JP4455192B2 - Thermoplastic resin coated aluminum plate - Google Patents

Description

The present invention relates to a thermoplastic resin-coated aluminum plate and a manufacturing method thereof, particularly, it relates corrosion resistance, the thermoplastic resin-coated aluminum sheet with excellent adhesion and environmental resistance of the resin layer.

  Aluminum materials are widely used as beverage cans, daily necessities, building materials, housings, and the like because they are lightweight and have excellent moldability and corrosion resistance. Many of these are subjected to surface treatment such as chromate treatment and resin coating for the purpose of improving corrosion resistance and slipperiness or decoration. As a resin coating method, conventionally, there is a method in which a coating obtained by dissolving or dispersing a resin in a solvent is applied to the surface of an aluminum material and baked to cure the resin layer. In recent years, from the viewpoint of environmental protection and production costs, a method of laminating a resin film on an aluminum material is being shifted.

  The aluminum material on which the resin film is laminated is subjected to molding processing such as bending processing, drawing processing, and ironing processing according to the application. In addition, when used as a food container, a corrosive liquid may come into contact with the aluminum material, and retort treatment may be performed for sterilization. As described above, since the aluminum material is exposed to various environments, the resin film is required to have adhesion and corrosion resistance that can withstand these treatments.

In order to improve the corrosion resistance of an aluminum material, various surface treatments have conventionally been applied to the aluminum material. Examples of the surface treatment include a chemical conversion treatment such as a phosphoric acid chromate treatment and a Zr-based treatment, an anodizing treatment such as sulfuric alumite, and a coating treatment for applying an inorganic paint or an organic paint.
Moreover, in order to improve the adhesiveness of an aluminum material and a resin film, it is necessary to improve the mechanical bond strength or chemical bond strength between both. As means for increasing the mechanical coupling force, for example, means utilizing the anchor effect can be considered.
JP-A-11-91034

  However, the above-mentioned phosphoric acid chromate treatment has a problem in terms of the environment because harmful Cr is used. In addition, since the chromate layer formed by the phosphoric acid chromate treatment does not have sufficient adhesion to the resin film, there is a problem that the resin film is peeled off in a harsh environment such as molding or retort treatment with a large amount of processing. is there. Moreover, there exists a problem that management of a process liquid is complicated in chemical conversion processes other than a phosphoric acid chromate process.

  Next, since the alumite sulfate formed by anodizing treatment has fine holes, an anchor effect using the holes is expected. However, since the fluidity of the resin constituting the resin film is low, there is a problem that the anchor effect cannot be obtained as expected because the resin cannot enter the hole. Moreover, in order to obtain an anchor effect, it is necessary to form a relatively large number of micropores. However, as the number of micropores increases, the barrier property against the aluminum material decreases and the corrosion resistance decreases due to the intrusion of corrosive substances. There is a problem that happens.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermoplastic resin-coated aluminum plate which is excellent in adhesion of a resin layer and excellent in corrosion resistance. Another object of the present invention is to provide a thermoplastic resin-coated aluminum plate that has excellent adhesion to a resin layer, excellent corrosion resistance, and low environmental burden.

In order to achieve the above object, the present invention employs the following configuration.
The thermoplastic resin-coated aluminum plate excellent in adhesion and corrosion resistance after retorting according to the present invention is formed on a substrate made of aluminum or an aluminum alloy and having at least one surface roughened, and the one surface roughened. An anodic oxide film having a thickness of 21 nm or more and 300 nm or less and a thermoplastic resin layer laminated on the anodic oxide film, and the arithmetic average roughness Ra of the anodic oxide film surface exceeds 0.1 μm. And a maximum height Rmax of more than 4 μm and 12 μm or less, and a surface area of 100 μm square is 20000 μm ² or more.

  According to the above configuration, the surface roughness of the anodic oxide film is set in the above range by forming the anodic oxide film on one surface of the substrate roughened in advance, so that the anodic oxide film and the thermoplastic resin layer A strong anchor effect can be expressed between the two and the adhesiveness of the thermoplastic resin layer can be enhanced.

