Polyethylene Film Surface Geometry for Blocking Resistance
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Solution Overview
Problem
Conventional polyethylene films experience blocking issues during unwinding and lamination, leading to poor slipperiness and impaired heat sealing properties at low temperatures, which are not adequately addressed by existing solutions.
Innovation Solution
A polyethylene film with a specific layer structure and resin composition, including a sealing layer, intermediate layer, and laminating layer, where the arithmetic mean inclination angles of the film surfaces are optimized to reduce contact area and enhance slipperiness, using a blend of polyethylene and polypropylene resins with controlled melt flow rates and densities, along with the addition of anti-blocking agents and organic lubricants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealant material is laminated with a base material to improve heat sealing property, then heat sealing property is improved, but blocking occurs between the sealant material and base material after storage
Solution Approach 1:
The invention applies different surface treatments to different regions of the film. The sealant layer is given specific surface properties (arithmetic mean inclination angle of 0.3-1.5°) to prevent blocking, while the base material layers maintain their structural functions. This localized surface engineering allows the sealant to resist blocking without compromising the overall lamination structure and heat sealing performance.
Solution Approach 2:
The invention changes the surface geometry parameters of the sealant layer by controlling the arithmetic mean inclination angle within a specific range (0.3-1.5°). This parameter optimization reduces the contact area between laminated films, thereby preventing blocking while maintaining effective heat sealing contact when needed.
2Object-generated harmful factors
If powder of starch or like is dusted on the film surface to prevent blocking, then blocking resistance is improved, but appearance of packed foods is impaired and heat sealing strength deteriorates
Solution Approach 1:
The invention replaces the chemical/mechanical approach of dusting powder with a physical surface geometry approach. By controlling the arithmetic mean inclination angle of the sealant layer surface, blocking resistance is achieved through reduced contact area rather than through powder coatings, thereby maintaining both heat sealing strength and food appearance.
3Reliability
If polyethylene film is used to provide good heat sealing property, then heat sealing property is improved, but blocking resistance in unwinding the film roll is insufficient
Solution Approach 1:
The invention applies specific surface geometry characteristics to the sealant layer (arithmetic mean inclination angle of 0.3-1.5°) while maintaining the bulk polyethylene material properties for heat sealing. This localized surface treatment provides blocking resistance during unwinding without compromising the heat sealing functionality of the polyethylene film.
Solution Approach 2:
The invention optimizes the surface geometry parameter (arithmetic mean inclination angle) of the sealant layer within a specific range to reduce inter-film adhesion during storage and unwinding, while maintaining the material's inherent heat sealing properties.
Data Source
AI summary
Provided is a polyethylene film that is more excellent in blocking in unwinding the film in the film roll state, and more excellent in blocking between sealants after lamination with a base material, and also having transparency and excellent heat sealing property even at low temperatures. A polyethylene film wherein in at least either face, a ratio between an arithmetic mean inclination angle in a machine direction of film (RΔa (MD) [°]), and an arithmetic mean inclination angle in a direction perpendicular to the machine direction (RΔa (TD) [°]) satisfies the following formula (1):1.2≤RΔa(TD)/RΔa(MD)≤3.6 (1)(RΔa (MD): arithmetic mean inclination angle measured in the machine direction of film, and RΔa (TD): arithmetic mean inclination angle measured in the direction perpendicular to the machine direction of film).