KR101674818B1 - Coating composites containing trivalent chromium, zinc-based metal plated steel sheet using the same and coating method - Google Patents
Coating composites containing trivalent chromium, zinc-based metal plated steel sheet using the same and coating method Download PDFInfo
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- KR101674818B1 KR101674818B1 KR1020150101386A KR20150101386A KR101674818B1 KR 101674818 B1 KR101674818 B1 KR 101674818B1 KR 1020150101386 A KR1020150101386 A KR 1020150101386A KR 20150101386 A KR20150101386 A KR 20150101386A KR 101674818 B1 KR101674818 B1 KR 101674818B1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/24—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds
- C23C22/30—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing hexavalent chromium compounds containing also trivalent chromium
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
- C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium
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Abstract
Description
The present invention relates to a coating composition containing trivalent chromium, a zinc-based plated steel sheet using the same, and a method of coating zinc plated steel sheet.
Generally, zinc plated steel sheets have been widely used for construction materials, household appliances, and automotive anti-corrosive steel sheets, due to the excellent function of the metal material of the plated layer. However, white rust is generated on the surface of the zinc-based plated steel sheet in an electrolyte such as salt contained in the air or in a high temperature and high humidity environment, corrosion occurs, and the plated steel is blackened. As a means of preventing the corrosion or blackening of the plated steel, a post-treated plated steel sheet is produced using a post-treatment solution.
However, if the after-treatment coated steel sheet is processed into a pipe, if the post-treatment coating is not rigid, slippage may occur during processing or the processed parts can not be transferred properly, resulting in lower productivity. In addition, if a pressing process is performed to produce a machined part having a certain shape, the coating film peels off in the case of deep processing, or a processing blackening phenomenon occurs on the surface, thereby deteriorating the surface appearance. Such surface peeling or scratching promotes further corrosion in the atmospheric environment, resulting in reduced durability of the product.
Traditionally, hexavalent chromium post-treatment and chromium-free post-treatment are mainly performed to solve such a phenomenon. However, in the case of hexavalent chromium post-treatment, fatal chromic acid vapors are generated in the process during the process, and when hexavalent chromium ions enter the groundwater or river, they cause fatal environmental pollution.
On the other hand, the chromium-free post-treatment should be carried out at a high temperature of 90 ° C or higher in order to cure the coating after coating in the post-treatment. In addition, the chrome-free inorganic coating shows a tendency to heat relative to the existing product in terms of corrosion resistance, and the coating peels off with the phenomenon of peeling of the coating during deep processing, and further, blackness after processing due to lack of lubricity of the surface coating itself do.
Accordingly, chromium post-treatment using trivalent chromium has been recognized to be the most effective and efficient.
Japanese Patent Publication No. 63-015991 discloses a method of improving the corrosion resistance and surface appearance of a galvanized steel sheet by a chromate treatment using a solution containing trivalent chromium, fluoride, organic acid, inorganic acid, cobalt sulfate, and the like However, it is necessary to solve the environmental problems caused by the addition of fluoride.
Japanese Patent Application Laid-Open No. 2000-509434 discloses a surface treatment liquid for preventing surface corrosion of a galvanized steel sheet, which contains 5 to 100 g / L of tricalcium chloride, a nitric acid group, an organic acid, cobalt and the like. However, Unstable and a large amount of sludge is generated.
The surface treatment liquids of U.S. Pat. Nos. 4578122 and 5368655 contain low concentrations of ternary chromium, organic acids and Ni, but have a problem of corrosion resistance compared with conventional chrome treatment materials.
The present invention provides a zinc-based plated steel sheet excellent in toughness, corrosion resistance, black coloration and solvent resistance by providing a coating composition comprising a trivalent chromium as a main component harmless to the human body and applying it to a zinc plated steel sheet.
According to one embodiment of the present invention, there is provided a process for producing a metal oxide, which comprises, on a solid basis, 47.06 to 68.97% by weight of a trivalent chromium compound, 2.70 to 14.29% by weight of silica sol, 12.27 to 35.87% by weight of an oxidizing agent, 1.35 to 9.52% by weight of a fluorotitanate compound, 0.25 to 2.48 wt.% Of dihydrogen phosphate, 0.25 to 2.48 wt.% Of phosphoric acid compound, 0.25 to 2.00 wt.% Of metal acetylacetone, and 0.25 to 0.75 wt.% Of sulfonic acid.