Moreover, the thermoplastic resin-coated aluminum plate of the present invention is the thermoplastic resin-coated aluminum plate described above, and the silane coupling agent is 0.1 mg / m ² or more and 100 mg / m ² or less on the anodized film. It is characterized by being applied in a coating amount of

  According to the said structure, the adhesiveness of a thermoplastic resin layer can be improved more by apply | coating a silane coupling agent between an anodic oxide film and a thermoplastic resin layer.

  Moreover, it is preferable that a thermoplastic resin layer consists of a single layer or a multilayer resin film of two or more layers.

Next, according to the present invention , the arithmetic average roughness Ra of the anodic oxide film surface is in the range of 0.11 μm to 0.56 μm and the maximum height Rmax is in the range of 4.1 μm to 11.8 μm, The surface area of a 100 μm square is 24000 μm ² or more and 35000 μm ² or less, and relates to the thermoplastic resin-coated aluminum plate excellent in adhesion and corrosion resistance after retorting according to claim 1 or 2.

  According to the above configuration, the surface roughness of the anodic oxide film is set in the above range by forming the anodic oxide film on one surface of the substrate roughened in advance, so that the anodic oxide film and the thermoplastic resin layer A strong anchor effect can be expressed between the two and the adhesiveness of the thermoplastic resin layer can be enhanced. Further, since the anodizing treatment does not use a harmful treatment solution or the like, it is possible to reduce the burden on the environment.

The roughening treatment may be any of chemical etching, electrolytic etching, and mechanical roughening.
In addition, in the electrolytic treatment, it is preferable to use an electrolytic solution having low film solubility in order to prevent a previously roughened surface from being flattened by dissolution. The thickness of the anodic oxide film to be formed is desirably in the range of 21 nm to 300 nm.

According to the present invention, it comprises an anodized film having a thickness of 21 nm or more and 300 nm or less formed on a roughened surface, and a thermoplastic resin layer of a laminated film laminated on the anodized film, The arithmetic average roughness Ra of the anodic oxide film surface is in the range of more than 0.1 μm to 1 μm or less, the maximum height Rmax is in the range of more than 4 μm to 12 μm or less, and the surface area of 100 μm square is 20000 μm ² or more. Therefore, it is possible to provide a thermoplastic resin-coated aluminum plate having excellent adhesion after retorting of the thermoplastic resin layer of the laminated film and excellent corrosion resistance .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the thermoplastic resin-coated aluminum plate A of this embodiment includes a substrate 1 having at least one surface roughened, an anodized film 2 formed on the roughened surface 1a, A thermoplastic resin layer 3 laminated on the anodic oxide film 2 (hereinafter sometimes simply referred to as the resin layer 3) is generally configured. Further, the arithmetic average roughness Ra of the surface of the anodic oxide film 2 is in the range of more than 0.1 μm to 1 μm and the maximum height Rmax is in the range of more than 4 μm to 12 μm. Thus, the thermoplastic resin-coated aluminum plate A of the present embodiment has a strong anchor effect between the anodic oxide film 2 and the thermoplastic resin layer 3 because the surface of the anodic oxide film 2 is roughened. Is configured to be expressed.

The substrate 1 is made of aluminum or an aluminum alloy. The material of the substrate 1 is not particularly limited. For example, a pure aluminum-based 1000 series alloy, an Al—Cu series, an Al—Cu—Mg series 2000 series alloy, an Al—Mn series 3000 series alloy, Al-Si 4000 alloy, Al-Mg 5000 alloy, Al-Mg-Si 6000 alloy, Al-Zn-Mg-Cu alloy, Al-Zn-Mg 7000 alloy, Al -Fe-Mn-based 8000 series alloys are used, and casting alloys such as forming alloys, structural alloys, electrical alloys, and AC1A, AC2A, AC3A, and AC4B are used. The thickness of the substrate 1 is preferably in the range of 0.1 mm to 1 mm.
Also, those alloys subjected to various tempering treatments such as solution treatment and aging treatment can be used. Further, a clad material obtained by cladding these aluminum alloys on the surface can also be used. Moreover, the thing of the processed material which gave press molding processing etc. previously may be sufficient, and an unprocessed board | plate material, an extrusion material, and a cast may be sufficient.

