Modified EVOH Coating Agent for Low-Temperature Storage Stability

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Solution Overview

Problem

Existing ethylene-vinyl alcohol copolymer (EVOH) solutions suffer from poor storage stability, particularly at low temperatures, leading to gel formation and thickness unevenness in coating films, which compromises gas barrier properties and recyclability, and laminates with ethylene-modified polyvinyl alcohol resin may crack under bending, affecting package storability.

Innovation Solution

A coating agent comprising a modified ethylene-vinyl alcohol copolymer with specific structural units and saponification degrees, combined with inorganic microparticles and a solvent, provides enhanced storage stability and maintains gas barrier properties even after bending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional EVOH solutions are stored at low temperature, then storage cost is reduced, but the solution gels and loses stability

Engineering Contradiction:

Improvestorage temperatureVSAvoidsolution stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent introduces a novel EVOH copolymer with specific compositional parameters (vinyl alcohol content: 70-80 mol%, vinyl acetate content: 5-15 mol%, ethylene content: 10-30 mol%) and controlled molecular weight distribution (Mw/Mn: 1.5-3.0) to change the fundamental properties of the polymer, enabling stable storage at low temperatures without gelation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating system by combining the novel EVOH copolymer with specific additives including antioxidants (0.1-5.0 wt%), UV absorbers (0.1-5.0 wt%), and processing aids (0.1-5.0 wt%), forming a stable composite material that maintains reliability across varying storage conditions

Inventive Principle:

Principle #40Composite materials

2Reliability

If EVOH layer thickness is increased to ensure gas barrier properties, then gas barrier performance is improved, but material usage increases and recyclability is compromised

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidEVOH content

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent optimizes the vinyl alcohol content to 70-80 mol% (higher than conventional EVOH) to enhance gas barrier properties at molecular level, allowing thinner layers to achieve the same barrier performance, thereby reducing overall EVOH quantity needed while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies surface treatment or coating optimization to concentrate gas barrier functionality at the critical interface regions, achieving high barrier performance with minimal EVOH material through localized enhancement rather than uniform thickness increase

Inventive Principle:

Principle #3Local quality

3Shape

If EVOH solution is coated and dried under strict conditions to prevent whitening, then coating appearance is improved, but process complexity increases

Engineering Contradiction:

Improvecoating film appearanceVSAvoiddrying condition control

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

The patent incorporates antioxidants and stabilizers that provide temporary protection during storage and processing, allowing broader drying condition windows without whitening, thereby reducing the need for complex condition control systems

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent modifies the polymer's chemical composition and adds stabilizing agents to change the coating system's resistance to oxidation and whitening, enabling simplified drying processes while maintaining good appearance

Inventive Principle:

Principle #35Parameter changes

4Reliability

If ethylene-modified polyvinyl alcohol resin is used in laminates, then gas barrier properties are improved, but the laminate cracks under bending

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidflexural strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent develops a multilayer composite structure where the novel EVOH copolymer layer is combined with flexible polyolefin layers (PE, PP, or their copolymers) in specific thickness ratios, creating a composite that achieves high gas barrier properties while maintaining flexural strength and crack resistance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent positions the high-barrier EVOH copolymer layer strategically within the laminate structure (e.g., as an intermediate barrier layer between flexible outer layers) to provide gas barrier functionality where needed while allowing outer layers to provide mechanical flexibility and crack resistance

Inventive Principle:

Principle #3Local quality

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 modified ethylene-vinyl alcohol copolymer coating agent ensures stable film formation with good appearance and gas barrier properties, maintaining performance even after bending and under varying storage conditions.

Implementation Method 1

a water-containing alcohol solution of an EVOH modified with vinylpyrrolidone is excellent in storage stability

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

the modified ethylene-vinyl alcohol copolymer (A) contains structural units (Ia), (Ib), and (Ic)

Methodology Applied

Scientific EffectHydrogen bonding:

Data Source

PatentUS20250326946A1Coating agent and multilayer structure using same

Publication Date: 2025.10.23 KURARAY CO LTD

AI summary

The present disclosure provides a coating agent containing a modified ethylene-vinyl alcohol copolymer.