JP2010075859A - Automobile members - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automobile member which can be produced in an existing process, and which is environmentally considered and extremely excellent in corrosion resistance even if the film thickness of an electrodeposition coating is half or less of the film thickness that was conventionally required. <P>SOLUTION: The automobile member has an organic coating film (A) containing a conductive particle (&alpha;) and a rust prevention pigment (&beta;) on at least one face of a metallic material, and an electrodeposition coating film (B) formed from the electrodeposition coating which does not substantially contain lead on the upper layer of the organic coating film (A). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an automobile member (including a repair member for replacement) that is extremely excellent in corrosion resistance of not only a flat portion but also a scratched portion, an end surface portion, and a processed portion.

  Automobile parts are made of metal materials such as steel plates, and are (i) blanking, (ii) press working, (iii) assembly / joining, (iv) cleaning, (v) chemical conversion treatment, (vi) electrodeposition coating In general, the members manufactured through the process and used on the outer surface are further subjected to coating such as intermediate coating or top coating. The corrosion resistance of automobile parts is often ensured by the electrodeposition coating after the chemical conversion treatment, but the electrodeposition coating around the inner part of the bag-shaped part or the folded hem part is not Unfortunately, it is difficult to ensure a sufficient film thickness for electrodeposition coating. Therefore, the corrosion resistance is supplemented by the application of rust prevention auxiliary materials such as sealers, adhesives, and waxes. In addition, in order to ensure the corrosion resistance of automobile parts having a severe corrosive environment, various rust prevention auxiliary materials such as waterproof sheets are currently used. Needless to say, these rust-proof secondary materials are factors that increase automobile manufacturing costs, but also reduce productivity and increase vehicle weight, so corrosion resistance is ensured even if these secondary materials are reduced. There is a strong demand for an automobile member that can ensure corrosion resistance even if the film thickness of electrodeposition coating cannot be obtained sufficiently.

  Conventionally, as a rust prevention measure for automobile members, research and development for improving the corrosion resistance of a metal material as a raw material has been actively conducted. For example, Patent Document 1 discloses a technique for forming a coating film containing zinc (Zn) on the surface of a metal material. However, such a Zn-containing coating film has a problem that remarkable coating film peeling occurs at the time of press molding, and the corrosion resistance of the portion where the coating film has peeled is lowered.

  In contrast to such a coated metal material, Patent Literature 2 and Patent Literature 3 disclose a surface-treated steel sheet having a thin film coating that does not contain a conductive pigment such as Zn. However, these coatings of thin films did not show a significant improvement in corrosion resistance, and ensured corrosion resistance on the premise of ensuring the film thickness of electrodeposition coating and applying anticorrosive auxiliary materials.

  On the other hand, recently, paint metal materials have been developed for the purpose of omitting the chemical conversion treatment and the electrodeposition coating process. For example, Patent Document 4 and Patent Document 5 disclose a coated metal material containing a conductive pigment, but it cannot ensure high corrosion resistance until electrodeposition coating can be omitted, and has not been put into practical use. .

  By the way, in response to the recent trend of environmental measures, a lead-free electrodeposition coating material substantially free of lead, which has been used as a conventional anticorrosive pigment having a high corrosion resistance function as disclosed in Patent Document 6, has been developed. Has been put to practical use. As described above, there is a concern that the corrosion resistance cannot be sufficiently ensured by the electrodeposition coating which does not substantially contain a lead compound having a high rust prevention ability. In particular, there is a concern that the corrosion resistance of the scratched part, the end face part, and the processed part due to the anticorrosive pigment and the corrosion resistance of the thin film are lowered.

JP-A-55-17508 Japanese Patent Publication No. 4-48348 Japanese Patent Laid-Open No. 2-15177 JP-A-10-128906 JP 2000-70842 A JP 2005-194390 A

  In view of the present situation, the present invention can be manufactured by an existing process, is environmentally friendly, and has extremely excellent corrosion resistance (planar portion) even when the electrodeposition coating film thickness is less than half of the conventionally required film thickness. It is an object to provide an automobile member having not only a scratched part, an end face part, and a processed part. That is, an object of the present invention is to provide an automobile member having an extremely excellent corrosion resistance even when a coating metal material that can be joined by press working and welding is used as a raw material and coating with an electrodeposition coating material that does not substantially contain lead is used as a thin film. It is what.

The main point of the present invention is that
(1) It has an organic coating film (A) containing conductive particles (α) and an antirust pigment (β) on at least one side of a metal material, and lead is not substantially contained in the upper layer of the organic coating film. An automobile member characterized by having an electrodeposition coating (B) formed from an electrodeposition coating;
(2) The automobile member according to (1), further comprising one or more coating films on the upper layer of the automobile member,
(3) When T _A is the thickness of the organic coating film (A) and T _B is the thickness of the electrodeposition coating film (B), T _A ≧ 2 μm, T _B ≧ 3 μm, T _A + T _B ≧ The automobile member according to (1) or (2), characterized by satisfying 8 μm,
(4) the collector, wherein the minimum value of the thickness T _B of the coating film (B) is 10μm or less, an automobile member according to any one of (1) to (3),
(5) The automobile member according to any one of (1) to (4), wherein the conductive particles (α) contain ferrosilicon.
(6) The automobile member according to (5), wherein the content of Si contained in the ferrosilicon is 70% by mass or more,
(7) The content of the conductive particles (α) contained in the organic coating film (A) is 15 to 60% by volume, according to any one of (1) to (6), Automotive parts,
(8) The automobile member according to any one of (1) to (7), wherein the rust preventive pigment (β) does not contain chromium,
(9) The rust preventive pigment (β) contains a compound capable of releasing at least one of silicate ions, phosphate ions, and vanadate ions, according to any one of (1) to (8), Automotive parts as described,
(10) The content of the anticorrosive pigment (β) contained in the organic coating film (A) is 2 to 25% by volume, according to any one of (1) to (9), Automotive parts,
(11) The automobile member according to any one of (1) to (10), wherein the binder component in the organic coating film (A) contains a resin containing a urethane bond,
(12) The automobile member according to any one of (1) to (11), wherein the metal material is a zinc-based or aluminum-based plated steel plate.

