Aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance, and manufacturing method and surface treating agent therefor

Abstract

Disclosed is an aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance, and an environmental-friendly surface treating agent therefor, wherein after the surface treatment of the aluminium-zinc hot-plated steel plate using an environmental-friendly surface treating agent consisting of the components of a matrix resin compounded from a particular solvent-free aqueous aliphatic polyurethane dispersion and aqueous polyurethane-acrylic acid copolymer, an organic silicon compound, a matrix resin curing agent, a water-soluble metal salt compound and a high-density polyethylene lubrication auxiliary etc., the formed surface-treated aluminium-zinc hot-plated steel plate has comprehensive properties of excellent weather resistance, corrosion resistance and alkali resistance, and good machine formability etc.

Claims

1. An aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance, the plate comprising a surface comprising an environmental-friendly organic-inorganic composite protection film, the film comprising, based on the weight of the film: (A) 65-90 wt % complex matrix resin, wherein the complex matrix resin is compounded from two anionic aqueous resins (A1) and (A2), wherein anionic aqueous resin (A1) is a solvent-free aliphatic polyurethane resin based on polycarbonate diol, and anionic aqueous resin (A2) is a copolymer of polyurethane-acrylic acid and the anionic aqueous resin (A2) is not based on polycarbonate diol, wherein the weight ratio of the anionic aqueous resin (A1) to the anionic aqueous resin (A2) is 1.5-9.0; (B) 4-15 wt % organic or inorganic silicon compound selected from the group consisting of at least one of silicic acid, silicate, colloidal silica, and an organosilane coupling agent, wherein the organosilane coupling agent is selected from the group consisting of a vinyl silane coupling agent, an epoxy silane coupling agent, and a mercaptosilane coupling agent; (C) 1-8 wt % matrix resin curing agent having reactivity with a carboxyl group in the complex matrix resin, selected from one or more of an epoxy compound having multiple functional groups, an organic titanium compound, an amino resin, a polycarbodiimide compound, and an aziridine compound; (D) 0.1-3 wt % metal salt compound selected from one or more of metal compounds of zinc, aluminium, magnesium, iron, vanadium, calcium, tungsten, nickel, manganese, cobalt, titanium and cerium; (E) 2-8 wt % water-soluble zirconium compound, wherein the weight percentage thereof is calculated based on zirconia; and (F) 0.4-4 wt % lubrication auxiliary of high-density polyethylene particles or a lubrication auxiliary of polytetrafluoroethylene particles.

2. The aluminium-zinc hot-plated steel plate of claim 1, wherein the organic-inorganic composite protection film is a mono-layer structure, and the film thickness thereof ranges from 1 micron to 3 microns.

3. The aluminium-zinc hot-plated steel plate of claim 1, wherein the organic silicon compound of (B) is selected from the group consisting of at least one of silicate, colloidal silica, and an organosilane coupling agent.

4. The aluminium-zinc hot-plated steel plate of claim 1, wherein the matrix resin curing agent of (C) is the polycarbodiimide compound or the aziridine compound.

5. The aluminium-zinc hot-plated steel plate of claim 1, wherein the metal salt compound of (D) is a metal compound of vanadium or titanium, or a mixture thereof.

6. The aluminium-zinc hot-plated steel plate of claim 5, wherein the metal salt compound of (D) is vanadium (V) oxide or ammonium fluorotitanate.

7. The aluminium-zinc hot-plated steel plate of claim 1, wherein the water-soluble zirconium compound of (E) is ammonium zirconium carbonate.

8. The aluminium-zinc hot-plated steel plate of claim 1, wherein both the high-density polyethylene particles and polytetrafluoroethylene particles in said lubrication auxiliary of high-density polyethylene particles or lubrication auxiliary of polytetrafluoroethylene particles of (F) have a mean particle diameter of 0.5-2.0 microns.

9. The aluminium-zinc hot-plated steel plate of claim 1, wherein the protection film comprises: (A) 65-85 wt % said complex matrix resin; (B) 4-15 wt % said organic or inorganic silicon compound selected from the group consisting of vinyl silane coupling agent, epoxy silane coupling agent, silicate and colloidal silica; (C) 2-8 wt % said matrix resin curing agent selected from the group consisting of a polycarbodiimide compound, and an aziridine compound; (D) 0.15-1.5 wt % said metal salt compound selected from the group consisting of vanadium (V) oxide and ammonium fluorotitanate; (E) 2-8 wt % said water-soluble zirconium compound which is ammonium zirconium carbonate; and (F) 0.6-2.5 wt % said lubrication auxiliary wherein both the high-density polyethylene particles and polytetrafluoroethylene particles have a mean particle diameter of 0.5-2.0 microns.

