Multilayer Insulating Film Structure for PP-PE Layer Adhesion
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Solution Overview
Problem
Existing insulating films for electrical devices face challenges in achieving good adhesion between layers while maintaining thermal properties and flame retardance, especially when using polypropylene as the outer layer.
Innovation Solution
A multilayer film structure is developed with a polypropylene layer containing an ethylene acrylate/alkylacrylate copolymer, co-extruded with a polyethylene layer to enhance adhesion and improve thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polypropylene outer layer is used to provide excellent mechanical and electrical properties, then insulation performance is improved, but adhesion to the inner polyethylene layer deteriorates
Solution Approach 1:
The invention introduces a polar comonomer layer (ethylene copolymer with carboxylic acid groups) only at the interface between the polypropylene outer layer and polyethylene inner layer. This localized modification provides adhesion promotion exactly where needed, without compromising the excellent insulation properties of the bulk polypropylene material.
Solution Approach 2:
The polar comonomer layer acts as an intermediary between the polypropylene and polyethylene layers. It contains carboxylic acid groups that can form hydrogen bonds with both the polypropylene and polyethylene, thereby mediating the adhesion between these two otherwise incompatible polymers.
2Ease of operation
If a softer inner layer is added to prevent damage to the electrical device, then mechanical protection is improved, but adhesion between layers becomes more difficult to achieve
Solution Approach 1:
The softer inner layer (polyethylene) is used only for mechanical protection, while the adhesion promotion is localized at the interfaces through the polar comonomer incorporation. This allows the soft layer to provide cushioning without creating adhesion problems throughout the entire structure.
Solution Approach 2:
The invention creates a composite multilayer structure combining polypropylene, polyethylene, and a polar comonomer-containing ethylene copolymer. This composite approach allows each material to contribute its specific properties (mechanical strength, softness, adhesion) while working together as an integrated system.
3Strength
If adhesion promoters are added to improve layer bonding, then adhesion is improved, but thermal properties and flame retardance may be compromised
Solution Approach 1:
The adhesion promotion is achieved locally at the layer interfaces through polar comonomer incorporation, rather than throughout the entire film structure. This allows the bulk material to maintain its excellent thermal and flame retardant properties while the interfaces provide enhanced bonding.
Solution Approach 2:
The invention modifies the chemical parameters (introducing carboxylic acid groups through polar comonomers) only in specific regions (the outer layer adjacent to the inner layer) to achieve adhesion, while maintaining the physical and thermal parameters of the bulk polypropylene material.
Data Source
AI summary
A film that comprises, in the given order, the following layers: a) one or more first layer(s) (A) comprising a polyolefin composition (PCI) comprising: i) a polypropylene (PP1); and ii) an ethylene polymer (PE1) comprising monomer units of ethylene and one or more polar comonomer units selected from the group consisting of (C1-C6)-alkyl acrylate and (C1-C6)-alkyl (C1-C6)-alkylacrylate comonomer units, b) a second layer (B) comprising a polyethylene composition (PC2), wherein a surface of the second layer (B) is in adherent contact with a surface of one of the first layer(s) (A).