JPH04202781A - Aluminum alloy sheet excellent in scratch resistance and corrosion resistance and its production - Google Patents

Abstract

PURPOSE:To produce a surface treated Al alloy sheet excellent in scratch resistance, corrosion resistance, adhesive strength of coating, external appearance characteristics of coating finish, etc., by applying chromate treatment to the surface of an Al alloy sheet, applying an organic resin composition to the above surface, and then exerting baking treatment. CONSTITUTION:Chromate treatment is applied to an Al alloy sheet. It is preferable to perform this treatment by applying a chromating solution of prescribed composition and exerting drying without water washing. Further, it is preferable to regulate the chromate coating weight of the resulting chromating layer to 10-200mg/m<2> expressed in terms of Cr. Subsequently, an organic resin composition is applied and baked. This organic resin composition is constituted by blending prescribed amounts of silica, chromate of limited solubility, etc., with epoxy resin or its derivative and further adding, if necessary, a curing agent. By the above procedure, an organic resin film is formed as a second layer on the above chromating layer, and it is preferable to regulate the thickness of this film to 0.3-5mum. By this method, the Al alloy sheet suitable for material, e.g. for automobile body use and excellent in scratch resistance, corrosion resistance, etc., can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aluminum alloy plate with excellent scratch resistance and corrosion resistance used in automobile bodies, home appliances, etc., and a method for manufacturing the same.

[Conventional technology]

Conventionally, steel plates have been widely used for automobile bodies, but in recent years, there has been a strong demand for significant weight reduction of automobile bodies with the aim of improving automobile fuel efficiency. Based on this background, aluminum alloy plates are being actively developed as a material for automobile bodies to replace steel plates, and are already being used in some automobiles.

On the other hand, even when aluminum alloy sheets are applied to automobile bodies, they require the same quality characteristics after painting as steel sheets (e.g., external rust resistance, paint finish appearance, paint adhesion).
If the aluminum alloy plate is used as is,
Sufficient quality characteristics after painting (for example, external rust resistance, paint adhesion) cannot be obtained.

In addition, aluminum alloy plates have lower hardness than steel plates, and this poses a major problem in that they get scratched during handling and deteriorate the finished appearance after painting9.Conventionally, the external rust resistance of aluminum alloy plates has been improved. (1) A method of phosphate treatment of aluminum alloy plates in the manufacturing process of automobiles (U.S. Pat. No. 3,619,300)
(2) Method of chromate treatment of aluminum/nium alloy plates in the automobile manufacturing process (British Patent No. 1409)
No. 413) etc. have been proposed.

[Problem to be solved by the invention]

However, at present, steel plates and aluminum alloy plates are often used together in automobile bodies, and when steel plates and aluminum alloy plates are treated with phosphate at the same time, AI'''' ions eluted from the aluminum alloy plate form a phosphate film. There is a problem in that it inhibits formation. U.S. Patent No. 3619
According to the method shown in No. 300, if the phosphate treatment solution is selected according to the usage ratio of steel plate and aluminum alloy plate, it is possible to form a uniform phosphate film on any material. However, there is a problem in that the management of the processing liquid is extremely complicated.

Furthermore, the method shown in the above-mentioned British Patent No. 14094]3 is premised on treatment in the automobile manufacturing process, and in general, chromate treatment is used in the existing automobile manufacturing process based on steel sheet materials. Since there is no process, in order to implement the above method, a new chromate treatment process for aluminum alloy plates must be installed in addition to the existing phosphate treatment process.

Additionally, when aluminum alloy plates are chromate-treated in advance and assembled in the automobile assembly process, the chromate film tends to peel off during press forming and handling.
There is also the problem that performance deteriorates.

Furthermore, as mentioned above, aluminum alloy plates have low hardness, and there is a major problem in that they get scratched during handling, which deteriorates the finished appearance after painting, but chromate treatment alone could not improve the scratch resistance. .

In view of the above-mentioned problems, this invention provides a surface-treated aluminum alloy that has excellent scratch resistance and is also excellent in corrosion resistance, paint adhesion, and paint finish appearance as a material for automobile bodies, etc. It is intended to be made of wood.

[Means to solve the problem]

In order to achieve such an object, an aluminum alloy plate of the present invention has the following configuration.

(1) An aluminum alloy plate having excellent scratch resistance and corrosion resistance, which has a chromate layer as a first layer on the surface of the aluminum alloy plate, and an organic resin film as a second layer on top of the chromate layer.

(2) In (1) above, the amount of chromate deposited in the chromate layer is 10 to 200 mg/m in terms of metallic chromium.
An aluminum alloy plate having excellent scratch resistance and corrosion resistance, which is No. 2 and has an organic resin film thickness of 0.3 to 5 μm.

(3) The aluminum alloy plate according to (1) or (2) above, wherein the organic resin film contains silica in the following ratio (weight ratio) to the organic resin and has excellent scratch resistance and corrosion resistance.

Organic resin/silica = 90/10 to 40/60 (4)
The aluminum alloy plate according to (]) or (2) above, wherein the organic resin film contains a sparingly soluble chromate in the following ratio (weight ratio) to the organic resin and has excellent scratch resistance and corrosion resistance.

Organic resin/I-soluble chromate = 90/10 to 40/60 (5) In (1) or (2) above, the organic resin film is sparingly soluble with silica in the following ratio (weight ratio) to the organic resin. An aluminum alloy plate with excellent scratch and corrosion resistance that contains chromate.

