Multilayer Polyamide-Polyolefin Film Gussetability
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Solution Overview
Problem
Existing multilayer films used in FIBC liners face challenges with gussetability and flex crack resistance, particularly in the thickness range of 50-200 microns, which affects production efficiency and the integrity of the packaging.
Innovation Solution
A multilayer film construction comprising a polyolefin polymer with an outer layer made of a blend of two or more polyamides, including polyamide-based slip and/or anti-block additives, and an inner layer comprising a blend of ethylene alpha-olefin copolymers and polyether copolymers, which enhances gussetability and flex crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high barrier materials such as EVOH or polyamide are used to improve oxygen barrier properties, then oxygen impermeability is improved, but gussetability deteriorates because these materials are stiffer than polyolefins
Solution Approach 1:
The patent uses a multilayer film construction combining polyolefin layers with polyamide/EVOH barrier layers. The polyolefin layers provide flexibility and gussetability, while the barrier layers provide oxygen impermeability. This composite structure resolves the contradiction by distributing different functional requirements across multiple material layers.
Solution Approach 2:
Different regions of the film have different material compositions optimized for their specific functions. The barrier layers are positioned where oxygen protection is needed, while polyolefin layers are positioned where flexibility and gusset formation are required. This local optimization allows the film to simultaneously achieve both oxygen barrier properties and gussetability.
2Reliability
If polyamide layers are used to improve oxygen barrier properties, then oxygen impermeability is improved, but flex crack resistance deteriorates because polyamides have much worse flex crack properties than polyolefins
Solution Approach 1:
The multilayer construction combines polyolefin layers with superior flex crack resistance with polyamide barrier layers. The polyolefin layers act as a protective matrix that prevents flex cracking, while the polyamide layers provide oxygen barrier properties. This composite approach allows the film to achieve both oxygen impermeability and flex crack resistance simultaneously.
Solution Approach 2:
The polyolefin layers are positioned to provide prior cushioning and protection against flex-induced stresses before they can reach the more brittle polyamide barrier layers. This protective positioning prevents flex cracks from developing in the polyamide layers, thereby maintaining both oxygen barrier properties and flex crack resistance.
3Reliability
If film thickness is increased to improve mechanical strength and barrier properties, then oxygen barrier properties and flex crack resistance are improved, but gussetability deteriorates due to reduced pliability
Solution Approach 1:
The multilayer film uses a composite structure where thin polyolefin layers provide flexibility and gussetability, while thin polyamide/EVOH layers provide oxygen barrier properties. This eliminates the need for increased overall thickness to achieve both mechanical strength and barrier properties, thereby maintaining gussetability even at 50-200 microns total thickness.
Data Source
AI summary
The invention relates to plastic film with average thickness of 50 to 200 microns, comprising polyamides and polyolefins.