Chemical conversion treatment agent for aluminum can, aluminum can provided with chemical conversion coating film, and surface treatment method for aluminum can

Abstract

To provide a chemical conversion treatment agent that may form a coating film on a surface when being applied to an aluminum DI can, the coating film being excellent in whitening resistance during retort sterilization treatment, blackening resistance and paint adhesion during immersion retort sterilization treatment, and slipperiness for improving transportability during manufacturing of an aluminum DI can.SOLUTION: A chemical conversion treatment agent for an aluminum can comprises (A) an ion of a metal element selected from zirconium, titanium, and hafnium, (B) a phosphorus-containing ion including a phosphate ion and / or a phosphite ion, (C) a fluoride ion, and (D) a water-soluble resin, where the water-soluble resin (D) has a weight-average molecular weight of 500 or more and 100,000 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel chemical conversion treatment agent for aluminum cans, an aluminum can provided with a chemical conversion film, and a surface treatment method for an aluminum can.

Background Art

[0002] Surface treatment liquids for aluminum-containing metal materials, that is, metal materials made of aluminum or aluminum alloys, can be roughly classified into chromate types and non-chromate types. Currently, zirconium-based non-chromate type surface treatment liquids are mainly used for the surface treatment of aluminum DI (Drawing and Ironing) cans.

[0003] In aluminum DI cans, after surface treatment of the zirconium-based non-chromate type, it is common not to apply paint to the outer surface of the bottom. In recent years, due to the improvement of sterilization technology, beverages that require retort sterilization have also been filled in aluminum DI cans. For example, Patent Document 1 discloses a retort sterilization method in which sterilization and cooling are continuously performed. When the corrosion resistance is insufficient when surface treatment of the zirconium-based non-chromate type is performed, the appearance turns white and discolors. Therefore, the surface treatment film is required to have corrosion resistance that can withstand retort sterilization.

[0004] In addition, in the can manufacturing process, when transporting the cans, there is a problem that the high friction coefficient on the outer surface of the can causes poor sliding on the can surface and the can topples over, and it is required to reduce the static friction coefficient of the outer surface of the can without affecting the adhesion of the paint or ink applied to the can.

[0005] As a technique for improving slipperiness, for example, Patent Document 2 proposes a surface treatment agent for metal cans containing a water-soluble organic substance selected from phosphoric esters, alcohols, monovalent or polyvalent fatty acids, fatty acid derivatives, and mixtures thereof. Similarly, as a technique for improving slipperiness and corrosion resistance, Patent Document 3 proposes an aqueous solution containing phosphate ions, a water-soluble Zr compound and / or Ti compound, a fluoride, and a water-soluble polyamide having a tertiary amine group and / or a polyalkylene group, and having a pH of 1.8 to 4.0.

[0006] As another method for improving the problems of corrosion resistance and slipperiness, Patent Document 4 proposes a surface treatment composition for an aluminum-containing metal material containing a predetermined amount of phosphate ions, condensed phosphate ions, and a water-soluble polymer having a bisphenol skeleton. Further, as another method for improving corrosion resistance and slipperiness, Patent Document 5 proposes an aluminum-containing metal material composition containing a predetermined amount of phosphate ions, a water-soluble zirconium compound and / or titanium compound, a fluoride, and a water-soluble polymer having a bisphenol A skeleton.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in recent years, with the increase in line speed, during sterilization, hotter water (around 125 °C) comes into contact with aluminum DI cans. Therefore, even a film that can prevent the above-mentioned white discoloration has insufficient corrosion resistance, and the appearance turns black. For this reason, the techniques described in Patent Documents 2 and 3 mentioned above were also not sufficient in terms of corrosion resistance in a retort sterilization environment. Further, in the technique described in Patent Document 4, since condensed phosphoric acid is included as an essential component, there was a problem that in an acidic solution, the condensed phosphoric acid gradually decomposes and a film cannot be formed stably. Furthermore, in the technique of Patent Document 5, there were problems such as containing environmental hormone substances and insufficient corrosion resistance in a continuous retort sterilization environment.

