JP7108299B2 - Chemical polishing liquid and method for producing metal material - Google Patents

Description

The present invention relates to a chemical polishing treatment liquid and a method for producing a metal material using the same.

Titanium and titanium alloys can form a strong oxide film on the surface by reacting with oxygen in the air. Due to the presence of this oxide film, titanium and titanium alloys can achieve high corrosion resistance even in corrosive environments. Furthermore, titanium and titanium alloys are lightweight and have high biocompatibility (for example, they are less likely to cause metal allergy). Due to such corrosion resistance, lightness, biocompatibility, etc., it is applied to various uses such as medical treatment.

By polishing the surfaces of titanium and titanium alloys, the surfaces are smoothed, thereby suppressing the growth of bacteria. On the other hand, fine unevenness may be formed on the surface instead of completely smoothing it. As a result, it is possible to improve the adhesion with the plated layer by further post-processing such as plating.

Patent Literature 1 discloses a method for chemically polishing titanium or titanium alloys. This document discloses a chemical polishing liquid containing a specific fluorine compound.

JP-A-1-272785

As described above, a strong oxide film is formed on the surface of titanium and titanium alloys. Therefore, titanium and titanium alloys are resistant to attack by acids and alkalis commonly used in polishing. This makes surface machining of titanium and titanium alloys difficult.

In the prior art, fluorine compounds have been used for the purpose of removing chemically strong oxide films, polishing the surface uniformly and smoothly, and forming uniform and fine irregularities on the surface. .

Examples of fluorine compounds include hydrofluoric acid, sodium fluoride, and sodium hydrogen fluoride. Patent Document 1 discloses the use of a combination of nitric acid and hydrogen peroxide.

However, fluorine compounds are highly corrosive and therefore highly toxic. If an accident involving the handling of fluorine compounds occurs, it not only poses a danger to the human body but also adversely affects the environment. Therefore, it is necessary to pay close attention to the handling of fluorine compounds.

There are also strict regulations on disposal of waste after using fluorine compounds. Therefore, waste disposal is costly.

In view of such safety to the human body, adverse effects on the environment, etc., the present invention provides a conventional chemical polishing treatment liquid (that is, a chemical polishing treatment liquid containing a fluorine compound) without substantially using a fluorine compound. An object of the present invention is to provide a chemical polishing treatment liquid which is comparable to the conventional one.

The present inventors found out the following phenomenon as a result of earnest research. First, in chemical agents for polishing titanium, safety and environmental problems can be addressed by not using fluorine compounds that are used for removing the oxide film on the surface of titanium and chemically polishing it.

However, this alone is not sufficient, and the reason for this is that it is difficult to remove and chemically polish the oxide film of titanium with acid compounds other than fluorine compounds. Therefore, the present inventors used a combination of specific components as a substitute for fluorine compounds. More specifically, (1) at least one alkali metal hydroxide, (2) hydrogen peroxide, and (3) at least one ion selected from chloride ions, sulfate ions and nitrate ions. used in combination. The inventors have found that this makes it possible to remove the oxide film on the surface of titanium and polish it at the same time. They also found that the titanium surface after processing is comparable to the titanium surface processed by conventional techniques.

The present invention completed based on the above findings includes the following inventions in one aspect.
(Invention 1)
A chemical polishing treatment liquid,
(1) at least one alkali metal hydroxide;
(2) hydrogen peroxide;
(3) at least one ion selected from chloride ions, sulfate ions and nitrate ions;
(4) at least one selected from organic acids and salts thereof, and (5) at least one nonionic surfactant,
A chemical polishing treatment liquid that does not substantially contain a fluorine compound.
(Invention 2)
The chemical polishing treatment liquid of Invention 1 used for chemical polishing treatment of metal materials,
A chemical polishing liquid, wherein the metal material is at least one selected from titanium and titanium alloys.
(Invention 3)
The chemical polishing liquid according to Invention 1 or 2, wherein the organic acid is a carboxylic acid.
(Invention 4)
A method for manufacturing a metal material,
A method comprising the step of immersing the metal material in the chemical polishing treatment liquid according to any one of Inventions 1 to 3.

