JP7144008B2 - Method for manufacturing stainless steel processed products in which fingerprints are inconspicuous - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a stainless processed product having surface unevenness, on which attached fingerprints and stains are inconspicuous. Furthermore, the present invention relates to a method for producing a color-developed stainless-steel processed product on which attached fingerprints and stains are inconspicuous.

Stainless processed products are widely used as stainless steel processed products such as industrial products and household goods because of their excellent corrosion resistance. However, fingerprints adhere to the surfaces of stainless processed products used in areas that are likely to come into contact with human hands during use. When a fingerprint adheres to the surface of a stainless processed product, depending on the viewing angle, the fingerprint adhered portion appears pale or tinged with reddish brown in relation to its surroundings, making the surface look dirty. This fingerprint smudge poses a problem in the appearance of stainless processed products.

As a method of imparting resistance to fingerprint stains (hereinafter referred to as "fingerprint resistance"), a technique of forming a water- and oil-repellent film on the surface of a metal material has been proposed. Patent Literature 1 discloses forming a coating layer containing a fluorine compound. However, the formation of a coating layer impairs the unique texture of the metal material, and in the case of stainless processed products with excellent corrosion resistance, it impairs the properties inherent in stainless steel. Further, in the case of processed stainless steel products that have undergone coloring treatment, there is a problem that the coating layer causes a change in color tone.

As a method for imparting anti-fingerprint properties, Patent Document 2 discloses that a metal surface on which fingerprints are adhered is inconspicuous by minimizing the light scattering phenomenon caused by the extremely fine unevenness of the metal surface. It is proposed to form Specifically, it is disclosed that the center line average roughness (Ra) is 0.5 μm or more, and that unevenness in a wavelength range of 10 μm or less is not detected by power spectrum analysis of surface roughness. However, it is difficult to control the production of processed products by controlling such ultrafine irregularities on the metal surface, and from the viewpoint of productivity, it is not suitable as a method for imparting anti-fingerprint properties.

Patent Literature 3 discloses a method for producing stainless steel having excellent in-plane uniformity of uneven surface shape with excellent fingerprint hiding properties, corrosion resistance, washability, etc., by subjecting stainless steel to blasting and electropolishing. ing. However, even if such a method is adopted, the fingerprint resistance is not necessarily satisfactory.

JP 2015-221528 A JP-A-11-226606 Japanese Patent No. 5860991

The present invention provides a stainless steel product excellent in fingerprint resistance and free from surface color unevenness, a stainless steel product subjected to coloring treatment, and a method for producing the same.

The problems of the present invention can be solved by the following aspects. In particular,

(Aspect 1) A sandblasting step of forming an uneven surface on the surface of the stainless steel workpiece by blowing a mixture of an abrasive and compressed air onto the surface of the stainless steel workpiece ; An electrolytic cleaning treatment step in which anodic electrolytic cleaning is performed using a stainless processed product as an anode , and an electrolytic polishing treatment step in which the electrolytically cleaned stainless steel processed product surface is electrolytically polished. A method for manufacturing a stainless processed product.
By performing electrolytic cleaning after sandblasting, the fine abrasives remaining on the surface of the stainless steel processed by sandblasting and the ground stainless steel shavings are removed. This is because the light scattering on the stainless-steel processed surface effectively acts to conceal the adhered finger.

(Aspect 2) A sandblasting step of forming an uneven surface on the surface of the stainless steel workpiece by blowing a mixture of an abrasive and compressed air onto the surface of the stainless steel workpiece ; An electrolytic cleaning process in which anodic electrolytic cleaning is performed using a stainless steel product as an anode , an electrolytic polishing process in which the surface of the electrolytically cleaned stainless steel product is electrolytically polished, and an electrolytically polished stainless steel product is subjected to chromic acid and sulfuric acid. A coloring treatment process in which a colored film is formed on the surface of a stainless steel product by immersing it in a coloring treatment liquid consisting of a mixed solution, and the stainless steel product that has undergone coloring treatment is immersed in a hardening treatment liquid consisting of a mixed solution of chromic acid and phosphoric acid. and a curing treatment step of curing the coloring film formed in the coloring treatment step.
By performing electrolytic cleaning after sandblasting, the fine abrasives remaining on the surface of the stainless steel processed by sandblasting and the ground stainless steel shavings are removed. This is because the light scattering on the colored stainless steel processed surface effectively acts to hide the adhered finger.