[0009] The present invention is for solving the above-mentioned problems of the prior art. Specifically, when applied to an aluminum-containing metal material, particularly an aluminum DI can, it can form a film that is excellent in whitening resistance during retort sterilization treatment, blackening resistance during immersion retort sterilization treatment, paint adhesion, and also comprehensively satisfies excellent slipperiness for conveyance during the manufacture of aluminum DI cans. The present invention provides a chemical conversion treatment agent for aluminum cans.

Means for Solving the Problems

[0010] The present inventors earnestly studied means for solving the above-mentioned problems of the prior art. As a result, it was found that a chemical conversion treatment agent containing ions (A) containing a metal element selected from zirconium, titanium, and hafnium, phosphorus-containing ions (B) containing phosphate ions and / or phosphite ions, fluoride ions (C), and a predetermined water-soluble resin (D) can form a chemical conversion film excellent in whitening resistance during retort sterilization treatment, blackening resistance during immersion retort sterilization treatment, paint adhesion, and slipperiness, and thus the present invention was completed.

[0011] The present invention includes the following. [1] An chemical conversion treatment agent for aluminum cans, comprising ions (A) containing a metal element selected from zirconium, titanium, and hafnium, phosphorus-containing ions (B) containing phosphate ions and / or phosphite ions, fluoride ions (C), and a water-soluble resin (D), wherein the water-soluble resin (D) contains a resin represented by the following formula (1) and / or (2); [Chemical formula] [In the above formula (1) and formula (2), X represents at least one selected from the group consisting of structural units of hydroxyethyl acrylamide, diallylamine, allylamine, acrylic acid, acrylonitrile, ethylene, ethylene glycol, propylene glycol, glycerin, and ethylene oxide, and n and m represent the number average degree of polymerization, and n:m is 0:100 to 80:20.]; [2] The chemical conversion treatment agent according to [1], wherein the weight average molecular weight of the water-soluble resin (D) is 500 or more and 100,000 or less; [3] The chemical conversion treatment agent according to [1] or [2], containing the ions (A) in an amount of 10 to 1,000 ppm in terms of metal; 2]; [4] An aluminum can provided with a chemical conversion film formed by the chemical conversion treatment agent according to any one of [1] to [3]; [5] A surface treatment method for an aluminum can, comprising a step of bringing an aluminum can into contact with the chemical conversion treatment agent according to any one of [1] to [3], a step of washing the aluminum can contacted with the chemical conversion treatment agent with water, and a step of drying the washed aluminum can. [Advantages of the Invention]

[0012] According to the chemical conversion treatment agent of the present invention, a chemical conversion film excellent in slipperiness can be formed on the surface of an aluminum can, which improves the whitening resistance during retort sterilization treatment, the blackening resistance during immersion retort sterilization treatment, the paint adhesion, and the transportability during the production of aluminum DI cans. [Embodiments for Carrying out the Invention]

[0013] The present invention will be described in detail below. One embodiment of the present invention is a chemical conversion treatment agent for aluminum cans, which contains an ion (A) containing a metal element selected from zirconium, titanium, and hafnium, a phosphorus-containing ion (B) containing a phosphate ion and / or a phosphite ion, a fluoride ion (C), and a predetermined water-soluble resin (D).

[0014] <Ion (A) containing a metal element> The chemical conversion treatment agent according to this embodiment contains an ion (A) (hereinafter also simply referred to as ion (A)) containing a metal element selected from zirconium, titanium, and hafnium. Ion (A) is a chemical conversion film-forming component, which can improve the corrosion resistance and wear resistance of the base material, and further enhance the adhesion with the coating film. Examples of ion (A) include metal ions of zirconium, titanium, or hafnium; complex ions containing zirconium, titanium, or hafnium; oxide ions of zirconium, titanium, or hafnium; and the like. These ions may be contained singly or in combination of two or more in the chemical conversion treatment agent.

[0015] The concentration of ion (A) in the chemical conversion treatment agent is not particularly limited. However, from the perspective of reactivity with the surface of the aluminum can, the mass concentration in terms of metal is preferably 10 ppm or more, more preferably 20 ppm or more, preferably 1000 ppm or less, and more preferably 500 ppm or less. When two or more kinds of ion (A) are contained, the mass concentration means the total thereof.