Organic resin/(silica + poorly soluble chromate) = 90/
10-40/60 Silica/slightly soluble chromate: 90/10-10/90 (6) Above (1), (2), (3), (4) or (5)
), an aluminum alloy plate with excellent scratch resistance and corrosion resistance, in which the organic resin constituting the organic resin film is an epoxy resin.

(7) In (6) above, the epoxy resin is an epoxy resin having at least one basic nitrogen atom and at least two primary hydroxyl groups added to the terminal end of the resin. Superior aluminum alloy plate.

(8) Above (1), (2), (3), (4) or (5)
), the organic resin constituting the organic resin film is an epoxy resin with at least one basic nitrogen atom and at least two primary hydroxyl groups added to the end of the resin, a polyisocyanate compound, and a blocked isocyanate. An aluminum alloy plate with excellent scratch resistance and corrosion resistance, which contains at least one hardening agent selected from the group consisting of compounds in the following ratio (weight ratio).

Epoxy resin/curing agent = 9515 to 60/40 Further, the manufacturing method of the present invention for obtaining such an aluminum alloy plate has the following configuration.

(1) A method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance, which comprises subjecting the surface of the aluminum alloy plate to chromate treatment, and after drying, applying an organic resin composition and baking treatment.

(i) In (i) above, the surface of the aluminum alloy plate is subjected to a chromate treatment in which a chromate solution is applied and dried without washing with water, and then an organic resin composition is applied and a baking treatment is performed. A method for producing an aluminum alloy plate with excellent adhesion and corrosion resistance.

(ii) A method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance, characterized in that in (i) above, a chromate solution having a liquid composition adjusted as shown below is applied.

Chromic anhydride: 5-100g/l Phosphate ion = 0.5-20g/l Zirconium fluoride ion 20.2-4g/l Zinc ion 20.2-7g/I Cr"/Cr": 3/ 4 to 3/2 (weight ratio) chromium 1m/zirconium fluoride ion: 10/] to 100
/1 (weight ratio) (In (1), l) or (i) above, apply an organic resin composition containing silica in the following ratio (weight ratio of non-volatile content) to organic resin. A method for manufacturing aluminum alloy plates with excellent scratch resistance and corrosion resistance.

Organic resin/silica = 90/10 to 40/60 (v)
In (1), (E) or (i) above, an organic resin composition containing a sparingly soluble chromate in the following ratio (weight ratio of non-volatile content) to the organic resin is applied. A method for manufacturing an aluminum alloy plate with excellent scratch resistance and corrosion resistance.

Organic resin/slightly soluble chromate = 90/10 to 40/60 (v',) In (i) and (D or U) above, silica and silica in the following ratio (weight ratio of non-volatile content) to the organic resin. A method for producing an aluminum alloy plate having excellent scratch resistance and corrosion resistance, the method comprising applying an organic resin composition containing 1 lll soluble chromate.

Organic resin/(silica + poorly soluble chromate) = 90/10
~40/60 Silica/Release Chromate = 90/10~10/90 (i) Above (i), (i), (i), (il), (ma)
Or (vl), the method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance, wherein the organic resin constituting the organic resin composition is an epoxy resin.

(-) In the above (phantom), the epoxy resin has at least one basic nitrogen atom and at least two basic nitrogen atoms at the end of the resin.
A method for producing an aluminum alloy plate having excellent scratch resistance and corrosion resistance, which is made of an epoxy resin to which at least one primary hydroxyl group has been added.

(-) In the above (i), I), (i), (泗), (, ) or (η), the organic resin has at least one basic nitrogen atom and at least two or more basic nitrogen atoms at the end of the resin. No. 1
A scratch-resistant and corrosion-resistant product containing an epoxy resin added with class hydroxyl groups and at least one curing agent selected from the group consisting of polyisocyanate compounds and blocked isocyanate compounds in the following proportions (weight ratio of non-volatile components). A method for manufacturing aluminum alloy plates with excellent performance.

Epoxy resin/curing agent = 9515 to 60/40 [Function] The base aluminum alloy plate is an aluminum alloy plate containing one or more alloying elements such as copper, manganese, silicon, magnesium, zinc, chromium, and nickel. , this includes, for example, 2002.2117.2036.2037
．． 2038.3004.5052.5182.6009
．． There are aluminum alloy plates such as 6010.6015.6016.6111 materials.

The chromate layer formed on the surface of the aluminum alloy plate described above is caused by the passivation effect of chromate ions of CF6 + contained in the chromate layer and the chromium hydrated oxidation of Cr3'', which is a reduction product of chromate ions. Corrosion of the aluminum alloy plate is suppressed by coating the surface with an effect of reducing the anode area and the effect of the chromium hydrated oxide film of Cr3'' acting as a diffusion barrier for water and oxygen.

The amount of this chromate film attached is 10% in terms of metallic chromium.
■If it is less than /bo, sufficient corrosion resistance cannot be expected.
On the other hand, if the amount of adhesion exceeds 200 cm/bo, weldability deteriorates.

As the chromate treatment method for forming this chromate film, any method such as reaction type, electrolytic type, coating type, etc. can be applied.

In electrolytic chromate treatment, a treatment solution containing chromic anhydride to which sulfuric acid, phosphoric acid, halogen ions, etc. are added, or a treatment solution containing powder or colloids such as silica or alumina, or caotine such as cobalt or magnesium is used. using the added processing solution.

The aluminum alloy plate is subjected to cathodic electrolysis treatment using this treatment solution, then washed with water and dried to form a film. Usually, cathodic electrolysis treatment is performed, but it is also possible to add anodic electrolysis or alternating current electrolysis.

