EVOH Composite Adhesion via Epoxy-Modified Bonding Agent
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Solution Overview
Problem
Multilayer composite pipes used in motor vehicles face inadequate barrier action against alcohols and water, leading to deterioration in fuel resistance and mechanical performance over time, due to unsatisfactory adhesion between EVOH and fluoropolymer or polyolefin layers, and existing bonding agents lack durability and fuel resistance.
Innovation Solution
A multilayer composite structure comprising an interior layer of adhesion-modified fluoropolymer or polyolefin, a bonding agent layer with a graft copolymer containing polyamine and polyamide, and an EVOH layer, where the bonding agent includes specific monomers and additives to enhance adhesion and resistance to fuels and heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluoropolymer layer and EVOH layer are joined by bonding agents to achieve adhesion, then adhesion between layers is improved, but fuel resistance and heat distortion resistance deteriorate due to soluble constituents
Solution Approach 1:
A polyolefin bonding agent layer serves as an intermediary between the fluoropolymer and EVOH layers. This bonding agent contains epoxy groups that chemically react with both surfaces, creating strong covalent bonds while the polyolefin base provides fuel and heat resistance, eliminating the need for soluble coupling agents.
Solution Approach 2:
The bonding agent modifies the chemical parameters of the interface by introducing epoxy functional groups that react with surface hydroxyl groups on both fluoropolymer and EVOH. This chemical modification creates permanent crosslinked bonds that maintain adhesion under fuel and heat exposure.
2Reliability
If polyolefinic interior layer is used to improve barrier action against alcohols and protect EVOH from water, then barrier action against alcohols is improved, but satisfactory adhesion is difficult to achieve
Solution Approach 1:
The bonding agent exhibits different properties at different locations: it has polyolefin characteristics for fuel resistance in the bulk, but epoxy functional groups at the interfaces for chemical bonding. This local differentiation of properties enables both adhesion and chemical resistance.
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 achieves strong and durable adhesion between layers, maintaining barrier action and mechanical integrity even after long-term exposure to fuels and heat, reducing hydrocarbon emissions and improving chemical resistance.
Implementation Method 1
a bonding agent layer II which has the following composition: a) from 0 to 80 parts by weight of a graft copolymer prepared using the following monomers: from 0.5 to 25% by weight of a polyamine having at least 4 nitrogen atoms
Implementation Method 2
These objects are achieved by a multilayer composite which comprises the following layers: I. an interior layer I selected from among an adhesion-modified or unmodified fluoropolymer molding composition and an adhesion-modified or unmodified polyolefin molding composition; II. a bonding agent layer II
Implementation Method 3
a multilayer composite which has a barrier layer comprising an ethylene-vinyl alcohol copolymer (EVOH) and a protective layer comprising a material which forms a barrier against alcohols
Data Source
AI summary
A multilayer composite which comprises the following layers: I. an interior layer I selected from among a fluoropolymer molding composition and a polyolefin molding composition; II. a bonding agent layer II which has the following composition: a) from 0 to 80 parts by weight of a polyamine-polyamide graft copolymer, b) from 0 to 85 parts by weight of polyamide, c) from 0 to 85 parts by weight of a polymer selected from among fluoropolymers and polyolefins; with the sum of the parts by weight of a), b) and c) being 100; and, in addition, the sum of the components a) and b) comprising at least 20 parts by weight of monomer units derived from caprolactam and/or the combination hexamethylenediamine/adipic acid, hexamethylenediamine/suberic acid, hexamethylenediamine/sebacic acid, hexamethylenediamine/dodecanedioic acid, hexamethylenediamine/isophthalic acid or hexamethylenediamine/terephthalic acid and d) not more than 50 parts by weight of additives selected from among impact-modifying rubber and customary auxiliaries and additives; III. a layer III comprising an EVOH molding composition, has improved adhesion of the layers.