JP2011005425A - Lubricating film coating aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating film coating aluminum material which is excellent in molding processability and weldability after molding and which is excellent in anti-corrosiveness resulting from high coating film adhesiveness even to the coating after molding without increasing steps.SOLUTION: The lubricating film coating aluminum material is provided with an aluminum substrate and a lubricating film containing an alkali de-coating type urethane resin, a water-soluble zirconium compound and a lubricant, which is formed on at least one surface of the aluminum substrate. The material contains 1-50 mg/mof the water-soluble zirconium compound in the lubricating film in terms of metal zirconium. The lubricant has an average particle size of 0.1-30 μm and is included by 1-30 pts.wt. to 100 pts.wt. of the alkaline de-coating type urethane resin. In the aluminum substrate surface after the alkali treatment, the maximum absorption of peak which appears on the peak of around 1,700 cmof FT-IR spectrum is 1% or less and 0.5 mg/mor more of the zirconium compound layer in terms of metal zirconium remains.

Description

  The present invention relates to an aluminum material for lubricating film coating for molding processing which is excellent in press formability, film removal property and corrosion resistance after film removal, and is used in beverage containers, electrical and electronic equipment members, automobile body sheet materials, building materials, and the like. .

  Aluminum plates or aluminum alloy plates (hereinafter referred to as “aluminum substrates”) have a wide range of fields such as beverage containers, electrical components, and transport aircraft components due to their excellent corrosion resistance and design, light weight and excellent workability. Used in. In recent years, in particular, since greenhouse gas emission regulations have become more stringent, the use of aluminum plates for the purpose of weight reduction is increasing in the field of transport aircraft.

  In applying the aluminum substrate to the above-mentioned use, it is usually formed by press working. In severe processing conditions, surface friction resistance increases and deformation resistance increases, resulting in insufficient strength at a portion where excessive deformation resistance is applied, resulting in processing cracks. Therefore, for the purpose of preventing such processing cracks, a method of applying a high-viscosity lubricant and press forming is employed. Such press-molded products are painted for the purpose of imparting corrosion resistance, etc., but if the lubricant applied during press processing remains attached before coating, the processability is inferior and is removed. There is a need to. As a method for removing the lubricant, degreasing is performed by using an organic solvent or an alkali treatment. However, degreasing using an organic solvent not only adversely affects the health of workers, but many of them are environmentally hazardous substances. I want to avoid the method as much as possible. On the other hand, it is difficult to completely remove the highly viscous lubricant in the alkali treatment, and the remaining lubricant may adversely affect the subsequent treatment such as coating.

  As a press molding method that does not use a high-viscosity lubricant, a method has been developed in which a non-delaminating lubricating film is provided on an aluminum substrate for press molding. However, since the lubricating film remains on the metal surface even after press molding, it has been difficult to apply to applications that undergo processing such as welding and painting after processing. As a solution to this problem, Patent Documents 1 and 2 propose a film removal type lubricating film that can easily remove the lubricating film by alkali treatment after press molding. However, when this alkali film removal type lubricating film is applied to a product to be finally coated, a layer that improves adhesion to the film applied after the alkali treatment is formed on the surface where the lubricating film is removed. It may not exist, and problems may occur in adhesion and corrosion resistance. In this case, adhesion and corrosion resistance are improved by applying a base treatment such as a chemical conversion film to the surface of the aluminum substrate before providing the lubricating film, but this requires an increase in the number of processes and installation of equipment. There was a demerit that a great cost was required.

JP 2003-27256 A JP 2007-98582 A

  The present invention solves these problems and is excellent in molding processability and post-molding weldability, and also has excellent corrosion resistance by having high coating film adhesion even after coating without increasing the number of steps. An object is to provide a painted aluminum material.

  In the present invention, an aluminum film is coated with an aqueous paint containing an alkaline film-removing urethane resin, a water-soluble zirconium compound and a lubricant as essential components, and dried to form a lubricating film on the surface of the aluminum substrate. . The water-soluble zirconium compound forms a chemical bond with aluminum and the carboxyl group of the alkali film-removing urethane resin. Here, the reaction with aluminum is faster than the reaction with urethane resin, and the surface of the aluminum substrate is preferentially occupied by the zirconium compound. The alkali film-removing urethane resin, the zirconium compound bonded to the resin, and the lubricant are removed from the aluminum substrate when the coated aluminum material is subjected to alkali treatment. However, some zirconium compounds bonded to the aluminum substrate remain as a layer on the substrate even after the alkali treatment. The remaining zirconium compound layer is very thin and does not have an adverse effect on spot welding or electrodeposition coating of painted aluminum material, and it exhibits excellent adhesion to the coating film formed on this layer. Corrosion resistance.