The main component of coating-type chromate treatment is a partially reduced chromic acid aqueous solution, which is usually supplemented with ■ water-soluble or water-dispersible organic resins such as acrylic resins and polyester resins ■ silica, alumina, titania, zirconia, etc. Oxygen acids and/or their salts such as molybdic acid, tungstic acid, and vanadate ■ Phosphoric acids such as phosphoric acid and polyphosphoric acid ■ Feces such as zirconium fluoride, silicon fluoride, titanium fluoride, etc. Compound ■ A treatment liquid containing one or more metal ions such as zinc ions added as necessary is applied to the object to be treated and dried without washing with water to obtain a film.

In the coating-type chromate treatment of the present invention, the treatment liquid is usually applied by a roll coater method, but it is also possible to adjust the coating amount by an air knife method or a roll squeezing method after applying by a dipping method or a spray method. .

In order to obtain a chromate film with better corrosion resistance, it is preferable to adjust the coating type chromate solution to the following composition.

Chromic anhydride = 5-100g/l Phosphate ion = 0.5-20g/l Zirconium fluoride ion = 0.2-4g/l Zinc ion: 0.2-7g/I Cr"/Cr": 3/ 4-3/2 (weight ratio) chromic acid/zirconium fluoride ion: 10/1 to 100/
1 (weight ratio) Here, if the concentration of chromic anhydride is less than 5 g/l, a chromate film cannot be sufficiently formed on the surface of the object to be treated, resulting in poor corrosion resistance. On the other hand, the concentration of chromic anhydride is 1
If it exceeds 00 g/l, the amount of chromate film deposited becomes too large and weldability deteriorates.

Phosphate ions have the effect of preventing the gelation of (r3+) and the effect of reacting with zinc ions to form poorly soluble salts and improve corrosion resistance, but if the amount is less than 0.5 g/l, the application specified by the present invention will not be possible. Cr' in type chromate treatment solution
/Cr3'' ratio, the effect of preventing gelation becomes insufficient and tends to cause precipitation in the treatment solution.On the other hand, 2
If it exceeds 0 g/l, the pH of the treatment liquid will be excessively lowered,
Accelerates melting of the aluminum alloy plate to be treated and deteriorates corrosion resistance.

Among fluorides, especially zirconium fluoride ion,
It has the effect of suppressing the excessive elution of Cr''' ions, which form a complex with Or'''' chromate ions and contribute most to corrosion resistance, from the chromate film, but if the concentration is 0.
If it is less than 2 g/l, the effect of suppressing the elution of Cr''' ions is insufficient, the Cr''' ions are quickly consumed, and the corrosion resistance is slightly deteriorated. On the other hand, if the concentration exceeds 4 g/l,
Excessive etching of the surface of the aluminum alloy plate to be treated deteriorates corrosion resistance.

Among metal ions, the chromate ion of Cr''+ in the chromate film is converted into zinc chromate to prevent the elution of Cr- ions during the degreasing process, which is a pre-treatment process for car painting. However, if the concentration is less than 0.2 g/l, the effect of suppressing the elution of CrG + ions is insufficient, and chromium ions are removed when waste degreasing solution is released into the environment. Waste liquid treatment is required. On the other hand, if the concentration exceeds 7 g/l, the chromate treatment liquid tends to gel, which poses a problem.

The weight ratio of CrG4/C,3L'' in the treatment solution is 3/
If it is less than 4, the chromate treatment solution tends to gel, and chromic acid in Cr''' in the chromate film becomes insufficient, resulting in deterioration of corrosion resistance.On the other hand, CrG*/C
When the weight ratio of r 3 * exceeds 3/2, the water resistance of the chromate film deteriorates and paint adhesion deteriorates.

If the weight ratio of chromic acid/zirconium fluoride ions in the treatment solution is less than 10/1, the complex formation reaction of CrG4 with chromate ions by zirconium fluoride ions will proceed excessively, causing chromic acid of Cr It inhibits the self-healing effect of ions and deteriorates corrosion resistance. On the other hand, 100
If it exceeds /1, the complex formation reaction will be insufficient, and the corrosion resistance will also deteriorate.

Comparing the chromate films obtained by coating type chromate treatment and electrolytic chromate treatment, the coating type has superior corrosion resistance because it contains more Cr- chromate ions in the coating. On the other hand, the electrolytic type has the advantage that the amount of chromium eluted in a pre-painting treatment process such as an automobile degreasing process is small, and the amount of film deposited can be easily adjusted.

When considering corrosion resistance, coating type chromate treatment is most preferable.

The organic resin film formed as a second layer on top of the chromate film formed on the surface of the aluminum alloy plate suppresses excessive elution of chromate ions of Cr''' in the chromate layer into the corrosive environment. In addition to sustaining the anticorrosion effect, the silica and chromate added to the organic resin film further improve corrosion resistance.

In the organic resin coating treatment in the present invention, the resin composition is usually applied by a roll coater method and then heat treated. Afterwards, it is also possible to perform heat treatment.

If the amount of organic resin film deposited is less than 0.3 μm, sufficient scratch resistance and corrosion resistance cannot be expected;
If it exceeds 5 μm, weldability and electrodeposition coating properties deteriorate. Moreover, in order to satisfy even higher scratch resistance, corrosion resistance, weldability, and electrolytic coating property, the range of 0.4 to 2 μm is preferable.

