WO2016152119A1 - Coated galvanized steel sheet - Google Patents

Coated galvanized steel sheet Download PDF

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Publication number
WO2016152119A1
WO2016152119A1 PCT/JP2016/001559 JP2016001559W WO2016152119A1 WO 2016152119 A1 WO2016152119 A1 WO 2016152119A1 JP 2016001559 W JP2016001559 W JP 2016001559W WO 2016152119 A1 WO2016152119 A1 WO 2016152119A1
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WO
WIPO (PCT)
Prior art keywords
steel sheet
compound
mass
coating film
chemical conversion
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PCT/JP2016/001559
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French (fr)
Japanese (ja)
Inventor
俊之 大熊
智文 重國
佑介 大澤
古田　彰彦
Original Assignee
Ｊｆｅ鋼板株式会社
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Publication of WO2016152119A1 publication Critical patent/WO2016152119A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C09D175/06—Polyurethanes from polyesters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • 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
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • 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
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • 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
    • C23C22/60—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 alkaline aqueous solutions with pH greater than 8
    • 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
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • 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
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon

Definitions

  • the present invention relates to a chromate-free coated galvanized steel sheet excellent in corrosion resistance, in particular, corrosion resistance in a processed part such as a bend and a cut end face.
  • Zinc or zinc-containing alloy coated steel sheet (hereinafter abbreviated as “zinc-based plated steel sheet”) is formed with a chemical conversion coating and a primer coating on which various coatings are formed.
  • Plated steel sheet has many advantages such as stability of quality and rationalization by omitting the painting process by customers. Therefore, exterior materials such as roofs and walls of buildings, interior materials such as partitions, and each component of electrical equipment products Widely used as, etc.
  • coated galvanized steel sheets are subjected to various processing including 90-degree bending or 180-degree bending by press forming, roll forming, or embossing, and have long-term coating durability performance after use. Required.
  • a zinc-plated steel sheet is subjected to a chemical conversion treatment containing chromate, a chromate-based anticorrosive pigment is incorporated into the primer coating, and a thermosetting polyester resin as a top coat on top.
  • a coated zinc-based plated steel sheet on which a fluororesin coating film is formed is applied to a coating film or a request having higher weather resistance.
  • Patent documents 1 to 4 have been proposed as technologies corresponding to these needs.
  • Patent Document 1 describes a coated galvanized steel sheet obtained by coating a galvanized steel sheet with a coating composition containing a non-chromate rust preventive pigment such as a molybdenum compound for forming a primer coating film via a chemical conversion coating. ing.
  • the applied galvanized steel sheet is limited to those containing 94% or more of zinc, and since chromate is applied as the chemical conversion coating, it cannot be said to be a chromate-free coated galvanized steel sheet. It was.
  • Patent Document 2 relates to a base treatment agent (chemical conversion treatment film) comprising a resin and a chromate-free rust preventive pigment.
  • Patent Document 2 is a technique for primary rust prevention without coating, and sufficient corrosion resistance cannot be obtained when applied as a chemical conversion treatment film of a coated galvanized steel sheet.
  • Patent Document 3 relates to a coated galvanized steel sheet using a base treatment agent (chemical conversion coating) composed of a resin and a chromate-free rust preventive pigment. Patent Document 3 proposes a total rust prevention design including a primer, but it cannot be said that the corrosion resistance of a processed part is particularly sufficient.
  • a base treatment agent chemical conversion coating
  • Patent Document 3 proposes a total rust prevention design including a primer, but it cannot be said that the corrosion resistance of a processed part is particularly sufficient.
  • Patent Document 4 is a coated zinc-plated steel sheet on which a specific chemical conversion treatment film containing a non-chromate anti-corrosion pigment and a primer film are formed, and a technique aimed at improving the total anti-rust property is described. ing. However, a sufficient effect cannot be obtained particularly on the corrosion resistance of the processed part.
  • the conventional chromate-free coated zinc-based plated steel sheet is inferior in corrosion resistance to the coated zinc-based plated steel sheet containing chromate, or the primer coating thickness is higher than that of the coated zinc-based plated steel sheet containing chromate. It was necessary to remarkably increase the thickness, which was inferior in economic efficiency.
  • the present invention has an object to provide a chromate-free coated zinc-based plated steel sheet that is excellent in corrosion resistance, in particular, corrosion resistance in a processed part such as a bend and a cut end surface.
  • the present inventors have found that the above problems can be solved by forming a chemical conversion treatment film and a primer coating film containing specific common elements as shown below, and have reached the present invention. That is, the gist configuration of the present invention is as follows.
  • the chemical conversion film is a composite of a resin component and an inorganic component, and as the resin component, an anionic urethane resin (a) having an ester bond and an epoxy resin (b) having a bisphenol skeleton in total 30 to 50% by mass And the blending ratio of (a) and (b) is in the range of 3:97 to 60:40 by mass%, and the inorganic component is 2 to 10 mass% of vanadium compound and zirconium compound.
  • the primer coating film contains a polyester resin having a urethane bond as a main component, contains a vanadium compound, a phosphoric acid compound, and magnesium oxide, and the elongation at break at 25 ° C. of the primer coating film is 20% or more, and 25 A coated galvanized steel sheet having a tensile strength at 20 ° C. of 20 MPa or more.
  • the polyester resin is 40 to 88% by mass
  • the vanadium compound is 4 to 20% by mass
  • the phosphoric acid compound is 4 to 20% by mass
  • the magnesium oxide is 4 to 20% by mass.
  • the coated galvanized steel sheet of the present invention is excellent in corrosion resistance particularly in the processed part such as bending and the cut end face while being chromate-free which is advantageous in terms of environmental safety. Therefore, when the coated galvanized steel sheet of the present invention is applied to the building material field, long-term corrosion can be suppressed at the bent part of the roof molded product, the embossed part of the wall material, and the corner span bent part. Maintenance costs such as repairs can be greatly reduced.
  • a coated galvanized steel sheet includes a galvanized steel sheet, a chemical conversion film that does not contain a chromate compound formed on at least one surface of the galvanized steel sheet, and the chemical conversion film.
  • the zinc-based plated steel sheet used as a base is not particularly limited as long as it is a steel sheet containing zinc in the plating layer, but is not limited, but a hot-dip galvanized steel sheet (GI) or an alloyed alloy thereof.
  • Galvanized steel sheet such as hot dip galvanized steel sheet (GA), electrogalvanized steel sheet (EG), Zn—Ni plated steel sheet, Zn—Al plated steel sheet (eg, Zn-5 mass% Al alloy plated steel sheet, Zn-55 mass%) Al alloy-plated steel sheet), Zn—Al—Mg-plated steel sheet, and the like can be used.
  • the zinc plating layer contains one or more kinds of nickel, cobalt, manganese, iron, molybdenum, tungsten, titanium, chromium, aluminum, magnesium, lead, antimony, tin, copper as a small amount of different metal elements or impurities May be. Also, two or more of the same or different galvanized layers may be plated.
  • the chemical conversion coating is a composite of a resin component and an inorganic component, which contains an anionic urethane resin (a) having an ester bond as an resin component and an epoxy resin (b) having a bisphenol skeleton, and a vanadium compound as an inorganic component. , A zirconium compound, and a fluorine compound.
  • anionic urethane resin (a) having an ester bond a resin obtained by reacting a polyester polyol with diisocyanate or polyisocyanate having two or more isocyanate groups and copolymerizing dimethylol alkyl acid can be applied.
  • a chemical conversion treatment liquid can be obtained by dispersing in a liquid such as water by a known method.
  • Polyester polyols include polyesters obtained by dehydration condensation reaction from glycol components and acid components such as ester-forming derivatives of hydroxylcarboxylic acid, polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ⁇ -caprolactone, and the like. Copolyester is mentioned.
  • the polyisocyanate include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.
  • aromatic polyisocyanate examples include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-xylene diisocyanate, diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, and triphenyl.
  • Methane triisocyanate, polymethylene polyphenyl polyisocyanate, naphthalene diisocyanate, and derivatives thereof for example, prepolymers obtained by reaction with polyols, modified polyisocyanates such as carbodiimide compounds of diphenylmethane diisocyanate, etc.
  • Specific examples include a mixture obtained by carbodiimidizing a part of diphenylmethane diisocyanate.
  • dimethylol alkyl acid is copolymerized, self-emulsified and water-solubilized (water-dispersed), and ester bonds used in the present invention
  • epoxy resin (b) having a bisphenol skeleton a known resin can be used, and a chemical conversion treatment liquid can be obtained by dispersing in a liquid such as water by a known method.
  • the resin component acts as a binder for the chemical conversion coating, and the anionic urethane resin (a) having an ester bond is flexible so that the chemical conversion coating is less likely to break (peel) when processed.
  • the epoxy resin (b) has an effect of improving adhesion to the underlying zinc-based plated steel sheet and the upper primer coating film.
  • a total of 30 to 50% by mass of the resin component is included in the chemical conversion film. When the amount is less than 30% by mass, the binder effect of the chemical conversion film is lowered. When the amount exceeds 50% by mass, the function by the inorganic component described below, for example, the inhibitor action is lowered.
  • the compounding ratio of the anionic urethane resin (a) having an ester bond and the epoxy resin (b) having a bisphenol skeleton is within a range of 3:97 to 60:40 in terms of mass% when the total resin is 100. Outside this range, the adhesiveness decreases as the flexibility of the chemical conversion coating decreases.
  • the vanadium compound acts as a rust inhibitor (inhibitor) when added to the chemical conversion solution.
  • vanadium compounds include vanadium pentoxide, metavanadate, ammonium metavanadate, vanadium oxytrichloride, vanadium trioxide, vanadium dioxide, magnesium vanadate, vanadyl acetylacetonate, vanadium acetylacetonate, and the like.
  • a tetravalent vanadium compound or a tetravalent vanadium compound obtained by reduction or oxidation is desirable.
  • the content of the vanadium compound in the chemical conversion film is preferably 2 to 10% by mass. If the amount is less than 2% by mass, the inhibitor effect is reduced, resulting in a decrease in corrosion resistance. If the amount exceeds 10% by mass, the moisture resistance of the chemical conversion film is decreased.
  • Zirconium compounds are added to the chemical conversion treatment liquid, and can be expected to improve the strength and corrosion resistance of the chemical conversion treatment film due to the reaction with the plating metal and the coexistence with the resin component. Furthermore, the zirconium compound itself is a dense chemical conversion treatment film. The barrier effect can be expected from the fact that it contributes to the formation of the film and is rich in coverage. Examples of the zirconium compound include neutralized salts such as zirconium sulfate, zirconium carbonate, zirconium nitrate, zirconium lactate, zirconium acetate, and zirconium chloride.
  • the content of the zirconium compound in the chemical conversion film is preferably 40 to 60% by mass. If it is less than 40% by mass, the strength and corrosion resistance of the chemical conversion coating will be reduced, and if it exceeds 60% by mass, the chemical conversion coating will become brittle and the chemical conversion coating will be destroyed or peeled off when subjected to severe processing. is there.
  • Fluorine compound is added to the chemical conversion treatment liquid and acts as an adhesiveness imparting agent with the galvanized steel sheet.
  • a fluoride salt such as ammonium salt, sodium salt, or potassium salt
  • a fluorine compound such as ferrous fluoride or ferric fluoride
  • ammonium fluoride and fluoride salts such as sodium fluoride and potassium fluoride are desirable.
  • the content of the fluorine compound in the chemical conversion film is preferably 0.5 to 5% by mass. If the amount is less than 0.5% by mass, sufficient adhesion at the processed part cannot be obtained, and if it exceeds 5% by mass, the moisture resistance of the chemical conversion film is lowered.
