CN110770368A

CN110770368A - Magnesium-containing metal material with film

Info

Publication number: CN110770368A
Application number: CN201880040560.6A
Authority: CN
Inventors: 上田幸宏; 大槻哲郎; 万隆行; 桂谷凉子; 神山直澄
Original assignee: Japan Pakasai Sperm Co Ltd
Current assignee: Japan Pakasai Sperm Co Ltd; Nihon Parkerizing Co Ltd
Priority date: 2017-06-22
Filing date: 2018-06-20
Publication date: 2020-02-07
Also published as: EP3643811A4; KR102354534B1; US20200109474A1; JP2019007044A; CN114807937A; EP3643811A1; US20210172067A1; JP6872987B2; KR20200010399A; WO2018235863A1

Abstract

The invention provides a magnesium-containing metal material having a coating film on the surface, the coating film having excellent corrosion resistance. Specifically, the present invention provides a magnesium-containing metal material with a coating film, which is characterized in that a first coating film containing magnesium hydroxide is provided on the surface of a magnesium-containing metal material formed of magnesium or a magnesium alloy, a third coating film containing hydroxyapatite and/or hydroxyapatite is provided on the first coating film, and a second coating film containing calcium hydrogen phosphate is provided between the first coating film and the third coating film.

Description

Magnesium-containing metal material with film

Technical Field

The present invention relates to a magnesium material or a magnesium alloy material having a corrosion-resistant coating film formed on the surface thereof (hereinafter, the magnesium material, the magnesium alloy material, and the like are referred to as "magnesium-containing metal materials").

Background

Magnesium-containing metal materials have a low specific gravity and are being studied for use as structural materials for airplanes, automobiles, bicycles, home electric appliances, medical devices, fishing gears, and the like because of their lightweight properties. However, because of the high corrosion susceptibility of magnesium-containing metallic materials, certain surface treatments are required to improve corrosion resistance.

As a surface treatment for improving corrosion resistance, various methods have been developed. For example, patent document 1 proposes a surface treatment method: a magnesium or magnesium alloy substrate molded into a predetermined shape is immersed in an aqueous solution in which phosphate ions and non-chloride calcium ions are dissolved in a supersaturated state, and a bioabsorbable coating mainly composed of apatite crystals is deposited on the surface of the substrate.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2010-148682.

Disclosure of Invention

Problems to be solved by the invention

The corrosion resistance of the coating film obtained by the surface treatment method described in patent document 1 is insufficient. Accordingly, an object of the present invention is to provide a magnesium-containing metal material or the like having a coating film on the surface thereof, the coating film having excellent corrosion resistance.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a magnesium-containing metal material having a coating film comprising magnesium hydroxide, a coating film comprising calcium hydrogen phosphate, and a coating film comprising hydroxyapatite and/or hydroxyapatite in this order on the surface is excellent in corrosion resistance, and have completed the present invention.

Namely, the present invention is:

(1) a magnesium-containing metal material with a film, characterized in that a first film containing magnesium hydroxide is provided on the surface of a magnesium-containing metal material formed of magnesium or a magnesium alloy, a third film containing hydroxyapatite and/or hydroxyapatite carbonate is provided on the first film, and a second film containing calcium hydrogen phosphate is provided between the first film and the third film;

(2) the magnesium-containing metal material with a coating film according to (1), wherein the second coating film is a coating film containing monetite (monetite) and/or brushite (brister).

Effects of the invention

According to the present invention, a magnesium-containing metal material having a coating film on the surface thereof, which coating film has excellent corrosion resistance, can be provided.

Detailed Description

Hereinafter, a magnesium-containing metal material with a coating film and a method for producing the same, which are embodiments of the present invention, will be described in detail.

< magnesium-containing metal material with coating >

A magnesium-containing metal material with a coating film according to an embodiment of the present invention has a first coating film containing magnesium hydroxide on a surface of the magnesium-containing metal material, a third coating film containing hydroxyapatite and/or hydroxyapatite carbonate on the first coating film, and a second coating film containing calcium hydrogen phosphate between the first coating film and the third coating film. The magnesium-containing metal material with the coating has excellent corrosion resistance.

