Heat Sealing Laminate with Acid-Modified Polyolefin Layers
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Solution Overview
Problem
Films made from ethylene-vinyl alcohol copolymer (EVOH) used in packaging suffer from inferior impact resistance, bending fatigue resistance, stretchability, thermoformability, adhesiveness, and sealant aptitude, and are prone to dimensional changes and wrinkle formation in humid environments, leading to defective adhesion and reduced sealing strength when laminated with other substrates.
Innovation Solution
A laminate for heat sealing comprising a non-adsorbing layer with ethylene-vinyl alcohol copolymer and acid-modified polyolefin, and a non-swelling layer with polyolefin and acid-modified polyolefin, where the non-swelling layer contains 20% to 60% by weight of acid-modified polyolefin, is developed to prevent dimensional changes and maintain non-adsorbing properties in humid environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVOH film is used for packaging, then gas impermeability and aroma retention are improved, but dimensional stability in humid environments deteriorates
Solution Approach 1:
The invention uses a composite structure consisting of an EVOH layer (7-20 μm) laminated between two polyolefin layers (15-30 μm each). The polyolefin layers act as barrier layers that prevent moisture from reaching the EVOH layer, thereby preventing dimensional changes while maintaining the gas impermeability of the EVOH layer.
Solution Approach 2:
The polyolefin layers serve as intermediary barrier layers that mediate between the external humid environment and the EVOH layer. These layers absorb or block moisture, preventing it from interacting with the EVOH layer, thus protecting the EVOH from dimensional changes while allowing the EVOH to maintain its gas barrier properties.
2Reliability
If EVOH film is used for packaging, then aroma retention is improved, but adhesion to substrates deteriorates
Solution Approach 1:
The invention creates a composite laminate where the polyolefin layers provide adhesion to external substrates (such as aluminum foil or other packaging materials), while the EVOH layer maintains its aroma retention properties. The polyolefin acts as an adhesive interface between the EVOH and external materials.
Solution Approach 2:
The polyolefin layers function as intermediary adhesion layers that mediate between the EVOH layer and external substrates. They provide the necessary adhesion strength for lamination while allowing the EVOH layer to maintain its non-adsorbing properties for aroma retention.
3Reliability
If EVOH film is used for packaging, then gas impermeability is improved, but sealant aptitude deteriorates
Solution Approach 1:
The invention structures the laminate with sealable polyolefin layers on the outer surfaces, which provide good sealant aptitude for heat sealing operations. The EVOH layer remains in the middle to provide gas impermeability, while the polyolefin seal layers facilitate easy sealing without compromising the barrier properties.
Data Source
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AI summary
The present invention provides a film which has non-adsorbing properties equivalent to those of an ethylene-vinyl alcohol copolymer film, and which does not undergo a dimensional change in a humid environment. A laminate for heat sealing according to the present invention provided with: a non-adsorbing layer containing an ethylene-vinyl alcohol copolymer and an acid-modified polyolefin, and a non-swelling layer laminated on the non-adsorbing layer and containing a polyolefin and/or an acid-modified polyolefin.