UV-Curable Lacquer Masking for Press Plate Structuring
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Solution Overview
Problem
Existing methods for structuring press plates and endless strips, such as screen printing and photo processes, face challenges in reproducibility and resolution, especially when creating complex three-dimensional structures, due to the need for accurate mask positioning and the limitations of wax-based masking techniques which result in incomplete wetting and high cleaning complexity.
Innovation Solution
The use of a UV-hardening lacquer applied directly to the press plates or endless strips, which is partially hardened using UV light, allowing for precise adherence and enabling deeper etching with improved surface structure resolution, combining the advantages of wax technology and screen printing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photosensitive layer and mask are used for structuring the surface, then the surface can be etched to create structured patterns, but the reproducibility and image accuracy deteriorate due to positioning errors of the mask relative to the press plate
Solution Approach 1:
The patent uses a printing head to directly print the mask pattern onto the press plate surface, eliminating the need for separate physical masks and their positioning. The digital mask data is copied directly onto the workpiece through the printing head, ensuring perfect positional accuracy without mechanical alignment errors.
Solution Approach 2:
The patent extracts the mask pattern from a separate physical medium and integrates it directly into the printing process. The mask is no longer a separate component that needs positioning, but is instead generated and applied in-situ by the printing head, removing the source of positioning errors.
2Ease of manufacture
If wax is applied as a mask directly to the press plate, then the mask application process is simplified, but the resolution and structural detail deteriorate because the wax hardens too quickly and forms incompletely wetted structures
Solution Approach 1:
The patent changes the material parameters from wax to UV-curable lacquer, which allows for better control of the application process. The lacquer remains in a workable state until UV irradiation triggers rapid hardening, enabling complete wetting and high resolution before the material sets, thus resolving the contradiction between ease of application and resolution.
Solution Approach 2:
The patent employs a two-stage process: first applying the lacquer in a liquid state that can flow and wet the surface completely, then applying UV irradiation to trigger hardening. This periodic action (apply then cure) allows the material to achieve both complete coverage and high resolution before setting.
3Shape
If multiple masks are applied sequentially to create three-dimensional structures, then complex surface features can be achieved, but the production complexity and cost increase due to the need for accurate positioning of each mask
Solution Approach 1:
The patent uses a printing head that can directly print multiple mask layers onto the press plate in sequence, with each layer being digitally positioned according to the desired 3D structure. This eliminates the need for physical mask alignment and reduces production complexity while maintaining the ability to create complex three-dimensional features.
4Ease of manufacture
If wax is used as a mask, then the mask can be applied directly without intermediate processes, but the cleaning process becomes extremely complex and time-consuming because the wax cannot be removed with chemical treatment
Solution Approach 1:
The patent changes the mask material from wax to UV-curable lacquer, which has the property of being removable by chemical treatment after the etching process. The lacquer can be dissolved or degraded chemically, allowing for simple and quick cleaning of the press plate surface without requiring complex mechanical removal processes.
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 enhances reproducibility and resolution, allowing for the production of accurately structured surfaces with three-dimensional features, similar to natural surfaces, while simplifying the cleaning process and reducing the complexity of mask application, enabling precise matching of impregnated paper surfaces.
Implementation Method 1
whereby the applied lacquer is at least partially hardened by irradiation with UV light
Data Source
AI summary
A device for structuring the surface of a metal pressed sheet or of an endless strip, comprising a support device adapted to support the metal pressed sheet or endless strip during structuring, and a spray head and a slideway adapted to permit movement of the spray head into a desired position within a plane defined by an X and a Y coordinate. The spray head is further adapted to move in a Z direction with reference to a work surface which is spanned by the X and Y direction, and the spray head is guided by means of a digitalized template that is identical to the printed image of an impregnated paper used in a further pressing process. Independent drive elements are connected to a control unit and configured to move the spray head into the desired position.