  • a preferable adhesion amount of the chemical conversion coating is 0.025 to 0.5 g / m 2 . If it is less than 0.025 g / m 2 , the adhesion with the underlying zinc-based plated steel sheet and the upper primer coating film and the corrosion resistance may decrease. If it exceeds 0.5 g / m 2 , the chemical conversion coating film is likely to be broken (peeled) when subjected to severe bending, and the corrosion resistance may be lowered.
  • a chemical conversion treatment liquid is continuously applied to a zinc-based plated steel sheet with a roll coater, and then a plate temperature of about 60 ° C. to 200 ° C. (Peak Metal: Temperature: Obtained by drying with PMT).
  • the primer coating film contains a polyester resin having a urethane bond as a main component, and contains a vanadium compound, a phosphoric acid compound, and magnesium oxide.
  • the “main component” as used herein means a component having the highest content in each component in the primer coating film.
  • polyester resin having a urethane bond a known resin such as a resin obtained by a reaction between a polyester polyol and diisocyanate or polyisocyanate having two or more isocyanate groups can be used. Also, a resin obtained by curing a resin (urethane-modified polyester resin) obtained by reacting a polyester polyol and a diisocyanate or polyisocyanate having two or more isocyanate groups in an excessive hydroxyl group state with a blocked polyisocyanate can be used.
  • a resin urethane-modified polyester resin
  • the polyester polyol can be obtained by a known method using a dehydration condensation reaction between a polyhydric alcohol component and a polybasic acid component.
  • Examples of the polyhydric alcohol include glycol and trihydric or higher polyhydric alcohol.
  • Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, hexylene glycol, 1,3-butanediol, 1,4- Butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, methylpropanediol, cyclohexanedimethanol, 3,3-diethyl-1,5- Examples include pentanediol.
  • trihydric or higher polyhydric alcohol examples include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and dipentaerythritol. These polyhydric alcohols can be used alone or in combination of two or more.
  • polybasic acid a polyvalent carboxylic acid is usually used, but a monovalent fatty acid or the like can be used in combination as necessary.
  • polycarboxylic acids include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 4-methylhexahydrophthalic acid, bicyclo [2,2,1] heptane-2,3-dicarboxylic acid, trimellitic acid, adipine Acids, sebacic acid, succinic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, pyromellitic acid, dimer acid, etc., and their acid anhydrides, and 1,4-cyclohexanedicarboxylic acid, isophthalic acid, tetrahydroisophthalic acid Hexahydroisophthalic acid, hexahydroterephthalic acid and the like. These polybasic acids can be used alone or in combination of two or more.
  • polyisocyanate compound examples include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and dimer acid diisocyanate, and xylylene diisocyanate (XDI), metaxylylene diisocyanate, tolylene diisocyanate (TDI), 4,4.
  • -Aromatic diisocyanates such as diphenylmethane diisocyanate (MDI), and cycloaliphatic diisocyanates such as isophorone diisocyanate, hydrogenated XDI, hydrogenated TDI, and hydrogenated MDI, and adducts, biurets, and isocyanurates. It is done.
  • MDI diphenylmethane diisocyanate
  • cycloaliphatic diisocyanates such as isophorone diisocyanate, hydrogenated XDI, hydrogenated TDI, and hydrogenated MDI, and adduct
  • the hydroxyl value of the polyester resin having a urethane bond is preferably 5 to 120 mgKOH / g, more preferably 7 to 100 mgKOH / g, and further preferably 10 to 80 mgKOH from the viewpoint of solvent resistance and processability. / G.
  • the number average molecular weight of the polyester resin having a urethane bond is preferably from 500 to 15,000, more preferably from 700 to 12,000, and still more preferably from 800 to 15,000, from the viewpoint of solvent resistance and processability. 10,000.
  • Polyester resin having a urethane bond has both flexibility and strength, and the effect that the primer coating film is less likely to crack when subjected to processing is obtained. Moreover, it has high affinity with the chemical conversion film containing a urethane resin, and contributes particularly to the improvement of the corrosion resistance of the processed part.
  • the primer resin contains 40 to 88% by mass of the polyester resin.
  • the binder function as the primer coating film is deteriorated, and when the amount exceeds 88% by mass, the function by the inorganic material described below, for example, the inhibitor action may be decreased.
  • Vanadium compounds act as inhibitors.
  • the vanadium compound include vanadium pentoxide, metavanadate, ammonium metavanadate, vanadium oxytrichloride, vanadium trioxide, vanadium dioxide, magnesium vanadate, vanadyl acetylacetonate, vanadium acetylacetonate, and the like.
  • a tetravalent vanadium compound or a tetravalent vanadium compound obtained by reduction or oxidation is desirable.
  • the vanadium compound added to the primer coating film may be the same as or different from the vanadium compound added to the chemical conversion coating.
  • the vanadic acid compound reacts with the vanadate ions that gradually elute into the moisture entering from the outside and the ions on the surface of the galvanized steel sheet to form a passive film with good adhesion, thereby protecting and preventing the exposed metal part. It is thought that rust action appears.
  • the content of the vanadium compound in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the inhibitor effect is lowered and the corrosion resistance is lowered, and if it exceeds 20% by mass, the moisture resistance of the primer coating film is lowered.
  • the phosphoric acid compound acts as an inhibitor.
  • phosphoric acid, ammonium salt of phosphoric acid, alkali metal salt of phosphoric acid, alkaline earth metal salt of phosphoric acid and the like can be used.
  • alkaline earth metal salts of phosphoric acid such as calcium phosphate are suitable.
  • the content of the phosphate compound in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the inhibitor effect is lowered and the corrosion resistance is lowered, and if it exceeds 20% by mass, the moisture resistance of the primer coating film is lowered.
  • Magnesium oxide has the effect of stabilizing the product produced by the initial corrosion as a sparingly soluble magnesium salt.
  • the amount of magnesium oxide added in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the above-described effect is reduced, leading to a decrease in corrosion resistance. If the amount exceeds 20% by mass, the flexibility of the primer coating film is decreased, and in particular, the corrosion resistance of the processed part may be decreased.
  • the crosslinking agent used in forming the primer coating film reacts with a polyester resin having a urethane bond to form a crosslinked coating film, and is preferably a blocked polyisocyanate compound.
  • the blocked polyisocyanate include an isocyanate group of a polyisocyanate compound, for example, an alcohol such as butanol, an oxime such as methyl ethyl ketoxime, a lactam such as ⁇ -caprolactam, a diketone such as acetoacetic acid diester, and an imidazole. And imidazoles such as 2-ethylimidazole, or those blocked with phenols such as m-cresol.
  • the elongation at break of the primer coating at 25 ° C is 20% or more. Thereby, it can suppress that a primer coating film generate
  • the tensile strength of the primer coating at 25 ° C. is 20 MPa or more. If the pressure is less than 20 MPa, the strength of the primer coating film is lowered, and the primer coating film may be peeled off when a shearing force is applied during molding.
  • the elongation at break and tensile strength of the primer coating can be measured by the following method.
  • the primer coating is applied on the tinplate so that the cured coating has a thickness of about 10 ⁇ m, and the coating that has been baked and cured for 40 seconds so that the maximum temperature reaches 230 ° C. is peeled off from the tinplate by the amalgam method to form a film. Samples for testing are prepared.
  • a tensile test was performed 5 times under the conditions of 25 ° C., a tensile speed of 4 mm / min, a distance between chucks of 40 mm, and a full scale setting of 2 kg, and the average of the elongation obtained by the 5 tests The value is the elongation at break, and the average value of the tensile strength obtained in five tests is the tensile strength.
  • the preferable thickness of the primer coating is 1.5 ⁇ m or more. If the thickness is smaller than this, the corrosion resistance is deteriorated, and the adhesion with the chemical conversion film and the top coat film is reduced.
  • the resin composition for the primer coating film can contain various known components that are usually used in the paint field, if necessary. Specifically, for example, various surface conditioners such as leveling agents and antifoaming agents, dispersants, anti-settling agents, ultraviolet absorbers, light stabilizers, silane coupling agents, various additives such as titanate coupling agents, Examples thereof include various pigments such as coloring pigments and extender pigments, glittering materials, curing catalysts, and organic solvents.
  • various surface conditioners such as leveling agents and antifoaming agents, dispersants, anti-settling agents, ultraviolet absorbers, light stabilizers, silane coupling agents, various additives such as titanate coupling agents, Examples thereof include various pigments such as coloring pigments and extender pigments, glittering materials, curing catalysts, and organic solvents.
  • the coating composition is preferably applied by a method such as roll coater coating or curtain flow coating. After the coating composition is applied, it is baked by a heating means such as hot air heating, infrared heating, induction heating, etc. to obtain a primer coating film.
  • the baking treatment is usually performed at a maximum plate temperature of about 180 to 270 ° C. and within this temperature range for about 30 seconds to 3 minutes.
  • top coat In the manufacture of a coated zinc-based plated steel sheet, generally, a top coating is applied on the primer coating film. By applying the top coating, it is possible to impart aesthetics and to provide various performances such as workability, weather resistance, chemical resistance, contamination resistance, water resistance, and corrosion resistance required for coated zinc-based plated steel sheets. Can be increased.
  • top coating used in this embodiment examples include polyester resin-based paints, silicon polyester resin-based paints, polyurethane resin-based paints, acrylic resin-based paints, and fluororesin-based paints.
  • the thickness of the top coat film is preferably 5 to 30 ⁇ m. If the thickness is less than 5 ⁇ m, it is difficult to stabilize the color appearance, and if it exceeds 30 ⁇ m, the workability deteriorates (cracking of the top coat film) is caused.
  • the top coat film has titanium oxide, petal, mica, carbon black, other various color pigments, metallic pigments such as aluminum powder and mica, extender pigments made of carbonates and sulfates, Alternatively, various fine particles such as silica fine particles, nylon resin beads and acrylic resin beads, curing catalysts such as p-toluenesulfonic acid and dibutyltin dilaurate, wax and other additives can be blended in appropriate amounts.
  • the coating composition for forming the top coat film
  • the coating composition is preferably applied by a method such as roll coater coating or curtain flow coating.
  • After coating the coating composition it is baked by a heating means such as hot air heating, infrared heating, induction heating, etc. to obtain a top coat film.
  • the baking treatment is usually performed at a maximum plate temperature of about 180 to 270 ° C. and within this temperature range for about 30 seconds to 3 minutes.
  • the galvanized steel sheets used in each test example shown in Table 1 are as follows. 1: Molten 55 mass% aluminum-zinc alloy plated steel sheet (JIS G3321, AZ150) with a plate thickness of 0.35 mm and a coating weight of 80 g / m 2 per side 2: Hot-dip zinc-5% aluminum alloy-plated steel sheet (JIS G3317, Y25) with a plate thickness of 0.35 mm and a coating weight of 130 g / m 2 per side 3: Hot dip galvanized steel sheet with a plate thickness of 0.35 mm and a coating weight of 130 g / m 2 per side (JIS G3312, Z25)
  • the chemical conversion treatment liquid shown in Table 1 was formed by applying the chemical conversion treatment liquid to the surface of the galvanized steel sheet shown in Table 1 using a roll coater and drying. At that time, it was dried at an ultimate plate temperature of 90 ° C. using a hot air drying furnace to form a chemical conversion treatment film.
  • a primer paint was applied onto the chemical conversion coating film with a bar coater, and baked at a steel plate reaching temperature of 230 ° C. for a baking time of 35 seconds to form various primer coating films shown in Table 1. Further, the top coating composition shown in Table 1 is applied with a bar coater so as to have the dry film thickness shown in Table 1, and the steel sheet is baked at a temperature of 230 ° C. to 260 ° C. for a baking time of 40 seconds. A film was formed. Thus, various coated galvanized steel sheets were obtained.
