Metal surface pretreatment agent

Abstract

Provided is a metal surface pre-treatment agent that can promptly form a zinc-containing film on the surface of a metal material, the metal surface pre-treatment agent moreover being such that applying a lubricant to the film yields exceptional lubricating properties.　A metal surface pre-treatment agent that is to be used in a pre-treatment for bringing a zinc-compound-containing film-forming treatment agent into contact with the surface of a metal material to form a zinc-containing film, the surface pre-treatment agent being an aqueous liquid containing an alkali component that includes at least one type from among calcium, potassium, and sodium.

Description

[Technical Field]

[0001] The present invention relates to a metal surface pretreatment agent. [Background technology]

[0002] Friction generated during plastic working, such as forging, wire drawing, pipe drawing, roll forming, and pressing of metal materials, can increase processing energy and generate heat. For this reason, various lubricants have traditionally been used in plastic working. Liquid lubricants, such as mineral oil, synthetic oil, and vegetable oil, have long been used as lubricants. However, although these lubricants can be applied to relatively simple plastic working, their lubricating performance is insufficient for plastic working, which involves sliding under high surface pressure and generates a large amount of heat.

[0003] Therefore, in plastic processing that involves the generation of large amounts of heat, a method is widely adopted in which a solid film is formed on the surface of the metal material to prevent direct contact between the processing tool, such as a mold, and the metal material being processed.

[0004] One method widely used to form solid coatings to improve the workability of metal materials is to apply a lubricating coating (aluminum zinc fluoride treatment) to the surface of aluminum to prevent material fluidity and surface seizure during processing. Specifically, an aqueous solution of zinc fluoride (ZnF2) and sodium silicofluoride is used to form a coating of aluminum fluoride and zinc fluoride on the aluminum surface, and this zinc compound is combined with soap, a lubricant, to create a coating (metallic soap), ensuring surface lubricity.

[0005] However, as the reaction progresses, aluminum ions accumulate in the coating solution, inhibiting the reaction, making it essential to frequently replace the solution. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 062360 Summary of the Invention [Problem to be solved by the invention]

[0007] For example, Patent Document 1 discloses a method for forming a clay film (layered double hydroxide) on an aluminum surface using an aqueous solution of a zinc compound. This clay film is a clay substance with a layered structure whose main components are zinc hydroxide and aluminum hydroxide, and is formed by a simple process of simply immersing aluminum in an aqueous zinc solution.

[0008] For this reason, the method for synthesizing a clay film disclosed in Patent Document 1 (clay method) can be said to be replaceable with the currently existing method of aluminum zinc fluoride treatment. Furthermore, since the clay film contains zinc hydroxide, which binds strongly to soap, a lubricant, it is possible to form a lubricating film on the aluminum surface. Another advantage of this clay method is that, unlike the aluminum zinc fluoride treatment method, aluminum does not accumulate in the film treatment solution, eliminating the need for frequent replacement of the treatment solution. Another advantage is that it does not require the use of fluorine, a harmful substance, as in the aforementioned aluminum zinc fluoride treatment.

[0009] However, the clayification method of Patent Document 1 requires a reaction time of 24 hours or more, which poses a problem for practical application. In addition, the clayification film formed by the clayification method of Patent Document 1 and the lubricant (soap) form a composite film, but it is also desired to further improve the lubricity of the composite film.

[0010] In light of these circumstances, the present invention has as its main object the provision of a metal surface pretreatment agent that can rapidly form a zinc-containing coating on the surface of a metal material and, further, that exhibits excellent lubricity by applying a lubricant to the coating. Another object of the present invention is to provide a metal surface treatment kit, a metal processing kit, a metal surface treatment method, and a metal processing method that utilize the metal surface pretreatment agent. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that by pretreating the surface of a metal material using an aqueous liquid containing an alkaline component including at least one of calcium, potassium, and sodium as a metal surface pretreatment agent, and then contacting (adhering) the metal material surface with a film-forming treatment agent containing a zinc compound after the pretreatment, a zinc-containing film can be rapidly formed on the metal material surface, and by applying a lubricant to the film, the metal material surface can exhibit excellent lubricity during plastic working of the metal material. The present invention was completed based on these findings and through further research.