The trivalent chromium compound is nitric acid, chromium (Cr (NO 3) 3) , sulfuric acid, chromium (Cr 2 (SO 4) 3 ), sulfate, chromium potassium (CrK (SO 4) 2) , chloride, chromium (CrCl 3), ethyl chromium (Cr (CH 3 CO 2) 3) and oxalic acid chrome (Cr 2 (C 2 O 4 ) 3) as may be at least one selected from the group consisting of.
The oxidizing agent may be a metal nitrate, a metal sulfate or a mixture thereof.
The metal nitrate is selected from the group consisting of zinc nitrate (Zn (NO 3 ) 2 ), aluminum nitrate (Al (NO 3 ) 3 ), magnesium nitrate (Mg (NO 3 ) 2 ), potassium nitrate (KNO 3 ) 3 ) 2 ).
The metal sulfate is zinc sulfate (ZnSO 4), aluminum sulfate (Al 2 (SO 4) 3 ), magnesium sulfate (MgSO 4), potassium sulfate (K 2 SO 4) and calcium sulfate (CaSO 4) from the group consisting of selected It can be more than one.
The fluorotitanate compound may be at least one selected from the group consisting of hydrofluoro titanic acid (H 2 TiF 6 ), potassium fluoro titanate (K 2 TiF 6 ), sodium fluoro titanate (Na 2 TiF 6 ), and ammonium fluoro titanate ((NH 4 ) 2 TiF 6 ).
The metal die hydrogenphosphate is aluminum die-hydrogen phosphate (Al (H 2 PO 4) 3), magnesium di hydrogen phosphate (Mg (H 2 PO 4) 2) and calcium di hydrogen phosphate (Ca (H 2 PO 4 ) 2 ).
The phosphate compound is a second sodium phosphate (Na 2 HPO 4), phosphoric acid ammonium ((NH 4) 2 HPO 4), phytic acid, trisodium phosphate (Na 3 PO 4), phosphate, ammonium ((NH 4) H 2 PO 4 ) and triammonium phosphate ((NH 4 ) 3 PO 4 ).
The metal acetylacetone may be at least one selected from the group consisting of zirconium acetylacetonate, aluminum acetylacetonate, iron acetylacetonate, zinc acetylacetonate and nickel acetylacetonate.
The sulfonic acid may be at least one selected from the group consisting of methanesulfonic acid (MSA), ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid and benzenesulfonic acid.
The coating composition may have a pH of 1.0 to 4.0.
According to another embodiment of the present invention, there is provided a zinc-based plated steel sheet comprising a steel sheet, a zinc-based plated layer formed on one or both surfaces of the steel sheet, and a coating layer formed on the plating layer, wherein the coating layer comprises the coating composition .
The coating layer may have an adhesion amount of 150 to 600 mg / m < 2 >
According to another embodiment of the present invention, there is provided a zinc-based coated steel sheet coating method comprising coating a zinc-based galvanized steel sheet with the coating composition to form a coating layer, and drying the coating layer.
The coating may be controlled such that the coating layer has an adhesion amount of 150 to 600 mg / m < 2 >.
The coating can be carried out by any one coating method selected from roll coating, spraying, immersion, spraying and immersion squeezing.
The drying can be controlled at a temperature of 50 to 80 캜 based on the steel sheet surface maximum temperature (PMT).
The zinc-plated steel sheet treated with the coating composition containing trivalent chromium according to the present invention has an effect of not only being excellent in toughness, corrosion resistance, black coloration and solvent resistance but also preventing the damage to the human body and the environmental pollution .
1 is a photograph of the results of evaluating the solvent resistance of Examples 1, 2, 6 and 7 and Comparative Examples 3 to 6 and 12.
Fig. 2 is a photograph of the results of blackening evaluation of Examples 8 to 10, 12 to 14, and Comparative Examples 2 and 4;
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.
