Resin-coated seamless can

Abstract

A resin-coated seamless can of the present invention is a resin-coated seamless can formed of a resin-coated metal sheet 1 which is produced by coating a polyester resin layer 3 containing polyethylene terephthalate onto a surface of a metal substrate 2, wherein the density of a polyester resin layer of a can inner surface side is set to equal to or more than 1.36 at a can barrel upper portion. Further, an infrared dichroic ratio (R1) of the polyester resin layer at the inner surface side of the can barrel portion which is expressed by a following formula (1) is set to equal to or more than 1.1. R1=Iw(⊥)/Iw(∥) . . . (1). In the formula (1), Iw(⊥) indicates an infrared absorption intensity of 973 cm −1 with respect to polarized infrared rays perpendicular to the can height direction at the can barrel portion, and Iw(∥) indicates an infrared absorption intensity of 973 cm −1 with respect to polarized infrared rays parallel to the can height direction at the can barrel portion.

What is claimed is:  
     
         1 . A resin-coated seamless can formed of a resin-coated metal sheet which is produced by coating a polyester resin layer containing polyethylene terephthalate on a surface of a metal substrate, 
 the improvement being characterized in that the density of the polyester resin layer at a can inner-surface side is equal to or more than 1.36 at an upper portion of a can barrel portion.    
     
     
         2 . A resin-coated seamless can according to  claim 1 , wherein the density of the polyester resin layer at the can inner surface side is equal to or less than 1.36 at a can bottom portion.  
     
     
         3 . A resin-coated seamless can formed of a resin-coated metal sheet which is produced by coating a polyester resin layer containing polyethylene terephthalate on a surface of a metal substrate, 
 the improvement being characterized in that an infrared dichroic ratio (R1) of the polyester resin layer at the inner surface side of the can barrel portion which is expressed by a following formula (1) is set to equal to or more than 1.1.      R 1= Iw (⊥)/ Iw (∥)  (1)    wherein, Iw(⊥): an infrared absorption intensity of 973 cm −1  with respect to polarized infrared rays perpendicular to the can height direction at the can barrel portion    Iw(∥): an infrared absorption intensity of 973 cm −1  with respect to polarized infrared rays parallel to the can height direction at the can barrel portion.    
     
     
         4 . A resin-coated seamless can according to  claim 3 , wherein an infrared dichroic ratio (R2) of the polyester resin layer at the inner surface side of the can bottom portion expressed by a following formula (2) is set to equal to or less than 1.1.  
         R 2= IB (⊥)/ IB (∥)  (2)  wherein, IB(⊥): an infrared absorption intensity of 973 cm −1  with respect to polarized infrared rays perpendicular to the metal substrate rolling direction at the can bottom portion,    IB(∥): an infrared absorption intensity of 973 cm −1  with respect to polarized infrared rays parallel to the metal substrate rolling direction at the can bottom portion.    
     
     
         5 . A resin-coated seamless can according to  claim 1  or  3 , wherein the resin-coated metal sheet is a sheet produced by forming the non-oriented polyester resin layer on the metal substrate.  
     
     
         6 . A resin-coated seamless can according to  claim 1  or  3 , wherein a thickness of the resin-coated seamless can is reduced by drawing/thinning drawing forming and/or ironing working forming such that a thickness of the can barrel portion becomes 20 to 85% of a thickness of the can bottom portion.  
     
     
         7 . A resin-coated seamless can according to  claim 1  or  3 , wherein the polyester resin layer is constituted of two layers in which a surface layer (A) is formed of polyethylene terephthalate/isophthalate containing equal to or less than 15 mol % of isophthalic acid and a lower layer (B) is formed of polyethylene terephthalate/isophthalate containing 8 to 25mol % of isophthalic acid.  
     
     
         8 . A resin-coated seamless can according to  claim 1  or  2 , wherein the intrinsic viscosity of the polyester resin which forms the polyester resin layer is equal to or more than 0.6 dl/g.  
     
     
         9 . A resin-coated seamless can according to  claim 1  or  3 , wherein the degree of crystallization due to the density method of the polyester resin layer at an upper portion of the can barrel portion falls in a range of 20 to 55%.