[0012] That is, the present invention provides the following aspects of the invention. Item 1. A pretreatment agent used before a treatment for forming a zinc-containing film by contacting a metal material surface with a film-forming treatment agent containing a zinc compound, The pretreatment agent is an aqueous liquid containing an alkaline component including at least one of calcium, potassium, and sodium. Item 2. The metal surface pretreatment agent according to Item 1, wherein the coating does not contain fluorine atoms. Item 3. The metal surface pretreatment agent according to Item 1 or 2, wherein the metal surface pretreatment agent contains at least one of calcium hydroxide, potassium hydroxide, and sodium hydroxide as the alkaline component. Item 4. The metal surface pretreatment agent according to any one of Items 1 to 3, wherein the concentration of the alkaline component is 0.01 to 10 mol / L. Item 5. The metal surface pretreatment agent according to any one of Items 1 to 4, wherein the metal material surface is made of aluminum, zinc, magnesium, iron, copper, or an alloy containing at least one of these metals. Item 6. A first agent comprising the metal surface pretreatment agent according to any one of Items 1 to 5; a second agent comprising a film-forming treatment agent containing a zinc compound; A metal surface treatment kit comprising: Item 7. The metal surface treatment kit according to Item 6, wherein the film-forming treatment agent is an aqueous solution containing zinc nitrate. Item 8. A first agent comprising the metal surface pretreatment agent according to any one of Items 1 to 5; a second agent comprising a film-forming treatment agent containing a zinc compound; a third agent comprising a lubricant; A metal processing kit comprising: Item 9. A metal surface treatment method comprising a pretreatment step of contacting the metal surface pretreatment agent according to any one of Items 1 to 5 with a metal material surface. Item 10. A film formation treatment method comprising, after the pretreatment step of the metal surface treatment method according to Item 9, a film formation step of contacting the metal material surface to which the metal surface pretreatment agent has adhered with a film-forming treatment agent containing a zinc compound. Item 11. A pretreatment step of contacting a metal surface pretreatment agent according to any one of Items 1 to 5 with a metal material surface; a film-forming step of contacting the metal surface, which has been contacted with the metal surface pretreatment agent, with a film-forming treatment agent containing a zinc compound after the pretreatment step; a lubrication treatment step of bringing a lubricant into contact with the surface of the metal material on which the zinc-containing coating has been formed by the coating formation step; a metal working step of subjecting the metal material to plastic working after the lubrication treatment step; A metal processing method comprising: [Effects of the Invention]

[0013] By pretreating the surface of a metal material using the metal surface pretreatment agent of the present invention, a zinc-containing coating can be rapidly formed on the pretreated metal material surface, and by applying a lubricant to the coating, excellent lubricity can be exhibited.Furthermore, according to the present invention, it is also possible to provide a metal surface treatment kit, a metal working kit, a metal surface treatment method, and a metal working method that utilize the metal surface pretreatment agent. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1. Metal surface pretreatment agent The metal surface pretreatment agent of the present invention is a pretreatment agent used before a treatment in which a film-forming treatment agent containing a zinc compound is contacted (adhered) to the surface of a metal material to form a zinc-containing film, and is characterized by being an aqueous liquid containing an alkaline component containing at least one of calcium, potassium, and sodium. Because the metal surface pretreatment agent of the present invention has this configuration, a zinc-containing film is rapidly formed by contacting (adhering) the film-forming treatment agent containing a zinc compound to the pretreated metal material surface. Furthermore, by applying a lubricant to the film, the metal material surface exhibits excellent lubricity during plastic working of the metal material. Metal materials with enhanced lubricity have excellent plastic workability. The metal surface pretreatment agent of the present invention is described in detail below.

