EVOH Multilayer Structure for Hydrolysis-Resistant Interlayer Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multilayer structures with EVOH layers experience interfacial peeling due to decreased interlayer adhesive force when exposed to harsh environments such as hot water, high temperature, acid, or alkali over time, leading to deterioration of barrier properties.
Innovation Solution
A multilayer structure comprising layers of ethylene-vinyl alcohol copolymer (EVOH) with a carboxy group and lactone ring, and modified polyolefin with a basic nitrogen-containing group, where the EVOH has a total amount of carboxy group and lactone ring between 0.08 mol % and 0.4 mol % of the ethylene, vinyl alcohol, and vinyl ester units, forming a strong chemical bond that resists hydrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional multilayer structure with EVOH layer and polyolefin layer is used, then the structure provides barrier properties, but interfacial peeling occurs due to decreased interlayer adhesive force in harsh environments
Solution Approach 1:
The invention changes the chemical parameters of the adhesive layer by introducing basic nitrogen-containing groups (such as amino or imino groups) into the polyolefin layer. This chemical modification enables strong chemical bonding with the carboxy groups and lactone rings in the EVOH layer, transforming the adhesive mechanism from physical adhesion to chemical bonding, thereby maintaining stable interlayer adhesion in harsh environments
Solution Approach 2:
The invention creates a composite adhesive layer system combining modified polyolefin with basic nitrogen-containing groups and EVOH with carboxy groups and lactone rings. This composite structure leverages the complementary chemical properties of both materials to form a stable chemical bond interface that resists degradation in harsh environments while maintaining barrier properties
2Duration of action of stationary object
If the multilayer structure is exposed to hot water, acid, or alkali for a long period, then the structure provides durability, but interlayer adhesive force decreases causing peeling
Solution Approach 1:
The invention applies preliminary anti-action by pre-introducing basic nitrogen-containing groups into the polyolefin layer before exposure to harsh environments. These groups proactively form chemical bonds with the EVOH layer's carboxy groups and lactone rings, creating a pre-established chemical bond network that actively resists the degrading effects of hot water, acid, and alkali exposure, preventing interfacial peeling throughout the service life
3Ease of manufacture
If carboxylic acid-modified polyolefin is used as adhesive layer, then lamination between EVOH and polyolefin is achieved, but interlayer adhesive force decreases in harsh environments
Solution Approach 1:
The invention changes the chemical parameters of the adhesive layer by replacing carboxylic acid modification with basic nitrogen-containing group introduction in the polyolefin. This parameter change transforms the bonding mechanism from simple acid-base interaction to stronger chemical bonding, while maintaining lamination capability during manufacturing. The basic nitrogen-containing groups provide both ease of lamination during production and sustained adhesive force in harsh service environments
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 multilayer structure maintains a strong initial interlayer adhesive force and prevents decrease even in harsh environments, reducing the likelihood of interlayer peeling and enhancing durability and barrier properties.
Implementation Method 1
the ethylene-vinyl alcohol copolymer (a) has at least one of a carboxy group and a lactone ring... a multilayer structure including: one or a plurality of layer (A) constituted from a resin composition (A) containing an ethylene-vinyl alcohol copolymer (a)... and one or a plurality of layer (B) constituted from a resin composition (B) containing a modified polyolefin (b) which has a basic nitrogen-containing group... at least one of the layer (A) and at least one of the layer (B) are directly laminated
Data Source
AI summary
Provided are: a multilayer structure having a strong initial interlayer adhesive force, with a decrease of the interlayer adhesive force being prevented even in a case of use in a harsh environment such as exposure to hot water, an acid, or an alkali for a long period of time; a method for producing such a multilayer structure; and a sheet for preventing diffusion of hazardous substances, a landfill geomembrane, and a multilayer pipe, each including such a multilayer structure.