  Since the automobile member of the present invention is extremely excellent in corrosion resistance, it can be expected to improve reliability by applying it to a member having a severe corrosive environment or a member having poor adhesion property of electrodeposition coating. Furthermore, it can be expected to reduce various rust-preventing auxiliary materials that are the cause of an increase in automobile manufacturing cost, a decrease in productivity, and an increase in the weight of the vehicle body. In addition, it can be manufactured by an existing process, and further, since it does not substantially contain lead, it is also promising as an environmentally friendly member, and its contribution to the automobile field is very large.

  The present invention relates to an automobile member (including a repair member for replacement) that is extremely excellent in corrosion resistance of not only a flat portion but also a scratched portion, an end surface portion, and a processed portion. More specifically, the present invention provides an automobile member that is extremely excellent in corrosion resistance, in which a metal material having an organic coating film is subjected to electrodeposition coating after being pressed and joined, and in some cases, an intermediate layer or a top coat is further coated thereon.

  Painted metal materials used as materials for automobile members are joined by press molding and welding before electrodeposition coating. Therefore, it is necessary to add conductive particles in the organic coating film so that welding can be performed. In addition, by adding conductive particles in the organic coating film to ensure conductivity, an electrodeposition coating film can be formed on the upper layer of the organic coating film. That is, the conductive particles must be added to ensure weldability and electrodeposition coating properties. However, the addition of the conductive particles makes the organic coating film brittle, so that the coating film is likely to be cracked or scratched during press molding, which may become a starting point of corrosion and decrease the corrosion resistance. In addition, since the organic coating film cannot be obtained at the cut end face part or the welded part, it is very difficult to prevent rust at those places. In order to ensure these rust preventions, it is preferable to add a rust prevention pigment having a self-repair function to the coating film. However, even if these anticorrosive pigments are applied to organic coatings that have become brittle due to the addition of conductive particles, cracks and scratches occur in the coatings during press molding. The active ingredient in the rust pigment flows out, and the sustainability of the effect cannot be expected. For this reason, even if a rust preventive pigment is added to an organic coating film containing conductive particles, only the conductive particles remain in the processed part and the like, so it is difficult to ensure long-term corrosion resistance. .

  On the other hand, since the electrodeposition coating is applied after press molding and welding, the cut end face portion and the welded portion can be covered to some extent with the electrodeposition coating. Although the rust preventive pigment is contained in the electrodeposition coating film, the effect is not great. For this reason, an electrodeposition coating film that ensures corrosion resistance mainly by relying on the barrier properties of the coating film cannot provide sufficient corrosion resistance unless the coating film thickness can be secured. In addition, even if the film thickness is sufficient, the self-repair function of the anticorrosive pigment is low, so that if the electrodeposition coating film has a defective part such as a scratch, corrosion rapidly proceeds from that part. The trend is remarkable due to the recent lead-free.

  Therefore, as a result of intensive studies to solve the above-mentioned problems, the present inventors designed an organic coating film applied to a metal material used as a material as a rust-proof coating film with an emphasis on the self-repair function, as described below. And it discovered that the corrosion resistance which was excellent by the composite effect can be ensured by giving the electrodeposition coating film which has barrier property to the upper layer. That is, it was found that the organic coating film having a self-repairing function can ensure the corrosion resistance of the scratched part, the end face part, and the processed part, and the function can be maintained over a long period of time by the upper electrodeposition coating film. The corrosion resistance including not only the flat part but also the scratched part, the end face part and the processed part was successfully maintained for a long time.

  When using these organic coatings and electrodeposition coatings on coated metal materials in a single layer, there are the above-mentioned problems, but combining these coatings can ensure very good corrosion resistance. it can. That is, by making the organic coating film containing a rust preventive pigment having a self-repairing function as a lower layer, and making the electrodeposition coating film having a barrier effect an upper layer, the durability of the rust preventive pigment in the lower layer coating film is improved. Long-term corrosion resistance can be ensured. In addition, the electrodeposition coating also enters the defective part of the organic coating produced by pressing and repairs the defective part, and the organic coating such as the cut end face and welded part is not covered The electrodeposition coating covers and barriers the effect of compensating the weakness of the lower layer organic coating by the upper layer coating, and conversely the coating defects of the electrodeposition coating and scratches caused after coating The effect of repairing the anticorrosive pigment contained in the underlying organic coating can also be expected.

  In addition, since the electrodeposition coating film of the present invention is mainly intended to retain the anticorrosive pigment of the lower organic coating film rather than the barrier effect against the corrosion factor, as long as the organic coating film is covered to some extent, Even a thin film having a thickness of 10 μm or less, which cannot be expected to have a barrier effect against a corrosion factor, can sufficiently secure long-term corrosion resistance.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The automobile member of the present invention has an organic coating film (A) containing conductive particles (α) and a rust preventive pigment (β) on at least one surface of a metal material, and an electric layer substantially free of lead in the upper layer. It has the electrodeposition coating film (B) formed from a coating material.

  Although there is no particular limitation on the method for producing an automobile member of the present invention, a metal material having the organic coating film (A) on at least one side is used as a raw material, and (i) blanking, (ii) press working, (iii) assembly / Generally, it is manufactured through steps of bonding, (iv) cleaning, (v) chemical conversion treatment, and (vi) electrodeposition coating.