  • An organic vanadium compound chelated with acetylacetone was used as the vanadium compound, ammonium zirconium carbonate was used as the zirconium compound, and ammonium fluoride was used as the fluorine compound.
  • the coating material for forming the primer coating film was produced by the following method.
  • a polyester resin ( ⁇ ) having a urethane bond as a main component a urethane-modified polyester resin cured with blocked isocyanate was used.
  • the urethane-modified polyester resin was obtained by reacting 455 parts by mass of a polyester resin and 45 parts by mass of isophorone diisocyanate.
  • the resin acid value of the urethane-modified polyester resin was 3, the number average molecular weight was 5,600, and the hydroxyl value was 36.
  • polyester resin used when manufacturing the said urethane-modified polyester resin was manufactured as follows.
  • a flask equipped with a stirrer, a rectifying column, a water separator, a condenser and a thermometer was charged with 320 parts by mass of isophthalic acid, 200 parts by mass of adipic acid, 60 parts by mass of trimethylolpropane, and 420 parts by mass of cyclohexanedimethanol.
  • the mixture was heated and stirred, and the temperature was raised from 160 ° C. to 230 ° C. at a constant rate over 4 hours while distilling out the generated condensed water to the outside of the system.
  • urethane cured polyester resin ( ⁇ ) whose elongation at break was outside the present invention
  • melamine cured polyester resin ( ⁇ ) and urethane cured epoxy resin ( ⁇ ) which were resins outside the present invention
  • vanadium compound magnesium vanadate was used, and as the phosphate compound, calcium phosphate was used.
  • a primer coating was obtained by stirring for about 1 hour in a ball mill.
  • the content of each component in the primer coating was as shown in Table 1.
  • Comparative Examples 13 and 14 a urethane-cured epoxy resin primer coating film containing 25% by mass of strontium chromate was used.
  • (Top coat) Resins for the top coat film shown in Table 1 are as follows. I: Melamine cured polyester paint “Precolor HD0030HR” (BASF Japan Ltd.) II: Organosol-based baking type fluororesin paint “Precolor No. 8800HR” (made by BASF Japan Ltd.) in which polyvinylidene fluoride and acrylic resin are in a mass ratio of 80:20
  • the coated galvanized steel sheet of the present invention is suitable for applications such as interior / exterior materials for building materials such as roofs, walls, and shutters, and home appliances such as air conditioner outdoor units.

Abstract

Provided is a chromate-free coated galvanized steel sheet which exhibits excellent corrosion resistance, especially excellent corrosion resistance in a cut end surface or a processed portion such as a bent portion. A coated galvanized steel sheet according to the present invention is obtained by sequentially forming, on at least one surface of a galvanized steel sheet, a chemical conversion coating film that does not contain a chromate compound, a primer coating film that does not contain a chromate compound, and a top coating film. The chemical conversion coating film contains an anionic urethane resin (a) having an ester bond, an epoxy resin (b) having a bisphenol skeleton, a vanadium compound, a zirconium compound and a fluorine compound, respectively in predetermined amounts. The primer coating film is mainly composed of a polyester resin having a urethane bond, and contains a vanadium compound, a phosphoric acid compound and magnesium oxide. The primer coating film has an elongation at break at 25°C of 20% or more and a tensile strength at 25°C of 20 MPa or more.

Description

塗装亜鉛系めっき鋼板Painted galvanized steel sheet
　本発明は、耐食性、特に折り曲げ等の加工部や切断端面における耐食性に優れたクロメートフリーの塗装亜鉛系めっき鋼板に関する。 The present invention relates to a chromate-free coated galvanized steel sheet excellent in corrosion resistance, in particular, corrosion resistance in a processed part such as a bend and a cut end face.
　亜鉛または亜鉛を含む合金をめっきした鋼板（以下「亜鉛系めっき鋼板」と略す。）の表面に、化成処理皮膜およびプライマー塗膜を形成し、その上に様々な塗膜を形成した塗装亜鉛系めっき鋼板は、品質の安定性や需要家での塗装工程省略による合理化など多くのメリットがあることから、建築物の屋根・壁などの外装材やパーティション等の内装材、電機機器製品の各部材、などとして広く使用されている。通常、このような塗装亜鉛系めっき鋼板は、プレス成形やロール成形、あるいはエンボス成形によって９０度曲げあるいは１８０度曲げなどを含む様々な加工を施され、かつ使用後の長期の塗膜耐久性能が要求される。 Zinc or zinc-containing alloy coated steel sheet (hereinafter abbreviated as “zinc-based plated steel sheet”) is formed with a chemical conversion coating and a primer coating on which various coatings are formed. Plated steel sheet has many advantages such as stability of quality and rationalization by omitting the painting process by customers. Therefore, exterior materials such as roofs and walls of buildings, interior materials such as partitions, and each component of electrical equipment products Widely used as, etc. Usually, such coated galvanized steel sheets are subjected to various processing including 90-degree bending or 180-degree bending by press forming, roll forming, or embossing, and have long-term coating durability performance after use. Required.
　これらの要求に応えるため、亜鉛系めっき鋼板にクロメートを含有する化成処理を施し、プライマー塗膜中にクロメート系防錆顔料を含有させ、その上に上塗り塗膜として、熱硬化型のポリエステル系樹脂塗膜やより耐候性の高い要求に対してはフッ素系樹脂塗膜を形成した塗装亜鉛系めっき鋼板が適用されているのが一般的であった。 In order to meet these requirements, a zinc-plated steel sheet is subjected to a chemical conversion treatment containing chromate, a chromate-based anticorrosive pigment is incorporated into the primer coating, and a thermosetting polyester resin as a top coat on top. In general, a coated zinc-based plated steel sheet on which a fluororesin coating film is formed is applied to a coating film or a request having higher weather resistance.
　しかし、昨今このような塗装亜鉛系めっき鋼板について、環境負荷物質であるクロメートを使用することが問題視されており、クロメートを含まないクロメートフリーの塗装亜鉛系めっき鋼板が強く望まれている。これらのニーズに対応した技術として、特許文献１～４が提案されている。 However, recently, with respect to such coated zinc-based plated steel sheets, the use of chromate, which is an environmentally hazardous substance, has been regarded as a problem, and chromate-free coated zinc-based plated steel sheets that do not contain chromate are strongly desired. Patent documents 1 to 4 have been proposed as technologies corresponding to these needs.
特開２００８－２９１１６２号公報JP 2008-291116 A 特開２００９－１２７０５７号公報JP 2009-127057 A 特開２０１４－２１４３１５号公報JP 2014-214315 A 特開２００５－１６９７６５号公報JP 2005-169765 A
　特許文献１には、プライマー塗膜形成のためにモリブデン化合物などの非クロメート系防錆顔料を配合した塗料組成物を、亜鉛めっき鋼板に化成処理皮膜を介して塗装した塗装亜鉛めっき鋼板が記載されている。しかしながら、適用される亜鉛めっき鋼板が亜鉛を９４％以上含むものに限定されており、また化成処理皮膜としてクロメート系を適用することから、クロメートフリーの塗装亜鉛系めっき鋼板とはいえないものであった。 Patent Document 1 describes a coated galvanized steel sheet obtained by coating a galvanized steel sheet with a coating composition containing a non-chromate rust preventive pigment such as a molybdenum compound for forming a primer coating film via a chemical conversion coating. ing. However, the applied galvanized steel sheet is limited to those containing 94% or more of zinc, and since chromate is applied as the chemical conversion coating, it cannot be said to be a chromate-free coated galvanized steel sheet. It was.
　特許文献２は、樹脂とクロメートフリー系防錆顔料からなる下地処理剤（化成処理皮膜）に関するものである。特許文献２は、塗装を施さない一次防錆用の技術であり、塗装亜鉛系めっき鋼板の化成処理皮膜として適用した場合は十分な耐食性が得られない。 Patent Document 2 relates to a base treatment agent (chemical conversion treatment film) comprising a resin and a chromate-free rust preventive pigment. Patent Document 2 is a technique for primary rust prevention without coating, and sufficient corrosion resistance cannot be obtained when applied as a chemical conversion treatment film of a coated galvanized steel sheet.
　特許文献３は、樹脂とクロメートフリー系防錆顔料からなる下地処理剤（化成処理皮膜）を用いた塗装亜鉛系めっき鋼板に関するものである。特許文献３は、プライマーを含めたトータル防錆設計を提案しているが、特に加工部の耐食性に関しては、十分とはいえない。 Patent Document 3 relates to a coated galvanized steel sheet using a base treatment agent (chemical conversion coating) composed of a resin and a chromate-free rust preventive pigment. Patent Document 3 proposes a total rust prevention design including a primer, but it cannot be said that the corrosion resistance of a processed part is particularly sufficient.
　特許文献４は、特定のいずれも非クロメート系の防錆顔料を含んだ化成処理皮膜とプライマー塗膜を形成した塗装亜鉛系めっき鋼板で、トータルでの防錆性向上を狙った技術が記載されている。しかし、特に加工部の耐食性には十分な効果が得られない。 Patent Document 4 is a coated zinc-plated steel sheet on which a specific chemical conversion treatment film containing a non-chromate anti-corrosion pigment and a primer film are formed, and a technique aimed at improving the total anti-rust property is described. ing. However, a sufficient effect cannot be obtained particularly on the corrosion resistance of the processed part.
　このように、従来のクロメートフリーの塗装亜鉛系めっき鋼板は、クロメートを含有する塗装亜鉛系めっき鋼板に比べて耐食性が劣るか、あるいはクロメートを含有する塗装亜鉛系めっき鋼板よりプライマー塗膜の厚さを著しく厚くする必要があり、経済性に劣るものであった。 Thus, the conventional chromate-free coated zinc-based plated steel sheet is inferior in corrosion resistance to the coated zinc-based plated steel sheet containing chromate, or the primer coating thickness is higher than that of the coated zinc-based plated steel sheet containing chromate. It was necessary to remarkably increase the thickness, which was inferior in economic efficiency.
　そこで本発明は、上記課題に鑑み、耐食性、特に折り曲げ等の加工部や切断端面における耐食性に優れたクロメートフリーの塗装亜鉛系めっき鋼板を提供すること目的とする。 Therefore, in view of the above problems, the present invention has an object to provide a chromate-free coated zinc-based plated steel sheet that is excellent in corrosion resistance, in particular, corrosion resistance in a processed part such as a bend and a cut end surface.
　本発明者らは、下記に示すように、特定の共通要素を含む化成処理皮膜とプライマー塗膜を形成することにより上記課題を解決できることを見出し、本発明に至った。すなわち、本発明の要旨構成は以下のとおりである。 The present inventors have found that the above problems can be solved by forming a chemical conversion treatment film and a primer coating film containing specific common elements as shown below, and have reached the present invention. That is, the gist configuration of the present invention is as follows.
