Surface lubrication treatment method of metal substrate for cold working and surface lubrication treatment agent

Abstract

To provide a surface lubrication treatment method and a surface lubrication treatment agent of a metal substrate for cold working capable of performing surface treatment with a simple method while suppressing an environmental load.SOLUTION: A metal substrate is immersed in a treatment agent in which at least plant polyphenols, inorganic acids, and inorganic alkalis are mixed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for surface lubrication of a metal substrate for cold working and a surface lubrication agent. [Background technology]

[0002] Patent Document 1 discloses a surface lubricant and a surface lubricant treatment method for cold-worked steel. The document also discloses a surface lubricant for cold-worked steel that is made of a tannic acid solution. The document also discloses a surface lubricant treatment method for cold-worked steel, in which the steel surface is treated with the tannic acid solution and a lubricating film made of a metal soap and / or lubricating oil is formed on the surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 55-110778 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional methods have required multiple steps for surface lubrication treatment, making the process complicated. Furthermore, conventional methods have had the problem of placing a heavy metal burden on the environment.

[0005] An object of the present invention is to provide a surface lubricant treatment method and a surface lubricant treatment agent for a metal substrate for cold working, which can perform surface treatment in a simple manner while reducing the environmental load. [Means for solving the problem]

[0006] A surface lubrication treatment method according to one embodiment of the present disclosure involves immersing a metal substrate in a treatment liquid containing a mixture of at least plant polyphenols, inorganic acids, and inorganic alkalis.

[0007] Moreover, the surface lubricant treatment agent according to one embodiment of the present disclosure contains at least a plant polyphenol, an inorganic acid, and an inorganic alkali. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a surface lubricant treatment method and a surface lubricant treatment agent for a metal substrate for cold working, which can perform surface treatment by a simple method. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments thereof. Examples of the metal substrate for cold working that can be used in the present invention include zinc, nickel, magnesium, iron, aluminum, copper, and alloys thereof.

[0010] The treatment liquid used in the method for surface lubrication of a metal substrate for cold working according to this embodiment is described below. The treatment liquid contains a plant polyphenol, an inorganic acid, an inorganic alkali, and a solvent. Examples of the plant polyphenol include catechin, gallic acid, tannin, etc., extracted from plants such as tea leaves, grapes, maple, and persimmon, as well as compounds thereof.

[0011] The concentration of plant polyphenols in the treatment solution is determined based on the shape and material of the object to be chemically treated, taking into consideration the immersion state, ease of drainage, etc. For example, it can be 0.01 g / L or more and 40 g / L or less, and from the viewpoint of lubricity, it is preferably 0.1 g / L or more and 30 g / L or less, and more preferably 1 g / L or more and 20 g / L or less.

[0012] Examples of inorganic acids include nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, hydrosilicic acid, phosphoric acid, and the like, or compounds thereof, but the inorganic acids used in the present disclosure are not limited to these.

[0013] Examples of inorganic alkalis include sodium carbonate, calcium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium silicate, potassium silicate, calcium silicate, etc., or compounds thereof. However, the inorganic alkalis used in the present disclosure are not limited to these.

[0014] The treatment liquid preferably contains a carboxylic acid compound. The carboxylic acid compound in this embodiment is an organic acid having one or more carboxy groups. Both aliphatic and aromatic carboxylic acid compounds can be used as the carboxylic acid compound. The number of carboxy groups in the carboxylic acid compound is not particularly limited, but may be, for example, 1 to 5. From the viewpoint of lubricity, 1 to 3 is preferred, and 1 or 2 is even more preferred. The molecular size of the carboxylic acid compound is not particularly limited, but for example, a carboxylic acid compound having a molecular weight of 45 g / mol to 1000 g / mol may be used. From the viewpoint of lubricity, a molecular weight of 70 g / mol to 400 g / mol is preferred, and a molecular weight of 80 g / mol to 200 g / mol is even more preferred. Among aliphatic carboxylic acid compounds, a molecular weight of 70 g / mol to 120 g / mol is particularly preferred from the viewpoint of lubricity. Among aromatic carboxylic acid compounds, a molecular weight of 120 g / mol to 200 g / mol is particularly preferred from the viewpoint of lubricity. The number of carbon atoms in the carboxylic acid compound is not particularly limited, but may be, for example, 1 to 20, and from the viewpoint of lubricity, preferably 2 to 15, and more preferably 2 to 10.