(magnesium-containing Metal Material)

The magnesium-containing metal material to be treated with the coating film is a metal material containing magnesium as a main component, such as a magnesium material or a magnesium alloy material. In the case where the magnesium alloy material is formed of two metal components, 50% by weight or more of magnesium may be contained, and 80% by weight or more of magnesium is preferably contained. Further, in the case where the magnesium alloy material is formed of three or more metal components, it is sufficient that magnesium is contained at most. Examples of the kind of magnesium alloy material include AZ91, AM60, ZK51, ZK61, AZ31, AZ61, and ZK 60.

(film containing magnesium hydroxide)

The first film of the present embodiment is not particularly limited as long as it contains magnesium hydroxide, and may contain a metal component such as aluminum, zinc, or zirconium. The magnesium hydroxide may be crystalline magnesium hydroxide and/or amorphous magnesium hydroxide, and preferably includes crystalline magnesium hydroxide. When both are included, the content ratio is not particularly limited. Whether or not these components are present in the coating film can be confirmed by X-ray diffraction (XRD).

The film thickness of the first film is not particularly limited. Usually 0.1 μm or more, and may be 1 μm or more, and further usually 100 μm or less, and may be 30 μm or less, and may be 20 μm or less. The film thickness can be determined by observing the cross-sectional shape of the film using a Scanning Electron Microscope (SEM).

(film containing calcium hydrogen phosphate)

The second film of the present embodiment is not particularly limited as long as it contains calcium hydrogen phosphate. The calcium hydrogen phosphate crystal contained in the coating can be monetite and/or brushite. The coating preferably contains brushite. When both are included, the content ratio is not particularly limited. In addition, the presence or absence of crystals of calcium hydrogen phosphate in the film can be confirmed by X-ray diffraction (XRD).

The average primary particle size of the crystalline particles of calcium hydrogen phosphate in the second film is not particularly limited, and is usually 0.7 μm or more, and may be 3 μm or more, and further 100 μm or less, and may be 30 μm or less, and may be 10 μm or less. The average primary particle diameter can be determined by observation with a scanning electron microscope. Specifically, the maximum diameter and the minimum diameter of 100 randomly selected crystalline calcium hydrogen phosphate particles were measured, and the average of the particle diameters was calculated from 200 data obtained as the average primary particle diameter.

The film thickness of the second film is not particularly limited. Usually 0.01 μm or more, and may be 1 μm or more, and may be 2 μm or more, and further usually 100 μm or less, and may be 25 μm or less, and may be 20 μm or less. The film thickness can be determined by observing the cross-sectional shape of the film using a Scanning Electron Microscope (SEM).

(coating film comprising hydroxyapatite and/or hydroxyapatite carbonate)

The third coating film of the present embodiment is not particularly limited as long as it contains hydroxyapatite and/or hydroxyapatite carbonate. Further, in the case where both hydroxyapatite and carbonated hydroxyapatite are contained, the content ratio thereof is not particularly limited. Whether or not the coating contains hydroxyapatite and/or hydroxycarbonated hydroxyapatite can be confirmed by X-ray diffraction (XRD).

< method for producing magnesium-containing metal material with coating film >

The magnesium-containing metal material with a coating film of the present embodiment can be produced by a method including, for example, the following steps: the method for forming the calcium phosphate-based coating comprises a first step of forming a first coating on the surface of a magnesium-containing metal material, a second step of forming a second coating on the first coating, and a third step of converting calcium hydrogen phosphate crystals on part or all of the surface of the second coating into hydroxyapatite and/or hydroxyapatite to form a third coating. The magnesium-containing metal material with a coating film of the present embodiment can also be produced by a method including a step of forming a third coating film on the second coating film after the second step.

(first step)

Examples of a method for forming the first film on the surface of the magnesium-containing metal material include known methods such as a water vapor treatment method (also referred to as a "hydrothermal treatment" or a "magnesium hydroxide film forming treatment"), but the method is not limited to this method. In the case where the first step is performed by a steam treatment method, the time for the steam treatment may be usually 1 minute or more, 30 minutes or more, or 60 minutes or more. Further, the reaction time may be usually 1440 minutes or less, may be 600 minutes or less, and may be 300 minutes or less.

(second Process)

Examples of a method for forming the second coating on the first coating include, but are not limited to, a chemical conversion treatment method in which an aqueous solution (chemical conversion treatment agent) containing phosphate ions (リン acid イオン) and calcium ions is brought into contact with the surface of the magnesium-containing metal material having the first coating. Examples of the source of phosphate ions include phosphoric acid and water-soluble phosphate. Examples of the source of calcium ions include: calcium hydroxide, calcium carbonate, calcium nitrate, and the like.