[0015] In the metal surface pretreatment agent of the present invention, the aqueous liquid containing an alkaline component containing at least one of calcium, potassium, and sodium is specifically an aqueous suspension or solution containing an alkaline component containing at least one of calcium, potassium, and sodium. That is, the metal surface pretreatment agent of the present invention may be in the form of an aqueous suspension or an aqueous solution. From the viewpoint of more suitably exhibiting the effects of the present invention, the metal surface pretreatment agent of the present invention is preferably in the form of an aqueous suspension. In particular, when the alkaline component is calcium, the metal surface pretreatment agent of the present invention is preferably in the form of an aqueous suspension.

[0016] The metal surface pretreatment agent of the present invention is a pretreatment agent that is brought into contact with (adhered to) the surface of a metal material and used for surface treatment of the metal material. When a film-forming treatment agent containing a zinc compound is brought into contact with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, a zinc-containing film is suitably formed. That is, at least one of calcium, potassium, and sodium contained in the metal surface pretreatment agent adhered to the metal surface is rapidly substituted for the zinc contained in the film-forming treatment agent, and a zinc-containing film is suitably formed on the metal material surface. The metal material on whose surface a zinc-containing film has been formed can then be coated with a lubricant and suitably subjected to plastic working.

[0017] The metal surface pretreatment agent of the present invention is an aqueous liquid containing an alkaline component containing at least one of calcium, potassium, and sodium. The alkaline component is preferably calcium hydroxide (Ca(OH)2), potassium hydroxide (KOH), sodium hydroxide (NaOH), etc., with calcium hydroxide (Ca(OH)2) being particularly preferred. That is, the metal surface pretreatment agent of the present invention is preferably at least one of an aqueous calcium hydroxide liquid, a potassium hydroxide, and a sodium hydroxide aqueous liquid, with an aqueous calcium hydroxide liquid being particularly preferred. The aqueous calcium hydroxide liquid is particularly preferably a calcium hydroxide aqueous suspension.

[0018] In the metal surface pretreatment agent of the present invention, the concentration of the alkaline component is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing coating on the surface of the metal material after pretreatment, it is preferably about 0.01 to 10 mol / L, more preferably about 0.03 to 5 mol / L, and even more preferably about 0.05 to 1 mol / L.

[0019] The temperature at which the metal surface pretreatment agent of the present invention is brought into contact with (adhered to) the surface of a metal material to pretreat the metal surface is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing coating on the surface of the metal material after pretreatment, the temperature is preferably about 20 to 90°C, more preferably about 30 to 80°C, even more preferably about 40 to 80°C, and particularly preferably about 60 to 80°C.

[0020] The time for which the metal surface pretreatment agent of the present invention is brought into contact with the surface of a metal material is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing coating on the surface of the metal material after pretreatment, it is preferably 1 hour or less, more preferably 30 minutes or less, even more preferably 20 minutes or less, and particularly preferably 10 minutes or less. The lower limit of the time for which the metal surface pretreatment agent of the present invention is brought into contact with the surface of a metal material is preferably 30 seconds or more, more preferably 1 minute or more.

[0021] The method for contacting (adhering) the metal surface pretreatment agent of the present invention with the surface of a metal material is not particularly limited, and can be performed by known methods such as roll coating, spin coating, spraying, and immersion.

[0022] It is preferable to clean the surface of the metal material before contacting (adhering) the metal surface pretreatment agent of the present invention to the surface of the metal material. The main purpose of cleaning the surface of the metal material is to remove various contaminants (oil, etc.) adhering to the surface of the metal material. There are no particular limitations on the method for cleaning the surface of the metal material, but methods using known cleaning agents such as alkaline degreasing agents and acidic degreasing agents can be used. It is also preferable to perform water rinsing during cleaning.