  The (v) chemical conversion treatment step is a step of forming a chemical conversion treatment film on the surface of the metal material for the purpose of improving the adhesion between the metal material and the electrodeposition coating film. In the part which has the organic coating film (A) on the surface of the metal material in the automobile member of the present invention, due to the effect of the organic coating film (A), good adhesion with the electrodeposition coating film is obtained even without the chemical conversion coating film. It can be secured. Therefore, when the organic coating film (A) is coated on both surfaces of the metal material, the chemical conversion treatment step can be omitted. Moreover, even if the metal plate having the organic coating film (A) undergoes a chemical conversion treatment step, the chemical conversion coating film hardly adheres to the organic coating film (A), but even if it is temporarily attached, the purpose of the present invention is impaired. is not.

  The metal material used in the present invention is not particularly limited. For example, various metals such as steel, aluminum, copper, and titanium, or alloy materials (plate material, pipe material, wire material, shape material, etc., and , Molded or joined them), and metal materials plated with any metal or alloy such as zinc, aluminum, nickel, chromium, copper, cobalt, silicon, iron, magnesium, calcium, manganese, etc. Can be used. Among these, steel plates, plated steel plates, and aluminum plates are preferable as metal materials used in the present invention, and zinc-based plated steel plates and aluminum-based plated steel plates are more preferable.

Zinc-coated steel sheets include galvanized steel sheets, zinc-nickel plated steel sheets, zinc-iron plated steel sheets, zinc-chromium plated steel sheets, zinc-aluminum plated steel sheets, zinc-titanium plated steel sheets, zinc-magnesium plated steel sheets, zinc-manganese. Galvanized steel sheets such as plated steel sheets, zinc-aluminum-magnesium plated steel sheets, zinc-aluminum-magnesium-silicon-plated steel sheets, and cobalt, molybdenum, tungsten, nickel as a small amount of different metal elements or impurities in these plated layers Examples include those containing titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium, arsenic, etc., and those in which inorganic substances such as silica, alumina, titania, etc. are dispersed.
Examples of the aluminum-based plated steel sheet include aluminum or an alloy composed of aluminum and at least one of silicon, zinc, and magnesium, such as an aluminum-silicon plated steel sheet, an aluminum-zinc plated steel sheet, and an aluminum-silicon-magnesium plated steel sheet. . Furthermore, the present invention can also be applied to multilayer plating in combination with the above plating and other types of plating such as iron plating, iron-phosphorus plating, nickel plating, cobalt plating and the like. The plating method is not particularly limited, and any known method such as an electroplating method, a hot dipping method, a vapor deposition plating method, a dispersion plating method, and a vacuum plating method may be used.

  The organic coating film (A) used in the present invention is not particularly limited as long as it contains conductive particles (α) and a rust preventive pigment (β). The thing in which well-known electroconductive particle and the antirust pigment were disperse | distributed in the binder can be used. These will be described in detail later.

  The electrodeposition coating film (B) used for this invention will not be specifically limited if it is formed from the electrodeposition coating material which does not contain lead (including the lead in a lead compound) substantially. The phrase “substantially free” as used herein means that lead is not contained in an amount that adversely affects the environment. Specifically, the amount of lead contained in the electrodeposition paint is 10 ppm. It means the following.

  Electrodeposition coatings generally immerse the object in a paint tank filled with a water-soluble or water-dispersible electrodeposition paint, and apply a DC voltage between the electrodes separately provided in the tank. By this, it forms by the coating system which deposits a coating-film formation component on the to-be-coated object surface. That is, the object to be coated in the present invention is a metal plate having an organic coating film (A) containing conductive particles (α) and a rust preventive pigment (β) on at least one side, and the molded product or the molded product is welded. Etc., and members joined by, for example. Electrodeposition paints include cation-type electrodeposition paints with positively charged film forming components and anion-type electrodeposition paints with negative charge. The electrodeposition paints used in the present invention are cationic from the viewpoint of corrosion resistance. A type electrodeposition paint is preferred. As a base resin for forming an electrodeposition coating film, for example, a polyamine resin in which a bisphenol A type epoxy resin is plastically modified with polyether, polyester, polyamide, etc., and a large number of amino groups are introduced into the molecule with an amino compound. Although what neutralized with low molecular organic acids, such as an acetic acid, and disperse | distributed to water can be used, it does not specifically limit. Alcohol blocks of polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI) are mainly used as the curing agent. In some cases, it is used in a simple mixture, and the amount used is generally about 20 to 30% of the total resin solids. Water-soluble resins and surfactants can also be used as dispersion stabilizers for base resins and pigments. Solvents such as water-soluble alcohols and ketones are used to stabilize resin dispersion and adjust electrodeposition coating properties. Can also be used. As the catalyst, tin ions, cerium ions, bismuth ions, copper ions, zinc ions, and the like can also be used.

  The electrodeposition coating film (B) used in the present invention may contain a color pigment, a rust preventive pigment, and an extender pigment as necessary. For example, pigments such as carbon black, extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica, clay, and silica, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, phosphorous acid Zinc, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate, and rust preventive pigments such as aluminum phosphomolybdate and aluminum phosphomolybdate can be used. .

  The automobile member of the present invention can be further coated as required after electrodeposition coating. For example, in order to satisfy the design properties, durability, chipping resistance, and the like required on the outer surface side of an automobile, it is possible to apply a known intermediate coating or top coating. If necessary, it is possible to further apply a clear guard coating on the upper layer.