The coating composition according to one embodiment of the present invention comprises, on a solid basis, 47.06 to 68.97 wt% of a trivalent chromium compound, 2.70 to 14.29 wt% of silica sol, 12.27 to 35.87 wt% of an oxidizing agent, 1.35 to 9.52 wt% of a fluorotitanate compound , 0.25 to 2.48 wt% of metal dihydrogen phosphate, 0.25 to 2.48 wt% of phosphoric acid compound, 0.25 to 2.00 wt% of metal acetylacetone, and 0.25 to 0.75 wt% of sulfonic acid.
The zinc-plated steel sheet treated with the coating composition containing trivalent chromium according to the present invention has an effect of not only being excellent in toughness, corrosion resistance, black coloration and solvent resistance but also preventing the damage to the human body and the environmental pollution . The ductility refers to a property that the steel sheet is easy to manufacture with a pipe or an easy degree. The higher the friction coefficient is, the better the pipe workability becomes.
The trivalent chromium compound has self-healing effect and self-lubrication similar to hexavalent chromium and is superior to other inorganic substances in terms of toughness and corrosion resistance. The content of the trivalent chromium compound is preferably 47.06 to 68.97% by weight based on the solid content of the entire composition. When the content is less than 47.06% by weight, the corrosion resistance and toughness are poor. When the content is more than 68.97% by weight, The effect of improving physical properties is insignificant and not economical.
The three types of the chromium compound is not particularly limited and, for example, nitric acid, chromium (Cr (NO 3) 3) , sulfuric acid, chromium (Cr 2 (SO 4) 3 ), sulfate, chromium potassium (CrK (SO 4) 2 ), Chromium chloride (CrCl 3 ), chromium acetate (Cr (CH 3 CO 2 ) 3 ) and chromium oxalate (Cr 2 (C 2 O 4 ) 3 )
The silica sol is an auxiliary binder for enhancing adhesion between the zinc-based plating surface and the coating layer, and the content of the silica sol is preferably 2.70 to 14.29% by weight based on the solid content of the entire composition. When the content of the silica sol is less than 2.70 wt%, the blackness and toughness are poor. When the content of the silica sol exceeds 14.29 wt%, gelation of silicon and chromium proceeds and the solution stability is weakened.
The oxidizing agent is preferably a metal nitrate salt, a metal sulfate salt or a mixture thereof, and the metal may function to form an insoluble compound by reacting with free phosphoric acid. On the other hand, the content of the oxidizing agent is preferably 12.27 to 35.87% by weight based on the solid content of the whole composition. When the content is less than 12.27% by weight, the blackness and toughness are inferior. When the content is more than 35.87% by weight, gelation phenomenon occurs and the solution stability is weakened.
Examples of the metal nitrate salt include zinc nitrate (Zn (NO 3 ) 2 ), aluminum nitrate (Al (NO 3 ) 3 ), magnesium nitrate (Mg 3) 2), potassium nitrate (KNO 3) and calcium nitrate (Ca (NO 3) 2) with preferably at least one selected from the group consisting of, wherein the metal sulfate is zinc sulfate (ZnSO 4), aluminum sulfate (Al 2 ( SO 4 ) 3 ), magnesium sulfate (MgSO 4 ), potassium sulfate (K 2 SO 4 ) and calcium sulfate (CaSO 4 ).
The fluorotitanate compound may be added to the coating composition in order to increase the initial etching property of the zinc plated steel sheet and increase the adhesion with the plating surface to improve the corrosion resistance and the process blackness. On the other hand, the content of the fluorotitanate compound is preferably 1.35 to 9.52% by weight based on the solid content of the entire composition. When the content is less than 1.35% by weight, it is disadvantageous in blackness and toughness. When the content is more than 9.52% by weight, gelation of the solution is accelerated.
The kind of the fluorotitanate compound is not particularly limited, and examples thereof include hydrofluoro titanic acid (H 2 TiF 6 ), potassium fluoro titanate (K 2 TiF 6 ), sodium fluoro titanate (Na 2 TiF 6 ) And ammonium fluorotitanate ((NH 4 ) 2 TiF 6 ).
