Packaging sheet for elevated-temperature use

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Solution Overview

Problem

Packaging materials used at elevated temperatures often deform or lose strength, lacking transparency and thermoformability while maintaining temperature resistance.

Innovation Solution

A packaging sheet comprising a first copolyester with a glass transition temperature of 70° C. to 90° C. and a second copolyester with a glass transition temperature of 112° C. or higher, combined in specific volume ratios, providing thermal stability and clarity at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If CPET material is used for high temperature resistance, then temperature resistance is improved, but transparency deteriorates (completely opaque)

Engineering Contradiction:

Improvetemperature resistanceVSAvoidtransparency

Core Design Contradiction:

TemperatureVSIllumination intensity

Solution Approach 1:

The patent uses a composite structure with two different copolyester layers: a first copolyester layer (APET) providing transparency and ease of thermoforming, and a second copolyester layer with higher glass transition temperature providing thermal stability. This composite approach allows the packaging to achieve both transparency and high temperature resistance simultaneously, resolving the contradiction between these two properties.

Inventive Principle:

Principle #40Composite materials

2Temperature

If polypropylene material is used for high temperature resistance, then temperature resistance is improved, but ease of manufacture deteriorates (difficult to thermoform)

Engineering Contradiction:

Improvetemperature resistanceVSAvoidthermoformability

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent combines polypropylene or other high-temperature resistant materials with copolyester materials that have good thermoformability. The copolyester layer facilitates easy thermoforming during manufacturing, while the polypropylene or high glass transition temperature copolyester layer provides the necessary temperature resistance, thus resolving the contradiction between ease of manufacture and temperature resistance.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If single amorphous polyester material is used for ease of manufacture, then ease of manufacture is improved, but temperature resistance deteriorates (insufficient temperature resistance)

Engineering Contradiction:

ImprovethermoformabilityVSAvoidtemperature resistance

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent creates a multi-layer composite where the first copolyester layer provides excellent thermoformability and clarity, while the second copolyester layer with higher glass transition temperature (112°C or higher) provides enhanced temperature resistance. This composite structure allows the material to be easily thermoformed while maintaining shape stability at elevated temperatures, resolving the contradiction between ease of manufacture and temperature resistance.

Inventive Principle:

Principle #40Composite materials

4Device complexity

If single copolyester layer is used for simplicity, then device complexity is reduced, but temperature resistance deteriorates (deformation at elevated temperatures)

Engineering Contradiction:

Improvestructure complexityVSAvoidtemperature resistance

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

The patent employs a multi-layer composite structure with distinct functional layers: a first copolyester layer for transparency and thermoformability, and a second copolyester layer for thermal stability. This composite approach achieves superior temperature resistance without excessive complexity, as the layered structure is integrated into the packaging material itself rather than requiring separate components or complex assembly processes.

Inventive Principle:

Principle #40Composite materials

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 sheet maintains shape and clarity with enhanced thermoformability and stress resistance at temperatures up to 112° C., outperforming single-copolyester sheets in terms of haze and deformation resistance.

Implementation Method 1

a first layer comprising a first copolyester having a glass transition temperature of from 70° C. to 90° C.

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 2

a second layer comprising a second copolyester having a glass transition temperature of equal to or greater than 112° C.

Methodology Applied

Scientific EffectGlass transition:

Data Source

PatentUS10384854B2Packaging sheet for elevated-temperature use

Publication Date: 2019.08.20 BEMIS COMPANY INC

AI summary

A packaging sheet is described. The sheet comprises a first layer comprising a first copolyester having a glass transition temperature of from 70° C. to 90° C. and an intrinsic viscosity of from 0.70 dl/g to 0.90 dl/g. The first copolyester comprises from 50% to 85% by volume of the sheet. The sheet also comprises a second layer comprising a second copolyester having a glass transition temperature of equal to or greater than 112° C. The second copolyester comprises from 15% to 50% by volume of the sheet. The sheet is thermally stable after exposure to temperatures up to 112° C. Various embodiments of the sheet are also described.