JP2008127625A - Aluminum plate for forming cap having excellent resin adhesiveness after forming, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the coating film adhesiveness after forming a coating film containing pigment on an aluminum-made cap which is subjected to a very stringent forming and for which retort-resistance is required. <P>SOLUTION: A polymer of an acrylic acid compound containing one or more carboxylic groups for each weight average molecular weight 1,000 is deposited with the deposit of ≥5 mg/m<SP>2</SP>and ≤5,000 mg/m<SP>2</SP>on an oxide film mainly consisting of Al and O in which the thickness is ≤200 nm; C content of the surface is ≤50 mg/m<SP>2</SP>, and the maximum concentration in the depth direction from the uppermost surface to an interface between the oxide film and aluminum is Mg:≤5 mass%, and H:≤10 mass%. In addition, a coating film containing pigment of ≥5 mass% to the dry weight is deposited on a base material in which a polymer of an acrylic acid compound containing one or more carboxylic groups for each weight average molecular weight 500 with the weight average molecular weight being ≥1,000 and ≤1,000,000 with the deposit of ≥5 mg/m<SP>2</SP>and ≤5,000 mg/m<SP>2</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum plate coated with a resin paint containing a pigment on at least one side, and more particularly to an aluminum plate for cap molding having excellent resin adhesion after molding such as press molding.

  Aluminum plates or aluminum alloy plates (hereinafter referred to as “aluminum plates”) are lightweight, have appropriate mechanical characteristics, and have excellent aesthetics, moldability, corrosion resistance, etc. Widely used in products, structural materials, machine parts, etc.

  In order to further improve the corrosion resistance and elution resistance, to improve the appearance, to prevent scratches, and the like, the aluminum plate for the above uses is often subjected to coating with a resin paint and laminating of a resin film. At this time, in order to improve the resin adhesion and the corrosion resistance, the aluminum plate is subjected to a base treatment based on existing technology (for example, a chemical-molding base treatment such as phosphate chromate, chromate chromate and zirconium phosphate). It is common. In the case of an aluminum cap, a so-called pre-coating material is often used in which a base treatment and a resin coating are applied to an aluminum plate of the material and then molded.

  Cap-coated pre-coated aluminum alloy sheets require resin adhesion that prevents the resin from peeling even after molding, corrosion resistance that is not affected by corrosive atmospheres, and workability that can withstand advanced molding . In response to such demands, various proposals have been made in a wide range of fields, particularly from the standpoint of improving coating film adhesion. In particular, in the ground treatment method, in addition to chemical molding ground treatment based on the prior art, a method is proposed in which an organic material for improving adhesion is provided thereon, and then a resin is provided thereon. For example, in Patent Document 1, after an aluminum plate is subjected to phosphoric acid chromate treatment, the aluminum plate is treated in a solution containing a specific phenol polymer, or the aluminum plate is subjected to phosphoric acid chromate treatment and then subjected to silane treatment. A method has been proposed in which a treated aluminum plate is prepared and coated with a thermoplastic resin to form a resin-coated aluminum plate, which is then drawn and ironed to form a capacitor exterior container. Patent Document 2 discloses that in an aluminum can material, at least the surface of the aluminum substrate on the inner surface of the container is a surface treatment layer mainly composed of an inorganic substance, an organic surface treatment layer mainly composed of an aqueous phenol resin, and further thereon. An aluminum can material characterized by having a multilayer structure of a polyester resin coating layer is provided.

