Polyolefin Film Composite with Polyurethane Equalization Layer
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Solution Overview
Problem
Existing film composites for flexible packaging face challenges in achieving a cost-effective, high-quality optical appearance with a low proportion of other polymers, as they often have low flex-crack resistance and issues with ink adhesion and contamination due to uneven barrier layers, particularly when using aluminum oxide or silicon oxide coatings, and require additional adhesion-imparting layers with ethylene vinyl alcohol copolymers.
Innovation Solution
A film composite with a cover film made of polyolefin and a barrier layer, featuring an equalization layer of hardened polyurethane between the cover film and the barrier layer, which can be formed from polyvinyl alcohol or acrylate-based materials, to create a continuous and thin barrier effect while protecting the imprinting from fat migration, and incorporating solid particles in the equalization layer for enhanced barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum oxide or silicon oxide coating is applied to create a fat barrier, then the barrier effect is improved, but the flex-crack resistance deteriorates due to extreme stiffness of the coating materials
Solution Approach 1:
The patent introduces an intermediary layer between the polyolefin cover film and the aluminum oxide/silicon oxide barrier layer. This intermediate layer acts as a buffer that absorbs stress and prevents direct transmission of mechanical stresses from the flexible cover film to the brittle barrier layer, thereby preventing flex-cracks while maintaining the barrier effect.
Solution Approach 2:
The patent creates a composite structure consisting of multiple layers with different properties: a flexible polyolefin cover film, an intermediate stress-absorbing layer, and a rigid barrier layer. This composite material approach combines the advantages of each layer while compensating for their individual weaknesses, achieving both flexibility and barrier performance.
2Duration of action of stationary object
If barrier layers are applied to protect packaged goods, then the shelf life is improved, but the optical quality deteriorates due to fat migration contaminating the imprinting
Solution Approach 1:
The intermediate layer serves as a protective mediator between the barrier layer and the imprinting. It prevents direct contact between migrating fat and the ink layers, thereby maintaining optical quality while the barrier layer continues to prevent fat migration for extended shelf life.
Solution Approach 2:
The patent segments the packaging structure into distinct functional layers: the cover film with imprinting, an intermediate protective layer, and the barrier layer. This segmentation allows each layer to perform its specific function independently, with the intermediate layer specifically tasked with protecting the imprinting from fat contamination.
3Reliability
If EVOH is used as a barrier layer, then the barrier effect is improved, but the device complexity increases due to incompatibility with polyolefins requiring additional adhesion-imparting layers
Solution Approach 1:
The patent uses an intermediate layer as a mediator that ensures compatibility and adhesion between the polyolefin cover film and the EVOH barrier layer. This single intermediate layer provides both adhesion functionality and stress management, eliminating the need for multiple separate adhesion-imparting layers and simplifying the overall structure.
4Reliability
If a thick barrier layer is applied to ensure complete protection, then the barrier effect is improved, but the loss of substance increases due to higher proportion of other polymers
Solution Approach 1:
The intermediate layer enables the use of a thinner barrier layer by providing stress absorption and adhesion. This reduces the total amount of non-polyolefin materials needed while maintaining effective barrier protection, thereby minimizing the proportion of other polymers in the overall structure.
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 solution allows for a cost-effective, high-quality optical appearance with a minimal proportion of other polymers, maintaining the barrier effect and preventing ink contamination, while enabling complete recyclability by keeping the barrier and equalization layers thin and ensuring a continuous barrier layer despite uneven surfaces caused by imprinting.
Implementation Method 1
The use of the invention makes it possible to avoid flex-cracks in the barrier layer, as compared with embodiments in which the cover film is directly coated with the barrier layer
Implementation Method 2
it is also possible to achieve what is called a fat barrier using such barrier layers, which prevents the fat contained in the packaged goods from migrating through the packaging
Implementation Method 3
the unevenness of which, in particular due to the imprinting, makes it difficult to apply a thin barrier layer in a manner sorted by type
Data Source
AI summary
A film composite for film packaging, having a cover film composed of a polyolefin and a barrier layer, wherein the cover film has an imprinting, at least in part, on a side that faces the barrier layer. An equalization layer is arranged between the cover film and the barrier layer, which layer borders, at least in part, on the imprinting, wherein the equalization layer is formed from a hardened material on the basis of polyurethane.