The heat treatment is performed at a final plate temperature of 50 to 300°C, preferably 6
It is carried out in the range of 0 to 250°C. Further, as a heating method, a hot air stove, a high frequency induction heating furnace, an infrared furnace, etc. can be used.

The organic resin film may be made of any of solvent-based resins, water-soluble resins, and water-dispersed resins. For example, epoxy resins, acrylic resins, polyester resins, amino resins, polyurethane resins, and fluorine resins. It is possible to use resins such as silicone resins, silicone resins, phenolic resins, and copolymers thereof.

From the viewpoint of corrosion resistance, solvent-type resins that are less likely to draw water into the film in a corrosive environment are preferred, and solvent-type epoxy resins are particularly excellent in corrosion resistance and paint adhesion.

As the above-mentioned epoxy resin, an epoxy resin which is a condensation product obtained by condensing bisphenol A and epichlorohydrin is excellent in terms of corrosion resistance, paint adhesion, etc. Examples of this epoxy resin include Epicoat 828.1001.1004.100 manufactured by Yuka Shell Epoxy Co., Ltd.
7.1009.1010 etc. can be used alone or in combination.

In addition, basic epoxy resins with at least one basic nitrogen atom added to their terminals have a resin structure that does not deteriorate due to alkali generated at the interface during cationic electrodeposition coating, which is especially applied to automobiles. Good adhesion can be obtained. Furthermore, by introducing 2 moles or more of primary hydroxyl groups into one molecule of the epoxy resin, the resin structure can be made more dense.

In order to introduce a basic nitrogen atom and a primary hydroxyl group into an epoxy resin, for example, there is a method of adding an alkanolamine and/or an alkylalkanolamine to the epoxy group of the epoxy resin. Examples of these amines include monoethanolamine, jetanolamine, dimethylaminoethanol, monopropanolamine, dibrobanolamine, jetanolamine, etc., and these amines can be used alone or in combination. .

Furthermore, if an average of 2 moles or more of primary hydroxyl groups can be introduced into one molecule of the epoxy resin, the epoxy resin can be partially modified with another compound. Methods for partial modification include (1) esterification with monocarboxylic acids, (2) modification with aliphatic or aromatic amines, and (3) modification with oxyacids. There is also a modification method using dicarboxylic acid, but this method is not suitable for the resin composition of the present invention because it makes it difficult to control the molecular weight.

The above-mentioned epoxy resin can also be used as a water-dispersed or water-soluble resin by neutralizing its base portion with a low-molecular acid. However, when used in this way, it is not possible to obtain a strong film when heat-treated at low temperatures, and the acidic compounds used for water solubilization form salts in the film, causing water to evaporate in a humid environment. Because it is easy to attract into the film,
Corrosion resistance and paint adhesion will deteriorate. Furthermore, when used as a water-dispersed or water-soluble resin, there is a problem that chromate ions of CrGO in the lower layer chromate film are eluted into the resin solution, causing the resin solution to gel.

Also from the above points, the resin composition is preferably a solvent type.

The types of solvents used in the resin composition include hydrocarbons, ketones, esters, ethers, and low molecules (04 or less).
Alcohols or alcohols having secondary and tertiary hydroxyl groups can be used in combination, but alcoholic solvents with high boiling points are not preferred because they inhibit the curing reaction of the resin film.

In curing the resin composition, it is preferable that the main reaction is a urethanization reaction between incyanate as a curing agent and hydroxyl groups in the base resin, but in order to stably store the resin composition before coating, In order to control the reactivity of the isocyanate group of the curing agent, it is necessary to block the incyanate compound. As this blocking method, there is a blocking method in which the blocking group is eliminated during heating and the incyanate group is regenerated.

The incyanate compound is an aliphatic 5-alicyclic (including heterocycle) or aromatic incyanate compound having at least two incyanate groups in one molecule, or a compound obtained by partially reacting these compounds with a polyhydric alcohol. There are compounds that For example, (1) m- or P-phenylene diisocyanate, 2,4- or 2,6-dolylene diisocyanate, or P-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate (2) above (1) alone or with a mixture of compounds.

Reaction chemical formation with polyhydric alcohols (dihydric alcohols such as ethylene glycol and propylene glycol, trihydric alcohols such as glycerin and trimethylolpropane, tetrahydric alcohols such as pentaerythritol, hexahydric alcohols such as sorbitol and dipentaerythritol, etc.) There are compounds in which at least two isocyanate groups remain in one molecule.

In addition, examples of the blocking agent include (1) aliphatic monoalcohols such as methanol, ethanol, propatool, butanol, and octyl alcohol; (2) monoethers such as ethylene glycol and/or diethylene glycol; and (3) phenol, cresol, etc. The aromatic alcohol (4) includes oximes such as acetoxime and methyl ethyl ketone oxime, and by reacting one or more of these with the above-mentioned isocyanate compound, it is possible to obtain an isocyanate compound that is stably blocked at least at room temperature. can.

Such an isocyanate compound is blended into an epoxy resin as a curing agent, and the blending ratio is epoxy resin/curing agent = 9515 to 60/40 (weight ratio of non-volatile content);
Preferably it is 90/10 to 70/30.

Incyanate compounds have water absorption properties, and epoxy resins/
If the curing agent ratio exceeds 90/10, paint adhesion will deteriorate, and this tendency will become even more pronounced when the curing agent ratio exceeds 9015. On the other hand, if it is less than 70/30, the curing of the resin film will be insufficient, corrosion resistance and paint adhesion will deteriorate, especially 6
This tendency becomes even more pronounced when the ratio is less than 0/40.

