JP2013202871A - Coated plate of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated plate of an aluminum alloy capable of sufficiently suppressing contact corrosion on a contact face with a copper plate.SOLUTION: A coated plate 1 of an aluminum alloy is used in contact with a steel plate 2. The coated plate 1 of the aluminum alloy includes a substrate 10 composed of aluminum or an aluminum alloy and a resin coated film 11 in which a resin component as a main component is formed on a contact face 101 on at least a steel plate 2 side. The resin coated film 11 is formed laminating a first resin coated film layer 12 and a second resin coated film layer 13 successively from the substrate 10 side, and its total thickness is 1-30 μm. The first resin coated film layer 12 includes a predetermined corrosion suppressing agent, and the second resin coated film layer 13 includes a rust preventive agent composed of ion exchange type silica.

Description

  The present invention relates to an aluminum alloy coated plate used in contact with a steel plate.

Members that combine steel and aluminum (alloy) materials are lightweight, high-strength, and also have resistance to collisions. In recent years, their needs have increased mainly in the field of transportation equipment such as automobiles and railway vehicles. Yes.
Usually, when steel and aluminum are used for automobiles, the steel plate and the aluminum plate are joined by resistance welding or mechanical joining. When the steel plate and the aluminum plate are joined in a butt shape, a gap is unlikely to occur because the joined portions are in close contact. On the other hand, when the steel plate and the aluminum plate are joined by the surface, the joining surface does not completely adhere to each other, and because of distortion of the member itself or spot welding, the gap between the steel plate and the aluminum plate. , Various gaps occur. When the size of the gap (distance between the steel plate and the aluminum plate) is about 0.1 mm, in the electrodeposition coating normally used in the undercoating process at the time of automobile manufacture, the paint does not enter the gap. Unpainted parts occur on the steel and aluminum surfaces.

  When a joining member in which a steel plate and an aluminum plate are joined to each other is used as, for example, a body panel of an automobile, moisture may enter into the above-described gap during use. As a result, different metal contact corrosion (galvanic corrosion) occurs between the unpainted portion of the steel plate and the unpainted portion of the aluminum plate, and the corrosion of aluminum that is lower than steel is promoted. Dissimilar metal contact corrosion means that when different metals such as steel and aluminum are brought into contact with each other, the base metal among the different metals is the anode through the electrolyte formed by the water that has entered the gap between the contact surfaces. This is a phenomenon in which a noble metal acts as a cathode to form a battery, and corrosion of the base metal is promoted. That is, in the dissimilar metal joint structure of steel plate / aluminum plate, if the gap exists, corrosion of aluminum is promoted during use, and the corrosion rate becomes much higher than that of aluminum alone, and damage such as perforation occurs early. Is caused. Therefore, it is necessary to prevent such different metal contact corrosion in members / parts formed by surface bonding of different metals.

Conventionally, the following methods have been proposed as a method for preventing contact corrosion of different metals.
For example, a technique for electrically insulating different kinds of metals via an insulator has been proposed (see Patent Document 1). In addition, a technique has been proposed in which a pre-coated steel plate and a pre-coated aluminum plate pre-coated with an organic resin are used, and these are joined by an adhesive after forming (see Patent Document 2). Moreover, the technique which interposes a Zn-Al-Mg alloy between aluminum material and steel material is proposed (refer patent document 3). In addition, a technique for coating a contact portion of a different metal with a composition containing a nitrite inhibitor or an oxyanion inhibitor has been proposed (see Patent Document 4). Moreover, when joining a steel plate and an aluminum plate, a resin film containing at least one resin selected from polyolefin resin, polyurethane resin, and epoxy resin and silica is formed on the surface of the steel plate side. The technique to do is proposed (refer patent document 5). A technique has been proposed in which a coating film composed of a water-based urethane resin, silica, and a lubricant is formed on the surface of an aluminum material, and the coating film surface is joined to a steel material. (See Patent Document 6).

JP 2008-80394 A Japanese Patent Laid-Open No. 5-50173 JP 2001-11665 A JP-A-4-160169 JP 2011-140067 A JP 2011-156825 A

However, for example, in the technique of electrically insulating between different kinds of metals via an insulator as in Patent Document 1, there are many cases where it is difficult to actually realize because there are structural and manufacturing restrictions. Even so, there is a problem that welding superior in terms of bonding strength cannot be applied. For example, Patent Document 1 describes a method of spot welding after applying an organic resin adhesive in advance to a contact portion of a different metal. However, in this method, the construction takes time and the application state is likely to be non-uniform, which may cause corrosion from the application defect portion.
In addition, in the method of joining with an adhesive after molding processing, for example, as in Patent Document 2, contact corrosion does not occur, but since an adhesive is used for joining, work is troublesome and the joining strength is increased. There is a problem in application to a structural member such as a body panel of an automobile, which is not reliable.

Further, as disclosed in Patent Document 3, in a method in which a Zn—Al—Mg alloy is interposed, a Zn—Al—Mg alloy layer must be formed by means such as plating, which makes the process complicated.
Further, as disclosed in Patent Document 4, the method of coating with a composition containing an inhibitor is effective for suppressing contact corrosion between stainless steel or titanium having a higher potential than steel materials and general steel materials. However, it cannot be applied to suppression of contact corrosion with a metal having a low potential (for example, aluminum).
Further, as in Patent Documents 5 and 6, the method of adding silica to the single layer film has a problem that the continuity of the anticorrosion effect is low and it is difficult to sufficiently suppress the corrosion of aluminum.

  This invention is made | formed in view of this background, and it aims at providing the aluminum alloy coating plate which can fully suppress the contact corrosion in a contact surface with a steel plate.

