EVOH Thermoformed Container Carbonyl Additive Defect Inhibition

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Solution Overview

Problem

Ethylene-vinyl alcohol copolymer (EVOH) layers in thermoformed containers are inferior in thermoformability, leading to defects like pinholes and cracks, and impair gas barrier and mechanical strength, while existing solutions like adding plasticizers or polyamides compromise gas barrier properties.

Innovation Solution

Incorporating a carbonyl compound, such as unsaturated aldehydes, saturated aldehydes, or saturated ketones, within a specified range (0.01 ppm to 100 ppm) into the EVOH layer to inhibit defects and improve thermoformability, and optionally using a conjugated polyene compound to further enhance oxidative stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If EVOH layer is used to achieve superior oxygen barrier properties, then gas barrier properties are improved, but thermoformability deteriorates leading to pinholes and cracks

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidthermoformability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameters of the EVOH layer by incorporating specific amounts of unsaturated aldehyde (0.01-5 ppm) and saturated aldehyde or saturated ketone (1-100 ppm). This compositional modification allows the material to maintain its gas barrier properties while improving thermoformability, enabling successful thermoforming without pinholes or cracks.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite EVOH material by combining EVOH with specific carbonyl compounds (unsaturated aldehyde, saturated aldehyde, or saturated ketone). This composite approach allows the material to exhibit both the gas barrier properties of EVOH and the improved thermoformability provided by the carbonyl compound additives.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If plasticizer is added to improve thermoformability, then ease of manufacture is improved, but gas barrier properties deteriorate

Engineering Contradiction:

ImprovethermoformabilityVSAvoidgas barrier properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Instead of using conventional plasticizers that compromise gas barrier properties, the patent changes the chemical composition by incorporating specific carbonyl compounds (unsaturated aldehyde, saturated aldehyde, or saturated ketone) in controlled amounts. This compositional change improves thermoformability while preserving the gas barrier properties of EVOH.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If polyamide is blended to improve thermoformability, then ease of manufacture is improved, but gas barrier properties deteriorate

Engineering Contradiction:

ImprovethermoformabilityVSAvoidgas barrier properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces polyamide blending with a different compositional approach: incorporating specific carbonyl compounds (unsaturated aldehyde at 0.01-5 ppm, and saturated aldehyde or saturated ketone at 1-100 ppm). This parameter change achieves improved thermoformability without the gas barrier property deterioration associated with polyamide blending.

Inventive Principle:

Principle #35Parameter changes

4Manufacturing precision

If crotonaldehyde is added during polymerization to inhibit scale adhesion, then manufacturing precision is improved, but long-run workability deteriorates due to complete elimination in washing step

Engineering Contradiction:

Improveadhesion inhibitionVSAvoidlong-run workability

Core Design Contradiction:

Manufacturing precisionVSDuration of action of stationary object

Solution Approach 1:

The patent uses unsaturated aldehyde as an intermediary substance that performs the scale adhesion inhibition function during polymerization (similar to crotonaldehyde) but has the advantage of remaining in the final product. The unsaturated aldehyde serves as a mediator that provides both the adhesion inhibition benefit and the long-run workability improvement by persisting through the washing step.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3048058B1Thermoformed container and production method thereof

Publication Date: 2022.04.27 KURARAY CO LTD

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AI summary

Provided is a thermoformed container having a superior appearance as a result of inhibition of coloring and generation of defects during the melt molding, having sufficient strength, and further having a self-purge feature in a production process. The thermoformed container includes an EVOH layer (A) containing an ethylene-vinyl alcohol copolymer (I) as a principal component, wherein the EVOH layer (A) contains a carbonyl compound (II), the carbonyl compound (II) is an unsaturated aldehyde (II-1), a saturated aldehyde (II-2), a saturated ketone (II-3) or a combination thereof, and the content of the carbonyl compound (II) in the EVOH layer (A) is 0.01 ppm or greater and 100 ppm or less. The carbonyl compound (II) is preferably an unsaturated aldehyde (II-1), and the unsaturated aldehyde (II-1) is preferably an unsaturated aliphatic aldehyde.