Multi-Layer Polyester-Polyamide Food Casing for High-Temperature Strength
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Solution Overview
Problem
Existing food casings lack sufficient mechanical strength and barrier properties, particularly at higher temperatures, leading to deformation and leakage during cooking, and there is a need for cost-effective materials that maintain strength with reduced wall thickness while ensuring oxygen and water vapor barrier functionality.
Innovation Solution
A biaxially stretch-oriented, at least 5-layer tubular food casing with a polyester-based layer containing 15-49% partially aromatic polyamide, combined with aliphatic polyamide and polyolefin layers, achieved through coextrusion and subsequent biaxial stretching, which enhances mechanical strength and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the wall thickness of the casing is reduced to lower material costs, then material cost decreases, but mechanical strength becomes insufficient leading to deformation and leakage
Solution Approach 1:
The patent applies composite materials by creating a multi-layer casing structure where a polyester layer is combined with a polyamide layer. The polyester layer provides cost-effectiveness and good barrier properties, while the polyamide layer contributes high mechanical strength and temperature resistance. This composite structure allows the overall wall thickness to be reduced while maintaining sufficient mechanical strength, as each layer compensates for the limitations of the other.
Solution Approach 2:
The casing is segmented into multiple functional layers with distinct roles. The polyester layer handles cost reduction and barrier functionality, while the polyamide layer specifically addresses mechanical strength requirements. This segmentation allows optimization of each layer for its specific function, enabling thin-wall design without sacrificing overall performance.
2Loss of substance
If the wall thickness is reduced, then material cost decreases, but barrier properties against oxygen and water vapor deteriorate
Solution Approach 1:
The composite structure combines polyester and polyamide layers, each contributing different barrier properties. The polyester layer provides effective barrier properties against oxygen and water vapor, while the polyamide layer adds complementary barrier functionality. This synergistic combination maintains superior barrier performance even at reduced wall thickness, as the multi-layer structure creates multiple diffusion paths that hinder gas and vapor penetration.
Solution Approach 2:
The barrier function is enhanced by adding a dimensional aspect through multiple layers. Instead of relying on a single thick layer, the patent uses multiple thinner layers stacked together, creating a multi-dimensional barrier structure. This increases the tortuosity of diffusion paths for oxygen and water vapor, improving barrier properties while keeping the overall thickness reduced.
3Strength
If aliphatic polyamide is used to achieve sufficient strength, then mechanical strength improves, but material cost increases
Solution Approach 1:
The patent creates a cost-effective composite by combining expensive polyamide with more economical polyester. The polyamide layer is applied only where maximum strength is critical, while the polyester layer covers areas where cost reduction is prioritized. This composite approach achieves the required mechanical strength without using 100% polyamide, thereby reducing overall material cost.
Solution Approach 2:
The casing structure applies local quality by concentrating the expensive polyamide material only in specific layers or regions where maximum mechanical strength is most needed, while using the more cost-effective polyester in other areas. This localized application of high-performance material optimizes the strength-to-cost ratio.
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 solution provides a food casing with improved specific strength, retained at high temperatures, and maintains effective oxygen and water vapor barrier properties, preventing deformation and leakage, even with thinner walls, while being cost-effective.
Implementation Method 1
the required strength is achieved by layer structures which consist predominantly (i.e. more than 50% by weight) of mechanically relatively strong and well temperature-resistant aliphatic polyamides or in which the sum of the layers consists of predominantly aliphatic polyamide 50% of the total film thickness. In addition, the polyamide-containing casings are usually biaxially stretch-oriented during production. The stretching of polyamide leads to a significantly increased specific tear strength and also improves the dimensional stability (resilient elasticity) of the casing under the weight of the filling material.
Implementation Method 2
The sausages formed are cooked or sterilized by heating to a core temperature of at least 76°C, sometimes up to 130°C
Implementation Method 3
even bursting during the thermal expansion of the filling material during heating
Data Source
AI summary
The invention relates to an at least five-layered, biaxially extended, tubular-shaped food casing comprising at least one layer which is based on thermoplastic polyester and partially aromatic (co-)polyamide. The invention further relates to the use thereof as an artificial sausage casing and to a method for the production thereof.