JP2018188713A - Aluminum alloy coated sheet and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy coated sheet high in adhesion between an aluminum alloy sheet and a coating layer, and a method of manufacturing the same.SOLUTION: An aluminum alloy coated sheet comprises an aluminum alloy layer, a coating layer in contact with the aluminum alloy layer, and a hydrate film layer formed on a coating layer-side surface of the aluminum alloy layer. The hydrate film layer comprises (a) a dense first layer consisting principally of aluminum, and (b) a porous second layer positioned more on the side of the coating layer than the fist layer and including magnesium and aluminum. The first layer and the second layer are 500-1,000 nm thick, respectively. The mass ratio of the aluminum to the magnesium of the second layer is 0.6-1.4.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an aluminum alloy coated plate and a manufacturing method thereof.

  The aluminum alloy plate has features such as being lightweight, having appropriate mechanical properties, aesthetics, molding processability, corrosion resistance, and excellent elution resistance, so various containers, structural materials, Widely used for machine parts.

A resin paint may be applied to the surface of the aluminum alloy plate in order to further improve the corrosion resistance and the dissolution resistance, the appearance, or the scratch resistance.
Prior to coating, a surface treatment is performed on the surface of the aluminum alloy plate. In Patent Document 1, as a base treatment, an aluminum alloy plate is immersed in an aqueous solution of boric acid, borate, phosphate, adipate, etc., and subjected to electrolytic treatment, so that the surface of the aluminum alloy plate is nonporous. A method of forming an anodized film is disclosed.

JP-A-8-283990

However, even when the non-porous anodic oxide film disclosed in Patent Document 1 is formed, the adhesion between the aluminum alloy plate and the coating film layer may be insufficient.
One aspect of the present disclosure provides an aluminum alloy coated plate having high adhesion between an aluminum alloy plate and a coating layer, and a method for producing the same.

  One aspect of the present disclosure includes an aluminum alloy layer, a coating layer in contact with the aluminum alloy layer, and a hydrate coating layer formed on a surface of the aluminum alloy layer on the coating layer side, The hydrate film layer includes (a) a dense first layer mainly composed of aluminum, and (b) a porous film that is located closer to the coating film layer than the first layer and contains magnesium and aluminum. The thickness of the first layer and the second layer is 500 to 1000 nm, respectively, and the mass ratio of aluminum to magnesium in the second layer is 0.6 to 1.4. Alloy coated plate.

In the aluminum alloy coated plate which is one embodiment of the present disclosure, the adhesion between the aluminum alloy plate and the coating layer is high.
Another aspect of the present disclosure is a method for producing an aluminum alloy coated plate according to one aspect of the present disclosure, in which a magnesium chloride having a concentration of 5.0 to 11.0 g / L and a concentration of 0.2 to 0.00. The aluminum alloy layer is hydrothermally denatured using a mixed solution containing 6 g / L sodium bicarbonate and sodium sulfate having a concentration of 1.0 to 5.0 g / L and having a temperature of 75 ° C. or higher. By this, it is a manufacturing method of the aluminum alloy coating board which forms the said hydrate film | membrane layer.

  According to the method for manufacturing an aluminum alloy coated plate according to another aspect of the present disclosure, an aluminum alloy coated plate having high adhesion between the aluminum alloy plate and the coating layer can be manufactured.

It is sectional drawing showing the example of the form of an aluminum alloy coating board.

An embodiment of the present disclosure will be described.
<Aluminum alloy layer>
The aluminum alloy layer is made of an aluminum alloy. A hydrate film layer is formed on the surface of the aluminum alloy layer. The hydrate film layer will be described later.

  The aluminum alloy is not particularly limited. For example, pure aluminum 1000 series alloy, Al-Cu series, Al-Cu-Mg series 2000 series alloy, Al-Mn series 3000 series alloy, Al-Si series 4000 series. Alloy, Al-Mg-based 5000 alloy, Al-Mg-Si-based 6000-based alloy, Al-Zn-Mg-Cu-based, Al-Zn-Mg-based 7000-based alloy, Al-Fe-based 8000-based alloy Etc. Among these alloys, 1000 series alloys, 3000 series alloys, and 5000 series alloys are preferable.

