Polyester Film Surface Microprotrusions for Static-Mark-Free Coating
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Solution Overview
Problem
Conventional biaxially oriented polyester films face issues with static marks and static mark discharge traces during secondary processing, leading to non-uniform thin layer formation and increased wrinkle generation in film rolls, along with insufficient gas barrier performance and adhesion problems.
Innovation Solution
A biaxially oriented polyester film with controlled surface microprotrusions, having specific number and height ranges, along with controlled kinetic and static friction coefficients, to prevent static marks and improve slipperiness, thereby facilitating smooth secondary processing and gas barrier performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the surface of biaxially oriented polyester film is made smooth to improve transparency, then transparency is improved, but static marks and static mark discharge traces increase during secondary processing
Solution Approach 1:
The patent applies local quality by creating micro protrusions (3-50 nm height) at specific locations on the film surface while maintaining overall surface smoothness. These localized micro-structures reduce static electricity accumulation without significantly impacting overall transparency, resolving the contradiction between smooth surface requirements and static mark prevention.
Solution Approach 2:
The patent changes the surface morphology parameters by controlling the height (3-50 nm) and density (200-600 per 4×10^-12 m²) of micro protrusions. This parameter optimization reduces static electricity generation while maintaining transparency, addressing both requirements simultaneously.
2Object-generated harmful factors
If the number of micro protrusions is increased to reduce static marks, then static mark reduction is improved, but wrinkle generation in film rolls increases
Solution Approach 1:
The patent optimizes the parameter range of micro protrusion height (3-50 nm) and density (200-600 per 4×10^-12 m²) to achieve the right balance. This controlled parameter adjustment reduces static marks while preventing excessive wrinkle formation, as the micro protrusions are small enough not to cause macroscopic wrinkling during film rolling.
Solution Approach 2:
The patent applies partial action by introducing only a controlled number of micro protrusions (200-600 per unit area) rather than maximizing their quantity. This partial application is sufficient to reduce static marks but does not excessive enough to cause wrinkle problems, achieving the optimal balance.
3Ease of operation
If the film surface is made smoother to improve adhesion during secondary processing, then adhesion is improved, but gas barrier performance deteriorates
Solution Approach 1:
The micro protrusions create localized surface features that enhance adhesion through increased surface area and mechanical interlocking, while the overall film structure remains intact to maintain gas barrier performance. The localized nature of protrusions means the bulk film's barrier properties are preserved.
Solution Approach 2:
The patent creates a composite surface structure combining the base polyester film with micro protrusion features. This composite surface morphology provides both adhesion enhancement through increased surface area and maintains gas barrier integrity through the continuous film matrix, resolving the contradiction between adhesion and barrier performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The film exhibits reduced wrinkle formation, enhanced transparency, and improved gas barrier performance during secondary processing, such as coating and vapor deposition, while maintaining film integrity and reducing adhesion issues.
Implementation Method 1
since a biaxially oriented polyester film has electrical insulating properties, static marks, which are parts that is partially charged by peeling or contacting with a conveyer roll in a film producing process or secondary processing process, and static mark discharge traces resulting from discharging of built-up static electricity etc. are easily generated
Implementation Method 2
a prescribed range of the number and the shape of micro protrusions having a prescribed height or higher can improve slipperiness between films
Implementation Method 3
vapor-deposited polyester films having metal oxide on the film surface have been widely used thanks to its superiority in heat resistance and transparency as well as gas barrier performance
Data Source
AI summary
Disclosed is a biaxially oriented polyester film that is superior in transparency and easy to perform secondary processing such as coating and vapor deposition, and satisfies performance after the secondary processing. The biaxially oriented polyester film consists of a polyester resin composition including particles, and at least one surface of the film satisfies all of the following requirements (1) to (3): (1) the number of micro protrusions having a height of less than 3 nm per an area of 4×10−12 m2 of 250 or more and 600 or less; (2) the number of micro protrusions having a height of 3 nm or more per an area of 4×10−12 m2 of 300 or more and 600 or less; and (3) an arithmetic average height Sa of 0.010 μm or more and 0.025 μm or less.