KR940009674B1 - Metal particle - Google Patents

Abstract

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Description

Metal powder

The present invention relates to metal powders, in particular metal pigments.

Generally metal powders such as zinc powder, iron powder, stainless steel powder, copper-zinc-nickel alloy powder, resin plated with metal or glass powder are corroded in the presence of water, oxygen or electrolyte ions. Therefore, metal powder must be handled with care. For example, they are stored in a nitrogen blanket or organic solvent to protect them from corrosion conditions. If the metal powder has a high corrosion rate, hydrogen gas is difficult to treat. In addition, if the metal powders are body-shaped, they are corroded by penetration of water, oxygen or electrolyte into the coating, resulting in poor coating.

In order to prevent corrosion, it has been proposed to contact the metal powder with chromic acid hydrochloric acid. The function of chromate ions is twofold. A chromate ion (CrO ₄ ^2-), and the function of the oxidizing agent to form a stable gamma (gamma) -Fe ₂ O ₃ reacts with the metal atom such as Fe, and one chromate ions are reduced as a function of the coating it is not the case to form an oxide Grom, for example, Cr ₂ O ₃ to be coated on the metal surface. According to the above two functions, a physical protective film is formed on the metal surface to have excellent corrosion protection.

However, chromium (VI), which has a high anti-corrosion property, is toxic to the human body, and accordingly some regulations in Japan greatly limit its use. Therefore, much effort has been made to develop corrosion inhibitors that are not toxic or less toxic to the human body. For example, phosphate materials, in particular zinc phosphate, silica phosphate, concentrated aluminum phosphate, etc. are being studied and some of them are commercially available. However, phosphate materials only have a coating function, so they react with metals to produce materials that protect the metal substrate, but they do not have the function of oxidants. Phosphate materials have poor corrosion protection properties compared to the chromate ions described above.

The inventors have proposed that the supplementary oxidant function of the phosphate material is complemented with soluble ions of vanadium (see Japanese Patent Application No. 204794/1986). We have also developed a new surface treatment process for metal powders.

The present invention provides a metal powder that is surface treated with an aqueous solution containing phosphate ions, soluble vanadium and oxygen and has a maximum size of 1 mm or less.

Soluble vanadium ions complement the oxidant's lack of phosphate ions. The vanadium ions form redox couples under corrosion conditions involving water and oxygen, and the redox couples exhibit significant redox potentials where the oxidant function is satisfied. Also as described above, the phosphate ions form a coating FePO ₄ under corrosive conditions, thus providing a coating function. Therefore, the two kinds of ions are indispensable for implementing the present invention, and the effect of the present invention is not satisfied even without one of the two ions.

Soluble vanadium ions used in the present invention

등의 3가, 4가 및 5가 바나듐 원소를 갖는 단량체 또는 중합체 이온이다. 본직적으로 상기 바나듐 이온들은 바나듐 이온, 바나딜 이온, 오르토바나딘산염 이온 및 축합 바나딘산염이온으로 분류된다. 바나딘산염 이온 및 축합 바나딘산염 이온이 바람직하다. 상기 두 이온종은 일반적으로 공지의 기술처럼 혼합물로서 수용액에서 존재한다. pH가 중간 부근일 때(5~9의 범위내)오르토 바나딘산염 이온이 수용액에서 서로 축합되므로, 축합 바나딘산염이온이 용액에서 우세하며 오르토 바나딘산염 이온은 미량 존재한다. 대표적인 축합 바나딘산염이온으로서 예를 들면 피로바나딘산염이온, 메타바나딘산염이온, 트리바나딘산염이온, 테트라바나딘산염이온, 헥사바나딘산염이온, 데카바나딘산염이온 등이 있다.

And trivalent, tetravalent and pentavalent vanadium elements. In essence, the vanadium ions are classified into vanadium ions, vanadil ions, orthovanadate ions and condensed vanadate ions. Preference is given to vanadate ions and condensed vanadate ions. The two ionic species are generally present in aqueous solution as a mixture, as is known in the art. Since the ortho vanadate ions are condensed with each other in an aqueous solution when the pH is near (in the range of 5 to 9), the condensed vanadate ions predominate in the solution and trace amounts of ortho vanadate ions are present. Representative condensed vanadate ions include, for example, pyrovanadate ions, metavanadate ions, trivanadate ions, tetravanadate ions, hexavanadate ions, decavanadate ions and the like.

Examples of phosphate ions include orthophosphate ions, pyrophosphate ions, tripoly, phosphate ions, highly condensed phosphate ions, trimetaphosphate ions, tetramethate ions or highly condensed metaphosphate ions. Phosphate ions are present in aqueous solutions in various forms due to their degree of condensation and pH. In general, phosphate ions are condensed in aqueous solutions.

In order to provide the soluble vanadium ions and phosphate ions, an ion carrier such as an ion-exchange resin or an inorganic ion exchange material (eg hydrotalcite) may be made to absorb the ions. Corrosion inhibitors prepared by mixing vanadium ions or by firing or applying phosphate and soluble vanadium ions may be added to the aqueous solution to extract phosphate ions and soluble vanadium ions. Japanese Patent Application No. 36191 /

1987, 36192/1987, 36189/1987 and 16190/1987.