The organic coating of automobile parts of the present invention (A), at the site where the electrodeposition coating film (B) are sequentially formed, the thickness of the organic coating film (A) and T _A, the electrodeposition coating the thickness of (B) is taken as T _B, by securing the T _a or 1 [mu] m, although the corrosion resistance improving effect of the prior art can be confirmed, in order to obtain a stable effect is preferably at least 2 [mu] m. In addition, although it is not necessary to prescribe | regulate a film thickness upper limit from a corrosion-resistant viewpoint, it is preferable to set it as 10 micrometers or less from viewpoints, such as ensuring stable electrodeposition coating property, weldability, and coating cost. Although for the T _B can confirm the corrosion resistance improvement effect over the prior art in that the securing or 2 [mu] m, in order to obtain a stable effect is preferably at least 3 [mu] m. In addition, although there is no upper limit of the film thickness from the viewpoint of corrosion resistance, the effect of improving the performance cannot be expected even if it exceeds 20 μm, and therefore it is preferably 20 μm or less from the viewpoint of paint cost, power cost, productivity, and the like. However, the film thickness of the electrodeposition coating film varies widely even with the same member depending on the shape of the object to be coated, the distance from the electrode, the properties of the paint, etc. It is difficult to eliminate the excessive amount, and since there is no adverse effect on the performance due to the thick film thickness, it is not always necessary that the film thickness of the entire surface of the automobile member be 20 μm or less, and a partially abnormal film The occurrence of thick parts is not particularly a problem.

In order to ensure more stable corrosion resistance, it is preferable that all parts satisfy T _A ≧ 2 μm, T _B ≧ 3 μm, and T _A + T _B ≧ 8 μm. If T _A is less than 2 μm, T _B is less than 3 μm, and T _A + T _B is less than 8 μm, sufficient corrosion resistance may not be obtained. More preferable lower limit conditions of the film thickness are T _A ≧ 3 μm, T _B ≧ 5 μm, and T _A + T _B ≧ 10 μm.

Automobile parts of the present invention, the organic coating film (A), at the site where the electrodeposition coating film (B) are sequentially formed, is the thinnest portion of the thickness T _B of the electrodeposition coating film (B) Even when the thickness is 10 μm or less, corrosion resistance equal to or higher than that of a conventional automobile member can be ensured. At present, the electrodeposition coating is usually used in a thickness of about 10 to 25 μm. In a conventional automobile member, when the thickness of the electrodeposition coating film is less than 10 μm, the corrosion resistance is extremely lowered, so that it is necessary to secure 10 μm or more, and it is necessary to secure a thickness of about 20 μm. For this reason, in order to secure the electrodeposition coating thickness of the part where the electrodeposition coating is poor, measures such as increasing the coating thickness of the entire member have been taken, leading to a decrease in productivity and economy. Automobile parts of the present invention, the electrodeposition coating the film thickness T _B of the thinnest portion of (B) is not more 10μm or less, 2 [mu] m or more, preferably 3μm or more, sufficient if more preferably 5μm or more Since corrosion resistance can be obtained, the present invention is particularly effective when applied to an automobile member including a portion where the electrodeposition coating is poor.

  The thickness of the organic coating film (A) and the electrodeposition coating film (B) can be measured by observing a cross section of a metal material having each coating film or using an electromagnetic film thickness meter. In addition, the mass of the coating film adhered per unit area may be calculated by dividing by the specific gravity of the coating film or the specific gravity after drying of the coating material. The adhesion mass of the coating is the mass difference before and after coating, the mass difference before and after peeling the coating after coating, or the presence of an element whose content in the coating is known in advance by fluorescent X-ray analysis. What is necessary is just to select appropriately from the existing methods, such as measuring quantity. The specific gravity of the paint film or the specific gravity after drying of the paint is measured by measuring the volume and mass of the isolated paint film, measuring the volume and mass after taking an appropriate amount of paint in a container and drying it, or What is necessary is just to select suitably from the existing method, such as calculating from a compounding quantity and the known specific gravity of each component.

  Next, the organic coating film (A) containing the conductive particles (α) and the rust preventive pigment (β) of the present invention will be described in more detail. In addition, a case where a base treatment is applied between the organic coating film (A) and the metal material will be described.

  The organic coating film (A) of the present invention contains a binder component for holding the coating film. Although there is no restriction | limiting in particular in the binder component, It is suitable to use an organic resin. The organic resin is not particularly limited. For example, urethane resin, epoxy resin, acrylic resin, polyester resin, fluorine resin, silicon resin, polyolefin resin, butyral resin, ether resin, sulfone resin, polyamide resin, polyimide resin, amino resin, Examples thereof include resins such as phenol resins, vinyl chloride resins, polyvinyl alcohol resins, isocyanate resins, copolymer resins thereof, mixtures thereof, composites, and the like. What is necessary is just to select from well-known techniques, such as what is hardened and dried at normal temperature, what is hardened and dried with heat, what is hardened and dried with energy rays such as ultraviolet rays and electron beams. In addition, a coated metal plate can be produced by laminating films containing these resins as main components.

  Among these, particularly when a resin containing a urethane bond is used in the coating film, the corrosion resistance, workability, and conductivity can be arranged side by side. This is because a resin having a urethane bond is excellent in flexibility, and easily deforms when pressure is applied by a welding electrode, and particularly ensures contact between conductive particles. It is thought that this is because it is easy to prevent cracking and cracking of the coating film at the time, and it is strong against deterioration because it is a chemically strong bond. In addition, when a resin containing a urethane bond is used in the coating film, excellent adhesion with the upper electrodeposition coating film can be ensured.