10. The aluminium-zinc hot-plated steel plate of claim 1, wherein the protection film comprises: (A) 65-85 wt % said complex matrix resin; (B) 4-15 wt % said organic silicon compound; (C) 2-8 wt % said matrix resin curing agent; (D) 0.15-1.5 wt % said metal salt compound; (E) 2-8 wt % said water-soluble zirconium compound; and (F) 0.6-2.5 wt % said lubrication auxiliary.

11. The aluminium-zinc hot-plated steel plate of claim 10, wherein the organic silicon compound of (B) is selected from the group consisting of at least one of silicate, colloidal silica, and an organosilane coupling agent selected from the group consisting of one or more of a vinyl silane coupling agent and an epoxy silane coupling agent.

12. The aluminium-zinc hot-plated steel plate of claim 10, wherein the matrix resin curing agent of (C) is the polycarbodiimide compound or the aziridine compound.

13. The aluminium-zinc hot-plated steel plate of claim 10, wherein the metal salt compound of (D) is vanadium (V) oxide or ammonium fluorotitanate.

14. The aluminium-zinc hot-plated steel plate of claim 10, wherein the water-soluble zirconium compound of (E) is ammonium zirconium carbonate.

15. The aluminium-zinc hot-plated steel plate of claim 10, wherein both the high-density polyethylene particles and polytetrafluoroethylene particles have a mean particle diameter of 0.5-2.0 microns.

16. An environmental-friendly aqueous surface treating agent for an aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance, wherein total solid parts in an aqueous solution thereof comprises, based on the weight of the solid parts: (A) 65-90 wt % complex matrix resin, wherein the complex matrix resin is compounded from two anionic aqueous resins (A1) and (A2), wherein anionic aqueous resin (A1) is a solvent-free aliphatic polyurethane resin based on polycarbonate diol, and anionic aqueous resin (A2) is a copolymer of polyurethane-acrylic acid and the anionic aqueous resin (A2) is not based on polycarbonate diol, wherein the weight ratio of the anionic aqueous resin (A1) to the anionic aqueous resin (A2) is 1.5-9.0; (B) 4-15 wt % organic or inorganic silicon compound selected from the group consisting of at least one of silicic acid, silicate, colloidal silica, and an organosilane coupling agent, wherein the organosilane coupling agent is selected from the group consisting of a vinyl silane coupling agent, an epoxy silane coupling agent, and a mercaptosilane coupling agent; (C) 1%-8% matrix resin curing agent having reactivity with a carboxyl group in the complex matrix resin, selected from one or more of an epoxy compound having multiple functional groups, an organic titanium compound, an amino resin, a polycarbodiimide compound, and an aziridine compound; (D) 0.1%-3% metal salt compound selected from one or more of metal compounds of zinc, aluminium, magnesium, iron, vanadium, calcium, tungsten, nickel, manganese, cobalt, titanium and cerium; (E) 2-8 wt % water-soluble zirconium compound, wherein the weight percentage thereof is calculated based on zirconia; (F) 0.4-4 wt % lubrication auxiliary of high-density polyethylene particles or a lubrication auxiliary of polytetrafluoroethylene particles; and wherein the aqueous surface treating agent comprises 70-90 wt % water, based on the total weight of the aqueous surface treating agent.

17. The environmental-friendly aqueous surface treating agent of claim 16, wherein the total solid parts in the aqueous solution thereof comprises: (A) 65%-85% said complex matrix resin; (B) 4-15 wt % said organic silicon compound; (C) 2-8 wt % said matrix resin curing agent; (D) 0.15-1.5 wt % said metal salt compound; (E) 2%-8% said water-soluble zirconium compound; and (F) 0.6-2.5 wt % said lubrication auxiliary.

