Microporous Polyolefin Sheet Casting Air Biting Pressure Control
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Solution Overview
Problem
As film forming speed increases, air biting pressure between the sheet and the casting cooling device rises, leading to decreased adhesion, thickness variation, and contamination of the casting cooling device surface due to trapped air and volatile components, which complicates stable sheet formation and long-term operation.
Innovation Solution
A production device for microporous polyolefin resin sheets incorporating a decompression chamber with a sealing member and partition plate to aspirate air and control airflow, combined with a rectifier to block gaps and stabilize sheet adhesion, and a receiving plate to manage liquid droplets, ensuring stable sheet formation even at higher speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If film forming speed is increased to accommodate increasing demand for resin sheets, then productivity is improved, but air biting pressure between the sheet and casting cooling device becomes high, causing adhesion to decrease and air to be trapped between the sheet and casting cooling device
Solution Approach 1:
The patent extracts and removes the harmful air from between the sheet and casting cooling device by introducing a decompression chamber with vacuum suction. This allows the sheet to maintain good adhesion to the casting cooling device even at high film forming speeds by continuously removing air that would otherwise cause air biting defects and thickness variation.
Solution Approach 2:
The decompression chamber acts as an intermediary device between the sheet and casting cooling device. It mediates the interaction by creating a controlled vacuum environment that facilitates proper adhesion while allowing high-speed operation, thus resolving the contradiction between speed and adhesion quality.
2Productivity
If film forming speed is increased, then productivity is improved, but thickness variation and physical property variation occur due to trapped air
Solution Approach 1:
The decompression chamber extracts air from the region between the sheet and casting cooling device, preventing air entrapment that would cause thickness variation. This ensures uniform sheet thickness even at high production speeds.
3Reliability
If air is aspirated with a decompression chamber to remove air between sheet and cooling device, then adhesion is improved, but turbulence in air flow such as air vortex or air retention arises near the sheet
Solution Approach 1:
The patent applies local quality by positioning the vacuum suction ports at specific locations within the decompression chamber and using partition plates to create localized vacuum zones. This ensures effective air removal at the sheet-casting interface while maintaining stable, laminar air flow patterns throughout the chamber, preventing turbulence and air vortex formation.
4Stability of the object's composition
If a rectifier is provided to regulate air flow in the decompression chamber, then air vortex is prevented, but device complexity increases
Solution Approach 1:
The decompression chamber is segmented into multiple zones using partition plates, with vacuum suction ports strategically positioned in each zone. This segmentation approach stabilizes air flow and prevents vortex formation while keeping the overall structure relatively simple and modular.
5Quantity of substance
If the upper plate of the decompression chamber is made non-heating to receive and condense aspirated air, then volatile components can be condensed, but when liquid accumulates it drops down and contaminates the casting cooling device surface
Solution Approach 1:
The patent extracts and removes the condensed liquid from the decompression chamber using a receiving plate with drainage holes positioned below the vacuum suction ports. This prevents liquid accumulation and subsequent contamination of the casting cooling device surface, while still allowing effective condensation of volatile components in the upper chamber region.
Solution Approach 2:
The receiving plate acts as an intermediary device between the condensation zone and the casting cooling device. It captures and drains condensed liquid, preventing direct contact with the casting cooling device surface, thus resolving the contradiction between condensation efficiency and contamination prevention.
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 solution effectively stabilizes sheet formation by reducing air biting pressure, minimizing thickness and physical property variations, and preventing contamination of the casting cooling device surface, allowing for continuous and high-quality sheet production at increased speeds.
Implementation Method 1
a decompression chamber that is installed upstream from the mouthpiece in a conveying direction of the casting cooling device and aspirates air between the sheet discharged from the mouthpiece and the casting cooling device
Implementation Method 2
a sealing member provided in at least a peripheral portion of a surface opposing the casting cooling device and in physical contact with the casting cooling device
Implementation Method 3
a partition plate provided across a sheet width direction in a vicinity of an opening part opposing the mouthpiece
Implementation Method 4
a casting cooling device that cools and solidifies a sheet discharged from the mouthpiece while conveying the sheet
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present invention provides a production method for a microporous polyolefin resin sheet which enables the stable formation of a sheet having uniform crystallinity, even when the speed of the casting cooling device is high, and has excellent thickness uniformity and appearance grade. The production device for a microporous polyolefin resin sheet according to the present invention includes a mouthpiece that extrudes a molten resin in a sheet shape; a casting cooling device that cools and solidifies a sheet extruded from the mouthpiece while conveying the sheet; and a decompression chamber that is installed upstream from the mouthpiece in a conveying direction of the casting cooling device and aspirates air between the sheet extruded from the mouthpiece and the casting cooling device; and further includes a rectifier that is installed and blocks a gap between the sheet discharged from the mouthpiece and the cast surface. The decompression chamber of the production device for a microporous polyolefin resin sheet according to the present invention includes: a sealing member provided in at least a peripheral portion of a surface opposing the casting cooling device and in physical contact with the casting cooling device; and a partition plate provided across a sheet width direction in a vicinity of an opening part opposing the mouthpiece.