Furthermore, an alkyl etherified amino resin obtained by reacting formaldehyde with one or more selected from melamine, urea, and benzoguanamine as a curing agent may be used in combination with the incyanate compound.

Although the organic resin is sufficiently cured with the above-mentioned curing agent, it is desirable to use a curing accelerating catalyst in order to further increase the reactivity at low temperatures.

Examples of the curing accelerating catalyst include N-ethylmorpholine, dibrutinsilaurylate, cobalt naphthenate,
Examples include stannous chloride, naphthenic acid, bismuth nitrate, etc.

Furthermore, with the aim of improving paint adhesion, processability, etc., an acrylic, alkyd, or polyester resin may be used in combination with the above resin composition.

In the present invention, corrosion resistance can be further improved by blending silica and/or 11-soluble chromate into the organic resin composition constituting the resin film.

It is presumed that silica dissolves in a trace amount in a corrosive environment, and silicate ions function as a film-forming corrosion inhibitor, thereby exerting the anticorrosion effect.

Here, regarding the amount of silica added to the organic resin, if the weight ratio of organic resin/silica exceeds 90/10, the anticorrosive effect of silica will not be sufficiently exhibited and the corrosion resistance will be poor. On the other hand, if it is less than 40/60, the effect of the organic resin as a binder will be insufficient, and paint adhesion will deteriorate.

The silica used in the present invention includes soft silica (for example, AERO5IL 130 manufactured by Nippon Aerosil Co., Ltd.),
AERO5IL 200, AERO3IL 300, A
ERO5IL 380, AERO5IL R972, A
ERO5IL R811, AERO5IL R805
, AERO5IL R974, etc.), colloidal silica (
For solvent-type organic resins, for example, MA-5, IPA-5T, NBA-5 manufactured by Nichijo Kagaku Kogyo Co., Ltd.
T, IBA-5T, EG-5T, XBA-3T,
ETC-5T, DMAC-5T, etc. Water-dispersible/water-soluble organic resins include, for example, Snowtex 20, Snowtex C, Snowtex N, manufactured by Nichijo Kagaku Kogyo Co., Ltd.
Snowtex O, Snowtex S, etc.), wet silica precipitation method (for example, T-32 (S) manufactured by Tokuyama Soda Co., Ltd.),
K-41, F-80), wet silica gel method (for example, Thyroid 244, Thyroid 150, Thyroid 72, Thyroid 65.5 manufactured by Fuji Davison Chemical Co., Ltd.)
HIELDEX etc.) can be used. It is also possible to use a mixture of one or more of the above silicas.

Considering the finished appearance and corrosion resistance in the electrocoating process of automobiles, silica that is not hydrophobized is preferable to silica that is hydrophobized by substituting silanol groups on the silica surface with methyl groups or the like.

In addition, the hardly soluble chromate added to the resin is thought to suppress corrosion of the aluminum alloy plate through a corrosion protection mechanism similar to that of the chromate layer.

Here, as the amount of poorly soluble chromate added to the organic resin, the weight ratio of organic resin/slightly soluble chromate is 90/10.
If it exceeds this amount, the anticorrosive effect of the hardly soluble chromate will not be sufficiently exhibited, resulting in poor corrosion resistance. On the other hand, if it is less than 40/60, the effect of the organic resin as a binder will be insufficient and paint adhesion will deteriorate.

The sparingly soluble chromic hydrochloric acid used in the present invention includes barium chromate (BaCrO,), strontium chromate (
SrCrO,), calcium chromate (CaCrO,)
, zinc chromate (ZnCrO4-4Zn (Of()z
), potassium zinc chromate (ni2f) 4ZnO・4C
There are fine powders such as rO3.3t (20) and lead chromate (PbCr04).

It is also possible to use a mixture of one or more of the above-mentioned poorly soluble chromates. However, from the perspective of corrosion resistance,
Preferred are barium chromate and strontium chromate, which can be expected to maintain the self-repairing effect of chromate ions over a long period of time.

Moreover, barium chromate is preferable from the viewpoint of minimizing the elution of water-soluble chromium from the organic resin film in the pre-painting treatment process for automobiles.

In the present invention, by adding silica and poorly soluble chromate in a specific ratio to the organic resin composition, the most excellent corrosion resistance can be achieved due to the synergistic effect of the anticorrosion effects of both. That is, the weight ratio of silica and poorly soluble chromate is (a) organic resin/(silica + poorly soluble chromate) = 9
The best corrosion resistance can be obtained when the ratio of (b) silica/poorly soluble chromate is 90/10 to 10/90. Here, if the ratio of organic resin/(silica+slightly soluble chromate) exceeds 90/10, the anticorrosive effect of silica and the sparsely soluble chromate will not be sufficiently exerted, resulting in poor corrosion resistance. On the other hand, if it is less than 40/60, the effect of the organic resin as a binder will be insufficient and paint adhesion will deteriorate. In addition, the silica/poorly soluble chromate ratio is 90/1.
Even if it exceeds 0 or less than 10/90, the synergistic effect will be insufficient and the corrosion resistance will be slightly inferior.

In addition, in the present invention, the above-mentioned silica and/or poorly soluble chromate are the main additive components in the organic resin film, but in addition, surfactants, silane coupling agents, color pigments, and color dyes are also added. , anti-rust pigments (e.g. aluminum dihydrogen tripolyphosphate, aluminum phosphomolybdate,
(e.g., zinc phosphate, etc.), conductive pigments (e.g., iron phosphide, antimony-doped tin oxide, etc.), and lubricants (e.g., polyethylene wax, Teflon, graphite, molybdenum disulfide, etc.). I can do it.