[0023] The film-forming treatment agent containing a zinc compound is not particularly limited as long as it contacts (adheres to) the surface of a metal material to form a zinc-containing film, and known film-forming treatment agents used in the plastic processing of metal materials can be used. The zinc compound is not particularly limited as long as it is water-soluble, but zinc nitrate, zinc sulfate, zinc chloride, etc. are preferred, with zinc nitrate being particularly preferred. The zinc compound contained in the film-forming treatment agent may be one type or two or more types. Examples of zinc-containing films include layers formed from clay substances with a layered structure (clay films of layered double hydroxides) primarily composed of zinc hydroxide and aluminum hydroxide, as described in Patent Document 1.

[0024] Specific examples of the film-forming treatment agent containing a zinc compound include an aqueous solution of zinc nitrate, an aqueous solution of zinc sulfate, an aqueous solution of zinc chloride, etc., with an aqueous solution of zinc nitrate being particularly preferred.

[0025] The zinc-containing coating formed on the metal material preferably does not contain fluorine atoms, i.e., the coating-forming treatment agent containing a zinc compound preferably does not contain any component containing fluorine atoms.

[0026] In the film-forming treatment agent containing a zinc compound, the concentration of the zinc compound is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing film by contacting (adhering) the zinc compound to the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, the concentration is preferably about 0.05 to 10 mol / L, more preferably about 0.08 to 5 mol / L, and even more preferably about 0.1 to 1 mol / L.

[0027] The pH of the zinc compound-containing film-forming treatment agent is not particularly limited, but is preferably about 5 to 7, more preferably about 5.5 to 6.5, from the viewpoint of particularly rapid formation of a zinc-containing film upon contact (adhesion) with the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention. To achieve an acidic pH of about 5.5 to 6.5, for example, aqueous ammonia or the like may be added to the film-forming treatment agent.

[0028] Furthermore, the temperature at which a film-forming treatment agent containing a zinc compound is brought into contact with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention to form a zinc film on the metal surface is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing film by contacting (adhering) the treatment agent with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, the temperature is preferably about 30 to 100°C, more preferably about 40 to 90°C, even more preferably about 60 to 85°C, and particularly preferably about 65 to 85°C.

[0029] The time for which the film-forming treatment agent containing a zinc compound is brought into contact with the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention is not particularly limited, but from the viewpoint of particularly rapid formation of a zinc-containing film by contact with the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, it is preferably 1 hour or less, more preferably 30 minutes or less, even more preferably 20 minutes or less, and particularly preferably 10 minutes or less. The lower limit of the time for which the metal surface pretreatment agent of the present invention is brought into contact with the surface of a metal material is preferably 30 seconds or more, more preferably 1 minute or more.

[0030] The method for contacting (adhering) the film-forming treatment agent containing a zinc compound with (to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention is not particularly limited, and can be, for example, a known method such as roll coating, spin coating, spraying, or immersion.

[0031] In the metal material to be treated with the metal surface pretreatment agent of the present invention, the metal constituting the metal material is preferably aluminum, zinc, magnesium, iron, copper, or an alloy containing at least one of these metals, with aluminum being particularly preferred. That is, the surface of the metal material to be treated with the metal surface pretreatment agent of the present invention is preferably composed of aluminum, zinc, magnesium, iron, copper, or an alloy containing at least one of these metals, and particularly preferably composed of aluminum.

[0032] Metal materials with a zinc-containing coating formed thereon can be subjected to plastic working after lubrication treatment. Known lubrication treatment methods used in the plastic working of metal materials can be used as the lubrication treatment method. In the lubrication treatment of metal materials, lubricants containing solid lubricants such as molybdenum disulfide and graphite, as well as oils and soaps, are widely used. Soaps are preferably used as lubricants because they combine with zinc to form metallic soaps, which bind strongly and reduce viscosity due to heat generated during plastic working, improving lubricity. Soaps and oils that do not combine with zinc are also effective for lubrication. Only one type of lubricant component may be used, or two or more types may be mixed together.