In recent years, the need for reduction and reduction of heavy metal compounds in products and manufacturing processes has been screamed due to increasing environmental awareness. From such a point of view, a method for imparting coating film adhesion to the aluminum oxide film itself has been proposed without carrying out chemical forming ground treatment on the aluminum plate surface. For example, in Patent Document 3, on the aluminum plate surface, the thickness is 1 to 200 nm, and the maximum concentration in the depth direction from the outermost surface to the oxide film / aluminum interface is 5 mass% or less for Mg, 10 mass% or less for H, And the aluminum material for can lids which provides the oxide film which has Al and O as a main component whose C amount of the outermost surface is 50 mass% or less, and coats a resin film on it is proposed.
JP 2001-303273 A JP 2001-121648 A Japanese Patent No. 3850253

However, the conventional techniques as described above have the following problems.
In other words, aluminum caps used in re-sealable containers such as bottle cans are capacitor cases that are the subject of Patent Document 1 such as deep drawing molding, screw molding, and perforation processing with pilfer proofing. And compared with the aluminum can which is the object of Patent Documents 2 and 3, it undergoes very severe processing. In addition, pigments are often added to the resin coating film due to the appearance and design requirements, which is disadvantageous for coating film adhesion. Further, in recent years, since bottle cans have been adopted for hot beverages, retort resistance has also been required for the resin coating film of caps.
Under such conditions, the techniques such as Patent Documents 1, 2, and 3 have problems such as peeling of the coating film after retorting because the resin adhesion after being subjected to severe processing is insufficient.

As a result of repeated studies to solve the above problems, the present inventor has reduced the burden on the global environment, and in order to improve the coating film adhesion after processing in paints containing pigments and dyes, On the surface of the aluminum oxide film having a specific composition, a polymer of an acrylic acid compound containing one or more carboxyl groups per polymerization unit is applied in an amount of 5 mg / m ² or more and 5000 mg / m ² or less. It has been found that it is extremely effective to provide it.

That is, in the first aspect of the invention, in the base treatment of the cap-molding aluminum plate provided with a coating containing 5 mass% or more of pigment with respect to the dry weight, the thickness is 200 nm or less and the surface C amount is 50 mg / m ² or less The maximum concentration in the depth direction from the outermost surface to the oxide film / aluminum interface is Mg: 5 mass% or less, and H: 10 mass% or less. For cap molding with excellent resin adhesion after molding processing, characterized in that a polymer of an acrylic acid compound containing at least one carboxyl group is provided in an adhesion amount of 5 mg / m ^{2 to} 5000 mg / m ² It is an aluminum plate.

The invention of claim 2 is an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH of 8 or more and less than 12 at 25 ° C. with respect to the aluminum alloy sheet after cold rolling. 1 or more per 1000 weight average molecular weight after performing final degreasing with water having a total carbon content of 0.5 mass% or less without touching water exceeding 95 ° C. in the middle of the process after performing alkaline degreasing to m ² or more. The aqueous or solvent-based polymer solution of an acrylic acid compound containing a carboxyl group is applied and dried in an atmosphere of 30 ° C. to 300 ° C. for 1 second to 600 seconds. It is a manufacturing method of the aluminum plate for cap shaping | molding excellent in the resin adhesiveness after the shaping | molding process of this.

Further, the invention of claim 3 is an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH of 8 or more at 25 ° C. with respect to the aluminum alloy sheet after cold rolling, and the etching amount is 10 mg / m ^2. Perform alkaline degreasing as described above, perform acid cleaning with an acid having a bath temperature of 95 ° C. or lower, a pH at 25 ° C. of 4.0 or lower, and an Al ion concentration and an Mg ion concentration of 1 mass% or less, respectively. Water or solvent-based acrylic acid containing at least one carboxyl group per weight average molecular weight of 1000 after final washing with water having a total carbon content of 0.5 mass% or less without being exposed to water exceeding 95 ° C. 2. The molded tree according to claim 1, wherein a polymer solution of the compound is applied and dried in an atmosphere of 30 ° C. to 300 ° C. for 1 second to 600 seconds. This is a method for producing an aluminum plate for cap molding excellent in oil adhesion.

  The cap-molding aluminum plate made according to the present invention has high adhesion to the coating film containing the pigment and dye and excellent molding processability.

Hereinafter, details of the present invention will be described in order.
The present invention is roughly composed of two elements. That is, “an aluminum oxide film having excellent coating film adhesion” and “providing an acrylic resin between the oxide film and the coating film”.