The aluminum alloy plate of the present invention usually has the above-mentioned coating on both sides, but if necessary, the above-mentioned coating can be formed on only one side and the other side is left uncoated (the aluminum alloy surface). Alternatively, it is also possible to form only a chromate film.

〔Example〕

As an aluminum alloy plate for automobile bodies, the aluminum alloy plate is degreased with alkali, washed with water, dried, and subjected to chromate treatment, and then coated with an organic resin composition using a roll coater.
It was coated and baked.

The obtained aluminum alloy plates were tested for corrosion resistance, paint adhesion, weldability, cationic electrodeposition paintability, and scratch resistance. The processing conditions of this example are as follows.

(1) Aluminum Alloy Plate An aluminum alloy plate having a thickness of 1 m shown in Table 1 was used as a treated original plate.

(2) Chromate treatment ■ Sprayed chromate treatment Chromic acid concentration, phosphate ion concentration, zirconium fluoride ion concentration, zinc ion concentration, CS * / Cr3
Treatment solutions with various weight ratios of * and chromic acid/zirconium fluoride ion weight ratios were applied using a roll coater and dried without washing with water. The composition of the treatment liquid is shown in Tables 2 and 3.

The amount of chromate film deposited was adjusted by changing the peripheral speed ratio of the pickup roll/applicator roll/strip of the roll coater.

■Electrolytic chromate treatment Using a treatment solution of chromic anhydride: 30 g/l, sulfuric acid: 0.2 g/l, bath temperature: 40°C, current density: IOA/d
The object to be treated was subjected to cathodic electrolysis treatment using m2, washed with water, and dried.

The amount of chromate film deposited was adjusted by controlling the amount of electricity applied.

■Reactive chromate treatment Chromic anhydride: 50g/l, Phosphorus: 10g/l, N
aF: 0.5 g/1, K2TiF: 4
Using a treatment solution of g/l and bath temperature: 60°C, the object to be treated was sprayed, washed with water, and dried. The amount of chromate film deposited was adjusted by varying the treatment time.

(3) Organic resin composition Table 4 shows the organic resin and curing agent of the organic resin composition in the present invention. Note that Resin A, Resin B, Curing Agent a, and Curing Agent S in Table 4 were created by the methods shown below.

Table 5 shows the silica to be added to the organic resin of the organic resin composition. Further, Table 6 shows sparingly soluble chromates to be added to the organic resin of the organic resin composition.

■Resin A: In a reactor equipped with a stirring device, a reflux condenser, a thermometer, and a liquid dropping device, Epicoat 1009 (1880 g = 0.5 mol) made by Yuka Shell Epoxy ■ and methyl isobutyl ketone/xylene = 1/1 (weight) After adding 1000 g of the mixed solvent (ratio), the mixture was stirred and heated to uniformly dissolve the mixture at the boiling point of the solvent. Next, the mixture was cooled to 70° C., and 70 g of di(n-propanol)amine was added dropwise to the liquid dropper over 30 minutes.

During this time, the reaction temperature was maintained at 70°C. After dropping, 1
The reaction was completed by holding at 20°C for 2 hours. The obtained reaction product is referred to as resin A. The active ingredient of Resin A is 66%.

■Resin B: Add 57 g of pelargonic acid (reagent) and 80 g of xylene to Yuka Shell Epoxy ■ Epicote 1004 (1600 g) in a reaction apparatus equipped with a reflux condenser, stirring device, thermometer, and nitrogen gas blowing device.
The reaction was carried out at ℃ until the acid value of the reactant became approximately O. Next, xylene was removed under reduced pressure to obtain 1 reaction intermediate. This reaction intermediate (1650 g) was added to a reactor equipped with a stirring device, a reflux condenser, a thermometer, and a liquid dropping device.
After adding 000 g of the mixture, the mixture was heated to 100° C., and 65 g of jetanolamine and 30 g of monoethanolamine were added dropwise to the liquid dropper over a period of 30 minutes. After the dropwise addition was completed, the temperature was maintained at 120°C for 2 hours to complete the reaction. The obtained reaction product is referred to as resin B. The active ingredient of resin B is 63
%Met.

■Curing agent a: 250 g of 4,4-diphenylmethane diisocyanate and 50 g of diimbutyl ketone were placed in a reaction apparatus equipped with a thermometer, a stirring device, and a reflux condenser, and after stirring and mixing them uniformly, 184 g of ethylene glycol monoethyl ether was added. The reaction was carried out at 90°C for 2 hours and then at 110°C for 3 hours to obtain a completely urethanized curing agent a. The active ingredient of curing agent a was 89%.

■Curing agent 222g of inphorone diincyanate was placed in a reaction apparatus equipped with two thermometers, a stirrer, and a reflux condenser with a dropping funnel, and 10g of methyl isobutyl ketone was added to it.
After 0 g was added and uniformly dissolved, 88 g of a 50% solution of trimethylolpropane in methyl isobutyl ketone was added dropwise from the dropping funnel into the stirred isocyanate solution maintained at 70° C. over a period of 1 hour. Next, the temperature was further maintained at 70'C for 1 hour, and then at 90°C for 1 hour. Then, add 230g of n-butyl alcohol,
A blocked isocyanate was obtained by reacting at 90°C for 3 hours. This reaction product is used as a curing agent. The active ingredient of the curing agent was 76%.