[0016] The source of ion (A) is not particularly limited as long as it is a compound that can provide ion (A) when mixed with an aqueous medium. Examples of the source of ions containing zirconium include hexafluorozirconic acid, zirconium nitrate, zirconium oxynitrate, ammonium zirconium nitrate, zirconyl acetate, zirconyl lactate, zirconyl nitrate, zirconium carbonate, zirconium hydroxide, and zirconium oxide. Examples of the source of ions containing titanium include hexafluorotitanic acid, titanium nitrate, titanium oxynitrate, ammonium titanium nitrate, titanyl nitrate, titanium hydroxide, titanium oxide, and ammonium titanium fluoride. Examples of the source of ions containing hafnium include hafnium trifluoromethanesulfonate, hexafluorohafnic acid, hafnium nitrate, hafnium oxide, etc. When these can take the form of salts, the salts may be used. These sources may be used alone or in combination of two or more. From the viewpoint of film-forming ability, hexafluorozirconic acid, hexafluorotitanic acid, hexafluorohafnic acid, and their salts are preferred as the source of ion (A).

[0017] <Phosphorus-containing ion (B)> The chemical conversion treatment agent according to this embodiment contains a phosphorus-containing ion (B) (hereinafter also simply referred to as ion (B)) containing phosphate ions and / or phosphite ions. Ion (B) is a chemical conversion film-forming component and contributes to the improvement of the corrosion resistance and retort resistance of the base material. In addition to phosphate ions and / or phosphite ions, ion (B) may contain ions such as hypophosphite ions, polyphosphate ions, and phosphonate ions. Ion (B) may be contained in the chemical conversion treatment agent in one kind or two or more kinds.

[0018] The concentration of ion (B) in the formation treatment agent is not particularly limited, but in terms of the mass concentration in terms of phosphorus, from the viewpoint of reactivity with the surface of the aluminum can, it is preferably 10 ppm or more, more preferably 20 ppm or more, and preferably 3000 ppm or less, more preferably 1000 ppm or less, and even more preferably 400 ppm or less. When two or more kinds of ions (B) are contained, the mass concentration means their total.

[0019] The source of the phosphorus-containing ion (B) is not particularly limited as long as it is a compound that can provide ion (B) when mixed with an aqueous medium, and either an inorganic phosphorus compound or an organic phosphorus compound can be used, and it may be an inorganic phosphoric acid, an organic phosphoric acid, and their salts (for example, metal salts such as alkali metal salts and alkaline earth metal salts, ammonium salts, etc.). Specifically, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, and their salts, etc. can be mentioned. For example, phosphoric acid, sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, ammonium phosphate, calcium phosphate; phosphorous acid, disodium hydrogen phosphite; hypophosphorous acid, sodium hypophosphite, ammonium hypophosphite; tripolyphosphoric acid, tetraphosphoric acid, sodium tripolyphosphate, sodium tetrapolyphosphate, etc. can be mentioned, but it is not limited thereto. These sources of the phosphorus-containing ion (B) may be used alone or in combination of two or more.

[0020] <fluoride ion (C)> The formation treatment agent according to this embodiment contains fluoride ions (C) (hereinafter also simply referred to as ions (C)). Ions (C) serve as an etching agent for the base material. The concentration of ions (C) in the formation treatment agent is not particularly limited, but in terms of the mass concentration in terms of fluorine, from the viewpoint of reactivity with the surface of the aluminum can, it is preferably 30 ppm or more, more preferably 50 ppm or more, and from the viewpoint of obtaining a good appearance, it is preferably 1500 ppm or less, more preferably 1000 ppm or less, and even more preferably 600 ppm or less.

[0021] The source of fluoride ions (C) is not particularly limited as long as it is a compound that can provide ions (C) when mixed in an aqueous medium (hereinafter also referred to as a fluorine-containing compound). Examples of fluorine-containing compounds include fluorides such as hydrofluoric acid, ammonium fluoride, boric acid fluoride, ammonium hydrogen fluoride, sodium fluoride, potassium fluoride, and sodium hydrogen fluoride; complex fluorides such as hydrofluorosilicic acid, zinc hydrofluorosilicate, manganese hydrofluorosilicate, magnesium hydrofluorosilicate, nickel hydrofluorosilicate, iron hydrofluorosilicate, calcium hydrofluorosilicate, hexafluorozirconic acid, hexafluorotitanic acid, and hexafluorohafnic acid, but are not limited thereto. These sources of fluoride ions (C) may be used alone or in combination of two or more. Note that hexafluorozirconic acid, hexafluorotitanic acid, and hexafluorohafnic acid also correspond to the source of ions (A) and contribute to the concentrations of ions (A) and ions (C) respectively.