  Thus, the present inventors can improve the adhesion with the coating film provided after the alkali treatment and improve the corrosion resistance by forming a zirconium compound layer that does not dissolve in the alkaline solution during the formation of the lubricating film. I found. In addition, acrylic resin can be used as the alkali film-removing resin, but there may be cases where sufficient moldability cannot be obtained, such as galling under severe molding conditions such as deep drawing and ironing. Urethane resin is suitable.

The present invention relates to an aluminum substrate comprising an aluminum plate or an aluminum alloy plate, and a lubricating film having a dry film thickness of 0.05 to 10 μm formed on at least one surface of the aluminum substrate, wherein A lubricant film comprising a film-type urethane resin, a water-soluble zirconium compound and a lubricant, wherein the alkali film-removable urethane resin contains a hydrophilic group, and an acid value due to the hydrophilic group is 25 mg-KOH / g or more. In addition, an oxide film having a thickness of 100 mm or less exists on the surface of the aluminum substrate, the water-soluble zirconium compound is contained in the lubricating film in an amount of 1 to 50 mg / m ^{2 in} terms of metal zirconium, and the lubricant is 0.1 to It has an average particle diameter of 30 μm and is contained in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the alkali film-removing urethane resin. , When removing the alkali removal membrane type urethane resin and lubricant in the lubricating layer by alkali treatment, the in aluminum substrate surface, a peak maximum absorption rate appearing in ^-One 1700cm of FT-IR spectrum than 1% In addition, a lubricating coating aluminum material characterized in that a zirconium compound layer of 0.5 mg / m ² or more in terms of metallic zirconium remains.

  In the present invention, the water-soluble zirconium compound is an ammonium salt or an alkali metal salt of zirconium carbonate.

  According to a third aspect of the present invention, in the third aspect, the lubricant contains at least one of a polyolefin wax and a fluororesin.

  According to the present invention, an aluminum material with a lubricating coating is provided that has excellent processability and post-molding weldability, and has high coating film adhesion even after coating without increasing the number of steps, thereby providing excellent corrosion resistance. it can.

Hereinafter, the present invention will be described in detail for each element.
A. Lubricant-coated aluminum material The lubricant-coated aluminum material according to the present invention includes an aluminum substrate made of an aluminum plate or an aluminum alloy plate, and a lubricant film coated on at least one surface of the aluminum substrate.

B. Aluminum substrate As the aluminum substrate used in the present invention, a pure aluminum plate and an aluminum alloy plate containing one or more of iron, copper, manganese, silicon, magnesium, zinc, chromium, nickel and the like can be used. . Examples of the aluminum alloy plate include JIS 1050, 1100, 1085, 1200, 2002, 2037, 3003, 5052, 5082, 5182, 6009, 6010, 6015, 6022, 7072, and 7075. Although the thickness of an aluminum substrate is not specifically limited, A 0.1-5.0 mm thing is used suitably.

  In applying the present invention, the oil adhering to the surface of the aluminum substrate in the manufacturing process may adversely affect the formation of the lubricating film. Therefore, degreasing with an alkaline aqueous solution and / or an acidic aqueous solution is required for the purpose of removing these oils. Preferably it is done. In addition, when the oxide film on the surface of the aluminum substrate is thick, for example, when the lubricating coating aluminum coating material of the present invention is bonded to other parts through an adhesive, the oxide film cohesively breaks down, resulting in an adhesive strength. Is damaged. Therefore, the thickness of the oxide film is set to 100 mm or less. Examples of the method for removing the oxide film include washing using an alkaline aqueous solution and / or an acidic aqueous solution.

  For these degreasing and washing, a method performed as a normal aluminum treatment method may be used, and a commercially available treatment solution may be used. Examples of the alkaline aqueous solution include sodium hydroxide and potassium hydroxide, and examples of the acidic aqueous solution include sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, a mixed solution of nitric acid and hydrofluoric acid, and the like.

C. Lubricating film The lubricating film used in the present invention is obtained by applying an alkaline film-removing urethane resin, a water-soluble zirconium compound and a lubricant as essential components, and applying and drying an aqueous paint containing these on an aluminum substrate. The film thickness of the lubricating film is in the range of 0.05 to 10 μm in terms of dry film thickness. If the thickness is less than 0.05 μm, the film is too thin and galling occurs during molding, and the moldability cannot be satisfied. When the thickness exceeds 10 μm, peeling powder is generated from the dried film, which may increase the maintenance frequency of the mold and deteriorate the working environment.