18. The environmental-friendly aqueous surface treating agent of claim 16, wherein said organic or inorganic silicon compound of (B) is selected from the group consisting of at least one of silicate, colloidal silica, and an organosilane coupling agent; said matrix resin curing agent of (C) is the polycarbodiimide compound or the aziridine compound; said metal salt compound of (D) is a metal compound of vanadium or titanium, or a mixture thereof; said water-soluble zirconium compound of (E) is ammonium zirconium carbonate; and both the high-density polyethylene particles and polytetrafluoroethylene particles have a mean particle diameter of 0.5-2.0 microns.

19. The environmental-friendly aqueous surface treating agent of claim 16, wherein said organic silicon compound of (B) is selected from an organosilane coupling agent of one or more of a vinyl silane coupling agent, or an epoxy silane coupling agent; and said metal salt compound of (D) is vanadium (V) oxide or ammonium fluorotitanate.

20. A method for manufacturing an aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance, the method comprising a) coating the environmental-friendly aqueous surface treating agent of claim 16 onto at least a portion of an aluminium-zinc hot-plated steel plate in one pass of roller coating, b) drying the coated plate between 80 C.180 C. until an organic-inorganic composite protection film of at least 1-3 microns is achieved, wherein an aluminium-zinc plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance with a surface thereof covered with the organic-inorganic composite protection film is obtained.

Description

PARTICULAR EMBODIMENTS

(1) The technical solutions of the present invention are further described in detail below in conjunction with the particular examples.

EXAMPLES

(2) The following examples 1-10 and comparative examples 1-7 particularly describe an aluminium-zinc plated material used and a surface cleaning method therefor, an aqueous surface treating agent, a method for treating the aluminium-zinc plated steel plate, and the performance tests of the obtained surface-treated aluminium-zinc plated steel plate.

(3) (I) Treating the Surface of the Aluminium-Zinc Plated Material:

(4) 1. Test sample plate: an aluminium-zinc hot-plated steel plate with a plate thickness of 0.5 mm, and the weight of the aluminium-zinc plated layer of 70/70 g/m.sup.2.

(5) 2. Cleaning and manufacturing method for the aluminium-zinc plated steel plate:

(6) The surface of the steel plate is first wiped using acetone or butanone, and then the steel plate is immersed into a 85% alcohol-water solution for 10 minutes ultrasonic cleaning, followed by cleaning with pure water and blow-drying. A surface treating agent is blade-coated onto the surface of the steel plate with a wire rod, and then the steel plate is dried under a condition of 80 C.-180 C., and ready for the performance test after cooling.

(7) The composition of the aqueous surface treating agent: the composition of the surface treating agents used in examples 1-10 and comparative examples 1-7 is as shown in table 1.

(8) The Materials Selected in the Present Examples

(9) (II) Manufacture of a Surface-Treated Aluminium-Zinc Hot-Plated Steel Plate:

(10) Manufacture of the aluminium-zinc hot-plated steel plate having excellent weather resistance, corrosion resistance and alkali resistance in examples 1-10 comprises coating the corresponding environmental-friendly aqueous surface treating agent shown in the above-mentioned table 1 onto the surface of the aluminium-zinc plated steel plate in one pass of roller coating, drying at a temperature as shown in table 2, and allowing the dry film thickness to be as shown in table 2 (in micron), so as to obtain a corresponding aluminium-zinc plated steel plate with the surface thereof covered with an organic-inorganic composite protection film and having excellent weather resistance, corrosion resistance and alkali resistance. Comparative examples 1-7 also use the same method above for manufacturing a corresponding surface-treated aluminium-zinc plated steel plate, and the drying temperature and dry film thickness thereof are as shown in table 2.

