Surface treatment solution composition containing trivalent chromium and inorganic compound, and method for manufacturing hot dip galvanized steel sheet surface-treated using same

Patent metadata

Field	Value
Publication number	US-12221702-B2
Application number	US-201917288232-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Oct 24, 2018
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

Provided is a surface treatment solution composition comprising: 30 to 51 wt % of a trivalent chromium compound comprising chromium phosphate (A) and chromium nitrate (B) and having a content ratio of A/(A+B) that satisfies 0.3 to 0.6; 5 to 15 wt % of silane coupling agent; 0.2 to 3 wt % of vanadium-based anti-corrosive rust inhibitor; 3 to 12 wt % of colloidal silica; 0.5 to 5 wt % of polysiloxane copolymer; and 14 to 61.3 wt % of water, a hot dip galvanized steel sheet surface-treated using same, and a manufacturing method thereof. The hot dip galvanized steel sheet treated with the surface treatment solution composition containing trivalent chromium has an excellent corrosion resistance, blackening resistance, pipe-forming oil reactivity, and alkali resistance.

First claim

The invention claimed is:

1. A surface treatment solution composition comprising:
based on 100 wt % of a total solid content of the surface treatment solution composition,
37.7 to 58.1 wt % of a trivalent chromium compound comprising chromium phosphate and chromium nitrate, wherein a weight ratio of the chromium phosphate in a total weight of the chromium phosphate and the chromium nitrate is 0.89 to 0.95;
34.6 to 40.7 wt % of a silane coupling agent;
1.4 to 8.2 wt % of a vanadium-based anti-corrosive rust inhibitor;
4.2 to 6.6 wt % of colloidal silica; and
1.7 to 6.8 wt % of a polysiloxane copolymer.

2. The surface treatment solution composition of claim 1 , wherein the silane coupling agent is one or more selected from the group consisting of 2-(3,4 epoxycyclohexyl)-ethyltrimethoxysilane, 3-glycyloxypropyl trimethoxysilane, 3-glycyloxypropyl methyldiethoxysilane, 3-glycyloxypropyl triethoxysilane, N-2-(aminoethyl)-3-aminopropyl methyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyl trimethoxysilane, N-2-(aminoethyl)-3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-ureido propyltrimethoxysilane, and tetraethylorthosilicate.

3. The surface treatment solution composition of claim 1 , wherein the vanadium-based anti-corrosive rust inhibitor is one or more selected from the group consisting of vanadium pentoxide (V 2 O 5 ), metavanadic acid (HVO 3 ), ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride (VOCl 3 ), vanadium trioxide (V 2 O 3 ), vanadium dioxide (VO 2 ), vanadium oxysulfate (VOSO 4 ), vanadium oxyoxalate [VO(COO) 2 ], vanadium oxyacetylacetonate [VO(OC(CH 3 )=CHCOCH 3 )) 2 ], vanadium acetylacetonate [V(OC(CH 3 ))=CHCOCH 3 )) 3 ], vanadium trichloride (VCl 3 ), vanadium sulfate (VSO 4 ·8H 2 O), vanadium dichloride (VCl 2 ), and vanadium oxide (VO).

4. The surface treatment solution composition of claim 1 , wherein the colloidal silica includes silica particles dispersed in an acidic aqueous solution having a pH of 3 to 5, and the silica particles have a particle size of 5 to 15 nm.

5. The surface treatment solution composition of claim 1 , wherein the polysiloxane copolymer has a weight average molecular weight of 300 to 1500.

6. A method for manufacturing a surface-treated hot dip galvanized steel sheet, comprising:
coating the surface treatment solution composition of claim 1 on a hot dip galvanized steel sheet on which a hot dip galvanized layer is formed; and
drying the coated surface treatment solution composition to form a trivalent chromate coating layer.

7. The method of claim 6 , wherein in the coating of the surface treatment solution composition, the surface treatment solution composition is coated at a thickness of 2.14 to 3.57 μm.

8. The method of claim 6 , wherein the drying of the coated surface treatment solution composition is performed at a temperature of 40 to 60° C. according to a peak metal temperature (PMT) of the steel sheet.

9. The method of claim 6 , wherein the drying of the coated surface treatment solution composition is performed in a hot air drying furnace or an induction heating furnace.

10. The method of claim 9 , wherein an internal temperature of the hot air drying furnace is 100 to 200° C.

11. The method of claim 9 , wherein a current applied to the induction heating furnace is 1000 to 3500 A.

12. The method of claim 6 , further comprising air-cooling the trivalent chromate coating layer.

13. The method of claim 6 , wherein the method for manufacturing a hot dip galvanized steel sheet includes a continuous process, and a speed of the continuous process is 80 to 100 mpm.

14. A surface-treated hot dip galvanized steel sheet comprising:
a steel sheet;
a hot dip galvanized layer formed on at least one surface of the steel sheet; and
a trivalent chromate coating layer formed on the hot dip galvanized layer,
wherein the trivalent chromate coating layer comprises:
37.7 to 58.1 wt % of a trivalent chromium compound comprising chromium phosphate and chromium nitrate, wherein a weight ratio of the chromium phosphate in a total weight of the chromium phosphate and the chromium nitrate is 0.89 to 0.95;
34.6 to 40.7 wt % of a silane coupling agent;
1.4 to 8.2 wt % of a vanadium-based anti-corrosive rust inhibitor;
4.2 to 6.6 wt % of colloidal silica; and
1.7 to 6.8 wt % of a polysiloxane copolymer.

15. The surface-treated hot dip galvanized steel sheet of claim 14 , wherein the trivalent chromate coating layer has a thickness of 0.3 to 0.5 μm.

Assignees

• Posco
• Posco Co Ltd

Inventors

• Cho Soo-Hyoun
• Lee Kang-Min

Classifications

• Y10T428/265

  1 mil or less · CPC title

• Y10T428/12799

  Next to Fe-base component [e.g., galvanized] · CPC title

• Y10T428/12757

  Fe · CPC title

• Y10T428/12569

  Synthetic resin · CPC title

• Y10T428/263

  Coating layer not in excess of 5 mils thick or equivalent · CPC title