  The aluminum alloy layer provided in the aluminum alloy coated plate of the present disclosure may be obtained by, for example, subjecting the above-described aluminum alloy to various tempering treatments such as solution treatment and aging treatment.

<Hydrate film layer>
The hydrate film layer is formed, for example, by subjecting an aluminum alloy layer to hot water denaturation treatment. The hydrate film layer includes a first layer and a second layer. The hydrate film layer may be composed of the first layer and the second layer, or may further include another layer.

  The second layer is located closer to the coating layer than the first layer. The first layer is a dense layer mainly composed of aluminum. The first layer may be a layer made of aluminum, or may be a layer containing a smaller amount of other components than aluminum.

The dense means a high-density structure that is not a structure having a hollow or a hole.
The thickness of the first layer is 500 to 1000 nm. By being 500 nm or more, the corrosion resistance of the aluminum alloy coated plate is further improved. By being 1000 nm or less, the hydrate film layer is not easily destroyed, and the adhesion of the hydrate film layer to the aluminum alloy layer is further improved. The measuring method of the thickness of the first layer is the measuring method described in Examples described later.

  The second layer is a porous layer containing magnesium and aluminum. The second layer may be a layer made of magnesium and aluminum, or may be a layer containing other components.

  The thickness of the second layer is 500 to 1000 nm. The measuring method of the thickness of the second layer is the measuring method described in Examples described later. By being 500 nm or more, the corrosion resistance of the aluminum alloy coated plate is further improved. Moreover, the coating material which comprises a coating-film layer is fully contained in the void | hole of a 2nd layer because it is 500 nm or more. As a result, the adhesion of the coating layer to the aluminum alloy layer is further improved. When the thickness of the second layer is 1000 nm or less, the second layer is not easily broken, and the adhesion of the hydrate film layer to the aluminum alloy layer is further improved.

  The mass of magnesium contained in the second layer is Wm. Wa represents the mass of aluminum contained in the second layer. The mass ratio R of aluminum to magnesium in the second layer is Wa / Wm. The measuring method of mass ratio R is the measuring method described in the Example mentioned later. The mass ratio R is 0.6 to 1.4.

  When the mass ratio R is 0.6 or more, the corrosion resistance of the hydrate film layer is further improved. Moreover, when the mass ratio R is 0.6 or more, the hydrate film layer is not easily brittle, and the adhesion of the hydrate film layer to the aluminum alloy layer is further improved. When the mass ratio R is 1.4 or less, the corrosion resistance of the aluminum alloy coated plate is further improved.

  An example of the form of the aluminum alloy coated plate is shown in FIG. For example, as shown in FIG. 1, the aluminum alloy coating plate 1 includes an aluminum alloy layer 3 and a coating layer 5 in contact therewith. The aluminum alloy layer 3 includes a hydrate coating layer 7 formed on the surface of the coating layer 5 side. The hydrate film layer 7 includes a first layer 9 and a second layer 11. The second layer 11 is located closer to the coating film layer 5 than the first layer 9.

<Method for producing aluminum alloy coated plate>
For example, a pretreatment can be performed on the aluminum alloy layer before the hot water modification treatment described later. The pretreatment is not particularly limited, and examples thereof include a pretreatment for removing oil and fat adhering to the surface of the aluminum alloy layer and a pretreatment for removing a heterogeneous oxide film on the surface of the aluminum alloy layer.

  As the pretreatment, for example, there is a method of first performing a degreasing treatment with a weak alkaline degreasing solution, then performing an alkali etching with a sodium hydroxide aqueous solution, and then performing a desmut treatment in a nitric acid or sulfuric acid aqueous solution. As another pretreatment, first, a method of performing a degreasing treatment and then performing an acid cleaning can be mentioned.

