Multilayer LLDPE Film Segmentation for Seal Strength
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Solution Overview
Problem
Cast or blown unoriented polyethylene and polypropylene films used as sealants in packaging have mediocre physical properties, requiring combination with other materials for enhanced barrier protection and print quality, which increases film thickness and manufacturing costs.
Innovation Solution
Development of multilayer films with a core layer, optional tie layers, and sealant layers, including metallized and polymer-coated layers, to achieve high seal strengths and hermetic seals at reduced thickness, while maintaining performance and reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unoriented polyethylene or polypropylene films are used as sealants, then they provide basic sealing function, but they have mediocre physical properties requiring combination with other materials
Solution Approach 1:
The film is divided into multiple functional layers: a sealant layer (5-20 microns) containing polyethylene or polypropylene for sealing, a core layer (20-80 microns) providing structural support and barrier properties, and optional skin layers for surface properties. Each layer performs a specific function, allowing the sealant to be thin and specialized while the core provides overall film integrity.
Solution Approach 2:
The invention uses composite film structures combining different polymers (polyethylene, polypropylene, polyester, nylon) in specific layers. The sealant layer uses thermoplastic polymers for sealing, while the core layer may use polyester or nylon for barrier and mechanical properties, creating a composite material that achieves both sealing performance and structural requirements.
2Reliability
If films are combined with other web materials for enhanced barrier protection and rigidity, then performance is improved, but film thickness and manufacturing cost increase
Solution Approach 1:
Different layers of the film have different thicknesses and properties optimized for their specific functions. The sealant layer is thin (5-20 microns) as it only needs to provide sealing, while the core layer is thicker (20-80 microns) to provide barrier and structural properties. This local optimization reduces overall thickness compared to uniform thick films.
Solution Approach 2:
The invention transitions from considering only film thickness as the parameter for performance to using a multi-dimensional approach with multiple layers of different materials and thicknesses. This allows achieving barrier protection through material selection and layer configuration rather than simply increasing overall thickness.
3Reliability
If films are combined with other web materials to enhance physical properties, then sealing and barrier performance is improved, but manufacturing cost increases
Solution Approach 1:
The invention optimizes the thickness parameters of each layer to achieve the minimum necessary for performance. The sealant layer is kept thin (5-20 microns) since it only needs to provide sealing, reducing polymer consumption. The overall film structure is designed to use the least amount of expensive barrier materials (nylon, polyester) necessary to achieve required performance.
Data Source
AI summary
Disclosed are compositions, methods, and uses for multi-layered films which are intended to provide high quality sealants having sufficient sealing strength for use in packaging and other applications while being more cost-effective and higher-yield than traditional combinations of unoriented polyolefin films and web materials. The film comprises a multilayer structure of LLDPE having a core layer, a surface skin layer, and a sealant skin layer. The core layer further comprises a slip agent, while the skin layers further comprise antiblock agents. Optional embodiments may include tie layers between the core layer and the skin layers, or may include pigments in one or more of the core layer or tie layers. The surface skin layer may be subjected to a surface treatment (e.g., corona treatment) to improve suitability for coating or metallization.