The concentration of calcium ions and the concentration of phosphate ions in the chemical conversion treatment agent are not particularly limited as long as they can form a chemical film having crystals of calcium hydrogen phosphate on the magnesium-containing metal material. The phosphate ion concentration is usually 500ppm or more, may be 1000ppm or more, and is usually 20000ppm or less, may be 10000ppm or less. The calcium ion concentration is usually 100ppm or more, and may be 500ppm or more, and further usually 10000ppm or less, and may be 5000ppm or less.

The pH of the chemical conversion treatment agent is usually 2.0 or more, and may be 3.0 or more, and may be 4.0 or more, and is usually 5.0 or less, and may be 4.5 or less. The pH adjuster for adjusting the pH of the chemical conversion agent is not particularly limited, and an acidic component such as nitric acid, phosphoric acid, or sulfuric acid, or a basic component such as sodium hydroxide, sodium carbonate, ammonia water, or ammonium hydrogen carbonate can be used.

The method of contacting the chemical conversion treatment agent is not particularly limited, and examples thereof include: spraying treatment, dipping treatment, electrolysis treatment, rinsing treatment, and the like. The contact temperature of the chemical conversion treatment agent is not particularly limited, and is usually 10 ℃ or higher, may be 40 ℃ or higher, may be 70 ℃ or higher, and is usually 100 ℃ or lower, and may be 90 ℃ or lower.

The contact time of the chemical conversion treatment agent is not particularly limited, and is usually 1 minute or more, may be 3 minutes or more, and may be 5 minutes or more, and is usually 60 minutes or less, may be 30 minutes or less, and may be 15 minutes or less.

< third Process step >

Examples of a method for forming the third film by converting part or all of the calcium hydrogen phosphate crystals on the surface of the second film into hydroxyapatite and/or hydroxyapatite carbonate include, for example, a method in which an alkaline aqueous solution is brought into contact with the surface of the second film, but the method is not limited thereto. The alkaline component contained in the alkaline aqueous solution is not particularly limited, and examples thereof include: lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, potassium sodium carbonate, calcium carbonate, and the like. These basic components may be used alone or in combination of two or more. As the alkaline aqueous solution, a solution obtained by dissolving carbon dioxide in an aqueous solution containing lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, or the like can be used.

The concentration of the alkaline component in the alkaline aqueous solution is not particularly limited, and is usually not less than 0.01g/L, but may be not less than 1g/L, and is usually not more than 2000g/L, but may be not more than 500 g/L. The pH of the alkaline aqueous solution is usually 7.5 or more, and may be 8.0 or more.

The method of contacting the aqueous alkaline solution is not particularly limited, and examples thereof include: coating treatment, spraying treatment, dipping treatment, rinsing treatment, and the like. In addition, when the magnesium-containing metal material having the first and second films is immersed in an alkaline aqueous solution containing lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, or the like, the immersion treatment may be performed while blowing carbon dioxide into the alkaline aqueous solution.

The contact temperature of the alkaline aqueous solution is not particularly limited, and is usually 10 ℃ or higher, may be 30 ℃ or higher, and is usually 140 ℃ or lower, and may be 100 ℃ or lower. The contact time of the alkaline aqueous solution is not particularly limited, and is usually not less than 1 second, but may be not less than 1 minute, and is usually not more than 360 minutes, but may be not more than 30 minutes.

In the method for producing a magnesium-containing metallic material with a coating film according to the present embodiment, a step of forming a third coating film on the second coating film after the second step may be performed instead of the third step. The method for forming the third film is not particularly limited as long as it is a known method, and examples thereof include: a method of electrically heating in a calcium phosphate solution, a method of irradiating hydroxyapatite powder with an ultrafine particle beam, and the like.

In the method for producing the magnesium-containing metal material with a coating film, the surface of the magnesium-containing metal material may be subjected to a pretreatment step such as solvent cleaning, alkali cleaning, degreasing, acid cleaning, etching, desmutting, paper grinding, buffing, or the like, or two or more pretreatment steps may be sequentially performed before the first step. By these pretreatment steps, an oxide film of the magnesium-containing metal material, oil and dirt adhering to the magnesium-containing metal material, and the like can be removed, and the surface can be cleaned.

Further, in the method for producing a magnesium-containing metal material with a coating film, the surface conditioning step may be performed using a surface conditioner after the first step and before the second step in order to efficiently form the second coating film.