  There are no particular limitations on the conductive particles (α) of the present invention, and known substances can be used. For example, metals such as Zn, Ni, Fe, Al, Ag, Au, Cu, Mg, Cr, Sn, stainless steel, and Si, particles of alloys and semiconductors, iron compounds such as iron phosphide, ferrosilicon, and ferromanganese Examples thereof include oxide particles such as NiO and ZnO, and carbon particles such as carbon black, graphite, and carbon nanotube. The shape of the particles is not particularly limited, and may be a lump shape, flake shape, spherical shape, indefinite shape, fiber shape, whisker shape, chain shape, or the like. These conductive particles may be used alone or in combination of two or more.

  Among these conductive particles, ferrosilicon is particularly preferable. Ferrosilicon has conductivity and has an effect of improving corrosion resistance. That is, they are generally conductive particles that can simultaneously improve contradictory conductivity and corrosion resistance, and are extremely suitable for improving corrosion resistance while ensuring weldability and electrodeposition coating properties. Although the mechanism for improving the corrosion resistance has not been fully elucidated, it is presumed that it dissolves when the coating layer becomes an alkaline environment due to corrosion and forms a strong silica coating to suppress corrosion. Ferrosilicon also has different types of Si content. In particular, ferrosilicon having a Si content of 70% by mass or more, for example, JIS No. 2 ferrosilicon having a Si content of 75 to 80% by mass, and the like are conductive particles. As a result, it is possible to ensure weldability and electrodeposition coating properties and improve corrosion resistance.

  It is preferable that content of the electroconductive particle ((alpha)) contained in the organic coating film (A) of this invention is 15-60 volume%. If it is less than 15% by volume, sufficient weldability and electrodeposition coating properties may not be obtained. If it exceeds 60% by volume, the organic coating film (A) may become brittle and long-term corrosion resistance may be reduced. In addition, the adhesion with the electrodeposition coating film (B) of the upper layer may be lowered. When the conductive particles (α) contain ferrosilicon, the content as ferrosilicon is preferably 15 to 60% by volume. If it is less than 15% by volume, sufficient weldability and electrodeposition coating properties may not be obtained. If it exceeds 60% by volume, the organic coating film (A) may become brittle and long-term corrosion resistance may be reduced. In addition, the adhesion with the electrodeposition coating film (B) of the upper layer may be lowered.

  Although it does not specifically limit as a rust preventive pigment ((beta)) of this invention, For example, well-known rust preventive pigments, such as hexavalent chromate salts, such as strontium chromate and calcium chromate, can be used.

  When it is desired to avoid the use of a compound containing chromium as a rust preventive pigment, it is preferable to use a rust preventive pigment that releases one or more of silicate ions, phosphate ions, and vanadate ions. When these anticorrosive pigments are used, the interface between the organic coating film (A) and the formed electrodeposition coating film (B) becomes an alkaline environment when electrodeposition coating is applied, and partly dissolves the ions. Release. It is considered that the released ions are taken into the formed electrodeposition coating film (B) and act as a crosslinking agent for the electrodeposition coating film (B) or as a catalyst for the crosslinking agent. Therefore, these rust preventive pigments not only act as a rust preventive pigment of the organic coating film (A), but also have an effect of increasing the crosslinking density of the electrodeposition coating film (B) and improving the barrier property. It is thought that excellent corrosion resistance is expressed by a synergistic effect. Each of these anti-corrosion pigments exhibits excellent anti-rust effect and improved barrier property of the electrodeposition coating film, but among them, anti-rust pigments that can simultaneously release phosphate ions and vanadate ions have anti-rust effects. From the viewpoint of It is considered that silicate ions, phosphate ions and vanadate ions released in the organic coating film form a hardly soluble salt or oxide film to suppress corrosion. The reason why a particularly excellent antirust effect is exhibited by the coexistence of phosphate ions and vanadate ions is not clear, but the coexisting coatings of both were excellent in forming a denser and stronger coating than each of them. It is presumed as a reason for exhibiting a rust prevention effect.

  Examples of the compound that releases silicate ions include calcium silicate, aluminum silicate, magnesium silicate, sodium silicate, potassium silicate, lithium silicate, and the like.

  Phosphate ions are rarely present alone in an aqueous solution and exist in various forms, for example, as condensates. Even in such a case, “phosphate ion” in the present specification means condensed phosphate. It is understood as a concept including ions.

Compounds that release phosphate ions include orthophosphoric acid, condensed phosphorus, orthophosphates or condensed phosphates of various metals, phosphorus pentoxide, phosphate minerals, commercially available complex phosphate pigments, or these A mixture etc. are mentioned. The orthophosphate referred to here includes salts of its monohydrogen salt (HPO ₄ ²⁻ ) and dihydrogen salt (H ₂ PO ₄ ⁻ ). The condensed phosphate includes a hydrogen salt. In addition, the condensed phosphate includes metaphosphate, and includes ordinary polyphosphate and polymetaphosphate. Specific examples of the phosphorus compound include phosphate minerals such as monetite, tolufilite, witrockite, xenotime, starcolite, struvite, lanthanum ore, and commercially available complex phosphate pigments such as polyphosphoric acid. Silica, etc., complex phosphates such as pyrophosphate, metaphosphate, complex phosphates such as metaphosphate, tetrametaphosphate, hexametaphosphate, pyrophosphate, acidic pyrophosphate, tripolyphosphate Or a mixture thereof. The metal species forming the phosphate is not particularly limited, and examples thereof include alkali metal, alkaline earth metal, metal species of other typical elements, and transition metals. Examples of preferable metal species include magnesium, calcium, strontium, barium, titanium, zirconium, manganese, iron, cobalt, nickel, zinc, aluminum, lead, tin and the like.