[0015] Specific examples of carboxylic acid compounds that can be used in this embodiment include saturated aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid, and compounds thereof; unsaturated aliphatic monocarboxylic acids such as linolenic acid, linoleic acid, oleic acid, arachidonic acid, and sorbic acid, and compounds thereof; aliphatic dicarboxylic acids such as glutaric acid, malonic acid, oxalic acid, succinic acid, adipic acid, fumaric acid, and maleic acid, and compounds thereof; hydroxy acids such as lactic acid, malic acid, and citric acid, and compounds thereof; and aromatic carboxylic acids such as phthalic acid, isophthalic acid, benzoic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid, and compounds thereof, but are not limited to these.

[0016] The solvent of the treatment liquid in this embodiment is water, an alcohol such as methanol, ethanol, or propanol, acetone, or a combination thereof, with water being preferred from the viewpoint of cost and the environment.

[0017] In addition to the above components, the treatment solution may contain various additives. For example, it may contain antioxidants, preservatives, pH adjusters, surfactants, and reducing agents. The concentrations of the additives can be selected so as to obtain the desired effects of the additives, as long as the effects of the present invention are not impaired.

[0018] The treatment liquid can be prepared by dissolving each component in a solvent. The pH of the treatment liquid is not particularly limited, but is preferably set between 1.2 and 7.0 from the viewpoint of lubricity. The pH of the treatment liquid is more preferably set between 2.5 and 6.0, and particularly preferably between 3.8 and 5.0.

[0019] Next, the surface lubrication treatment method for a metal substrate for cold working according to this embodiment will be described. In the surface lubrication treatment method, a treatment liquid is first prepared by mixing plant polyphenols, inorganic acids, inorganic alkalis, and a solvent. At this time, the pH of the treatment liquid is preferably set between 1.2 and 7.0. Next, the metal substrate is immersed in the prepared treatment liquid. At this time, the temperature of the treatment liquid is preferably room temperature (10 to 20°C) to 70°C, and the treatment time is preferably 0.5 to 10 minutes. The treatment temperature and treatment time can be appropriately set depending on the type and shape of the metal substrate to be treated.

[0020] By applying the surface lubrication treatment method according to this embodiment to a metal substrate, a polyphenol coating is formed on the surface of the metal substrate. Then, a coating of an inorganic salt, which is a salt of an inorganic acid and an inorganic alkali, is formed to cover the polyphenol coating. Furthermore, a lubricating coating of a carboxylic acid compound is formed to cover the above two types of coatings. The formation of these three types of coatings is carried out in the same treatment solution.

[0021] In conventional surface lubrication treatment methods that combine zinc phosphate treatment and lubricant treatment, the surface of a metal substrate is generally treated through multiple treatment steps using multiple solutions. The present inventors have conducted research to solve the problem that conventional surface lubrication treatment methods involve multiple treatment steps, making the treatment complicated.

[0022] As a result, the inventors have found that by immersing a metal substrate in a treatment solution containing a mixture of plant polyphenols, an inorganic acid, and an inorganic alkali, it is possible to perform a surface lubrication treatment that provides a lubrication effect equivalent to or better than that of conventional methods. According to this method, the surface lubrication treatment can be completed in a single step. Thus, the surface lubrication treatment method according to the present disclosure can provide a surface lubrication treatment method for a metal substrate for cold working, which can perform surface treatment in a simple manner.