The surface conditioning step is a step of bringing the surface conditioning agent into contact with the magnesium-containing metal material having the first coating film. Examples of the method of contacting the surface conditioner include: spray coating, dip coating, roll coating, curtain coating, spin coating, or a method in which these are combined as appropriate.

The contact temperature of the surface conditioner is the temperature of the surface conditioner or the temperature of the magnesium-containing metal material having the first film, and is usually 0 ℃ or higher, and may be 10 ℃ or higher, and is usually 40 ℃ or lower, and may be 30 ℃ or lower.

The contact time of the surface conditioner is usually 1 second or more, may be 5 seconds or more, may be 10 seconds or more, and further usually 10 minutes or less, may be 5 minutes or less, may be 3 minutes or less, and may be 1 minute or less.

After the pretreatment step, the first step, the surface conditioning step, the second step, the third step, and the like, a washing step by water washing may be performed. If necessary, the drying step may be performed after each washing step as appropriate.

< surface conditioner >

The surface conditioner contains calcium hydrogen phosphate particles having a specific particle diameter.

The surface conditioner of the present embodiment may contain components other than the solvent and the calcium hydrogen phosphate particles as long as the effects of the present invention can be exhibited, but may be formed of only the solvent and the calcium hydrogen phosphate particles.

(calcium Hydrogen phosphate granules)

Dibasic calcium phosphate is also known as dibasic calcium phosphate. In calcium hydrogen phosphate, anhydrous compounds (CaHPO) are present₄) And dihydrate (CaHPO)₄·2H₂O), the anhydrate is called monetite and the dihydrate is called brushite.

The surface conditioner of the present embodiment may contain at least one of monetite and brushite, or both. When both are included, the content ratio is not particularly limited.

The calcium hydrogen phosphate may be crystalline calcium hydrogen phosphate or amorphous calcium hydrogen phosphate, and crystalline calcium hydrogen phosphate is generally used.

Further, calcium hydrogen phosphate may be produced from a commercially available product or a phosphoric acid raw material and a calcium raw material. The method for producing calcium hydrogen phosphate can be obtained by, for example, reacting a calcium raw material such as calcium carbonate or calcium hydroxide with an aqueous phosphoric acid solution to adjust the pH to 4 to 5. In this case, monetite is obtained by setting the reaction temperature to at least 80 ℃ or higher, and brushite is obtained by setting the reaction temperature to at least 60 ℃ or lower. It should be noted that monetite is sometimes obtained even at temperatures lower than 80 ℃ and brushite is sometimes obtained even at temperatures higher than 60 ℃.

In the case of granules of calcium hydrogen phosphate, D₅₀Usually 0.1 μm or more, may be 0.2 μm or more, and may be 0.3 μm or more. The upper limit is usually 0.8 μm or less, but may be 0.6 μm or less, or may be 0.5 μm or less.

In addition, in the case of granules of calcium hydrogen phosphate, D thereof₉₀Usually 0.15 μm or more, may be 0.2 μm or more, and may be 0.3 μm or more. The upper limit is usually 1.5 μm or less, may be 1.2 μm or less, and may be 1.0 μm or less.

D₅₀And D₉₀The particle diameters are represented by 50 vol% and 90 vol%, respectively, when the cumulative curves of the particles are determined using the total volume of the calcium hydrogen phosphate particles in the surface conditioner as 100%. The particle size distribution of the calcium hydrogen phosphate particles in the surface conditioner can be determined by analyzing the intensity of light scattered from the particles irradiated with the laser light and a diffraction image generated on a focal plane by condensing the light with a lens, for example. From the obtained particle size distribution, particle diameters at 50% by volume and 90% by volume can be obtained.

The particle size of the calcium hydrogen phosphate particles can be adjusted by a conventional method such as wet grinding. More specifically, it can be adjusted by pulverizing a mixture of water, a dispersant and calcium hydrogen phosphate particles with a bead mill. In addition, the mass concentration of the calcium hydrogen phosphate particles in the mixture is not particularly limited, and is preferably 5 to 50 wt%.

(dispersing agent)

Examples of the dispersant include: monosaccharides or polysaccharides, or derivatives thereof; orthophosphoric acid, polyphosphoric acid or a salt thereof, or an organic phosphonic compound or a salt thereof; a water-soluble polymer compound formed from a polymer of vinyl acetate or a derivative thereof, or a copolymer of vinyl acetate and a monomer copolymerizable with vinyl acetate; will be selected from the formulae: h₂C＝C(R¹)-COOR²(in the formula, R¹Is H or CH₃，R²H, 1 to 5C alkyl groups, or 1 to 5C hydroxyalkyl groups), or α -unsaturated carboxylic acid monomer, and 50 wt% or less of a monomer copolymerizable with the monomer.