  In addition, oxo cations such as vanadyl, titanyl, zirconyl and the like are also included. Particularly preferred are calcium and magnesium. The use of a large amount of alkali metal is not preferred. When an alkali metal phosphate is used, the fired product tends to dissolve too much in water. However, when an alkali metal phosphate is used, it may be used as long as the solubility in water can be controlled at the time of production of the rust inhibitor or at other times. Such control includes, for example, various modes such as the use of a matrix material (particularly, a glassy substance) for preventing solubility in water, or coating.

  The compound that releases vanadate ions is a compound having a valence of vanadium of any one of 0, 2, 3, 4 or 5, or a valence of two or more. These oxides, water Examples thereof include oxides, oxyacid salts of various metals, vanadyl compounds, halides, sulfates, and metal powders. These decompose when heated or in the presence of water and react with oxygen to be upgraded. For example, a metal powder or a divalent compound finally changes to a trivalent, tetravalent, or pentavalent compound. Zero-valent ones, such as vanadium metal powder, can be used for the above reasons, but are not preferred in practice because of problems such as insufficient oxidation reaction. It is also preferable to contain a pentavalent vanadium compound as one component. The pentavalent vanadium compound has vanadate ions and reacts with phosphate ions by heating to easily form a heteropolymer. Specific examples of vanadium compounds include vanadium (II) compounds, such as vanadium (II) oxide, vanadium (II) hydroxide, vanadium (III) compounds, such as vanadium (III) oxide, vanadium (IV) compounds, such as Vanadium (IV) oxide, vanadyl halide, etc., vanadium (V) compounds such as vanadium oxide (V), vanadate, such as orthovanadate, metavanadate or pyrovanadate of various metals, halogen And vanadyl chloride, or a mixture thereof. Examples of the vanadate metal species are the same as those shown for phosphate. This may be made by baking an oxide of vanadium and various metal oxides, hydroxides, carbonates, etc. at 600 ° C. or higher. In this case as well, alkali metals are not preferred because of their solubility, but they can be used if the solubility is controlled by appropriate treatment as described for phosphate. The same applies to halides and sulfates.

The ratio of the phosphate ion source and vanadate ion source to be blended is preferably 1: 3 to 100: 1 in terms of the molar ratio of P ₂ O ₅ and V ₂ O ₅ . When the amount of vanadate ion source exceeds 1: 3 in the above molar ratio, the rust prevention effect due to phosphate ions is reduced, and the amount of vanadate ion source is less than 100: 1 in the above molar ratio Is not preferred because the oxidizer function by vanadate ions is insufficient.

  When silica is further added together with these rust preventive pigments, the corrosion resistance is further improved. Examples of silica include fumed silica, colloidal silica, and agglomerated silica. Calcium deposited silica can also be used.

  That is, the more preferable aspect of the conductive particles (α) and the rust preventive pigment (β) for ensuring excellent corrosion resistance is that ferrosilicon is used for the conductive particles (α) and the rust preventive pigment (β) is phosphorus. A compound capable of simultaneously releasing acid ions, vanadate ions, and silica coexist.

  The content of the rust preventive pigment (β) is desirably 2 to 25% by volume in the organic coating film. Preferably it is 3-20 volume%. If it is less than 2%, sufficient corrosion resistance may not be obtained, and if it exceeds 25% by volume, the weldability and workability may be lowered, or an intermediate coating may be applied to the upper layer of the electrodeposition coating film (B). There is a possibility that the water-resistant adhesion when the top coat is applied is lowered. Even when the anticorrosive pigment (β) contains a compound capable of releasing one or more of silicate ion, phosphate ion and vanadate ion, the content is 2 to 25 in the organic coating film in total. It is desirable to be volume%. If it is less than 2%, sufficient corrosion resistance may not be obtained, and if it exceeds 25% by volume, the weldability and workability may be lowered, or an intermediate coating may be applied to the upper layer of the electrodeposition coating film (B). There is a possibility that the water-resistant adhesion when the top coat is applied is lowered.

  The method for forming the organic coating film (A) of the present invention can be a known method. For example, it can be produced by producing a paint in which conductive particles are mixed with a binder component and applying the paint. Depending on the binder component and the contained components, the film can be formed by a known method such as volatilization of a solvent with heat, curing, or curing with an energy beam, if necessary. The coating method can be a known method, and examples thereof include a roll coater, roller coating, brush coating, curtain coater, die coater, slide coater, electrostatic coating, spray coating, dip coating, and air knife coating. . The form of the paint is not particularly limited, such as powder, solid, solvent-based, and water-based. It is also possible to melt the solid paint by applying heat and coat it while extruding it with a die.

  Alternatively, the coated metal plate can also be produced by kneading conductive particles in advance in the film layer and laminating the film. For laminating, an adhesive may be used, or the film may be heat-melted and directly laminated on a metal plate.

  The organic coating film (A) in the present invention may be formed on at least one side of the metal, but may be formed on both sides. When it is formed on one side, some treatment layer or coating layer may be formed on the other side, or it may be a metal surface.

  You may form a base-treatment layer for the purpose of improving the adhesiveness of the metal plate of this invention, and an organic coating film (A), or improving corrosion resistance. A known technique can be used for the base treatment layer. For example, phosphate treatment, trivalent chromic acid treatment, chromate treatment, Zr treatment, Ti treatment, Mn treatment, Ni treatment, Co Examples thereof include system processing, V system processing, coupling agent (Si system, Ti system, etc.) processing, processing with organic substances, and the like. The base treatment layer does not need to be a single layer. For example, a zinc phosphate treatment layer is formed and a sealing treatment is performed thereon, and a plurality of treatments such as a chromate treatment is performed after preconditioning with an acidic Ni-containing liquid. May be combined.

  The metal plate surface can be treated by a known method before forming the base treatment layer or before forming the coating layer when the base treatment layer is not formed. For example, treatments such as degreasing with water or hot water or a degreasing solution, etching with acid or alkali, mechanical grinding by hanging, etc. can be performed.