[0033] Examples of oils include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; unsaturated fatty acids such as palmitoleic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid; and fatty acids having about 12 to 26 carbon atoms, such as branched fatty acids. Examples of soaps include alkali metal salts of fatty acids having about 12 to 26 carbon atoms (saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; unsaturated fatty acids such as palmitoleic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid; branched fatty acids); and metallic soaps obtained by reacting fatty acids having 12 to 26 carbon atoms (saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid; unsaturated fatty acids such as palmitoleic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid; branched fatty acids); with at least one metal selected from zinc, calcium, barium, aluminum, and magnesium.

[0034] The lubricant can be used in the form of an aqueous solution of the lubricant components. The concentration of the lubricant components in the aqueous solution is not particularly limited as long as a predetermined amount of the lubricant components adheres to the metal material, but may be, for example, about 0.5 to 10 mass %.

[0035] The temperature in the lubrication treatment is not particularly limited, and known lubrication treatment conditions for metal material surfaces can be used, for example, about 30 to 100°C, preferably about 40 to 90°C, and more preferably about 60 to 90°C.

[0036] 2. Metal surface treatment kit The metal surface treatment kit of the present invention is characterized by comprising a first agent comprising the metal surface pretreatment agent of the present invention described above, and a second agent comprising the film-forming treatment agent containing the zinc compound described above.

[0037] Using the metal surface treatment kit of the present invention, a metal material surface is pretreated with a first agent comprising the metal surface pretreatment agent of the present invention described above, and then the pretreated metal material surface is surface-treated with a second agent comprising a film-forming treatment agent containing a zinc compound, thereby making it possible to suitably form a zinc-containing film on the metal material surface. Furthermore, by adhering a lubricant to the film and subjecting the metal material to plastic working, the metal material surface exhibits excellent lubricity during plastic working. Metal materials with enhanced lubricity have excellent plastic workability.

[0038] Details of the metal surface pretreatment agent, the film-forming treatment agent containing a zinc compound, and the lubricant of the present invention are as described above. The details of the metal material are as described in the section "1. Metal surface treatment agent."

[0039] 3. Metalworking kit The metalworking kit of the present invention comprises a first agent comprising the metal surface pretreatment agent of the present invention described above, a second agent comprising the film-forming treatment agent containing the zinc compound described above, and a third agent comprising a lubricant.

[0040] Using the metalworking kit of the present invention, the surface of a metal material is pretreated with a first agent consisting of the metal surface pretreatment agent of the present invention described above, followed by surface treatment of the pretreated metal material surface with a second agent consisting of a film-forming treatment agent containing a zinc compound, and then lubrication treatment with a third agent consisting of a lubricant, thereby providing the metal material surface with excellent lubricity during plastic working of the metal material. Metal materials with improved lubricity have excellent plastic workability.

[0041] Details of the metal surface pretreatment agent, the film-forming treatment agent containing a zinc compound, and the lubricant of the present invention are as described above. The details of the metal material are as described in the section "1. Metal surface treatment agent."

[0042] 4.Metal surface treatment methods The metal surface treatment method of the present invention comprises a pretreatment step of contacting (adhering) the metal surface pretreatment agent of the present invention to the surface of a metal material.

[0043] As described above, when a film-forming treatment agent containing a zinc compound is brought into contact with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, a film containing zinc is suitably formed.The metal material on whose surface a film containing zinc has been formed can then be suitably subjected to plastic working by applying a lubricant thereto.

[0044] Details of the metal surface pretreatment agent of the present invention are as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., when the metal surface pretreatment agent of the present invention is brought into contact with (adhered to) the surface of a metal material to pretreat the metal surface are also as described in the section "1. Metal surface treatment agent." The metal material is also as described in the section "1. Metal surface treatment agent."