Examples of the basic constituent saccharides of the above monosaccharides, polysaccharides, or derivatives thereof include: fructose, tagatose, psicose, sorbose, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose, galactose, talose, and the like.

In the case of using monosaccharides, the above-mentioned basic constitutional saccharides themselves may be used; when polysaccharides are used, the above-mentioned homopolysaccharides or heteropolysaccharides that substantially constitute saccharides can be used; further, as derivatives thereof, NO can be used which is a hydroxyl group that substantially constitutes a saccharide₂、CH₃、C₂H₄OH、CH₂CH(OH)CH₃、CH₂Monosaccharides obtained by etherification of substituents such as COOH, and homo-or heteropolysaccharides comprising monosaccharides substituted with the above substituents in their structure. In addition, several types of monosaccharides, polysaccharides, and derivatives thereof may be used in combination.

When saccharides are classified, they may be classified into monosaccharides, oligosaccharides, and polysaccharides based on the degree of hydrolysis, but in the present invention, saccharides that produce two or more monosaccharides by hydrolysis are used as polysaccharides, and saccharides that cannot be hydrolyzed further by themselves are used as monosaccharides.

In the embodiment of the present invention, the steric configuration (D configuration, L configuration) and the optical activity (+, -) of the monosaccharide and the monosaccharide constituting the oligosaccharide and the polysaccharide are not particularly limited, and the steric configuration and the optical activity of each monosaccharide constituting the oligosaccharide and the polysaccharide may be the same as each other, partially the same as each other, or may be different from each other. In addition, in order to improve the water solubility of monosaccharides, polysaccharides, and derivatives thereof, sodium salts or ammonium salts of the above monosaccharides, polysaccharides, and derivatives thereof can be used. Further, in the case where the above-mentioned structure is hardly soluble in water, it can be used after being dissolved in an organic solvent having compatibility with water in advance.

Orthophosphoric acid is ortho-phosphoric acid. As the polyphosphoric acid, for example: pyrophosphoric acid, triphosphoric acid, trimetaphosphoric acid, tetrapolymetaphosphoric acid, hexametaphosphoric acid or sodium salt or ammonium salt thereof, and the like. Further, as the organic phosphonic acid compound, for example: aminotrimethylene phosphonic acid, 1-hydroxyethylidene-1, 1-diphosphonic acid, ethylenediamine tetramethylene phosphonic acid, diethylene triamine pentamethylene phosphonic acid or sodium salts thereof, and the like. One of orthophosphoric acid, polyphosphoric acid, and organophosphonic acid compounds may be used, or two or more of them may be used in combination.

As the vinyl acetate polymer or derivative thereof, for example: polyvinyl alcohol which is a saponified product of a vinyl acetate polymer, cyanoethylated polyvinyl alcohol in which polyvinyl alcohol is further cyanoethylated with acrylonitrile, polyvinyl formal in which polyvinyl alcohol is acetalized with formalin, polyvinyl alcohol urethane in which polyvinyl alcohol is carbamated with urea, and a water-soluble polymer compound in which a carboxyl group, a sulfone group, an amide group, and the like are introduced into polyvinyl alcohol. The term "water-soluble" as used herein means a property of dissolving 0.1g or more of a substance in 100g of water at 25 ℃ or a property of making a mixture of the substance and water transparent (the same applies hereinafter in the present specification). As the monomer copolymerizable with vinyl acetate of the present invention, for example, there can be used: acrylic acid, crotonic acid, maleic anhydride, and the like.

The vinyl acetate polymer or a derivative thereof, or a copolymer of vinyl acetate and a monomer copolymerizable with vinyl acetate may be water-soluble. Therefore, the effect is not influenced by the degree of polymerization and the introduction rate of the functional group. One of a polymer of vinyl acetate, a derivative thereof, and a copolymer thereof may be used, or two or more thereof may be used in combination.

As the monomer represented by the above formula, for example: methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypentyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxypentyl methacrylate, and the like.

The α -unsaturated carboxylic acid monomer may be, for example, acrylic acid, methacrylic acid, maleic acid, or the like, and the monomer copolymerizable with the above-mentioned monomers may be, for example, vinyl acetate, styrene, vinyl chloride, vinyl sulfonic acid, or the like.

