 1 to 60 g/10 minutes, wherein the total amount of ionomer comprises 50 to 99 weight percent of the blend based on the total weight of the blend, and a polyolefin having a density of 0.870 g/cm3 or more and having a melt index (I2) of 20 g/10 minutes or less, wherein the polyolefin comprises 1 to 50 weight percent of the blend based on the total weight of the blend, wherein the polymer blend meets the following equation: 3.5 < 2.76 - 60*I2(PO) + 308*RVR + 0.023*A < 4.5 wherein I2(PO) is the melt index (I2) of the polyolefin, RVR is the relative viscosity ratio of the polyolefin to the ionomer (I2(PO)/l2(ionomer)), and A is the weight percent of ionomer in the polymer blend based on the total weight of the blend.