Polypropylene Gas Barrier Laminate with PVA Interlayer

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Solution Overview

Problem

Current soft packaging materials, which are often multi-material composites, face challenges in recyclability due to their complex material compositions, and they require improved gas barrier properties to handle food content that undergoes heat sterilization.

Innovation Solution

A gas barrier laminate is developed, comprising a polypropylene substrate layer, a first polyvinyl alcohol resin layer with a specific mass per unit area, and a metal oxide layer, where the polyvinyl alcohol resin layers sandwich the metal oxide layer to enhance gas barrier properties and recyclability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal oxide layer is formed directly on a propylene monopolymer film surface, then gas barrier properties are improved, but the vein-like surface of the propylene monopolymer film hinders sufficient barrier properties

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidsurface smoothness

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

A polyvinyl alcohol resin layer is introduced as an intermediary between the propylene monopolymer film and the metal oxide layer. This intermediate layer fills in the vein-like surface irregularities of the propylene monopolymer film, providing a smooth substrate for metal oxide deposition and enabling sufficient gas barrier properties to be achieved.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The gas barrier structure is segmented into multiple functional layers: the propylene monopolymer film provides thermal stability, the polyvinyl alcohol resin layer provides surface smoothing and adhesion, and the metal oxide layer provides the primary gas barrier function. This segmentation allows each layer to optimize its specific function.

Inventive Principle:

Principle #1Segmentation

2Reliability

If various different materials are combined to improve packaging performance, then gas barrier properties and thermal stability are improved, but recyclability deteriorates due to multi-material composition

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidrecyclability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention applies local quality by using a polyvinyl alcohol resin layer specifically at the interface between the propylene monopolymer film and metal oxide layer, where surface smoothing and adhesion are needed, while maintaining polypropylene as the primary material for recyclability. This localized application of different materials optimizes performance only where necessary.

Inventive Principle:

Principle #3Local quality

3Reliability

If a polyvinyl alcohol resin layer is added between the propylene monopolymer film and metal oxide layer, then gas barrier properties are improved, but device complexity increases

Engineering Contradiction:

Improvegas barrier propertiesVSAvoidlaminate structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The polyvinyl alcohol resin layer is applied as a thin film coating on the propylene monopolymer film surface. This thin film approach provides the necessary surface smoothing and adhesion functions without adding significant structural complexity or thickness to the overall laminate.

Inventive Principle:

Principle #30Flexible shells and thin films

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 laminate achieves high gas barrier properties even on non-smooth polypropylene surfaces, enabling the production of mono-material packaging with high recyclability and thermal stability, suitable for food packaging that undergoes heat sterilization.

Implementation Method 1

a metal oxide layer... high gas barrier properties can be achieved

Methodology Applied

Scientific EffectPhysical barrier (metal oxide layer):

Implementation Method 2

the first polyvinyl alcohol resin layer has a mass per unit area of 0.5 to 2.5 g/m2... a surface roughness Sa of the first polyvinyl alcohol resin layer is preferably 0.2 μm or less

Methodology Applied

Scientific EffectSurface filling effect:

Data Source

PatentUS12214573B2Gas barrier laminate and packaging material using the same

Publication Date: 2025.02.04 TOPPAN INC

AI summary

A gas barrier laminate includes a polypropylene substrate layer; a first polyvinyl alcohol resin layer; and a metal oxide layer, which are laminated in this order, wherein the first polyvinyl alcohol resin layer has a mass per unit area of 0.5 to 2.5 g/m; and, a packaging material includes the above gas barrier laminate and a polypropylene sealant layer disposed on a surface of the gas barrier laminate, wherein a mass ratio of a sum of the polypropylene substrate layer and the polypropylene sealant layer to a total mass of the packaging material is 85 mass % or more.