　（１）亜鉛系めっき鋼板と、
　該亜鉛系めっき鋼板の少なくとも片面に形成された、クロメート系化合物を含有しない化成処理皮膜と、
　該化成処理皮膜上に形成された、クロメート系化合物を含有しないプライマー塗膜と、
　該プライマー塗膜上に形成された上塗り塗膜と、
を有する塗装亜鉛系めっき鋼板であって、
　前記化成処理皮膜が樹脂成分と無機成分の複合体であり、前記樹脂成分として、エステル結合を有するアニオンウレタン樹脂（a）、およびビスフェノール骨格を有するエポキシ樹脂（b）を合計で３０～５０質量％含有し、前記（a）と前記（b）の配合比率が、質量％で３：９７～６０：４０の範囲内であり、前記無機成分として、バナジウム化合物を２～１０質量％、ジルコニウム化合物を４０～６０質量％、およびフッ素化合物を０．５～５質量％含有し、
　前記プライマー塗膜がウレタン結合を有するポリエステル樹脂を主成分とし、バナジウム化合物、リン酸化合物、および酸化マグネシウムを含有し、前記プライマー塗膜の、２５℃における破断伸びが２０％以上であり、かつ２５℃における抗張力が２０ＭＰａ以上である
ことを特徴とする塗装亜鉛系めっき鋼板。 (1) a zinc-based plated steel sheet;
A chemical conversion treatment film not containing a chromate compound formed on at least one surface of the galvanized steel sheet;
A primer coating film formed on the chemical conversion coating film and containing no chromate compound;
A top coat film formed on the primer coat film;
A coated galvanized steel sheet having
The chemical conversion film is a composite of a resin component and an inorganic component, and as the resin component, an anionic urethane resin (a) having an ester bond and an epoxy resin (b) having a bisphenol skeleton in total 30 to 50% by mass And the blending ratio of (a) and (b) is in the range of 3:97 to 60:40 by mass%, and the inorganic component is 2 to 10 mass% of vanadium compound and zirconium compound. 40 to 60% by mass, and 0.5 to 5% by mass of a fluorine compound,
The primer coating film contains a polyester resin having a urethane bond as a main component, contains a vanadium compound, a phosphoric acid compound, and magnesium oxide, and the elongation at break at 25 ° C. of the primer coating film is 20% or more, and 25 A coated galvanized steel sheet having a tensile strength at 20 ° C. of 20 MPa or more.
　（２）前記プライマー塗膜中に、前記ポリエステル樹脂が４０～８８質量％、前記バナジウム化合物が４～２０質量％、前記リン酸化合物が４～２０質量％、前記酸化マグネシウムが４～２０質量％含有される上記（１）に記載の塗装亜鉛系めっき鋼板。 (2) In the primer coating, the polyester resin is 40 to 88% by mass, the vanadium compound is 4 to 20% by mass, the phosphoric acid compound is 4 to 20% by mass, and the magnesium oxide is 4 to 20% by mass. The coated galvanized steel sheet according to (1) above.
　（３）前記化成処理皮膜の付着量が０．０２５～０．５ｇ／ｍ２、前記プライマー塗膜の厚さが１．５μｍ以上である上記（１）または（２）に記載の塗装亜鉛系めっき鋼板。 (3) The coated zinc-based coating as described in (1) or (2) above, wherein the chemical conversion coating has an adhesion amount of 0.025 to 0.5 g / m 2 and the primer coating has a thickness of 1.5 μm or more. Plated steel sheet.
　本発明の塗装亜鉛系めっき鋼板は、環境安全面で有利なクロメートフリーでありながら、特に折り曲げ等の加工部や切断端面における優れた耐食性を得ることができる。そのため、本発明の塗装亜鉛系めっき鋼板を建材分野に適用した場合、屋根成形品の折り曲げ部や、壁材のエンボス加工部や角スパン曲げ部において長期間の腐食を抑制するができ、塗り替えや補修などの維持費を大幅に削減できる。 The coated galvanized steel sheet of the present invention is excellent in corrosion resistance particularly in the processed part such as bending and the cut end face while being chromate-free which is advantageous in terms of environmental safety. Therefore, when the coated galvanized steel sheet of the present invention is applied to the building material field, long-term corrosion can be suppressed at the bent part of the roof molded product, the embossed part of the wall material, and the corner span bent part. Maintenance costs such as repairs can be greatly reduced.
　本発明の一実施形態による塗装亜鉛系めっき鋼板は、亜鉛系めっき鋼板と、この亜鉛系めっき鋼板の少なくとも片面に形成された、クロメート系化合物を含有しない化成処理皮膜と、この化成処理皮膜上に形成された、クロメート系化合物を含有しないプライマー塗膜と、このプライマー塗膜上に形成された上塗り塗膜と、を有する。 A coated galvanized steel sheet according to an embodiment of the present invention includes a galvanized steel sheet, a chemical conversion film that does not contain a chromate compound formed on at least one surface of the galvanized steel sheet, and the chemical conversion film. A primer coating film that does not contain a chromate compound and a top coating film formed on the primer coating film;
　（亜鉛系めっき鋼板）
　本発明において、ベースとなる亜鉛系めっき鋼板としては、そのめっき層中に亜鉛を含有する鋼板であればよく、特に制限はないが、溶融亜鉛めっき鋼板（ＧＩ）またはこれを合金化した合金化溶融亜鉛めっき鋼板（ＧＡ）、電気亜鉛めっき鋼板（ＥＧ）等の亜鉛めっき鋼板、Ｚｎ－Ｎｉめっき鋼板、Ｚｎ－Ａｌめっき鋼板（例えば、Ｚｎ－５質量％Ａｌ合金めっき鋼板、Ｚｎ－５５質量％Ａｌ合金めっき鋼板）、Ｚｎ－Ａｌ－Ｍｇめっき鋼板などを用いることが可能である。 (Zinc-based plated steel sheet)
In the present invention, the zinc-based plated steel sheet used as a base is not particularly limited as long as it is a steel sheet containing zinc in the plating layer, but is not limited, but a hot-dip galvanized steel sheet (GI) or an alloyed alloy thereof. Galvanized steel sheet such as hot dip galvanized steel sheet (GA), electrogalvanized steel sheet (EG), Zn—Ni plated steel sheet, Zn—Al plated steel sheet (eg, Zn-5 mass% Al alloy plated steel sheet, Zn-55 mass%) Al alloy-plated steel sheet), Zn—Al—Mg-plated steel sheet, and the like can be used.
　また、亜鉛めっき層に少量の異種金属元素あるいは不純物としてニッケル、コバルト、マンガン、鉄、モリブデン、タングステン、チタン、クロム、アルミニウム、マグネシウム、鉛、アンチモン、錫、銅の１種または２種以上を含有してもよい。また、上記亜鉛めっき層のうち、同種または異種のものを２層以上めっきしてもよい。 Also, the zinc plating layer contains one or more kinds of nickel, cobalt, manganese, iron, molybdenum, tungsten, titanium, chromium, aluminum, magnesium, lead, antimony, tin, copper as a small amount of different metal elements or impurities May be. Also, two or more of the same or different galvanized layers may be plated.
　（化成処理皮膜）
　化成処理皮膜は樹脂成分と無機成分の複合体であり、樹脂成分として、エステル結合を有するアニオンウレタン樹脂（a）、およびビスフェノール骨格を有するエポキシ樹脂（b）を含有し、無機成分として、バナジウム化合物、ジルコニウム化合物、およびフッ素化合物を含有する。 (Chemical conversion coating)
The chemical conversion coating is a composite of a resin component and an inorganic component, which contains an anionic urethane resin (a) having an ester bond as an resin component and an epoxy resin (b) having a bisphenol skeleton, and a vanadium compound as an inorganic component. , A zirconium compound, and a fluorine compound.
　エステル結合を有するアニオンウレタン樹脂（a）としては、ポリエステルポリオールと、イソシアネート基を２個以上もつ、ジイソシアネートまたはポリイソシアネートとを反応させ、ジメチロールアルキル酸を共重合して得られる樹脂が適用でき、公知の方法で水などの液に分散することにより化成処理液を得ることができる。 As the anionic urethane resin (a) having an ester bond, a resin obtained by reacting a polyester polyol with diisocyanate or polyisocyanate having two or more isocyanate groups and copolymerizing dimethylol alkyl acid can be applied. A chemical conversion treatment liquid can be obtained by dispersing in a liquid such as water by a known method.
　ポリエステルポリオールとしては、グリコール成分と、ヒドロキシルカルボン酸のエステル形成誘導体などの酸成分とから脱水縮合反応によって得られるポリエステル、ε－カプロラクトン等の環状エステル化合物の開環重合反応によって得られるポリエステル、およびこれら共重合ポリエステルが挙げられる。ポリイソシアネートとしては、芳香族ポリイソシアネート、脂肪族ポリイソシアネート、脂環式ポリイソシアネート等が挙げられる。前記芳香族ポリイソシアネートとしては、例えば、２，４－トリレンジイソシアネート、２，６－トリレンジイソシアネート、ｍ－キシレンジイソシアネート、ジフェニルメタンジイソシアネート、２，４－ジフェニルメタンジイソシアネート、２，２－ジフェニルメタンジイソシアネート、トリフェニルメタントリイソシアネート、ポリメチレンポリフェニルポリイソシアネート、ナフタレンジイソシアネート、およびこれらの誘導体（例えばポリオール類との反応により得られたプレポリマー類、ジフェニルメタンジイソシアネートのカルボジイミド化合物等の変性ポリイソシアネート類等）等が挙げられる。具体的には、ジフェニルメタンジイソシアネートの一部をカルボジイミド化した混合物等が挙げられる。これらポリエステルポリオールと、ジイソシアネートまたはポリイソシアネートとを反応させてウレタンを合成する際に、ジメチロールアルキル酸を共重合し、自己乳化させて水溶化（水分散）させることで、本発明に用いるエステル結合を有するアニオンウレタン樹脂（a）を得ることができる。 Polyester polyols include polyesters obtained by dehydration condensation reaction from glycol components and acid components such as ester-forming derivatives of hydroxylcarboxylic acid, polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ε-caprolactone, and the like. Copolyester is mentioned. Examples of the polyisocyanate include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate. Examples of the aromatic polyisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-xylene diisocyanate, diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, and triphenyl. Methane triisocyanate, polymethylene polyphenyl polyisocyanate, naphthalene diisocyanate, and derivatives thereof (for example, prepolymers obtained by reaction with polyols, modified polyisocyanates such as carbodiimide compounds of diphenylmethane diisocyanate, etc.) . Specific examples include a mixture obtained by carbodiimidizing a part of diphenylmethane diisocyanate. When synthesizing urethane by reacting these polyester polyols with diisocyanate or polyisocyanate, dimethylol alkyl acid is copolymerized, self-emulsified and water-solubilized (water-dispersed), and ester bonds used in the present invention An anionic urethane resin (a) having can be obtained.
　ビスフェノール骨格を有するエポキシ樹脂（b）は、公知の樹脂を用いることができ、公知の方法で水などの液に分散することにより化成処理液を得ることができる。 As the epoxy resin (b) having a bisphenol skeleton, a known resin can be used, and a chemical conversion treatment liquid can be obtained by dispersing in a liquid such as water by a known method.
　樹脂成分は化成処理皮膜のバインダーとして作用し、エステル結合を有するアニオンウレタン樹脂（a）は、可撓性があるので加工を受けた際に化成処理皮膜が破壊（剥離）しにくくなる効果があり、エポキシ樹脂（b）は、下地の亜鉛系めっき鋼板および上層のプライマー塗膜との密着性を向上する効果がある。樹脂成分は、化成処理皮膜中に合計３０～５０質量％含むものとする。３０質量％未満では化成処理皮膜のバインダー効果が低下し、５０質量％を超えると、下記に示す無機成分による機能、例えばインヒビター作用が低下するためである。 The resin component acts as a binder for the chemical conversion coating, and the anionic urethane resin (a) having an ester bond is flexible so that the chemical conversion coating is less likely to break (peel) when processed. The epoxy resin (b) has an effect of improving adhesion to the underlying zinc-based plated steel sheet and the upper primer coating film. A total of 30 to 50% by mass of the resin component is included in the chemical conversion film. When the amount is less than 30% by mass, the binder effect of the chemical conversion film is lowered. When the amount exceeds 50% by mass, the function by the inorganic component described below, for example, the inhibitor action is lowered.
