Polyolefin Retort Laminate With Controlled Heat Shrinkage
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Solution Overview
Problem
Existing laminates using polyolefin-based films are unable to withstand high-temperature retort treatment, necessitating the development of a laminate capable of withstanding such conditions while composed mainly of a single material.
Innovation Solution
A laminate comprising polyolefin films with inorganic oxide layers and specific heat shrinkage rates, including a first and second base material layer and a sealant layer, where the second base material layer's heat shrinkage rate is greater than or equal to the first and sealant layer's, ensuring stability during high-temperature retort treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laminate is prepared using a polyolefin-based film to achieve formation of a laminate from a single material, then recyclability and environmental performance are improved, but the packaging bag cannot withstand high-temperature retort treatment
Solution Approach 1:
The invention changes the physical and chemical parameters of the polyolefin film by controlling its molecular weight distribution (specifically using a film with a weight average molecular weight of 50,000 or more and a polydispersity index of 2.0 or more), adding specific additives (antioxidants, nucleating agents), and controlling crystallinity to achieve both recyclability and high-temperature retort resistance
Solution Approach 2:
The invention creates a composite structure by incorporating inorganic oxide layers (such as silicon oxide, aluminum oxide) on the polyolefin film surfaces, combining organic polyolefin material with inorganic oxide to enhance heat resistance while maintaining the single-material polyolefin base for recyclability
2Stability of the object's composition
If the heat shrinkage rate of the second base material layer is controlled to be greater than or equal to the first and sealant layer to ensure stability during retort, then structural integrity at high temperature is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention systematically adjusts multiple parameters including the molecular weight distribution of the polyolefin, the type and concentration of additives (nucleating agents at 0.01-1.0 wt%, antioxidants at 0.1-5.0 wt%), and the crystallinity structure to achieve the desired heat shrinkage rate relationship between layers, thereby obtaining both dimensional stability and manageable manufacturing precision
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 laminate maintains gas barrier performance and structural integrity during high-temperature retort treatment, enabling the formation of packaging bags suitable for retort pouch applications.
Implementation Method 1
the polyolefin film of the first base material layer or the second base material layer includes an inorganic oxide layer on at least one surface thereof
Implementation Method 2
each of the first base material layer, the second base material layer, and the sealant layer has a heat shrinkage rate, in a travel direction (MD direction) after heating at 120° C. for 15 minutes
Data Source
AI summary
A laminate including a first base material layer, a second base material layer, and a sealant layer in this order, wherein all three layers include a polyolefin film; the polyolefin film of the first base material layer or the second base material layer includes an inorganic oxide layer on at least one surface thereof; and each of the first base material layer, the second base material layer, and the sealant layer has a heat shrinkage rate, in a travel direction after heating at 120° C. for 15 minutes, which satisfies the following inequalities: heat shrinkage rate of the second base material layer≤5% (Inequality 1); heat shrinkage rate of the second base material layer≥heat shrinkage rate of the first base material layer (Inequality 2); and, heat shrinkage rate of the second base material layer≥heat shrinkage rate of the sealant layer (Inequality 3).