JPS63186777A - Surface treating composition for imparting high corrosion resistance to metallic surface - Google Patents

Abstract

PURPOSE:To form a compsn. for use in coating a metallic surface to give a treated surface having high corrosion resistance and suitability as a ground for coating, by mixing a specified inorg./org. composite reaction product mainly composed of water-dispersible silica and a water-soluble or water-dispersible org. polymer resin with a water-soluble or water-dispersible chromium compd. CONSTITUTION:This surface treating compsn. for imparting high corrosion resistance to metallic surfaces is obtd. by mixing an inorg./org. composite reaction product (hereinafter referred to as silica composite material) composed of water-dispersible silica, a water-soluble or water-dispersible org. polymer resin and a di- or trialkoxy (or alkoxyalkoxy)silane compd. with a water-soluble or water-dispersible chromium compd. Examples of the water-soluble or water- dispersible chromium compd. are chromic anhydride, chromates, dichromates and chromium chromate composed of hexavalent chromium and trivalent chromium or its salts. The chromium compd. is used in an amount ref. not more than 40wt.% based on that of the silica composite material on a solid basis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to adding a water-soluble or water-dispersible chromium compound to an inorganic-organic composite reactant containing water-dispersible silica and an aqueous organic polymer resin as main components. The present invention relates to a metal surface treatment composition for the purpose of applying a mixed composition to a metal surface to provide a treated surface having a high degree of corrosion resistance and coating base properties.

[Problems to be solved by conventional techniques and inventions] Conventionally,
Phosphate treatment or chromate treatment has been used as a general method for a long time for the purpose of imparting corrosion resistance to metals and paint base properties. In addition, recently, 6
Surface treatment agents that do not use chromium compounds, fluorine compounds, phosphoric acid compounds, etc. are being developed. As a surface treatment agent for this purpose, the present applicant has proposed an inorganic-organic composite composition containing water-dispersible silica and an aqueous organic polymer resin as main components (for example, Japanese Patent Publication No. 54-34406,
Special Publication No. 54-34783, Special Publication No. 54-3478
Publication No. 4, Special Publication No. 1983-41711, Special Publication No. 1983
-41712 Publication, Special Publication No. 55-41713,
(Refer to Japanese Patent Publication No. 57-30887, etc.), such a composition can achieve effects comparable to conventional zinc phosphate treatment and chromate treatment, and because it is a water-less coating type, it can save labor in the treatment process. It has been put into practical use as a non-polluting metal surface treatment agent due to its effects such as:

However, the effect is equivalent to or slightly better than conventionally known general surface treatment techniques, and baking is required to form the film, and insufficient curing may affect the water resistance of the film.
It has drawbacks such as poor chemical resistance (for example, alkali resistance, acid resistance, organic solvent resistance, etc.) and requires the installation of a relatively high-temperature baking furnace, which leaves room for further improvement.

[Means for Solving the Problem] Therefore, the present inventors have developed a back surface treatment composition that improves the above-mentioned drawbacks and also provides significantly superior corrosion resistance and coating base properties compared to conventionally known methods. As a result of intensive research, the applicant developed the above-mentioned inorganic-organic composite composition (hereinafter simply referred to as "silica composite").
Furthermore, the film formed by applying a composition containing a water-soluble or water-dispersible chromium compound to the metal surface and drying it is different from the conventional chromate treatment film [for example, two-reactive chromate-based or , silica-chromate (
(see Japanese Patent Publication No. 45-38891), coated waterless chromate systems such as organic resin-chromate (see Japanese Patent Publication No. 56-39393), zinc phosphate treated films,
Compared to the silica composite treated film, the salt spray resistance test (JI
In addition to exhibiting excellent corrosion resistance, which is several times as durable as S-2371), it also exhibits excellent adhesion as a coating base, and it also has a lower temperature than the silica composite treatment previously proposed by the applicant. The present invention was completed by discovering that it can be cured with

Since the composition according to the present invention can be applied and washed without water, there are no problems such as leakage, scattering or drainage of hexavalent chromium, which is a harmful component, or generation of sludge. It has characteristics.

