JP7727282B2 - Metal surface pretreatment agent - Google Patents

Description

The present invention relates to a metal surface pretreatment agent.

Friction that occurs during plastic processing 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 processing. Liquid lubricants such as mineral oil, synthetic oil, and vegetable oil have long been used. However, while these lubricants are applicable to relatively simple plastic processing, their lubricating performance is insufficient for plastic processing that involves sliding under high surface pressure and generates a large amount of heat.

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.

As a method for forming a solid film to improve the workability of metal materials, for example, in the case of aluminum, a lubricating film chemical conversion treatment (aluminum zinc fluoride treatment) is widely used to fluidize the material during processing and prevent the material surface from seizing. Specifically, an aqueous solution of zinc fluoride ( _ZnF2 ) and sodium silicofluoride is used to form a film of aluminum fluoride and zinc fluoride on the aluminum surface, and this zinc compound is combined with soap, a lubricant, to create a film (metal soap), thereby ensuring surface lubricity.

However, as the reaction progresses, aluminum ions accumulate in the coating solution, inhibiting the reaction, making it essential to frequently replace the solution.

International Publication No. 2018/062360

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 the aluminum in an aqueous zinc solution.

For this reason, the clay film synthesis method (clay method) disclosed in Patent Document 1 can be said to be a replacement for the currently existing aluminum zinc fluoride treatment method. Furthermore, because 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 aluminum zinc fluoride treatment described above.

However, the clayification method described in Patent Document 1 requires a reaction time of 24 hours or more, posing challenges to its practical application. Furthermore, the clayification film formed by the clayification method described in Patent Document 1 and the lubricant (soap) form a composite film, but there is also a need to further enhance the lubricity of this composite film.

In light of these circumstances, the primary objective of the present invention is to provide a metal surface pretreatment agent that can rapidly form a zinc-containing coating on the surface of a metal material, and that, when a lubricant is applied to the coating, exhibits excellent lubricity. A further objective 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.

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

That is, the present invention provides the following aspects of the invention.
Item 1. A pretreatment agent used before a treatment in which a film-forming treatment agent containing a zinc compound is brought into contact with a metal material surface to form a film containing zinc,
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 a metal surface with the metal surface pretreatment agent according to any one of Items 1 to 5.
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:

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 surface. Furthermore, by applying a lubricant to this coating, a metal surface pretreatment agent can be provided that exhibits excellent lubricity. Furthermore, the present invention can also provide a metal surface treatment kit, a metal processing kit, a metal surface treatment method, and a metal processing method that utilize this metal surface pretreatment agent.

1. Metal Surface Pretreatment Agent The metal surface pretreatment agent of the present invention is a pretreatment agent used before contacting (adhering) a film-forming treatment agent containing a zinc compound to a metal material surface to form a zinc-containing film, and is characterized by being an aqueous liquid containing an alkaline component including at least one of calcium, potassium, and sodium. Because the metal surface pretreatment agent of the present invention has this configuration, contacting (adhering) the film-forming treatment agent containing a zinc compound to (adhering) the pretreated metal material surface quickly forms a zinc-containing film. Furthermore, applying a lubricant to this film provides the metal material surface with 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.

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 perspective of more optimally 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.

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 to treat the surface 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 using 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 quickly 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 with a zinc-containing film formed on its surface can then be coated with a lubricant and suitably subjected to plastic working.

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.

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 quickly forming a zinc-containing coating on the surface of the metal material after pretreatment, it is preferably approximately 0.01 to 10 mol/L, more preferably approximately 0.03 to 5 mol/L, and even more preferably approximately 0.05 to 1 mol/L.

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 quickly forming a zinc-containing coating on the surface of the metal material after pretreatment, it 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.

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.

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

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.) that have adhered to the surface of the metal material. There are no particular restrictions on the method for cleaning the surface of the metal material, but methods using known cleaning agents such as alkaline degreasers and acidic degreasers can be used. It is also preferable to rinse with water during cleaning.

There are no particular restrictions on the film-forming treatment agent containing a zinc compound, as long as it contacts (adheres to) the surface of a metal material to form a zinc-containing film. 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 film-forming treatment agent may contain one type of zinc compound 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.

Specific examples of coating-forming treatment agents containing zinc compounds include aqueous solutions of zinc nitrate, zinc sulfate, and zinc chloride, with aqueous solutions of zinc nitrate being particularly preferred.

It is preferable that the zinc-containing coating formed on the metal material does not contain fluorine atoms. In other words, it is preferable that the coating-forming treatment agent containing a zinc compound does not contain any components containing fluorine atoms.

In a film-forming treatment agent containing a zinc compound, the concentration of the zinc compound is not particularly limited, but from the perspective of particularly rapidly forming a zinc-containing film by contacting (adhering) the zinc compound with 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 approximately 0.05 to 10 mol/L, more preferably approximately 0.08 to 5 mol/L, and even more preferably approximately 0.1 to 1 mol/L.

The pH of the film-forming treatment agent containing a zinc compound is not particularly limited, but is preferably about 5 to 7, and more preferably about 5.5 to 6.5, from the perspective 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, it is advisable to add ammonia water or the like to the film-forming treatment agent.

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 perspective of particularly rapidly forming a zinc-containing film by contacting (adhering) 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 approximately 30 to 100°C, more preferably approximately 40 to 90°C, even more preferably approximately 60 to 85°C, and particularly preferably approximately 65 to 85°C.