It is necessary for the presence of oxygen in the aqueous solution. It does not always provide oxygen to the aqueous solution. Since the water contains dissolved oxygen, it is sufficient to use neutral or deionized water. If the treatment is carried out in the absence of oxygen, it is necessary to introduce oxygen into the aqueous solution.

The method of surface-treating a metal powder with an aqueous solution containing soluble vanadium ions, phosphates and oxygen may consist of spraying the aqueous solution onto the metal powder suspended in air. In order to effectively prevent agglomeration of the powder and to perform a uniform treatment, it is preferable to impregnate the metal powder in the aqueous solution, especially under the conditions of mixing or ultrasonic vibration.

Various forms of metal powders can be used in the present invention. Examples are spheres, flakes, hollow shapes, or intangibles. The maximum size of the powder is 1 mm or less, preferably in the range of 1 to 100 microns. The powder may be made of zinc, zinc / iron alloys, aluminum, aluminum alloys, steel staines, steel copper, copper / zinc / nickel alloys, resins with metal surfaces of copper surfaces or glass powders and the like. The powder is preferably a metal pigment. More preferably, it is an aluminum pigment in flake form. In general, aluminum pigments react with water or many electrolytes in paints, causing their gloss to be severely degraded and blackened, thus making them unsuitable as pigments. The aluminum pigment treated as disclosed in the present invention has excellent gloss retention and improves the wettability of the binder component in the paint.

If the aqueous solution for treatment contains soluble vanadium ions, phosphate ions and oxygen, the treatment conditions are not limited. The treatment condition is preferably in the range of pH5 to pH9. The amounts of soluble vanadium ions and phosphate ions are respectively 0.001 to 0.1 mol / liter, preferably 0.05 to 1 mol / liter. Outside the above range, the technical effect of the present invention is reduced. The temperature at the time of treatment is not particularly limited. When the temperature is high, the processing time is shortened.

The aqueous solution for treatment may further include other additives such as surface active agents and cations such as calcium ions and magnesium ions.

The surface treated metal powder has a very thin film on the surface, a so-called passive film, but retains its characteristics as a powder. The powder is easy to handle and can be stored in air. By carrying out the treatment of the present invention, it is possible to prevent the color change of the metal powder for a long time. By carrying out the treatment of the present invention, the wettability to the resin binder can be increased and the time required for the dispersing process can be saved.

The invention is illustrated by the following examples, without however limiting the invention.

[Examples 1-4 and Comparative Examples 1-3]

This example shows the technical effect of the treatment of the present invention.

0.05 mol of orthophosphoric acid is added to 0.05 mol of an aqueous solution of sodium orthovanadate, and the pH is adjusted to 7 with sodium hydroxide to form an aqueous solution A for treatment. Another aqueous solution B containing only 0.05 moles of orthophosphoric acid is prepared in a similar manner. The metal powders shown in Table 1 were immersed in aqueous solutions A and B and deionized water for 1 hour, then washed with deionized water and dried. The powder obtained is left at 40 ° C. for 7 days in air and the color is visually evaluated. The results are shown in Table 1.

TABLE 1

[Examples 5-7]

An aqueous solution containing sodium phosphate and vanadium pentoxide is surface treated with a copper powder having an average size of 2 micrometers while varying the pH of the solution. Treatment and evaluation are generally performed in the same manner as in Examples 1 to 4. The results are shown in Table 2.

TABLE 2

[Examples 6-12]

The test is generally carried out in the same manner as in Examples 1-4 except that copper particles having an average size of 2 micrometers are used and the concentrations of phosphate and vanadate ions are varied. The results are shown in Table 3.

TABLE 3

[Examples 13 to 19]

The present invention exhibits the technical effect of aluminum flake pigments surface treated according to the present invention.

The aluminum flake pigment is generally surface treated in the same manner as in Examples 1-4, except that the pH of the aqueous solution and the concentrations of phosphate ions and vanadate ions are changed as shown in Table 5. The obtained aluminum flake pigment is sieved with an aqueous coating, the preparation of which is described after Table 4. The amount of hydrogen gas generated from the paint is measured by collecting it in a flask.

In addition, the aqueous paint is poured into the test tube and left at 50 ° C. for 10 days. The precipitated aluminum flakes are visually observed. In addition, the aqueous coating is spray-coated as described in the coating test following Table 4, and the gloss of the cured coating is visually evaluated.

Evaluation is carried out as follows; Aluminum flake pigments coated with conventional organic phosphates are standard. Compared to the above, good, excellent, bad, very bad is determined.

Table 4 shows the results of the test.

TABLE 4

Manufacture of paint

[Production of Polyester Resin]

130 parts by weight of bishydroxyethyl taurine, 134 parts by weight of neopentyl glycol, 236 parts by weight of azelaic acid, 186 parts by weight of phthalic anhydride in a 2-liter flask equipped with a stirrer, a nitrogen-introducing tube, a thermostat, a condenser and a decanter; Add 27 parts by weight of xylene, and start the reaction by heating. The water produced by the reaction is azeotropically distilled with xylene.

