Composite Polymeric Film Heat-Sealable Coating for Polyolefin Containers
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Solution Overview
Problem
Conventional polyester lidding films exhibit low heat-seal strength with polyolefin containers, such as polypropylene or polyethylene, and fail to provide a clean peel, which is essential for maintaining food quality and hygiene, and also lack optimal optical properties for clarity and freshness perception.
Innovation Solution
A heat-sealable composite film with a biaxially oriented polyester substrate coated with a heat-sealable layer comprising a styrenic linear block copolymer thermoplastic elastomer, ethylene vinyl acetate (EVA) copolymer, and a tackifying resin, where the EVA copolymer is present in specific weight percentages to enhance sealability, peelability, and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyester lidding films are used, then the film structure is simple and cost-effective, but the heat-seal strength with polyolefin containers is low
Solution Approach 1:
The patent applies composite materials by creating a multi-layer film structure consisting of a polyester substrate layer and a heat-sealable polymeric coating layer. The coating layer contains specific components (styrenic linear block copolymer thermoplastic elastomer, EVA copolymer, and tackifying resin) in controlled ratios to achieve strong adhesion to polyolefin containers while maintaining structural integrity.
2Ease of operation
If conventional heat-sealable coatings are applied, then the sealing function is achieved, but clean peelability is not achieved
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of the coating layer components: styrenic linear block copolymer thermoplastic elastomer (25-35 wt%), EVA copolymer (25-35 wt%), and tackifying resin (30-50 wt%). This specific parameter control enables the coating to achieve optimal balance between adhesion strength and clean peelability, preventing residue formation on the container surface.
3Strength
If the heat-sealable layer composition is optimized for sealability, then adhesion to polyolefin improves, but optical clarity deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the total thickness of the heat-sealable coating layer to be between 1-10 micrometers and controlling the molecular weight and composition of the EVA copolymer (vinyl acetate content of 10-40%). These parameter adjustments ensure that the coating provides sufficient adhesion strength while remaining thin and transparent to maintain optical clarity for consumer perception of food quality.
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 achieves strong heat-seal strength and clean peelability on polyolefin containers while maintaining high optical clarity, ensuring food quality and consumer perception of freshness and hygiene.
Implementation Method 1
This seal is formed by placing the lid on top of the container and applying heat and pressure in order to soften or melt the sealable coating layer so that it adheres to the surface of the container
Implementation Method 2
Biaxially oriented polyester film has been widely used as a flexible substrate for lidding films because of its excellent mechanical strength
Data Source
AI summary
A heat-sealable composite film comprising an oriented polyester substrate layer having a first and second surface is provided. Disposed on the first surface of the substrate layer is a heat- sealable polymeric coating layer comprising a styrenic linear block copolymer thermoplastic elastomer, an ethylene vinyl acetate (EVA) copolymer and a tackifying resin. Also described is a sealed container comprising a receptacle containing a food product, and a lid formed from said heat-sealable composite film.