(11) TABLE-US-00001 TABLE 1 Water-soluble Organic silicon Matrix resin Metal salt zirconium Lubrication Complex matrix resin (A) compound (B) curing agent (C) compound (D) compound (E) auxiliary (F) The The The The The The proportion proportion proportion proportion proportion proportion Type A1/A2 of A Type of B Type of C Type of D Type of E Type of F Example 1 A1 + A2 2.3 79 B1 11.6 C1 3.9 D1 0.2 E 3.1 F1 2.2 Example 2 A1 + A2 2.3 80 B2 12.0 C1 4.0 D1 0.2 E 1.6 F1 2.2 Example 3 A1 + A2 1.9 83 B1 8.3 C1 3.3 D1 0.3 E 4.2 F1 0.9 Example 4 A1 + A2 4.0 83 B1 8.3 C1 3.3 D1 0.3 E 4.2 F1 0.9 Example 5 A1 + A2 3.0 82 B1 8.2 C2 4.0 D2 0.2 E 4.0 F2 1.6 Example 6 A1 + A2 9.0 85 B2 4.3 C1 3.4 D1 0.3 E 6.0 F2 1.0 Example 7 A1 + A2 1.5 89 B2 4.3 C1 3.2 D2 0.2 E 2.7 F1 0.6 Example 8 A1 + A2 4.0 67 B2 15.0 C1 7.5 D2 1.5 E 5.0 F1 4.0 Example 9 A1 + A2 4.0 83 B4 8.3 C1 3.3 D1 0.3 E 4.2 F1 0.9 Example 10 A1 + A2 1.5 89 B5 4.3 C1 3.2 D2 0.2 E 2.7 F1 0.6 Comparative A1 + A2 4.0 69 B2 23.9 C1 2.8 D1 0.2 E 3.4 F1 0.7 Example 1 Comparative A1 + A2 4.0 77 B1 7.5 C1 3.1 D1 0.2 E 11.4 F1 0.8 Example 2 Comparative A1 79 B1 11.2 C1 4.0 D1 0.2 E 4.0 F2 1.6 Example 3 Comparative A2 79 B1 11.2 C1 4.0 D1 0.2 E 4.0 F2 1.6 Example 4 Comparative A1 + A2 1.5 85 B2 9.0 C2 3.4 E 1.7 F1 0.9 Example 5 Comparative A1 + A2 3.0 86 B1 8.6 C1 3.4 D1 0.3 F1 1.7 Example 6 Comparative A1 + A2 3.0 85 B3 8.0 C1 3.3 D1 0.3 E 1.7 F1 1.7 Example 7 Note: the proportion of A-F: the weight percentage of A-F in the solid parts of the treating agent; A1/A2 represents the weight ratio of the two; A1 is a solvent-free aqueous aliphatic anionic polyurethane resin based on polycarbonate diol, Acure6171 resin purchased from Shanghai Yuanhe Chemical Co., Ltd; A2 is a copolymer of an anionic aqueous polyurethane-acrylic acid; B1 is vinyl trimethoxysilane; B2 is glycidoxypropyltrimethoxysilane; B3 is aminopropyltriethoxysilane; B4 is colloidal silica; and B5 is potassium silicate; C1 is polycarbodiimide; and C2 is aziridine; D1 is a V compound, in particular vanadium (pentavalence) oxide; and D2 is a Ti compound, in particular ammonium fluorotitanate; F1 is a high-density polyethylene wax; F2 is a mixed system of a polyethylene wax and a polytetrafluoroethylene wax, the weight ratio thereof being 3:7.

(12) (III) Performance Test of the Surface-Treated Aluminium-Zinc Hot-Plated Steel Plate:

(13) The weather resistance, corrosion resistance, alkali resistance, processability and storage stability of the surface-treated aluminium-zinc hot-plated steel plate in examples 1-10 and comparative examples 1-7 are as shown in table 3:

(14) 1. Weather Resistance

(15) A sample plate was placed in a UV aging test chamber (UVB-313 lamp tube), wherein the cycle period was set to be 8 h, with 4 h UV-irradiation at a black panel temperature of 60 C.3 C., and 4 h condensation at a black panel temperature of 50 C.3 C.; and after 600 h, the appearance of the sample plate was observed and the gloss retention rate thereof was measured, and the evaluation standard is as follows:

(16) : the appearance of the sample plate has no significant change, and the gloss retention rate is more than or equal to 70%;

(17) : the appearance of the sample plate has a slight change, and the gloss retention rate is more than or equal to 50% and less than 70%;

(18) : the appearance of the sample plate has a remarkable change, and the gloss retention rate is more than or equal to 30% and less than 50%;

(19) : the appearance of the sample plate has a serious change, and the gloss retention rate is less than 30%.

