JP5338195B2 - Surface-treated galvanized steel sheet and method for producing the same - Google Patents

Description

  The present invention relates to a surface-treated zinc-based plated steel sheet.

  Examples of the zinc-based plated steel sheet used in the present invention include galvanized steel sheet, zinc-nickel plated steel sheet, zinc-iron plated steel sheet, zinc-chromium plated steel sheet, zinc-aluminum plated steel sheet, zinc-titanium plated steel sheet, zinc- It is an electroplating such as a magnesium-plated steel sheet and a zinc-manganese-plated steel sheet, a hot dipped plating, and a vapor-deposited steel sheet, and is not particularly limited as long as it is a steel sheet plated with zinc.

  As one of chemical conversion treatments for the purpose of rust prevention on the surface of metal materials, chromate treatment has been widely used for a long time. In chromate treatment, when a metal material is immersed in a treatment liquid containing hexavalent chromium as a main component, a part of the hexavalent chromium is reduced, and a gel-like composite hydrated oxide containing hexavalent chromium and trivalent chromium as main components. A film (chromate film) is formed. The chromate film has both excellent anticorrosion performance (corrosion resistance) and self-healing performance, and excellent paint adhesion.

  Although the chromate film has the above-mentioned excellent performance, the demand for chemical conversion treatment (non-chromate treatment) that does not use chromium is rapidly increasing with the recent increase in awareness of environmental problems.

  Non-chromate treatment techniques that have been studied so far can be broadly classified into inorganic coatings, organic coatings, and organic-inorganic composite coatings (mixed coatings). Inorganic coatings include coatings that use metal oxides such as ceria, alumina, and titania, and metal salts such as molybdate, and phosphate coatings that have been widely used so far. Is a processing technology that focuses on Many organic coatings aim to suppress the progress of corrosion using a barrier effect and adhesion by a resin coating, and a chelate reaction to supplement the self-repairing action of the chromate coating. For example, there are a chelate treatment film, a resin film, a silane coupling treatment film, a conductive polymer film, and the like. The organic-inorganic composite film is a film in which the barrier effect and adhesion are improved by mixing an organic resin film having a functional group and an inorganic material such as a phosphate, silica, or a metal salt compound.

  On the other hand, chromate treatment has been performed on galvanized steel sheets, but non-chromate treatment of the above-described inorganic coating, organic coating, and organic-inorganic composite coating has been studied.

  For example, in Patent Document 1, a zinc-plated steel plate or a zinc alloy-plated steel plate is used as a base material, and oxides or hydroxides of valve metals (valve metals) such as Ti, Zr, Hf, V, Nb, Ta, Mo, and W are used. A chemical conversion treatment film (inorganic film) in which a product and a fluoride coexist is disclosed. As described above, when a fluoride is allowed to coexist, the self-repairing action caused by the fluoride becomes remarkable, and the corrosion inhibiting effect is improved.

  Patent Document 2 discloses a surface-treated zinc-based plated steel sheet having a coating (organic-inorganic composite coating) containing a metal compound of Mg, Mn, and Al, an acrylic resin, an organic acid, or the like on the surface of a zinc-based plating layer. It is disclosed. The organic-inorganic composite film is said to exhibit performance excellent in corrosion resistance after alkaline degreasing.

  Patent Document 3 discloses a first coating layer made of a metal compound of Mg, Mn, and Al on the surface of a zinc-based plating layer, and an organic resin layer made of an epoxy resin and a glycoluril resin on the first coating layer. A surface-treated galvanized steel sheet is disclosed, and it is shown that it has excellent solvent resistance as well as corrosion resistance.

  In addition to the corrosion resistance as described above, it has been studied to provide adhesion to an organic resin layer such as a top coat or an adhesive film. For example, in Patent Document 4, an inorganic compound layer containing Fe and Al or Zr is provided, and silane coupling is provided at the interface between the inorganic compound layer and the resin layer in order to ensure adhesion between the compound layer and the resin layer. A technique for forming an agent layer is disclosed.

Japanese Patent Laid-Open No. 2002-194558 JP 2002-294467 A Japanese Patent Laid-Open No. 2003-253457 JP 2005-344147 A

  As described above, various non-chromate films have been studied in galvanized steel sheets, and functions such as organic resin adhesion (secondary adhesion) have been attempted in addition to corrosion resistance. Among them, the inorganic coating has extremely high barrier properties and is excellent in durability and heat resistance as compared with the organic coating and the organic-inorganic composite coating. The present inventors have found that an inorganic film of metal oxide or metal hydroxide formed from a complex ion of fluorine ions and metal ions not using hexavalent chromium has excellent corrosion resistance (corrosion resistance) in galvanized steel sheets. I found out that However, when the galvanized steel sheet was processed, the problem that the corrosion resistance was not sufficient was revealed. In order to improve the corrosion resistance of the processed part, an attempt was further made to coat the organic resin layer, but the adhesion between the inorganic film and the organic resin layer was insufficient. In particular, when intense processing such as T-bending or Erichsen was performed, there was a problem that peeling of the organic resin layer was remarkable and the corrosion resistance of the processed part was not improved. As in Patent Document 4, when the silane coupling agent is used, the adhesion of the organic resin layer is improved to some extent, but there is a problem that it is not effective for the corrosion resistance of the strongly processed portion. Furthermore, an increase in the number of silane coupling agent treatment steps is not preferable in terms of production efficiency.