Tables 7 to 11 show the compositions of the aluminum alloy plates prepared as described above, and Table 11 shows the evaluation results of their corrosion resistance, paint adhesion, weldability, cationic electrodeposition coating properties, and scratch resistance. The results are shown in Tables 1 to 16, respectively. The evaluation method for each characteristic is as follows.

(a) Corrosion resistance test material was coated with cationic electrodeposition coating (20μ) using U-600 manufactured by Nippon Paint ■, and then KPX manufactured by Kansai Paint Co., Ltd.
-36te intermediate coat (3511) L, then top coat with Kansai Paint ■ Lugabake B-531 (35μ)
I did it. Cross-cuts were made in the coating film of these test pieces with a cutter knife, and a compound corrosion test was conducted in which one cycle was [salt spray test, 24 hours → humidity test (25°C, relative humidity 85%), 30 days]. It was cycled and the corrosion resistance was evaluated based on the length of thread rust from the cross cut part.

0: less than 1.0mm Q: 1. More than Ono and less than -2,0+o+n△: 2. O
Un or more -3, OrIn or less It was immersed in ion-exchanged water for 240 hours. Next, take out the test piece and
After being left at room temperature for 4 hours, 100 base lines at 211f11 intervals were cut into the coating film, adhesive tape was applied and peeled off, and the remaining rate of the coating film was evaluated.

O: No peeling O: Less than 3% 683% or more to less than 10% Electrode tip diameter:
Spot welding was performed under the condition of 150R.

Since the electrodes are significantly damaged if sparks occur between the test material and the electrodes, weldability was evaluated under current conditions.

■ = No nisper generation O: Slight spark generation △: Significant spark generation X: Cannot be energized (cannot be welded)
20μ), and the cationic electrodeposition coating properties were evaluated based on the density of cratering.

◎: 0 pcs/dm2 0: 1 pcs/dm2-5 pcs/d, 2 △: 6 pcs/dm2-10 pcs/dm2 ×: 11 pcs/6m2 or more (e) Scratch resistance weighted scratch strength tester Using, under constant load,
A scratch test was performed on the sample material with a sapphire needle (0.05 m + φ), and evaluation was made at the load at which scratches began to be observed.

0: 50 g or more ○: 40 g or more and less than sog Δ: 30 g or more and less than 40 g
.

No. 49, No. 50 are results in which the influence of chromate treatment was investigated.

No. 091 and Nos. 25 to 36 were investigated for the influence of the aluminum alloy plate.

No. 1 and No. 37 to 48 are results of examining the influence of resins blended into organic resin compositions.

Nos. 51 to 56 are results in which the influence of the thickness of the organic film was investigated.

No. 61 and Nos. 57 to 61 were obtained by examining the influence of silica blended into the organic resin composition.

No. 1 and No. 62 to 65 are results in which the influence of chromate added to the organic resin composition was investigated.

Nos. 66 to 69 are results in which the influence of the blending ratio of the organic resin and [silica + chromate] blended into the organic resin composition was investigated.

Nos. 70 to 74 are results in which the influence of the blending ratio of the organic resin and silica blended into the organic resin composition was investigated.

Nos. 75 to 79 are results in which the influence of the blending ratio of the organic resin and chromate blended in the organic resin composition was investigated.

Nos. 80 to 81 examine the influence of the blending ratio of silica and chromate blended in the organic resin composition.

No. 82 is a comparative example in which only chromate treatment was performed.

Table 1 [Aluminum alloy original plate] -■1σ107-N 1 = 1 C □ω1 discharge 0-↑N1
---. β □−□−〜(′″″″″″″″′″″″
″'N′ゝ・He~MIM, MIM 01 load ,-・-・
−・Knee・−・−(−1−・−;−Knee・−(−1−・
-1-1 (Note 1) See Table 1. (Note 2) For coating type chromates, see Tables 2 and 3. For example, "Application 1" is No. 61 in Table 2.
This indicates that the coating type chromate treatment was performed using the treatment solution.

(Note 3) See Table 4 (Note 4) See Table 5 (Note 5) See Table 6 (Note 6) Weight ratio of organic resin and [silica-poorly soluble chromate] in the organic resin composition ( non-volatile content weight ratio).

(Note 7) Weight ratio (nonvolatile content weight ratio) of silica and poorly soluble chromate compounded in an organic resin composition.

〔Effect of the invention〕

As described above, the aluminum alloy plate of the present invention has excellent corrosion resistance, paint adhesion, weldability, and electrocoatability. It also has excellent scratch resistance.

In addition, the aluminum alloy sheet of the present invention can be manufactured using existing surface treatment equipment for steel sheets, so it can achieve the above-mentioned performances without adding new chromate treatment equipment to the existing automobile manufacturing process. It is possible to use an aluminum alloy plate, which is extremely advantageous in terms of cost.

Furthermore, with the aluminum alloy sheet of the present invention, the elution of aluminum into the phosphate treatment solution is suppressed, so even if the steel sheet and aluminum alloy sheet are simultaneously treated in the existing automotive phosphating process, no phosphate treatment will occur. Does not inhibit the formation of acid salt film. Furthermore, when only aluminum alloy plates are used, it is possible to obtain excellent corrosion resistance, paint adhesion, etc. even if the phosphate treatment step is omitted.

