Co-extruded Oriented Film with Crystalline Tie Layer for High Seal Strength
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Solution Overview
Problem
Current co-extruded biaxially oriented polypropylene (BOPP) films used in food packaging have poor heat seal performance due to lack of seal strength, limiting their use to small, lightweight, and non-high-seal-strength applications, necessitating a high heat seal strength oriented film to replace traditional laminated structures and eliminate the adhesive lamination process.
Innovation Solution
A multilayered film comprising a first layer, a second layer, and a tie layer with a crystalline block composite, where the tie layer is disposed between the first and second layers, comprising crystalline ethylene-based and alpha-olefin-based polymers and block copolymers, enhancing interlayer adhesion and seal strength through biaxial orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If co-extruded BOPP films are used to replace laminated structures, then manufacturing complexity is reduced and production costs are lowered, but heat seal strength is insufficient
Solution Approach 1:
The patent applies composite materials by creating a multilayer film structure where a polypropylene layer is combined with a polyethylene layer containing a specific elastomer. This composite structure allows the film to achieve both the manufacturing simplicity of co-extrusion and the heat seal strength of traditional laminated structures, as the polyethylene/elastomer combination provides superior sealing performance while maintaining structural integrity.
Solution Approach 2:
The patent utilizes parameter changes by carefully controlling the elastomer content (5-50 parts by weight per 100 parts polyethylene) and the molecular weight ratio between polypropylene and polyethylene. By optimizing these parameters, the film achieves adequate heat seal strength while maintaining the benefits of co-extruded oriented film manufacturing.
2Strength
If adhesive lamination is used to achieve high seal strength, then heat seal performance is improved, but manufacturing complexity and production costs increase
Solution Approach 1:
The patent merges the sealing function and the structural function into a single multilayer film. The polyethylene layer containing elastomer serves both as the sealant layer and as part of the structural film, eliminating the need for separate adhesive lamination processes. This integration achieves high heat seal strength while simplifying manufacturing to a single co-extrusion and orientation process.
Solution Approach 2:
The elastomer acts as an intermediary component that enables the polyethylene to bond effectively with the polypropylene layer while maintaining heat sealability. The specific elastomer (with glass transition temperature of -50°C to -100°C) mediates between the rigid polypropylene structure and the sealing requirements, providing both adhesion and seal strength without requiring external adhesives.
3Productivity
If co-extruded oriented film is used for packaging, then production efficiency is improved, but seal strength is insufficient for high-value applications
Solution Approach 1:
The patent creates a composite material system combining polypropylene with a polyethylene-elastomer blend in a co-extruded oriented film. This composite structure maintains the high production efficiency of co-extrusion processes while achieving seal strengths sufficient for high-value food packaging applications through the synergistic properties of the polymer blend.
Solution Approach 2:
The patent optimizes critical parameters including the polyethylene to elastomer ratio (5-50:100 by weight), the molecular weight relationship between polypropylene and polyethylene, and the orientation conditions. These parameter adjustments enable the film to achieve high seal strength (adequate for vertical seal tests) while maintaining efficient co-extruded oriented film production rates.
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 multilayered film achieves high heat seal strength, improved mechanical properties, and optical clarity, enabling effective food packaging while reducing production costs by eliminating the need for adhesive lamination.
Implementation Method 1
where the multilayered film is biaxially oriented
Implementation Method 2
the tie layer comprises a crystalline block composite and where the tie layer is disposed between the first layer and the second layer
Data Source
Figure 1
AI summary
Disclosed herein is a multilayered film comprising a first layer and a second layer; and a tie layer; where the tie layer comprises a crystalline block composite and where the tie layer is disposed between the first layer and the second layer; the first layer being disposed on a first surface of the tie layer; the second layer being disposed on a second surface of the tie layer; where the second surface is opposedly disposed to the first surface; where the multilayered film is biaxially oriented. Disclosed herein too is a method of manufacturing the aforementioned multilayer film.