  One surface 1a of the substrate 1 is subjected to roughening treatment in advance. By increasing the surface area of the surface 1a by the roughening treatment, the adhesion of the resin layer 3 can be improved.

  Next, as will be described later, the anodic oxide film 2 is formed by subjecting one surface 1a of the metal substrate 1 to electrolytic treatment, and has a thickness of 21 nm or more and 300 nm or less, and an arithmetic average roughness Ra of the surface 2a. The range is more than 0.1 μm and less than 1 μm and the maximum height Rmax is more than 4 μm and less than 12 μm. The surface roughness of the surface 2a is derived from the surface roughness of the first surface 1a roughened in advance. Although the surface of the surface 1a is slightly dissolved and flattened by the electrolytic treatment, since the electrolytic solution having relatively low solubility is used as will be described later, the dissolution of the surface is suppressed as much as possible, and the surface after roughening The surface roughness 1a is almost directly reflected in the surface roughness of the anodic oxide film 2. Since the roughened surface 1a is fragile, if the surface 1a is left as it is, the surface roughness of the surface 1a may decrease. Such a problem can also be prevented by forming a relatively hard anodic oxide film 2. In addition, the corrosion resistance of the substrate 2 can be improved by forming the anodic oxide film 2.

  The arithmetic average roughness Ra and the maximum height Rmax have a correlation with the surface area of the anodic oxide film 2, and the surface area of the anodic oxide film increases as Ra and Rmax increase. Thereby, the anchor effect with the thermoplastic resin layer 3 appears strongly, and the adhesiveness of the resin layer 3 improves. When the arithmetic average roughness Ra of the anodic oxide film 2 is 0.1 μm or less, the surface area of the anodic oxide film is reduced, the anchor effect is reduced, and the adhesiveness of the resin layer 3 is lowered. In addition, when the arithmetic average roughness Ra exceeds 1 μm, the resin layer 3 cannot follow the undulation of the surface of the anodic oxide film 2 and the adhesion between the anodic oxide film 2 and the resin layer 3 is deteriorated.

Further, if the maximum height Rmax is 4 μm or less, the surface area of the anodized film is reduced, the anchor effect is reduced, and the adhesiveness of the resin layer 3 under severe conditions such as a high temperature environment is lowered, which is not preferable. If the maximum height Rmax exceeds 12 μm, the resin layer 3 cannot follow the undulations on the surface of the anodic oxide film 2 and the adhesion between the anodic oxide film 2 and the resin layer 3 is lowered, which is not preferable.
The surface area of the anodic oxide film is preferably 20000 μm ² or more per 100 μm square. If it is less than 20000 μm ² , the adhesion area with the resin becomes insufficient, and sufficient adhesion cannot be obtained. The upper limit is practically 40000 μm ² .

  The thickness of the anodic oxide film 2 is preferably in the range of 21 nm to 300 nm. If the thickness is less than 21 nm, the film thickness tends to be non-uniform, and the adhesion to the substrate 1, adhesion durability and corrosion resistance are reduced. On the other hand, if the film thickness exceeds 300 nm, a crack is generated in the film itself when the metal substrate 1 is molded into a predetermined shape, and the adhesion durability and corrosion resistance to the metal substrate 1 are reduced. On the other hand, if the film thickness exceeds 300 nm, the surface of the anodic oxide film 2 is flattened and the adhesion of the resin layer 3 is lowered, which is not preferable. A particularly desirable film thickness of the anodic oxide film 2 is in the range of 40 nm to 200 nm.

  The porosity of the anodic oxide film 2 is not particularly limited. That is, the anodic oxide film 2 in the present invention may be either nonporous or porous. In practice, however, a relatively non-porous anodic oxide film 2 is easily obtained because an electrolyte having low solubility is used to reflect the surface roughness of the surface 1a on the surface roughness of the anodic oxide film 2. There is a tendency. In addition, the nonporous anodic oxide film 2 can reduce the porosity, prevent the entry of corrosive substances, and improve the corrosion resistance of the substrate 1. From the above viewpoint, the porosity of the anodic oxide film 2 is preferably in the range of 20% or less.

