Seamless Can Resin Coating for Full-Surface Color and Adhesion
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Solution Overview
Problem
Existing resin-coated seamless cans lack decorative properties due to limited printing and painting on the bottom section, leading to poor aesthetic appeal and increased production complexity, and the inclusion of pigments in resin coatings complicates processability and adhesion.
Innovation Solution
A seamless can with a thermoplastic resin coating on a polyester-based paint film containing a colorant and curing agent, applied to the outer surface, ensures the entire can, including the bottom section, is colored without additional printing or painting processes, maintaining processability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If printing is applied only to the body section of the can, then the printing process is simple and productive, but the decorative properties of the entire can are poor
Solution Approach 1:
The patent applies preliminary action by incorporating colorants into the resin coating material before the can forming process. The entire can surface, including the bottom section, is pre-colored through the resin coating applied to the metal sheet before drawing and ironing, eliminating the need for post-forming printing operations on the bottom section.
Solution Approach 2:
The patent changes the parameter of color application from post-forming printing to pre-forming resin coating with colorants. By incorporating colorants into the resin coating material and applying it before can forming, the entire surface including bottom sections achieves uniform coloring without additional printing processes.
2Ease of manufacture
If painting is applied to the chime portion and bottom portion separately, then the entire can is colored, but the number of processes increases and productivity decreases
Solution Approach 1:
The patent merges multiple coloring operations into a single resin coating process. By applying the resin coating with colorants to the metal sheet before can forming, the entire can surface including body section, chime portion, and bottom portion is colored in one operation, eliminating separate painting steps for different sections.
Solution Approach 2:
The resin coating serves multiple functions simultaneously: it provides corrosion resistance, adhesion, and universal coloring for the entire can surface including areas that would traditionally require separate painting operations. The coating system is designed to withstand severe processing while maintaining its protective and decorative functions.
3Ease of manufacture
If a colorant is added to the resin coating, then the entire can can be colored, but the processability and adhesion of the resin coating become difficult to maintain
Solution Approach 1:
The patent uses composite materials by incorporating colorants into the resin coating formulation. The resin coating comprises a base resin and colorants that are compatible with the resin matrix, creating a composite material that maintains adhesion and processability while providing coloring capability for the entire can surface.
Data Source
AI summary
A seamless can having a bottom section and a body section, wherein a thermoplastic resin coating is formed on an outer surface side of the can over a polyester-based paint film. The polyester-based paint film includes a polyester-based paint composition which contains a colorant in an amount of 20 parts by mass or less relative to 100 parts by mass of a total resin solid content and a curing agent in an amount of 5 to 43 parts by mass relative to 100 parts by mass of a polyester resin, and an entire outer surface of the can including the bottom section is colored. Also disclosed is a resin-coated metal sheet for forming a seamless can including the thermoplastic resin coating that is applied over a polyester-based paint film on a surface of the metal sheet, the polyester-based paint film having a thickness of 7 μm or less.