  A hydrate film layer can be formed by subjecting the aluminum alloy layer to a hydrothermal modification treatment. In the hot water denaturation treatment, for example, an aluminum alloy layer is immersed in the mixed solution. The mixed solution used for the hot water denaturation treatment includes magnesium chloride, sodium hydrogen carbonate, and sodium sulfate. Magnesium chloride contributes to the formation of the second layer. The solute in the mixed solution may be only the above three kinds, or may further contain other solutes. The solvent in the mixed solution is, for example, water. As the water, for example, industrial water, tap water, ground water, deionized water, distilled water and the like can be used.

  The concentration of magnesium chloride in the mixed solution is 5.0 to 11.0 g / L. By being 5.0 g / L or more, a hydrate film layer having a sufficient thickness can be formed. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved, and the adhesion between the aluminum alloy layer and the coating layer is further improved.

  When the concentration of magnesium chloride in the mixed solution is 11.0 g / L or less, the corrosion resistance of the aluminum alloy coated plate is further improved, and the adhesion between the aluminum alloy layer and the coating layer is further improved. The reason is that when the concentration of magnesium chloride in the mixed solution is 11.0 g / L or less, the mass ratio R in the second layer is unlikely to become excessively small.

  The pH in the mixed solution can be, for example, 9.2 to 11.0. The pH in the mixed solution can be adjusted, for example, by adding a sodium hydroxide solution or the like. When pH in a liquid mixture is 9.2 or more, the effect of magnesium chloride is accelerated | stimulated and the formation rate of a hydrate film | membrane layer increases. When the pH is 11.0 or less, the dissolution rate of aluminum is difficult to increase, and a sufficient hydrate film layer having a sufficient thickness can be formed. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved.

  The concentration of sodium bicarbonate in the mixed solution is 0.2 to 0.6 g / L. Sodium bicarbonate contributes to the formation of the second layer. When the concentration of sodium bicarbonate is 0.2 g / L or more, the effect of forming the second layer is further improved, and a hydrate film layer having a sufficient thickness can be formed. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved, and the adhesion between the aluminum alloy layer and the coating layer is further improved.

  When the concentration of sodium hydrogen carbonate is 0.6 g / L or less, the surface of the aluminum alloy layer is not easily covered with carbonate, and elution of aluminum is difficult to be inhibited. Therefore, the growth of the hydrate film layer is hardly inhibited. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved, and the adhesion between the aluminum alloy layer and the coating layer is further improved.

  The concentration of sodium sulfate in the mixed solution is 1.0 to 5.0 g / L. Sodium sulfate contributes to growth of the hydrate film layer and contributes to an increase in the aluminum concentration in the hydrate film layer. When the concentration of sodium sulfate is 1.0 g / L or more, the above-described effect is further enhanced. When the concentration of sodium sulfate is 5.0 g / L or less, the mass ratio R in the second layer is unlikely to be excessive. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved.

  When performing the hydrothermal modification treatment, the higher the temperature of the mixed solution, the faster the formation rate of the hydrate film layer and the thicker the hydrate film layer. The temperature of the mixed solution is preferably 75 ° C. or higher, more preferably 90 ° C. or higher, and particularly preferably 95 ° C. or higher.

  When the temperature of the mixed solution is 75 ° C. or higher, the hydrate film layer can be made thicker. As a result, the corrosion resistance of the aluminum alloy coated plate is further improved, and the adhesion between the aluminum alloy layer and the coating layer is further improved.

  The treatment time for the hot water denaturation treatment is not particularly limited, but the longer the time, the thicker the hydrate film layer can be formed. The treatment time can be, for example, 5 to 60 minutes. When the treatment time is within this range, the hydrate film layer can be made sufficiently thick.