The metal dihydrogen phosphate is added to the coating composition of the present invention as a supplementary corrosion-resistant additive. Phosphate contained in the metal dihydrogen phosphate reacts with zinc, magnesium or calcium to form an insoluble compound , It can serve to maximize the corrosion resistance of the hot-dip galvanized steel sheet.
The content of the metal dihydrogen phosphate is preferably 0.25 to 2.48 wt% based on the solid content of the entire composition. When the content of the metal dihydrogen phosphate is less than 0.25 wt%, the corrosion resistance, brittleness and blackening are insufficient. When the content is more than 2.48 wt% The film adhesion strength is lowered and the toughness is weakened.
The kind of the metal dihydrogen phosphate is not particularly limited, and examples thereof include aluminum dihydrogen phosphate (Al (H 2 PO 4 ) 3 ), magnesium dihydrogen phosphate (Mg (H 2 PO 4 ) 2 ) And calcium dihydrogen phosphate (Ca (H 2 PO 4 ) 2 ).
The phosphoric acid compound is added to the coating composition of the present invention as an auxiliary adhesion promoter and an auxiliary toughening agent, and the content of the phosphoric acid compound is preferably 0.25 to 2.48 wt% based on the solid content of the entire composition. When the content is less than 0.25% by weight, the toughness and blackening tend to be insufficient. When the content is more than 2.48% by weight, the film exhibits properties for heat resistance at solvent resistance.
The type of the phosphate compound is not particularly limited and, for example, a second sodium phosphate (Na 2 HPO 4), phosphoric acid ammonium ((NH 4) 2 HPO 4 ), phytic acid, trisodium phosphate (Na 3 PO 4 ), ammonium monophosphate ((NH 4 ) H 2 PO 4 ), and triammonium phosphate ((NH 4 ) 3 PO 4 ).
The metal acetylacetone is included in the coating composition of the present invention in order to increase the density of the thin film by reacting with the trivalent chromium compound and the silica sol. The content of the metal acetylacetone is, based on the solid content of the entire composition, And preferably 0.25 to 2.00 wt%. When the content is less than 0.25% by weight, the blackness and toughness are insufficient. When the content is more than 2.00% by weight, gelation of the solution occurs.
The kind of the metal acetylacetone is not particularly limited, but is preferably at least one selected from the group consisting of zirconium acetylacetonate, aluminum acetylacetonate, iron acetylacetonate, zinc acetylacetonate and nickel acetylacetonate .
The sulfonic acid is an auxiliary etchant for increasing the adhesion between the zinc-based plated layer and the coating layer, and the content of the sulfonic acid is preferably 0.25 to 0.75% by weight based on the solid content of the entire composition. When the content is less than 0.25% by weight, the blackness and toughness are poor. When the content is more than 0.75% by weight, whitening occurs on the coating surface.
The type of the sulfonic acid is not particularly limited and may be, for example, at least one selected from the group consisting of methanesulfonic acid (MSA), ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid and benzenesulfonic acid.
According to another embodiment of the present invention, it is preferable to control the pH of the coating composition to be 1.0 to 4.0. If the pH is less than 1.0, the coated steel sheet is poor in toughness and corrosion resistance. If the pH is more than 4.0, the blackening and solvent resistance of the coated steel sheet may be poor.
The coating composition of the present invention comprises, on a solid basis, 47.06 to 68.97 wt% of a trivalent chromium compound, 2.70 to 14.29 wt% of silica sol, 12.27 to 35.87 wt% of an oxidizing agent, 1.35 to 9.52 wt% of a fluorotitanate compound, 0.25 to 2.48 wt.% Of phosphoric acid, 0.25 to 2.48 wt.% Of phosphoric acid compound, 0.25 to 2.00 wt.% Of metal acetylacetone and 0.25 to 0.75 wt.% Of sulfonic acid, and the zinc- Corrosion resistance, black coloration and solvent resistance, as well as preventing damage to human bodies and environmental pollution.
According to another embodiment of the present invention, there is provided a galvanized steel sheet comprising a steel sheet, a zinc-based plated layer formed on one or both surfaces of the steel sheet, and a coating layer formed on the plating layer, can do.
The coating layer preferably has a dry coating adhesion amount of 150 to 600 mg / m 2. When the dry coating adhesion amount is less than 150 mg / m 2 , the corrosion resistance is poor. When the coating adhesion amount exceeds 600 mg / m 2, do.