In one aspect of the present invention, the chemical polishing liquid contains substantially no fluorine compounds. As a result, safety to the human body can be ensured, and adverse effects on the environment can be reduced. Further, in one aspect of the present invention, the chemical polishing treatment liquid can achieve uniformity in both gloss treatment and surface roughening treatment.

It represents the state of the surface of the material after the chemical polishing treatment.

Specific embodiments for carrying out the present invention will be described below. The following description is intended to facilitate understanding of the invention. it is not intended to limit the scope of the invention.

0. Definition (1) Gloss treatment A process to remove the titanium oxide film and create a smooth surface condition on the metal surface to obtain a glossy design.
uniform surface condition visually and by microscope;
A glossiness of 80 or more and a surface roughness Ra of 0.45 or less are defined as satisfying all of these.
(2) Roughening treatment A process to remove the titanium oxide film and create fine unevenness on the surface of the metal to obtain a rough and low-gloss design like the surface of a pear skin.
It is defined as satisfying all of the following: a uniform surface condition visually and by a microscope; a glossiness of 20 or less; and a surface roughness Ra of 1.5 or more.

1. Chemical Polishing Liquid In one embodiment, the present invention includes a chemical polishing liquid. The chemical polishing treatment liquid can include at least the following components:
(1) at least one alkali metal hydroxide;
(2) hydrogen peroxide;
(3) at least one ion selected from chloride ions, sulfate ions and nitrate ions;
(4) at least one selected from organic acids and salts thereof, and (5) at least one nonionic surfactant

1-1. Alkali Metal Hydroxide Alkali metal hydroxide is a component that contributes to the appearance after processing. Although the type of alkali metal hydroxide is not particularly limited, examples thereof include sodium hydroxide, potassium hydroxide, and the like. Although the concentration of the alkali metal hydroxide is not particularly limited, it is preferably in the range of 10-300 g/L, more preferably 50-100 g/L. Within the above range, it becomes easier to control the processed state of the surface of the metal material. For example, lower concentrations give a glossy appearance. On the other hand, higher concentrations can give a rough surface appearance (like the surface of a pear skin).

1-2. Hydrogen Peroxide Like alkali metal hydroxide, hydrogen peroxide is also a component that contributes to the appearance after processing. The concentration of hydrogen peroxide is not particularly limited, but is preferably in the range of 50 to 500 g/L, more preferably 100 to 300 g/L in terms of the concentration when 35% hydrogen peroxide solution is added ( For example, in the case of 50 g/L, 50 g of 35% hydrogen peroxide solution is contained in 1 L including 35% hydrogen peroxide solution). Within the above range, it becomes easier to control the processed state of the surface of the metal material. For example, lower concentrations give a glossy appearance. On the other hand, higher concentrations can give a rough surface appearance (like the surface of a pear skin).

1-3. At least one ion selected from chloride ions, sulfate ions and nitrate ions These ions contribute to obtaining a uniform and stable surface. Chloride ions, sulfate ions and nitrate ions may also be provided in one or more salt forms selected from sodium salts, potassium salts, ammonium salts, calcium salts and magnesium salts. The total concentration of these ions is not particularly limited, but is preferably in the range of 10-400 g/L, more preferably 20-200 g/L. Within this range, a uniform and stable surface can be obtained.

1-4. Organic acids and their salts Although the types of organic acids and their salts are not particularly limited, carboxylic acids are preferred, and alkylcarboxylic acids are more preferred. The number of carboxylic groups in the compound is not particularly limited, and may be 1-3. The alkyl group of the alkylcarboxylic acid may be linear or branched.

Furthermore, the carboxylic acid may be esterified. Specific examples of carboxylic acids include: oxalic acid, lactic acid, citric acid, gluconic acid, succinic acid, acetic acid, malonic acid. Further, specific examples of esterified carboxylic acids include the following: methyl-esterification, ethyl-esterification, and butyl-esterification. These esterifications are not limited to monoesterification, but include diesterification, triesterification, and the like.