(solvent)

The solvent is not particularly limited as long as calcium hydrogen phosphate can be dispersed appropriately, and water is usually used. In this case, the content of the organic solvent may be usually 10% by weight or less, 5% by weight or less, or 3% by weight or less based on the total amount of the solvent.

The type of the organic solvent is not particularly limited, and examples thereof include: alcohol-based organic solvents, hydrocarbon-based organic solvents, ketone-based organic solvents, amide-based organic solvents, and the like.

The content of calcium hydrogen phosphate particles in the surface conditioner is usually 0.05g/L or more, and may be 0.1g/L or more as a solid content concentration. The upper limit is usually 20g/L or less, may be 10g/L or less, and may be 5g/L or less. When the amount is within this range, the dispersibility of the calcium hydrogen phosphate particles of the surface conditioner is good.

(other Components)

The surface conditioner may comprise, as required: a thickener, a dispersion stability improver, a pH adjuster, and the like.

The tackifier can ensure the dispersibility of calcium hydrogen phosphate particles in the surface conditioner and prevent agglomeration caused by precipitation of the calcium hydrogen phosphate particles. The kind of the tackifier is not particularly limited, and examples thereof include: natural polymers such as proteins, natural rubbers, saccharides (including sugar derivatives), alginic acids, and celluloses; synthetic polymers such as amine resins, carboxylic acid resins, olefin resins, ester resins, urethane resins, PVA, acrylic (methacrylic) resins, and the like, or copolymers obtained by copolymerizing two or more of these resins in combination; various surfactants such as nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants; various coupling agents such as silane coupling agents and titanium coupling agents.

The content of the thickener in the surface conditioner is usually 0.1% by weight or more, and may be 0.5% by weight or more, from the viewpoint of maintaining good dispersibility. The upper limit is usually 20% by weight or less, and may be 10% by weight or less.

The dispersion stability improver is an agent for improving the dispersion stability of the calcium hydrogen phosphate particles in the surface conditioner. Examples of the dispersion stability improver include: and condensed phosphoric acid alkali metal salts such as sodium polyphosphate, potassium polyphosphate, sodium metaphosphate, potassium metaphosphate, sodium pyrophosphate, and potassium pyrophosphate.

The pH adjuster is a reagent for adjusting the pH of the surface adjuster to a predetermined range. The kind of the pH adjuster is not particularly limited, and examples thereof include: phosphoric acid-based alkaline additives such as disodium hydrogen phosphate hydrate, dipotassium hydrogen phosphate, magnesium hydrogen phosphate hydrate, and diammonium hydrogen phosphate; and carbonic acid-based basic additives such as sodium carbonate, potassium carbonate, basic magnesium carbonate hydrate, ammonium hydrogen carbonate, and calcium carbonate.

The pH of the surface conditioner is usually adjusted to 6 or more and 11 or less. The lower limit may be 7 or more, and the upper limit may be 10 or less, and may be 9 or less. Here, the pH in the present specification means a value measured with a commercially available pH meter for a surface conditioner at 25 ℃.

In the surface conditioning step of the present embodiment, a known surface conditioning agent such as a titanium-phosphate colloidal aqueous solution or an aqueous solution containing phosphate ions and zinc ions used in zinc phosphate coating treatment may be used in place of the surface conditioning agent.

< method for producing surface conditioner >

The surface conditioner of the present embodiment can be produced, for example, by the following method: the calcium hydrogen phosphate particles and a dispersant to be mixed as needed are mixed in a solvent, the pH of the mixture is adjusted to a predetermined pH by a pH adjuster, the pH-adjusted mixture is wet-pulverized, and then stirred to disperse the calcium hydrogen phosphate particles. In addition, the method can be produced by: calcium hydrogen phosphate particles adjusted to a predetermined particle size in advance and a dispersant mixed as needed are mixed in a solvent, and the pH of the mixture is adjusted to a predetermined pH with a pH adjuster. In the above method, the dispersant and the pH adjuster are mixed with the calcium hydrogen phosphate particles before wet grinding, but either one may be mixed with the calcium hydrogen phosphate particles before wet grinding, and the other may be mixed with the calcium hydrogen phosphate particles after wet grinding. Further, the dispersant and the pH adjuster may be mixed with the calcium hydrogen phosphate particles after wet grinding.

