Seamless Can Ink Layer Thickness Control
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Solution Overview
Problem
Conventional seamless can manufacturing results in uneven ink layer thickness, leading to aesthetic issues, wrinkling, and reduced coated-film strength due to the level difference in the overlapping portion during neck-in processing.
Innovation Solution
A seamless can design where the ink layer area ratio at the overlapping portion is controlled by adjusting the ink area ratio of halftone dots, with a gradual decrease at the front-end and increase at the rear-end, matching the layer thickness of non-overlapping portions, using a curved surface printing method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional curved surface printing is used to print on the can body, then the printing process can be completed, but the ink layer thickness becomes uneven in the overlapping portion, causing level differences
Solution Approach 1:
The patent applies different ink area ratios to different portions of the printing plate. Specifically, the front-end portion and rear-end portion (which form the overlapping portion) use a smaller ink area ratio compared to the intermediate portion. This local differentiation of printing parameters ensures that the overlapping portion receives less ink, compensating for the double-layer accumulation and achieving uniform overall ink layer thickness.
2Quantity of substance
If the ink layer in the overlapping portion is thicker, then the printing coverage is improved, but wrinkles are developed during neck-in processing and aesthetic appearance is degraded
Solution Approach 1:
The patent implements local quality control by adjusting the ink area ratio in the front-end and rear-end portions of the printing plate to be smaller than in the intermediate portion. This creates a non-uniform ink distribution pattern that compensates for the overlapping effect, ensuring that the final ink layer thickness remains uniform across the entire can body, including the overlapping portion, thereby preventing wrinkles and maintaining aesthetic appearance.
3Ease of manufacture
If varnish is applied on the thick ink layer in the overlapping portion, then the coating is completed, but the coated-film strength is degraded and the surface becomes susceptible to scratches
Solution Approach 1:
The patent performs preliminary action by adjusting the ink area ratio before the varnishing process. By pre-controlling the ink layer thickness in the overlapping portion through modified printing parameters, the substrate prepared for varnishing has uniform thickness, which provides a consistent foundation for the varnish coating, ensuring uniform coating quality and strength across the entire surface.
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 approach reduces the level difference, prevents wrinkling, and enhances the aesthetic appearance by maintaining consistent ink layer thickness, thereby improving the coated-film strength and reducing the occurrence of neck wrinkling.
Implementation Method 1
an ink area ratio for at least one of the ink layer at a front-end portion and an ink layer at a rear-end portion is smaller than an ink area ratio for an ink layer in a portion in continuity with the overlapping portion
Data Source
AI summary
A seamless can in which an ink layer is transferred onto a can body thereof by a curved surface printing is provided. The ink layer which has been transferred has an overlapping portion which is formed by mutually overlapping a front-end portion of the ink layer and a rear-end portion of the ink layer in a circumferential direction of the can body. An ink area ratio for at least one of the front-end portion and the rear-end portion is smaller than an ink area ratio of an intermediate portion of the ink layer which is adjacent to and continuous with the overlapping portion and excludes the overlapping portion.