Organic acid salts may be provided in one or more salt forms selected from sodium salts, potassium salts, and ammonium salts.

Examples of particularly preferred organic acids include lactic acid, lactates and esters thereof, and oxalic acid, oxalates and oxalates. These preferred organic acids can achieve a uniform appearance.

The total concentration of organic acids and their salts is not particularly limited, but is preferably in the range of 1 to 200 g/L, more preferably 5 to 100 g/L. If the concentration of the organic acid and these salts is too low, the appearance may become uneven due to insufficient polishing or the like after long-term use (especially when impurities increase). If the concentration of the organic acid and its salt is too high, precipitation and the like may occur, and it may be economically disadvantageous.

1-5. Nonionic Surfactants Nonionic surfactants can contribute to material protection and a uniform and stable polished surface. Surfactants include surfactants such as anionic, cationic, amphoteric and nonionic. However, nonionic surfactants are preferred for the purpose of realizing these benefits. Preferred nonionic surfactants include aliphatic polyethers, alkyl polyethylene oxide alcohols, polyoxyethylene alkyl ethers, nonylphenyl ethoxylates and the like. Although the total concentration of the nonionic surfactant is not particularly limited, it is preferably in the range of 0.01 to 10 g/L, more preferably 0.1 to 5 g/L.

1-6. Other Ingredients In one embodiment, the present invention includes a chemical polishing solution comprising the ingredients described above. In another embodiment, the present invention includes a chemical polishing treatment liquid that further contains other ingredients in addition to the ingredients mentioned above. Other components include, for example, phenol derivatives as stabilizers for hydrogen peroxide.

1-7. Other Excluded Components In one embodiment, the chemical polishing solution of the present invention excludes specific components. In a further embodiment, the chemical polishing treatment liquid of the present invention does not substantially contain a fluorine compound (the "fluorine compound" described herein includes elemental fluorine). "Substantially free" means that the content is such that it does not contribute to the polishing of the metal material. For example, the total concentration of fluorine compounds may be 0.01 g/L or less, preferably 0.0001 g/L or less, more preferably 0.00001 g/L or less, Most preferably 0 g/L. This improves safety to the human body. Moreover, adverse effects on the environment can be reduced. Furthermore, costs associated with waste disposal can be reduced.

1-8. Solvent In one embodiment, the chemical polishing treatment liquid of the present invention is an aqueous solution. That is, there is no need to use an organic solvent.

2. Method for Producing Metal Material In one embodiment, the present invention includes a method for producing a metal material using the chemical polishing treatment liquid described above. The metal material is polished.

2-1. Types of Polishing Polishing includes chemical polishing, physical polishing, electropolishing, chemical-mechanical polishing, and the like. In one embodiment, the method of the present invention involves chemical polishing. More specifically, the metal material may be immersed in the chemical polishing treatment liquid described above.

2-2. Metals to be Treated In one embodiment of the present invention, examples of metals to be treated include titanium and titanium alloys. Titanium alloys have titanium as the main component (i.e. the largest amount of each component) and other minor components selected from, for example, the following elements: aluminum, nickel, molybdenum, vanadium, niobium, iron. , chromium, and combinations of one or more of these.

2-2. Pretreatment Steps Prior to chemical polishing as described above, the metal material may be subjected to several treatments. Examples of pretreatment include treatment with a solution containing surfactants, inorganic acid ions, hydroxides, metal ions, and the like. This cleans and activates the surface of the metal material.