[0022] <Water-soluble resin (D)> The formation treatment agent according to this embodiment contains a predetermined water-soluble resin (D) (hereinafter also simply referred to as resin (D)). Resin (D) is represented by the following formula (1) and / or the following formula (2).

Chemical formula

[0023] In the above formulas (1) and (2), X represents at least one selected from the group consisting of structural units of hydroxyethyl acrylamide, diallylamine, allylamine, acrylic acid, acrylonitrile, ethylene, ethylene glycol, propylene glycol, glycerin, and ethylene oxide, and n and m represent the number average degree of polymerization, and n:m is 0:100 to 80:20. It is considered that the chemical conversion treatment agent according to the present embodiment can form a chemical conversion film excellent in adhesion to a metal substrate and corrosion resistance in a retort sterilization environment due to the action of the amide group contained in the resin (D). The resin (D) may be contained only one kind or two or more kinds in the chemical conversion treatment agent.

[0024] The resin (D) is not particularly limited as long as it contains the above structural units and has the above number average degree of polymerization. From the viewpoint of retort resistance, n:m is preferably 0:100 to 80:20, more preferably 0:100 to 60:40, and still more preferably 0:100 to 20:80.

[0025] The resin (D) preferably has a primary amide group of 0.01 mol or more per 100 g of the resin, more preferably 0.1 mol or more, and still more preferably 0.15 mol or more.

[0026] The mass concentration of the resin (D) in the chemical conversion treatment agent is preferably 20 ppm or more, more preferably 50 ppm or more, from the viewpoint of forming a film with good retort resistance in terms of resin solids, and preferably 5000 ppm or less, more preferably 3000 ppm or less, from the viewpoint of film-forming properties.

[0027] From the viewpoint of forming a film with good retort resistance, the resin (D) preferably has a weight average molecular weight of 500 or more, more preferably 5,000 or more. Also, from the viewpoint of film-forming properties, the weight average molecular weight is preferably 100,000 or less, more preferably 50,000 or less. 。

[0028] <Mass ratio of resin (D) / ion (A)> In the formation treatment agent, the mass ratio of resin (D) / ion (A) is preferably 0.1 or more, more preferably 1.0 or more, preferably 50 or less, and more preferably 30 or less from the viewpoint of retort resistance.

[0029] <Aqueous medium> The formation treatment agent according to this embodiment may contain an aqueous medium. The aqueous medium is not particularly limited as long as it is water or a mixture of water and a water-miscible organic solvent (containing 50% by volume or more of water based on the volume of the aqueous medium). The water-miscible organic solvent is not particularly limited as long as it is miscible with water. For example, ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, and isopropanol; ether solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; pyrrolidone solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone, etc. These water-miscible organic solvents may be mixed with water alone or two or more of them may be mixed with water.

[0030] <Other components> The formation treatment agent according to this embodiment may, in addition to the above components, optionally contain, as other components, additives commonly used in formation treatment agents. Examples of other components include sources of metal ions other than ion (A), silicon-containing compounds, water-soluble resins or water-dispersible resins other than water-soluble resin (D), chelating agents, surfactants, pH adjusters, etc. These other components may be used alone or in combination of two or more. Note that these other components can be used within a range that does not inhibit the effects of the present invention.

[0031] <Source of metal ions other than ion (A)> Examples of the sources of metal ions other than ion (A) that can be incorporated into the formation treatment agent according to the present embodiment include, but are not limited to, compounds that can supply ions containing metal elements such as zinc, magnesium, calcium, aluminum, manganese, iron, cobalt, and copper. The source of metal ions other than ion (A) may contain only one type or two or more types.

[0032] <Silicon-containing compound> Examples of the silicon-containing compound that can be incorporated into the formation treatment agent according to the present embodiment include, but are not limited to, silica, water-dispersible silica, silicates of alkali metals or alkaline earth metals, alkyl silicate esters, silane coupling agents, etc. Specifically, potassium silicate, sodium silicate, silicic acid dimer, silicic acid oligomer, colloidal silica, tetramethoxysilane, methyltrimethoxysilane, tetraethoxysilane, glycidoxypropyltriethoxysilane, aminopropyltriethoxysilane, epoxycyclohexylethyltrimethoxysilane, etc. can be mentioned, but are not limited thereto. The silicon-containing compound may contain only one type or two or more types.

