Use of ethylene-vinyl alcohol copolymer composition pellets, and multilayer structure

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Solution Overview

Problem

Existing multilayer packaging structures using UV absorbers in EVOH resin layers face issues with UV absorber migration and resin property deterioration due to the use of low-molecular weight compounds, necessitating high concentrations that impair resin quality.

Innovation Solution

Incorporation of an ethylene-vinyl alcohol copolymer composition with 0.01 to 100 ppm of iron compounds like ferric oxide or ferrous chloride into EVOH resin pellets, which are coextruded to form a multilayer structure, providing UV absorption without surface migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a UV absorber is included in the multilayer structure to provide UV absorbing ability, then the UV absorbing property is improved, but the UV absorber migrates to the surface through the resin, causing contact with packaged articles or making the surface sticky

Engineering Contradiction:

ImproveUV absorbing abilityVSAvoidUV absorber migration

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters by using iron compounds (0.01-100 ppm) instead of conventional organic UV absorbers. This parameter substitution eliminates migration issues while maintaining UV absorption capability, as iron compounds are inorganic and have different physical-chemical properties that prevent migration through the resin matrix.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses trace amounts of iron compounds (0.01-100 ppm) which are stable and non-migratory, replacing conventional UV absorbers that require higher concentrations and suffer from migration problems. The iron compounds serve as a long-term stable solution rather than a temporary fix.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If a large amount of UV absorber is included to impart sufficient UV absorbing ability, then the UV absorbing property is improved, but the properties of the resin are deteriorated

Engineering Contradiction:

ImproveUV absorbing abilityVSAvoidresin properties

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The invention dramatically changes the concentration parameter from high levels of organic UV absorbers (typically 0.1-5 wt%) to trace levels of iron compounds (0.01-100 ppm). This parameter change achieves sufficient UV absorption while avoiding resin property deterioration, as the iron compounds are effective at much lower concentrations and do not interfere with resin performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite system by combining EVOH resin with iron compounds. This composite approach allows the iron compounds to provide UV absorption functionality while the resin matrix maintains its structural and mechanical properties, achieving a synergistic effect where both components perform optimally.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If conventional UV absorbers are used in EVOH resin layers, then UV absorption is achieved, but the low molecular weight compounds migrate and cause surface stickiness

Engineering Contradiction:

ImproveUV absorptionVSAvoidsurface stickiness

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The invention replaces conventional organic UV absorbers with iron compounds that are stable and non-migratory. The iron compounds provide the same UV absorption function without the harmful side effect of migration and surface stickiness, effectively eliminating the problem at its source.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention turns the limitation of inorganic iron compounds (traditionally not used as UV absorbers) into an advantage. The inorganic nature of iron compounds, which would normally be considered a disadvantage for UV absorption applications, actually prevents migration and surface stickiness, converting a perceived weakness into a significant benefit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 EVOH resin composition achieves satisfactory UV absorption without resin degradation, ensuring effective protection against ultraviolet radiation for packaged items.

Implementation Method 1

an EVOH resin composition containing an iron compound in a proportion of 0.01 to 100 ppm on a metal basis based on the weight of the EVOH resin composition has a satisfactory UV absorbing ability

Methodology Applied

Scientific EffectUV absorption: Absorption (EM radiation)

Data Source

PatentEP3398990B1Use of ethylene-vinyl alcohol copolymer composition pellets, and multilayer structure

Publication Date: 2026.01.07 MITSUBISHI CHEM CORP

AI summary

An ethylene-vinyl alcohol copolymer composition is provided, which contains an ethylene-vinyl alcohol copolymer and an iron compound, wherein the ethylene-vinyl alcohol copolymer has an ethylene content of 20 to 60 mol %, wherein the iron compound is present in a proportion of 0.01 to 100 ppm on a metal basis based on the weight of the ethylene-vinyl alcohol copolymer composition. Therefore, an ethylene-vinyl alcohol copolymer composition satisfactory in UV absorbing ability can be produced by using the ethylene-vinyl alcohol copolymer composition.