C-1. Alkali film-removable urethane resin The alkali film-removable urethane resin contained in the lubricating film of the present invention comprises (i) a compound having at least two isocyanate groups per molecule and (ii) at least two molecules per molecule. A copolymer of a polyol compound having an active hydrogen group and (iii) a compound having at least one active hydrogen group in the molecule and containing a hydrophilic group such as a carboxyl group or a sulfonic acid group is there. About (iii), it is preferable to contain a carboxyl group as a hydrophilic group from a reactive point with a water-soluble zirconium compound.

  Examples of the compound (i) containing at least two isocyanate groups per molecule include 2,4- or 2,6-triethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2 -Propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl carbonate Aliphatic diisocyanates such as proate, 1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5, -Trimethylcyclohexyl isocyanate (IPDI), 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4-bis (isocyanatomethyl) cyclohexane, 1, Alicyclic diisocyanates such as 3-bis (isocyanatomethyl) cyclohexane and norbornene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, dianisidine diiso Cyanates, aromatic diisocyanates such as 4,4′-diphenyl ether diisocyanate, 1,3 or 1,4-xylylene diisocyanate or mixtures thereof, ω, ω′-diisocyanate-1,4-diethylbenzene, 1,3- or 1, Aro-aliphatic diisocyanates such as 4-bis (1-isocyanate-1-methylethyl) benzene or mixtures thereof, 1,3,5-triisocyanate hexane, 1,3,5-triisocyanate benzene, 2,4,6 -Triisocyanate toluene, triisocyanate, such as 1,3,5-triisocyanate hexane, etc. are mentioned. Although these compounds having an isocyanate group are used, aromatic, araliphatic, or alicyclic isocyanate compounds are preferred in order to achieve sufficient processability.

  Examples of the polyol compound (ii) having at least two active hydrogen groups per molecule include compounds in which the active hydrogen group is an amino group, a hydroxyl group, or a mercapto group. Here, a compound in which the active hydrogen group is a hydroxyl group is preferable from the viewpoint of the reaction rate with the isocyanate group and the mechanical properties after coating. Examples of the compound in which the active hydrogen group is a hydroxyl group include dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, 1,6 -Polyester obtained by reacting glycols such as hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylol heptane, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, etc. Polyol: A polymer obtained by polymerizing an oxirane compound such as ethylene oxide using a polyol such as water, ethylene glycol, propylene glycol, trimethylolpropane, or glycerin as an initiator. Ether polyols; polyether ester polyols obtained by reacting dibasic acids such as terephthalic acid, isophthalic acid, adipic acid, azelaic acid, and sebacic acid with the above polyether polyols; terephthalic acid, isophthalic acid, adipic acid, azelaic acid , Polyester amide polyols obtained by reacting dibasic acids such as sebacic acid with aliphatic diamines such as ethylenediamine, propylenediamine and hexamethylenediamine and the above polyether polyols; hydroxyethyl acrylate, hydroxypropyl acrylate, acrylic acid By copolymerizing a polymerizable monomer having one or more hydroxyl groups in one molecule such as hydroxybutyl or the corresponding methacrylic acid derivative and acrylic acid, methacrylic acid or an ester thereof. Acrylic polyols; ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,8-nonane One or more glycols selected from the group consisting of diol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol-A and dimethyl carbonate, ethylene Polycarbonate polyol obtained by reacting carbonate, diphenyl carbonate, phosgene and the like; polyhydroxyalkane obtained by copolymerizing isoprene, butadiene or butadiene and acrylamide; Castor oil; polyurethane polyols, or mixtures thereof. In order to achieve good alkali film-removability, polyester polyol and polyurethane polyol composed of polyester polyol are preferable. The compounds having various active hydrogen groups are used, and polyester polyol and polyurethane polyol composed of polyester polyol are preferable in order to achieve good alkali solubility. In addition, in order to achieve alkali solubility at a low temperature such as room temperature, an ethylene glycol is reacted with an aliphatic dibasic acid such as adipic acid, azelaic acid, sebacic acid or a dialkyl ester thereof or a mixture thereof. Polyester polyols obtained by making them are preferable.

