Stretchable Multilayer Article EVOH Barrier
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Solution Overview
Problem
Existing multilayer films with EVOH barrier layers suffer from high stiffness and low stretchability, and inadequate elasticity, which limits their application in chemical-resistant clothing like suits and gloves, and there is a concern about delamination during stretching.
Innovation Solution
A multilayer article comprising a first and second thermoplastic polyurethane resin layer with a core layer of an ethylene vinyl alcohol copolymer, a hydroxyl group-containing compound with specific molecular weight and melting point, and a fatty acid metal salt, which enhances elasticity, stretchability, and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH is used as a barrier resin, then barrier properties are improved, but stretchability and elasticity deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the barrier layer by incorporating specific plasticizers (glycerol at 1-10 parts by weight and/or polyethylene glycol at 1-10 parts by weight per 100 parts by weight of EVOH) to modify the glass transition temperature and molecular mobility, thereby improving stretchability while maintaining barrier properties
Solution Approach 2:
The patent creates a composite material system by combining EVOH with plasticizers and incorporating this into a multilayer structure with TPU layers, where each layer contributes different properties (barrier, elasticity, stretchability) to achieve overall performance that neither material could provide alone
2Ease of operation
If conventional plasticizers are added to improve stretchability, then elasticity is improved, but performance deteriorates at high temperature/high humidity due to bleeding
Solution Approach 1:
The patent selects plasticizers with specific molecular weight ranges (glycerol: 92-100, polyethylene glycol: 200-1000) and controls their content (1-10 parts by weight per 100 parts by weight of EVOH) to achieve optimal balance between elasticity improvement and resistance to bleeding at high temperature/high humidity
Solution Approach 2:
The patent uses small molecular weight plasticizers that can be effectively incorporated and retained in the EVOH matrix, providing temporary plasticizing effect during service conditions without long-term migration or bleeding issues
3Reliability
If multilayer structure is used to improve barrier properties, then barrier performance is improved, but interlayer adhesion deteriorates during stretching
Solution Approach 1:
The patent designs a composite multilayer structure where TPU layers are bonded to EVOH barrier layers, with each layer optimized for its specific function while ensuring compatible interfacial properties to prevent delamination during stretching
Solution Approach 2:
The patent applies different material properties to different layers: the TPU layers provide elasticity and adhesion, while the EVOH layers provide barrier properties, with each layer's thickness and composition optimized for its local function in the overall structure
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 solution provides a multilayer article with improved elasticity, stretchability, and barrier properties, preventing delamination and maintaining performance under abusive conditions, suitable for chemical-resistant clothing.
Implementation Method 1
In order to improve stretchability of EVOH at room temperature, it has been proposed to add a plasticizer. Conventionally, plasticizers used for EVOH resin are propanediol, butanediol, pentanediol, propanetriol, glycerol and the like
Implementation Method 2
there is a concern about delamination between a barrier layer and other layers due to stress during stretching; therefore, in addition to the stretchability of the barrier layer, good interlayer adhesion strength is also expected for such a multilayer article
Data Source
AI summary
A multilayer article comprising at least a first layer of a thermoplastic polyurethane (TPU) resin composition, a second layer of a TPU resin composition and a core layer between the first layer and the second layer, the core layer comprising a barrier resin composition, wherein the barrier resin composition comprises an ethylene vinyl alcohol copolymer (EVOH) (A), a hydroxyl group containing compound (B) having a molecular weight of 200 or less, a ratio of a number of hydroxyl groups in one molecule relative to the molecular weight within a range of form 0.02 to 0.03, and a melting point of from about 23° C. to about 200° C., and a fatty acid metal salt (C), the multilayer article having good elasticity, stretchability and barrier properties suitable for use in chemical suits and gloves.