Adhesive Resin Composition for EVOH Bonding
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Solution Overview
Problem
Current adhesives for thermoplastic resins like polyethylene and polypropylene fail to provide strong and durable bonding with ethylene/vinyl alcohol copolymers, leading to issues such as low adhesion, gel formation, and product quality degradation during processing.
Innovation Solution
A resin composition comprising a thermoplastic resin, a copolymer of ethylene and vinyl ester or acrylic acid ester with a higher vinyl ester or acrylic acid ester content, and a crosslinking agent, which is grafted and hydrolyzed to create an adhesive with improved adhesion properties, specifically designed for bonding with ethylene/vinyl alcohol copolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a graft-modified ethylenic resin composition grafted by an unsaturated carboxylic acid or its derivative is used as an adhesive for EVOH, then adhesion is excellent, but the resin in the extruder or die has increased viscosity, is colored and gelled, resulting in fish eyes and gel substances in the product
Solution Approach 1:
The patent introduces an ethylene/vinyl acetate copolymer hydrolyzate as an intermediary substance between the graft-modified ethylenic resin and EVOH. This intermediary has lower reactivity with EVOH, preventing direct harmful interactions while still enabling adhesion. The hydrolyzate acts as a buffer that reduces the aggressive chemical interaction causing gel formation and coloring, allowing the system to achieve both good adhesion and product quality.
2Stability of the object's composition
If an ethylene/vinyl acetate copolymer hydrolyzate is used as an adhesive for EVOH, then the adhesive will not be colored or gelled by repeated kneading, but adhesion to EVOH is insufficient and EVOH may be peeled when receiving impact or friction
Solution Approach 1:
The patent merges two different adhesive systems into a single composition: graft-modified ethylenic resin (which provides excellent adhesion) and ethylene/vinyl acetate copolymer hydrolyzate (which provides stability against coloring and gelling). By combining these two components, the resulting adhesive composition achieves both strong adhesion to EVOH and resistance to degradation during repeated processing, eliminating the trade-off between these two properties.
3Reliability
If EVOH is used as an interlayer in a laminate with polyolefin, then gas barrier property and aroma retention are improved, but affinity to polyolefin is very low and the two are commonly not bonded to each other
Solution Approach 1:
The patent uses the developed adhesive composition as an intermediary layer between EVOH and polyolefin. This adhesive contains components that can interact with both EVOH (through its hydrolyzed vinyl groups) and polyolefin (through its ethylenic structure), creating a bridge that enables bonding between these two incompatible materials. The intermediary adhesive transfers the bonding function, allowing the laminate to maintain both the gas barrier properties of EVOH and the structural integrity of polyolefin.
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 adhesive composition achieves excellent adhesion to both thermoplastic resins and ethylene/vinyl alcohol copolymers, preventing gel formation and maintaining product quality, even under repeated processing, while ensuring sufficient strength and durability.
Implementation Method 1
a modified product having (A) grafted by (B)
Implementation Method 2
a hydrolyzate of a resin composition containing a thermoplastic resin (A), a copolymer (B) of ethylene and a vinyl ester and/or an acrylic acid ester
Data Source
AI summary
To provide an adhesive excellent in adhesion to a thermoplastic resin and an ethylene/vinyl alcohol copolymer.An adhesive comprising a hydrolyzate of a resin composition containing a thermoplastic resin (A), a copolymer (B) of ethylene and a vinyl ester and/or an acrylic acid ester having a vinyl ester and/or acrylic acid ester content higher by at least 5 mol % than (A); and a modified product having (A) grafted by (B), and an adhesive resin composition comprising it.