2-3. Chemical Polishing Process As described above, in the chemical polishing process, the metal material can be immersed in the above chemical polishing treatment liquid. Although the temperature during the treatment is not particularly limited, it is preferably 20 to 60°C. The treatment time is also not particularly limited, but is preferably 6 minutes to 60 minutes, more preferably 10 minutes or longer. Within the above range, it becomes easier to control the processed state of the surface of the metal material. On the other hand, if the temperature is outside the above range, for example, if the temperature is too high, bumping of the processing liquid and/or excessive polishing of the surface of the material may occur. If the temperature is too low, the reaction will not proceed and there will be insufficient polishing, which can result in an uneven appearance. If the treatment time is too short, there is a possibility of insufficient polishing. Even if the treatment time exceeds 60 minutes, the surface of the material may be excessively polished, resulting in a decrease in productivity.

The chemical polishing process described above is divided into at least two treatments (brightening and roughening). By appropriately setting parameters within the above-described conditional range, it is possible to selectively perform gloss processing and surface roughening processing.

2-3-1. Lowering the temperature during the glossing treatment increases the tendency to achieve a glossy appearance. However, the numerical range of temperature is not particularly limited. The reason for this is, for example, that it is possible to achieve a glossy appearance even at high temperatures by setting other parameters. For the same reason, the numerical ranges of other parameters are not particularly limited.

As conditions other than temperature, shorter treatment times are more likely to achieve a glossy appearance.

2-3-2. Roughening Treatment On the other hand, if the temperature during treatment is increased, the tendency to achieve a roughened appearance increases. Also, the longer the treatment time, the more likely it is that a roughened appearance can be achieved.

As conditions other than temperature and treatment, if the concentration of at least one of the following components is increased, the tendency to achieve a roughened appearance increases.
at least one alkali metal hydroxide, and hydrogen peroxide

2-4. Post- Treatment Process After the chemical polishing process, a further surface treatment may be carried out. Examples of surface treatments include plating, chemical conversion film forming, overcoating, and painting for the purpose of corrosion resistance and appearance. When performing these treatments, it is desirable to perform the roughening treatment described above.

2-5. Properties of Metallic Materials After Chemical Polishing Metallic materials after chemical polishing, preferably immediately after chemical polishing, have several excellent properties. Specifically, in both the gloss treatment and the roughening treatment, a highly uniform appearance can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention. These examples, like the embodiments of the invention described above, are intended to facilitate understanding of the invention. it is not intended to limit the scope of the invention.

3. Preparation of metal material and evaluation method A test piece of titanium was prepared as a metal material. Appropriate pretreatment such as degreasing was applied to the test piece. After that, a chemical polishing treatment was performed.

Three test pieces were evaluated for each example. The evaluation contents include visual confirmation of appearance, measurement of glossiness with a gloss meter (PG-IIM manufactured by Nippon Denshoku Industries Co., Ltd.), and surface roughness with a surface roughness meter (SJ-400 manufactured by Mitutoyo Co., Ltd.). and the measurement of the thickness Ra.

(1) Evaluation of Gloss by Visual Visual inspection “Glossy” if glossy; and

(2) Evaluation of uniformity by visual observation Observation was made by visual observation. "If the surface is uniform, it is evaluated as ◯", and "If the surface is uneven, it is evaluated as ×". More specifically, a Keyence microscope VHX-5000 was used to photograph the surface of the material. Using the conversion function of the device, the photographed image was converted into a 3D image (see FIG. 1).

(3) Evaluation of Glossiness If the number at 60° of a commonly used glossmeter is large, it indicates that the material is glossy, and if the number indicated by the glossmeter is small, it indicates that the material is not glossy.

(4) Evaluation of Surface Roughness The evaluation of surface roughness is the value of arithmetic mean roughness Ra. A small value of Ra indicates a glossy state, and a large value of Ra indicates a rough surface state.

Based on the above evaluation, the surface state after chemical polishing in Examples described later is defined.
(i) a uniform surface condition in terms of visual gloss and microscopic appearance;
Glossiness is 80 or more Surface roughness Ra is measured at 5 points on the test piece, and the average value is 0.45 or less Surface roughness Ra is measured at 5 points on the test piece, and its standard deviation is 0.05 or less.