  The present invention has been made in view of the above problems, and is a galvanized steel sheet coated with an inorganic coating that does not use chromium, and further provided with an organic resin layer thereon, and particularly excellent in corrosion resistance of a processed part. Another object is to provide a surface-treated galvanized steel sheet.

  As a result of earnestly examining the means for solving the above problems, the present inventors have found that a galvanized steel sheet has a hydroxide or oxide of at least one element selected from the group consisting of Si, Ti, Zr, and Hf. In the film consisting of either or both, zinc atoms are contained in a solid solution state, and an organic resin layer composed of a crosslinkable organic resin matrix and an inorganic rust preventive agent is applied to the upper part of the film, so that the processed portion has excellent corrosion resistance. It was found that a zinc-based plated steel sheet can be obtained.

The gist of the present invention is as follows.
(1) A coating A made of an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V or a mixture of an oxide and a hydroxide on a zinc-based plated steel sheet; On the coating A, an organic resin layer B comprising 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent, and the remaining inorganic rust preventive agent. And the coating A further contains 13 to 50 atomic% of zinc atoms dissolved in the coating A with respect to all elements constituting the coating A. Plated steel sheet.
(2) At least one element selected from the group consisting of zinc oxide and / or zinc hydroxide film C on the zinc-based plated steel sheet, and Si, Ti, Zr, Hf, and V on the film C. A crosslinkable organic resin matrix formed by a reaction between a coating A composed of an oxide of the above or a mixture of an oxide and a hydroxide, and an aqueous resin having a carboxyl group and / or a hydroxyl group on the coating A and a crosslinking agent Zinc which has organic resin layer B which consists of 50-90 mass% and remainder inorganic rust preventive agent, and the above-mentioned film A is further dissolved in film A to all elements which constitute the above-mentioned film A A surface-treated galvanized steel sheet containing 13 to 50 atomic percent of atoms.
(3) Forming a coating A comprising an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of oxide and hydroxide on a zinc-based plated steel sheet,
After forming the film A, the film is subjected to anodization treatment and / or heat treatment at 200 to 400 ° C. in a vacuum, and zinc atoms in the film A are 13 to 50 atomic% with respect to all elements constituting the film A. Solubilize,
An organic resin layer B comprising 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent on the coating A, and the remaining inorganic rust preventive agent. A method for producing a surface-treated galvanized steel sheet, characterized in that
(4) Form a coating C made of zinc oxide and / or zinc hydroxide on a zinc-based plated steel sheet,
Forming on the coating C a coating A composed of an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of oxide and hydroxide,
After forming the film A, the film is subjected to anodization treatment and / or heat treatment at 200 to 400 ° C. in a vacuum, and zinc atoms in the film A are 13 to 50 atomic% with respect to all elements constituting the film A. Solubilize,
On the coating A, an organic resin layer B composed of 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent, and the remaining inorganic rust preventive agent is formed. A method for producing a surface-treated galvanized steel sheet characterized by comprising:

  ADVANTAGE OF THE INVENTION According to this invention, it is a film with a low environmental impact which does not use chromium, Comprising: The surface treatment zinc-based plated steel plate excellent in the process part corrosion resistance can be provided. Furthermore, since the surface-treated zinc-based plated steel sheet of the present invention is excellent in processed part corrosion resistance, it can be used in a wide range of applications from automobiles, home appliances, and building materials.

  The present invention is described in detail below.

  The surface-treated zinc-based plated steel sheet of the present invention is a zinc-based plated steel sheet, an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of an oxide and a hydroxide. 50% to 90% by mass of a crosslinkable organic resin matrix formed by a reaction of an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent on the film A, and the rest inorganic rust prevention An organic resin layer B made of an agent is applied, and the coating A further contains zinc atoms that are dissolved in a specific proportion of the coating A.

Corrosion resistance is improved in a zinc-plated steel sheet coated with a coating A and an organic resin layer B of an oxide or hydroxide of at least one element of Si, Ti, Zr, Hf, and V. However, as described above, when the present inventors investigated, after performing severe processing such as T-bending, in the processed portion, the coating A of oxide or hydroxide containing no zinc element and organic It was found that there was a problem that peeling occurred at the interface with the resin layer B and the corrosion resistance after processing deteriorated. Therefore, the present inventors include 13 to 50 atomic% of zinc atoms that are solid-solved in the film A with respect to all elements constituting the film A in the film A of the oxide or hydroxide. As a result, it was found that the adhesion between the film A and the resin layer B was improved, and a film without a peeling portion at the interface could be formed even after the processing. Thereby, it is possible to obtain a zinc-based plated steel sheet that is extremely excellent in the corrosion resistance of the processed part.