  Further, although the anodic oxide film 2 may contain moisture during the electrolytic treatment, the water content in the anodic oxide film 2 is preferably 25% or less. If the water content exceeds 25%, the amount of moisture contained in the anodic oxide film 2 is increased by the heat received by the aluminum plate A, and this may lead to a significant decrease in the adhesiveness of the resin layer 3, which is preferable. Absent. A more preferable moisture content range is 15% or less.

Next, as the thermoplastic resin layer 3, an organic resin film or an organic resin film made of a polyester resin, a polyamide resin, a copolymer polyester resin, an epoxy resin, a polyolefin resin, a fluorine resin, or the like can be used. The thermoplastic resin layer 3 is not limited to a single layer, and may be a laminated film of two or more layers. What is necessary is just to change the material of the thermoplastic resin layer 3 suitably according to the use of the aluminum plate A. FIG. For example, when the aluminum plate A is used for a food container, a polyester resin is preferable from the viewpoint of barrier properties and flavor properties.
Moreover, as the resin layer 3, the resin film which biaxially stretched said resin is preferable from a viewpoint of handling property. Furthermore, the resin film can be selected from either a single layer or a multilayer of two or more layers, but a two-layer film having a layer having a low melting point on the side in contact with the aluminum surface is preferable because adhesion can be secured at a lower temperature.
In addition, although the film thickness of the thermoplastic resin layer 3 is based also on the use of the aluminum plate A, the range of 6 micrometers or more and 50 micrometers or less is preferable from a viewpoint of corrosion resistance, a moldability, and production cost.

If necessary, a silane coupling agent may be applied between the anodic oxide film 2 and the thermoplastic resin layer 3. The silane coupling agent generates a chemical bond between the anodic oxide film 2 and the thermoplastic resin layer 3 and further improves the adhesion of the thermoplastic resin layer 3. As the silane coupling agent, amino, epoxy, vinyl, methacrylic, mercapto and the like are preferable.
The coating amount of the silane coupling agent to the anodic oxide film 2 is preferably 0.1 mg / ^{m 2} or more 100 mg / ^{m 2} or less. If the coating amount is less than 0.1 mg / m ² , the coating unevenness of the silane coupling agent is likely to occur, which is not preferable. If the coating amount exceeds 100 mg / m ² , peeling of the silane coupling agent in the layer is likely to occur. This is not preferable because the adhesion of the resin layer 3 is lowered. A more preferable range of the coating amount is 1.0 mg / m ² or more and 50 mg / m ² or less.

Next, the manufacturing method of the thermoplastic resin-coated aluminum plate A of this embodiment will be described.
First, the substrate 1 made of the above aluminum or aluminum alloy is prepared. The substrate 1 is preferably pre-treated in advance. The means for this pretreatment is not particularly limited as long as it can remove the oil and fat adhering to the one surface 1a of the substrate 1 and remove the heterogeneous oxide film on the surface of the material. For example, after performing a degreasing treatment with a weak alkaline degreasing solution, a method of performing a desmut treatment in an aqueous nitric acid solution or a method of performing an acid cleaning after the degreasing treatment is appropriately selected and used.

  Next, the surface 1a of the substrate 1 is roughened. As a specific method for the roughening treatment, a chemical etching method, an electrolytic etching method, a mechanical roughening method, or the like can be used. In the chemical etching method, for example, the surface 1a of the substrate is immersed in an aqueous solution such as hydrochloric acid, sulfuric acid, caustic soda, and the aluminum surface is chemically dissolved to roughen the surface. Further, in the electrolytic etching method, for example, the surface is roughened by applying an electric current to the aluminum plate and electrochemically dissolving the aluminum surface in a solution containing chlorine ions or an aqueous solution such as hydrochloric acid and nitric acid. The power source at this time may be either direct current or alternating current. Furthermore, examples of the mechanical surface roughening method include a method of roughening a rolling roll and a shot blasting method. In particular, the electrolytic etching method is most preferable because a uniform and fine roughening treatment is possible and control of the treatment is easy as compared with the chemical etching method and the mechanical roughening method.