The mixture is heated at 190 ° C. for at least about 2 hours after commencing reflux, mixing is continued and distillation is continued until the acid value corresponding to the carboxylic acid is 145. The mixture is then cooled to 140 ° C. and 314 parts by weight of Cardura E10 (glycidyl ester of Versartic acid available from Cell Chemical Company) is added while maintaining at 140 ° C. for 30 minutes. Mixing is continued for 2 hours to complete the reaction. The obtained polyester resin has an acid value of 59, a hydroxyl value of 90 and Mn 1054.

[Production of Resin Powder]

282 parts by weight of deionized water, 10 parts by weight of the obtained polyester resin and 0.75 parts by weight of dimethylethanolamine were added to a 1 liter reaction vessel provided with a stirrer, a condenser and a temperature control mechanism to form a mixture. A solution containing 4.5 parts by weight of azobiscyanovaleric acid, 45 parts by weight of deionized water and 4.3 parts by weight of diethylethanolamine was added to the mixture, and 70.7 parts by weight of methyl methacrylate and 94.2 parts by weight of n-butyl acrylate. Part, a solution containing 70.7 parts by weight of styrene, 30 parts by weight of 2-hydroxy ethyl acrylate and 4.5 parts by weight of ethylene glycol dimethyl acrylate is added dropwise over 60 minutes. After the addition, 1.5 parts by weight of azobiscyanovaleric acid, 15 parts by weight of deionized water and 1.4 parts by weight of dimethylethanol amine were added and mixed at 80 ° C. for 60 minutes to prepare a nonvolatile 45%, pH 7.2, viscosity 92 cps (25 ° C.) and An emulsion having a powder size of 0.165 microns is obtained. The emulsion is spray dried to obtain a resin powder having a powder size of 0.3 micron. 100 parts by weight of the powder is dispersed in 200 parts by weight of xylene to obtain a xylene dispersion.

[Production of Resin for Metallic Paint]

76 parts by weight of ethylene glycol monobutyl ether, and 61 parts by weight of monomer solution (45 parts by weight of styrene, 63 parts by weight of methyl methacrylate, 2-hydroxyethyl methacrylate) in a reaction vessel equipped with a stirrer, a thermostat and a condenser 48 parts by weight, 117 parts by weight of n-butyl acrylate, 27 parts by weight of methacrylic acid, 3 parts by weight of lauryl mercaptan and 3 parts by weight of azobisisobutyronitrile) were added at 120 ° C. and mixed for 1 hour. do. 28 parts by weight of dimethylethanol amine and 200 parts by weight of deionized water are added to the mixture to obtain an acrylic varnish having 50% non-volatile and Mn 6,000. The OH value of the resin was 70 and the acid value was 58.

[Manufacture of Metallic Paints]

A mixture consisting of 140 parts by weight of the resin varnish described above, 30 parts by weight of the resin dispersion, 10 parts by weight of aluminum pigment and 30 parts by weight of Symel 30 as a replacement binder was added to the fourth Ford Cup (20 ° C) with deionized water. Dilute to 25-30 seconds to form a metal paint.

[Production of Transparent Paint]

65.8 parts by weight of n-butyl acrylate, 11.8 parts by weight of methyl methacrylate, 16.2 parts by weight of hydroxyethyl methacrylate, 6.1 parts by weight of methacrylic acid and 5 parts by weight of azobisisobutyronitrile, Preparation of Resin for Paint) The polymer is prepared as described. The polymer is neutralized with dimethylethanolamine and then diluted with water to give a resin varnish that is non-volatile 50%.

To obtain a resin varnish, a crosslinking agent (hexamethoxymethylolmelamine commercially available from Mitsui Toatsu Company) was added at a solid / resin ratio of 70/30, and 30 to 35 of the fourth pod cup. Dilution to second yields an aqueous clear coating.

[Painting test]

Metallic paint is sprayed onto a medium-coated steel panel at a thickness of 20 microns at 23 ° C. and 60% relative humidity. On top of that, the transparent paint is sprayed to a thickness of 30 microns under the above-described conditions. In the former case, the coating is carried out in two steps at intervals of one minute and dried at 80 ° C. for five minutes. In the latter case, paint in step 1 and allow to solidify for 7 minutes. The panel to be painted is cured at 150 ° C. for 20 minutes to obtain a sample panel.

Claims (5)

Metal powder having a maximum size of 1 mm or less, surface-treated with an aqueous solution containing phosphate ions, soluble vanadium ions and oxygen. The metal powder according to claim 1, wherein the surface treatment is performed by spraying the aqueous solution on the metal powder or by depositing the metal powder in the aqueous solution. The metal powder according to claim 1, wherein the aqueous solution contains 0.001-0.1 mol / liter of soluble vanadium ions, 0.001-0.1 mol / liter of phosphate ions, and the pH of the aqueous solution is 5-9. The metal powder of claim 1, wherein the metal powder is a metal pigment. The metal powder according to claim 4, wherein the metal pigment is an aluminum flake pigment.