If the zinc atoms dissolved in the film A are less than 13 atomic% with respect to all elements constituting the film A, the number of zinc atoms that interact with the resin layer B is small. Adhesion cannot be ensured and sufficient processed portion corrosion resistance cannot be obtained. On the other hand, if it exceeds 50 atomic%, the adhesion with the organic resin layer B can be ensured, but the influence of the zinc atoms in the coating A as zinc oxide precipitates and expands in volume, which increases the coating structure. Since cracks occur in the film, as a result, sufficient corrosion resistance cannot be obtained . In here, the atomic%, illustrates a number of atoms of zinc atoms to the total number of atoms constituting the film A as a percentage. Therefore, it corresponds to mol% of zinc atoms in the coating A.

  When the oxide or hydroxide of at least one element of Si, Ti, Zr, Hf, and V constituting the coating A of the present invention is formed on a galvanized steel sheet, the corrosion resistance of the steel sheet is improved. This is because the oxides and hydroxides are not easily attacked by acids and alkalis, and work as a barrier film to create a network structure through metal and oxygen, protecting the steel sheet surface from corrosion factors such as water and oxygen. It is because the ability to do is high.

  When zinc atoms are contained in the oxide or hydroxide film A in a solid solution state, the adhesion with the organic resin layer B as described above, particularly the adhesion after the strong processing is improved, As a result, although the detailed reason why the processed portion corrosion resistance is improved is unknown, the zinc atom contained in the coating A and the carboxyl group or hydroxyl group in the organic resin layer interact attractively, and the coating A and It is expected that the adhesion with the resin layer B is improved.

  Elements other than zinc atoms that interact with carboxyl groups and hydroxyl groups are expected to exist (for example, aluminum). However, other than zinc atoms, the inclusion in the film increases the cost. . In order to contain zinc atoms in the film A, for example, anodization treatment may be used to diffuse zinc atoms from the plating layer to the film side, which is advantageous in that the cost can be kept low.

  The film A of the present invention is formed from at least one oxide selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of oxide and hydroxide. Note that the coating A does not contain Cr. Therefore, the non-chromated steel sheet is preferable from the viewpoint of environmental load.

  In the film A, zinc atoms are dissolved in the film. When zinc atoms exist as a compound, the compound needs to be in contact with the resin layer. In this case, although an attractive interaction between the compound and the resin layer is expected, the zinc-based plated steel sheet is processed. When this is done, there is a concern that the resin layer may peel off starting from the compound, which is not preferable.

  The zinc atoms dissolved in the coating A are defined by observing the cross-sectional structure of the coating with a transmission electron microscope, and the state in which the zinc atoms are not precipitated as metallic zinc or a compound is defined as solid solution. In addition, the zinc atom dissolved in the coating A is determined by observing the cross-sectional structure of the coating A with a transmission electron microscope, analyzing the observation site with energy dispersive X-ray spectroscopy, and determining the zinc concentration. Just do it.

  The thickness of the coating A is preferably 0.005 to 0.5 μm. When the thickness is less than 0.005 μm, sufficient corrosion resistance is not imparted to the steel sheet. When the thickness exceeds 0.5 μm, defects such as cracks are introduced during film formation, and corrosion resistance is expected to deteriorate. More preferably, it is 0.01-0.2 micrometer.

In order to produce the coating A, a treatment liquid containing one or more of phosphates, carbonates, nitrates, hydroxides, fluorides, and complex fluorides of Si, Ti, Zr, Hf, and V It is preferably formed from (made aqueous solution). Further, the treatment liquid may contain one or more fluorine-containing compounds such as HF, HBF ₄ , NaHF ₂ , KHF ₂ , NH ₄ HF ₂ , NaF, KF, NH ₄ F, etc. Good.

  A method for forming the coating A on the zinc-based plated steel sheet using the above treatment liquid will be described. In the treatment liquid, a chemical equilibrium reaction represented by the following formula (I) or (II) is established.

M (An) _{4 / m} + 2H ₂ O ⇔ MO ₂ + 4H ⁺ + (An) _{4 / m} (I)
^{_{MF 6 2- + 2H 2 O ⇔}} MO 2 + 4H + + 6F - ··· (II)
(M: at least one metal element selected from the group consisting of Si, Ti, Zr, Hf and V
An: Phosphate ion, carbonate ion, nitrate ion, hydroxyl group
m: An valence)
Here, by adding a driving agent for advancing the equilibrium reaction of the formula (I) or (II) to the right side, MO ₂ is precipitated and a film is formed on the plating surface. As a driving agent for promoting film formation, for example, zinc ions eluted from a zinc-based plated steel sheet can be used. Thereby, the film A made of a mixture of an oxide and a hydroxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V is obtained.