　エステル結合を有するアニオンウレタン樹脂（a）とビスフェノール骨格を有するエポキシ樹脂（b）の配合比率は、樹脂全体を１００とした場合、質量％で３：９７～６０：４０の範囲内とする。この範囲外では、化成処理皮膜としての可撓性の低下に伴い、密着性が低下するからである。 The compounding ratio of the anionic urethane resin (a) having an ester bond and the epoxy resin (b) having a bisphenol skeleton is within a range of 3:97 to 60:40 in terms of mass% when the total resin is 100. Outside this range, the adhesiveness decreases as the flexibility of the chemical conversion coating decreases.
　バナジウム化合物は、化成処理液中に添加して防錆剤（インヒビター）として作用する。バナジウム化合物としては、五酸化バナジウム、メタバナジン酸、メタバナジン酸アンモニウム、オキシ三塩化バナジウム、三酸化バナジウム、二酸化バナジウム、バナジン酸マグネシウム、バナジルアセチルアセトネート、バナジウムアセチルアセトネートなどが挙げられる。特に４価のバナジウム化合物、または還元もしくは酸化することによって得られる４価のバナジウム化合物が望ましい。 The vanadium compound acts as a rust inhibitor (inhibitor) when added to the chemical conversion solution. Examples of vanadium compounds include vanadium pentoxide, metavanadate, ammonium metavanadate, vanadium oxytrichloride, vanadium trioxide, vanadium dioxide, magnesium vanadate, vanadyl acetylacetonate, vanadium acetylacetonate, and the like. In particular, a tetravalent vanadium compound or a tetravalent vanadium compound obtained by reduction or oxidation is desirable.
　化成処理皮膜中のバナジウム化合物の含有量は、２～１０質量％であることが好ましい。２質量％未満ではインヒビター効果が低下して耐食性の低下を招き、１０質量％を超えると化成処理皮膜の耐湿性の低下を招くからである。 The content of the vanadium compound in the chemical conversion film is preferably 2 to 10% by mass. If the amount is less than 2% by mass, the inhibitor effect is reduced, resulting in a decrease in corrosion resistance. If the amount exceeds 10% by mass, the moisture resistance of the chemical conversion film is decreased.
　ジルコニウム化合物は、化成処理液中に添加され、めっき金属との反応や樹脂成分との共存により、化成処理皮膜としての強度向上および耐食性向上が期待でき、さらにはジルコニウム化合物自体が緻密な化成処理皮膜の形成に寄与し、被覆性に富むことからバリア効果が期待できる。ジルコニウム化合物としては、硫酸ジルコニウム、炭酸ジルコニウム、硝酸ジルコニウム、乳酸ジルコニウム、酢酸ジルコニウム、塩化ジルコニウムなどの中和塩、などが挙げられる。 Zirconium compounds are added to the chemical conversion treatment liquid, and can be expected to improve the strength and corrosion resistance of the chemical conversion treatment film due to the reaction with the plating metal and the coexistence with the resin component. Furthermore, the zirconium compound itself is a dense chemical conversion treatment film. The barrier effect can be expected from the fact that it contributes to the formation of the film and is rich in coverage. Examples of the zirconium compound include neutralized salts such as zirconium sulfate, zirconium carbonate, zirconium nitrate, zirconium lactate, zirconium acetate, and zirconium chloride.
　化成処理皮膜中のジルコニウム化合物の含有量は、４０～６０質量％であることが好ましい。４０質量％未満では化成処理皮膜としての強度や耐食性の低下を招き、６０質量％を超えると化成処理皮膜が脆化して、厳しい加工を受けた場合に化成処理皮膜の破壊や剥離が生じるからである。 The content of the zirconium compound in the chemical conversion film is preferably 40 to 60% by mass. If it is less than 40% by mass, the strength and corrosion resistance of the chemical conversion coating will be reduced, and if it exceeds 60% by mass, the chemical conversion coating will become brittle and the chemical conversion coating will be destroyed or peeled off when subjected to severe processing. is there.
　フッ素化合物は、化成処理液中に添加され、亜鉛系めっき鋼板との密着性付与剤として作用する。フッ素化合物としては、例えば、アンモニウム塩、ナトリウム塩、カリウム塩などのフッ化物塩、あるいはフッ化第一鉄、フッ化第二鉄等のフッ素化合物を用いることができる。特にフッ化アンモニウムや、フッ化ナトリウムおよびフッ化カリウム等のフッ化物塩が望ましい。 Fluorine compound is added to the chemical conversion treatment liquid and acts as an adhesiveness imparting agent with the galvanized steel sheet. As the fluorine compound, for example, a fluoride salt such as ammonium salt, sodium salt, or potassium salt, or a fluorine compound such as ferrous fluoride or ferric fluoride can be used. In particular, ammonium fluoride and fluoride salts such as sodium fluoride and potassium fluoride are desirable.
　化成処理皮膜中のフッ素化合物の含有量は、０．５～５質量％であることが好ましい。０．５質量％未満では加工部での密着性が充分に得られず、５質量％を超えると化成処理皮膜の耐湿性が低下するからである。 The content of the fluorine compound in the chemical conversion film is preferably 0.5 to 5% by mass. If the amount is less than 0.5% by mass, sufficient adhesion at the processed part cannot be obtained, and if it exceeds 5% by mass, the moisture resistance of the chemical conversion film is lowered.
　化成処理皮膜の好ましい付着量は、０．０２５～０．５ｇ／ｍ２である。０．０２５ｇ／ｍ２未満では下地の亜鉛系めっき鋼板および上層のプライマー塗膜との密着性の低下や耐食性の低下が生じ得る。０．５ｇ／ｍ２を超えると厳しい曲げ加工を受けた場合に化成処理皮膜が破壊（剥離）しやすくなり、やはり耐食性が低下することがある。 A preferable adhesion amount of the chemical conversion coating is 0.025 to 0.5 g / m 2 . If it is less than 0.025 g / m 2 , the adhesion with the underlying zinc-based plated steel sheet and the upper primer coating film and the corrosion resistance may decrease. If it exceeds 0.5 g / m 2 , the chemical conversion coating film is likely to be broken (peeled) when subjected to severe bending, and the corrosion resistance may be lowered.
　化成処理皮膜は、亜鉛系めっき鋼板に化成処理液をロールコーターなどで連続的に塗装し、その後、熱風や誘導加熱などを用いて、６０℃～２００℃程度の到達板温（Peak Metal Temperature：ＰＭＴ）で乾燥させることにより得られる。 For the chemical conversion coating, a chemical conversion treatment liquid is continuously applied to a zinc-based plated steel sheet with a roll coater, and then a plate temperature of about 60 ° C. to 200 ° C. (Peak Metal: Temperature: Obtained by drying with PMT).
　（プライマー塗膜）
　プライマー塗膜は、ウレタン結合を有するポリエステル樹脂を主成分とし、バナジウム化合物、リン酸化合物、および酸化マグネシウムを含有する。なお、ここでいう「主成分」とは、プライマー塗膜中の各成分中最も含有量が多い成分であることを意味する。 (Primer coating)
The primer coating film contains a polyester resin having a urethane bond as a main component, and contains a vanadium compound, a phosphoric acid compound, and magnesium oxide. The “main component” as used herein means a component having the highest content in each component in the primer coating film.
　ウレタン結合を有するポリエステル樹脂としては、ポリエステルポリオールと、イソシアネート基を２個以上もつ、ジイソシアネートまたはポリイソシアネートとの反応によって得られる樹脂など、公知のものが使用できる。また、ポリエステルポリオールと、イソシアネート基を２個以上もつ、ジイソシアネートまたはポリイソシアネートとを水酸基過剰な状態で反応させた樹脂（ウレタン変性ポリエステル樹脂）をブロック化ポリイソシアネートで硬化させた樹脂も使用できる。 As the polyester resin having a urethane bond, a known resin such as a resin obtained by a reaction between a polyester polyol and diisocyanate or polyisocyanate having two or more isocyanate groups can be used. Also, a resin obtained by curing a resin (urethane-modified polyester resin) obtained by reacting a polyester polyol and a diisocyanate or polyisocyanate having two or more isocyanate groups in an excessive hydroxyl group state with a blocked polyisocyanate can be used.
　ポリエステルポリオールは、多価アルコール成分と多塩基酸成分との脱水縮合反応を利用した、公知の方法により得ることができる。 The polyester polyol can be obtained by a known method using a dehydration condensation reaction between a polyhydric alcohol component and a polybasic acid component.
　多価アルコールとして、グリコール及び３価以上の多価アルコールが挙げられる。グリコールとして、例えば、エチレングリコール、プロピレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ジプロピレングリコール、ポリエチレングリコール、ポリプロピレングリコール、ネオペンチルグリコール、ヘキシレングリコール、１，３－ブタンジオール、１，４－ブタンジオール、１，５－ペンタンジオール、１，６－ヘキサンジオール、２－ブチル－２－エチル－１，３－プロパンジオール、メチルプロパンジオール、シクロヘキサンジメタノール、３，３－ジエチル－１，５－ペンタンジオールなどが挙げられる。また、３価以上の多価アルコールとして、例えば、グリセリン、トリメチロールエタン、トリメチロールプロパン、ペンタエリスリトール、ジペンタエリスリトールなどが挙げられる。これらの多価アルコールは、単独で使用することもでき、２種以上組み合わせて使用することもできる。 Examples of the polyhydric alcohol include glycol and trihydric or higher polyhydric alcohol. Examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, hexylene glycol, 1,3-butanediol, 1,4- Butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-butyl-2-ethyl-1,3-propanediol, methylpropanediol, cyclohexanedimethanol, 3,3-diethyl-1,5- Examples include pentanediol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and dipentaerythritol. These polyhydric alcohols can be used alone or in combination of two or more.
　多塩基酸として、通常は多価カルボン酸が使用されるが、必要に応じて１価の脂肪酸などを併用することができる。多価カルボン酸として、例えば、フタル酸、テトラヒドロフタル酸、ヘキサヒドロフタル酸、４－メチルヘキサヒドロフタル酸、ビシクロ［２，２，１］ヘプタン－２，３－ジカルボン酸、トリメリット酸、アジピン酸、セバシン酸、コハク酸、アゼライン酸、フマル酸、マレイン酸、イタコン酸、ピロメリット酸、ダイマー酸など、及びこれらの酸無水物、並びに１，４－シクロヘキサンジカルボン酸、イソフタル酸、テトラヒドロイソフタル酸、ヘキサヒドロイソフタル酸、ヘキサヒドロテレフタル酸などが挙げられる。これらの多塩基酸は、単独で使用することもでき、２種以上組み合わせて使用することもできる。 As the polybasic acid, a polyvalent carboxylic acid is usually used, but a monovalent fatty acid or the like can be used in combination as necessary. Examples of polycarboxylic acids include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 4-methylhexahydrophthalic acid, bicyclo [2,2,1] heptane-2,3-dicarboxylic acid, trimellitic acid, adipine Acids, sebacic acid, succinic acid, azelaic acid, fumaric acid, maleic acid, itaconic acid, pyromellitic acid, dimer acid, etc., and their acid anhydrides, and 1,4-cyclohexanedicarboxylic acid, isophthalic acid, tetrahydroisophthalic acid Hexahydroisophthalic acid, hexahydroterephthalic acid and the like. These polybasic acids can be used alone or in combination of two or more.