One aspect of the present invention is an aluminum alloy coated plate used in contact with a steel plate,
A substrate made of aluminum or an aluminum alloy, and a resin film mainly composed of a resin component formed on a contact surface on the steel plate side of the substrate;
The resin coating is formed by laminating a first resin coating layer and a second resin coating layer in order from the substrate side, and the total thickness is 1 to 30 μm,
The first resin coating layer contains at least one corrosion inhibitor selected from the group consisting of benzoate, glutamate, anisidine, glycine, quinolinol, phthalate, adipate, and acetate,
The second resin coating layer is an aluminum alloy coated plate characterized by containing a rust inhibitor made of ion-exchange silica.

In the said aluminum alloy coating board, the said 2nd resin film layer contains the said rust preventive agent which consists of ion-exchange-type silica. Therefore, at the time of flooding, the rust inhibitor contained in the second resin coating layer can play a role of preventing dissolution of the metal component from the steel plate side that contacts the aluminum alloy coated plate. . As a result, corrosion of the substrate made of aluminum or aluminum alloy caused by melting of the metal component from the steel plate side can be prevented.
In addition, when exposed to water, the rust preventive agent composed of ion-exchanged silica elutes into the water from the second resin coating layer and reaches an effective concentration, thereby adsorbing ion-exchanged silica combined with iron on the steel sheet surface. A layer can be formed. As a result, an effect of cathodic protection is obtained, and corrosion of the substrate made of aluminum or aluminum alloy can be suppressed.
Furthermore, since the said rust preventive agent consists of ion exchange type | mold silica, in the said aluminum alloy coating plate, electroconductivity can be produced in the said 2nd resin film layer. Therefore, even if the metal component is dissolved from the steel plate, the second resin coating layer of the aluminum alloy coated plate has conductivity, so that the pinhole effect due to coating film defects is less likely to occur, and local corrosion of aluminum is reduced. can do.

  Moreover, since the said aluminum alloy coating plate has the said 2nd resin film layer containing the said rust preventive agent, as the said steel plate made to contact the said aluminum alloy coating plate, it is using the steel plate which has not performed coating etc. previously. it can. For example, when joining an aluminum alloy coated plate and a steel plate as a door material for automobiles, etc., in order to obtain the strength required as a door material, after joining steel plates of various thicknesses, the aluminum material is joined. There is a case. Even in such a case, since the steel plate in which the coating or the like is not performed and the resin coating layer is not formed can be used, the steel plates can be easily welded to each other.

  Moreover, the said aluminum alloy coating plate has the said resin film formed by laminating | stacking the said 1st resin film layer and the said 2nd resin film layer. Therefore, it is possible to prevent a through hole (pinhole) that is likely to be generated during the formation of the resin film from being completely formed through the resin film. That is, when the resin film is formed by, for example, a roll coater method which is widely used in industry, a coating film defect penetrating the resin film is likely to occur due to entrainment of bubbles in the paint or foaming at the time of solvent volatilization. In the aluminum alloy coated plate, as described above, the resin film is formed by multilayering two or more coating layers, ie, the first resin coating layer and the second resin coating layer. Can be prevented.

  Moreover, the said aluminum alloy coating board has the said 1st resin film layer containing the said corrosion inhibitor. Therefore, for example, even if a defect occurs in the resin film due to contact or handling with a mold during bending by a press or overhang molding, the corrosion inhibitor dissolves in water from the first resin coating layer when exposed to water. The corrosion inhibitor is concentrated in the process of taking out and drying, and a hydrophobic adsorption layer can be formed on the surface of the aluminum alloy coated plate. This adsorption layer contributes to the improvement of the corrosion resistance of the aluminum alloy coated plate, and can suppress the corrosion of the defect occurrence portion.

  Thus, in the said aluminum alloy coating plate, the contact corrosion in a contact surface with a steel plate can fully be suppressed.

Explanatory drawing which shows the cross-section of the aluminum alloy coating board in an Example. Explanatory drawing which shows the cross-section of the structure which made the steel plate and the aluminum alloy coating plate contact in an Example. Explanatory drawing which shows the cross-section of the aluminum alloy coating board which contains the resin bead in the 2nd resin film in an Example. Explanatory drawing which shows the state in which the crosscut part was formed in the coating surface of the resin film of the aluminum alloy coating board in an Example. Explanatory drawing which shows the test piece for a corrosion test in which the coating surface of the resin film of an aluminum alloy coating plate in an Example and a steel plate are faced, and a water retention layer is arrange | positioned among these. Explanatory drawing which shows a mode that an aluminum alloy coating board is folded and processed in an Example by a cross-sectional structure. Explanatory drawing which shows a mode that a convex part is formed in an aluminum alloy coating board by press work in an Example by sectional structure.

Next, a preferred embodiment of the aluminum alloy coated plate will be described.
The aluminum alloy coated plate is preferably used in contact with a galvanized steel plate or a zinc-aluminum plated steel plate. In this case, the effect of suppressing the above-mentioned contact corrosion in the aluminum alloy coated plate becomes more remarkable. The galvanized steel sheet is a steel sheet plated with zinc or an alloy containing zinc as a main component, and the zinc-aluminum plated steel sheet is a steel plate plated with an alloy containing zinc as a main component and further containing aluminum. .
Generally, when a galvanized steel plate or a zinc-aluminum plated steel plate and an aluminum alloy plate are brought into contact with each other, the zinc plated on the galvanized steel plate or the zinc-aluminum plated steel plate, which has a lower potential than aluminum, is dissolved when wet. Iron is easily exposed on the surface. As a result, a substrate made of aluminum or an aluminum alloy, which is less basic than iron, is likely to cause problems such as melting and perforation. However, since the first resin coating layer and the second resin coating layer are formed in the aluminum alloy coated plate, even when the steel plate is made of a galvanized steel plate or a zinc-aluminum plated steel plate, Is less likely to occur and corrosion can be sufficiently suppressed.