  Examples of the compound having at least one active hydrogen group in the molecule (iii) and having a hydrophilic group such as a carboxyl group and a sulfonic acid group include 2,2-dimethylolpropionic acid, Carboxyl group-containing compounds such as 2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxybenzoic acid, 3,4-diaminobenzoic acid or derivatives thereof; Polyester polyols obtained by the above; sulfonic acid group-containing compounds such as phenol sulfonic acid or derivatives thereof; or polyols obtained by copolymerizing these; and the like, in the copolymerization, these hydrophilic group-containing compounds Are used alone or in combination of two or more.

  In the synthesis of urethane polymers, ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine are used for the purpose of increasing the molecular weight. Diamines such as 3,3′-dimethyl-4,4′-dicyclohexylmethanediamine and 1,4-cyclohexanediamine; polyamines such as diethylenetriamine, dipropylenetriamine, triethylenetetramine, and tetraethylenepentamine; hydroxyethylhydrazine , Hydroxyethyldiethylenetriamine, 2-[(2-aminoethyl) amino] ethanol, compounds having an amino group and a hydroxyl group such as 3-aminopropanediol, hydrazines, acid hydrazides; Agents and alcohols such as methyl alcohol; may be added in accordance with such coalescents object; ethers such as butyl cellosolve; butyl cellosolve glycol ether esters such as acetate.

  The above is an example of an alkali film-removing urethane resin material, and the material and manufacturing method of the urethane resin are not particularly limited as long as they are alkali film-removing type.

  The lubricating film is formed by coating with a water-based paint. In order to dissolve or disperse the alkaline film-removable urethane resin well in the aqueous solution, hydrophilic groups such as carboxyl groups and sulfone groups contained in the alkali film-removed urethane resin are used. Must be neutralized with sodium hydroxide, potassium hydroxide, ammonia, n-propylamine or the like. By using such a neutralizing agent, alkali solubility of the alkali film-removing urethane resin can be achieved. The neutralizing agent used in the present invention preferably contains sodium hydroxide or potassium hydroxide.

  The alkali film-removing urethane resin contains hydrophilic groups such as carboxyl groups and sulfonic acid groups, and the acid value of these hydrophilic groups is 25 mg-KOH / g or more. If this oxidation is less than 25 mg-KOH / g, the oxidation is too little to obtain good alkali film removal properties due to the alkali component. The acid value is a compound of (iii) that constitutes an alkali film-removing urethane resin, that is, has at least one active hydrogen group in the molecule and has a hydrophilic group such as a carboxyl group or a sulfonic acid group. It can change by adjusting the ratio in the copolymer of the compound to contain. In addition to the alkali film removal type urethane resin, an alkali film removal type acrylic resin, polyester resin, polyvinyl alcohol resin or the like may be added as long as the performance of the lubricating film is not deteriorated. The alkali film-removing urethane resin is dissolved or dispersed in water using a homogenizer, a mixer or the like to form an aqueous paint.

C-2. Water-soluble zirconium compound The water-soluble zirconium compound contained in the lubricating film used in the present invention is added to the water-based paint. This water-soluble zirconium compound reacts with the functional groups of aluminum and urethane resin, and zirconium carbonate, zirconium acetate, zirconium phosphate, zirconium fluoride; ammonium salts thereof; alkali metal salts thereof are preferably used. . From the viewpoints of stability to the water-based paint and environmental load, an ammonium salt or alkali metal salt of zirconium carbonate is particularly preferably used.

The water-soluble zirconium compound is contained in the lubricating film in an amount of 1 to 50 mg / m ² or more in terms of metal zirconium. If it is less than 1 mg / m ^{2 in} terms of metal zirconium, the adhesion of the lubricating film to the aluminum substrate is weak and sufficient corrosion resistance cannot be obtained after processing. On the other hand, if it exceeds 50 mg / m ^{2 in} terms of metal zirconium, the lubricating film becomes brittle, causing deterioration of formability, or when the lubricating film is bonded with an adhesive in a state where the lubricating film is provided, There is a problem that the adhesive strength is reduced due to the tendency to cohesive failure.

In addition, the zirconium compound remaining on the substrate when the lubricating film coated aluminum plate is subjected to alkali treatment is 0.5 mg / m ² or more in terms of metal zirconium. If it is less than 0.5 mg / m ² , sufficient adhesion of the lubricating film to the aluminum substrate cannot be ensured in the coating applied after the alkali treatment.