After the hot water modification treatment, for example, steam heating treatment may be performed on the aluminum alloy layer. The steam heat treatment contributes to further formation of the hydrate film layer, and particularly contributes to further formation of the first layer. For example, the first layer can be made thicker by steam heat treatment, and the thickness of the first layer can be 500 to 1000 nm.
<Coating layer>
The coating layer can be formed, for example, by painting a paint. An example of the paint is a resin paint. Examples of resin coatings include general resins such as epoxy resins, epoxy / acrylic resins, polyester resins, vinyl chloride resins, epoxy / urea resins, epoxy / phenol resins, and water-based solvents such as water or cyclohexanone, butyl cellosolve, etc. And a resin paint dissolved or dispersed in the organic solvent.

  For example, a painted resin paint can be baked. The baking conditions are, for example, 150 to 300 ° C. and 10 to 60 seconds. For baking, for example, a general heating method, dielectric heating method, or the like can be used.

  Examples of the coating method that can be used include a bar coater method, a roll coater method, an electrostatic coating method, a spray coating method, a roll squeeze method, a chemicoater method, an air knife method, a dipping method, and a spray method. If necessary, multilayer coating such as undercoating, intermediate coating, and topcoating may be performed.

<Example>
Hereinafter, the present disclosure will be specifically described by way of examples. However, the present examples are only examples, and do not limit the present disclosure.

1. Formation of Hydrate Film Layer A JIS5182 aluminum alloy plate (plate thickness 0.26 mm) was prepared. This aluminum alloy plate corresponds to the aluminum alloy layer.

  The following pretreatment was performed on the aluminum alloy plate. The degreasing agent was diluted with water to prepare an alkaline degreasing solution having a concentration of 2% by mass. The degreasing agent is Surf Cleaner 420N2 (trade name) manufactured by Nippon Paint Surf Chemicals. The aluminum alloy plate was immersed in a degreasing solution at 60 ° C. for 10 seconds to be alkaline degreased and washed with water.

Next, the aluminum alloy plate was immersed in a dilute sulfuric acid aqueous solution for 5 seconds for acid treatment, and further washed with water. The concentration of the dilute sulfuric acid aqueous solution is 0.3%, and the temperature is 50 ° C.
Next, hot water denaturation treatment was performed on the aluminum alloy plate. The hot water denaturing treatment is a treatment of immersing the aluminum alloy plate in a mixed solution containing magnesium chloride, sodium hydrogen carbonate, and sodium sulfate.

  The hydrothermal modification treatment was performed under various conditions with respect to the composition of the mixed solution, the temperature of the mixed solution, and the treatment time. Table 1 shows the conditions for the hydrothermal denaturation treatment. “Processing temperature” in Table 1 means the temperature of the mixed solution.

2. Measurement of the thickness of the hydrate film layer The thickness of the hydrate film layer formed in each Example and each Comparative Example was measured as follows. First, the aluminum alloy plate on which the hydrate film layer was formed was cut using an ultramicrotome to prepare a thin sample having a thickness of about 100 nm. The cutting direction is parallel to the thickness direction of the aluminum alloy plate. Next, the thin piece sample was observed by TEM. The thickness of the first layer was measured at arbitrary 10 points in the observation field (1 μm × 1 μm), and the average value thereof was taken as the thickness of the first layer. Further, the thickness of the second layer was measured at arbitrary 10 points in the observation field (1 μm × 1 μm), and the average value thereof was taken as the thickness of the second layer. The measurement results are shown in Table 1 above.

Further, the morphology of the first layer and the second layer was observed during TEМ observation, and it was confirmed that the first layer was a dense layer, and that the second layer was a porous layer.
3. Measurement of Mass Ratio R For each example and each comparative example, the mass ratio R was measured as follows. First, glow discharge emission spectroscopic analysis was performed on the aluminum alloy plate, and the relationship between the depth from the surface of the aluminum alloy plate and the intensity of the aluminum spectrum was obtained. In addition, the relationship between the depth from the surface of the aluminum alloy plate and the intensity of the magnesium spectrum was obtained.