[0023] Furthermore, conventional surface lubrication treatment methods that combine zinc phosphate treatment and lubricant treatment have the problem of containing various heavy metals and oxidizing agents, which places a high burden on the environment. According to the surface lubrication treatment method of the present disclosure, even when using a treatment solution that does not contain heavy metals or oxidizing agents that place a high burden on the environment, it is possible to perform surface lubrication treatment that has the same or better lubrication effect as conventional methods.

[0024] Furthermore, in conventional methods, the metal substrate had to be washed with water between multiple processes. In the surface lubrication treatment method according to the present disclosure, the surface lubrication treatment is completed using a single treatment liquid, eliminating the need for a water washing step. This makes it possible to provide a surface lubrication treatment method for a metal substrate for cold working, which allows for a simple surface treatment. Furthermore, according to the surface lubrication treatment method of the present disclosure, no wastewater is generated in the water washing step, so it is possible to provide a surface lubrication treatment method with low environmental impact. [Example]

[0025] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0026] Carbon steel (compliant with JIS G4051) was used as a metal substrate test piece. The metal substrate was degreased and washed with water, then immersed at 60°C for 300 seconds in Treatment Solution 1, which contained 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 40 g / L of inorganic acid, 43.2 g / L of inorganic alkali, and 10 g / L of a carboxylic acid compound, and had a pH adjusted to 3.8 to 5.0. The substrate was then removed and dried to obtain a metal with a lubricating coating and a polyphenol coating (Example 1).

[0027] Next, treatment liquids 2 to 4 were prepared by adjusting the amounts of inorganic acid and inorganic alkali and carboxylic acid compound added to the treatment liquid, and surface lubrication treatment was carried out to obtain Examples 2 to 4. Treatment solution 2 contains 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 40 g / L of inorganic acid, 43.2 g / L of inorganic alkali, and 20 g / L of carboxylic acid compound. The treatment liquid 3 contains 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 66 g / L of inorganic acid, 71.3 g / L of inorganic alkali, and 10 g / L of a carboxylic acid compound. The treatment liquid 4 contains 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 66 g / L of inorganic acid, 71.3 g / L of inorganic alkali, and 20 g / L of a carboxylic acid compound. In the surface lubrication treatment in Examples 2 to 4, the conditions were the same as in Example 1, except that the concentrations of the treatment liquid were varied.

[0028] Furthermore, as examples, treatment liquids 5 and 6 containing no carboxylic acid compound were prepared, and surface lubrication treatment was carried out in the same manner as in Examples 1 to 4, to obtain Examples 5 and 6. The treatment liquid 5 contains 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 40 g / L of inorganic acid, and 43.2 g / L of inorganic alkali. The treatment liquid 6 contains 20 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 66 g / L of inorganic acid, and 71.3 g / L of inorganic alkali. The pH and temperature of the treatment liquids 5 and 6 are the same as those of the treatment liquids 1 to 4 used in Examples 1 to 4.

[0029] Furthermore, metal substrates were prepared as Comparative Examples 1 and 2, on which surface lubrication treatment was performed by a conventional method. In Comparative Example 1, carbon steel (meeting JIS G4051 standards) was used as the metal substrate. The metal substrate was degreased and washed with water, then immersed for 120 seconds at room temperature (approximately 20°C) in an aqueous solution containing 2 g / L of tannic acid (a commercially available reagent, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and adjusted to a pH of 3.8 to 5.0, followed by rinsing with water for 30 seconds. The substrate was then immersed for 30 seconds at room temperature (approximately 20°C) in Treatment Solution 7 containing 10 g / L of aluminum hydroxide and adjusted to a pH of 11 to 13, followed by rinsing with water for 30 seconds. The substrate was then immersed in a metal soap solution at 70°C for 300 seconds, removed, and dried to obtain a metal with a lubricating coating, aluminum coating, and polyphenol coating (Comparative Example 1). In Comparative Example 2, carbon steel (meeting JIS G4051 standards) was used as the metal substrate. The metal substrate was degreased and rinsed with water, then immersed in a zinc phosphate treatment solution at 80°C for 300 seconds, rinsed with water for 30 seconds, immersed in a metal soap solution at 70°C for 300 seconds, removed, and dried to obtain a metal with a lubricating coating and a zinc phosphate coating (Comparative Example 2).

