Seamless tanks and coated metal sheets

By using a specific ratio of polyester resin and curing agent in the coating film on the inner surface of the coated metal sheet, and controlling the gel fraction and aromatic dicarboxylic acid content, the problems of metal exposure, coating peeling and insufficient fragrance adsorption resistance of the coated metal sheet during deep drawing and thinning are solved, thus realizing the production of high-performance seamless cans.

CN117794823BActive Publication Date: 2026-05-26TOYO SEIKAN GRP HLDG LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
TOYO SEIKAN GRP HLDG LTD
Filing Date
2022-08-01
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Existing coated metal sheets are prone to problems such as metal exposure, coating peeling, reduced corrosion resistance, and insufficient fragrance adsorption during deep drawing and thinning processes, especially after heat treatment and prolonged storage.

Method used

Using a specific ratio of polyester resin and curing agent in the coating of the inner surface of the coated metal sheet, controlling the gel fraction and aromatic dicarboxylic acid components, ensures that the crosslinking degree of the coating is moderate, inhibits enthalpy relaxation and coating embrittlement, improves the adhesion and corrosion resistance of the coating to the metal substrate, and reduces aroma adsorption.

Benefits of technology

It effectively prevents coating defects, improves coating coverage and corrosion resistance, reduces the risk of coating peeling, enhances fragrance adsorption resistance, and ensures the excellent performance of seamless cans after harsh processing and heat treatment.

✦ Generated by Eureka AI based on patent content.

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Patent Text Reader

Abstract

This invention relates to a seamless can having an inner surface coating with excellent coating coverage and corrosion resistance, at least on the inner surface side, and a coated metal sheet capable of being formed into such a seamless can. The inner surface coating is characterized by containing a polyester resin, wherein when the total amount of polycarboxylic acid components in the polyester resin is set to 100 mol%, the content of aromatic dicarboxylic acids is 70 mol% or more, and the gel fraction (A) of the inner surface coating, as shown by the following formula, is less than 90%. Gel fraction (A) = (W2a / W1a) × 100 (%)…(1a) where W1a represents the mass of the inner surface coating after separation from the coated metal substrate cut from the seamless can, and W2a represents the mass of the separated inner surface coating after immersion in MEK at room temperature for 60 minutes, followed by removal and drying.
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