According to another embodiment of the present invention, there is provided a zinc-based coated steel sheet coating method comprising the steps of: coating the above-described coating composition on a zinc-based coated steel sheet to form a coating layer; and drying the coating layer.
The coating is preferably controlled such that the dry film coating weight of the coating layer is 150 to 600 mg / m 2, wherein the dry film coating weight is less than 150 mg / m 2 and the corrosion resistance is inferior, 600 mg / m 2 if it exceeds the coated steel strip Powdering occurs during processing.
The coating method is not particularly limited as long as it is a conventional coating method. For example, the coating method is preferably performed by any one coating method selected from roll coating, spraying, immersion, spraying, and immersion spouting.
In the galvanized steel sheet coating method according to an embodiment of the present invention, drying is preferably controlled at a temperature of 50 to 80 ° C on the basis of the maximum surface temperature (PMT) of the steel sheet. When the temperature is less than 50 ° C, sufficient corrosion resistance and coarseness If the temperature is higher than 80 DEG C, drying will not occur any longer and the economical efficiency will be lowered.
Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.
Example
As the composition of the coating composition, chromium nitrate is used as the trivalent chromium compound, zinc nitrate is used as the oxidizing agent, hydrofluorotitanic acid (H 2 TiF 6 ) is used as the fluorotitanate compound, and aluminum dihydrofibromide is used as the metal dihydrogen phosphate hydrogen phosphate (Al (H 2 PO 4) 3)), a phosphate compound is the phytic acid, the metal acetylacetonate is zirconium acetylacetonate and the sulfonic acid comprises methanesulfonic acid, and the components are mixed in an amount shown in Table 1 Respectively. The pH of the mixed solution was adjusted to 2.0 to prepare a coating composition.
The above-mentioned coating composition was coated on a hot-dip galvanized steel sheet having a plating amount of 60 g / m 2 , and then dried at a temperature of 60 ° C. The dried coated steel sheet was aged at room temperature for 24 hours to prepare a chromate treated galvanized steel sheet having a dried coating adhesion amount of 300 mg / m 2 .
The solution stability was evaluated with the above coating composition, and the chromate-treated zinc-coated steel sheets were evaluated for blackness, solvent resistance, corrosion resistance and toughness, and the evaluation results are shown in Table 2.
The evaluation methods of the solution stability, blackening resistance, solvent resistance, corrosion resistance and toughness are as follows.
≪ Evaluation of solution stability &
The stability of the solution was evaluated by storing the sample in an oven maintained at 50 캜 for 3 days to measure the degree of sludge and gel formation. The evaluation criteria are as follows.
○: Solution which does not generate sludge and gel
X: Solution in which sludge is generated
<Evaluation of Black Degeneration>
The evaluation of black coloration (high temperature and high humidity) was classified into four types according to the discoloration state of the surface after a lapse of 120 hours in a constant temperature and humidity chamber maintained at 50 ° C. and a relative humidity (RH) of 95% Respectively.
⊚: The color difference (DE) in which the coating film is discolored is 2.0 or less
?: The color difference (DE) of the coating film was 2.0 to 3.0
DELTA: color difference (DE) in which the coating film is discolored is 3.0 to 5.0
X: a color difference (DE) in which the coating film is discolored is 5.0 or more
<Evaluation of solvent resistance>
The evaluation of solvent resistance was carried out by transferring 1 kgf of methyl ethyl ketone (MEK) to the gauze agent 50 times, and the color difference of the coating film was discolored. The evaluation criteria were as follows
⊚: The color difference (DE) in which the coating film is discolored is 1.0 or less
?: The color difference (DE) of the coating film was 1.0 to 2.0
DELTA: color difference (DE) in which the coating film was discolored was 2.0 to 3.0
X: Color discrepancy (DE) of the coating film is 3.0 or more
≪ Evaluation of corrosion resistance &
The corrosion resistance was evaluated by a salt spray tester (SST). After 120 hours, the area of the white rust was evaluated in terms of%. The conditions of salt water sprayer was done using 5% NaCl in pure water temperature was 35 ℃, spraying pressure of 1kgf / cm 2, spray amount was set at 80ml / cm 2 / day. The evaluation criteria are as follows.