  Next, the anodized film 2 is formed by subjecting the roughened surface 1a to electrolytic treatment in an electrolytic bath. The electrolytic bath is preferably an aqueous solution in which the generated anodic oxide film is difficult to dissolve, such as boric acid, borate, carbonate, tartrate, silicate, citrate, malonate, adipate, etc. An aqueous solution in which one or more selected from is dissolved is used. Of these electrolytes, boric acid, adipate, and phthalate are preferable from the viewpoints of properties of the oxide film, cost, and the like. The electrolyte concentration in the electrolytic bath is selected in the range of 1% by mass to the saturated concentration of the electrolyte. For example, in the case of boric acid, the range of 1% to 20% is preferable. If the electrolyte concentration is too high, the film solubility may increase and a porous film may be formed, and the anion content and water content may also increase. The bath temperature of the electrolytic bath is sufficient in the range of 40 to 60 ° C., and the bath temperature does not need to be as high as 60 ° C. or higher. The pH of the electrolytic bath is preferably in the range of 4 to 10. If the pH is too high, it is not preferable because it tends to be porous. In addition, when an electrolyte having a high film solubility such as sulfuric acid, oxalic acid, phosphoric acid or the like is used, pores having a diameter of about 10 nm to 30 nm are generated, and a thermoplastic resin having low fluidity cannot enter the pores. As a result, the adhesion area of the resin layer 3 is reduced, leading to a decrease in adhesion. Furthermore, since the roughened surface 1a is chemically dissolved and smoothed, it is not preferable.

In this electrolytic bath, the substrate 1 is electrolyzed by being connected to a power source so as to be an anode even if it is continuous or intermittent. An insoluble conductive material is used for the cathode. As the electrolytic current, a direct current is used. In direct current electrolysis, electrolysis is performed with a direct current density of about 0.3 to 10 A / dm ² and an electrolysis time of about several seconds to 20 seconds. If the current density is low, electrolysis for a long time is required, resulting in an increase in cost, and the film is more likely to be dissolved, so that there is a possibility of becoming porous. The applied voltage is in the range of about 15 to 210 V, preferably about 3 to 150 V, because there is a relationship that the thickness of the oxide film formed with respect to the voltage of 1 V is about 14 mm in direct current. By this electrolysis, a uniform anodic oxide film 2 having a thickness of 20 to 300 nm, preferably 40 to 200 nm, is formed on one surface 1a of the substrate 1.

  The anodic oxide film 2 thus obtained is almost nonporous, and its porosity is 20% or less at the maximum. Further, the water content of the anodized film shows a value of 25 wt% or less. The surface roughness of the anodic oxide film 2 is in the range where the arithmetic average roughness Ra exceeds 0.1 μm and is 1 μm or less, and the maximum height Rmax is in the range exceeding 4 μm and 12 μm or less.

  The above anodic oxidation treatment can be performed on unprocessed aluminum or aluminum alloy, and can also be performed on a state after a forming process such as a press process.

Next, a thermoplastic resin layer 3 is laminated on the formed anodic oxide film 2. Lamination of the thermoplastic resin layer 3 is performed, for example, by heating the substrate 1 after the formation of the anodized film to a predetermined temperature and then pressing the thermoplastic resin film with a pressure roll. Furthermore, it is preferable to heat-treat the thermoplastic resin layer 3 after the pressure bonding. By this heat treatment, the thermoplastic resin layer 3 can be temporarily softened and fixed on the surface of the anodized film, and the adhesion of the resin layer 3 can be further improved. The heat treatment temperature is preferably in the temperature range where the resin layer is moderately softened, and specifically in the range of 180 ° C to 260 ° C. If the heat treatment temperature is less than 180 ° C., the resin layer 3 is not sufficiently fixed and the adhesion of the resin layer 3 is lowered, which is not preferable. Further, if the heat treatment temperature exceeds 260 ° C., the resin layer 3 is melted, which is not preferable. The heat treatment time is preferably in the range of several seconds to 10 minutes.
In this way, a thermoplastic resin-coated aluminum plate A composed of the substrate 1, the anodic oxide film 2, and the resin layer 3 is obtained.