  Next, the spectrum of aluminum was integrated from the surface of the aluminum alloy plate to a depth corresponding to the thickness of the second layer. The magnesium spectrum was integrated from the surface of the aluminum alloy plate to a depth corresponding to the thickness of the second layer. The thickness of the second layer is a value obtained by TEM observation. A value obtained by dividing the value obtained by integrating the aluminum spectrum by the value obtained by integrating the magnesium spectrum was defined as a mass ratio R. The calculated mass ratio R is shown in Table 1 above.

4). Formation of Coating Layer In each example and each comparative example, a solvent paint mainly composed of a polyester resin was applied to an aluminum alloy plate on which a hydrate coating layer was formed at a coating amount of 60 mg / dm ^2. Bake at 30 ° C. for 30 seconds. As a result, a coating layer in contact with the aluminum alloy plate was formed, and an aluminum alloy coated plate was completed.

5. Evaluation of aluminum alloy coated plate The aluminum alloy coated plate of each Example and each Comparative Example was evaluated as follows.
(5-1) Corrosion resistance test A scratch reaching the aluminum alloy plate was made on the surface of the coating layer using a cutter. Next, the aluminum alloy coated plate was immersed in a mixed aqueous solution containing 0.5% by mass sodium chloride and 1% by mass citric acid at 70 ° C. for 72 hours. Next, the width of corrosion (hereinafter referred to as “corrosion width”) that occurred in the scratched portion of the coating layer was measured. And according to the corrosion width | variety, the following standards evaluated the corrosion resistance of the aluminum alloy coating board. The evaluation results are shown in Tables 2 and 3.

○: Corrosion width is less than 0.3 mm.
X: Corrosion width is 0.3 mm or more.

(5-2) Adhesion test The adhesion of the coating layer was evaluated by a cross-cut adhesion test according to JIS-K5400. Specifically, the number of remaining portions after peeling of the tape among 100 grids was measured. And the adhesiveness of the coating layer was evaluated according to the following criteria according to the number of remaining portions. The evaluation results are shown in Tables 2 and 3 above.

○: The number of remaining locations is 80 or more.
X: The number of remaining locations is less than 80.
(5-3) Post-processing adhesion test 50 mg / m ² of a commercially available silicon-based lubricant was applied to both surfaces of the aluminum alloy coated plate. Next, the aluminum alloy coated plate was drawn (cap diameter = 38 mm, cap height = 18 mm) by a cap molding machine. Next, perforation processing and screw processing were sequentially performed on the aluminum alloy coated plate.

  After the retort (125 ° C. × 30 minutes), the peeled state of the coating layer at the perforation part, the lower end of the cap, and the bead part was visually observed with respect to the cap obtained as described above. The ratio of the length of the separation occurrence site to the total length of the perforation part, the lower end of the cap, and the bead part (hereinafter referred to as the generation site ratio) was recorded in%. And according to the generation | occurence | production site | part ratio, the post-process adhesiveness was evaluated by the following references | standards. The evaluation results are shown in Tables 2 and 3 above.

○: The ratio of the occurrence site is 10% or less.
X: Generation site ratio exceeds 10%.
(5-4) Comprehensive evaluation When the results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were all “◯”, the comprehensive evaluation was “◯”. In other cases, the overall evaluation was “x”. The evaluation results are shown in Tables 2 and 3 above.

As shown in Table 2, in Examples 1 to 21, the overall evaluation was “◯”.
On the other hand, as shown in Table 3, in Comparative Examples 1 and 2, the evaluation results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were “x”. This is presumably because the thickness of the second layer became insufficient because the concentration of magnesium chloride in the mixed solution used for the hot water denaturation treatment was low.

  In Comparative Example 3, the evaluation results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were “x”. This is presumably because the second layer became excessively thick because the concentration of magnesium chloride in the mixed solution used for the hot water denaturation treatment was high.

