Wide Casting Belt Joint Mark Removal for Film Manufacturing
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Solution Overview
Problem
The existing methods for manufacturing wide cellulose acylate films using a wide casting belt face challenges in eliminating marks caused by belt welding, limiting the maximum width of the film to 1800 mm or less due to central joint issues, which hampers the production of larger polarizer and optical compensation films.
Innovation Solution
A method involving a wide casting belt with integral left and right belts, where the central belt is welded to form a continuous support, and the film is processed through casting, stretching, trimming, and drying operations to remove the mark parts caused by the joints, allowing for the production of films wider than 1500 mm without visible welding marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a wide casting belt is used to increase film width, then the film width can be increased beyond 2030 mm, but welding joints must be formed on the belt which create visible marks on the film
Solution Approach 1:
The harmful welding joint marks are extracted and removed from the belt surface through abrasion processing before film casting. The joints are ground and polished to eliminate visible marks, ensuring the film surface quality is not compromised by the presence of joints.
Solution Approach 2:
The belt joints are prepared in advance by performing welding and subsequent abrasion processing before the film casting operation. This preliminary preparation ensures that when the film is cast on the belt, the joint areas are already processed and will not create visible marks on the final film product.
2Object-generated harmful factors
If the belt width is limited to 2030 mm to avoid welding joints, then film quality is maintained, but the maximum film width is restricted to 1800 mm or less
Solution Approach 1:
The wide belt is divided into multiple sections that are joined together through welding. By segmenting the belt into manageable parts that can be welded and then processed, the system achieves widths beyond 2030 mm while maintaining the ability to process joints to eliminate marks.
Solution Approach 2:
The surface properties of the belt at joint areas are changed through abrasion processing. The joint areas undergo mechanical treatment to alter their surface roughness and appearance, transforming them from mark-causing features to imperceptible areas on the final film.
3Length of stationary object
If multiple belts are welded together to increase width, then film width can exceed 2030 mm, but the number of welding joints increases creating more marks
Solution Approach 1:
Multiple belt sections are merged into a single continuous wide belt through welding. The joints between sections are then processed to unify their appearance with the rest of the belt surface, effectively combining multiple segments into a visually homogeneous structure.
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
This method enables the manufacturing of wide films without central joint marks, maintaining film quality and allowing for increased width production while controlling intrafacial retardation and film thickness, thus addressing the limitations of current techniques.
Implementation Method 1
a dope is casted on a belt, a some of solvent is dried and stripped off (detached)
Implementation Method 2
the welded part should be clearly abraded even without encountering problems during film formation
Data Source
AI summary
A method for manufacturing a wide film comprises a casting operation, a stretching operation, and a trimming operation. The casting operation is a process of casting a film using a wide casting belt including a central belt, a left belt having a right end formed integrally with a left end of the central belt through a left joint in a length direction of the central belt, and a right belt having a left end formed integrally with a right end of the central belt through a right joint in the length direction of the central belt. The stretching operation is a process of stretching a film stripped off from the wide casting belt using a tenter. The trimming operation is a process of trimming predetermined parts of left and right sides of the stretched film. In the trimming operation, mark parts by the left and right joints are also trimmed.