First, an aluminum oxide film having excellent coating film adhesion will be described.
In order to satisfy mechanical strength and workability, an aluminum alloy (JIS-5021, 5052, 5151, 5182, etc.) to which Mg of about 2 to 5 mass% is added is used for the cap molding aluminum material. These materials are known to segregate and concentrate Mg in the aluminum matrix on the surface during heating and rolling. The inventors investigated in detail the element distribution in the depth direction of the oxide film, so-called depth profile, using an analytical instrument such as GDS (glow discharge emission spectroscopy) or AES (Auger electron spectrum). As a result, it was confirmed that each element does not exist uniformly in the entire oxide film and does not form a clear two-layer, and the concentration distribution of each element is different. The elements to be measured are H, C, O, Mg, Al, Mn, Si, Fe, Zn, Cr, and Zr. Hereinafter, the mass% of each element will be discussed based on the 11 elements as a population. However, these are considered to cover almost all the surface of the aluminum material, so that the generality of the discussion is not impaired. Further, the measurement accuracy in the depth direction is sufficiently guaranteed to be 1 nm.

  Mg was not uniformly present in the entire oxide film, and the portion slightly deeper than the outermost surface was distributed with the most concentrated concentration gradient. At this time, the oxide film prepared so that the maximum concentration of Mg in the depth direction from the outermost surface to the oxide film / aluminum interface is 5 mass% or less is the coating film adhesion between the cap coating resin and the aluminum material, It was found that the coating film adhesion after the strong processing accompanied by the reduction of the plate thickness is sufficiently high, whereas the coating film adhesion after the processing is remarkably lowered when the maximum concentration exceeds 5 mass%. This is presumably because the Mg compound has poor affinity with pure aluminum oxide, and the coating film is easily peeled off from the Mg compound / aluminum oxide interface. Moreover, since the Mg compound has high solubility in water, if it is present in a large amount, the corrosion resistance is also lowered. These adverse effects are prominent when the maximum Mg concentration in the depth direction exceeds 5 mass%.

  Moreover, H (hydrogen) mainly derived from hydroxide also has an inclined structure in the depth direction, similar to Mg. And when the maximum concentration in the depth direction from the outermost surface to the oxide film / aluminum interface is adjusted to 10 mass% or less, the coating film of the paint and the coating film after processing of the aluminum material are sufficiently high. On the other hand, when the maximum density exceeded 10 mass%, it discovered that the coating-film adhesiveness after a process fell. The reason for this is that compounds containing H (Al hydroxide, Mg hydroxide, etc.) are fragile, so when strong processing such as drawing, screw processing and perforation processing in cap molding is performed, the compound containing H is the starting point. This is probably because the oxide film is destroyed. The adverse effect is prominent when the maximum concentration of H exceeds 10 mass%.

Furthermore, C (carbon) mainly derived from organic substances attached to the surface of the oxide film needs to be regulated together with Mg and H. When the adhesion amount of C exceeds 50 mg / m < ² >, the wettability of the acrylic resin mentioned later is inhibited and coating defects such as pinholes are induced. In addition, since the adhesive force between the oxide film and the acrylic resin layer is reduced, a region having low adhesion is formed as a result.

  In addition, since the effect of said Mg, H, and C is all large, the maximum density | concentration should be prescribed | regulated simultaneously, and sufficient coating-film adhesiveness cannot be exhibited only by specifying only one element.

  Further, the thickness of the oxide film must be 200 nm or less. This is because when severe processing such as cap molding is performed, a strong stress is applied to the oxide film, so that a thick oxide film exceeding 200 nm causes cohesive failure and extremely deteriorates the adhesion of the coating film.