(20) 2. Corrosion Resistance

(21) A plane plate was subjected to a salt spray test, wherein the test standard is ASTM B 117, the test time was 240 hours, and the evaluation standard is as follows:

(22) : the white rust area rate is less than or equal to 5%;

(23) : the white rust area rate is more than 5% and less than or equal to 10%;

(24) : the white rust area rate is more than 10% and less than or equal to 50%;

(25) : the white rust area rate is more than 50%.

(26) 3. Alkali Resistance

(27) A test sample plate was immersed in a 0.1% sodium hydroxide solution for 1 hour, and taken out for blow-drying and then measured for the change in colour difference values (E*) before and after immersing, and the evaluation standard is as follows:

(28) : the colour difference value E* is less than or equal to 3.0;

(29) : the colour difference value E* is more than 3.0 and less than or equal to 6.0;

(30) : the colour difference value E* is more than 6.0 and less than or equal to 9.0;

(31) : the colour difference value E* is more than 9.0.

(32) 4. Processability

(33) 4.1 After performing a T-bend test on the test sample plate, a tape stripping method was used to evaluate the peeling degree of the processed skin film, and the evaluation standard is as follows:

(34) : 2T, the skin film has no peeling;

(35) : 3T, the skin film has no peeling;

(36) : 4T, the skin film has no peeling;

(37) : 5T, the skin film has no peeling.

(38) 4.2 A draw-bead method was used for the test, and the test conditions were: a fixed pressure under bead of 3 KN, a pressure head diameter of 9.6 mm, and a drawing speed of 200 mm/min. The appearance was observed after drawing, and the evaluation method is as follows:

(39) : the appearance has no change;

(40) : a small amount of black points on the appearance;

(41) : relatively more obvious black stripes on the appearance;

(42) : the overall appearance becomes black.

(43) 5. Storage Stability

(44) A treating solution was placed at room temperature, the change of the solution was observed after 90 days, and the evaluation method is as follows:

(45) : no change;

(46) : slightly thickening (functioning normally);

(47) : seriously thickening;

(48) : gel.

(49) TABLE-US-00002 TABLE 2 The treating processes of each example and comparative example Thickness of the protection film Drying (microns) temperature ( C.) Example 1 1.2 120 Example 2 1.4 90 Example 3 1.5 130 Example 4 1.8 130 Example 5 2.0 120 Example 6 2.1 120 Example 7 2.3 120 Example 8 2.8 160 Example 9 1.8 130 Example 10 2.3 120 Comparative Example 1 0.8 80 Comparative Example 2 1.2 120 Comparative Example 3 1.2 120 Comparative Example 4 1.6 130 Comparative Example 5 1.9 130 Comparative Example 6 2.3 120 Comparative Example 7 2.7 120

(50) TABLE-US-00003 TABLE 3 The performance of each example and comparative example Weather Corrosion Alkali Processability resis- resis- resis- T Storage tance tance tance bend Drawing stability Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative Example 1 Comparative X Example 2 Comparative Example 3 Comparative Example 4 Comparative X Example 5 Comparative Example 6 Comparative X Example 7

(51) The performance effects of the surface-treated aluminium-zinc hot-plated steel plate of examples 1-10 and comparative examples 1-7 can be seen from table 2, wherein the excessive addition of the silane coupling agent in comparative example 1 causes the corrosion resistance, alkali resistance and solution stability to become less favourable; in comparative example 2, the excessive addition of the water-soluble zirconium compound results in a rapid decrease in the stability of the solution; in comparative examples 3 and 4, the matrix resin is not subjected to compounding, which respectively leads to a decrease in the weather resistance and the corrosion resistance; comparative examples 5 and 6 respectively lack the metal salt compound and the aqueous zirconium compound, which causes the weather resistance, corrosion resistance and alkali resistance to decrease to various degrees; and in comparative example 7, the amino silane coupling agent is used, and the stability of the solution becomes less favourable. However, the surface treating agent used for treating the surface of the aluminium-zinc hot-plated steel plate in examples 1-8 of the present invention is excellent in storage stability, and the aluminium-zinc hot-plated steel plate treated with this surface treating agent all shows good properties of weather resistance, corrosion resistance, alkali resistance and processability.

(52) The surface-treated aluminium-zinc hot-plated steel plate of the present invention and the surface treating agent used therefor still have excellent weather resistance, corrosion resistance, alkali resistance, and processability etc. without containing chromium, which has a great practical effect in the social problems of environmental protection and reproducibility etc.