The aluminum alloy coated plate is used, for example, to form a bonded structure by bonding to the steel plate. The obtained bonded structure is used as, for example, a body panel such as an automobile door.
The said aluminum alloy coating plate and the said steel plate can be joined in the state which has electrical continuity. Preferably, the aluminum alloy coated plate is used after being mechanically or chemically bonded to an unpainted steel sheet (claim 10). In this case, the weight can be significantly reduced as compared with the case where the structure is assembled with a single steel plate, and a higher strength can be obtained as compared with the case where the structure is assembled with a single aluminum alloy plate. In this case, the above-described excellent contact corrosion inhibiting effect of the aluminum alloy coated plate can be remarkably exhibited. The aluminum alloy coated plate and the steel plate can be joined by caulking, screwing, rivets, an adhesive, or the like, for example.

The aluminum alloy coated plate includes a substrate made of aluminum or an aluminum alloy, and a resin film mainly composed of a resin component formed on a contact surface on the steel plate side of the substrate.
As the substrate, for example, various aluminum alloys such as pure aluminum and 6000 series aluminum can be used.
The resin film can be formed on one side or both sides of the substrate. Moreover, it is preferable that the chemical film is formed in the said resin film formation surface in the said board | substrate. The resin film can be formed on the chemical conversion film.
The chemical conversion film is a film that enhances adhesion between the substrate and the resin film. For example, a chemical conversion film made of phosphate chromate, zirconium phosphate, zirconium oxide, chromate chromate, or the like can be formed.

The resin film is formed by laminating a first resin film layer and a second resin film layer in order from the substrate side. The resin component in the first resin coating layer and the second resin coating layer may be the same or different.
The first resin coating layer and the second resin coating layer are preferably composed mainly of one or more resins selected from the group consisting of epoxy-phenolic resins, epoxy-urea resins, and polyester resins. Item 4).
In this case, the water resistance and workability of the resin coating can be improved. Epoxy-phenol resins, epoxy-urea resins, and polyester resins are also easily available industrially.

The epoxy phenol resin is preferably composed of an epoxy resin having an epoxy equivalent of 145 g / eq or more and less than 450 g / eq and a resol type phenol resin.
When the epoxy equivalent is less than 145 g / eq, the resin is soft and there is a risk that scratches are likely to occur in the resin film during processing. On the other hand, when the epoxy equivalent is 450 g / eq or more, the resin is hard and workability may be reduced.
Further, as the phenol resin, for example, a novolac type phenol resin can be used, but the flexibility of the resin film is lost as compared with the resol type phenol resin, and the workability may be lowered. Therefore, a resol type phenol resin is preferable.

The epoxy-urea resin preferably comprises an epoxy resin having an epoxy equivalent of 145 g / eq or more and less than 450 g / eq and a butylated urea resin.
When the epoxy equivalent is less than 145 g / eq, the resin is soft and there is a risk that scratches are likely to occur in the resin film during processing. On the other hand, when the epoxy equivalent is 450 g / eq or more, the resin is hard and workability may be reduced.

More preferably, the first resin coating layer and the second resin coating layer are mainly composed of a polyester resin. The polyester resin preferably has a number average molecular weight of 5000 to 16000, an elongation at break of 120 to 295%, and a glass transition point of 10 to 60 ° C. (Claim 7).
When the number average molecular weight of the polyester resin is less than 5000, the flexibility of the resin film is lowered, and the processability may be reduced. The number average molecular weight of the polyester resin is more preferably 10,000 or more, and further preferably 13,000 or more. On the other hand, when the number average molecular weight exceeds 16000, the resin becomes soft, and there is a possibility that tacking occurs where the coated plates stick to each other.

Moreover, when the elongation at break of the polyester resin is less than 120%, for example, the resin film cannot follow during drawing, and the resin film may peel off from the substrate. On the other hand, when the elongation at break exceeds 295%, the resin is too soft and the above-described tacking may occur. The breaking elongation of the polyester resin is more preferably 120 to 206%.
The elongation (%) of the polyester resin can be measured by a tensile test of a resin film made of the polyester resin. The ratio of the length of the resin film at the time of fracture after the tensile test to the length of the resin film before the tensile test is expressed as a percentage. The tensile test can be performed at a temperature of 25 ° C., for example.

  Moreover, when the glass transition point of the said polyester resin is less than 10 degreeC, there exists a possibility that the tacking that aluminum alloy coating plates may stick may occur easily. On the other hand, when the glass transition point exceeds 60 ° C., the flexibility of the resin film is lowered, and the workability may be reduced. More preferably, the glass transition point of the polyester resin is 10 to 55 ° C.

The resin film formed by laminating the first resin film layer and the second resin film layer preferably has a total thickness of 1 to 30 μm.
When the thickness is less than 1 μm, the effect of preventing the formation of through holes due to multilayering may be reduced. Moreover, since content of the corrosion inhibitor contained in a resin film decreases, there exists a possibility that an anticorrosion effect may become low. More preferably, the thickness of the resin coating is 12 μm or more in total of the first resin coating layer and the second resin coating layer, and more preferably 15 μm or more. On the other hand, when the thickness exceeds 30 μm, the adhesion between the resin film and the substrate is lowered, and there is a possibility that peeling occurs during processing. Further, even if the thickness is increased beyond 30 μm, the anticorrosion effect is no longer improved, and an effect commensurate with the cost cannot be obtained. More preferably, the thickness of the resin coating is 25 μm or less in total of the first resin coating layer and the second resin coating layer.