  The pH of the treatment liquid is preferably 2-7, more preferably 3-4. The reason is that when the treatment solution pH is less than 2, the plated steel sheet (base material) is severely corroded and it is difficult to obtain a sound coating. When the treatment solution pH is greater than 7, the solution becomes unstable. This is because there is a problem that agglomerated in the treatment liquid is deposited and it is difficult to form a uniform film on the surface of the substrate. The treatment solution pH may be adjusted by a well-known method, and other conditions for the precipitation reaction of the present invention are not particularly limited. In addition, since the film formation rate increases with an increase in the temperature of the treatment liquid, the reaction temperature and the reaction time may be set in a timely manner in order to coat the film A with a desired thickness.

  When the film A composed of a mixture of the above oxide and hydroxide is heat-treated in a vacuum, it tends to be a film composed of a highly crystalline oxide. The heat treatment temperature is preferably in the range of 300 to 450 ° C.

In the present invention, the zinc in the coating A is included to some extent by the elution from the zinc plating when the coating A is formed on the zinc-based plated steel plate. after forming the film a, the substrate was anodized by diffusing the zinc atoms in the coating a, or, after the anodic oxidation treatment, a heat treatment at facilities Succoth at 200 to 450 ° C. in vacuo, The coating A contains 13 to 50 atomic% of zinc atoms that are dissolved in the coating A with respect to all elements constituting the coating A. In order to increase the zinc atom concentration at the interface, zinc atoms may be diffused in advance on the surface side of the coating A by using an anodic oxidation process described later.

  Another surface-treated zinc-based plated steel sheet of the present invention includes a coating C made of zinc oxide and / or zinc hydroxide on a zinc-based plated steel sheet, and Si, Ti, Zr, Hf, A coating A comprising an oxide of at least one element selected from the group consisting of V, or a mixture of an oxide and a hydroxide, and an aqueous resin having a carboxyl group and / or a hydroxyl group on the coating A; The organic resin layer B which consists of 50-90 mass% of the crosslinkable organic resin matrix formed by reaction with a crosslinking agent and the remainder inorganic rust preventive agent is given.

  Here, the film C is a film made of zinc oxide and / or zinc hydroxide, and the film C may be a film made only of zinc oxide, and may further contain a hydroxide of zinc.

  Further, the film C may contain 0.1 to 5 atomic percent of hydrogen and 0.1 to 5 atomic percent of fluorine atoms as impurities.

  The film C is formed when the anodizing treatment is applied to the zinc-based plated steel sheet in order to increase the concentration of zinc atoms contained in the film A. In this case, it is preferable that the film C is formed because the adhesion between the film A and the resin layer B is further improved.

  The coating C made of zinc oxide and / or zinc hydroxide is formed during the anodizing treatment performed when more zinc atoms are contained in the coating A, thereby improving the corrosion resistance of the steel sheet. I can do it. As a method for forming zinc oxide on a zinc-based plated steel sheet, the base material may be anodized after the coating A is formed on the base material. The conditions for anodization may be those conventionally used as is known, for example, in JP-A-7-289913.

  The film C made of a mixture of the above oxide and hydroxide also tends to become a film made of a highly crystalline oxide when heat-treated in a vacuum. The heat treatment temperature is preferably in the range of 300 to 450 ° C.

  The organic resin layer B is composed of 50 to 90% by mass of a crosslinkable organic resin formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent, and the remaining inorganic rust inhibitor. The crosslinkable organic resin is a matrix of the organic resin layer B. The crosslinkable organic resin is formed by a reaction between an aqueous resin and a crosslinking agent. The reason for including a crosslinkable organic resin is to impart corrosion resistance and solvent resistance to the steel sheet. In order to ensure the solvent resistance, it is generally necessary to select a resin having a large difference from the solubility parameter (SP) of the solvent used. However, in order to deal with a wide range from kerosene having a low SP to ethanol having a high SP, it is more effective to insolubilize by crosslinking than SP. In order to suppress the solubility of the resin coating alone in the solvent, the higher the degree of cross-linking of the resin, the more effective, but the adhesion between the base material and the top coating tends to decrease as the degree of cross-linking increases. The reason why the adhesiveness decreases when the degree of cross-linking is high is presumed to be because strain and polar functional groups generated by the cross-linking reaction are used in the cross-linking reaction and disappear.

  The aqueous resin includes a water-soluble resin and a resin (water-dispersible resin) that is essentially water-insoluble but can be finely dispersed in water, such as an emulsion or suspension.