Procedural amendment (own ship February 15, 1991 Toshi Uematsu, Commissioner of the Japan Patent Office -1, Indication of the case 1990 Patent Application No. 3389792, Title of invention Aluminum alloy plate with excellent scratch resistance and corrosion resistance and its manufacturing method 3, relationship with the case of the person making the amendment Patent applicant (412)
Nippon Koukan Co., Ltd. 4, Agent Tsuchiya Building, 1-14-5 Kyobashi, Chuo-ku, Tokyo, Yamanashi 03-3535-10505, Detailed description of the invention in the specification subject to amendment 6, Contents of amendment amended as shown in the attached sheet Content 1: In the specification of the present application, page 29, lines 4 to 9 are corrected as follows.

Claims (17)

[Claims] (1) An aluminum alloy plate having excellent scratch resistance and corrosion resistance, which has a chromate layer as a first layer on the surface of the aluminum alloy plate, and an organic resin film as a second layer on top of the chromate layer. (2) Scratch resistance according to claim (1), wherein the chromate layer has a chromate adhesion amount of 10 to 200 mg/m^2 in terms of metallic chromium, and the organic resin film has a thickness of 0.3 to 5 μm. and aluminum alloy plate with excellent corrosion resistance. (3) The aluminum alloy plate with excellent scratch resistance and corrosion resistance according to claim (1) or (2), wherein the organic resin film contains silica in the following ratio (weight ratio) to the organic resin. Organic resin/silica = 90/10 to 40/60 (4) Claim (1) or (4) wherein the organic resin film contains a sparingly soluble chromate in the following ratio (weight ratio) to the organic resin:
2) The aluminum alloy plate having excellent scratch resistance and corrosion resistance. Organic resin/slightly soluble chromate = 90/10 to 40/60 (5) Claim (1) wherein the organic resin film contains silica and poorly soluble chromate in the following ratio (weight ratio) to the organic resin:
) or (2), the aluminum alloy plate having excellent scratch resistance and corrosion resistance. Organic resin/(silica + poorly soluble chromate) = 90/10
~40/60 Silica/slightly soluble chromate =90/10~10/90 (6) Claims (1), (2), (3), (4) or (
5) The aluminum alloy plate having excellent scratch resistance and corrosion resistance. (7) The scratch resistance and the property according to claim (6), wherein the epoxy resin is an epoxy resin having at least one basic nitrogen atom and at least two primary hydroxyl groups added to the terminal end of the resin. Aluminum alloy plate with excellent corrosion resistance. (8) The organic resin composition constituting the organic resin film is composed of an epoxy resin with at least one basic nitrogen atom and at least two primary hydroxyl groups added to the terminal end of the resin, a polyisocyanate compound, and Claim (1) containing at least one curing agent selected from the group consisting of blocked isocyanate compounds in the following ratio (weight ratio):
), (2), (3), (4) or (5), the aluminum alloy plate having excellent scratch resistance and corrosion resistance. Epoxy resin/curing agent = 95/5 to 60/40 (9) A method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance, which comprises subjecting the surface of the aluminum alloy plate to chromate treatment, and after drying, applying an organic resin composition and baking treatment. (10) According to claim (9), the surface of the aluminum alloy plate is subjected to chromate treatment by applying a chromate solution and drying without washing with water, and then applying an organic resin composition and performing a baking treatment. A method for manufacturing an aluminum alloy plate with excellent scratch resistance and corrosion resistance. (11) The method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance according to claim (10), characterized in that a chromate solution having a liquid composition adjusted as shown below is applied. Chromic anhydride: 5-100g/l Phosphate ion: 0.5-20g/l Zirconium fluoride ion: 0.2-4g/l Zinc ion: 0.2-7g/l Cr^5^+/Cr^ 3^+: 3/4 to 3/2 (weight ratio) Chromic acid/zirconium fluoride ion: 10/1 to 1
00/1 (weight ratio) (12) The method according to claim (9), (10) or (11), characterized in that an organic resin composition containing silica in the following ratio (weight ratio of non-volatile content) to organic resin is applied. A method for manufacturing an aluminum alloy plate with excellent scratch resistance and corrosion resistance. Organic resin/silica = 90/10 to 40/60 (13) Claims (9), (10) or The method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance as described in (11). Organic resin/slightly soluble chromate = 90/10 to 40/60 (14) Claims (9) and (1) characterized in that an organic resin composition containing silica and hardly soluble chromate in the following ratio (weight ratio of non-volatile content) to the organic resin is applied.
0) or (11), the method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance. Organic resin/(silica + poorly soluble chromate) = 90/10
~40/60 Silica/slightly soluble chromate =90/10~10/90 (15) Claims (9), (10), (11), (12) wherein the organic resin constituting the organic resin composition is an epoxy resin.
), (13) or (14), the method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance. (16) The scratch resistance and the property according to claim (15), wherein the epoxy resin is an epoxy resin having at least one basic nitrogen atom and at least two primary hydroxyl groups added to the terminal end of the resin. A method for manufacturing aluminum alloy plates with excellent corrosion resistance. (17) At least one organic resin composition is present at the end of the resin.
An epoxy resin to which at least two or more basic nitrogen atoms and at least two or more primary hydroxyl groups have been added, and at least one curing agent selected from the group consisting of polyisocyanate compounds and blocked isocyanate compounds are mixed in the following proportions ( Claims (9) and (10) containing the non-volatile content (weight ratio of non-volatile content)
), (11), (12), (13) or (14), the method for producing an aluminum alloy plate with excellent scratch resistance and corrosion resistance. Epoxy resin/curing agent = 95/5 to 60/40