Next, the effect of providing an acrylic resin on the aluminum oxide film will be described.
The inventor performed cross-sectional observation of the coated plate with a TEM (transmission electron microscope) and examined the interface between the aluminum plate and the coating film. As a result, the coating film containing 5 mass% or more of pigment on the dry weight was formed on the aluminum plate surface. When applied directly, it was confirmed that the pigment particles were in direct contact with the plate surface. In many cases, the pigment in the cap paint refers to titanium oxide particles and silica particles. Since these substances have almost no interaction with the aluminum oxide film, they do not contribute to the adhesion of the coating film at all. In addition, since the contact area between the oxide film and the coating film resin component is intercepted, it acts rather in the direction of decreasing the coating film adhesion. As a means for maximizing the limited contact area, a polymer of an acrylic acid compound containing at least one carboxyl group per 1000 weight average molecular weight (hereinafter referred to as an acrylic resin) between the oxide film and the coating film. ), The resin component of the coating film and the acrylic resin are entangled by thermal vibration or the like to form a kind of melt-bonded layer, and as a result, the contact area between the oxide film and the coating film resin component increases. For the above reasons, it was discovered that the adhesion was improved, and the present invention was achieved.

  In the present invention, an acrylic resin containing one or more carboxyl groups per weight average molecular weight of 1000 is most suitable as a material provided between the oxide film and the coating film. This is because the carboxyl group contained in the acrylic resin is strongly bonded to the Al-O portion of the aluminum oxide film, and the resin skeleton exhibits the effect of forming a molten adhesive layer with the resin component of the coating film. This is because it acts strongly on both the coating film and the coating film. In addition, acrylic resins generally have high refractive index and are colorless and do not contain bisphenol A, which is pointed out to be an endocrine disrupting substance (so-called environmental hormone). It has. For the present invention, a known acrylic resin that satisfies the requirements for the carboxyl group content can be applied as it is. Specifically, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid, polymethacrylic acid ester, polyhydroxyacrylic acid, polyhydroxyacrylic acid ester and copolymers thereof are suitable. In addition, resins whose pH is adjusted with ammonia, amines, alkali metal hydroxides, or the like can also be suitably used. Furthermore, a resin in which a melamine compound and a urea compound are added as a cross-linking agent can also be suitably used. The molecular weights of these resins are particularly preferably those having a weight average molecular weight of 1,000 or more and 1,000,000 or less. This is because when the weight average molecular weight is less than 1,000, the water solubility of the resin itself is increased, and there is a concern about the elution of the acrylic resin layer in the retort treatment or the like. This is because uneven coating due to the increase tends to occur.

In the present invention, it is essential that the amount of the acrylic resin is 5 mg / m ² or more and 5000 mg / m ² or less. This is because if the amount of the acrylic resin is less than 5 mg / m ² , the effect of increasing the contact area due to the thermal vibration described above is insufficient, and the coating film adhesion cannot be ensured. Moreover, when it exceeds 5000 mg / m < ² >, the residual stress of an acrylic resin layer will become large and will cause the cohesive failure of an acrylic resin layer when a strong process is performed.

  The cap-molding aluminum plate thus obtained exhibits processing adhesion with a coating film containing 5 mass% or more of pigment with respect to the dry weight. In this case, the pigment is, in many cases, titanium oxide particles and / or silica particles, and in order to exhibit the color forming effect and the background color concealing effect, it is almost essential to have a blending amount of 5 mass% or more. is there. In addition, as a resin constituting the main body of the coating film, resins generally used for paints such as polyester resins, epoxy resins and vinyl chloride resins can be used as they are. The paint containing the pigment may be water-soluble or solvent-based. Furthermore, since the present invention improves the processing adhesion between the coating film containing the pigment and aluminum, various ink layers may be provided on the coating film containing the pigment for the purpose of imparting color, and as a top coat. Various finishing clear coatings may be provided.