[0033] <Water-soluble resin or water-dispersible resin other than water-soluble resin (D)> Examples of the water-soluble resin or water-dispersible resin other than water-soluble resin (D) that can be incorporated into the formation treatment agent according to the present embodiment include, but are not limited to, urethane resin, acrylic resin, epoxy resin, phenol resin, amine resin, etc. The water-soluble resin or water-dispersible resin other than water-soluble resin (D) may be incorporated alone or in combination of two or more.

[0034] <Chelating agent> Examples of the chelating agent that can be incorporated into the formation treatment agent according to the present embodiment include, but are not limited to, citric acid, gluconic acid, oxalic acid, and organic phosphonic acid. By adding the chelating agent, it is possible to improve the destabilization of the treatment liquid caused by metal ions such as copper ions and manganese ions, which are ions of the eluted alloy components.

[0035] <Surfactant> Examples of the surfactant that can be incorporated into the chemical conversion treatment agent according to this embodiment include nonionic surfactants, ionic surfactants such as cationic, anionic, and amphoteric surfactants.

[0036] <pH of the chemical conversion treatment agent> The pH of the chemical conversion treatment agent according to this embodiment is not particularly limited, but the pH value at the temperature when contacting the surface of the aluminum can is preferably 1.5 or more, more preferably 2.0 or more, preferably 6.0 or less, and more preferably 5.0 or less at 25°C. When within the above pH range, a good film can be obtained by appropriate etching. The pH can be measured with a commercially available pH meter. The pH of the chemical conversion treatment agent can be adjusted by using acids such as phosphoric acid, nitric acid, hydrochloric acid, hydrofluoric acid, organic acids, and alkalis such as sodium hydroxide, sodium carbonate, ammonium hydroxide, and amines as pH adjusters, but is not limited thereto. One or more pH adjusters may be used.

[0037] <Method for producing the chemical conversion treatment agent> The chemical conversion treatment agent according to this embodiment can be produced by blending a predetermined amount of a source of ion (A), a source of phosphorus-containing ion (B), a source of fluoride ion (C), and a predetermined water-soluble resin (D) as raw materials in an aqueous medium.

[0038] <Method for forming the chemical conversion film> The surface treatment of the metal with the above chemical conversion treatment agent is not particularly limited and can be carried out by bringing the chemical conversion treatment agent into contact with the surface of the aluminum can or on the surface under normal treatment conditions. The chemical conversion treatment method is not particularly limited, and examples include dipping method, spraying method, roll coating method, etc.

[0039] ​The treatment temperature in the above chemical conversion treatment is not particularly limited as long as a desired chemical conversion film can be obtained, but it is preferably 30°C or higher, more preferably 35°C or higher, preferably 70°C or lower, and more preferably 60°C or lower. Also, the chemical conversion time in the above chemical conversion treatment is not particularly limited as long as a desired chemical conversion film can be obtained, but it is preferably within the range of 5 seconds or more and 200 seconds or less. The lower limit is more preferably 10 seconds, and the upper limit is more preferably 100 seconds.

[0040] The surface of the above aluminum can may be subjected to pretreatment such as degreasing and water washing before being subjected to the chemical conversion treatment with the above chemical conversion treatment agent. A post-chemical conversion water washing treatment may be performed after the chemical conversion treatment. The above degreasing treatment is performed to remove oil and dirt adhering to the surface of the aluminum can, and is usually spray-treated at 40 to 80°C for about 10 to 120 seconds using a known acidic or alkaline degreasing agent. If desired, a preliminary degreasing treatment can also be performed before the degreasing treatment. The above post-degreasing water washing treatment is performed by spraying with a large amount of washing water one or more times to wash the degreasing agent after the degreasing treatment. The above post-chemical conversion water washing treatment is performed one or more times to prevent adverse effects on the adhesion, corrosion resistance, etc. after various coatings. In this case, it is appropriate that the final water washing is performed with pure water. In this post-chemical conversion water washing treatment, either spray water washing or immersion water washing may be used, or these methods can be combined for water washing. After the above post-chemical conversion water washing treatment, drying can be performed as necessary according to a known method, and then various coatings can be applied.