C-3. Lubricant As the lubricant added to the lubricating film in the present invention, those having an average particle diameter of 0.1 to 30 μm are used. As the type of lubricant, at least one of polyolefin wax and fluororesin is preferably used. Examples of the polyolefin wax include polyethylene wax, polypropylene wax, modified polyethylene, and the like, or a mixture thereof. Examples of the fluororesin include polytetrafluoroethylene, polyhexafluoropolyprene, polyvinylidene fluoride, and the like, or a mixture thereof. As the polyolefin wax and fluororesin, those that are stably dispersed in water are used. In addition, microcrystalline, lanolin, carnauba, fatty acid, fatty acid ester, aliphatic alcohol, and other lubricating substances that are incompatible with the resin are added together with the polyolefin wax and fluororesin within a range that does not deteriorate the performance of the lubricating film. be able to.

  If the average particle diameter of the lubricant is less than 0.1 μm, the friction coefficient cannot be sufficiently reduced and the moldability cannot be satisfied. On the other hand, when the average particle size exceeds 30 μm, desorption from the lubricating film increases. The addition amount of the lubricant is 1 to 30 parts by weight with 100 parts by weight of the alkali film removal type urethane resin. If it is less than 1 part by weight, sufficient moldability cannot be obtained, and if it exceeds 30 parts by weight, the strength of the lubricating film is lowered, the adhesiveness is lowered, and the lubricant is detached.

  The water-based paint for forming the lubricating film used in the present invention includes silica, metal oxides, conductive additives, surfactants, thickeners in addition to the alkali film-removing urethane resin, water-soluble zirconium compound and lubricant. Add agents, antifoaming agents, leveling agents, dispersants, desiccants, stabilizers, anti-skinning agents, antifungal agents, antiseptics, antifreeze agents, etc., depending on the purpose within a range that does not cause deterioration in film performance. be able to. The solvent of the paint is mainly water, but for the purpose of improving the paintability, alcohol, ketone, cellosolve water-soluble organic solvent may be added as needed without impairing the performance of the lubricating film.

  Conventionally known methods such as a roll coater method, a spray method, a brush coating method, and a bar coater method can be used as a method for forming the lubricating film used in the present invention on the surface of the aluminum substrate. The blending ratio and concentration of each component in the water-based paint at the time of coating may be adjusted as appropriate in consideration of conditions such as viscosity and wettability so that the film thickness and composition of the formed film are within the above range. Good. What is necessary is just to hold | maintain drying of the coated lubricating film about 1 second-10 minutes in room temperature-250 degreeC atmosphere. Preferably, it is 5 seconds to 5 minutes. As the drying furnace, a hot air drying furnace, an induction heating furnace, an infrared furnace or the like can be used.

  In order to remove the film by removing the alkali film-removing urethane resin and the lubricant in the dried lubricating film, the lubricated coated aluminum material that has been press-molded is subjected to alkali treatment. As the alkali treatment, contact with an alkaline solution is preferably used. As the alkaline solution, an aqueous solution having a pH of 8 or higher such as sodium hydroxide or potassium hydroxide is preferably used. The film can be removed even when it is brought into contact with warm water which is inferior in efficiency but does not contain an alkali component. As the alkaline solution, a commercially available alkaline treating agent may be used. The temperature of the alkaline solution is preferably room temperature to 80 ° C. The contact time with the alkaline solution is preferably 5 seconds to 5 minutes.

  When a water-based paint containing an alkali film-removing urethane resin, a water-soluble zirconium compound and a lubricant as essential components is applied to the surface of an aluminum substrate and dried, the zirconium atoms of the water-soluble zirconium compound are first bonded via aluminum atoms and oxygen. Then, a zirconium compound layer firmly bonded to the aluminum substrate is formed. Next, the zirconium compound is chemically bonded to the functional group of the urethane resin, thereby forming a lubricating film in which the aluminum substrate, the zirconium compound, and the urethane resin are firmly and integrally bonded.

  When the lubricating coating aluminum material thus obtained is alkali-treated, only the zirconium compound bonded to the aluminum substrate remains on the substrate, and the zirconium compound reacted only with the urethane resin, the urethane resin, and the lubricant are removed. The By removing the highly insulating urethane resin and lubricant, spot welding and electrodeposition coating can be performed on the aluminum material after the alkali treatment without any problem. Further, although the details of the mechanism are unknown, the zirconium compound remaining on the aluminum substrate exhibits excellent adhesion to the coating film formed after the alkali treatment.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, a present Example is only an example and does not limit this invention.