(ii) Rough surface Visually and with a microscope, the appearance is uniform. The glossiness is 20 or less. The surface roughness Ra is 1.5 or more. The surface roughness Ra is 5 points on the test piece. Measure and calculate the standard deviation. The standard deviation was divided by the average value of the surface roughness Ra, and when the value calculated as a percentage was less than 15, all of these were judged to be a highly uniform and rough surface state.

(iii) Non-uniform semi-gloss visual and microscopic appearance, or the presence of stains and unevenness The glossiness is 21 to 79 The surface roughness Ra is more than 0.45 and less than 1.5 Surface roughness The thickness Ra is measured at 5 points on the test piece, and its standard deviation is calculated. The standard deviation is divided by the average value of the surface roughness Ra, and the value calculated as a percentage is 15 or more.

(Example 1)
A commercially available pure titanium plate (surface area: 1 dm ² ) that had undergone an appropriate pretreatment was treated with 100 g/L of sodium hydroxide, 200 g/L of 35% hydrogen peroxide solution, and sodium sulfate so that the sulfate ions would be 50 g/L. , 50 g / L of sodium oxalate as an organic acid salt, and 0.2 g / L of a nonylphenol ethoxylate-containing nonionic surfactant are added, immersed in a treatment solution adjusted to a temperature of 30 ° C. for 20 minutes, and the appearance is evaluated.

(Example 2)
A test was conducted under the same conditions as in Example 1 except that potassium hydroxide was used in place of sodium hydroxide in Example 1.

(Examples 3 to 10)
A test was conducted under the same conditions as in Example 1 using the compounds shown in Table 1 instead of sodium sulfate in Example 1.

(Examples 11 to 19)
The test was carried out under the same conditions as in Example 1 using the organic acid salts shown in Table 2 instead of sodium oxalate in Example 1.

(Examples 20-24)
Instead of sodium oxalate in Example 1, the organic acid compound shown in Table 3 was used and added at 5 g/L, and the test was conducted under the same conditions as in Example 1.

(Examples 25-27)
The nonionic surfactant shown in Table 4 was used instead of the nonionic surfactant in Example 1, and 5 g/L was added, and the test was conducted under the same conditions as in Example 1.

(Examples 28-39)
For Examples 28 to 39, the test was conducted by changing the concentration conditions in the chemical polishing liquid of Example 1 as shown in Table 5.

(Examples 40-43)
Examples 40 to 43 were carried out in Example 1 at treatment temperatures of 20° C. (Example 40), 40° C. (Example 41), 50° C. (Example 42) and 60° C. (Example 43).

(Examples 44-48)
For Examples 44 to 48, in Example 1, the treatment time was 10 minutes (Example 44), 30 minutes (Example 45), 40 minutes (Example 46), 50 minutes (Example 47), 60 minutes ( Example 48) was carried out.

(Examples 49-60)
In Examples 49 to 60, the concentration conditions in the chemical polishing liquid of Example 1 were varied as shown in Table 5 (Examples 28 to 39), and the test was conducted at a processing temperature of 50°C.

(Examples 61-72)
In Examples 61 to 72, the concentration conditions in the chemical polishing liquid of Example 1 were changed as shown in Table 5 (Examples 28 to 39), and the test was carried out with a treatment time of 60 minutes.

(Comparative example 1)
A commercially available pure titanium plate (surface area: 1 dm ² ) that has undergone an appropriate pretreatment is coated with a commercially available polishing agent for titanium and titanium alloys (Titanic 99: product name, manufactured by Nippon Surface Chemical Co., Ltd., containing a fluorine compound (approximately 20 g as a fluorine compound). /L), Titanic 99A: 650 mL/L, Titanic 99B: 350 mL/L) were immersed in a treatment solution adjusted to a temperature of 70° C. for 10 minutes to polish the titanium surface and evaluate its appearance.

(Comparative example 2)
A commercially available pure titanium plate (surface area: 1 dm ² ) that had undergone appropriate pretreatment was adjusted to a temperature of 70°C with 50% hydrofluoric acid (50% mL/L) and 67.5% nitric acid 150% (mL/L). The titanium surface was polished by immersing it in the polishing treatment liquid for 10 minutes, and its appearance was evaluated.