  The aqueous resin is not particularly limited, but is preferably at least one selected from the group consisting of an aqueous polyester resin, an aqueous polyurethane resin, an aqueous epoxy resin, an aqueous acrylic resin, an aqueous polyolefin resin, and an aqueous phenol resin.

  The aqueous polyester resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylol ethane, trimethylol propane. Dehydration condensation of polyhydric alcohols such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, sebacic acid, maleic anhydride, itaconic acid, fumaric acid, and hymic anhydride It can be obtained by neutralizing with ammonia, organic amine or the like and dispersing in water.

  The aqueous polyurethane resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylol ethane, trimethylol propane. Polyhydric alcohols such as hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and the like, and chain extension with diamine etc. and water dispersion to obtain I can do it.

  The water-based epoxy resin is not particularly limited. For example, an epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, resorcinol type epoxy resin, phenol / novolak type epoxy resin is forcibly emulsified with a surfactant, It can be obtained by a method obtained by dispersing or by reacting the above epoxy resin with a high acid value acrylic resin, followed by neutralization with ammonia, an organic amine or the like and water dispersion.

  The aqueous acrylic resin is not particularly limited, and examples thereof include unsaturated monomers such as styrene, alkyl (meth) acrylates, (meth) acrylic acid, hydroxyalkyl (meth) acrylates, and alkoxysilane (meth) acrylates. Can be obtained by radical polymerization in an aqueous solution using a polymerization initiator. The polymerization initiator is not particularly limited, and for example, persulfates such as potassium persulfate and ammonium persulfate, azo compounds such as azobiscyanovaleric salt and azobisisobutyronitrile can be used.

  The aqueous polyolefin resin is not particularly limited. For example, after radical polymerization of ethylene and an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid under high temperature and high pressure, ammonia And amine compounds, metal compounds such as KOH, NaOH, LiOH, or those obtained by neutralization with ammonia or amine compounds containing the above metal compounds and dispersing in water.

  The aqueous phenol resin is not particularly limited, for example, a methynolized phenol resin obtained by addition reaction of aromatics such as phenol, resorcin, cresol, bisphenol A, paraxylylene dimethyl ether and formaldehyde in the presence of a reaction catalyst. And the like obtained by reacting the phenol resin with amine compounds such as diethanolamine and N-methylethanolamine and neutralizing with an organic acid or inorganic acid.

  The crosslinking agent is not particularly limited as long as it has a plurality of reactive functional groups, but is not limited to amino resins, polyisocyanate compounds, block compounds thereof (block compounds of the above polyisocyanate compounds), epoxy compounds, carbodiimide compounds, silane cups. It is preferably at least one selected from the group consisting of a ring agent, a crosslinkable zirconium compound and a crosslinkable titanium compound. These may be used alone or in combination of two or more.

  It does not specifically limit as said amino resin, For example, a melanin resin, a benzoguanamine resin, a urea resin, a glycoluril resin etc. can be mentioned.

  It does not specifically limit as said polyisocyanate compound, For example, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate etc. can be mentioned.

  The epoxy compound is not particularly limited as long as it is a compound having a plurality of oxirane rings. For example, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, sorbitan polyglycidyl ether, pentaerythritol polyglycidyl ether Glycerin polyglycidyl ether, trimethylpropane polyglycidyl ether, neopentyl glycol polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol glycol diglycidyl ether, polypropylene glycol glycol diglycidyl ether, 2, 2-bis -(4'-glycidyloxyphenyl) propane, tris (2,3-epoxypropyl) isocyanurate DOO, bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether and the like.

  As the carbodiimide compound, for example, after synthesizing an isocyanate-terminated polycarbodiimide by a condensation reaction involving decarbonization of a diisocyanate compound such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate, the reactivity with an isocyanate group is further increased. Examples thereof include a compound to which a hydrophilic segment having a functional group is added.

  The silane coupling agent is not particularly limited. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane sold by Shin-Etsu Chemical, Nippon Unicar, Chisso, Toshiba Silicone, etc. γ-aminopropylethoxysilane, N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxy Propylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2- (3 , 4- Poxycyclohexyl) ethyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ -Aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like can be mentioned. The said silane coupling agent may be used independently and may use 2 or more types together.

  The crosslinkable zirconium compound is not particularly limited as long as it is a zirconium-containing compound having a plurality of functional groups capable of reacting with a carboxyl group or a hydroxyl group, but is preferably a compound that is soluble in water or an organic solvent. More preferably, it is a zirconium compound. An example of such a compound is ammonium zirconium carbonate.