Examples 1-20 and Comparative Examples 1-11
A JIS5082 aluminum alloy plate having a thickness of 1.0 mm was used as the aluminum substrate, and an O material was obtained by heating at 550 ° C. As a pretreatment for coating the aluminum substrate, a test material was prepared with or without the following A1 to A3 cleaning (in Comparative Example 1, such cleaning was not performed). In addition, an aqueous coating composition described in Table 1 was prepared by adding an aqueous solution of a water-soluble zirconium compound and a lubricant to emulsions of alkali film-removing urethane resins having different acid values. After coating this water-based paint on both surfaces of the test material, it was held for 40 seconds in an atmosphere at 200 ° C. and dried to prepare a sample of the lubricating film-coated aluminum material. Further, the prepared lubricating film coated aluminum material sample was immersed for 2 minutes in a 40 ° C. deteriorated degreasing solution adjusted to pH 9 by blowing carbon dioxide into a commercially available alkaline degreasing agent (sodium hydroxide type), and then washed with water. To give an alkali treatment. In this way, the alkali film-removing resin and the lubricant were removed from the lubricating film to remove the film.

Examples of the alkali film-removable urethane resin include (i) 1,3-isocyanatomethyl-3,5,5-trimethylcyclohexyl which is a compound having at least two isocyanate groups per molecule, and (ii) at least per molecule. Triethylene glycol (ii-1), which is a polyol compound having two active hydrogen groups, and a polyester polyol (ii-2) having a molecular weight of 2000 composed of adipic acid and ethylene glycol, and (iii) at least 1 in the molecule A copolymer with dimethylolpropionic acid, which is a compound having a number of active hydrogen groups and a hydrophilic group such as a carboxyl group or a sulfonic acid group, was used. In the obtained copolymer, the weight ratio of each compound of (i) to (iii) having an acid value of 15 mg-KOH / g is (i) :( ii-1) :( ii-2) :( iii) ) = 25: 5: 66: 4. When the acid value was 28 mg-KOH / g, (i) :( ii-1) :( ii-2) :( iii) = 32: 4: 57: 7. When the acid value was 70 mg-KOH / g, (i) :( ii-1) :( ii-2) :( iii) = 54: 2: 26: 18. 200 parts by weight of a 2% NaOH aqueous solution and 11% 2-[(2-aminoethyl) amino] ethanol aqueous solution are added to 100 parts by weight of the resin solid content of the urethane resin with respect to 100 parts by weight of the resin solid content of the urethane resin. 50 parts by weight were added to obtain a urethane emulsion.
Moreover, in the comparative example 11, the alkali film removal type acrylic resin was used as resin.

  As the water-soluble zirconium compound, zirconium carbonate salts shown in Table 1 were used. Zirconium carbonate was added in parts by weight shown in Table 1 in terms of metal zirconium with respect to 100 parts by weight of the alkali film-removing urethane resin. The zirconium carbonate salt was added to the paint as a 13% by weight aqueous solution (parts by weight relative to the urethane resin are metal zirconium equivalents, not parts by weight as the aqueous solution). As the lubricant, those shown in Table 1 were used. The amount of lubricant added in Table 1 is parts by weight with respect to 100 parts by weight of the alkali film-removing urethane resin. A zirconium carbonate salt and a lubricant were added to each of the urethane emulsions in the proportions shown in Table 1 to obtain an aqueous paint.

The method for cleaning the aluminum substrate is described below.
A1: 40 ° C immersion in a commercially available alkaline degreasing agent (sodium hydroxide type) for 10 seconds + 40 ° C,
Immerse in 10% nitric acid aqueous solution for 10 seconds A2: Immerse in 40% at 5 ° C, 5% sodium hydroxide aqueous solution A3: Immerse in 40% at 10 ° C in 10% nitric acid aqueous solution for 10 seconds

Aluminum substrate cleaning method and oxide film thickness; lubricant film component, film thickness, acid value, Zr equivalent, lubricant particle size and lubricant addition amount; film stability, adhesion of lubricant film before film removal, adhesion Table ¹ shows the IR maximum absorption rate (appearing on 1700 cm ^-1 unit) and residual Zr equivalent amount, electrodeposition coating properties and corrosion resistance after removal of film as properties, mold shape and processed part corrosion resistance, film removal property Shown in These measurement methods and evaluation methods are as follows.