◎: White steel of steel sheet is within 5%
○: 5-25%
?: 25 to 50% of white rust of steel sheet
X: Greater than 50% of white rust
<Bondability evaluation>
The toughness evaluation is performed with a tribometer, and the friction coefficient is measured in each cycle by repeatedly evaluating the friction, and is based on the value of the friction coefficient at 60 cycles. At this time, the diameter of the tip of the tribometer is 8 mm, the edge R = 1 and the descending force is 494 N, and the measurement is carried out while the evaluation sample is immersed in the tubular oil. The evaluation criteria are as follows.
?: Friction coefficient value exceeded 0.120
?: Friction coefficient value is 0.100 to 0.120
?: Friction coefficient value is 0.080 to 0.100
X: Friction coefficient value less than 0.080
* The content of the composition is based on the solid content
As shown in Table 2, Examples 1 to 23 satisfying the composition and content conditions of the present invention had excellent black discoloration, solvent resistance, corrosion resistance and toughness, excellent solution stability, and excellent quality in terms of solution storage .
1 is a photograph of the results of evaluating the solvent resistance of Examples 1, 2, 6, 7, and Comparative Examples 3 to 6, and FIG. 2 is a photograph showing Examples 8 to 10, 12 to 14, The results of the black degeneration evaluations of Examples 2 and 4 are shown in FIG. 1 and FIG. 2, and the results of the solvent resistance and black deformation test of Examples and Comparative Examples were confirmed.
Comparative Examples 1, 4, and 5 were prepared in a composition deviating from the content of the trivalent chromium compound of the present invention, resulting in poor solution stability, blackness, corrosion resistance, or toughness. Comparative Examples 2 and 3 show the content of the silica sol of the present invention There is a problem in that the solution stability, black coloration or brittleness tends to be generated.
Comparative Examples 4 and 5 were prepared in a composition deviating from the content of the oxidizing agent of the present invention, Comparative Examples 5 and 6 were prepared in a composition deviating from the content of the fluorotitanate compound of the present invention, There was a problem for.
Comparative Examples 7 and 8 were prepared with a composition deviating from the content of the metal dihydrogen phosphate of the present invention and Comparative Examples 9 and 10 were prepared with a composition deviating from the content of the phosphoric acid compound of the present invention, There was a problem for openness.
Comparative Examples 11 and 12 were prepared in a composition deviating from the content of the metal acetylacetone of the present invention, and there was a problem that the solution stability or the blackening occurred.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.
Claims (17)
The trivalent chromium compound is nitric acid, chromium (Cr (NO 3) 3) , sulfuric acid, chromium (Cr 2 (SO 4) 3 ), sulfate, chromium potassium (CrK (SO 4) 2) , chloride, chromium (CrCl 3), ethyl chromium (Cr (CH 3 CO 2 ) 3 ) and chromium oxalate (Cr 2 (C 2 O 4 ) 3 ).
Wherein the oxidizing agent is a metal nitrate salt, a metal sulfate salt or a mixture thereof.
The metal nitrate is selected from the group consisting of zinc nitrate (Zn (NO 3 ) 2 ), aluminum nitrate (Al (NO 3 ) 3 ), magnesium nitrate (Mg (NO 3 ) 2 ), potassium nitrate (KNO 3 ) 3 ) 2 ).
The metal sulfate is zinc sulfate (ZnSO 4), aluminum sulfate (Al 2 (SO 4) 3 ), magnesium sulfate (MgSO 4), potassium sulfate (K 2 SO 4) and calcium sulfate (CaSO 4) from the group consisting of selected At least one coating composition.
The fluorotitanate compound may be at least one selected from the group consisting of hydrofluoro titanic acid (H 2 TiF 6 ), potassium fluoro titanate (K 2 TiF 6 ), sodium fluoro titanate (Na 2 TiF 6 ), and ammonium fluoro titanate ((NH 4 ) 2 TiF 6) one or more coating compositions selected from the group consisting of.
