# US 4,392,582 A · Retortable bonded can

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- Number: US 4,392,582 A
- Document ID: US4392582A
- Status: Granted
- Kind: A
- Application number: 06/251,945
- Filed: 1981-04-07
- Granted: 1983-07-12
- Earliest claimed: 1980-05-26
- Assignees: Toyo Seikan Kaisha, Ltd.
- Inventors: Yoichi Kitamura; Hisashi Hotta
- Web page: https://patentgrep.com/patent/US4392582A

## CPC

- C25D 11/38: Chromatising
- C08G 8/04: of aldehydes
- C09D 163/00: Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
- Y10S 220/917: Corrosion resistant container
- Y10T 428/12549: Adjacent to each other
- Y10T 428/12569: Synthetic resin
- Y10T 428/1259: Oxide
- Y10T 428/1359: Three or more layers [continuous layer]
- Y10T 428/31529: Next to metal
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A retortable bonded TFS can coated with an organic lacquer film in which the seaming portion of the can body is bonded with an organic adhesive, characterized in that (1) the amounts of the metallic chromium layer and the chromium oxide layer deposited are 70-130 mg/m.sup.2 and 5-30 mg/m.sup.2, respectively, as metallic chromium; the amount of alkali-soluble chromium in these layers after heating at 210.degree. C. for 10 minutes is not more than 12 mg/m.sup.2 and not more than 70% by weight of the amount of the deposited chromium oxide before heating; the area of thickness unevenness of the chromium oxide is not more than 10%; and the amount of metal exposed is not more than 30 mg/dm.sup.2, expressed as the amount of copper deposited (2) the organic lacquer film layer is a baked and cured film of a mixed lacquer composed of 70 to 85 parts by weight of an epichlorohydrin-bisphenol A type epoxy resin having a number average molecular weight of 2900 to 3750 and 30 to 15 parts by weight of a resol-type phenolic resin derived from a monohydric phenol, bisphenol A and an aldehyde; the phenolic resin has such a molecular weight distribution that the proportion of a high-molecular-weight portion having 3 or more rings is 60 to 70% by weight and the proportion of a low-molecular-weight portion having 2 or less rings is 40 to 30% by weight; and the baked and cured film contains 83 to 87 parts by weight of the epoxy resin and 17 to 13 parts by weight of the phenolic resin, and (3) the adhesive is a linear polyamide adhesive.

## Claims

### Claim 1

A retortable bonded can made of an electrolytic chromic acid treated steel sheet wherein at least a part of the can body is composed of a steel sheet having on at least one surface thereof a metallic chromium layer, a chromium oxide layer and an organic lacquer film layer arranged in this order from the steel sheet surface and at least a part of the seaming portion of the can body is bonded with an organic adhesive, characterized in that
(1) the amounts of the metallic chromium layer and the chromium oxide layer deposited are 70-130 mg/m.sup.2 and 5-30 mg/m.sup.2, respectively, as metallic chromium; the amount of alkali-soluble chromium in these layers after heating at 210.degree. C. for 10 minutes is not more than 12 mg/m.sup.2 and not more than 70% by weight of the amount of the deposited chromium oxide before heating; the area of thickness unevenness of the chromium oxide is not more than 10%; and the amount of metal exposed, expressed as the amount of copper deposited, is not more than 30 mg/dm.sup.2,
(2) the organic lacquer film layer is a baked and cured film of a mixed lacquer composed of 70 to 85 parts by weight of an epoxy resin having a number average molecular weight of 2900 to 3750 and derived from epichlorohydrin and bisphenol A and 30 to 15 parts by weight of a resol-type phenolic resin, the total amount of these resins being 100 parts by weight; the phenolic resin is obtained by reacting a mixed phenol composed of 5 to 20% by weight of a monohydric phenol and 95 to 80% by weight of bisphenol A with an aldehyde in the presence of ammonia and has such a molecular weight distribution that the proportion of a high-molecular-weight portion having 3 or more rings is 60 to 70% by weight and the proportion of a low-molecular-weight portion having 2 or less rings is 40 to 30% by weight; and the baked and cured film contains 83 to 87 parts by weight of the epoxy resin and 17 to 13 parts by weight of the phenolic resin based on 100 parts by weight of the epoxy resin and the phenolic resin combined, and
(3) the adhesive is a linear polyamide adhesive.