　ポリイソシアネート化合物としては、例えば、ヘキサメチレンジイソシアネート、トリメチルヘキサメチレンジイソシアネート、ダイマー酸ジイソシアネートなどの脂肪族ジイソシアネート、そして、キシリレンジイソシアネート（ＸＤＩ)、メタキシリレンジイソシアネート、トリレンジイソシアネート（ＴＤＩ)、４，４－ジフェニルメタンジイソシアネート（ＭＤＩ)などの芳香族ジイソシアネート、さらに、イソホロンジイソシアネート、水素化ＸＤＩ、水素化ＴＤＩ、水素化ＭＤＩなどの環状脂肪族ジイソシアネート、及びこれらのアダクト体、ビウレット体、イソシアヌレート体などが挙げられる。これらのポリイソシアネート化合物は、単独で使用することもでき、２種以上組み合わせて使用することもできる。 Examples of the polyisocyanate compound include aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and dimer acid diisocyanate, and xylylene diisocyanate (XDI), metaxylylene diisocyanate, tolylene diisocyanate (TDI), 4,4. -Aromatic diisocyanates such as diphenylmethane diisocyanate (MDI), and cycloaliphatic diisocyanates such as isophorone diisocyanate, hydrogenated XDI, hydrogenated TDI, and hydrogenated MDI, and adducts, biurets, and isocyanurates. It is done. These polyisocyanate compounds can be used alone or in combination of two or more.
　ウレタン結合を有するポリエステル樹脂の水酸基価は、耐溶剤性、加工性などの点から、好ましくは５～１２０ｍｇＫＯＨ／ｇであり、より好ましくは、７～１００ｍｇＫＯＨ／ｇであり、さらに好ましくは１０～８０ｍｇＫＯＨ／ｇである。 The hydroxyl value of the polyester resin having a urethane bond is preferably 5 to 120 mgKOH / g, more preferably 7 to 100 mgKOH / g, and further preferably 10 to 80 mgKOH from the viewpoint of solvent resistance and processability. / G.
　ウレタン結合を有するポリエステル樹脂の数平均分子量は、耐溶剤性、加工性などの点から、好ましくは５００～１５，０００であり、より好ましくは、７００～１２，０００であり、さらに好ましくは８００～１０，０００である。 The number average molecular weight of the polyester resin having a urethane bond is preferably from 500 to 15,000, more preferably from 700 to 12,000, and still more preferably from 800 to 15,000, from the viewpoint of solvent resistance and processability. 10,000.
　ウレタン結合を有するポリエステル樹脂は、可撓性と強度を兼ね備えており、加工を受けた際にプライマー塗膜にクラックが発生しにくいなどの効果が得られる。また、ウレタン樹脂を含有する化成処理皮膜との親和性が高く、特に加工部の耐食性向上に寄与する。 Polyester resin having a urethane bond has both flexibility and strength, and the effect that the primer coating film is less likely to crack when subjected to processing is obtained. Moreover, it has high affinity with the chemical conversion film containing a urethane resin, and contributes particularly to the improvement of the corrosion resistance of the processed part.
　プライマー塗膜中に、ポリエステル樹脂は４０～８８質量％含むことが好ましい。４０質量％未満では、プライマー塗膜としてのバインダー機能が低下し、８８質量％を超えると、下記に示す無機物による機能、例えばインヒビター作用が低下することがある。 It is preferable that the primer resin contains 40 to 88% by mass of the polyester resin. When the amount is less than 40% by mass, the binder function as the primer coating film is deteriorated, and when the amount exceeds 88% by mass, the function by the inorganic material described below, for example, the inhibitor action may be decreased.
　バナジウム化合物は、インヒビターとして作用する。バナジウム化合物としては、五酸化バナジウム、メタバナジン酸、メタバナジン酸アンモニウム、オキシ三塩化バナジウム、三酸化バナジウム、二酸化バナジウム、バナジン酸マグネシウム、バナジルアセチルアセトネート、バナジウムアセチルアセトネートなどが挙げられる。特に４価のバナジウム化合物、または還元もしくは酸化することによって得られる４価のバナジウム化合物が望ましい。プライマー塗膜中に添加するバナジウム化合物は、化成処理皮膜に添加するバナジウム化合物と同種であっても異種であってもよい。バナジン酸化合物は、外部から侵入してくる水分に徐々に溶出するバナジン酸イオンと亜鉛系めっき鋼板表面のイオンが反応し、密着性の良い不働態皮膜を形成し、金属露出部を保護し防錆作用が現れると考えられている。 Vanadium compounds act as inhibitors. Examples of the vanadium compound include vanadium pentoxide, metavanadate, ammonium metavanadate, vanadium oxytrichloride, vanadium trioxide, vanadium dioxide, magnesium vanadate, vanadyl acetylacetonate, vanadium acetylacetonate, and the like. In particular, a tetravalent vanadium compound or a tetravalent vanadium compound obtained by reduction or oxidation is desirable. The vanadium compound added to the primer coating film may be the same as or different from the vanadium compound added to the chemical conversion coating. The vanadic acid compound reacts with the vanadate ions that gradually elute into the moisture entering from the outside and the ions on the surface of the galvanized steel sheet to form a passive film with good adhesion, thereby protecting and preventing the exposed metal part. It is thought that rust action appears.
　プライマー塗膜中のバナジウム化合物の含有量は、４～２０質量％であることが好ましい。４質量％未満ではインヒビター効果が低下して耐食性の低下を招き、２０質量％を超えるとプライマー塗膜の耐湿性の低下を招くからである。 The content of the vanadium compound in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the inhibitor effect is lowered and the corrosion resistance is lowered, and if it exceeds 20% by mass, the moisture resistance of the primer coating film is lowered.
　リン酸化合物はインヒビターとして作用し、例えばリン酸、リン酸のアンモニウム塩、リン酸のアルカリ金属塩、リン酸のアルカリ土類金属塩などが使用できる。特に、リン酸カルシウムなど、リン酸のアルカリ土類金属塩が好適である。 The phosphoric acid compound acts as an inhibitor. For example, phosphoric acid, ammonium salt of phosphoric acid, alkali metal salt of phosphoric acid, alkaline earth metal salt of phosphoric acid and the like can be used. In particular, alkaline earth metal salts of phosphoric acid such as calcium phosphate are suitable.
　プライマー塗膜中のリン酸化合物の含有量は、４～２０質量％であることが好ましい。４質量％未満ではインヒビター効果が低下して耐食性の低下を招き、２０質量％を超えるとプライマー塗膜の耐湿性の低下を招くからである。 The content of the phosphate compound in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the inhibitor effect is lowered and the corrosion resistance is lowered, and if it exceeds 20% by mass, the moisture resistance of the primer coating film is lowered.
　酸化マグネシウムは、初期の腐食によって生じた生成物を難溶性のマグネシウム塩として、安定化する効果がある。プライマー塗膜中の酸化マグネシウムの添加量は４～２０質量％であることが好ましい。４質量％未満では上記効果が低下して耐食性の低下を招き、２０質量％を超えるとプライマー塗膜の可撓性が低下することにより特に加工部の耐食性が低下することがあるからである。 Magnesium oxide has the effect of stabilizing the product produced by the initial corrosion as a sparingly soluble magnesium salt. The amount of magnesium oxide added in the primer coating is preferably 4 to 20% by mass. This is because if the amount is less than 4% by mass, the above-described effect is reduced, leading to a decrease in corrosion resistance. If the amount exceeds 20% by mass, the flexibility of the primer coating film is decreased, and in particular, the corrosion resistance of the processed part may be decreased.
　プライマー塗膜を形成する際に用いられる架橋剤は、ウレタン結合を有するポリエステル樹脂と反応して架橋塗膜を形成するものであり、ブロック化ポリイソシアネート化合物が好ましい。ブロック化ポリイソシアネートとしては、例えば、ポリイソシアネート化合物のイソシアネート基を、例えば、ブタノールなどのアルコール類、メチルエチルケトオキシムなどのオキシム類、ε－カプロラクタム類などのラクタム類、アセト酢酸ジエステルなどのジケトン類、イミダゾール、２－エチルイミダゾールなどのイミダゾール類、又はｍ－クレゾールなどのフェノール類などによりブロックしたものが挙げられる。 The crosslinking agent used in forming the primer coating film reacts with a polyester resin having a urethane bond to form a crosslinked coating film, and is preferably a blocked polyisocyanate compound. Examples of the blocked polyisocyanate include an isocyanate group of a polyisocyanate compound, for example, an alcohol such as butanol, an oxime such as methyl ethyl ketoxime, a lactam such as ε-caprolactam, a diketone such as acetoacetic acid diester, and an imidazole. And imidazoles such as 2-ethylimidazole, or those blocked with phenols such as m-cresol.
　プライマー塗膜の２５℃における破断伸びは２０％以上とする。これにより、各種用途に対し成形加工する際に発生するプライマー塗膜の変形によって、プライマー塗膜にクラックが発生することを抑制でき、加工部の耐食性が向上する。また、プライマー塗膜の２５℃における抗張力は２０ＭＰａ以上とする。２０ＭＰａ未満ではプライマー塗膜の強度が低下し、成形加工などでせん断力が作用した際、プライマー塗膜が剥離することがある。 The elongation at break of the primer coating at 25 ° C is 20% or more. Thereby, it can suppress that a primer coating film generate | occur | produces a crack by deformation | transformation of the primer coating film which generate | occur | produces at the time of shaping | molding with respect to various uses, and the corrosion resistance of a process part improves. The tensile strength of the primer coating at 25 ° C. is 20 MPa or more. If the pressure is less than 20 MPa, the strength of the primer coating film is lowered, and the primer coating film may be peeled off when a shearing force is applied during molding.
　プライマー塗膜の破断伸びと抗張力は以下のような方法で測定することができる。プライマー塗料をブリキ板上に硬化塗膜で約１０μｍになるように塗装し、最高到達温度が２３０℃になるように４０秒焼付硬化した塗膜をアマルガム法によってブリキ板から剥離して、フィルム状の試験用サンプルを作製する。次に、引張り試験機を用いて、２５℃、引張り速度４ｍｍ／分、チャック間距離４０ｍｍ、フルスケール設定２ｋｇの条件で引張り試験を５回行い、５回の試験で得られた伸び率の平均値を破断伸びとし、５回の試験で得られた引張り強度の平均値を抗張力とする。 The elongation at break and tensile strength of the primer coating can be measured by the following method. The primer coating is applied on the tinplate so that the cured coating has a thickness of about 10 μm, and the coating that has been baked and cured for 40 seconds so that the maximum temperature reaches 230 ° C. is peeled off from the tinplate by the amalgam method to form a film. Samples for testing are prepared. Next, using a tensile tester, a tensile test was performed 5 times under the conditions of 25 ° C., a tensile speed of 4 mm / min, a distance between chucks of 40 mm, and a full scale setting of 2 kg, and the average of the elongation obtained by the 5 tests The value is the elongation at break, and the average value of the tensile strength obtained in five tests is the tensile strength.
　プライマー塗膜の好ましい厚さは、１．５μｍ以上である。これより薄いと、耐食性の低下や、化成処理皮膜および上塗り塗膜との密着性の低下を招くからである。 The preferable thickness of the primer coating is 1.5 μm or more. If the thickness is smaller than this, the corrosion resistance is deteriorated, and the adhesion with the chemical conversion film and the top coat film is reduced.
