Multilayer Metalized CPP Film with Stiffener Core

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Solution Overview

Problem

Commercially available metallized cast polypropylene (CPP) films face issues of poor metal adhesion and bond strengths, leading to metal transfer during lamination and inadequate barrier properties, which affect the shelf life of packaged food.

Innovation Solution

A multilayer metalized cast polypropylene film comprising a metallizable skin layer with a polyolefin and antiblock, a middle core layer with homopolymer PP resin and stiffener, and a sealant layer with copolymer and antiblock, providing high metal bond strength and improved barrier properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyethylene-based metallized films are used, then metal adhesion is poor, but this leads to metal transfer during lamination and reduced barrier properties

Engineering Contradiction:

Improvemetal bond strengthVSAvoidbarrier properties

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the skin layer by using polypropylene homopolymer instead of polyethylene, and incorporates specific additives (metals, metal oxides, or metal hydroxides) at controlled concentrations (0.1-10% by weight) to enhance metal adhesion while maintaining barrier properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite skin layer combining polypropylene homopolymer with metal-containing additives (metals, metal oxides, or metal hydroxides) to achieve both strong metal adhesion and good barrier properties, overcoming the limitations of pure polyethylene-based materials

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If low molecular weight PE and LLDPE are used in the skin layer, then processing is easier, but metal adhesion deteriorates leading to poor bond strength

Engineering Contradiction:

Improveprocessing easeVSAvoidmetal bond strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the molecular weight parameter and composition of the skin layer material, specifying polypropylene homopolymer with controlled molecular weight and incorporating metal-containing additives to achieve both ease of processing and strong metal adhesion

Inventive Principle:

Principle #35Parameter changes

3Reliability

If metalized CPP films are used, then barrier properties are improved, but metal adhesion remains insufficient causing metal transfer during lamination

Engineering Contradiction:

Improvebarrier propertiesVSAvoidmetal adhesion

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent develops a composite skin layer with polypropylene homopolymer and metal-containing additives (metals, metal oxides, or metal hydroxides) that simultaneously provides good barrier properties and strong metal adhesion, preventing metal transfer during lamination

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The metal-containing additives (metals, metal oxides, or metal hydroxides) act as intermediaries between the polypropylene skin layer and the metalized layer, enhancing adhesion while maintaining the barrier properties of the film

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11964448B2Multilayer metalized cast polypropylene film (CPP)

Publication Date: 2024.04.23 COSMO FILMS LTD

AI summary

The present disclosure relates to a multilayer film comprising: a) a metallizable skin layer comprising a polyolefin and an antiblock; b) a middle core layer comprising a homopolymer PP resin and a stiffener; and c) a sealant layer comprising a copolymer and an antiblock. Said a multilayer film has high metal bond and high barrier properties and can be used in packaging of foods requiring very high metal bond and high barrier to oxygen and moisture.