  A silane coupling agent may be applied on the anodic oxide film 2 before the heat resistant coating film 3 is formed. The silane coupling agent is applied by preparing a paint obtained by diluting the silane coupling agent with an appropriate solvent, and applying this paint to the anodic oxide film 2 using a bar coater or the like. After coating with a bar coater or the like, the silane coupling agent is applied by removing the solvent by heating or the like. The coating amount of the silane coupling agent may be adjusted by the dilution concentration of the coating material and the coating amount of the coating material by a bar coater or the like. In addition, as a coating method, a spray method, a roll coating method, or the like may be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
First, a JIS 5052 aluminum alloy plate rolled to 0.3 mm was prepared as a metal substrate. Next, a roughening treatment was performed on one surface of the plate material. For the roughening treatment, three methods of chemical etching, electrolytic etching, and mechanical roughening treatment were used. Chemical etching was performed by immersing the plate material in a caustic soda solution for a predetermined time. The electrolytic etching was performed by flowing an alternating current in an aqueous nitric acid solution. Further, in mechanical surface roughening, it was processed by alumina shot blasting.
Next, in a borate aqueous solution having a pH of 7, a liquid temperature of 50 ° C. and a concentration of 5% or in a 5% silicate aqueous solution, the above plate material is used as an anode, carbon is used as an anode, and electrolytic treatment is performed at 1.5 A / dm ^2. And an anodic oxide film was formed. The thickness of the anodic oxide film was adjusted by voltage, and the electrolysis time was 5 seconds.

Next, a two-layer polyester film and a single-layer polyester film were prepared as the thermoplastic resin layer. The bilayer polyester film is a biaxially stretched film obtained by copolymerizing ethylene terephthalate and isophthalate, and has an adhesive layer (melting point 230 ° C.) in contact with the anodized film and an alignment layer on the side not in contact with the anodized film. It has a two-layer structure (melting point 260 ° C.). The film thickness is 11 μm for the alignment layer and 1 μm for the adhesive layer. The single-layer polyester film is a biaxially stretched film having a melting point of 250 ° C. and a film thickness of 10 μm.
Lamination of the thermoplastic resin layer was performed by heating the plate material after the formation of the anodized film to 120 ° C. with a heat roll and then pressing the resin film with a pressure roll at a linear pressure of 18 kg / cm ² . Next, the laminated plate was heated at 200 ° C. to 250 ° C. for 5 seconds with a high-frequency induction heating device, so that the film was softened and fixed to the anodic oxide film. In this way, thermoplastic resin-coated aluminum plates of Examples and Comparative Examples were produced.

  For some samples, a silane coupling agent was applied on the anodized film before the thermoplastic resin layer was laminated. Specifically, by preparing a 0.1-5% aqueous solution of an amino-based silane coupling agent, applying this aqueous solution on the anodized film by a roll coating method, and performing a heat treatment at 100 ° C. for 1 minute, A silane coupling agent was applied.

Table 1 shows details of the roughening conditions and electrolytic treatment conditions performed on the examples, test examples, and comparative examples. Table 2 shows the evaluation results of the surface roughness, surface area and film thickness of the anodized film, the coating amount of the silane coupling agent, adhesion and corrosion resistance.
For Test Example 11 in Table 2, a single-layer polyester film was used as the thermoplastic resin layer. A laminated polyester film was used except for Test Example 11. In Comparative Example 6, the electrolytic treatment was omitted, and a chromate treatment was performed instead. The adhesion amount of Cr was 15 mg / m ² .

In addition, the arithmetic average roughness Ra and the maximum height Rmax in Table 2 were measured in accordance with a method defined in JIS standard (B0601-1994).
The film thickness in Table 2 was obtained by cutting the anodized film with a microtome and observing the cross section.
The surface area of the anodic oxide film was determined by measuring the surface area of any 10 locations with a laser microscope (KEYENCE VK-8500) with a field of view of 500 times.