[0041] The aluminum-containing metal material forming the aluminum can is not particularly limited, and includes aluminum, and materials made of aluminum-containing alloys such as aluminum-manganese alloys, aluminum-magnesium alloys, and aluminum-silicon alloys, such as plate materials, bar materials, pipe materials, and wire materials. For example, 3000 series aluminum alloys, 5000 series aluminum alloys, 6000 series aluminum alloys, etc. can be mentioned. This metal material There are no restrictions on the dimensions and shapes. As an aluminum can, it is preferably an aluminum DI (Drawing and Ironing) can.

Examples

[0042] The present invention will be described in more detail by the following examples, but the present invention is not limited by the following examples.

[0043] Evaluation method (1) Resistance to whitening (retort 1) Regarding the corrosion resistance (retort resistance) of aluminum DI cans, 350 mL of deionized water was filled into the aluminum DI cans prepared by the methods of the following Examples 1 - 22 and Comparative Examples 1 - 5, and the bottom part of the can was exposed to steam at 125°C for 30 minutes with the bottom facing downwards. The degree of discoloration (whitening) after exposure was visually evaluated according to the following evaluation criteria. S: No whitening on both the outer and inner surfaces of the can. A: No whitening on the outer surface of the can, but slight whitening on the inner surface. B: Whitening on a part of the outer surface of the can, and also whitening on the inner surface. C: Whitening on the entire surface of the can. (2) Resistance to blackening (retort 2) Regarding the corrosion resistance (retort resistance) of aluminum DI cans, the aluminum DI cans prepared by the methods of the following Examples 1 - 22 and Comparative Examples 1 - 5 were immersed in deionized water and heated at 125°C for 30 minutes. The degree of discoloration (blackening) after heating was visually evaluated according to the following evaluation criteria. S: No blackening on both the outer and inner surfaces of the can. A: No blackening on the outer surface of the can, but slight blackening on the inner surface. B: Blackening on a part of the outer surface of the can, and also blackening on the inner surface. C: Blackening on the entire surface of the can. (3) Paint adhesion The paint adhesion of aluminum DI cans was tested as follows. An epoxyurea-based can paint was applied to the surface of an aluminum DI can prepared by the method of Examples 1-22 and Comparative Examples 1-5 below, with a thickness of 5 to 7 μm, and baked at 215° C. for 4 minutes. The can was cut into 5×150 mm strips and heat-pressed with a polyamide film to prepare a test piece. The test piece was peeled off by a 180° peel test method, and the peel strength at that time was evaluated. The higher the peel strength, the better the paint adhesion. Generally, a peel strength of 4.0 kgf / 5 mm width or more is good for practical use. (4) Slipperiness The slipperiness was evaluated by measuring the static friction coefficient of the outer surface of the can. Specifically, three aluminum DI cans prepared by the methods of Example 1-22 and Comparative Example 1-5 below were stacked in a bale shape, tilted at a speed of 3 degrees per second, and the friction angle θ when the cans started to slide was measured. The static friction coefficient was calculated from the formula: static friction coefficient μ=tan θ. The lower the static friction coefficient, the better the slipperiness, and generally, a static friction coefficient of 1.0 or less is considered to be good.

[0044] Example 1 An aluminum DI can made by DI processing an aluminum alloy plate (A3004) was degreased with an 8% aqueous solution of an acidic degreaser (trademark: Palclean 501, manufactured by Nihon Parkerizing Co., Ltd.) by spraying at 75°C for 60 seconds, then rinsed and cleaned with tap water. This cleaned surface was sprayed at 40°C for 10 seconds with chemical conversion treatment agent 1 having the following composition. This was then rinsed with tap water, and further treated with a deionized water solution having a resistance of 3,000,000 Ωcm or more. After spraying with water for 10 seconds, the aluminum DI can was dried for 2 minutes in a hot air drying oven at 200° C. Thereafter, the whitening resistance, blackening resistance, adhesion and slipperiness of the aluminum DI can were measured and evaluated by the above-mentioned methods (1) to (4). The evaluation results are shown in Table 2.