  The crosslinkable titanium compound is not particularly limited as long as it is a titanium-containing compound having a plurality of functional groups capable of reacting with a carboxyl group or a hydroxyl group, but dipropoxy bis (triethanolaminato) titanium, dipropoxy bis (diethanolaminato). ) Titanium, propoxy tris (diethanolaminato) titanium, dibutoxy bis (triethanolaminato) titanium, dibutoxy bis (diethanolaminato) titanium, dipropoxy bis (acetylacetonato) titanium, dibutoxy bis (acetylacetonato) Titanium, dihydroxy bis (lactato) titanium monoammonium salt, dihydroxy bis (lactato) titanium diammonium salt, propanedioxytitanium bis (ethylacetoacetate), oxotitanium bis (monoammo) Um oxalate), isopropyl tri (N- amidoethyl-aminoethyl) titanate and the like. The said crosslinking agent may be used independently and may use 2 or more types together.

  The combination of the aqueous resin and the crosslinking agent may be a conventionally known condition described in, for example, JP-A-2005-281863.

  In the organic resin layer B, the content of the crosslinkable organic resin is 50 to 90% by mass in 100% by mass of the coating. If it is less than 50% by mass, the adhesion to the coating A or the top coating may be lowered. If it exceeds 90% by mass, the corrosion resistance may decrease.

  The resin layer B contains an inorganic rust preventive agent, and thereby further excellent corrosion resistance can be obtained.

  While the coating A and the organic resin layer B exhibit an excellent barrier effect against corrosion factors, they do not have a self-healing function, so that when the coating is damaged, the zinc elution reaction proceeds. The inorganic rust preventive agent is dispersed in the resin layer B, and has a function of suppressing elution of the galvanized layer by forming a precipitate film at the film damage site or by elution from the resin layer.

  In the resin layer B coating, the content of the inorganic rust inhibitor as the remaining component is 10% by mass for the lower limit and 50% by mass for the upper limit in 100% by mass of the coating. If the content of the inorganic rust preventive agent is less than 10% by mass, the corrosion resistance may be reduced, and if it exceeds 50% by mass, the adhesion with the coating A and the top coat may be reduced. More preferably, it is 15-40 mass%.

  The resin layer B contains an inorganic rust preventive agent, whereby excellent corrosion resistance can be obtained. The inorganic rust inhibitor is not particularly limited, and a conventionally known inorganic rust inhibitor can be used. From the group consisting of silica particles, titania particles, alumina particles, zirconia particles, phosphate compounds, niobium compounds. It is preferable that at least one selected. The silica particles, titania particles, alumina particles, and zirconia particles preferably have an average particle diameter of about 1 to 300 nm. These may be used alone or in combination of two or more.

  Examples of the phosphoric acid compound include phosphoric acids such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and salts thereof; aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1, 1- Examples thereof include phosphonic acids such as diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid) and salts thereof; organic phosphoric acids such as phytic acid and salts thereof. The cation species of the salt is not particularly limited, and examples thereof include Cu, Co, Fe, Mn, Sn, V, Mg, Ba, Al, Ca, Sr, Nb, Y, Ni, and Zn. These may be used alone or in combination of two or more.

  The niobium compound is not particularly limited, and a conventionally known niobium-containing compound can be used, and examples thereof include niobium oxide, niobic acid and its salt, fluoroniobate, and fluorooxoniobate. Among these, niobium oxide is preferable from the viewpoint of improving corrosion resistance.

  The niobium compound is more preferably niobium oxide colloidal particles. Thereby, corrosion resistance can be improved. A coating can be formed by applying an aqueous coating containing niobium oxide colloidal particles dispersed in an aqueous medium to a metal plate. The niobium oxide colloidal particles have a smaller average particle diameter, and a more stable and dense coating containing niobium oxide is formed. More preferable.

  The niobium oxide colloidal particles in the aqueous coating are those in which niobium oxide is dispersed in water in the form of fine particles. For example, niobium oxide is not formed strictly, and it is an intermediate state between niobium hydroxide and niobium oxide. It may be in an amorphous state.

  The niobium oxide colloidal particles preferably have an average particle size of 1000 nm or less. The average particle diameter is more preferably 2 to 600 nm, and further preferably 2 to 100 nm. A smaller average particle diameter is more preferable because a coating film containing niobium oxide that is more stable and dense can be formed.

  Further, in the resin layer B, if necessary, in order to further improve the corrosion resistance and to give other performances such as slidability and scratch resistance, an organic rust preventive agent, wax Various additives usually used for other surface treatment agents may be contained.

The coating amount of the resin layer B is preferably 0.1 g / m ² or more as a dry coating. If it is less than 0.1 g / m ² , the corrosion resistance and alkali resistance may decrease. On the other hand, if the amount of the coating is too large, the cost is increased, the conductivity is deteriorated, and the welding workability is lowered. More preferably, it is 0.1 to 5 g / m ² , and more preferably 0.5 to 2 g / m ² .

  The resin layer B is a layer formed on the coating A, and is a coating layer made of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin and a crosslinking agent, and an inorganic rust inhibitor. .

