Multi-segment Heat-shrinkable Film for Meat Packaging
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Solution Overview
Problem
Conventional multi-segment heat-shrinkable films used for packaging fresh foods, particularly bone-in meat, face challenges in achieving high degrees of free shrink and tight fit due to limitations in oxygen barrier materials and puncture resistance, especially when exposed to ionizing radiation.
Innovation Solution
A multi-segment film structure comprising a bulk layer and a microlayer section with a high ratio of microlayer thickness to bulk layer thickness, combined with an oxygen barrier segment, is developed to enhance free shrink and compression, achieved through a coextrusion process and orientation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ionizing radiation is used to induce cross-linking for puncture resistance, then film strength improves, but oxygen-barrier materials degrade
Solution Approach 1:
The film is divided into multiple segments with distinct functions: a first segment containing cross-linkable polymer for puncture resistance, and a second segment containing oxygen-barrier material. This segmentation allows each segment to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different regions of the film have different properties: the first segment is designed for mechanical strength and cross-linking, while the second segment is designed for oxygen barrier performance. This local differentiation resolves the contradiction by assigning specific qualities to specific locations.
2Shape
If multi-segment films are oriented to achieve high compression, then tight fit improves, but free shrink degree decreases
Solution Approach 1:
The patent optimizes the thickness ratio parameter of microlayers to bulk layers (at least 1:2) and the number of microlayers (at least 10) to achieve a balance between compression and free shrink. By changing these structural parameters, the film achieves both tight fit and adequate shrinkage.
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 a total free shrink of at least 30% at 85°C, providing a tighter package and minimizing meat purge, while maintaining an oxygen transmission rate below 100 cc/m²-atm-24 hrs, thus addressing the need for improved packaging films.
Implementation Method 1
which have been heated to their flow or melting point from an extrusion or coextrusion die
Implementation Method 2
An oriented (i.e., heat-shrinkable) material will tend to return to its original unstretched (unextended) dimensions when heated to an appropriate elevated temperature
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A multi-segment, heat-shhnkable film includes a first segment and a second segment. The first segment includes a bulk layer and a microlayer section comprising a plurality of microlayers. The second segment is joined to the first segment and has an oxygen transmission rate of no more than about 100 cc/m2-atm.-24 hrs. (at 73°F and 0% relative humidity). The multi-segment film has a total free shrink (ASTM D2732-08) of at least about 30% at 185°F.