[0045] Chemical conversion coating agent 1 Zr ions (A): 100 ppm P ion (B): 100 ppm F ions (C): 175 ppm ·Water-soluble resin 1(D): 500ppm In addition, 40% zirconium hydrofluoric acid (H 2 ZrF 6 ), 75% phosphoric acid (H 3 PO 4 ), 55% hydrofluoric acid (HF), and water-soluble resin 1 were used. The water-soluble resin 1 is a water-soluble resin in which, in the above formula (1), X = diallylamine, n:m = 50:50, weight average molecular weight = 10,000, and the number of moles of primary amide groups per 100 g of the resin is 0.60. The chemical conversion treatment agent was adjusted to pH 2.5 using nitric acid.

[0046] Examples 2-19, Comparative Examples 1-3 The chemical conversion treatment agents of Examples 2-19 and Comparative Examples 1-3 were prepared to have the ion concentrations and pH values shown in Table 1 using the respective components described for the chemical conversion treatment agent 1 for the components other than the water-soluble resin. The water-soluble resin was prepared using the water-soluble resin shown in Table 1. The object to be treated, the treatment method, and the evaluation method were carried out in the same manner as in Example 1. The evaluation results are shown in Table 2.

[0047] Examples 20-22 The chemical conversion treatment agents of Examples 20-22 were prepared to have the ion concentrations and pH values shown in Table 1 using the respective components described for the chemical conversion treatment agent 1 for the components other than ion (A) or ion (B). Titanium hydrofluoric acid was used as the source of Ti ions for ion (A), hafnium trifluoromethanesulfonate was used as the source of Hf ions, and phosphorous acid was used as the source of phosphite ions for ion (B), and they were prepared to have the ion concentrations shown in Table 1. The object to be treated, the treatment method, and the evaluation method were carried out in the same manner as in Example 1. The evaluation results are shown in Table 2.

[0048] Comparative Example 4 An aluminum DI can was treated by the method described in Example 1 of JP-A-7-331276. Thereafter, the whitening resistance, blackening resistance, adhesion, and slipperiness of this aluminum DI can were evaluated by the above method. The evaluation results are shown in Table 2.

[0049] Comparative Example 5 The aluminum DI cans were processed by the method described in Example 1 of JP-A-9-031404. Thereafter, the whitening resistance, blackening resistance, adhesion, and slipperiness of these aluminum DI cans were evaluated by the above method. The evaluation results are shown in Table 2.

[0050]

Table 1

[0051]

Table 2

[0052] As is clear from the results in Table 2, the corrosion resistance, paint adhesion, and lubricity of the chemical conversion-treated aluminum cans obtained with the chemical conversion treatment agents of Examples 1 to 22 were all excellent. On the other hand, the performance of the chemical conversion-treated aluminum cans obtained with the chemical conversion treatment agents of Comparative Examples 1 to 5 was inferior, particularly in terms of blackening resistance (retort).

Claims

1. A chemical conversion treatment agent for aluminum cans, comprising ions (A) containing a metal element selected from zirconium, titanium, and hafnium, phosphorus-containing ions (B) containing phosphate ions and / or phosphite ions, fluoride ions (C), and a water-soluble resin (D), wherein the water-soluble resin (D) contains a resin represented by the following formula (1) and / or (2). 【Chemical 1】 〔In the above formula (1) and formula (2), X represents at least one selected from the group consisting of structural units of hydroxyethyl acrylamide, diallylamine, allylamine, acrylic acid, acrylonitrile, ethylene, ethylene glycol, propylene glycol, glycerin, and ethylene oxide, and n and m represent the number average degree of polymerization, and n:m is 0:100 to 80:20.〕

2. The chemical conversion treatment agent according to claim 1, wherein the weight average molecular weight of the water-soluble resin (D) is 500 or more and 100,000 or less.

3. The chemical conversion treatment agent according to claim 1, containing the ions (A) in an amount of 10 to 1,000 ppm in terms of metal.

4. An aluminum can provided with a chemical conversion film formed by the chemical conversion treatment agent according to any one of claims 1 to 3.

5. A surface treatment method for an aluminum can, comprising a step of bringing an aluminum can into contact with the chemical conversion treatment agent according to any one of claims 1 to 3, a step of washing the aluminum can contacted with the chemical conversion treatment agent with water, and a step of drying the washed aluminum can.

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