  The total thickness of the first resin coating layer and the second resin coating layer is preferably 1 to 30 μm as described above, but the thickness of the first resin coating layer is preferably 0.5 to 15 μm. The thickness of the second resin coating layer is preferably 0.5 to 24 μm. More preferably, the thickness of the first resin coating layer is 6 to 15 μm, and the thickness of the second resin coating layer is 6 to 24 μm. More preferably, the thickness of the second resin coating layer is 10 μm or more, and the thickness of the second resin coating layer is preferably larger than the thickness of the first resin coating layer.

The first resin coating layer contains a corrosion inhibitor. As the corrosion inhibitor, one or more selected from the group consisting of benzoate, glutamate, anisidine, glycine, quinolinol, phthalate, adipate, and acetate can be used. Among these, as a salt, alkali metal salts, such as a sodium salt and potassium salt, or ammonium salt can be used, for example. More specifically, for example, ammonium benzoate, sodium benzoate, sodium glutamate, ammonium phthalate, potassium phthalate, ammonium adipate, sodium acetate, ammonium acetate, potassium acetate and the like can be used.
The corrosion inhibitor has a hydrophobic organic chain portion and a functional group portion that is easily adsorbed on a metal surface. For this reason, the corrosion inhibitor dissolves into the water when it is exposed to water, and the corrosion inhibitor is concentrated during the drying process, so that it is easy to form a hydrophobic adsorption layer on the surface of the substrate. This adsorption layer can improve the corrosion resistance. In particular, when hem processing is performed on the aluminum alloy coated plate, the joint portion of the metal plate has a bag-like structure in the processed portion, and a general electrodeposition paint does not precipitate, and the above-described penetration defects, etc. Although it is difficult to obtain an effective anticorrosion effect at the defect occurrence portion, the corrosion resistance can be improved by forming the adsorption layer because the first resin coating layer contains a corrosion inhibitor.
Preferably, the first resin coating layer preferably contains at least a benzoate as a corrosion inhibitor. In this case, the corrosion inhibition effect can be further improved.

The first resin coating layer preferably contains 1 to 25 parts by mass of the corrosion inhibitor with respect to 100 parts by mass of the resin component in the first resin coating layer.
When the content of the corrosion inhibitor is less than 1 part by mass, the anticorrosion effect is lowered. More preferably, the content of the corrosion inhibitor is 5 parts by mass or more, and more preferably 15 parts by mass or more. On the other hand, when the amount exceeds 25 parts by mass, the corrosion inhibitor foams when the first resin film is formed by baking, for example, and there is a possibility that adhesion may be lowered or corrosion resistance may be lowered.

Moreover, the said 2nd resin film layer contains ion-exchange-type silica as a rust preventive agent. Preferably, calcium ion exchange silica is used.
Specific examples of the ion exchange silica include “Silo Mask 02”, “Silo Mask 35”, “Silo Mask 55”, “Silo Mask 52M”, and W.S. R. Grace & Co. “SHIELDEX” manufactured by Nippon Chemical Industry Co., Ltd. “Powdered sodium silicate No. 1”, “Powdered sodium silicate No. 2”, “Powdered sodium silicate No. 3”, “Sodium metasilicate (9 hydrate)”, “ “Sodium metasilicate (pentahydrate)”, “anhydrous sodium metasilicate”, “granular sodium metasilicate” and the like can be used.

The second resin coating layer preferably contains 1 to 25 parts by mass of the rust inhibitor with respect to 100 parts by mass of the resin component in the second resin coating layer.
When the content of the rust inhibitor is less than 1 part by mass, the anticorrosion effect is lowered. More preferably, the content of the rust inhibitor is 5 parts by mass or more, and more preferably 15 parts by mass or more. On the other hand, when it exceeds 25 mass parts, the said 2nd resin film may harden | cure and there exists a possibility that workability may fall.

The second resin coating layer preferably contains 50 parts by mass or less of resin beads having an average particle diameter of 5 to 130 μm with respect to 100 parts by mass of the resin component in the second resin coating layer. .
In this case, for example, it is possible to prevent a flaw from being generated in the hem processing portion during hem processing.
As the resin beads, a hollow type or a solid (filled) type can be used. The hollow type is desirable from the viewpoint of high cushioning effect and high scratch prevention effect.

  With respect to the resin beads, when the average particle diameter is less than 5 μm, the above-mentioned flaw prevention effect may not be sufficiently obtained. On the other hand, when the average particle diameter exceeds 130 μm, the beads may come into contact with each other at the hem-processed portion, and the coating film may be easily peeled off. The “average particle size” indicates the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.

The content of the resin beads is preferably 50 parts by mass or less with respect to 100 parts by mass of the resin component in the second resin coating layer. When the resin bead exceeds 50 parts by mass, the flexibility of the resin film is lost and the processability may be reduced.
The resin beads are a selective component, and the content thereof may be zero. When the resin beads are added, the content is preferably 1 part by mass or more and more preferably 10 parts by mass or more in order to sufficiently obtain the effect of addition.

When the resin beads are used, preferably, the relationship between the resin beads and the thickness of the second resin coating layer is 0.1 <average particle diameter of the resin beads / thickness of the second resin coating layer. It is preferable to be within the range of <12.
If the ratio of the average particle diameter of the resin beads to the thickness of the second resin coating layer is 0.1 or less, the flaw prevention property of the hem-processed portion may be lowered. On the other hand, when the ratio of the average particle diameter of the resin beads to the thickness of the second resin coating layer is 12 or more, the resin beads may fall off from the second resin coating layer. More preferably, 0.1 <average particle diameter of resin beads / thickness of second resin coating layer <5.