  Examples of the present invention will be described below. However, the present invention is not limited to these examples.

Example 1
(1) Metal materials Table 1 shows the types of metal materials used. A mild steel plate having a thickness of 0.8 mm was used as the metal base material.

(2) Ground treatment layer Table 2 shows the contents of the ground treatment layer. An aqueous treatment liquid for forming the base treatment layer was bar-coated so as to have a predetermined adhesion amount, and dried under the condition of a reaching plate temperature of 70 ° C.

(3) Organic coating The contents of the resin constituting the organic coating are shown in Table 3, the contents of the conductive particles are shown in Table 4, and the contents of the rust preventive pigment are shown in Table 5, respectively. A solvent-based paint for forming an organic coating film is bar-coated on the metal material on which the base treatment layer is formed so as to have a predetermined dry film thickness, baked at a reaching plate temperature of 200 ° C., and then immediately cooled with water. .

(4) Sample preparation (part 1)
The coated metal material produced in the above (3) was processed into the following test pieces.
Test piece A: flat plate of 70 × 150 mm size (planar and end surface test specimens)
Specimen B: 70 × 150 mm size flat plate (scratch investigation specimen)
Specimen C: Cylindrical cup-molded product (test piece for processing section investigation)
Cylindrical cup molding of test piece C is applied with punch diameter 50mmφ, punch shoulder radius 3mm, die diameter 50mmφ, die shoulder radius 3mm, drawing ratio 1.8, wrinkle holding pressure 1 ton, processing oil (PG3080 / manufactured by Nippon Kogyo Oil Co., Ltd.) It carried out on condition of this.

(5) Washing After the test pieces A, B and C prepared in the above (4) were sprayed (degreased) for 2 minutes with a 2% by weight aqueous solution of Surf Cleaner EC92 (manufactured by Nippon Paint Co., Ltd.) with tap water, Spray treatment (washed with water) for 30 seconds.

(6) Chemical conversion treatment The test pieces A, B and C washed in (5) above were sprayed with a 0.1% by weight aqueous solution of Surffine 5N-8 (manufactured by Nippon Paint Co., Ltd.) at 40 ° C. for 30 seconds (surface adjustment). Subsequently, after spray treatment (chemical conversion treatment) at 35 ° C. for 2 minutes with a 6 mass% aqueous solution of SD5350 (manufactured by Nippon Paint Co., Ltd.), it was sprayed with tap water (water washing) for 30 seconds.

(7) Electrodeposition coating The test pieces A, B, and C that have undergone the chemical conversion treatment step in (6) above have a predetermined dry film thickness using Powernics 110 (manufactured by Nippon Paint Co., Ltd., paint that does not substantially contain lead). The electrodeposition coating was performed, and after spraying (washing with water) for 30 seconds with tap water, baking was performed by heating at 170 ° C. for 20 minutes.

(8) Sample preparation (2)
For the test piece A subjected to electrodeposition coating in (7) above, the lower half was cross-cut with a cutter knife, and then the upper, lower, left and right end surfaces and the back surface were painted and sealed (the upper half was a flat part and the lower half was a scratched part) For research). About the test piece B, only the upper and lower end surfaces and the back surface were painted and sealed (the end surface portion was investigated at the left and right end surfaces). About the test piece C, the end surface and the back surface were paint-sealed (the processed part was investigated in the shoulder part and the side part of the molded product).

(9) Intermediate coating / top coating The test piece subjected to electrodeposition coating in (7) above was spray-coated using OP-2 (manufactured by Nippon Paint Co., Ltd.) to a dry film thickness of 35 μm, and 140 ° C. And baked for 20 minutes to form an intermediate coating film. Next, spray coating is performed on the intermediate coating film using OP-058 (manufactured by Nippon Paint Co., Ltd.) to a dry film thickness of 35 μm, and baking is performed by heating at 140 ° C. for 20 minutes to form a top coating film. did.

(10) Sample preparation (part 3)
For test piece A with the intermediate coating and top coating applied in (9) above, the lower half was cross-cut with a cutter knife, and then the top, bottom, left, and right end surfaces and the back surface were painted and sealed (the upper half was the flat surface and the lower half was For wound investigation). About the test piece B, only the upper and lower end surfaces and the back surface were painted and sealed (the end surface portion was investigated at the left and right end surfaces). About the test piece C, the end surface and the back surface were paint-sealed (the processed part was investigated in the shoulder part and the side part of the molded product).

  Table 6 shows the contents of the test piece prepared in the above (8) or (10). The film thickness of each coating layer was measured by embedding the cut specimen in an epoxy resin, polishing the cut surface, and observing the cut surface with an optical microscope. The test piece prepared in the above (8) is subjected to the corrosion resistance test shown below, and the test piece prepared in the above (10) is subjected to the following corrosion resistance test and water-resistant adhesion test (only the test piece B). Carried out.

<Corrosion resistance test>
A cyclic corrosion test was performed with a total of 8 hours of 2 hours of salt spray, 4 hours of drying, and 2 hours of wetness as one cycle. The salt spray conditions were as per JIS Z 2371. The drying conditions were a temperature of 60 ° C. and a humidity of 30% RH or less, and the wet conditions were a temperature of 50 ° C. and a humidity of 95% RH or more. The occurrence of red rust in the flat portion, cross-cut portion (test piece A), end face portion (test piece B), and processed portion (test piece C) was evaluated according to the following evaluation criteria.

Score 5: No red rust generated in 600 cycles Score 4: No red rust generated in 450 cycles Score 3: No red rust generated in 300 cycles Score 2: No red rust generated in 150 cycles Score 1: Red rust generated in 150 cycles

<Water-resistant adhesion>
After immersing in pure water at 40 ° C. for 240 hours, a grid (100 pieces) with a 2 mm interval is formed in the center of test piece B with a cutter knife, and an adhesive tape is applied to the surface, and then the tape is peeled off. Then, the number of peeled coating films was measured.