There are no particular restrictions on the time for which a 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. However, from the perspective of particularly rapidly forming 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, the time 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. Furthermore, 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.

The method for contacting (adhering) a film-forming treatment agent containing a zinc compound 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, but can be carried out by known methods such as roll coating, spin coating, spraying, and immersion.

In the metal materials to be treated with the metal surface pretreatment agent of the present invention, the metals constituting the metal materials are preferably aluminum, zinc, magnesium, iron, copper, or alloys containing at least one of these metals, with aluminum being particularly preferred. In other words, the metal material surfaces to be treated with the metal surface pretreatment agent of the present invention are preferably composed of aluminum, zinc, magnesium, iron, copper, or alloys containing at least one of these metals, with aluminum being particularly preferred.

Metal materials bearing a zinc-containing coating can be subjected to plastic processing after lubrication. Lubrication methods commonly used in the plastic processing of metal materials can be used. In lubricating metal materials, lubricants containing solid lubricants such as molybdenum disulfide and graphite, as well as oil and soap, are widely used. Soap is preferred as a lubricant because it bonds strongly with zinc to form metallic soap, which reduces viscosity due to heat generated during plastic processing, improving lubrication. Soap and oil that do not bond with zinc are also effective for lubrication. A single lubricant component may be used, or two or more may be mixed together.

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 with approximately 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, etc.), or 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, etc.) with at least one metal selected from zinc, calcium, barium, aluminum, and magnesium.

The lubricant can be used in the form of an aqueous solution of the lubricant components described above. 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 examples include approximately 0.5 to 10% by mass.

The temperature for lubrication treatment is not particularly limited, and known lubrication treatment conditions for metal material surfaces can be adopted, for example, approximately 30 to 100°C, preferably approximately 40 to 90°C, and more preferably approximately 60 to 90°C.

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.

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 successfully forming a zinc-containing film on the metal material surface. Furthermore, by adhering a lubricant to the film and subjecting the metal material to plastic processing, the metal material surface exhibits excellent lubricity during plastic processing. Metal materials with enhanced lubricity have excellent plastic processability.

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

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.

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. This allows the metal material surface to exhibit excellent lubricity during plastic working of the metal material. Metal materials with enhanced lubricity have excellent plastic workability.

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

4. Metal Surface Treatment Method 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 (on) the surface of a metal material.

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

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, and method for pretreating a metal surface by contacting (adhering) the metal surface pretreatment agent of the present invention to the surface of a metal material 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."

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 adhered.

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

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, and method for pretreating a metal surface by contacting the metal surface pretreatment agent of the present invention with the surface of a metal material are also as described in the section "1. Metal Surface Treatment Agent." The temperature, time, and method for contacting a film-forming treatment agent containing a zinc compound 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."

6. Metalworking Method The metalworking method of the present invention comprises a pretreatment step of contacting (adhering) the metal surface pretreatment agent of the present invention described above with (to) the surface of a metal material, a coating step of contacting (adhering) a coating forming agent containing a zinc compound with (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, with a lubricant, the surface of the metal material on which a zinc-containing coating has been formed by the coating step, and a metalworking step of subjecting the metal material to plastic working after the lubrication step.

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

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, and method for pretreating a metal surface by contacting the metal surface pretreatment agent of the present invention with the surface of a metal material are also as described in the section "1. Metal Surface Treatment Agent." The temperature, time, and method for contacting a film-forming treatment agent containing a zinc compound 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 temperature, time, and method for contacting a lubricant 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."

The present invention will be explained in detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples.

[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.

<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.

<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.

<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.

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

<Film formation process>
After the pretreatment step, each aluminum material was immersed in each coating treatment solution at the temperature and for the time specified in the "Coating Forming Treatment Solution" column in Table 1, and a coating containing zinc hydroxide (clay film of layered double hydroxide) was formed on the surface of the aluminum material by an ion exchange reaction with the alkaline component that had been attached in the pretreatment step.

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

[Comparative Example 1]
In Comparative Example 1, an aluminum material was subjected to a coating of a metal surface pretreatment agent on its surface by an aluminum zinc fluoride treatment method, and then subjected to a lubricating treatment 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 with a lubricant adhered thereto.

3. Evaluation of the 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 materials. The results are shown in Table 2.

<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 ring made of aluminum material coated with lubricant was pressed under a load of 200 tons at a compression rate 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. In the ring compression test, the relationship between the shape of the compressed ring and the friction coefficient is known. When the friction coefficient is small, both the inner and outer diameters are compressed so that they protrude outward. When the friction coefficient is large, the inner diameter protrudes inward, and the outer diameter protrudes less outward. Therefore, the dimensional change of the inner diameter can be measured to calculate the friction coefficient. The lower the friction coefficient, the higher the lubrication performance.

<Upset test>
The cylindrical test pieces 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 piece made of aluminum material with a lubricant attached 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 piece 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 piece 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 piece before and after compression.

<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 seizure ×: Seizure

Claims (8)

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. The metal surface pretreatment agent according to claim 1, wherein the coating does not contain fluorine atoms. The metal surface pretreatment agent according to claim 1 or 2, wherein the concentration of the alkaline component is 0.01 to 10 mol/L. 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. 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. 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. 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. 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.