[0030] Thereafter, in order to measure the friction coefficients of Examples 1 to 6 and Comparative Examples 1 and 2, the metal substrates that had been subjected to the surface lubrication treatment were measured for the friction coefficient using a friction tester (Hundy Rub Tester TL701, manufactured by Trinity Lab Co., Ltd.). Furthermore, in order to measure the press load of the metal substrates of Examples 1 to 6 and Comparative Examples 1 and 2, each sample was pressed by a forging press and the load was measured. The results are shown in Table 1.

[0031] [Table 1]

[0032] As the above results show, the metal substrates (Examples 1 to 6) subjected to surface lubrication treatment with the treatment liquid according to the present disclosure have friction coefficients as low as those of Comparative Examples 1 and 2, which were subjected to conventional surface lubrication treatments that have a high environmental impact. Furthermore, it was confirmed that the press loads of the metal substrates of Examples 1 to 4 in particular were reduced to the same level as or lower than those of Comparative Examples 1 and 2.

[0033] Furthermore, as can be seen from a comparison between Examples 1 to 6 and Comparative Examples 1 and 2, in the surface lubrication treatment method according to this embodiment, the press load during forging can be further reduced by including a carboxylic acid compound in the treatment liquid.

[0034] The surface lubrication treatment method according to the present disclosure is not limited to the above-described embodiment. For example, after the above-described surface lubrication treatment method is performed, the metal substrate may be washed with water and immersed in a metal soap solution. This configuration can further enhance the load reduction effect.

Claims

1. A method for surface lubrication treatment of a metal substrate for cold working, comprising immersing the metal substrate in a treatment liquid containing a mixture of at least plant polyphenols, inorganic acids, and inorganic alkalis.

2. 2. The method for surface lubrication treatment of a metal substrate for cold working according to claim 1, wherein the treatment liquid contains a carboxylic acid compound.

3. 2. The surface lubrication treatment method according to claim 1, wherein the inorganic acids include at least one of nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, hydrosilicic acid, phosphoric acid, and compounds thereof.

4. 3. The surface lubrication treatment method according to claim 1, wherein the inorganic alkalis include at least one of sodium carbonate, calcium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium silicate, potassium silicate, calcium silicate, and compounds thereof.

5. The surface lubrication treatment method according to claim 1 or 2, wherein the plant polyphenols include at least one of catechin, gallic acid, tannin, and compounds thereof extracted from plants such as tea leaves, grapes, maple, and persimmon.

6. The carboxylic acid compound is selected from the group consisting of saturated aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid, unsaturated aliphatic monocarboxylic acids such as linoleic acid, linoleic acid, oleic acid, arachidonic acid, and sorbic acid, and compounds thereof, aliphatic dicarboxylic acids such as glutaric acid, malonic acid, oxalic acid, succinic acid, adipic acid, fumaric acid, and maleic acid, and compounds thereof, hydroxy acids such as lactic acid, malic acid, and citric acid, and compounds thereof, and aromatic carboxylic acids such as phthalic acid, isophthalic acid, benzoic acid, terephthalic acid, salicylic acid, gallic acid, mellitic acid, and cinnamic acid, and compounds thereof.

7. The metal substrate is immersed in the treatment solution at a temperature of 10°C to 70°C for 0.5 to 10 minutes. The surface lubrication treatment method according to claim 1 or 2, wherein the surface lubrication treatment method comprises:

8. 3. The surface lubrication treatment method according to claim 1, wherein the treatment liquid contains 0.01 g / L to 40 g / L of the plant polyphenols.

9. 3. The surface lubrication treatment method according to claim 1, wherein the pH of the treatment solution is 1.2 or more and 7.0 or less.

10. A surface lubricating treatment liquid for a metal substrate for cold working, comprising at least a plant polyphenol, an inorganic acid, an inorganic alkali, and a carboxylic acid compound.

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