  In Comparative Examples 4 and 5, the evaluation results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were “x”. This is presumably because the thickness of the second layer became insufficient because the concentration of sodium bicarbonate in the mixed solution used for the hot water denaturation treatment was low.

  In Comparative Example 6, the evaluation result of the corrosion resistance test was “x”. This is presumed to be because the hydrate film layer was not sufficiently formed because the concentration of sodium bicarbonate in the mixed solution used for the hot water denaturation treatment was high.

  In Comparative Examples 7 and 8, the evaluation result of the corrosion resistance test was “x”. This is presumably because the mass ratio R in the second layer was excessively low because the concentration of sodium sulfate in the mixed solution used for the hot water denaturation treatment was low.

  In Comparative Examples 9 and 10, the evaluation results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were “x”. This is presumably because the mass ratio R in the second layer was excessively high because the concentration of sodium sulfate in the mixed solution used for the hot water denaturation treatment was high.

  In Comparative Examples 11 and 12, the evaluation results of the corrosion resistance test, the adhesion test, and the post-processing adhesion test were “x”. This is presumably because the thickness of the first layer became insufficient because the temperature of the mixed solution used for the hot water denaturation treatment was low.

In Comparative Examples 13 and 14, the evaluation result of the corrosion resistance test was “x”. This is presumably because the hot water denaturation time was too long and the thickness of the second layer was excessively large.
In Comparative Examples 15 and 16, the evaluation result of the corrosion resistance test was “x”. This is presumably because the hot water denaturation time was too long and the first layer was excessively thick.

(5-5) Other effects exhibited by the aluminum alloy coated plate of each example In the aluminum alloy coated plate of each example, a hydrate film layer can be formed without necessarily using a substance that causes environmental pollution. Can do. That is, the aluminum alloy coated plate of each example can reduce the load on the environment.

  In the aluminum alloy coated plate of each example, a hydrate film layer can be formed without necessarily using a power source or the like. Therefore, the aluminum alloy coated plate of each Example can reduce manufacturing cost.

6). Other Embodiments Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment, and various modifications can be made.

  (1) A function of one component in each of the above embodiments may be shared by a plurality of components, or a function of a plurality of components may be exhibited by one component. Moreover, you may abbreviate | omit a part of structure of each said embodiment. In addition, at least a part of the configuration of each of the above embodiments may be added to or replaced with the configuration of the other above embodiments. In addition, all the aspects included in the technical idea specified from the wording described in the claims are embodiments of the present disclosure.

  (2) In addition to the above-described aluminum alloy coated plate, the present disclosure can be realized in various forms such as a product including the aluminum alloy coated plate as a constituent element and a method for forming a hydrate film layer.

DESCRIPTION OF SYMBOLS 1 ... Aluminum alloy coating board, 3 ... Aluminum alloy layer, 5 ... Coating film layer, 7 ... Hydrate film layer, 9 ... 1st layer, 11 ... 2nd layer

Claims (2)

An aluminum alloy layer;
A coating layer in contact with the aluminum alloy layer;
A hydrate film layer formed on the surface of the coating layer side of the aluminum alloy layer;
With
The hydrate film layer includes (a) a dense first layer mainly composed of aluminum, and (b) a porous layer that is located closer to the coating film layer than the first layer and contains magnesium and aluminum. With a second layer of quality,
The thicknesses of the first layer and the second layer are 500 to 1000 nm,
The aluminum alloy coating plate whose mass ratio of aluminum with respect to magnesium in the said 2nd layer is 0.6-1.4. It is a manufacturing method of the aluminum alloy coating plate according to claim 1,
Magnesium chloride having a concentration of 5.0 to 11.0 g / L, sodium bicarbonate having a concentration of 0.2 to 0.6 g / L, and sodium sulfate having a concentration of 1.0 to 5.0 g / L. The manufacturing method of the aluminum alloy coating plate which forms the said hydrate film | membrane layer by performing a hot water denaturation process to the said aluminum alloy layer using the mixed solution whose temperature is 75 degreeC or more.

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