(Comparative Examples 3-5)
In Comparative Examples 3-5, a commercially available pure titanium plate (surface area: 1 dm ² ) that had undergone an appropriate pretreatment was immersed for 30 minutes in a polishing solution containing 300 mL/L of acid shown in Table 6 and adjusted to a temperature of 70°C. The surface was polished and evaluated for its appearance.

(Comparative Example 6)
As Comparative Example 6, a test was conducted under the same conditions as in Example 1, except that a processing solution obtained by removing sodium hydroxide from the processing solution of Example 1 was used.

(Comparative Example 7)
As Comparative Example 7, a test was conducted under the same conditions as in Example 1, except that the treatment solution obtained by removing the hydrogen peroxide solution from the treatment solution of Example 1 was used.

(Comparative Example 8)
As Comparative Example 8, a test was conducted under the same conditions as in Example 1, except that a processing solution obtained by removing sodium sulfate from the processing solution of Example 1 was used.

(Comparative Example 9)
As Comparative Example 9, a test was conducted under the same conditions as in Example 1, except that a processing solution obtained by removing sodium oxalate from the processing solution of Example 1 was used.

(Comparative Example 10)
As Comparative Example 10, a test was conducted under the same conditions as in Example 1, except that the treatment liquid obtained by removing the nonionic surfactant from the treatment liquid of Example 1 was used.

(Comparative Examples 11-12)
Comparative Examples 11 and 12 were carried out in Example 1 at temperatures of 10° C. (Comparative Example 11) and 80° C. (Comparative Example 12).

(Comparative Examples 13-14)
Comparative Examples 13 and 14 were carried out in Example 1 with a treatment time of 5 minutes (Comparative Example 13) and 80 minutes (Comparative Example 14).

Appearance, uniformity, glossiness, and Ra were evaluated for Examples 1 to 72 and Comparative Examples 1 to 14. Table 7 shows the evaluation results.

In any example (gloss finish), the standard deviation of Ra was sufficiently low. In addition, the standard deviation of Ra and the percentage of the average value were sufficiently low in all examples (rough surface finish). Therefore, the desired uniformity could be achieved in all examples.

On the other hand, in Comparative Examples 1 and 2, although the desired uniformity was achieved, the treatment liquid contained a fluorine compound.

Comparative Examples 3 to 11 and 13 were semi-glossy and had a large standard deviation of Ra. Also, the standard deviation of Ra and the percentage of the average value were increased.

Specific embodiments of the present invention have been described above. The above embodiments are only specific examples of the present invention, and the present invention is not limited to the above embodiments. For example, technical features disclosed in one of the above embodiments can be provided in other embodiments. Also, unless otherwise stated, for a particular method, some steps may be interchanged with other steps, and additional steps may be added between two particular steps. The scope of the invention is defined by the claims.

Claims (4)

A chemical polishing treatment liquid,
(1) 10 g/L or more of at least one alkali metal hydroxide;
(2) hydrogen peroxide of 50 g/L or more in terms of concentration when 35% hydrogen peroxide solution is added;
(3) 10 g/L or more of at least one ion selected from chloride ions, sulfate ions and nitrate ions;
(4) at least one selected from 1 g/L or more of alkylcarboxylic acids, their esters and their salts, and (5) 0.01 g/L or more of at least one nonionic surfactant contains,
A chemical polishing liquid having a total fluorine compound concentration of 0.01 g/L or less. The chemical polishing liquid according to claim 1, which is used for chemical polishing of metal materials,
A chemical polishing liquid, wherein the metal material is at least one selected from titanium and titanium alloys. 3. The chemical polishing liquid according to claim 1, wherein (4) is an alkylcarboxylic acid. A method for manufacturing a metal material,
The method, comprising the step of immersing the metal material in the chemical polishing treatment liquid according to any one of claims 1 to 3.

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