The metal die hydrogenphosphate is aluminum die-hydrogen phosphate (Al (H 2 PO 4) 3), magnesium di hydrogen phosphate (Mg (H 2 PO 4) 2) and calcium di hydrogen phosphate (Ca (H 2 PO 4 ) 2 ).
The phosphoric acid compounds other than the metal dihydrogen phosphate may be selected from the group consisting of sodium diphosphate (Na 2 HPO 4 ), ammonium dihydrogenphosphate ((NH 4 ) 2 HPO 4 ), phytic acid, sodium triphosphate (Na 3 PO 4 ) one ammonium ((NH 4) H 2 PO 4) and tricalcium phosphate of ammonium ((NH 4) 3 PO 4 ) with one or more coating compositions selected from the group consisting of.
Wherein the metal acetylacetone is at least one selected from the group consisting of zirconium acetylacetonate, aluminum acetylacetonate, iron acetylacetonate, zinc acetylacetonate and nickel acetylacetonate.
Wherein the sulfonic acid is at least one selected from the group consisting of methanesulfonic acid (MSA), ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid and benzenesulfonic acid.
Wherein the coating composition has a pH of 1.0 to 4.0.
A zinc plated layer formed on one side or both sides of the steel sheet; And
And a coating layer formed on the plating layer,
Wherein the coating layer comprises the coating composition according to any one of claims 1 to 11.
Wherein the coating layer has a dry coating adhesion amount of 150 to 600 mg / m 2 .
And drying the coating layer.
Wherein the coating is controlled so that an adhesion amount of a dry film of the coating layer is 150 to 600 mg / m 2 .
Wherein the coating is carried out by any one coating method selected from roll coating, spraying, immersion, spraying, and immersion spiking.
Wherein the drying is controlled at a temperature of 50 to 80 占 폚 based on a maximum surface temperature (PMT) of the steel sheet.
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Cited By (3)
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CN110229549A (en) * | 2019-05-14 | 2019-09-13 | 全球能源互联网研究院有限公司 | A kind of high-temperature insulation composite, insulating coating and its preparation method and application |
CN111074255A (en) * | 2019-12-05 | 2020-04-28 | 刘广付 | Metal surface pretreatment agent and preparation method and application thereof |
CN111601911A (en) * | 2017-11-13 | 2020-08-28 | Posco公司 | Trivalent chromium-containing solution composition for treating surface of steel sheet, hot-dip galvanized steel sheet surface-treated with the composition, and method for manufacturing hot-dip galvanized steel sheet |
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KR20080017318A (en) * | 2005-05-27 | 2008-02-26 | 니혼 파커라이징 가부시키가이샤 | Chemical treating liquid for metal and treating method |
JP2015038255A (en) * | 2014-11-27 | 2015-02-26 | 日本表面化学株式会社 | Protective film formation method of metal and protective film formation treatment agent |
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KR20080017318A (en) * | 2005-05-27 | 2008-02-26 | 니혼 파커라이징 가부시키가이샤 | Chemical treating liquid for metal and treating method |
JP2015038255A (en) * | 2014-11-27 | 2015-02-26 | 日本表面化学株式会社 | Protective film formation method of metal and protective film formation treatment agent |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
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CN111601911A (en) * | 2017-11-13 | 2020-08-28 | Posco公司 | Trivalent chromium-containing solution composition for treating surface of steel sheet, hot-dip galvanized steel sheet surface-treated with the composition, and method for manufacturing hot-dip galvanized steel sheet |
CN111601911B (en) * | 2017-11-13 | 2022-06-14 | Posco公司 | Surface treatment solution composition, surface-treated alloyed hot-dip galvanized steel sheet, and method for producing same |
US11634818B2 (en) | 2017-11-13 | 2023-04-25 | Posco Co., Ltd | Solution composition containing trivalent chromium for surface treatment of steel sheet, galvanized steel sheet surface—treated with same, and method for manufacturing galvanized |
CN110229549A (en) * | 2019-05-14 | 2019-09-13 | 全球能源互联网研究院有限公司 | A kind of high-temperature insulation composite, insulating coating and its preparation method and application |
CN111074255A (en) * | 2019-12-05 | 2020-04-28 | 刘广付 | Metal surface pretreatment agent and preparation method and application thereof |
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