  Table 7 shows the performance investigation results of the organic coating film (A) + electrodeposition coating film (B) prepared in (8) above. The examples of the present invention showed excellent corrosion resistance of the flat portion, the cross cut portion, the end face portion, and the processed portion having a rating of 3 or more in any sample form. Moreover, depending on the structure of an Example, the grades 4 and 5 and the better corrosion resistance are shown. In addition, No. 42 is excellent in corrosion resistance, but contains Cr as a rust preventive pigment.

  On the other hand, No. which does not contain a rust preventive pigment in the organic coating film (A) which is a comparative example out of the scope of the present invention. 51, no organic coating film (A). No. 52-54, no electrodeposition coating film (B). Each of 55 and 56 has a sample form in which the corrosion resistance with a rating of 2 or less is lowered.

  Table 8 shows the performance investigation results of the organic coating film (A) + electrodeposition coating film (B) + intercoat and top coating film prepared in (10) above. The examples of the present invention showed excellent corrosion resistance of the flat part, cross-cut part, end face part and processed part with a rating of 3 or more and excellent water-resistant adhesion with a peel number of 1 or less in any sample form. Moreover, depending on the structure of an Example, the rating 4 and 5 and the more excellent corrosion resistance are shown, and the water-resistant adhesiveness of the peeling number 0 is shown more. In addition, No. 42 is excellent in corrosion resistance and water adhesion, but contains Cr in the rust preventive pigment.

  On the other hand, No. which does not contain a rust preventive pigment in the organic coating film (A) which is a comparative example out of the scope of the present invention. 51, no organic coating film (A). 52-54, there is a sample form in which the corrosion resistance with a rating of 2 or less decreases. In addition, No. having no electrodeposition coating film (B). Although 55 and 56 have the corrosion resistance of the plane part, crosscut part, end surface part, and process part which were excellent in the grade 3 or more, water-resistant adhesiveness is bad.

(Example 2)
The metal material which gave the organic coating film (A) on both surfaces in the same way as said (1)-(3) was produced, and it processed into the following test pieces.
Specimen D: Bag-like processed product (test specimen for investigating defective areas with electrodeposition)
The bag-like processed product of the test piece D was manufactured by preparing two square tube molded processed products, aligning each convex shape up and down, and joining the flange portions by laser welding. Electrodeposition holes with a diameter of 20 mm were formed above and below the bag-shaped part. Square tube molding is punch size 65mm x 115mm, punch shoulder radius 10mm, die shoulder radius: 5mm, molding speed: 40spm, molding height: 50mm, wrinkle holding pressure: 4 tons, processing oil (PG3080 / manufactured by Nippon Kogyo Oil Co., Ltd.) It implemented using the crank press molding machine on the conditions of application | coating.

  Subsequently, chemical conversion treatment and electrodeposition coating were performed in the same manner as the above (5) to (7). Electrodeposition coating was performed so that the outer surface of the bag-like processed product had a predetermined dry film thickness. Table 9 shows the contents of the prepared test pieces. Sites A and B where the electrodeposition coating film on the inner surface of the bag-like processed product is thinner than the outer surface (the electrodeposition coating is poor) were cut out and the above corrosion resistance test was performed. The actual film thicknesses of the parts A and B at this time are shown in Table 9. Table 10 shows the results of the corrosion resistance test.

  The examples of the present invention showed excellent corrosion resistance with a rating of 5 even in a thin film portion with poor electrodeposition coating. On the other hand, in the comparative example without the organic coating film (A), the corrosion resistance was lowered in the thin film portion where the electrodeposition coating was poor.

As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be envisaged within the scope of the claims, and these are naturally within the technical scope of the invention. Is done.

Claims (12)

At least one surface of the metal material has an organic coating film (A) containing conductive particles (α) and an antirust pigment (β),
An automobile member having an electrodeposition coating film (B) formed from an electrodeposition coating material substantially free of lead in the upper layer of the organic coating film.   The automobile member according to claim 1, further comprising one or more coating films on an upper layer of the automobile member. When T _A is the thickness of the organic coating film (A) and T _B is the thickness of the electrodeposition coating film (B), T _A ≧ 2 μm, T _B ≧ 3 μm, and T _A + T _B ≧ 8 μm are satisfied. The automobile member according to claim 1 or 2, wherein The conductive wherein the minimum value of the thickness T _B of the coating film (B) is 10μm or less, an automobile member according to any one of claims 1 to 3.   The automobile member according to any one of claims 1 to 4, wherein the conductive particles (α) contain ferrosilicon.   The automobile member according to claim 5, wherein a content of Si contained in the ferrosilicon is 70% by mass or more.   The automobile member according to claim 1, wherein the content of the conductive particles (α) contained in the organic coating film (A) is 15 to 60% by volume.   The automobile member according to any one of claims 1 to 7, wherein the rust preventive pigment (β) does not contain chromium.   The automobile member according to any one of claims 1 to 8, wherein the antirust pigment (β) contains a compound capable of releasing at least one of silicate ions, phosphate ions, and vanadate ions.   The automobile member according to any one of claims 1 to 9, wherein the content of the anticorrosive pigment (β) contained in the organic coating film (A) is 2 to 25% by volume.   The automobile component according to any one of claims 1 to 10, wherein the binder component in the organic coating film (A) contains a resin containing a urethane bond. The automobile member according to any one of claims 1 to 11, wherein the metal material is a zinc-based plated steel plate or an aluminum-based plated steel plate.