[0045] 5. Film formation treatment method The film formation treatment method of the present invention includes a film formation step in which, after the pretreatment step of the metal surface treatment method of the present invention described in the section "4. Metal surface treatment method," a film formation treatment agent containing a zinc compound is brought into contact with (deposited on) the metal material surface to which the metal surface pretreatment agent has been attached.

[0046] As described above, when a film-forming treatment agent containing a zinc compound is brought into contact with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, a film containing zinc is suitably formed.The metal material on whose surface a film containing zinc has been formed can then be suitably subjected to plastic working by applying a lubricant thereto.

[0047] Details of the metal surface pretreatment agent and film-forming treatment agent of the present invention are as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., used when the metal surface pretreatment agent of the present invention is brought into contact with the surface of a metal material to pretreat the metal surface are also as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., used when the film-forming treatment agent containing a zinc compound is brought into contact with the surface of a metal material that has been contacted with the metal surface pretreatment agent of the present invention are also as described in the section "1. Metal surface treatment agent." The metal material is also as described in the section "1. Metal surface treatment agent."

[0048] 6.Metal processing method The metal processing method of the present invention includes a pretreatment step of contacting (adhering) the metal surface pretreatment agent of the present invention to the surface of a metal material, a film formation step of contacting (adhering) a film-forming treatment agent containing a zinc compound to the surface of the metal material that has been contacted (adhered) with the metal surface pretreatment agent after the pretreatment step, a lubrication step of contacting a lubricant with the surface of the metal material on which a zinc-containing film has been formed by the film formation step, and a metal processing step of subjecting the metal material to plastic processing after the lubrication step.

[0049] As described above, when a film-forming treatment agent containing a zinc compound is brought into contact with (adhered to) the surface of a metal material that has been surface-treated with the metal surface pretreatment agent of the present invention, a film containing zinc is suitably formed.The metal material on whose surface a film containing zinc has been formed can then be suitably subjected to plastic working by applying a lubricant thereto.

[0050] Details of the metal surface pretreatment agent, film-forming treatment agent, and lubricant of the present invention are as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., when the metal surface pretreatment agent of the present invention is brought into contact with the surface of a metal material to pretreat the metal surface are also as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., when a film-forming treatment agent containing a zinc compound is brought into contact with the surface of a metal material that has been brought into contact with the metal surface pretreatment agent of the present invention are also as described in the section "1. Metal surface treatment agent." The temperature, time, method, etc., when a lubricant is brought into contact with the surface of a metal material on which a zinc-containing film has been formed are also as described in the section "1. Metal surface treatment agent." The metal material is also as described in the section "1. Metal surface treatment agent." [Example]

[0051] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0052] [Examples 1 to 14 and Comparative Example 2] 1. Preparation of treatment agent The metal surface pretreatment agent, film-forming treatment agent, and lubricant were each prepared as follows: In Comparative Example 1, as described below, the surface of the metal material was treated using a 3% aqueous solution of "Ferrolube No. 1" manufactured by Kiwa Chemical Industries, Ltd.

[0053] <Metal surface pretreatment agent> The alkali component was commercially available calcium hydroxide in Examples 1 to 12, commercially available potassium hydroxide in Example 13, commercially available sodium hydroxide in Example 14, and commercially available magnesium hydroxide in Comparative Example 2. Each alkali component was dispersed or dissolved in water to the concentration (M = mol / L) shown in the "Metal surface pretreatment agent" column in Table 1 to obtain a metal surface pretreatment agent. In Examples 1 to 8, 11 to 12, and Comparative Example 2, the metal surface pretreatment agent was an aqueous suspension. In Examples 9 to 10 and 13 to 14, the metal surface pretreatment agent was an aqueous solution.