  Examples of the resin beads include “Matsumoto Microsphere F-36”, “Matsumoto Microsphere F-36LV”, “Matsumoto Microsphere F-48”, “Matsumoto Microsphere FN-80GS”, “Matsumoto Microsphere F-36LV”, "Matsumoto Microsphere F-50", "Matsumoto Microsphere F-65", "Matsumoto Microsphere FN-100SS", "Matsumoto Microsphere FN-100S", "Matsumoto Microsphere F-100M", "Matsumoto Microsphere FN-" 100M "," Matsumoto Microsphere FN-100 "," Matsumoto Microsphere FN-105 ", Matsumoto Microsphere FN-180SS," Matsumoto Microsphere FN-180S "," Matsumoto Microsphere FN- “80”, “Matsumoto Microsphere MFL-81GCA”, “Matsumoto Microsphere MFL-HD30CA”, “Matsumoto Microsphere MFL-HD60CA”, “Matsumoto Microsphere FN-80SDE”, “Matsumoto Microsphere F-80DE”, etc. be able to. In addition, “Gantz Pearl GM-0801”, “Gantz Pearl GM-1001”, “Gantz Pearl GM-2001”, “Gantz Pearl GM-2801”, “Gantz Pearl GM-4003”, “Gantz Pearl” of Gantz Kasei Co., Ltd. GM-5003, Gantz Pearl GB-05S, Gantz Pearl GB-08S, Gantz Pearl GB-10S, Gantz Pearl GB-15S, Gantz Pearl GB-22S, Gantz Pearl GB- 28 "," Ganz Pearl GB-55 ", etc. can also be used.

The second resin coating layer is 75 parts by mass of one or more inner waxes selected from lanolin, carnauba, polyethylene, and microcrystalline with respect to 100 parts by mass of the resin component in the second resin coating layer. It is preferable to contain the following (claim 9).
In this case, it is possible to prevent the generation of scratches (scratches) due to contact with the mold during press working or contact during transportation. In addition, workability such as bending can be improved.

When the content of the inner wax exceeds 75 parts by mass, the amount of the inner wax deposited on the surface of the resin coating increases, and the wax may be easily deposited on the mold during molding. More preferably, it is 50 parts by mass or less.
The inner wax is a selective component and the content thereof may be zero. In the case of adding the inner wax, the content is preferably 2 parts by mass or more, more preferably 20 parts by mass or more in order to sufficiently obtain the effect of addition. Further, two or more kinds of the above inner waxes such as carnauba and polyethylene may be mixed and used, and the mixing ratio (weight ratio) can be arbitrarily set. For example, when a mixture of carnauba and polyethylene is used, it is preferably 0: 100 to 75:25 (carnauba: polyethylene).

  The first resin coating layer and the second resin coating layer can be formed by applying and baking a liquid paint containing the above-described blending components.

Example 1
In this example, a plurality of aluminum alloy coated plates (samples 1 to 48) according to examples and comparative examples are prepared and evaluated.
As shown in FIG. 1, an aluminum alloy coated plate 1 according to the example includes a substrate 10 made of an aluminum alloy and a resin coating 11 mainly composed of a resin component formed on at least one surface 101 thereof. As shown in FIG. 2, the aluminum alloy coated plate 1 is used in contact with the steel plate 2. The resin coating 11 is formed on at least the contact surface 101 of the substrate 10 on the steel plate 2 side.

A chemical conversion film (not shown) is formed between the substrate 10 and the resin film 11.
The resin coating 11 is formed by laminating a first resin coating layer 12 and a second resin coating layer 13 in order from the substrate 10 side, and has a total thickness of 1 to 30 μm.
The first resin coating layer 12 contains a resin component as a main component and further contains a corrosion inhibitor.
The second resin coating layer 13 contains a resin component as a main component and further contains a rust preventive agent made of ion-exchange silica.

  Moreover, in this example, as shown in FIG. 3, the 2nd resin coating layer 13 WHEREIN: The aluminum alloy coating board 3 (sample 13-17, sample 34, and sample 35) containing the resin bead 135, 2nd resin Aluminum alloy coated plates (not shown, samples 18 to 20 and sample 43) containing inner wax in the coating layer 13 were produced.

Hereinafter, this example will be specifically described.
In this example, as shown in Tables 1 to 5 below, 48 types of aluminum alloy coated plates (Samples 1 to 48) were produced.
First, an aluminum alloy plate (material: 6083, quality: T4, plate thickness: 1.0 mm) was prepared as the substrate 10. Next, after degreasing the substrate 10, a chemical conversion treatment was performed to form a chemical conversion film. In this example, a reactive chromate film (phosphate chromate film) was formed by phosphoric acid chromate treatment so that the chromium content was 20 mg / m ² . Specifically, the chemical conversion treatment was performed by immersing the sample in the chemical conversion treatment solution, and then dried in an atmosphere of about 100 ° C. The types of chemical conversion coatings formed on the substrate 10 are shown in Tables 1 to 5 below.

