Polyamide Film with Elastomer for Low-Temperature Flex Resistance

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Solution Overview

Problem

Polyamide films lack sufficient flex resistance in low-temperature environments and transparency, making them unsuitable for packaging materials that require both properties, especially for chilled foods and medical containers.

Innovation Solution

A polyamide film composed of a specific polyamide resin composition containing 1-10% by mass of a polyester thermoplastic elastomer, with specific elastic moduli and elastic modulus ratios, and a biaxially stretched structure, which also includes a polyvinylidene chloride resin layer for enhanced adhesion and gas barrier properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If polyamide resin film is used to ensure mechanical strength and gas barrier properties, then puncture strength and abrasion resistance are improved, but flex resistance in low-temperature environment deteriorates

Engineering Contradiction:
Improvepuncture strengthVSAvoidflex resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention uses a composite material system consisting of polyamide resin (60-90 mass%) combined with polyester thermoplastic elastomer (10-40 mass%). The polyester elastomer component provides flexibility and cold flexibility, while the polyamide provides strength and barrier properties. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both high puncture strength and excellent flex resistance at low temperatures.

Inventive Principle:
Principle #40Composite materials

2Strength

If polyamide resin film is used to ensure mechanical strength, then puncture strength is improved, but transparency deteriorates

Engineering Contradiction:
Improvepuncture strengthVSAvoidtransparency
Core Design Contradiction:
StrengthVSIllumination intensity

Solution Approach 1:

The invention controls the crystallinity and molecular structure parameters of the polyester thermoplastic elastomer to optimize transparency. By selecting specific polyester elastomers with appropriate glass transition temperatures and crystalline structures, the film achieves high transparency while maintaining the mechanical strength provided by the polyamide resin matrix. The parameter optimization of the elastomer component allows simultaneous achievement of strength and optical clarity.

Inventive Principle:
Principle #35Parameter changes

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 film exhibits improved flex resistance, reduced pinhole formation, and transparency, making it suitable for packaging materials in low-temperature environments, such as chilled foods and medical containers, while maintaining puncture strength and abrasion resistance.

Implementation Method 1

a polyamide resin composition containing 1 to 10% by mass of a polyester thermoplastic elastomer... excellent in flex resistance in a low-temperature environment

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 2

a stretched film including a polyamide resin composition... elastic moduli in MD and TD of the film are each 1.0 to 2.3 GPa; a ratio between the elastic moduli in MD and TD of the film (MD/TD) is 0.9 to 1.5

Methodology Applied
Scientific EffectMolecular orientation:

Data Source

PatentUS11326032B2Polyamide film and production method for same
Publication Date: 2022.05.10 UNITIKA LTD

AI summary

Provided is a polyamide film which is a stretched film including a polyamide resin composition containing 1 to 10% by mass of a polyester thermoplastic elastomer, wherein the polyamide film satisfies all of the following conditions (A) to (C): (A) elastic moduli in MD and TD of the film are each 1.0 to 2.3 GPa; (B) a ratio between the elastic moduli in MD and TD of the film (MD/TD) is 0.9 to 1.5; and (C) a haze of the film is 7% or less.