[0054] <Film-forming treatment agent> The film-forming treatment agent was prepared by dissolving commercially available zinc nitrate hexahydrate in water to the concentration (M = mol / L) shown in the "Film-forming treatment agent" column in Table 1, and adjusting the pH to 6 with ammonium water.

[0055] <Lubricant> An aqueous solution containing the lubricant components shown in the "lubricant" column of Table 1 at a concentration of 3 mass % was used as the lubricant.

[0056] 2. Surface treatment of metal materials <Pretreatment process> Aluminum materials (A5052 (ring), A5056 (cylinder), and A6061 (cylinder), each of which was used in the tests described below) were treated with a 3% aqueous solution of "Alkylene F700K," a degreasing agent manufactured by Kiwa Chemical Co., Ltd., and then rinsed with water. They were then immersed in a chemical polishing solution to condition the metal surface, and then rinsed with water. The aluminum materials were then immersed in each of the metal surface pretreatment agents listed in Table 1 at 70°C for 6 minutes, after which they were rinsed with water.

[0057] <Film formation process> After the pretreatment step, each aluminum material was immersed in each film-forming treatment solution at the temperature and for the time specified in the "Film-forming treatment solution" column in Table 1, and a film containing zinc hydroxide (clay film of layered double hydroxide) was formed on the surface of the aluminum material through an ion exchange reaction with the alkaline component attached in the pretreatment step.

[0058] <Lubrication process> Each lubricant was applied to the surface of the aluminum material that had been subjected to the film forming process, and then dried at the temperature shown in Table 1 to adhere the lubricant to the surface of the aluminum material.

[0059] [Comparative Example 1] In Comparative Example 1, an aluminum material was treated with an aluminum zinc fluoride process to form a coating of a metal surface pretreatment agent on its surface, and then the material was lubricated using a 3% aqueous solution of "Ferroluebe No. 1" manufactured by Kiwa Chemical Industries, Ltd. The lubricating film was dried at room temperature to obtain an aluminum material coated with a lubricant.

[0060] 3. Evaluation of plastic workability of metal materials The aluminum materials to which lubricants were applied obtained in Examples 1 to 14 and Comparative Examples 1 and 2 were subjected to the following link compression test, upsetting test, and backward extrusion test to evaluate the plastic workability of the metal material. The results are shown in Table 2.

[0061] <Ring compression test> The rings used in the ring compression test were made of aluminum A5052, with an outer diameter of 21.0 mm, an inner diameter of 10.5 mm, and a thickness of 7.0 mm. In the examples and comparative examples, each lubricated aluminum ring was pressed under a load of 200 tons at a compression ratio of 60%. The thickness and inner diameter of the compressed ring were measured, and the friction coefficient was determined. Each ring compression test was performed three times, and the average friction coefficient μ was calculated. The relationship between the shape of the compressed ring and the friction coefficient during ring compression testing is known. When the friction coefficient is small, both the inner and outer diameters are compressed so that they bulge outward. When the friction coefficient is large, the inner diameter bulges inward, and the outer diameter bulges outward only slightly. Therefore, the dimensional change of the inner diameter can be measured and the friction coefficient can be calculated. The lower the friction coefficient, the better the lubrication performance.

[0062] <Upset test> The cylindrical test specimens used in the upsetting test were aluminum A5056, with a diameter of 40.0 mm and a height of 52.0 mm. In the examples and comparative examples, each cylindrical test specimen made of aluminum material with a lubricant applied was pressed under a load of 200 tons at a compression rate of 30%. After compression, the amount of lubricant peeled off from the test specimen was measured. Each upsetting test was performed three times, and the average amount of peeled off was calculated. The amount of lubricant attached to the test specimen before and after compression was measured, and the amount of lubricant peeled off can be calculated from the difference in the amount of lubricant attached to the test specimen before and after compression.