Next, the resin film 11 was formed by baking the coating material for 1st resin film layers and the coating material for 2nd resin film layers which contain the composition shown in Table 1-Table 5 on a chemical conversion film, respectively.
The coating material for the first resin coating layer was prepared by mixing components such as a main component resin and a corrosion inhibitor so as to have a blending ratio shown in Tables 1 to 5 described later, and using deionized water as a solvent. .
The coating material for the second resin coating layer is such that the main component resin, the rust inhibitor (rust inhibitor pigment), and other additives (resin beads or inner wax) are mixed in the proportions shown in Tables 1 to 5 below. Mixed and made using deionized water as solvent.
In this example, the coating for the first resin coating layer is applied by the bar coating method, cured by heating at a temperature of 250 ° C. for 30 seconds, and then the coating for the second resin coating layer is applied by the bar coating method. Then, it was cured by heating at a temperature of 250 ° C. for 30 seconds to form a resin film 11 formed by laminating the first resin film layer 12 and the second resin film layer 13.
About the 1st resin coat layer and the 2nd resin coat layer, the kind of resin, the kind of corrosion inhibitor, the kind of rust preventive (rust preventive pigment), other additives, these compounding ratios, the 1st resin coat layer The thickness, the thickness of the second resin coating layer, and the total thickness of the first resin coating layer and the second resin coating layer are shown in Tables 1 to 6 below.

  In Tables 1 to 5 described later, “Polyester A” is a polyester resin having a number average molecular weight of 15000, an elongation at break of 125%, and a glass transition point of 17 ° C. “Polyester B” is a polyester resin having a number average molecular weight of 5000, an elongation at break of 120%, and a glass transition point of 55 ° C. “Polyester C” is a polyester resin having a number average molecular weight of 17,000, an elongation at break of 1200%, and a glass transition point of 10 ° C. “Polyester D” is a polyester resin having a number average molecular weight of 3000, an elongation at break of 2%, and a glass transition point of 40 ° C.

  “Epoxy urea A” is an epoxy-urea resin of an epoxy resin and a butylated urea resin having an epoxy equivalent of 210 g / eq. “Epoxy urea B” is an epoxy-urea resin of epoxy resin and butylated urea resin having an epoxy equivalent of 145 g / eq. “Epoxy urea C” is an epoxy-urea resin of epoxy resin and butylated urea resin having an epoxy equivalent of 430 g / eq. “Epoxy urea D” is an epoxy-urea resin of an epoxy resin and a butylated urea resin having an epoxy equivalent of 135 g / eq. “Epoxy urea E” is an epoxy-urea resin of epoxy resin and butylated urea resin having an epoxy equivalent of 470 g / eq.

  “Epoxyphenol A” is an epoxy-phenolic resin having an epoxy equivalent of 210 g / eq and an epoxy resin and a resol type phenolic resin. “Epoxyphenol B” is an epoxy-phenolic resin having an epoxy equivalent of 145 g / eq and an epoxy resin and a resol type phenolic resin. “Epoxyphenol C” is an epoxy-phenolic resin having an epoxy equivalent of 430 g / eq and an epoxy resin and a resol type phenolic resin. “Epoxyphenol D” is an epoxy-phenol resin having an epoxy equivalent of 135 g / eq and an epoxy resin and a resol type phenol resin. “Epoxyphenol E” is an epoxy-phenolic resin having an epoxy equivalent of 470 g / eq and an epoxy resin and a resol type phenolic resin.

  In Sample 20, a mixture of carnauba and polyethylene was used as the inner wax (see Table 2). The mixing ratio of carnauba and polyethylene in this mixture is 50:50 (carnauba: polyethylene) in mass ratio.

Next, various performance evaluation tests were performed on the aluminum alloy coated plates of Sample 1 to Sample 48.
<Corrosion test>
As shown in FIG. 4, a cross-cut is applied to a part of the coated surface of the resin coating 11 of the aluminum alloy coated plate 1 (3) of each sample based on 7.8 (3) of JIS-K5400 (1979). As a result, the crosscut portion 4 was formed. The cross cut portion 4 is partially formed on the painted surface, and a region where the cross cut portion 4 is not formed is a smooth flat plate portion 5.
Next, as shown in FIG. 5, the coated surface of the resin coating 11 of the aluminum alloy coated plate 1 (3) and the galvanic steel plate 2 (galvalume steel plate) are faced, and a gauze serving as a water retention layer 6 is sandwiched between them. A plate and a galvanic steel plate (galvalume steel plate) were fixed with a metal clip 65 to obtain a test piece.
About this test piece, the salt spray test based on 7.8 of JIS-K5400 (1979) was done. The temperature of the test tank was 35 ° C., the concentration of saline was 5% by mass, and the spraying time was 2 hours. Thereafter, a constant temperature and humidity test was performed. The constant temperature and humidity test was performed by leaving the test piece for 72 hours in a constant temperature and humidity tester having a temperature of 50 ° C. and a humidity of 85% RH. A combination of the salt spray test and the constant temperature and humidity test was defined as one cycle, and each sample was repeated four cycles.
After visually observing the surface of the aluminum alloy coated plate 1 (3) after the test, the depth of focus was measured at a magnification of 100 times with an optical microscope to obtain the corrosion depth. The corrosion depth was measured at three points in the crosscut portion 4 and at any five points in the portion where the crosscut was not made (flat plate portion 5), and the average value was obtained. The results are shown in Tables 6 and 7.

<Coating film adhesion>
As shown in FIG. 6, the aluminum alloy coated plate 1 (3) of each sample was folded 180 ° (0T bend) with the coated surface of the resin coating 11 inside, and sandwiched by a plate having a thickness of 1 mm, it was folded 180 °. Folding (1T bending) was performed in three stages of 180 ° bending (2T bending) across a 2 mm thick plate. That is, the aluminum alloy plate 1 (3) was folded at 180 ° with the coating surface of the resin coating 11 inside so that the distance D in FIG. 6 was 0 mm, 1 mm, or 2 mm. Thereafter, the aluminum alloy coated plate 1 (3) was filled with resin, and the state of the resin coating 11 was observed from the cross section. If there was no peeling of the resin coating 11, it was determined to be acceptable, and the case where peeling was observed was regarded as unacceptable. The results are shown in Tables 6 and 7.