(1) 1 g of the acid value copolymer is dissolved in 100 ml of a toluene / acetone / methanol mixed solvent (75: 12.5: 12.5) and titrated with a 1/10 N potassium hydroxide / methanol solution. From the above, the acid value was calculated.
Acid value = 5.61 × (drop amount [mg]) × (potency of drop solution) / (sample weight [g])

(2) Zr equivalent amount of lubricating film The Zr equivalent amount of the lubricating film was measured by fluorescent X-ray measurement (Rigaku Corporation, RIX-1000 type fluorescent X-ray measuring apparatus).

(3) Film stability Lubricating film coating A cellophane tape was attached to the lubricating film of the aluminum material sample, and the presence or absence of peeling powder adhered to the peeled cellophane tape was visually evaluated.
○: No adhesion of peeling powder ×: Adhesion of peeling powder ○ was accepted and x was rejected.

(4) Adhesive Lubricating Film Coating Aluminum material sample was cut into 25 mm × 150 mm, and a commercially available lubricating oil (RP-75N manufactured by Yuken Kogyo Co., Ltd.) was left standing at room temperature for 1 day after dip coating. Thereafter, a heat treatment was performed with a structural adhesive (Sunstar # 1086) with an adhesive area of 25 mm × 10 mm, an adhesive thickness of 0.2 mm, and 180 ° C. × 20 minutes to prepare an adhesive test piece. This adhesion test piece was immersed in pure water at 40 ° C. for 30 days, and then the shear peel strength was measured.
○: Shear peel strength ≧ 16 MPa
Δ: 16 MPa> shear peel strength ≧ 14 MPa
X: Shear peel strength <14 MPa
○ was accepted and Δ and × were rejected.

(5) Formability (drawability)
Lubricant coated aluminum sample is punched out into a blank, and the blank diameter is changed and deep drawing is performed with a mold with punch diameter of φ50mm and shoulder R5mm, with wrinkle suppression pressure of 600N and molding speed of 5mm / s. The drawing ratio (LDR = maximum blank diameter / punch diameter) was determined.
○: LDR ≧ 2.05
Δ: 2.05> LDR ≧ 2.00
X: LDR <2.00
○ was accepted and Δ and × were rejected.

(6) Processed part corrosion resistance 100 mm x 50 mm sample of lubricated film coated aluminum sample was used as a test piece, this was extruded 6 mm with an Erichsen test machine, and then the edge and back of the test piece were sealed with adhesive tape, 5% The salt water was sprayed for 120 hours, and the presence or absence of rusting was visually observed.
○: No rusting ×: Rusting ○ ○ was accepted and x was rejected.

(7) Lubricant-coated aluminum material sample after film-removing alkali treatment was measured for infrared absorption spectrum by high-sensitivity reflection method with a Fourier transform infrared spectroscopic analyzer, and 1700 cm ^{−1 of} which a carboxyl group absorption peak appears. The film removal property of the urethane resin was evaluated by determining the maximum absorption rate. Further, the amount of zirconium compound remaining on the surface of the aluminum substrate of the lubricant film coated aluminum material sample after film removal was measured by fluorescent X-ray analysis and determined as metal zirconium equivalent.
IR absorption rate (appears at 1700 cm ^-1 unit) ○: Absorption rate ≦ 0.5%
Δ: 0.5% <absorption rate ≦ 1%
×: Absorption rate> 1%
○ and Δ were accepted and x was rejected.
-About Zr residual amount ○: Residual amount ≧ 0.5 mg / m ²
X: Residual amount <0.5 mg / m ²
○ was accepted and x was rejected.
When both the IR absorption rate and the residual amount of Zr are acceptable, the film-removing property is accepted (O), and when one or both of the IR absorption rate and the residual amount of Zr are unacceptable, the film-removing property is rejected (× ).

(8) Electrodeposition paintability Lubricated film coated aluminum material sample was cut into 150 mm x 70 mm, the test piece was subjected to the above alkali treatment, and then electrodeposited using Saxade S # 30S (DuPont Shinto). The coating process was performed. The treatment conditions were 200 V × 3 minutes, and baking was performed at 150 ° C. for 20 minutes after electrodeposition. The appearance of the test piece after this electrodeposition coating was observed, and the presence or absence of coating omission or unevenness was visually evaluated.
○: No paint missing or unevenness ×: Paint missing or unevenness ○: acceptable, x: failed.

(9) Corrosion resistance Two 120 mm scratches were put in the test piece on which the electrodeposition coating of (8) was performed with a cutter knife so as to intersect. This test piece was subjected to four cycles of accelerated corrosion operation in which the storage for 10 days in a constant temperature and humidity chamber (40 ° C., 70% RH) after the SST 24 hour test was performed, and the maximum corrosion length generated was measured. .
○: Maximum corrosion length <1.5 mm
Δ: 1.5 mm ≧ maximum corrosion length> 2.0 mm
×: Maximum corrosion length ≧ 2.0 mm
○ was accepted and Δ and × were rejected.