By the way, in order to obtain the oxide film referred to in claim 1, as an example, the etching amount is 10 mg in an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH at 25 ° C. of 8 or more and less than 12. The method of performing alkaline degreasing of / m ² or more can be mentioned. Conventionally, Mg concentrated on the surface of an aluminum plate has not been removed by alkaline etching, but the bath temperature is 30 ° C. or more and 95 ° C. or less, the pH at 25 ° C. is 8 or more and less than 12, and the etching amount is 10 mg / m 2. Only when it was ² or more, it was found that the surface Mg was removed and the formation of hydroxide was suppressed. When the alkaline bath temperature is lower than 30 ° C, the etching rate is lowered, which adversely affects the productivity. When the alkaline bath temperature is higher than 95 ° C, boehmite-like hydroxide is rapidly formed by high-temperature moisture, and the thickness of the oxide film Are also likely to increase. When the pH of the solution at 25 ° C. is less than 8, the etching of aluminum does not proceed. When the pH is 12 or more, not only the surface Mg is reduced but also concentrated. When the etching amount is less than 10 mg / m ² , Mg on the surface is not sufficiently removed, and a uniform oxide film is hardly formed. In addition, if the etching amount is large, there is no effect on the performance of the oxide film, but if it exceeds 200 mg / m ² , the accuracy of the aluminum plate thickness will be adversely affected, and sludge may increase to impair the surface quality. , 200 mg / m ² or less is more preferable.

In addition to the above method, alkaline degreasing is performed so that the etching amount becomes 10 mg / m ² or more with an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH at 25 ° C. of 8 or more, and then the bath temperature. Alternatively, a method of performing acid cleaning with an acid having a pH of 95 ° C. or lower, a pH at 25 ° C. of 4.0 or lower, and an Al ion concentration and an Mg ion concentration of 1 mass% or less may be used. When the alkaline bath temperature is lower than 30 ° C, the etching rate is lowered, which adversely affects the productivity. When the alkaline bath temperature is higher than 95 ° C, boehmite-like hydroxide is rapidly formed by high-temperature moisture, and the thickness of the oxide film Are also likely to increase. When the etching amount by alkali degreasing is 10 mg / m ² , Mg on the surface is not sufficiently removed, and a uniform oxide film is not formed. If the amount of etching is large, there is no effect on the performance of the oxide film, but if it exceeds 200 mg / m ² , the accuracy of the aluminum plate thickness will be adversely affected, and the surface quality may be impaired due to increased sludge. / M ² or less is more preferable. In addition, it is known that acid cleaning contributes to the reduction of Mg. However, when the temperature exceeds 95 ° C., boehmite-like hydroxide is rapidly formed by high-temperature moisture, and the oxide film thickness tends to increase. Although there is no particular limitation on the lower limit of the bath temperature, practically it is preferably 30 ° C. or higher, and more preferably around 50 ° C. Moreover, when pH exceeds 4.0, the removal effect of surface Mg will be halved. Further, in defining the Mg and H concentrations in the oxide film, which is a feature of the present invention, if Al ion concentration in the pickling bath exceeds 1 mass%, Al hydroxide and the like remain on the surface, so that H and Mg ion concentration are 1 mass. If it exceeds 50%, an Mg compound is deposited on the surface, so Mg is concentrated in the oxide film.

  And in the water washing process performed after alkali degreasing and after alkali degreasing and pickling, you must not touch water exceeding 95 degreeC. This is because boehmite-like hydroxide is rapidly formed by contact with water exceeding 95 ° C., and the oxide film thickness tends to increase. Further, in the final stage of water washing, water having a total carbon content of 0.5 mass% or less must be used. This is because when the final cleaning is performed with water having a carbon content of more than 0.5 mass%, C remains on the surface of the aluminum oxide film, which hinders the adhesion of the carboxyl group-containing acrylic resin.