Thus, according to the invention, an inorganic-organic composite reactant consisting of a water-dispersible silica, a water-soluble or water-dispersible organic polymer resin, and a di- or trialkoxy (or alkoxyalkoxy) silane compound has a water-soluble Alternatively, a metal surface treatment composition containing a water-dispersible chromium compound as a mixed metal is provided.

The inorganic-organic composite reactant used in the present invention consists of water-dispersible silica, a water-soluble or water-dispersible organic polymer resin, and a silane compound. It can be obtained by reacting with

The water-dispersible silica used in the present invention is:

It is a so-called colloidal silica with a particle size of 7 to 10
It is preferable to have an extension of 0 m, particularly in the range of 10 to 50 m 4 , and those usually supplied as an aqueous dispersion can be used as they are.

Colloidal silica having a particle size within the above range can be used in the form of an aqueous dispersion, either on the acidic or basic side, and is in the stable range of the target water-soluble or water-dispersible organic polymer resin. It can be selected as appropriate.

That is, as the colloidal silica on the acidic side, for example, the product name Snowtex-0 or Snowtex OL is used.
Non-stabilized silica (pH 2 to 4) commercially available (manufactured by Nissan Chemical Industries, Ltd.) can be used. On the other hand, as colloidal silica on the basic side, there are silicas (pH 8, 4 to 10) stabilized by the addition of trace amounts of alkali metal ions, aluminum ions, ammonium ions, or amines, and the product names are Snowtex 20 and Snowtex C. , Snowtex N (manufactured by Nissan Chemical Industries, Ltd.), and the like.

Further, a colloidal liquid obtained by dispersing commercially available silica fine powder in water as shown below can also be used. Such fine silica powder includes fine particulate silica synthesized by a gas phase method using a silicon tetrachloride compound as a starting material. So-called amorphous silica, such as silica obtained by finely pulverizing silica gel produced by gelation of silicic acid, or silica obtained by dehydrating and drying colloidal silica.
There is porous synthetic silica. For example, Aerosil 200.0x50, TT60, which is indicated by the product name "Aerosil"
0(7) Pure silica and MOX80, MOX170, C
Examples include (7) silica-alumina modified products such as 0K84.

The organic polymer resin that forms the inorganic-organic composite reactant in the present invention includes resins containing hydroxyl groups, carboxyl groups, amine (imino) groups, sulfyl groups, etc. in the molecule, such as acrylic Copolymers, alkyd resins, epoxy resins, fatty acid or polybasic acid-modified polybutadiene resins, methylol group-introduced phenolic resins,
These include alkanolamine-modified polyurethane resins, polyamine resins, amino resins, polycarboxylic acid resins, α-olefin-αΦβ-unsaturated carboxylic acid copolymer resins, mixtures of two or more of these resins, and addition condensates.

Acrylic resins for this purpose include water-soluble or water-dispersible acrylic resins synthesized by solution polymerization, emulsion polymerization, or suspension polymerization using common unsaturated ethylenic monomers, and alkyd resins. It is an acrylic resin modified with resins such as epoxy resin, butadiene resin, urethane resin, phenol resin, and amide resin.

Further, as the alkyd resin, generally known alkyd resins obtained by ordinary synthesis methods can be used. Examples include oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin, styrene-modified alkyd resin, acrylic-modified alkyd resin, epoxy-modified alkyd resin, silicone-modified alkyd resin, oil-free alkyd resin (polyester resin), and the like.

Epoxy resins include fatty acid-modified epoxy resin, polybasic acid-modified epoxy resin, acrylic-modified epoxy resin, alkyd-modified epoxy resin, polybutadiene-modified epoxy resin, phenol-modified epoxy resin, amine-modified epoxy resin, amine-urethane-modified epoxy resin, etc. There is.

Furthermore, in the α-olefin-α-β unyielding carboxylic acid copolymer resin, α-olefins include ethylene, propylene,
Monomers such as butene, butylene, isobutylene and α/β
A copolymer of an unsaturated carboxylic acid with a monomer such as acrylic acid, methacrylic acid, or maleic acid is used, and the amount of carboxyl in the resin is 5 to 40% by weight.

These resins can be used regardless of whether they are anionic, cationic, amphoteric, or nonionic in charge, and can be used in the form of an aqueous solution or an emulsion.

Further, these resins can be used alone or as a mixture of two or more types as required.

Water solubilization or water dispersion of these polymer resins is
Depending on the functional group introduced into the resin skeleton [e.g. hydroxyl group, carboxyl group, ami/(imino) group, sulfide group, phosphine group, etc.], in the case of acidic resins, amine compounds (e.g. monoethylamine aliphatic amines, alkanolamines such as jetanolamine, and cyclic amines such as pyridine), by neutralizing with ammonia water or alkali metal hydroxide, while in the case of basic resins, acetic acid, This can be achieved by neutralization with fatty acids such as lactic acid or mineral acids such as phosphoric acid.

The silane compound as the third component of the silica composite in the present invention functions as a catalyst in the above-mentioned conjugation of silica and organic polymer resin, and also plays an important role as a crosslinking agent for both. .

In order to exhibit such effects, the compound can be appropriately selected from those exemplified below depending on whether the aqueous dispersion of colloidal silica is acidic or basic: For example, Divinyldimethoxysilane, divinyldi-β-methoxyethoxysilane, di(γ-
Glycidoxypropyl)dimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-glycidoxypropyltrimethoxysilane, γ-methacrylicoxypropyltrimethoxysilane, β-(3,4 -epoxycyclohexyl)ethyltrimethoxysilane, N-β(aminoethyl)γ-propylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, etc. can.

In the silica composite of the present invention, the mixing ratio of water-dispersible silica and water-soluble or water-dispersible 11!1 polymer resin is 5:95 to 95:5 in solid weight percentage,
When a coated board using the present composition is subjected to molding process, a range of 20:80 to 50:50 is preferable, and when a coated board is not subjected to forming process, a range of 50:50 to 95:5 is preferable. preferable.

The proportion of the silane compound used as the third component is usually 0.5 to 15%, preferably 0.5 to 15%, based on the total solid weight of the water-dispersible silica and the water-soluble or water-dispersible a-polymer resin. 1 to 10%, and if it is less than 0.5%, the reaction acceleration effect and crosslinking effect due to addition are not clear, and 15% is less than 0.5%.
Even if it is added in excess of %, it cannot be expected that these effects will become even more significant.

In order to produce a silica composite, first, the aqueous dispersion or solution of both the silica and the organic polymer resin are mixed and dispersed, and then a silane compound is mixed with the mixture while stirring thoroughly. This mixture is at room temperature.

A silica composite can be obtained by aging preferably at 10°C or higher; however, in order to obtain a strong film, the mixture should be aged at 50°C or higher at the boiling point (usually 105 to 110°C).
It is desirable to heat continuously at a temperature below
Specifically, the three components are sufficiently bonded by heating at 50 to 90°C. As heating continues, the viscosity of the mixed liquid gradually increases, but eventually it becomes almost constant and no change is observed, so at that point you can mark the end point and stop heating.1Normally, by the time the end point is reached, the viscosity of the mixed liquid is 0. It takes 5-5 hours.

In the present invention, a water-soluble or water-dispersible chromium compound is added as an essential component to the above-mentioned silica composite, and these chromium compounds are mainly hexavalent chromium oxides, and are exemplified below. Examples include compounds.

r Chromation: Chromic anhydride (Cr03), lithium chromate (Li
z Cr04 e 2H20), sodium chromate (Na2Cr04610H20), potassium chromate (
K2 Croa), ammonium chromate ((NH
4) 2 Croa), sodium dichromate (N
a2Cr20. *2H20), potassium dichromate (
K2Cr207), ammonium dichromate ((NHa
) 2 Crz 07 ) etc.

7 Chromium strontium dichromate (SrCroa), barium chromate (BaCroa), lead chromate (PbC)
rOa), calcium chromate (CaCrOa), basic zinc chromate (ZnCr04 e 4Zn (OH)
2), basic potassium zinc chromate (K20 fist 4Zn
O-Fist 4Cr 03” 3H20), L/-/
Silicochromate (Sin□ 5Pbcr04)
Such.

Chromium dichromate is a composite compound consisting of hexavalent chromium and trivalent chromium, and is the most effective chromium compound in the present invention. The reason for this is that it combines the anticorrosion effect of chromic acid derived from hexavalent chromium, the effect of accelerating crosslinking and hardening of the silica composite due to trivalent chromium, and the effect of adhesion to metal surfaces.

The method for producing such a compound is not particularly limited. ; aromatic polyhydric alcohols such as hydroquinone and catechol; polysaccharides such as sucrose and glucose; aldehydes such as formalin; and inorganic compounds such as hydrogen peroxide and hydrazine. It will be done. The amount of these reducing agents to be used is determined stoichiometrically depending on the desired amount of hexavalent chromium in the chromium chromate, and the reduction reaction can be carried out by heating. As the chromium compound suitable for this purpose, it is preferable to use chromic anhydride containing no soluble metals.

The blending amount of the chromium compound in the present invention is 40% by weight or less in terms of the solid content of the silica composite, preferably 0.1 to 5% for water-soluble chromium compounds and chromium chromate compounds.
% by weight, and 2 to 40% by weight for water-dispersible chromium compounds. If it is added at a high concentration exceeding this concentration range, aggregates will form locally, making it impossible to obtain a uniform composition, and the water resistance of the film will decrease, causing blistering, and there is a risk that hexavalent chromium may be eluted. There is. On the other hand, if the amount added is low in concentration, a sufficient anticorrosive effect cannot be obtained.

Although the effect of the excellent corrosion resistance of the composition of the present invention has not yet been fully elucidated, the following mechanism of action is expected. That is, the formation of an un(@-formed film on the metal surface by the hexavalent chromium compound in the composition,
For example, after applying the composition of the present invention to a metal plate, it can be treated with an organic solvent (methylene chloride) and ion-exchanged water. When the coating film was removed by repeated treatment and the metal surface was observed by fluorescence X-ray analysis, X-ray microanalyzer analysis, photoelectron spectroscopy, etc., elements of chromium and silicon were detected. This suggests that when the composition of the present invention is applied to metal, chromium and silicon (derived from colloidal silica and silane compounds) are selectively oriented on the metal surface to form a film.

In addition, during the hardening film formation process of the treated plate coated with the composition of the present invention, trivalent chromium and functional groups (hydroxyl groups) in the silica complex generated by the oxidation-reduction reaction of trivalent chromium and hexavalent chromium in the chromium compound. , carboxyl group, carbonyl group, amino group, etc.), the formed coating film is densified and becomes a barrier film that blocks corrosion-forming substances. It is thought that this effect shows excellent corrosion resistance.

The composition of the present invention may also be prepared by mixing resins compatible with the composition of the present invention among conventionally known water-soluble or water-dispersible resins, such as aminoplast resins and epoxy resins, as needed. You can also adjust the properties of Also,
Low-temperature curing is made possible by the combined use of chelate compounds of titanium, zirconium, aluminum, etc. as described in Japanese Patent Publication No. 55-41711, metal salts as described in Japanese Patent Application Laid-Open No. 55-62971, and the like. moreover,
Coating compositions with optical opacities obtained by dispersing pigments in the composition of the present invention; Colored transparent compositions obtained by dissolving dyes; commonly known anticorrosion pigments (e.g. red lead, suboxide Lead, cyanamide lead, calcium leadate, basic lead sulfate, zinc phosphate, zinc molybdate, potassium molybdate, barium metaborate, etc.) and rust inhibitors (phenolic carboxylic acids, organic phosphoric acids, phytic acid, urea derivatives) Electrolytic protection compositions containing metal powders such as zinc and aluminum dispersed in them: Improving the electrical conductivity of the film and improving its suitability for electrodeposition coating and welding. Conductive substances (e.g.
Zinc powder, aluminum powder, iron phosphide (Fe2F)
.

Zinc oxide (ZnO-Al doped), tin oxide-titanium oxide (Sn02-Ti02), tin oxide-barium sulfate (
S n02-BaSO4), semiconductor oxides such as oxidized Ni/Kel-alumina (NiO□-A1203), etc.); when adopting a low energy curing method, the method described in Japanese Patent Publication No. 55-41712 A composition of a photosensitizer such as zinc oxide, anatase-type titanium oxide, or titanic acid as described above and an oxyacid salt such as molybdenum or vanadium,
It can be used as a composition for curing with ultraviolet light or electron beam. Furthermore, in order to provide the scratch resistance required in coating systems used for roofing materials, etc., it is also possible to create a composition to which silica, alumina, clay, etc. are added.

The composition of the present invention may be applied by a conventionally known method.
For example, brush coating, spray coating, roll coating, dip coating, and other methods can be used, so it can be applied to a wide range of applications, including coil coating, complex shapes, and outdoor structures.

In order to cure the composition of the present invention, depending on the type and properties of the monomers constituting the organic polymer resin, for example, room temperature to
It may be cured by natural drying or heating at a temperature of 00° C. for about 2 seconds to 30 minutes.

Furthermore, when the object to be coated is electrically conductive and the free functional groups of the composition of the present invention are charged either negatively or negatively, it is also possible to apply an electrodeposition coating method. In particular, in anodic electrodeposition treatment, chromic acid selectively reaches the metal interface and forms an excellent anti-corrosion film. In addition, if an organic polymer resin with unsaturated double bonds is used, it can be cured using an ordinary electron beam irradiation device (100
~300 KeV, 30-100 mA) or an ultraviolet irradiation device (30-120 W/am high-pressure mercury lamp). Furthermore, since the reduction reaction of chromic acid in the composition of the present invention is promoted by ultraviolet rays and electron beams, the crosslinking reaction of the silica composite can also be promoted by the production of trivalent chromium.

The objects to be coated for carrying out the present invention include ordinary metals (
For example, steel and alloy steel, aluminum, aluminum alloy (alloy metals such as magnesium, chromium, zinc, silicon, nickel, copper, manganese, etc.), aluminum plated steel, aluminum alloy plated Steel plates, zinc, zinc alloys (alloy metals such as iron, cobalt, nickel, chromium, molybdenum, tin, manganese, tungsten, aluminum), galvanized steel, zinc alloy plated steel, tin plated steel, lead-tin alloy, etc. , or metals with multiple layers of these metals or metals such as nickel and chromium. In addition, for metal materials that have been subjected to generally known metal surface treatments for the purpose of rust prevention and providing paint base properties, such as iron and zinc, iron phosphate, zinc phosphate, chromate (reactive type If the composition of the present invention is applied to surface-treated metal materials such as chromate, anodic oxidation, and boehmite for aluminum, such as composite oxide films, etc., even better corrosion resistance can be imparted In particular, when applied on a chromate-based surface treatment, it forms a film that exhibits not only water resistance, humidity resistance, and alkalinity, but also outstanding corrosion resistance.

The composition of the present invention can be made into a single composition or a composition in which two or more kinds are mixed as necessary. It can be applied as a surface treatment agent, cosmetic, stain resistant, flame retardant, and scratch resistant paint.

Examples and comparative examples are shown below. These examples are intended to explain the invention in more detail and are not intended to limit the scope of the invention. 0 parts and % indicate parts by weight and % by weight.

Chrome Chrome.

Dissolve 44.8 g of chromic anhydride in 150 g of water, add 3.9 g of wheat starch, and continue for 30 min. The ratio was 0.68:1.

Put 180 parts of inpropyl alcohol into a four-piece flask equipped with a thermometer, stirrer, condenser, and dropping funnel, and after purging with nitrogen, adjust the temperature inside the flask to about 85°C, and add 140 parts of ethyl acrylate, A monomer mixture consisting of 68 parts of methyl methacrylate, 15 parts of styrene, 15 parts of N-n-butoxymethylacrylamide, 38 parts of 2-hydroxyethyl acrylate, and 24 parts of acrylic acid,
2,2'-azobis(2,4-dimethylwellonitrile)
0, which is added dropwise over a period of about 2 hours with a catalyst consisting of 6 parts.
After the dropwise addition was completed, the reaction was continued for another 5 hours at the same temperature to obtain a colorless and transparent resin solution with a polymerization rate of approximately 100%, a solid content of approximately 63%, and an acid value of 67.

12' Put 100 parts of linseed oil, 70 parts of trimethylolpropane, and 0.07 parts of litharge into an Alkis flask, heat to 220°C in a nitrogen stream while stirring, and react at this sensitivity for 30 minutes. Cool, and when the temperature reached 700C, add 110 parts of phthalic anhydride and 13 parts of Kijirole, heat to 220°C while stirring, and react under reflux of Kijirole.
The reaction was terminated when the acid value fell to 15, and when cooled to 80°C, 38 parts of pheasant roll and 32 parts of ethylene glycol monoethyl ether were added to prepare an alkyd resin solution with a solid content of about 70% and an acid value of 15. Obtained.

3. Epoxy Bisphenol A type epoxy resin with epoxy 1i950 (trade name: Ebicoat 1004, manufactured by Shell Chemical Co., Ltd.) 62 parts, linseed oil 19 parts, tung oil 19 parts, xylene 3
Place the sample in a flask and gradually heat it while passing nitrogen through it.
After raising the temperature to 240°C, the temperature was heated under reflux for 2 hours, then cooled, and when the temperature had dropped to 70°C, 40 parts of ethylene glycol monoethyl ether was added to give a solid content of approximately 70% and an acid value of 54. A fatty acid-modified epoxy resin solution was obtained.

Silica-1 108 parts of dimethylaminoethanol was mixed with 500 parts of the acrylic copolymer resin solution obtained in Synthesis Example 1, and after adding water, the mixture was sufficiently stirred to form an acrylic copolymer with a solid content of 20% and a pH of about 10. An aqueous polymeric resin dispersion was obtained. 375 g of this aqueous dispersion was placed in a flask, and 125 g of colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: "Snowtex NJ") with a solid content of 20% was added dropwise over about 10 minutes while stirring thoroughly at room temperature. After the completion of the 0 dropwise addition, γ-methacryloxybrobyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name rKBM503J) 2. A milky white water-dispersible silica composite composition 1 was obtained by holding the reaction mixture for a certain period of time.

Silica 2 20 parts of triethylamine was mixed with 500 parts of the oil-modified alkyd resin solution obtained in Synthesis Example 2, and after water was added, the mixture was sufficiently stirred to obtain an aqueous alkyd resin dispersion with a solid content of 20% and a pH of about 10. Ta. Pour 200 g of this aqueous dispersion into a flask, and stir thoroughly at room temperature until the solid content reaches 20.
% of colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name "Snowtex CJ") was added dropwise over a period of about 10 minutes.After the W4 was finished, vinyl tris (β-methoxyethoxy) silane (manufactured by Shin-Etsu Chemical Co., Ltd., Product name rKBc100
3'') was added dropwise and mixed under stirring, and then heated to 85° C. and kept at the same temperature for 2 hours to react, to obtain a milky white water-dispersible silica composite composition 2.

Silica 3 By mixing 70 parts of diethylaminoethanol with 500 parts of the fatty acid-modified epoxy resin solution obtained in Synthesis Example 3, and stirring thoroughly after adding water, the solid content was 20% and the pH was about 1.
A fatty acid-modified epoxy resin aqueous dispersion of 0 was obtained. 300 g of this aqueous dispersion was placed in a flask, and 200 g of 20% colloidal silica (manufactured by Nissan Chemical Industries, Ltd., trade name: "Snowtex NJ") was gradually added dropwise for 11 minutes while thoroughly stirring at room temperature. After the completion of 9 drops. , γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name rK
BM403J) 2.4gt was mixed dropwise under stirring, then heated to 85°C and kept at the same temperature for 2 hours to react, to obtain a milky white water-dispersible silica composite composition 3.

400 g of ethylene-acrylic acid copolymer resin (manufactured by Nippon Polyurethane ■, trade name "Niraporan 3202J") with a solid content of 20% and a pH of about 9.8 was placed in a flask, and the mixture was thoroughly stirred at room temperature. Colloidal silica with a solid content of 20% (manufactured by Nissan Chemical Industries, trade name: "Snowtex NJ") 1
After the completion of the 0 dropwise addition, 1.5 g of N-P (aminoethyl) γ-propylmethyl dimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name rKBM602J) was added dropwise and mixed with stirring, and then heated to 85°C. The mixture was kept at the same temperature for 2 hours to react, thereby obtaining a milky white water-dispersible silica composite composition 4.

Example 1 A metal surface treatment composition of the present invention was prepared by adding 2 parts of chromic anhydride to 100 parts (solid content) of the silica composite composition 1 synthesized above and stirring and mixing.

Next, a dry film was applied to a hot-dip galvanized steel plate (zinc coating amount: 100 g/rn' on one side) that had been cathodic electrolytically degreased with the above composition (5% sodium carbonate aqueous solution, 75°C, electrolytic current density 8 A/drn', energization for 10 seconds). It was applied to a thickness of 2 microns and baked with hot air at 100°C for 30 seconds. When this coated plate was subjected to a salt spray test, no spontaneous rust was observed even after 480 hours as shown in Table 2.

Example 2-i.

100 parts of the silica composite composition synthesized above (solid content)
A metal surface treatment composition of the present invention was obtained in the same manner as in Example 1 by adding the chromium compounds shown in Table 1 below. Using this material, a coated plate was prepared in the same manner as in Example 1, and a salt spray test was conducted. The results are shown in Table 2 below.

Table 1 Examples 11 to 20 The composite surface-treated plates prepared in Examples 1 to 10 were coated with aminoalkyd paint (manufactured by Kansai Pain II, trade name "Amilac") and heated at 120°C for 20 minutes. A coated plate with a total film thickness of 20 microns was prepared. The corrosion resistance of this coated plate in a salt spray test showed significantly superior performance compared to the current zinc phosphate treated zinc steel plate. The results are shown in Table 3 below.

Examples 21-30 An epoxy primer paint for pre-coated metal (Kansai Paint Hoso, trade name: rKP Color 8470 Primer) was applied to the composite surface treated plates prepared in Examples 1-10, and heated at 210°C for 50 seconds. A coated plate with a dry film thickness of 5 microns was prepared, and then a polyester topcoat (manufactured by Kansai Paint Co., Ltd., trade name rKP Color, 14
70, Blue'') was applied and heated at 220°C for 50 seconds to produce a coated plate with a total dry film thickness of 25 microns. The corrosion resistance of this coated plate in a salt spray test was found to be significantly superior to that of current galvanized steel sheets treated with zinc phosphate and galvanized steel sheets treated with chromate chromate. The results are shown in Table 4 below.

Comparative Examples 1 to 18 To 8 parts (solid content) of the acrylic resin prepared in Synthesis Example 1 of the organic polymer composition, 2 parts (solid content) of melamine resin (trade name "Cynul 303J, manufactured by Cyanamid International, USA)" was added. The mixed composition was coated to a dry film thickness of 2 microns and baked at 180°C for 5 minutes on a galvanized steel sheet (Comparative Example 1). Galvanized steel sheet (Comparative Example 2) prepared in the same manner as Comparative Example 1 except for using a composition containing
2. Synthesis Example 2 was conducted according to Comparative Example 1 using a composition in which 0.5 parts of chromium was added to a composition in which 8 parts of alkyd resin (solid content) and 2 parts of melamine resin (solid content) were mixed. Galvanized steel sheet (Comparative Example 3): Based on Synthesis Example 3, 1 part of basic zinc chromate was added to a composition in which 8 parts of epoxy resin (solid content) and 2 parts of melamine resin (solid content) were mixed. Galvanized steel sheet prepared according to Comparative Example 1 using a composition to which chromium was added (Comparative Example 4) Chromium was added to 10 parts (solid content) of the ethylene-acrylic acid copolymer resin shown in Synthesis Example 4 of Nisilica composite. Galvanized steel sheet prepared according to Comparative Example 1 using a composition to which 0.5 parts of strontium oxide was added (Comparative Example 5); Galvanized steel sheet treated with chromium chromate-silica (treatment agent 2 manufactured by Kansai Paint ■, product) Name: Cosmer 1
504, adhesion i 3200 mg/m') (Comparative Example 6); Based on Synthesis Example 1 of the silica composite described above (zinc plating in which the composition was applied to a dry film thickness of 2 microns and baked at 100°C for 30 seconds) Steel plate (Comparative Example 7): Coated plates with the coating systems described in Examples 11 to 20 on the treated plates of Comparative Examples 1 to 7 (Comparative Example 1 → Comparative Example 8, Comparative Example 2 → Comparative Example 9, Comparative Example 3 → Comparative Example 10, Comparative Example 4 → Comparative Example 11, Comparative Example 5 → Comparative Example 12
, Comparative Example 6 → Comparative Example 13, Comparative Example 7 → Comparative Example 14); and coated boards of the coating systems described in Examples 21 to 30 on the treated boards of Comparative Examples 1 to 7 (Comparative Example 1 → Comparative Example 15, Comparative Example 2 → Comparative Example 16, Comparative Example 3 → Comparative Example 17, Comparative Example 4 - Comparative Example 1
8. Comparative Example 5 -> Comparative Example 19, Comparative Example 6 - Comparative Example 20, Comparative Example 7 -> Comparative Example 21) were prepared respectively, and these coated plates were subjected to a salt spray test, a wet test, and a paint film adhesion test. are shown in Table-2, Table-3 and Table-4 below.