In addition, evaluation of adhesion (70 ° C. hot water) is carried out by performing a DuPont impact test in which a 1/4 inch steel ball is dropped from a height of 50 cm on an aluminum plate to make the resin layer side convex, After being immersed in warm water for 30 minutes, the degree of peeling of the resin layer when the adhesive tape was peeled off after being applied to the resin layer was evaluated. The case where the resin layer was not peeled was indicated as “◯”, the case where a part was peeled as “Δ”, and the case where the tape was almost peeled off as “X”.
Furthermore, the adhesiveness (retort treatment) was evaluated by performing a DuPont impact test in the same manner as described above to make the resin layer convex, performing a retort treatment at 125 ° C. for 30 minutes, and then applying an adhesive tape to the resin layer. It evaluated by the grade of peeling of the resin layer when it peeled off after sticking. The case where the resin layer was not peeled was indicated as “◯”, the case where a part was peeled as “Δ”, and the case where the tape was almost peeled off as “X”.

  In addition, the corrosion resistance is the same as described above, the DuPont impact test is carried out, the aluminum plate after the test is immersed in 5% saline solution at 50 ° C. for 7 days, and then the corrosion state of the impact test portion is observed. It was evaluated by doing. The case where there was no change in the appearance of the resin layer was indicated as ◯, the case where a part was corroded was indicated as Δ, and the case where the entire surface was corroded was indicated as ×.

As shown in Table 2, the aluminum plates of Examples 1 to 12 had better results than the comparative examples in both adhesion and corrosion resistance.
On the other hand, in Comparative Example 1, since the surface roughness of the anodic oxide film was small, particularly the adhesion after the retort treatment was remarkably lowered, and the corrosion resistance was also lowered.
In Comparative Example 2, since the maximum height Rmax of the anodic oxide film was too high, the resin layer could not follow the surface shape of the anodic oxide film, and the adhesion after retorting was significantly reduced.
In Comparative Example 3, since the thickness of the anodic oxide film was too thick, cracks occurred in the anodic oxide film, so that the salt solution entered the anodic oxide film, and the corrosion resistance was lowered. In addition, the adhesiveness of the resin layer was favorable.
In Comparative Example 4, since the anodic oxide film was too thin, the anodic oxide film became non-uniform, and salt solution entered from the thin part of the anodic oxide film, resulting in a decrease in corrosion resistance. In addition, the adhesiveness of the resin layer was favorable.

About Comparative Example 5, since the coating amount of the silane coupling agent was excessive with respect to Example 9, the adhesiveness with respect to Example 9 was slightly lowered.
In Comparative Example 6, since the chromate film was formed instead of the anodic oxide film, the adhesion after the retort treatment was greatly reduced.
In Comparative Example 7, since the surface area of the anodic oxide film was small, the adhesion after the retort treatment was greatly reduced.

  The thermoplastic resin-coated aluminum plate of the present invention is suitably used for building materials, housings for various electronic devices, beverage cans / food cans, and the like.

The cross-sectional schematic diagram of the thermoplastic resin coating | cover aluminum plate which is embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Anodized film, 3 ... Thermoplastic resin layer, A ... Thermoplastic resin coating aluminum plate

Claims (3)

A substrate made of aluminum or an aluminum alloy and having at least one surface roughened; an anodized film having a thickness in the range of 21 nm to 300 nm; and an anodized film formed on the roughened surface; It comprises a thermoplastic resin layer of laminated laminated films, and the arithmetic average roughness Ra of the anodized film surface is in the range of more than 0.1 μm to 1 μm and the maximum height Rmax is more than 4 μm to 12 μm or less. A thermoplastic resin-coated aluminum plate excellent in adhesion and corrosion resistance after retorting , characterized in that the surface area of a 100 μm square is 20000 μm ² or more. ^{2. The} adhesion and corrosion resistance after retorting according to claim 1, wherein a silane coupling agent is applied on the anodic oxide film at a coating amount of 0.1 mg / m ² or more and 100 mg / m ² or less. Excellent thermoplastic resin coated aluminum plate. The arithmetic average roughness Ra of the surface of the anodic oxide film is in the range of 0.11 μm to 0.56 μm, the maximum height Rmax is in the range of 4.1 μm to 11.8 μm, and the surface area of 100 μm square is 24000 μm. ² Above, 35000μm ² The thermoplastic resin-coated aluminum plate having excellent adhesion and corrosion resistance after retorting according to claim 1 or 2, wherein:

Images