<Moldability>
As shown in FIG. 7, the resin film 11 is subjected to press working for forming a convex portion 18 projecting partly opposite to the surface on which the resin film 11 is formed on the aluminum alloy coated plate 1 (3) of each sample. Perform until breaking and measure the molding height at break.
Specifically, as shown in FIG. 7, the aluminum alloy coated plate 1 (3) of each sample was sandwiched and constrained between a die 71 of the press machine 7 and a wrinkle presser 72 with a wrinkle presser load of 40 kN. The die 71 is provided with a hole 710 through which the punch 73 passes. Then, as shown in FIG. 7, the punch 73 is brought into contact with the surface of the aluminum alloy coated plate 1 (3) where the resin coating 11 is formed, and the punch 103 is pushed up into the hole 710 of the die 71, whereby the aluminum alloy coated plate 1. (3) was made to project in an inverted U shape on the side opposite to the side on which the resin coating 11 was formed, and a convex portion 18 that partially projected to the coating layer forming side was formed on the aluminum alloy coated plate 1 (3). And the punch 73 was raised until the resin film 11 of the aluminum alloy coating board 1 (3) fractured | ruptured, and the raise height of the punch at the time of a fracture | rupture was measured. The results are shown in Tables 6 and 7. It preferably has a moldability of a molding height of 18 cm or more.
In the pressing process, a commercially available pressing oil as a lubricant is applied to the surface on which the resin film 11 is formed, a wrinkle holding load: 40 kN, a punch diameter φ50 mm, r: 25 mm, a punch pushing speed: 120 mm / min, The temperature was 25 ° C.

<Wax accumulation>
The press work until the resin film 11 in the moldability evaluation test was broken was repeated 20 times. Then, the tip of the punch 73 of the press machine 7 was observed with a magnifying glass (magnification 4 times) to check for the presence of wax accumulation. A case where no wax accumulation was observed was evaluated as acceptable, and a case where wax accumulation was observed was evaluated as unacceptable. The results are shown in Tables 6 and 7.

<Pencil hardness>
The pencil hardness of the resin coating on the aluminum alloy coated plate of each sample was measured according to the pencil scratch test specified in JIS-K5400 (1979). The results are shown in Tables 6 and 7. The pencil hardness is preferably 2H or more.

  As is known from Tables 1 to 7, a thickness of 1 to 30 μm consisting of a first resin coating layer 12 containing a corrosion inhibitor and a second resin coating layer 13 containing a rust inhibitor made of ion-exchange silica. It can be seen that the aluminum alloy coated plate 1 (3) having the resin coating 11 formed on the substrate 10 made of an aluminum alloy can sufficiently suppress the contact corrosion with the steel plate (see FIG. 1).

As shown in FIGS. 1-3, in the aluminum alloy coating board 1 (3) concerning the Example of this example, the 2nd resin film layer 13 contains the rust preventive agent which consists of ion-exchange-type silica. Therefore, when the aluminum alloy coated plate 1 (3) is wet, the rust preventive agent contained in the second resin coating layer 13 is zinc from the steel plate 2 side with which the aluminum alloy coated plate 1 (3) is contacted. Dissolution of the metal component can be prevented, and iron can be prevented from being exposed to the surface. As a result, it is possible to prevent corrosion of the substrate 10 made of aluminum or aluminum alloy caused by melting of the metal component from the steel plate 2 side.
Further, at the time of flooding, the rust preventive agent made of ion exchange type silica is eluted from the second resin coating layer 13 into the water and reaches an effective concentration, so that the ion exchange silica adsorption combined with iron on the surface of the steel plate 2 is achieved. A layer can be formed. As a result, an effect of cathodic protection is obtained, and corrosion of the substrate 10 made of aluminum or an aluminum alloy can be suppressed.
Furthermore, since the rust preventive agent is made of ion exchange type silica, the second resin coating layer 13 can be made conductive in the aluminum alloy coated plate 1 (3). Therefore, even if the metal component is dissolved from the steel plate 2, the second resin coating layer 13 of the aluminum alloy coated plate 1 (3) is conductive, so that the pinhole effect due to coating film defects is less likely to occur. Local corrosion can be reduced.

  In addition, since the aluminum alloy coated plate 1 (3) has the second resin coating layer 13 containing a rust preventive agent, the steel plate (2) to be brought into contact with the aluminum alloy coated plate 1 (3) is previously coated. An unpainted steel plate 2 that is not coated can be used. For example, when joining an aluminum alloy coated plate 1 (3) and a steel plate 2 as an application for automobile door materials, etc., after welding steel plates of various thicknesses in order to obtain the strength required as a door material. In some cases, it may be joined with an aluminum material. Even in such a case, since the steel plate 2 on which no coating or the like is performed and the resin coating layer is not formed can be used, the steel plates 2 can be easily welded to each other.

  The aluminum alloy coated plate 1 (3) has a resin film 11 formed by laminating a first resin film layer 12 and a second resin film layer 13. Therefore, it is possible to prevent the through holes 120 and 130 (pinholes 120 and 130) that are likely to occur when the resin coating 11 is formed from being completely formed through the resin coating 11. That is, when the resin film 11 is formed by, for example, a roll coater method that is widely used in industry, a coating film defect penetrating the resin film 11 is likely to occur due to entrainment of bubbles in the paint or foaming when the solvent volatilizes. In the aluminum alloy coated plate 1 (3) according to the example, as described above, the resin coating 11 is formed by multilayering two or more coating layers of the first resin coating layer 12 and the second resin coating layer 13. Therefore, the occurrence of penetration defects can be prevented.

