Copolymer coated steel strip

An object of the present invention is to provide a multiple coated composite steel strip having a superior resistance to corrosion, an excellent weldability, and a very high workability.

The above-mentioned object can be attained by the multiple coated composite steel strip of the present invention, which comprises

(A) a substrate consisting of a steel strip; and

(B) at least one composite coating layer formed on at least one surface of the steel strip substrate, and comprising;

(a) a first coating layer formed on the surface of the steel strip substrate and comprising a plated metallic material,

(b) a second coating layer formed on the first coating layer and comprising an electrolytically deposited chromate material having a total content of chromium of 40 to 120 mg/m² and a content of Cr₂ O₃ of 45% by weight or more; and

(c) a third coating layer formed to a thickness of 0.5 to 3.0 μm on the second coating layer and comprising a polymeric matrix consisting essentially of at least one polymer selected from the group consisting of acrylic acid homopolymers and copolymers, acrylic acid ester homopolymers and copolymers, methacrylic acid homopolymers and copolymers, and methacrylic acid ester homopolymers and copolymers, and 15% to 40% based on the weight of the polymeric matrix, of colloidal silica particle having a size of 1 to 12 m μm.

Preferably, the acrylic acid copolymer is selected from a copolymer of 70 to 95 molar % of at least one type of olefin having 2 to 6 carbon atoms with the balance consisting of acrylic acid.

Dimension and Technical Property:
1) Tensile strength: 300 to 420MPa
2) Elongation: Min. 15%
3) Thickness steel foil: 0.15 mm
4) Copolymer: 0.058mm for each side
5) Width: 15 to 600mm
6) Tape length: 1, 000m ~6.000m
7) Core material: Iron or plastic
8) Temper: T1 to T5
9) ID (inner diameter): 150mm

Packing: Wooden pallets, wooden packaging suits sea transportation
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