Polyolefin Sausage Casing Structure for Wrinkle-Free Recyclability

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Solution Overview

Problem

Existing sausage casings with mixed polymer compositions, particularly those containing polyamide (PA), are difficult to recycle and often result in wrinkles after cooking due to insufficient stiffness and water vapor barrier, leading to non-fresh product perception.

Innovation Solution

A bi-axially oriented, multi-layered thermoplastic food casing with a high polyolefin (PO) content, featuring two identical skin layers and non-skin layers with specific density and optional porosity, ensuring recyclability and wrinkle-free sausages by maintaining stiffness and water vapor barrier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multi-layer structures with different materials (PA and PO) are used to achieve high stiffness, strength, and water vapor barrier, then the functional performance is improved, but the recyclability deteriorates due to inseparable layers

Engineering Contradiction:

Improvefunctional performance (stiffness, strength, water vapor barrier)VSAvoidrecyclability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The casing is divided into multiple layers with distinct functions: PA layers provide stiffness and strength, PO layers provide water vapor barrier, and EVOH layers provide oxygen barrier. Each layer is optimized for its specific function while maintaining overall recyclability through controlled composition

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses composite material structures combining PA, PO, and EVOH in specific configurations (e.g., PA/PO/PA, PA/EVOH/PA, or PO/PO/PO with EVOH core). These composite structures achieve the required functional performance while managing recyclability through material selection and layer arrangement

Inventive Principle:

Principle #40Composite materials

2Strength

If PA-based casings are used to achieve high stiffness and strength, then the structural integrity is improved, but the recyclability deteriorates due to mixed polymer composition

Engineering Contradiction:

Improvestiffness and strengthVSAvoidrecyclability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Different regions of the casing have different material compositions tailored to local requirements: PA layers are placed where stiffness and strength are needed (skin layers), PO layers are placed where water vapor barrier is critical (core layers), and EVOH layers are added where oxygen barrier is required. This local optimization maintains overall recyclability

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If PO-based casings are used to achieve high recyclability, then the ease of recycling is improved, but the stiffness and water vapor barrier deteriorate leading to wrinkles

Engineering Contradiction:

ImproverecyclabilityVSAvoidstiffness

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The invention merges PO-based recyclable structures with PA-based stiffness-providing layers in multi-layer configurations. The PO layers maintain recyclability while PA layers provide the necessary stiffness and strength, creating a hybrid structure that achieves both goals simultaneously

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP4684953A1Recyclable polyolefin-based plastic casing for cooked sausages

Publication Date: 2026.01.28 VISCOFAN CZ SRO

Figure 1~4

AI summary

The present invention provides a recyclable multi-layered coextruded bi-axially oriented thermoplastic food casing characterized by a high polyolefin content, two skin layers essentially of the same polyolefin type, a non-skin layer with a component, having a density greater than 1,00 g/cm3, an overall density of less than 1,00 g/cm3 and a ratio of stiffness in transversal direction to stiffness in machine direction of more than 1, where the high stiffness is obtained without radiation/crosslinking. The casing yields wrinkle-free sausages.