  Moreover, the aluminum alloy coating board 1 (3) has the 1st resin film layer 12 containing a corrosion inhibitor. Therefore, for example, even if a defect occurs in the resin film 11 due to contact with the mold or handling during bending by a press or overhang molding, the corrosion inhibitor dissolves into the water from the first resin film layer 12 when wet. In the course of drying, the corrosion inhibitor is concentrated, and an adsorption layer having hydrophobicity can be formed on the surface of the aluminum alloy coated plate 1 (3). This adsorption layer contributes to the improvement of the corrosion resistance of the aluminum alloy coated plate, and can suppress the corrosion of the defect occurrence portion.

  Thus, in the aluminum alloy coating board 1 (3) concerning an Example, the contact corrosion in a contact surface with the steel plate 2 can fully be suppressed.

DESCRIPTION OF SYMBOLS 1 Aluminum alloy coating board 10 Board | substrate 11 Resin film 12 1st resin film 13 2nd resin film

Next, the resin film 11 was formed by baking the coating material for 1st resin film layers and the coating material for 2nd resin film layers which contain the composition shown in Table 1-Table 5 on a chemical conversion film, respectively.
The coating material for the first resin coating layer was prepared by mixing components such as a main component resin and a corrosion inhibitor so as to have a blending ratio shown in Tables 1 to 5 described later, and using deionized water as a solvent. .
The coating material for the second resin coating layer is such that the main component resin, the rust inhibitor (rust inhibitor pigment), and other additives (resin beads or inner wax) are mixed in the proportions shown in Tables 1 to 5 below. Mixed and made using deionized water as solvent.
In this example, the coating for the first resin coating layer is applied by the bar coating method, cured by heating at a temperature of 250 ° C. for 30 seconds, and then the coating for the second resin coating layer is applied by the bar coating method. Then, it was cured by heating at a temperature of 250 ° C. for 30 seconds to form a resin film 11 formed by laminating the first resin film layer 12 and the second resin film layer 13.
About the 1st resin coat layer and the 2nd resin coat layer, the kind of resin, the kind of corrosion inhibitor, the kind of rust preventive (rust preventive pigment), other additives, these compounding ratios, the 1st resin coat layer The thickness, the thickness of the second resin coating layer, and the total thickness of the first resin coating layer and the second resin coating layer are shown in Tables 1 to 5 described later.

Claims (10)

An aluminum alloy coated plate used in contact with a steel plate,
A substrate made of aluminum or an aluminum alloy, and a resin film mainly composed of a resin component formed on a contact surface on the steel plate side of the substrate;
The resin coating is formed by laminating a first resin coating layer and a second resin coating layer in order from the substrate side, and the total thickness is 1 to 30 μm,
The first resin coating layer contains at least one corrosion inhibitor selected from the group consisting of benzoate, glutamate, anisidine, glycine, quinolinol, phthalate, adipate, and acetate,
The said 2nd resin coating layer contains the rust preventive agent which consists of ion exchange type | mold silica, The aluminum alloy coating board characterized by the above-mentioned.   2. The aluminum alloy coated plate according to claim 1, wherein the first resin coating layer contains 1 to 25 parts by mass of the corrosion inhibitor with respect to 100 parts by mass of the resin component in the first resin coating layer. An aluminum alloy coated plate characterized by   The aluminum alloy coating plate according to claim 1 or 2, wherein the second resin coating layer contains 1 to 25 parts by mass of the rust inhibitor with respect to 100 parts by mass of the resin component in the second resin coating layer. An aluminum alloy coated plate characterized by:   The aluminum alloy coating plate as described in any one of Claims 1-3 WHEREIN: The said 1st resin coating layer and the said 2nd resin coating layer are the group which consists of an epoxy-phenol resin, an epoxy- urea resin, and a polyester resin. An aluminum alloy coated plate comprising as a main component at least one resin selected from the group consisting of:   5. The aluminum alloy coated plate according to claim 4, wherein the epoxy-phenol resin comprises an epoxy resin having an epoxy equivalent of 145 g / eq or more and less than 450 g / eq, and a resol type phenol resin. Board.   5. The aluminum alloy coated plate according to claim 4, wherein the epoxy-urea resin comprises an epoxy resin having an epoxy equivalent of 145 g / eq or more and less than 450 g / eq and a butylated urea resin. Board.   5. The aluminum alloy coated plate according to claim 4, wherein the polyester resin has a number average molecular weight of 5000 to 16000, an elongation at break of 120 to 295%, and a glass transition point of 10 ° C. to 60 ° C. Alloy painted board.   The aluminum alloy coated plate according to any one of claims 1 to 7, wherein the second resin coating layer has an average particle diameter of 5 to 100 parts by mass of the resin component in the second resin coating layer. An aluminum alloy coated plate containing 50 parts by mass or less of 130 μm resin beads.   The aluminum alloy coated plate according to any one of claims 1 to 8, wherein the second resin coating layer is formed of lanolin, carnauba, polyethylene with respect to 100 parts by mass of the resin component in the second resin coating layer. And 75 parts by mass or less of one or more types of inner wax selected from microcrystalline.   The aluminum alloy coated plate according to any one of claims 1 to 9, wherein the aluminum alloy coated plate is used after being mechanically or chemically bonded to an uncoated steel plate.

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