A cap-molding aluminum plate according to claim 1 can be obtained by applying an aqueous or solvent-based carboxyl group-containing acrylic resin solution prepared at an appropriate concentration to the aluminum surface thus obtained and drying it. it can. At this time, if the drying temperature is lower than 30 ° C, the volatilization rate of water or solvent is slow, which adversely affects the productivity. If the drying temperature exceeds 300 ° C, energy for maintaining the temperature is wasted. In particular, when a water-soluble acrylic resin is used, an oxide film may grow, which is not preferable. When the drying time is less than 1 second, the water or solvent is not sufficiently volatilized, and when it exceeds 600 seconds, the productivity is adversely affected. In addition, there is no restriction | limiting in particular about the application | coating method of an acrylic resin solution, The method of squeezing with a roll after immersing a board in a solution, the method of apply | coating to a board with a coater roll, the method of spraying on a board with a spray, etc. can be used. Among them, in order to control such adhesion amount of the acrylic resin is 5 mg / ^{m 2} or more 5000 mg / ^{m 2} or less, a method using a coater roll is particularly preferred. In addition, in order to measure the adhesion amount of the acrylic resin, the reflection infrared absorption spectrum measurement method can be used when the target value of the adhesion amount is about 500 mg / m ² or less, and the gravimetric method can be used when the target value is more.

Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.
As the aluminum alloy material, a JIS5151-H39 alloy plate having a thickness of 0.25 mm was used. As the alkaline degreasing bath, a commercially available alkaline degreasing agent “EC-370 (Nippon Paint)” was used. The operating conditions were 1.0% concentration, 1.5 kgf / cm ² spray pressure, and the pH of the bath was adjusted by blowing gaseous carbon dioxide. The bath temperature and the numerical value of pH at 25 ° C. are as described in Table 1. The etching amount was adjusted as shown in Table 1 depending on the spray time. In Examples 9 to 16 and Comparative Examples 7 to 13, acid washing with 1% sulfuric acid (immersion for 5 seconds) was performed after the alkaline degreasing. The acid washing temperature and bath composition are as shown in Table 1.

After these alkali degreasing or alkali degreasing / acid washing, intermediate water washing and final water washing were each carried out at a spray pressure of 1.5 kgf / cm ^{2 for} 5 seconds. The temperature and quality of water washing are as shown in Table 1.
The acrylic resin is a water-soluble acrylic resin (weight average molecular weight 20000, carboxyl group content = 3.5 / 1000 weight average molecular weight), solvent-based acrylic resin 1 (weight average molecular weight 50000, carboxyl group content = 1.3). / 1000 weight average molecular weight) and solvent-based acrylic resin 2 (weight average molecular weight 65000, carboxyl group content = 0 pieces / 1000 weight average molecular weight) were used. Application to the aluminum plate was performed by a roll coater, and was put into a drying furnace set at a predetermined atmospheric temperature and a wind speed of 10 m / sec for a predetermined time. The acrylic resin application conditions are as shown in Table 2.

In order to investigate the oxide film composition of the above samples, surface analysis by GDS (glow discharge emission spectroscopy) was performed. The apparatus used was JY-5000RF manufactured by Horiba, Ltd., and the thickness of the oxide film, the maximum Mg concentration, and the maximum H concentration were measured in the quantitative analysis mode. Table 3 shows the measurement results.
The amount of acrylic resin applied was determined by the gravimetric method in Examples 4, 6, 8, 11, 12, 15, 16 and Comparative Example 5, and by the calibration curve of the reflected infrared absorption spectrum for the rest. Table 3 shows the measurement results.

The following topcoat was applied to the sample thus obtained.
(Application of paint containing pigment)
Commercially available solvent-based paint for cap “White Coaching” (both containing titanium oxide pigment, content = 6.3 mass%, polyester resin, coating amount 13 g / m ² , baking temperature = 190 ° C.) Time = 600 seconds) was applied on both sides to prepare a coated sample.

The following evaluation was performed on the samples thus obtained.
(Evaluation of resin adhesion after processing)
Apply 50 mg / m ^{2 of} commercially available silicon lubricant on both sides of the above coated sample, perform draw forming (cap diameter = 38 mm, cap height = 18 mm) with a cap molding machine, and then perforate・ Screw processing was performed in this order. With respect to the obtained cap, the coating film peeling state of the perforation part, the lower end of the cap and the bead part was visually observed immediately after molding / after retorting (125 ° C. × 30 minutes). The length of the part where peeling occurred relative to the total length of the perforation part, the cap lower end and the bead part was recorded in units of%.