In Examples 1 to 20, since the acid value and dry film thickness of the lubricating film, the IR maximum absorption rate after film removal (appearing at 1700 cm ⁻¹ ), and the residual Zr equivalent amount are within the scope of the present invention, The lubricating film performance, film removal property, and lubricating film performance after film removal were all acceptable.

In Comparative Example 1, since the cleaning for removing the oxide film was not performed, the oxide film on the aluminum substrate was too thick, causing cohesive failure, and the adhesion of the lubricating film to the aluminum substrate was poor.
In Comparative Example 2, since the lubricating film was too thin, sufficient formability of the lubricating film-coated aluminum material could not be obtained.
In Comparative Example 3, since the lubricating film was too thick, cracks occurred in the lubricating film, and the lubricant film dropped off significantly and the film stability and adhesiveness were inferior. Moreover, since the film removal property (IR maximum absorption rate) was not sufficient, the electrodeposition coating property and the corrosion resistance were inferior.
In Comparative Example 4, since the acid value of the alkali film removal type urethane resin was low, the film removal property (IR maximum absorption rate) during the alkali treatment was not sufficient. As a result, the lubricant film remained, resulting in unevenness of the electrodeposition coating film after film removal, resulting in poor electrodeposition coating properties and corrosion resistance.
In Comparative Example 5, the content of the zirconium compound in the lubricating film was small, and therefore the processed part was inferior in corrosion resistance. Since the residual amount of the zirconium compound on the surface of the aluminum substrate after film removal was too small, the film removal property was not sufficient and the corrosion resistance was inferior.
In Comparative Example 6, since the amount of the water-soluble zirconium compound in the lubricating film was too large, the lubricating film became brittle, and the film stability, adhesiveness, and moldability were inferior.
In Comparative Example 7, sufficient formability cannot be obtained because the particle size of the lubricant is too small.
In Comparative Example 8, since the particle size of the lubricant was too large, the lubricant film dropped out significantly, and the film stability, adhesiveness, and moldability were inferior.
In Comparative Example 9, sufficient formability was not obtained because the amount of lubricant added was too small.
In Comparative Example 10, since the amount of the lubricant added was too large, the strength of the lubricating film was lowered, and the film stability, adhesiveness, and moldability were inferior.
In Comparative Example 11, since an acrylic resin was used as the alkali film removal resin, the moldability of the lubricating film was not sufficient.

  The lubricating coating aluminum material according to the present invention exhibits high formability during molding. In addition, the urethane resin and lubricant are removed by the alkali treatment after molding, so there is no problem in weldability and coating after molding, and high adhesion with the coating film is also possible after painting after alkali treatment. Can be maintained. As a result, since it is excellent in corrosion resistance, it can be suitably used for various applications that require high moldability and aesthetic appearance of the product.

Claims (3)

An aluminum substrate made of an aluminum plate or an aluminum alloy plate, and a lubricating film formed on at least one surface of the aluminum substrate and having a dry film thickness of 0.05 to 10 μm, comprising an alkali film-removing urethane resin and water-soluble zirconium And a lubricant film containing a compound and a lubricant, wherein the alkali film-removing urethane resin contains a hydrophilic group, and the acid value of the hydrophilic group is 25 mg-KOH / g or more, and the surface of the aluminum substrate is 100 mm or less. The water-soluble zirconium compound is contained in the lubricating film in an amount of 1 to 50 mg / m ^{2 in} terms of metallic zirconium, and the lubricant has an average particle diameter of 0.1 to 30 μm. And 1 to 30 parts by weight with respect to 100 parts by weight of the alkali film-removing urethane resin, When removing the alkali removal membrane type urethane resin and lubricant in the lubricating layer, wherein the aluminum substrate surface, the maximum absorption rate of the peak appearing in ^-One 1700cm of FT-IR spectra in 1%, and, metal A lubricating coating aluminum material, wherein a zirconium compound layer of 0.5 mg / m ² or more in terms of zirconium remains.   The lubricating film-coated aluminum material according to claim 1, wherein the water-soluble zirconium compound is an ammonium salt or an alkali metal salt of zirconium carbonate.   The lubricating film-coated aluminum material according to claim 1 or 2, wherein the lubricant contains at least one of a polyolefin wax and a fluororesin.