The order of adding the raw materials to the solvent is not particularly limited, and calcium hydrogen phosphate, the dispersant and the pH adjuster may be added together, or calcium hydrogen phosphate may be added to the solvent to which only the dispersant has been added, and the pH adjuster may be added as needed.

The wet pulverization for adjusting the particle size can be carried out using, for example, a bead mill, but is not limited thereto. The pulverization time is not particularly limited, and may be carried out until the particle size becomes a desired particle size.

Examples

The present invention will be described in further detail below with reference to examples.

< magnesium Material >

In this example, a pure magnesium plate having a purity of 99.9% or more was used.

< production of magnesium Material with coating >

(pretreatment)

The surface of the pure magnesium plate was subjected to degreasing treatment by spraying an alkaline degreasing agent [ FINE CLEANER MG110E (manufactured by parkerising corporation, japan) mixed with an aqueous solution of water so as to be 30g/L ] at 65 ℃ for 120 seconds, and then washed with water. Next, the surface of the degreased pure magnesium plate was physically polished with sandpaper while pouring deionized water, and then washed with deionized water and dried with hot air.

The pretreated pure magnesium plate was subjected to the following steam treatment, surface conditioning treatment, chemical conversion treatment, and apatite conversion treatment in this order, and test pieces of examples 1 to 5 were produced.

(steam treatment)

The pretreated pure magnesium plate was subjected to steam treatment at the temperature and time shown in table 1 using an autoclave. Next, the pure magnesium plate after the steam treatment was taken out, washed with deionized water, and hot-air dried, thereby producing a pure magnesium plate having a coating film containing magnesium hydroxide.

[ Table 1]

Test piece	Temperature (. degree.C.) for steam treatment	Water vapor treatment time (minutes)
			Example 1	120	60
Example 2	125	180
			Example 3	140	60
Example 4	120	60
			Example 5	140	60

< surface preparation treatment >

The surface conditioning treatment was performed by immersing a pure magnesium plate having a coating film containing magnesium hydroxide in a surface conditioning agent at 25 ℃ for 30 seconds. In addition, the surface conditioner was prepared in the following manner.

1 part by weight of carboxymethyl cellulose was dissolved in 55 parts by weight of deionized water. After stirring a mixture in which 24 parts by weight of monetite or brushite was added to the dissolved material, wet pulverization was performed using a dinor Mill (Dyno Mill) (basic glass beads having a diameter of 1 mm). The particle size distribution of the solid content in the pulverized mixture (suspension having a solid content concentration of 30%) was measured using a Maciker (Microtrac) particle size analyzer UPA-EX150 manufactured by Nikkiso K.K., to determine D₅₀And D₉₀. As a result, D₅₀0.45 μm, D₉₀And was 0.9 μm.

Sodium pyrophosphate and trisodium phosphate were added to the suspension to give final concentrations of 250ppm and 200ppm, respectively, to prepare a surface conditioner.

< chemical conversion treatment >

The surface-treated pure magnesium plate having a coating film containing magnesium hydroxide was immersed in a chemical conversion treatment agent at 50 ℃ for 5 minutes to be subjected to chemical conversion treatment. Next, the pure magnesium plate was washed with deionized water and hot air-dried, thereby producing a pure magnesium plate in which a film containing calcium hydrogen phosphate was formed on the film containing magnesium hydroxide. In addition, the above chemical conversion treatment agent was prepared in the following manner.

After 75% phosphoric acid and calcium nitrate tetrahydrate were dissolved in deionized water to give final concentrations of 7g/L and 12g/L, respectively, the pH was adjusted to 3.5 with sodium hydroxide to prepare a chemical conversion treating agent.

< apatite conversion treatment >

A pure magnesium plate material having a coating film containing magnesium hydroxide and a coating film containing calcium hydrogen phosphate was immersed in each alkaline aqueous solution at a predetermined treatment temperature and treatment time as shown in table 2, and subjected to alkali treatment. Then, the pure magnesium plate was washed with deionized water and hot-air dried, thereby producing a coated pure magnesium plate in which part or all of calcium hydrogen phosphate on the surface of the coating containing calcium hydrogen phosphate was replaced with hydroxyapatite and/or hydroxyapatite carbonate (a pure magnesium plate having a coating containing magnesium hydroxide, a coating containing calcium hydrogen phosphate and hydroxyapatite and/or hydroxyapatite carbonate; test pieces of examples 1 to 5).