  The crosslinkable organic resin matrix is formed by a reaction between an aqueous resin and a crosslinking agent, but the crosslinking reaction may be performed when the coating is formed on the coating A of the galvanized steel sheet. Alternatively, a part of the reaction may be performed before the film is formed, and the reaction may be completed when the film is formed.

  The coating method of the aqueous composition used for the formation of the resin layer is to apply the aqueous composition to the surface of the galvanized steel sheet to form a film. As used herein, the aqueous composition is used to form a film comprising components such as the crosslinked resin matrix, the inorganic rust inhibitor, and, if necessary, an organic rust inhibitor and a lubricant. It suffices if the components are blended, and the order of addition is not particularly limited. The coating method of the aqueous composition is not particularly limited, and commonly used roll coat, air spray, airless spray, immersion and the like can be employed as appropriate. In order to improve the curability of the film, it is preferable to heat the object to be coated in advance or to heat-dry the object after coating. As the thermal drying method, any method such as hot air, induction heating, near infrared, far infrared, etc. may be used, or they may be used in combination. The heating temperature of the article to be coated is 50 to 250 ° C, preferably 70 to 220 ° C. When the heating temperature is less than 50 ° C., the evaporation rate of water is slow and sufficient film formability cannot be obtained, so that the corrosion resistance may be lowered. On the other hand, when the temperature exceeds 250 ° C., the resin is thermally decomposed to deteriorate the corrosion resistance, and the appearance such as yellowing may be deteriorated. The drying time for heat drying after coating is preferably 1 second to 5 minutes. Moreover, if resin is hardened | cured with an electron beam or an ultraviolet-ray, hardening by these irradiation may be sufficient, and combined use with heat drying may be sufficient.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, there is a missing number in the experiment number.

  As described below, after the coating A was formed using various treatment liquids, the resin layer B was applied, and then the processed portion corrosion resistance was evaluated.

  A zinc-based plated steel sheet produced by electrogalvanizing (EG) was prepared, and a coating A was formed thereon using a treatment liquid having a composition shown in Tables 1 to 5. “Zinc concentration in coating A” in Tables 1 to 5 indicates the atomic percentage of zinc atoms dissolved in coating A.

  Moreover, about the case where the coating C which consists of a zinc oxide and / or zinc hydroxide is formed on a zinc-based plated steel plate, after forming the coating A, anodizing treatment and heat treatment are performed under the conditions described in Tables 1 to 5. gave. In Tables 1 to 5, in the column “Aspect of coating C”, the mixture represents a mixture of zinc oxide and zinc hydroxide, and the oxide represents zinc oxide.

Next, an aqueous composition containing the aqueous resin shown in Table 6 was applied to the steel sheet on which the coating A was formed with a bar coater so as to have a dry adhesion amount of 1.5 g / m ² , and an ultimate plate temperature of 150 ° C. in a hot air drying furnace. After drying, the sample was cooled with water to obtain a test material. In Tables 1 to 5, “film A / resin layer B” indicates a cross-sectional structure from the substrate side to the film side.

The processed part corrosion resistance test was performed by extruding 6 mm with an elixir tester, and then tape-sealing the edges and back of the test plate, and conducting a salt spray test (JIS-Z-2371). The occurrence of white rust was observed after 120 hours of test time on the part subjected to Erichsen processing and evaluated as follows.
A: No occurrence of white rust B: Less than 10% B: Less than 20% X: 20% or more The presence or absence of a peeling portion at the interface between the coating A and the resin layer B, the mode of the coating, and the cross-sectional structure are measured by a transmission electron microscope Examined. Further, the zinc atom concentration in the coating A was examined by an energy dispersive X-ray spectrometer attached to the transmission electron microscope.

