A laminated steel sheet for a two-piece can body with a high strain level satisfying the following formulae, the polyester resin layer composing the laminated steel sheet having a center line surface roughness (Ra) of 0.2 μm to 1.8 μm: r1≤r,0.1≤r1/R≤0.25, and 1.5≤h/(R−r)≤4wherein h is the height of
A laminated steel sheet for a two-piece can body with a high strain level satisfying the following formulae, the polyester resin layer composing the laminated steel sheet having a center line surface roughness (Ra) of 0.2 μm to 1.8 μm: r1≤r,0.1≤r1/R≤0.25, and 1.5≤h/(R−r)≤4wherein h is the height of the two-piece can body, r is the maximum radius, r1 is the minimum radius, and R is the radius of the circular laminated steel sheet before forming having the same weight as the can body.
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1. A method for producing a two-piece can body, comprising: (i) providing a circular laminated steel sheet satisfying the following formulae: r1≤r, 0.1≤r1/R≤0.25, and1.5≤h/(R−r)≤4wherein h is the height, r is the maximum radius and r1 is the minimum radius of the two-piece can body, and R is the rad
1. A method for producing a two-piece can body, comprising: (i) providing a circular laminated steel sheet satisfying the following formulae: r1≤r, 0.1≤r1/R≤0.25, and1.5≤h/(R−r)≤4wherein h is the height, r is the maximum radius and r1 is the minimum radius of the two-piece can body, and R is the radius of the circular laminated steel sheet,the laminated steel sheet comprising a polyester resin layer on at least one side of the steel sheet, the surface of the polyester resin layer having a center line surface roughness Ra of 0.2 μm to 1.8 μm; and(ii) forming the can body by drawing the laminated steel sheet into a tube having a predetermined radius r of the can body, the can body having a top opening and a closed bottom,wherein the formed can body satisfies the following formulae: r1≤r, 0.1≤r1/R≤0.25, and1.5≤h/(R−r)≤4;wherein the can body is subjected to heat treatment during the forming step so as to satisfy the following formulae: r1≤r, 0.2≤r1/R≤0.5, and1.5≤h/(R−r)≤2.5. 2. The method according to claim 1, wherein step (ii) comprises one-step drawing the laminated steel sheet. 3. The method according to claim 1, wherein step (ii) comprises multi-step drawing the laminated steel sheet. 4. The method according to claim 1, wherein step (ii) comprises drawn and ironed (DI) processing. 5. The method according to claim 1, further comprising (iii) inward doming the bottom of the formed can body. 6. The method according to claim 1, further comprising (iv) trimming the top opening of the formed can body. 7. The method according to claim 1, wherein an amount of steel trimmed from the formed body in step (iv) is 20% or less of R. 8. The method according to claim 1, further comprising (v) subjecting the top opening of the formed can body to diametrical reduction, thereby reducing the radius of the opening to a predetermined radius r1 of the can body. 9. The method according to claim 8, wherein step (v) comprises one-step diametrical reduction of the top opening. 10. The method according to claim 8, wherein step (v) comprises multi-step diametrical reduction of the top opening. 11. The method according to claim 1, wherein the steel sheet is tin-free steel sheet comprising a metal chromium layer in a coating weight of 50 to 200 mg/m2 and a chromium oxide layer in a coating weight of 3 to 30 mg/m2, in terms of metal chromium. 12. The method according to claim 1, wherein the steel sheet is tinplate comprising a tin coating of 0.5 to 15 g/m2. 13. The method according to claim 1, wherein the provided steel sheet has a thickness of 0.15 to 0.30 mm. 14. The method according to claim 1, wherein the surface of the polyester resin layer has a center line surface roughness Ra of 0.4 μm to 1.0 μm. 15. The method according to claim 1, wherein the surface of the polyester resin layer has 60 degree glossiness of 30 to 100. 16. The method according to claim 1, wherein the polyester resin comprises polyethylene terephthalate copolymerized with isophthalic acid. 17. The method according to claim 1, wherein the polyester resin layer has a plane orientation factor of 0.04 or less, and a crystallization temperature of 140° C. to 160° C. 18. The method according to claim 1, wherein the polyester resin layer has a thickness of 5 μm to 50 μm. 19. The method according to claim 1, wherein the heat treatment is carried out at a temperature of 150° C. to 220° C. 20. The method according to claim 19, wherein the can body is heated to a temperature of 170° C. or higher and not higher than the melting temperature of the polyester resin. 21. The method according to claim 1, wherein providing the laminated steel sheet comprises bonding a polyester resin film to the steel sheet by heat lamination under pressure using a lamination roll having a predetermined center line surface roughness (Ra) of 0.2 μm to 1.8 μm. 22. The method according to claim 1, wherein providing the laminated steel sheet comprises extruding a molten polyester resin through a T die so as to coat the heated steel sheet on the run, and subsequently cooling the coated steel sheet by passing between cooling rolls, and using a lamination roll having a predetermined center line surface roughness (Ra) of 0.2 μm to 1.8 μm.
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