[ Table 2]

Test piece	Alkaline aqueous solution	Concentration of alkaline aqueous solution (g/L)	Treatment temperature (. degree.C.)	Treatment time (minutes)
					Example 1	Sodium hydroxide	40	60	1
Example 2	Sodium carbonate	50	80	5
					Example 3	Sodium carbonate	15	90	5
Example 4	Potassium carbonate	100	80	5
					Example 5	Potassium hydroxide	50	60	1

As a comparative example, a pure magnesium plate material (test piece of comparative example 1) was prepared, which had been subjected to only a pretreatment. In addition, the mixture contained 50mM Ca-EDTA and 50mM KH₂PO₄1/40 aqueous solution of 1N-NaOH was added to the aqueous solution of (1) to adjust the pH to 6.4, and the pretreated pure magnesium plate was immersed at 95 ℃ for 8 hours in the resulting mixed solution, to prepare a further pure magnesium plate (test piece of comparative example 2) which had been subjected to chemical conversion treatment. Further, the concentration of the compound was 50mM Ca-EDTA and 50mM KH₂PO₄1/20 aqueous solution of 1N-NaOH was added to the aqueous solution of (1) to adjust the pH to 7.3, and the pretreated pure magnesium plate was immersed at 95 ℃ for 8 hours in the resulting mixed solution, to prepare a further pure magnesium plate (test piece of comparative example 3) which was subjected to chemical conversion treatment.

< identification of involucra crystal system >

The films formed on the surfaces of the test pieces of examples 1 to 5 and comparative examples 1 to 3 were measured by X-ray diffraction method, and the crystal systems thereof were identified. As a result, crystalline magnesium hydroxide and calcium hydrogen phosphate crystals were detected from the test pieces of examples 1 to 5. Hydroxyapatite crystals were detected from the test pieces of examples 1 and 5, and hydroxyapatite crystals were detected from the test pieces of examples 2 and 4. Hydroxyapatite crystals and hydroxyapatite carbonate crystals were detected from the test piece of example 3. It was confirmed that the test pieces of examples 1 to 5 had a film containing calcium hydrogen phosphate formed on a film containing magnesium hydroxide, and a film containing hydroxyapatite and/or hydroxyapatite formed on the film containing calcium hydrogen phosphate. On the other hand, none of the crystals was detected from the test piece of comparative example 1, and crystalline magnesium hydroxide and hydroxyapatite crystals were detected from the test pieces of comparative examples 2 and 3.

< evaluation of Corrosion resistance >

The test pieces of examples 1 to 5 and comparative examples 1 to 3 were immersed in an aqueous solution containing ions at predetermined concentrations shown in Table 3 at 38 ℃ for 24 hours. Next, after washing with deionized water and hot air drying, the projected area of each test piece irradiated with light was measured. After the measurement, the area of disappearance was obtained by comparing the areas before and after the immersion treatment of the aqueous solution, and the corrosion resistance was evaluated based on the following evaluation criteria. The results are shown in Table 4.

[ Table 3]

Coordinating ionic species	Ion concentration (mol/L)
		Na⁺Ion(s)	0.14
K⁺Ion(s)	0.006
		Ca²⁺Ion(s)	0.0013
Mg²⁺Ion(s)	0.0008
		Cl^-Ion(s)	0.14
HCO₃ ^2-Ion(s)	0.004
		HPO₄ ^2-Ion(s)	0.0008

(evaluation criteria)

And 5, dividing: the vanishing area is 0.

And 4, dividing: the disappearance area is less than 5%.

And 3, dividing: the disappearance area is 5% or more and less than 50%.

And 2, dividing: the disappearance area is 50% or more and less than 90%.

1 minute: the disappearance area is 90% or more.

[ Table 4]

Test piece	Corrosion resistance
		Example 1	4
Example 2	5
		Example 3	5
Example 4	4
		Example 5	5
Comparative example 1	1
		Comparative example 2	2
Comparative example 3	3

It should be noted that although the present invention has been described in detail with reference to specific examples, it is obvious that various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A magnesium-containing metal material with a involucra, which is characterized in that,

the magnesium-containing metal material is formed by magnesium or magnesium alloy, and has a first film containing magnesium hydroxide on the surface, a third film containing hydroxyapatite and/or hydroxyapatite carbonate on the first film, and a second film containing calcium hydrogen phosphate between the first film and the third film.

2. The filmed magnesium-containing metallic material according to claim 1, wherein,

the second coating is a coating comprising monetite and/or brushite.