  As is apparent from Table 4, Examples 1 to 16 satisfy the requirements of the present invention and have high adhesion to the titanium oxide pigment-containing paint when subjected to strong processing. Therefore, in the cap molding test, immediately after molding / after retorting Both showed good results.

  On the other hand, since Comparative Examples 1 to 13 did not satisfy the requirements of the present invention, the adhesiveness to the titanium oxide-containing paint in the case of strong processing was low, and in particular, the coating film peeling was noticeable after retorting. Specifically, since the comparative example 1 is not provided with an acrylic resin, the adhesion to the white coating layer is insufficient. In Comparative Example 2, the surface Mg is not removed because the alkaline degreasing temperature is too low. On the contrary, in Comparative Example 3, the temperature is too high, resulting in excessive generation of hydroxide and poor work adhesion. In Comparative Example 4, since the amount of the acrylic resin is insufficient, the adhesion is not exhibited, and in Comparative Example 5, the amount of the acrylic resin is too large, so that the cohesive failure of the resin layer occurs. In Comparative Example 6, since the carboxyl group in the acrylic resin is insufficient, the adhesion is not exhibited. Comparative Examples 7, 10 and 12 have too much Mg in the oxide film, Comparative Example 11 has too much H in the oxide film, and Comparative Example 8 has too much Mg and H in the oxide film. In either case, the coating film adhesion is insufficient. In Comparative Examples 3 and 9, the amount of H in the oxide film is large and the thickness exceeds the regulation of the present invention, and the coating film adhesion is also inferior. In Comparative Example 13, the amount of H in the oxide film is large, the thickness does not satisfy the provisions of the present invention, and a large amount of C is adhered to the surface, so that the coating film adhesion is insufficient.

Claims (3)

In the base treatment of an aluminum plate for cap molding provided with a coating containing a pigment of 5 mass% or more with respect to the dry weight, the thickness is 200 nm or less, the surface C amount is 50 mg / m ² or less, and the oxide film / aluminum interface from the outermost surface Up to Mg: 5 mass% or less and H: 10 mass% or less on an oxide film containing Al and O as main components, and containing one or more carboxyl groups per weight average molecular weight of 1000 An aluminum plate for cap molding excellent in resin adhesion after molding processing, characterized in that a polymer of an acrylic acid compound is provided in an adhesion amount of 5 mg / m ² or more and 5000 mg / m ² or less. Alkaline degreasing with an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH of 8 or more and less than 12 at 25 ° C. with an etching amount of 10 mg / m ² or more on the aluminum alloy sheet after cold rolling. After the final washing with water having a total organic carbon content of 0.5 mass% or less without touching water exceeding 95 ° C. in the middle of the process, an aqueous solution containing one or more carboxyl groups per weight average molecular weight of 1000 Alternatively, a resin solution after molding processing according to claim 1, wherein a polymer solution of a solvent-based acrylic acid compound is applied and dried in an atmosphere of 30 ° C to 300 ° C for 1 second to 600 seconds. A method for producing an aluminum plate for cap molding with excellent adhesion. For the aluminum alloy sheet after cold rolling, an alkaline degreasing is performed with an alkaline solution having a bath temperature of 30 ° C. or more and 95 ° C. or less and a pH of 25 or more at 25 ° C. of 10 mg / m ² or more, Acid cleaning is performed with an acid having a bath temperature of 95 ° C. or less, a pH at 25 ° C. of 4.0 or less, and an Al ion concentration and an Mg ion concentration of 1 mass% or less, respectively, and touches water exceeding 95 ° C. in the middle process. And after the final washing with water having a total organic carbon content of 0.5 mass% or less, a polymer solution of an aqueous or solvent-based acrylic acid compound containing one or more carboxyl groups per weight average molecular weight of 1000 is applied. And drying in an atmosphere of 30 ° C. or more and 300 ° C. or less for 1 second or more and 600 seconds or less, excellent in resin adhesion after molding processing according to claim 1 A method for producing an aluminum plate for cap molding.