[0063] <Backward extrusion test> The cylindrical test pieces used in the backward extrusion test were aluminum A5056 and aluminum A6061, each with a diameter of 29.9 mm and a height of 24.0 mm. The backward extrusion friction test was performed as follows. First, each cylindrical test piece made of aluminum material with a lubricant applied thereto in the examples and comparative examples was inserted into a mold and pressed under a load of 200 tons at a compression rate of 20%. The appearance of the test pieces after backward extrusion was observed and evaluated according to the following criteria. ○: No burn-in ×: Burning occurs

[0064] [Table 1]

[0065] [Table 2]

Claims

1. A metal surface pretreatment agent used before a treatment for forming a zinc-containing coating by contacting a metal material surface with a coating-forming treatment agent containing a zinc compound, comprising: the metal surface pretreatment agent is an aqueous liquid containing an alkaline component including at least one of calcium, potassium, and sodium; the metal material surface is made of an alloy containing aluminum, the zinc compound includes zinc nitrate; the coating is a clay film of a layered double hydroxide containing zinc hydroxide and aluminum hydroxide, The metal surface pretreatment agent contains calcium hydroxide as the alkaline component.

2. The metal surface pretreatment agent according to claim 1 , wherein the coating does not contain fluorine atoms.

3. 3. The metal surface pretreatment agent according to claim 1, wherein the concentration of the alkaline component is 0.01 to 10 mol / L.

4. A first agent comprising the metal surface pretreatment agent according to any one of claims 1 to 3; a second agent comprising a film-forming treatment agent containing a zinc compound; A metal surface treatment kit comprising: the metal material surface is made of an alloy containing aluminum, the coating is a clay film of a layered double hydroxide containing zinc hydroxide and aluminum hydroxide, The metal surface pretreatment agent contains calcium hydroxide as the alkaline component, The metal surface treatment kit, wherein the film-forming treatment agent is an aqueous solution containing zinc nitrate.

5. A first agent comprising the metal surface pretreatment agent according to any one of claims 1 to 3; a second agent comprising a film-forming treatment agent containing a zinc compound; a third agent comprising a lubricant; A metalworking kit comprising: the metal material surface is made of an alloy containing aluminum, the coating is a clay film of a layered double hydroxide containing zinc hydroxide and aluminum hydroxide, The metal surface pretreatment agent contains calcium hydroxide as the alkaline component, The metalworking kit, wherein the film-forming treatment agent is an aqueous solution containing zinc nitrate.

6. A metal surface treatment method comprising a pretreatment step of contacting a metal material surface with the metal surface pretreatment agent according to any one of claims 1 to 3, the metal material surface is made of an alloy containing aluminum, the zinc compound includes zinc nitrate; the coating is a clay film of a layered double hydroxide containing zinc hydroxide and aluminum hydroxide, The metal surface treatment method, wherein the metal surface pretreatment agent contains calcium hydroxide as the alkaline component.

7. The metal surface treatment method according to claim 6 further comprises, after the pretreatment step, a film-forming step of contacting the metal material surface to which the metal surface pretreatment agent has adhered with a film-forming treatment agent containing a zinc compound, The coating formation treatment method, wherein the coating formation treatment agent is an aqueous solution containing zinc nitrate.

8. a pretreatment step of contacting the metal surface pretreatment agent according to any one of claims 1 to 3 with a metal material surface; a film-forming step of contacting the metal surface, which has been contacted with the metal surface pretreatment agent, with a film-forming treatment agent containing a zinc compound after the pretreatment step; a lubrication treatment step of bringing a lubricant into contact with the surface of the metal material on which the zinc-containing coating has been formed by the coating formation step; a metal working step of subjecting the metal material to plastic working after the lubrication treatment step; A metal processing method comprising: the metal material surface is made of an alloy containing aluminum, the coating is a clay film of a layered double hydroxide containing zinc hydroxide and aluminum hydroxide, The metal surface pretreatment agent contains calcium hydroxide as the alkaline component, A metal processing method, wherein the film-forming treatment agent is an aqueous solution containing zinc nitrate.

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