[Experiment Nos. 6-9, 11-15 ]
The treatment solution was 0.1M ammonium hexafluorotitanate aqueous solution, and the pH was adjusted to 3,4,5,6,7 with hydrofluoric acid or ammonia water. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 26]
The treatment solution was 0.1M ammonium hexafluorozirconate aqueous solution, and the pH was adjusted to 3,4,5,6,7 with hydrofluoric acid or ammonia water. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 41 ]
The treatment solution was 0.1M ammonium hexafluorosilicate aqueous solution, and the pH was adjusted to 3,4,5,6,7 with hydrofluoric acid or ammonia water. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours .
[Experiment No 71-73 ]
The treatment solution was 0.005M vanadyl nitrate aqueous solution, and the pH was adjusted to 3,4,5,6,7 with hydrofluoric acid or ammonia water. The film formation was performed by immersing the base material in the treatment liquid at room temperature and then performing electrolysis. The electrolysis was carried out for 5 seconds while controlling the current density at 50 mA / cm ² in the treatment solution. After film formation, it was washed with water and air dried. Some of the substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 76-93]
The treatment solution was 0.1M ammonium hexafluorotitanate aqueous solution, and the pH was adjusted to 5.5 with aqueous ammonia. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Thereafter, the substrate was an anode, the stainless steel plate was a cathode, and an anodization was applied in an electrolytic solution by applying a DC voltage of 20 to 190 mV for 10 minutes. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 100 ~111]
The treatment solution was 0.1M ammonium hexafluorozirconate aqueous solution, and the pH was adjusted to 5.5 with aqueous ammonia. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Thereafter, the substrate was an anode, the stainless steel plate was a cathode, and an anodization was applied in an electrolytic solution by applying a DC voltage of 20 to 190 mV for 10 minutes. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 118 ~129]
The treatment solution was 0.1M ammonium hexafluorosilicate aqueous solution, and the pH was adjusted to 5.5 with aqueous ammonia. Film formation was performed by immersing the substrate in the treatment solution at room temperature for 5 minutes, and after the film formation, washed with water and air-dried. Thereafter, the substrate was an anode, the stainless steel plate was a cathode, and an anodization was applied in an electrolytic solution by applying a DC voltage of 20 to 190 mV for 10 minutes. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 136 to 147]
The treatment solution was an aqueous solution in which hafnium (IV) oxide was dissolved in hydrofluoric acid, and the pH was adjusted to 3,4,5,6,7 with aqueous ammonia. The film formation was performed by immersing the base material in the treatment liquid at room temperature and then performing electrolysis. The electrolysis was carried out for 5 seconds while controlling the current density at 50 mA / cm 2 in the treatment solution. After film formation, it was washed with water and air dried. Thereafter, the substrate was an anode, the stainless steel plate was a cathode, and an anodization was applied in an electrolytic solution by applying a DC voltage of 20 to 190 mV for 10 minutes. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No 152 -165]
The treatment solution was 0.005M vanadyl nitrate aqueous solution, and the pH was adjusted to 3,4,5,6,7 with aqueous ammonia. The film formation was performed by immersing the base material in the treatment liquid at room temperature and then performing electrolysis. The electrolysis was carried out for 5 seconds while controlling the current density at 50 mA / cm ² in the treatment solution. After film formation, it was washed with water and air dried. Thereafter, the substrate was an anode, the stainless steel plate was a cathode, and an anodization was applied in an electrolytic solution by applying a DC voltage of 20 to 190 mV for 10 minutes. Some substrates were subsequently heat-treated in vacuum at 200 ° C. and 400 ° C. for 3 hours.
[Experiment No. 166-168]
The treatment solution was 0.1M ammonium hexafluorotitanate aqueous solution, and the pH was adjusted to 5.5 with aqueous ammonia. Film formation was performed by short-circuiting the base material and the aluminum plate at room temperature and immersing in a treatment solution for 1 minute. After film formation, the film was washed with water and air-dried.

Claims (4)

On a zinc-plated steel sheet, a coating A comprising an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of oxide and hydroxide;
Further, an organic resin layer comprising 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent on the coating A, and the remaining inorganic rust inhibitor. B
The coating A further contains 13 to 50 atomic% of zinc atoms dissolved in the coating A with respect to all elements constituting the coating A. . A coating C made of zinc oxide and / or zinc hydroxide on a zinc-based plated steel sheet,
Furthermore, a coating A comprising an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V or a mixture of oxide and hydroxide on the coating C;
Further, on the coating A, an organic resin layer B comprising 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent, and the remaining inorganic rust preventive agent. Have
The coating A further contains 13 to 50 atomic% of zinc atoms dissolved in the coating A with respect to all elements constituting the coating A. . On the zinc-based plated steel sheet, a film A composed of an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V or a mixture of oxide and hydroxide is formed.
  After forming the film A, the film is subjected to anodization treatment and / or heat treatment at 200 to 400 ° C. in a vacuum, and zinc atoms in the film A are 13 to 50 atomic% with respect to all elements constituting the film A. Solubilize,
  An organic resin layer B comprising 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent on the coating A, and the remaining inorganic rust preventive agent. A method for producing a surface-treated galvanized steel sheet, characterized in that Form a coating C made of zinc oxide and / or zinc hydroxide on a zinc-based plated steel sheet,
  Forming on the coating C a coating A composed of an oxide of at least one element selected from the group consisting of Si, Ti, Zr, Hf, and V, or a mixture of oxide and hydroxide,
  After forming the film A, the film is subjected to anodization treatment and / or heat treatment at 200 to 400 ° C. in a vacuum, and zinc atoms in the film A are 13 to 50 atomic% with respect to all elements constituting the film A. Solubilize,
  On the coating A, an organic resin layer B composed of 50 to 90% by mass of a crosslinkable organic resin matrix formed by a reaction between an aqueous resin having a carboxyl group and / or a hydroxyl group and a crosslinking agent, and the remaining inorganic rust preventive agent is formed. A method for producing a surface-treated galvanized steel sheet characterized by comprising: