JPS63175078A - Composition for metal surface treatment - Google Patents

Abstract

PURPOSE:To provide the titled composition capable of imparting coated metallic objects with outstanding corrosion and scratch resistances and coating film adhesiveness, comprising a chromic chromate compound, granular silicon oxide compound, water-swellable laminar silicate compound and water-dispersible organic resin, etc. CONSTITUTION:The objective composition comprising (A) a chromic chromate compound containing hexavalent chromium and trivalent chromium [pref., the amount of hexavalent chromium accounting for 20-80wt.% on a CrO3 basis, of the total amount of chromium], (B) a granular silicon oxide compound (pref., with a size 0.01-5mu), (C) a water-swellable laminar silicate compound (e.g., montmorillonite), and (D) a water-dispersible or water-soluble organic resin (e.g., acrylic resin). The concentration of the component C is pref. 0.1-10wt.% or a solid content basis in the composition liquid.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a metal surface treatment composition, and more specifically, to a metal surface treatment composition that can impart excellent corrosion resistance, scratch resistance, and coating adhesion to a metal object coated with a coating. The present invention relates to a metal surface treatment composition that can be used.

[Prior Art and Problems to be Solved by the Invention] Painting is generally performed for the purpose of decorating metals and preventing corrosion. In this process, so-called surface treatments such as zinc phosphate, iron phosphate, chromate, and anodic oxidation treatments are performed in order to increase the affinity between the metal and the paint film and provide corrosion resistance and paint film adhesion. In recent years, in the field of metal painting, with the aim of saving labor in the painting process, reducing manufacturing costs, and making the painting process non-polluting for environmental protection, chemical conversion coatings have been formed through conventional chemical reactions with metals, and subsequent treatments have been carried out. A coating/waterless chromate treatment that eliminates cleaning work has been developed and is being implemented in the field of pre-coated plates (painted metal plates that have been coated with coils in advance). This coating type chromate treatment agent uses chromic chromate, which is a composite compound of trivalent chromium and hexavalent chromium, as the main ingredient, and various additives are also used to impart corrosion resistance, scratch resistance, and film-forming properties. Compositions are proposed. For example, those using silica particles as an additive in addition to the main ingredient (Japanese Patent Publication No. 42-14050, Japanese Patent Publication No. 45-38891);
Those using organic polymer resin (Special Publication No. 56-15790)
(Japanese Patent Publication No. 50-103437), those using silica and organic polymer resin (Japanese Patent Publication No. 56-39393), and those using organic polymer resin and heavy metal ions (# Publication No. 59)
14552), and one using an organic polymer resin and orthophosphoric acid (Japanese Patent Application Laid-open No. 123775/1982).

In general, pre-coated boards go through a process of being processed into intended objects at the customer's end. For example, home appliances such as refrigerators and washing machines, office furniture such as lockers and cabinets,
Forming processes such as roll forming, rock forming, pen forming, and press forming, as well as their handling operations, are used in a wide variety of fields such as roofing materials, building materials such as interior and exterior wall materials, and automobile parts such as doors, hoods, and fenders. It will be done. In this case, scratches and scratches may occur on the coated plate due to molds or tools used in the forming process, and the coating may peel off to expose the metal base. Such a condition not only impairs the appearance of the coated board, but also causes a significant drop in performance, resulting in loss of value as a product (hereinafter this phenomenon is referred to as "scratchability"). As a means to avoid such a phenomenon, measures such as applying a strong coating film, improving the adhesion between the coating film and the metal, and adjusting the surface morphology of the metal material or surface treatment film are generally taken.

In particular, the scratch resistance is correlated with the surface roughness of the metal or the surface treatment film, and in surface treatment, zinc phosphate films that form a film with a depth of 1 to several microns are generally good. However, it has been pointed out that the coating type chromate that has been put into practical use has a film thickness of 0.1 micron or less, and therefore has poor scratch resistance when the metal material is relatively smooth. As a measure to compensate for these shortcomings, the above-mentioned
A technique that uses silica, which is an inorganic particulate material with high hardness, as described in No. 5-38891, or a technique that uses a fine particulate organic resin as described in JP-A No. 58-213064. is proposed.

However, the specific gravity of this type of treatment agent that is generally put into practical use is around 1 to 1.2, and the dispersion stability of silica particles (2, 3) with large specific gravity is limited by the fact that the particle size is at most 0.
．． Particles with a particle size of 3 microns or less and larger are:
It quickly settles and separates in the treatment liquid, and tends to form aggregates that cannot be redispersed over time. Therefore, in methods of continuous application at high speeds such as roll coating,
Since the particle size of silica is limited, the target surface roughness may not be obtained and scratch resistance may not be sufficient. Similarly, it is known that a completely similar behavior is exhibited when a particulate organic resin is used.

On the other hand, the strength of the film formed by a surface treatment agent using relatively coarse silica powder, which is known to be the most effective for scratch resistance among the above methods, is extremely weak and cannot be rubbed with a finger. It is recognized that it easily powders or cracks and peels off. Even when a film in such a state is applied as a coating for treating a base for painting, the film adhesion when used as a coated plate is extremely poor and is unsuitable for practical performance. Furthermore, dust containing hexavalent chromium is generated from the surface treatment film due to mechanical action during roll coating, which becomes a source of pollution and poses many problems from the standpoint of environmental protection.

The purpose of the present invention is to solve the above-mentioned conventional problems and improve corrosion resistance.
The object of the present invention is to provide a stable surface treatment composition that forms a surface treatment film with excellent scratch resistance and film adhesion and is free from sedimentation and separation.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have conducted extensive research into the knowledge described above.

A water-swellable layered silicate is added to a composition consisting of a chromic chromate compound (hereinafter referred to as "chromate") consisting of hexavalent chromium and trivalent chromium and a particulate silicon oxide compound (hereinafter referred to as "silica"). A composition containing a compound (hereinafter referred to as "layered silicate") and a water-dispersible or water-soluble organic resin (hereinafter referred to as "organic resin") improves the scratch resistance and adhesion of the coating film. The present inventors have discovered that it is possible to form a film that greatly improves silica, and to form a stable water-dispersible composition in which sedimentation and separation of silica is suppressed, and the present invention has been completed.

That is, the present invention contains (A) a chromic chromate compound consisting of hexavalent chromium and trivalent chromium, (B) a particulate silicon oxide compound, (C) a water-swellable layered silicate compound, and (D) an organic resin. The present invention relates to a metal surface treatment composition characterized by:

The chromate compound of component (A) used in the present invention is a composite compound consisting of hexavalent chromium and trivalent chromium compound. The method for producing this chromate is not particularly limited, but it can be obtained, for example, by partially reducing a hexavalent chromium compound such as chromic anhydride, water-soluble chromate or dichromate. Examples of reducing agents include polysaccharides such as sucrose and starch; alcohols such as methanol, ethanol, isopropyl alcohol, cellosolve, and ethylene glycol; compounds such as hydroquinone, formaldehyde, and amines; Substances containing functional groups that perform oxidation-reduction reactions can be used. Hydrogen peroxide is preferred as an inorganic substance.To obtain a partially reduced chromate, a reducing agent is added according to stoichiometric calculations so that the ratio of hexavalent chromium to trivalent chromium is within a predetermined range, and the reaction is carried out. Preferably, heating is performed for the purpose of completing the reduction reaction.

The ratio of hexavalent chromium in the chromate in the present invention is in the range of 20 to 80% by weight (in terms of CrO3), preferably 40 to 70% by weight, based on the total chromium amount.

If the amount of hexavalent chromium is less than 20%, the corrosion resistance of the metal will not be sufficient, and trivalent chromium in the metal surface treatment composition will aggregate, resulting in poor liquid stability. Moreover, if it exceeds 80% by weight, the water-soluble hexavalent chromium compound in the metal surface treatment film is large, so the water resistance of the coated plate becomes insufficient and blisters are likely to occur.

In addition, the stability of the chromate solution is p) 11.5 to 3.5.
In the partial reduction reaction between a chromic acid compound and a reducing agent, a predetermined p
It is necessary to adjust it so that it is within the H range. That is, if the pH exceeds 3.5, trivalent chromium in the chromate aggregates and gels, making it unsuitable as a treatment solution. Further, when the pH is lower than 1.5, corrosion of the metal to be coated occurs, and the function as a surface treatment agent is lost. The pH
The modifier is not particularly limited as long as it is a compound or a concentration range that does not affect the desired performance even if it remains in the metal surface treatment film. Preferably, the acid component has a metal corrosion-preventing function. As the phosphoric acid and alkali components, potassium hydroxide, potassium carbonate, etc., which have an auxiliary function of forming a film, are selected.The chromate solution of the present invention can be produced only by the method of partial reduction using a chromate compound as a starting material as described above. Alternatively, the water-soluble trivalent chromium compound and the water-soluble chromic acid compound that already exist can be mixed and manufactured at a predetermined mixing ratio.

Component (B) silica in the present invention is a main component for forming a scratch-resistant film. Silica that can be used for this purpose is classified into the following two types depending on the form in which it is supplied to the market, and both can be used in the present invention.

(i) Silica powder: fine particulate silica synthesized by a gas phase method using a silicon tetrachloride compound as a starting material. So-called amorphous, porous synthetic 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 can be used. For example, Aerosil 200.0X50, which is indicated by the product name "Aerosil". TT600 (7) Pure silica, silica-alumina modified products such as MOX80, MOX170, C0K84, R972 hydrophobic silica, and Thyroid 244.26 indicated by the trade name “Thyroid”
Examples include 6.7265.978 or 162 with hydrophobic treatment.

(11) Water-dispersible silica: So-called colloidal silica, which is produced by desodiumization of water glass. This product is usually supplied as an aqueous dispersion. The effective form of colloidal silica that can be used in the present invention is an acidic dispersion system or a dispersion system of particles whose silica surface is modified with aluminum. For example, Snowtex 0. Examples include OL and C. The above are representative varieties and are not particularly limited, but have functions that contribute to the scratch resistance that is the objective of the present invention, and do not adversely affect the performance of corrosion resistance and paint base properties. Any inorganic fine particles can be used. Examples include aluminum silicate, magnesium silicate, calcium silicate, alumina, titania, zirconia, silicon nitride, and silicon carbide.

The particle size of silica that is effective in the present invention is in the range of 0.01 to 5 microns, preferably 0.1 to 1 micron.If the particle size is less than 0.01 micron, scratch resistance, coating adhesion, and corrosion resistance will deteriorate. Inability to fully demonstrate the functions of
If it exceeds microns, even if an inorganic thickener described later is used, sedimentation will occur and the stability of the metal surface treatment solution will deteriorate. In addition, the formed metal surface treatment film becomes brittle, resulting in poor coating and adhesion.

The amount of silica blended in the composition is in the range of 10/90 to 70/30, preferably 30/70 to 50,150 in weight ratio of silica/chromate. Silica amount is 10%
If the amount of chromate is less than 90% or more than 90%, scratch resistance, coating adhesion, and corrosion resistance will deteriorate. Moreover, if it exceeds 70%, the formed film becomes brittle and the adhesion of the coating film decreases.

The water-swellable layered silicate as component (C) in the present invention is the most characteristic material of the present invention, which functions to prevent precipitation of the silica component of the composition. Moreover, since this material itself is hard fine particles, it can contribute to scratch resistance.

This layered silicate forms a stable colloid in a polar solvent such as water, alcohol, or amine, and changes from a sol state to a gel state depending on its concentration, and its dispersion exhibits chickentropic properties.

Therefore, by using an appropriate amount of water-swellable layered silicate, it is possible to uniformly disperse the inorganic particulate material having a large specific gravity and prevent sedimentation separation. In addition, due to its chicken-tropic properties, the viscosity becomes low due to shear surface stress during roll coating, making it possible to form a uniform film of a predetermined amount.

Water-swellable layered silicates with such functions are
A group of so-called montmorillonite minerals with 2-octahedral and 3-octahedral structures belonging to phyllosilicates, in which cationic ions with small ionic radius and high hydration properties such as Li, Na, and Ca are coordinated between the layers. Preferably. Such substances include, for example, montmorillonite [(OH)4S13(A, R3, 34°MgO, Ei
8) 020°NaO, 86] beidellite [(OH)a (S le, 34・” 1.6 fl)
"4.34020" NaO,68] Nontronite [(OH)4(S i7.34°Ano, ss) F
ei"o2o°Na0.68] Hectorite [(OH)4S 1 s(Mg5.3a°"' O,
8B) 020°Na0.68]Saponite[(OH)4(Si7.34bow”0.68)Mg1
3020" NaO, 138], etc. Also, as synthetic minerals having these forms, there are those synthesized by hydrothermal reactions or melting reactions depending on the composition of desired minerals. For example, -8
No. 13, hectorite-like structure compound described in JP-A-48-96499, saponite-like structure described in JP-A-58-181718 (S l 7.20A fLo, H)
(M g 5.97A Q o, o3) Fist-〇・77
・0.770 (OH)]
(NaMg) )20
4 0.49 0.14 Compounds, fluorotetrasilicon micas described in JP-A-52-150344 as a mica mineral group, for example, [N a M g2.5 (S f 4010) F27
, [Cao, 5 Mg2.5 (S ia 010) F
2].

[HMg2. s(S l a Ot.)F2], [
A sentence. , 3Mg2.5 (S1401°) F21, [B
a o, 5 Mg2.5 (S i 40 to) F2
].

Taeniolites, for example, [NaMgLi (S i40□, )) F2
], [LiMgLi(Si40□.)F2].

Fluorine hectorites, such as [N a HMg2(N) L i57. (S 1
a 0to) F2].

[L-g2 (%) Li tail (Si4°, 0) F2]・
etc. are valid.

Examples of specific products include Osmos, a product made from refined natural bentonite belonging to the montmorillonite family;
Synthetic minerals include ``Smectone'', a trade name belonging to the savonite group, and ``Dimonite'', a trade name belonging to the fluorotetrasilicon mica group. In addition, organically modified layered silicates in which an amine compound or the like is inserted into the above-mentioned swelling type layered silicates, or layered silicates (natural or synthetic) that have water-swellability in addition to the above-mentioned substances have the functions required for the present invention. Any of these can be applied to the present invention and is not limited in any way.

The effective amount of the layered silicate used in the present invention is 0.1 to 10% by weight as solid content in the liquid composition. If the concentration is less than 0.1% by weight, a liquid viscosity effect sufficient to prevent the sedimentation of silica particles cannot be obtained, and if it exceeds 10% by weight, the composition liquid will completely gel and take on a hard cake-like appearance. Even when subjected to immediate stress, it no longer exhibits fluidity and cannot be used as a surface treatment agent.

The water-dispersible or water-soluble organic resin of component (D) in the present invention is used as a binder to form a strong film in the surface treatment composition of the present invention. When the organic resin used for this purpose is added to the mixture of components (A), (B), and (C) in the above-mentioned composition, it does not gel and can be stably dispersed, and component (A) The type of organic resin is not particularly limited as long as it does not undergo a redox reaction with the chromic acid compound in a short period of time. Examples of such organic resins include acrylic resins, alkyd resins, epoxy resins, and polycarbonate resins. Acid resin, polyamine resin, amino resin, amide resin, polystyrene resin, polyolefin resin, fatty acid or polybasic acid-modified polybutadiene resin, methylol group-introduced phenol resin, alkanolamine-modified polyurethane resin, acrylic acid-added polyethylene resin, polyvinyl alcohol, polyvinylpyrrolidone , polyvinyl methyl ether, etc.

Among these resins, acrylic resins have particularly good stability in the composition of the invention.

Acrylic resins for such purposes include water-soluble or water-dispersible acrylic resins synthesized by solution polymerization, emulsion polymerization, or suspension polymerization using ordinary unperturbed ethylenic monomers, and alkyds. Acrylic resin modified with resins such as epoxy, butadiene, urethane, phenol, and amide.

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

Furthermore, 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-modified epoxy resin, and amine-modified epoxy resin. Examples include urethane-modified epoxy resins.

These resins are anionic in charge.

It can be used regardless of whether it is cationic, zwitterionic, or nonionic.
In addition, it can be used in any form such as an aqueous solution, an emulsion, or a fine powder.

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

The blending amount of the organic resin in the composition is 2 to 20% by weight, preferably 5 to 15% by weight, based on the total amount of components (A), (B), and (C) of the composition. . If the blending amount is less than 2% by weight, the effect as a binder will not be obtained and the formed film will be easily powdered. Moreover, if it exceeds 20% by weight, the organic resin will completely cover the silica particles that have the desired effect of improving scratch resistance, so that a film that is expected to have good scratch resistance will no longer be formed. Furthermore, since the extreme surface layer of the formed film is covered with the organic resin, selectivity is expressed in terms of adhesion with the top coat, and the effect as a wide-range paint base treatment film is lost.

The method for producing the composition of the present invention first includes the above-mentioned component (A).
After a predetermined amount of chromate and CB) silica are blended and both are thoroughly dispersed and mixed under stirring, layered silicate (C) is further added under stirring to cause swelling.

CD) The water-dispersed or water-solubilized organic resin is then carefully and gradually added while stirring. Subsequently, the composition is determined to have an appropriate P.
I (It can be carried out by adjusting the above acid or alkali so that it falls within the range.

The metal surface treatment composition of the present invention can be applied to iron or iron alloys, aluminum or aluminum alloys, zinc or zinc alloys, copper or copper alloys, tin or tin alloys, or metals made of multiple layers of these metals. In addition, these metals are further treated with phosphate, chromate,
So-called surface-treated metals that have been subjected to cobalt-iron composite oxide film treatment or electrolytic treatment are subjected to a predetermined degreasing treatment to clean the metal surface, and then applied with roll coating, spray coating, dipping coating, dipping coating, etc. It can be coated by the method described above and then dried to form a metal surface treatment film.

The above dry film amount is 10 to L00 in terms of chromium atoms.
0mg/rn', preferably 30-300mg/rn'
The amount falls within the range of . Is the film amount 10 tag/rr? If it is less than that, the film will be so thin that it will not be possible to obtain the surface shape necessary for scratch resistance, and the corrosion resistance will also be significantly inferior. Furthermore, if the coating amount exceeds 1000 mg/rrf, the formed coating becomes brittle and the adhesion of the coating decreases. The drying conditions may be as long as the moisture in the chromate composition evaporates, but the temperature is usually in the range of 60 to 250°C, preferably 100 to 200°C. If the film formation temperature is less than 60° C., the watertightness may deteriorate even if the film formation temperature is lower than 60° C. In addition, the film formation temperature is 2
If the temperature exceeds 50°C, not only will hexavalent chromium be reduced during film formation, but also water-soluble hexavalent chromium in the film will be significantly reduced, resulting in insufficient corrosion resistance of the coated product.

The surface-treated metals thus obtained can be coated for the purpose of imparting decorative properties, anticorrosion properties, and functionality.

In other words, any conventionally known organic solvent-based, water-based, solvent-free, or powder-based paint can be applied, and depending on the purpose of coating, a single layer film or a multilayer film such as two or three layers can be applied. It is possible to do so. These coatings can be applied using any coating method such as roll, spray, dipping, brushing, electrophoresis or electrostatic coating, and baking can be done by room temperature curing, heat curing, infrared curing, or ultraviolet curing, depending on the type of topcoat. Any method such as curing or electron beam curing is possible. For example, electrodeposition-intermediate coating and top-coating systems for automobiles, etc.; brimer-top coating systems for pre-coated metals for building materials; one-coat systems for 4 steel electrical appliances; heavy-duty anti-corrosion coatings for ships, bridges, pipes, etc. Systems and resin linings other than painting, laminate systems, etc. are possible.

Metal ions, such as cobalt, nickel, titanium, and zirconium, which are known to have a surface conditioning function on metals, can also be added to the metal surface treatment composition of the present invention. Furthermore, a so-called silane coupling agent or titanium coupling agent, which is known as a bonding agent between an organic compound and an inorganic compound, can also be added as a film-forming reinforcing material.

[Examples] Examples and comparative examples are shown below. These examples explain the present invention in more detail, and do not limit the scope of the present invention. 0 parts and % are parts by weight. %
shows.

Example 1 150 parts of chromic anhydride (CrO3) was dissolved in 1000 parts of water, 13 parts of corn starch was added thereto, and the mixture was heated and boiled for 3 hours to obtain a partially reduced chromate compound with a solid content of 16%. The amount of hexavalent chromium in this chromate compound is
The amount was 63.2% by weight in terms of CrO3 based on the total amount of chromium.

Next, silica powder (manufactured by Nippon Aerosil Co., Ltd., trade name "Aerosil Ox↓ 50") and water-swellable layered silicate powder (manufactured by Kunimine Kogyo Co., Ltd., trade name "Sumecton") were added to the water-dispersible chromate solution at a solid content of 12. %, 12%, and 1%, and then polyacrylic acid resin (manufactured by Wako Tsumugi Pharmaceutical Co., Ltd., trade name "Polyacrylic Acid") was added at a solid content of 1.3% under stirring. 5
By mixing for several minutes, the viscosity (Brookfield rotational viscometer 6760 rpm value 165 / 88
We prepared a metal surface treatment agent with high 70% cell size.

Immediately after manufacturing the above surface treatment agent, 450. Pour 200g into a J mayonnaise bottle, and check the appearance after leaving it at room temperature for 24 hours.
After stirring 40 times/min for 10 minutes, the appearance was observed and stability was investigated. As a result, no abnormality was found and no precipitate was observed.

Next, a minimum spangle hot-dip galvanized steel sheet that had been degreased with a silicate-based alkaline cleaner (manufactured by Nippon C-O Biichiban Chemical Co., Ltd., product name "CC561BJ") was coated with the surface treatment agent of Formulation Example 1 above in a dry film amount of chromium. Conversion 50
mg/m" and then dried under conditions that reached a peak metal temperature of 100°C to create a yellow-brown chromate surface-treated board. Next, this treated board was coated with epoxy primer paint for pre-coated metal ( Manufactured by Kansai Paint ■, product name: rKP Color 8470 Brimer'')
was coated and cured by heating at 210° C. for 50 seconds to create a coated plate with a film thickness of 5 microns. Next, a polyester topcoat (manufactured by Kansai Paint ■, trade name: rKP Color 1470 Blue) was applied to this coated plate and baked at 220°C for 50 seconds to create a coated plate with a total dry film thickness of 25 microns.About this coated plate Scratch resistance (coin scratch test, load retest), seam adhesion, salt spray corrosion resistance,
As shown in Table 2, the results of testing for moisture resistance were as follows:
All results were good.

Examples 2 to 10 Metal surface treating agents were prepared in the same manner as in Example 1 with the formulations shown in Table 1, and their stability was tested as shown in Table 2. A coated plate was prepared and a performance test was conducted in exactly the same manner as in Example 1. Table the results.
Shown in 2. All showed excellent performance.

Examples 11 to 21 In Example 1, the metal to be coated was a steel plate, a stainless steel plate,
Aluminum plate, chromium-magnesium/aluminum alloy plate, 5% aluminum/galvanized steel plate, 55% aluminum/galvanized steel plate, copper plate, tin-plated steel plate, zinc phosphate treated hot-dip galvanized steel plate, chromic acid electrolytic treated steel plate, cobalt- A coated plate was prepared and a performance test was conducted in exactly the same manner as in Example 1, except that a galvanized steel plate treated with an iron composite oxide film was used. The results are shown in Table-3. All showed excellent performance.

Comparative Examples 1 to 10 Metal surface treatment agents were prepared with the formulations shown in Table 1. The stability of the treatment agents is shown in Table 2.Next, these treatment agents were used to prepare coated plates and perform performance tests in exactly the same manner as in Example 1. These results are shown in Table-2.

Comparative Examples 11-21 Using Comparative Example 7, coated plates were prepared and performance tests were conducted in the same manner as in Examples 11-21. Table these results.
Shown in 3. All of these had poor coating film adhesion.

Ai 14 scratch - 4 = Hold a 10 yen copper coin without notches in your hand at 45 degrees to the painted surface and scratch the painted surface hard enough to reach the substrate.The length of the scratch is about 50 m + 50 m, and the scratches form a cross at right angles. Check the appearance of the painted surface.

Evaluation score: 5: Only scratches on the painted surface, no exposure of the base material at all.

tt 3: Exposure of the base material is observed in some areas such as the intersection of the crosses.

//　　　1　: The base material is clearly exposed.

Sadness 15, −+ −’−.

Two 50 x 50 mm square coated plates (A and B) are put together, and a load of 10 kg/cts2 is applied, and the B coated plate is rotated 90 degrees with respect to the A coated plate. After that, check the appearance of the painted surface.

Evaluation score: 5: Only scratches on the painted surface, no exposure of the base material at all.

tt 3: Slight exposure of the base material is observed.

Evaluation score 1: Exposure of the substrate with a length of 10+am or more is observed.

Wood 16-edge I: Bend about 1,800 degrees around a rod with a diameter of 2 mm with the painted surface of 50 mm wide removed, insert a plate of the same thickness as the test piece around this part, and tighten it using a vise.

Next, press the cellophane adhesive tape firmly with your hand to make it stick, then quickly peel it off and observe the degree of peeling. The number of boards to be inserted between the bends is indicated as shown below.

OT: When no plates are sandwiched IT: When one plate is sandwiched 2T: When two plates are sandwiched Evaluation points 5: No peeling of the coating film at all 1/4: Total length of peeling is 3±1■/ / 3
: tt f3±2mm //
2: tt l 7±3mm tt
1: tt 3 Q±4mm u
LJ mouth 1 series collapse" - Diameter 12.7m using DuPont type drop impact tester
+a Kennin set on a painted board, 1kg from 50cm in height
drop the weight. Next, firmly press the cellophane adhesive tape onto the affected area by hand to make it adhere, then rapidly peel it off and observe the degree of peeling.

Evaluation points 5: No defects at all 4: Slight cracks in the paint film 1/3: Cracks but no peeling 1/2: Cracks and partial peeling Case in which peeling has occurred tt 1 : Case in which the entire crack part has peeled off No. 18: According to J I 5-Z-2371. A cross cut is made on the painted surface with a knife to reach the substrate, and after a certain period of time, the peeling width of the single-sided paint film from that area is evaluated.

According to 51 "1 Moisture" Obtained 2 J I 5-Z-0228. Painted plate 50'0.1
After being placed in a humidity test box at 00% RH for 2000 hours, the sample was taken out and the condition of the coated surface was observed.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, coarse silica powder can be uniformly dispersed in a chromate treatment agent without sedimentation and separation. It is possible to form a metal surface treatment film that exhibits uniform surface properties.

Furthermore, by using an organic resin as a bonding material, it is possible to compensate for the film strength, which is a drawback when coarse-grained silica is used. Therefore, with this method, it is possible to prevent scratches and ironing scratches on the painted board, which were difficult points in the conventional paint-on chromate treatment for brenny metal painting, and to achieve excellent paint film adhesion and corrosion resistance. It is a composition that provides.

Claims (1)

[Claims] 1. (A) Chromic chromate compound consisting of hexavalent chromium and trivalent chromium (B) Particulate silicon oxide compound (C)
A metal surface treatment composition comprising a water-swellable layered silicate compound and (D) a water-dispersible or water-soluble organic resin. 2. The amount of hexavalent chromium in the chromic chromate compound (A) is 20 to 80% by weight (CrO_
3). The metal surface treatment composition according to claim 1. 3. The weight ratio of chromic chromate compound (A)/particulate silicon oxide compound (B) is 90/10
30/70. The metal surface treatment composition according to claim 1. 4. The particle size of the particulate silicon oxide compound (B) is 0.01
5. The metal surface treatment composition of claim 1, wherein the metal surface treatment composition has a particle diameter of 5 microns. 5. The metal surface treatment composition according to claim 1, wherein the concentration of the water-swellable layered silicate compound (C) is 0.1 to 10% by weight as solid content in the composition liquid. 6. The concentration of the water-dispersible or water-soluble organic resin (D) is 2 to 20% by weight based on the total amount of components (A), (B), and (C) according to claim 1. Metal surface treatment composition.