　プライマー塗膜用樹脂組成物には、必要に応じて、塗料分野で通常使用されている公知の各種成分を含有させることができる。具体的には、例えば、レベリング剤、消泡剤などの各種表面調整剤、分散剤、沈降防止剤、紫外線吸収剤、光安定剤、シランカップリング剤、チタネートカップリング剤などの各種添加剤、着色顔料、体質顔料などの各種顔料、光輝材、硬化触媒、有機溶剤などが挙げられる。 The resin composition for the primer coating film can contain various known components that are usually used in the paint field, if necessary. Specifically, for example, various surface conditioners such as leveling agents and antifoaming agents, dispersants, anti-settling agents, ultraviolet absorbers, light stabilizers, silane coupling agents, various additives such as titanate coupling agents, Examples thereof include various pigments such as coloring pigments and extender pigments, glittering materials, curing catalysts, and organic solvents.
　プライマー塗膜を形成するための塗料組成物の塗装方法に特に制約はないが、好ましくは塗料組成物をロールコーター塗装、カーテンフロー塗装などの方法で塗布するのがよい。塗料組成物を塗装後、熱風加熱、赤外線加熱、誘導加熱などの加熱手段により焼き付け、プライマー塗膜を得る。焼付処理は、通常、最高到達板温を１８０～２７０℃程度とし、この温度範囲で約３０秒～３分行う。 Although there is no particular limitation on the coating method of the coating composition for forming the primer coating film, the coating composition is preferably applied by a method such as roll coater coating or curtain flow coating. After the coating composition is applied, it is baked by a heating means such as hot air heating, infrared heating, induction heating, etc. to obtain a primer coating film. The baking treatment is usually performed at a maximum plate temperature of about 180 to 270 ° C. and within this temperature range for about 30 seconds to 3 minutes.
　（上塗り塗膜）
　塗装亜鉛系めっき鋼板の製造においては、一般的に、プライマー塗膜上に上塗り塗料が塗装される。上塗り塗料を塗装することで、美観を付与することができ、また、塗装亜鉛系めっき鋼板として要求される加工性、耐候性、耐薬品性、耐汚染性、耐水性、耐食性などの各種性能を高めることができる。 (Top coat)
In the manufacture of a coated zinc-based plated steel sheet, generally, a top coating is applied on the primer coating film. By applying the top coating, it is possible to impart aesthetics and to provide various performances such as workability, weather resistance, chemical resistance, contamination resistance, water resistance, and corrosion resistance required for coated zinc-based plated steel sheets. Can be increased.
　本実施形態に使用する上塗り塗料として、例えば、ポリエステル樹脂系塗料、シリコンポリエステル樹脂系塗料、ポリウレタン樹脂系塗料、アクリル樹脂系塗料、フッ素樹脂系塗料などが挙げられる。 Examples of the top coating used in this embodiment include polyester resin-based paints, silicon polyester resin-based paints, polyurethane resin-based paints, acrylic resin-based paints, and fluororesin-based paints.
　上塗り塗膜の厚さは、５～３０μｍが好ましい。５μｍ未満では、色調外観を安定させることが困難であり、３０μｍを超えると、加工性の低下（上塗り塗膜のクラック発生）を招くからである。 The thickness of the top coat film is preferably 5 to 30 μm. If the thickness is less than 5 μm, it is difficult to stabilize the color appearance, and if it exceeds 30 μm, the workability deteriorates (cracking of the top coat film) is caused.
　上塗り塗膜には、目的、用途に応じて、酸化チタン、弁柄、マイカ、カーボンブラック、その他の各種着色顔料やアルミニウム粉やマイカなどのメタリック顔料、炭酸塩や硫酸塩などからなる体質顔料、あるいはシリカ微粒子、ナイロン樹脂ビーズ、アクリル樹脂ビーズなど各種微粒子、ｐ－トルエンスルホン酸、ジブチル錫ジラウレート等の硬化触媒、ワックスその他の添加剤を適量配合することができる。 Depending on the purpose and application, the top coat film has titanium oxide, petal, mica, carbon black, other various color pigments, metallic pigments such as aluminum powder and mica, extender pigments made of carbonates and sulfates, Alternatively, various fine particles such as silica fine particles, nylon resin beads and acrylic resin beads, curing catalysts such as p-toluenesulfonic acid and dibutyltin dilaurate, wax and other additives can be blended in appropriate amounts.
　上塗り塗膜を形成するための塗料組成物の塗装方法に特に制約はないが、好ましくは塗料組成物をロールコーター塗装、カーテンフロー塗装などの方法で塗布するのがよい。塗料組成物を塗装後、熱風加熱、赤外線加熱、誘導加熱などの加熱手段により焼き付け、上塗り塗膜を得る。焼付処理は、通常、最高到達板温を１８０～２７０℃程度とし、この温度範囲で約３０秒～３分行う。 There is no particular restriction on the coating method of the coating composition for forming the top coat film, but the coating composition is preferably applied by a method such as roll coater coating or curtain flow coating. After coating the coating composition, it is baked by a heating means such as hot air heating, infrared heating, induction heating, etc. to obtain a top coat film. The baking treatment is usually performed at a maximum plate temperature of about 180 to 270 ° C. and within this temperature range for about 30 seconds to 3 minutes.
　（亜鉛系めっき鋼板）
　表１に示す各試験例で使用した亜鉛系めっき鋼板は以下のとおりである。
１：板厚０．３５ｍｍのめっき付着量が片面あたり８０ｇ／ｍ２の溶融５５質量％アルミニウム－亜鉛合金めっき鋼板（JIS G3321、AZ150）
２：板厚０．３５ｍｍのめっき付着量が片面あたり１３０ｇ／ｍ２の溶融亜鉛―５％アルミニウム合金めっき鋼板（JIS G3317、Y25）
３：板厚０．３５ｍｍのめっき付着量が片面あたり１３０ｇ／ｍ２の溶融亜鉛めっき鋼板（JIS G3312、Z25） (Zinc-based plated steel sheet)
The galvanized steel sheets used in each test example shown in Table 1 are as follows.
1: Molten 55 mass% aluminum-zinc alloy plated steel sheet (JIS G3321, AZ150) with a plate thickness of 0.35 mm and a coating weight of 80 g / m 2 per side
2: Hot-dip zinc-5% aluminum alloy-plated steel sheet (JIS G3317, Y25) with a plate thickness of 0.35 mm and a coating weight of 130 g / m 2 per side
3: Hot dip galvanized steel sheet with a plate thickness of 0.35 mm and a coating weight of 130 g / m 2 per side (JIS G3312, Z25)
　各試験例において、表１に示す亜鉛系めっき鋼板の表面に、ロールコーターによって化成処理液を塗布し、乾燥することによって、表１に示す各種化成処理皮膜を形成した。その際、熱風乾燥炉を用いて到達板温９０℃で乾燥して化成処理皮膜を形成した。 In each test example, the chemical conversion treatment liquid shown in Table 1 was formed by applying the chemical conversion treatment liquid to the surface of the galvanized steel sheet shown in Table 1 using a roll coater and drying. At that time, it was dried at an ultimate plate temperature of 90 ° C. using a hot air drying furnace to form a chemical conversion treatment film.
　次いで、各試験例において、化成処理皮膜上にプライマー塗料をバーコーターで塗布し、鋼板の到達温度２３０℃、焼き付け時間３５秒で焼き付け、表１に示す各種プライマー塗膜を形成した。さらに、その上に表１に示す上塗り塗料組成物を表１に示す乾燥膜厚になるようにバーコーターで塗布し、鋼板の到達温度２３０℃～２６０℃、焼き付け時間４０秒で焼き付け、上塗り塗膜を形成した。このようにして、各種塗装亜鉛系めっき鋼板を得た。 Next, in each test example, a primer paint was applied onto the chemical conversion coating film with a bar coater, and baked at a steel plate reaching temperature of 230 ° C. for a baking time of 35 seconds to form various primer coating films shown in Table 1. Further, the top coating composition shown in Table 1 is applied with a bar coater so as to have the dry film thickness shown in Table 1, and the steel sheet is baked at a temperature of 230 ° C. to 260 ° C. for a baking time of 40 seconds. A film was formed. Thus, various coated galvanized steel sheets were obtained.
　（化成処理皮膜）
　化成処理皮膜における樹脂成分（Ａ）として、エステル結合を有するアニオンウレタン樹脂（a）としての第一工業製薬（株）製スーパーフレックス２１０と、ビスフェノール骨格を有するエポキシ樹脂（b）としての吉村油化学（株）製ユカレジンＲＥ－１０５０とを、樹脂の質量比で表１に示す質量比で混合したものを用いた。一方、比較として本発明外であるアクリル系樹脂（Ｂ）、ポリエステル系樹脂（Ｃ）を用いた。 (Chemical conversion coating)
As the resin component (A) in the chemical conversion film, Superflex 210 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as an anionic urethane resin (a) having an ester bond, and Yoshimura Oil Chemical as an epoxy resin (b) having a bisphenol skeleton A mixture of YUKARESIN RE-1050 manufactured by Co., Ltd. at a mass ratio shown in Table 1 was used. On the other hand, acrylic resin (B) and polyester resin (C), which are outside the present invention, were used for comparison.
　バナジウム化合物としては、アセチルアセトンでキレート化した有機バナジウム化合物を用い、ジルコニウム化合物としては、炭酸ジルコニウムアンモニウムを用い、フッ素化合物としては、フッ化アンモニウムを用いた。 An organic vanadium compound chelated with acetylacetone was used as the vanadium compound, ammonium zirconium carbonate was used as the zirconium compound, and ammonium fluoride was used as the fluorine compound.
　これらの原料を混合して化成処理液を得た。化成処理液のｐＨは８～１０とした。化成処理皮膜中の各成分の含有量は表１に示すとおりとした。ただし、比較例１３，１４では、亜鉛系めっき鋼板にクロメート系化成処理（シリカ含有塗布型クロメート）を施した。 These raw materials were mixed to obtain a chemical conversion treatment liquid. The pH of the chemical conversion treatment solution was 8-10. The content of each component in the chemical conversion film was as shown in Table 1. However, in Comparative Examples 13 and 14, the chromate-based chemical conversion treatment (silica-containing coating chromate) was applied to the zinc-based plated steel sheet.
　（プライマー塗膜）
　プライマー塗膜を形成するための塗料は、以下の方法で作製した。
　主成分であるウレタン結合を有するポリエステル樹脂（α）として、ウレタン変性ポリエステル樹脂をブロック化イソシアネートで硬化させたものを用いた。ウレタン変性ポリエステル樹脂は、ポリエステル樹脂４５５質量部、イソホロンジイソシアネート４５質量部を反応させて得た。ウレタン変性ポリエステル樹脂の樹脂酸価は３、数平均分子量は５，６００、水酸基価は３６であった。 (Primer coating)
The coating material for forming the primer coating film was produced by the following method.
As a polyester resin (α) having a urethane bond as a main component, a urethane-modified polyester resin cured with blocked isocyanate was used. The urethane-modified polyester resin was obtained by reacting 455 parts by mass of a polyester resin and 45 parts by mass of isophorone diisocyanate. The resin acid value of the urethane-modified polyester resin was 3, the number average molecular weight was 5,600, and the hydroxyl value was 36.
