MDO Multilayer Film Sealant Layer Design
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Solution Overview
Problem
Machine direction oriented (MDO) polyethylene films experience significant loss of sealing performance and reduced temperature resistance, leading to a narrow sealing window, making it challenging to manufacture articles requiring heat sealing.
Innovation Solution
A multilayer structure comprising a MDO film with a metal layer, a first layer extruded onto the metal layer, and a sealant layer in adhering contact, where the first layer includes an interpolymer of ethylene and acrylic acid or methacrylic acid, and the sealant layer has a heat seal initiation temperature of 95°C or less, allowing for reduced sealing temperatures and broader sealing windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If MDO polyethylene films are used to achieve orientation and mechanical properties, then sealing performance is significantly lost and temperature resistance is reduced, but this results in a very narrow sealing window and manufacturing challenges
Solution Approach 1:
The film is divided into multiple functional layers: an MDO polyethylene layer providing mechanical strength and orientation, and a separate sealant layer providing sealing capability. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between maintaining MDO structural integrity and achieving reliable sealing performance
Solution Approach 2:
The invention uses a composite structure combining MDO polyethylene film with a sealant layer having complementary properties. The sealant layer is specifically selected or formulated to have appropriate melt temperature and sealing characteristics that the MDO polyethylene layer lacks, creating a composite material system that achieves both mechanical strength and sealing performance
2Reliability
If sealing temperature is increased to compensate for MDO film degradation, then sealing performance improves, but degradation and burning of other layers increases
Solution Approach 1:
The sealant layer acts as an intermediary between the heat source and the MDO polyethylene layers. It is specifically designed to melt and seal at a lower temperature than the MDO layers would degrade, thereby mediating the sealing process to protect the structural layers from thermal damage while still achieving reliable seals
Solution Approach 2:
The invention changes the thermal parameters of the sealing system by introducing a sealant layer with a lower melt temperature and appropriate sealing characteristics. This parameter change allows sealing to occur at temperatures that prevent degradation of the MDO polyethylene structure, resolving the contradiction between sealing reliability and thermal damage
3Adaptability or versatility
If a sealant layer with low seal initiation temperature is added, then sealing window broadens and degradation is reduced, but device complexity increases
Solution Approach 1:
The sealing function is segmented into a dedicated sealant layer that can be independently selected and optimized. This layer is specifically chosen for its low seal initiation temperature and appropriate rheological properties, allowing the rest of the MDO structure to maintain its structural integrity while achieving broad sealing window adaptability
Solution Approach 2:
The sealant layer serves multiple functions: it provides the primary sealing interface, protects underlying layers from thermal degradation, and broadens the sealing window. This multi-functionality justifies the added layer complexity by consolidating multiple benefits into a single component
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
This configuration enables consistent sealing at lower temperatures, reducing degradation of the multilayer structure and expanding the sealing and shrinkage range, thereby improving manufacturing efficiency and product integrity.
Implementation Method 1
the sealant layers of both films are in contact with each other, the seal bars contact and heat the outer layers of the films. The heat is transferred through the outer layers of the films to the inner sealant layers which seal to one another
Implementation Method 2
The interpolymer may have a melt index (I2) of 5 to 20 g/10 minutes, an acid content of 1 to 10 weight percent and a melting temperature of 90° C. to 100° C.
Data Source
AI summary
In one embodiment, a multilayer structure may include a machine direction oriented (MDO) multilayer film, a first layer, and a sealant layer. The MDO multilayer film may include (i) a metal layer and (ii) an inner layer. The inner layer may include EVOH: PVOH: or a blend of polyethylene and an interpolymer of ethylene and methyl acrylate, ethyl acrylate, or carboxylic acid. The first layer may be extruded onto the metal layer. The first layer may include an interpolymer of ethylene and acry lic acid or methacrylic acid. The interpolymer may have a melt index (12) of 5 to 20 g/10 minutes. an acid content of 1 to 10 weight percent and a melting temperature of 90° C. to 100° C. The sealant layer may include a polyethylene having a melt index (I2) of 3 to 30 g/10 minutes and a heat seal initiation temperature of 95° C. or less.