Coin Surface Porous Layer Ink Adhesion
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Solution Overview
Problem
Existing methods for printing images on metal coins fail to achieve adequate adhesion, making the printed coins unsuitable for public circulation due to lack of durability.
Innovation Solution
A method involving the formation of macropores and micropores on the metal surface, followed by the application of solvent-based inks using inkjet printers and a transparent top coat, ensuring strong adhesion and durability of the printed image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional printing methods (silk screen, inkjet on smooth surface) are used to print images on metal coins, then the printing process can be completed, but the adhesion of the image to the coin surface is inadequate, making the coins unsuitable for public circulation
Solution Approach 1:
The invention creates a porous layer on the metal coin surface by depositing a material (such as nickel or copper) and then etching it to form macropores and micropores. This porous structure dramatically increases the surface area and provides mechanical interlocking for the ink, enabling the printed image to adhere firmly to the coin surface and withstand circulation.
Solution Approach 2:
The invention performs preliminary surface preparation by forming the porous layer before applying the ink. The macropores and micropores are created in advance to provide anchoring points for the ink particles, ensuring that when the ink is applied, it immediately bonds to the prepared surface structure, achieving strong adhesion from the outset.
2Reliability
If a porous layer with macropores and micropores is formed on the metal surface before printing, then the adhesion and durability of the printed image are significantly improved, but the manufacturing process becomes more complex
Solution Approach 1:
The invention combines multiple functions into a single integrated layer: the deposited metal or copper layer serves both as a protective coating and as the substrate for the porous structure. The porous layer is formed by depositing one material and etching it, creating both macropores for ink retention and micropores for mechanical bonding, thus achieving multiple objectives in one process sequence.
Solution Approach 2:
The invention controls the etching parameters to create a specific porous structure with defined macropore and micropore characteristics. By adjusting etching time, chemical composition, and deposition thickness, the process optimizes the pore structure for maximum ink adhesion while maintaining a manageable manufacturing complexity.
3Reliability
If multiple etching stages are used to create macropores and micropores, then the ink adhesion is enhanced, but the production time and cost increase
Solution Approach 1:
The invention segments the porous structure into two distinct components: macropores (larger pores) for ink retention and micropores (smaller pores) for mechanical bonding. This segmentation allows each pore type to perform its specific function efficiently, achieving superior adhesion while potentially using a single etching step rather than multiple sequential etching processes.
Solution Approach 2:
The deposited metal or copper layer acts as an intermediary material between the coin substrate and the ink. This intermediate layer is specifically engineered with a porous structure that provides both macropores and micropores, serving as a bonding interface that enhances ink adhesion without requiring direct ink-to-coin-substrate bonding, thus simplifying the overall process.
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 method provides a durable and adhesive image on metal coins, making them suitable for public circulation by enhancing the adhesion of the printed image to the metal surface.
Implementation Method 1
a porous layer is formed on the metal surface... a solvent-based ink is applied to the porous layer... the ink is absorbed into the pores
Implementation Method 2
the ink is air dried
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method of printing on a metal surface includes steps of forming a plurality of macropores (110) on at least a portion of a metal surface. A plurality of micropores (112) are formed within and adjacent to the macropores. The metal surface is cleaned, and a first ink having a first color is applied to the macropores and micropores to form at least one image (114) on the metal surface. Preferably, the ink is applied using an inkjet printer. The ink is dried. A second ink (120) having a second color may also be applied to the metal surface and then dried. Additional inks may also be applied. A lacquer top coat (122) may be applied to the metal surface on top of the first ink (and additional inks, if provided). Preferably, the metal surface is part of a coin (100).