　なお、上記ウレタン変性ポリエステル樹脂を製造する際に用いたポリエステル樹脂は、次にように製造した。攪拌機、精留塔、水分離器、冷却管及び温度計を備えたフラスコに、イソフタル酸３２０質量部、アジピン酸２００質量部、トリメチロールプロパン６０質量部、シクロヘキサンジメタンノール４２０質量部を仕込み、加熱、攪拌し、生成する縮合水を系外へ留去させながら、１６０℃から２３０℃まで一定速度で４時間かけて昇温させた。温度２３０℃に昇温したとき、キシレン２０質量部を徐々に添加し、温度を２３０℃に維持して縮合反応を続けた。酸価が５以下になった時に反応を終了し、１００℃に冷却後、ソルベッソ１００（エクソンモービル社製、商品名、高沸点芳香族炭化水素系溶剤）１２０質量部、ブチルセロソルブ１００質量部を加え、ポリエステル樹脂の溶液を得た。 In addition, the polyester resin used when manufacturing the said urethane-modified polyester resin was manufactured as follows. A flask equipped with a stirrer, a rectifying column, a water separator, a condenser and a thermometer was charged with 320 parts by mass of isophthalic acid, 200 parts by mass of adipic acid, 60 parts by mass of trimethylolpropane, and 420 parts by mass of cyclohexanedimethanol. The mixture was heated and stirred, and the temperature was raised from 160 ° C. to 230 ° C. at a constant rate over 4 hours while distilling out the generated condensed water to the outside of the system. When the temperature was raised to 230 ° C., 20 parts by mass of xylene was gradually added, and the condensation reaction was continued while maintaining the temperature at 230 ° C. The reaction was terminated when the acid value became 5 or less, and after cooling to 100 ° C., 120 parts by mass of Solvesso 100 (product name, high-boiling aromatic hydrocarbon solvent, manufactured by ExxonMobil) and 100 parts by mass of butyl cellosolve were added. A polyester resin solution was obtained.
　一方、比較として、破断伸びを本発明外とするウレタン硬化ポリエステル樹脂（β）、本発明外の樹脂であるメラミン硬化ポリエステル樹脂（γ）およびウレタン硬化エポキシ樹脂（δ）を用いた。 On the other hand, as a comparison, urethane cured polyester resin (β) whose elongation at break was outside the present invention, melamine cured polyester resin (γ) and urethane cured epoxy resin (δ), which were resins outside the present invention, were used.
　バナジウム化合物としてはバナジン酸マグネシウムを用い、リン酸化合物としてはリン酸カルシウムを用いた。 As the vanadium compound, magnesium vanadate was used, and as the phosphate compound, calcium phosphate was used.
　これらの原材料を混合後ボールミルで約１時間攪拌してプライマー塗料を得た。プライマー塗膜中の各成分の含有量は表１に示すとおりとした。ただし、比較例１３，１４では、クロム酸ストロンチウム２５質量％含有するウレタン硬化エポキシ樹脂系プライマー塗膜を用いた。 After mixing these raw materials, a primer coating was obtained by stirring for about 1 hour in a ball mill. The content of each component in the primer coating was as shown in Table 1. However, in Comparative Examples 13 and 14, a urethane-cured epoxy resin primer coating film containing 25% by mass of strontium chromate was used.
　各試験例において、プライマー塗膜を２５℃での破断伸び及び抗張力を既述の方法で測定した。結果を表１に示す。 In each test example, the elongation at break and tensile strength of the primer coating film at 25 ° C. were measured by the methods described above. The results are shown in Table 1.
　（上塗り塗膜）
　表１に示す上塗り塗膜用の樹脂は以下のとおりである。
Ｉ：メラミン硬化ポリエステル塗料「プレカラーＨＤ００３０ＨＲ」（BASFジャパン株製）
ＩＩ：ポリフッ化ビニリデンとアクリル樹脂が質量比で８０：２０であるオルガノゾル系焼付け型フッ素樹脂系塗料「プレカラーNo.8800ＨＲ」（BASFジャパン株製） (Top coat)
Resins for the top coat film shown in Table 1 are as follows.
I: Melamine cured polyester paint “Precolor HD0030HR” (BASF Japan Ltd.)
II: Organosol-based baking type fluororesin paint “Precolor No. 8800HR” (made by BASF Japan Ltd.) in which polyvinylidene fluoride and acrylic resin are in a mass ratio of 80:20
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記の本発明例及び比較例の塗装亜鉛系めっき鋼板について、以下に示す評価方法により、耐食性、曲げ加工部における密着性、耐スクラッチ密着性を評価した。その結果を、表２に示す。 The corrosion resistance, the adhesion in the bent portion, and the scratch resistance were evaluated for the coated zinc-based plated steel sheets of the present invention examples and comparative examples by the following evaluation methods. The results are shown in Table 2.
　（１）耐食性
　複合サイクル腐食試験（JIS H8502 8.1）に準じて１２０サイクル（合計960時間）の試験を行った。 (1) Corrosion resistance 120 cycles (total 960 hours) were tested according to the combined cycle corrosion test (JIS H8502 8.1).
　（１－１）曲げ加工部の耐食性
　６Ｔ（試験片と同一の板を内側に６枚挟み込み１８０度密着曲げを実施）の曲げ加工部において、試験後の表面観察を行い、下記基準に従い、上塗り塗膜の膨れあるいは白錆の発生面積率で評価した。
◎：膨れおよび錆の発生が認められない
○：膨れおよび／または錆の発生が合計で１０％以下認められる
△：膨れおよび／または錆の発生が合計で１０％超５０％以下認められる
×：膨れおよび／または錆の発生が合計で５０％超認められる (1-1) Corrosion resistance of the bent portion The surface after the test is observed at the bent portion of 6T (6 sheets of the same specimen as the test piece are sandwiched inside and 180 degree contact bending is performed), and the top coat is applied according to the following criteria Evaluation was based on the area ratio of occurrence of blistering or white rust.
A: No occurrence of blistering and rust B: Blowing and / or rusting is observed in a total of 10% or less. B: Bulging and / or rusting is observed in a total of more than 10% and 50% or less. More than 50% of blisters and / or rust is observed
　（１－２）切断端面の耐食性
　切断時のバリが上になっている端面（いわゆる上バリ）において、膨れまたは白錆の最大発生幅を測定し、下記基準で評価した。
◎：３ｍｍ未満
○：３ｍｍ以上、５ｍｍ未満
△：５ｍｍ以上、１０ｍｍ未満
×：１０ｍｍ以上 (1-2) Corrosion resistance of the cut end face The maximum occurrence width of blisters or white rust was measured on the end face where the burrs at the time of cutting (so-called upper burrs) were up, and evaluated according to the following criteria.
◎: Less than 3 mm ○: 3 mm or more, less than 5 mm Δ: 5 mm or more, less than 10 mm x: 10 mm or more
（２）曲げ加工部における密着性
　２Ｔ曲げ（試験片と同じ板を２枚はさんだ状態で１８０°の密着曲げ）を行った部分をセロハンテープ（ニチバン製）により強制的に塗膜剥離試験を行った。評価は塗膜の剥離面積により評価した。
○：剥離なし
△：剥離面積１０％未満
×：剥離面積１０％以上 (2) Adhesiveness at the bending portion The part subjected to 2T bending (180 ° close contact bending with the same plate as the test piece sandwiched) is forcibly subjected to the coating film peeling test using cellophane tape (manufactured by Nichiban). went. Evaluation was based on the peeled area of the coating film.
○: No peeling Δ: Peeling area less than 10% ×: Peeling area 10% or more
（３）耐スクラッチ密着性
　１０円硬貨の外周部で塗膜を一定の方向に引っかき、塗膜の剥離状態を、下記基準にしたがい評価した。
○：上塗り塗膜とプライマー塗膜の界面、プライマー塗膜と化成処理皮膜の界面、または、化成処理皮膜とめっき界面で剥離なし
×：上塗り塗膜とプライマー塗膜の界面、プライマー塗膜と化成処理皮膜の界面、または、化成処理皮膜とめっきの界面のいずれかで剥離あり (3) Scratch resistance adhesion The coating film was scratched in a certain direction at the outer periphery of a 10-yen coin, and the peeling state of the coating film was evaluated according to the following criteria.
○: No peeling at the interface between the top coating film and the primer coating film, at the interface between the primer coating film and the chemical conversion coating film, or at the chemical conversion coating film and the plating interface ×: The interface between the top coating film and the primer coating film, the primer coating film and the chemical conversion There is peeling at either the interface of the treated film or the interface between the chemical conversion film and the plating
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　本発明の塗装亜鉛系めっき鋼板は、例えば屋根・壁・シャッターなどの建材内外装材のほか、エアコン室外機などの家電製品などの用途に好適である。 The coated galvanized steel sheet of the present invention is suitable for applications such as interior / exterior materials for building materials such as roofs, walls, and shutters, and home appliances such as air conditioner outdoor units.

Claims (3)

  1. 　亜鉛系めっき鋼板と、
    　該亜鉛系めっき鋼板の少なくとも片面に形成された、クロメート系化合物を含有しない化成処理皮膜と、
    　該化成処理皮膜上に形成された、クロメート系化合物を含有しないプライマー塗膜と、
    　該プライマー塗膜上に形成された上塗り塗膜と、
    を有する塗装亜鉛系めっき鋼板であって、
    　前記化成処理皮膜が樹脂成分と無機成分の複合体であり、前記樹脂成分として、エステル結合を有するアニオンウレタン樹脂（a）、およびビスフェノール骨格を有するエポキシ樹脂（b）を合計で３０～５０質量％含有し、前記（a）と前記（b）の配合比率が、質量％で３：９７～６０：４０の範囲内であり、前記無機成分として、バナジウム化合物を２～１０質量％、ジルコニウム化合物を４０～６０質量％、およびフッ素化合物を０．５～５質量％含有し、
    　前記プライマー塗膜がウレタン結合を有するポリエステル樹脂を主成分とし、バナジウム化合物、リン酸化合物、および酸化マグネシウムを含有し、前記プライマー塗膜の、２５℃における破断伸びが２０％以上であり、かつ２５℃における抗張力が２０ＭＰａ以上である
    ことを特徴とする塗装亜鉛系めっき鋼板。     Galvanized steel sheet,
    A chemical conversion treatment film not containing a chromate compound formed on at least one surface of the galvanized steel sheet;
    A primer coating film formed on the chemical conversion coating film and containing no chromate compound;
    A top coat film formed on the primer coat film;
    A coated galvanized steel sheet having
    The chemical conversion film is a composite of a resin component and an inorganic component, and as the resin component, an anionic urethane resin (a) having an ester bond and an epoxy resin (b) having a bisphenol skeleton in total 30 to 50% by mass And the blending ratio of (a) and (b) is in the range of 3:97 to 60:40 by mass%, and the inorganic component is 2 to 10 mass% of vanadium compound and zirconium compound. 40 to 60% by mass, and 0.5 to 5% by mass of a fluorine compound,
    The primer coating film contains a polyester resin having a urethane bond as a main component, contains a vanadium compound, a phosphoric acid compound, and magnesium oxide, and the elongation at break at 25 ° C. of the primer coating film is 20% or more, and 25 A coated galvanized steel sheet having a tensile strength at 20 ° C. of 20 MPa or more.
  2. 　前記プライマー塗膜中に、前記ポリエステル樹脂が４０～８８質量％、前記バナジウム化合物が４～２０質量％、前記リン酸化合物が４～２０質量％、前記酸化マグネシウムが４～２０質量％含有される請求項１に記載の塗装亜鉛系めっき鋼板。 The primer coating contains 40 to 88% by mass of the polyester resin, 4 to 20% by mass of the vanadium compound, 4 to 20% by mass of the phosphoric acid compound, and 4 to 20% by mass of the magnesium oxide. The coated zinc-based plated steel sheet according to claim 1.
  3. 　前記化成処理皮膜の付着量が０．０２５～０．５ｇ／ｍ２、前記プライマー塗膜の厚さが１．５μｍ以上である請求項１または２に記載の塗装亜鉛系めっき鋼板。 The coated zinc-based plated steel sheet according to claim 1 or 2, wherein the chemical conversion coating has an adhesion amount of 0.025 to 0.5 g / m 2 and the primer coating has a thickness of 1.5 µm or more.
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