Examples 31 to 40 Cold rolled steel plates (GIS, G-31
41.0.5 mm thickness) Examples 1 to 1 shown in Table 1 above
The composition No. 10 was applied to a dry film thickness of 5 microns and baked at 100° C. for 30 seconds. When this coated plate was subjected to a salt spray test, it showed excellent corrosion resistance as shown in Table 5.

gender was recognized.

Comparative Examples 22 to 28 Coated plates were prepared in the same manner as in Comparative Examples 1 to 7, except that the coated metal was replaced with a cold rolled steel plate, and a salt spray test was conducted. Table 5 shows the results.

Examples 41-50 In Examples 1-10, the coated metal was an aluminum plate (J
A coated plate was prepared in the same manner except that the plates were replaced with (IS, At Ps), and the corrosion resistance was tested by the CASS test method. As shown in Table 6, excellent corrosion resistance was observed.

Comparative Examples 29 to 35 In Comparative Examples 1 to 7, the coated metal was an aluminum plate (
JIS, AIPs) and others.

A coated plate was prepared in the same manner and a cast test was conducted. The results are shown in Table 6.

Table 2 Note: Based on JIS-Z-2371 salt spray test method.

Attention The progression of metal corrosion progresses through the formation of white rust and finally the formation of red rust.

Table-3 Note 9 Peeling width for flat section/cross cut section.

All results are based on cellophane tape peeling test.

-Table-4 Note ω JIS, -Z-2371, flat part/cross cut part peeling width mm.

Note 9: The coated plate was placed in a moisture resistance test box at 50°C and 100% RH for 2000 hours and then taken out.

The condition of the painted surface was observed.

Note 0: After making 11 orthogonal openings on the coating surface at lam intervals and reaching the base surface using a sharp knife, and processing to obtain 100 square openings, It was extruded and deformed from the back side to a depth of 5IIlf+ using an Erichsen extrusion tester. The center of the side part and the center of extrusion were made to coincide. Next, a cellophane adhesive tape with a width of 20 mm is pressed tightly by hand onto the surface of the coating on the side marks, and then it is rapidly peeled off to determine the number of lines remaining without being removed. displayed.

Table 5 Table 6 Notes: Based on J I 5-H-8601, CALMATA test method.

[Effects of the Invention] As is clear from the above description, according to the present invention, chromic acid is added to a silica-organic resin composite composition that exhibits performance equivalent to or better than conventional phosphate and cucomate surface treatment agents. By using these compounds together, a film is formed that exhibits excellent rust prevention properties for metals due to their mutual additive effects. This film not only exhibits rust prevention properties by itself, but also exhibits excellent coating base properties and can provide adhesion and corrosion resistance to top coats.

Moreover, it is a labor-saving surface treatment composition that can be applied without washing.

Claims (1)

[Scope of Claims] 1. An inorganic-organic composite reactant consisting of water-dispersible silica, a water-soluble or water-dispersible organic polymer resin, and a di- or tri-alkoxy (or alkoxyalkoxy) silane compound, Or a highly corrosion-resistant metal surface treatment composition characterized by mixing a water-dispersible chromium compound. 2. A patent claim characterized in that the water-soluble or water-dispersible chromium compound is chromic anhydride, chromate, dichromate, chromium chromate consisting of hexavalent chromium and trivalent chromium, or a salt thereof. A highly corrosion-resistant metal surface treatment composition according to item 1.