According to the present invention, by performing electrolytic cleaning after sandblasting, the surface unevenness of the stainless steel processed product becomes uniform, light scattering due to the surface unevenness is effective for hiding fingerprints, and the product has excellent fingerprint resistance and no color unevenness. , stainless steel processed products can be realized.

FIG. 2 is a process chart showing the flow of steps constituting the method for manufacturing a stainless processed product of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing which shows the flow of the process which comprises the manufacturing method of the colored stainless steel processed goods of this invention. 1 is a photograph showing the appearance of a colored stainless processed product produced by the production method of the present invention.

FIG. 1 is a process diagram showing the flow of steps constituting the method for producing a stainless processed product having surface irregularities with excellent anti-fingerprint properties according to the present invention. The stainless processed article of the present invention having surface irregularities with excellent anti-fingerprint properties can be produced by performing sandblasting, electrolytic cleaning, and electrolytic polishing in this order. In particular, the anti-fingerprint property is improved by performing the electrolytic cleaning treatment after the sandblasting treatment.
FIG. 2 is a process chart showing the flow of steps constituting the method for producing a colored stainless processed product having surface irregularities with excellent anti-fingerprint properties according to the present invention. The colored stainless steel product having surface irregularities with excellent anti-fingerprint properties of the present invention can be produced by performing sandblasting, electrolytic cleaning, electrolytic polishing, coloring, and curing in this order. It is the same as the stainless processed product shown in FIG. 1 in that the anti-fingerprint property is improved by performing the electrolytic cleaning treatment after the sandblasting treatment.
Hereinafter, in the present invention, the metal material and the processed metal material to be treated, and the sandblasting process, the electrolytic cleaning process, the electrolytic polishing process, the coloring process, and the hardening process, which are the processing methods, will be described in this order. The evaluation method will also be explained. In addition, this invention is not limited to the aspect for implementing the following invention.

(1) Metal material As the metal material used in the present invention, if the metal material can be subjected to surface unevenness processing by sandblasting, electrolytic cleaning, and electrolytic polishing, and can be chemically colored, austenitic It is not limited to stainless steel materials such as stainless steel and ferritic stainless steel. Specifically, aluminum, aluminum alloys, iron, iron alloys, stainless steel, nickel, nickel alloys, titanium, titanium alloys, magnesium, magnesium alloys, tungsten, tungsten alloys, molybdenum, molybdenum alloys, zinc, zinc alloys, etc. and known metal materials can also be used.

As the aluminum and aluminum alloy, for example, those containing 40% by mass or more, 80% by mass or more, or 99% by mass or more of Al can be used. For example, aluminum and aluminum alloys compliant with JIS H 4000 to JIS H 4180, JIS H 5202, JIS H 5303, or JIS Z 3232 to JIS Z 3263 can be used. For example, aluminum with 99.00% by mass or more of Al, represented by alloy numbers 1085, 1080, 1070, 1050, 1100, 1200, 1N00, and 1N30 standardized in JIS H 4000, or an alloy thereof is used. be able to.

Examples of iron alloys that can be used include stainless steel, mild steel, carbon steel, iron-nickel alloys, and steel. For example, iron or iron alloys described in JIS G 3101 to JIS G 7603, JIS C 2502 to JIS C 8380, JIS A 5504 to JIS A 6514 or JIS E 1101 to JIS E 5402-1 can be used.
As stainless steel, SUS 301, SUS 304, SUS 310, SUS 316, SUS 430, SUS 631 (all of which are JIS standards) or the like can be used. Mild steel having a carbon content of 0.15% by mass or less can be used, and mild steel described in JIS G3141 can be used. The iron-nickel alloy contains 35 to 85% by mass of Ni, with the balance being Fe and unavoidable impurities. Specifically, an iron-nickel alloy described in JIS C2531 or the like can be used.

As nickel and nickel alloys, nickel containing 40% by mass or more, 80% by mass or more, or 99.0% by mass or more can be used. For example, nickel or a nickel alloy standardized in JIS H 4541 to JIS H 4554, JIS H 5701, JIS G 7604 to JIS G 7605, and JIS C 2531 can be used. Further, for example, nickel having a Ni content of 99.0% by mass or more, represented by alloy numbers NW2200 and NW2201 described in JIS H4551, or an alloy thereof can be used.

Titanium and titanium alloys that contain Ti in an amount of 40% by mass or more, 80% by mass or more, or 99.0% by mass or more can be used. For example, titanium and titanium alloys compliant with JIS H 4600 to JIS H 4675 and JIS H 5801 can be used.

Magnesium and magnesium alloys that contain, for example, 40% by mass or more, 80% by mass or more, or 99.0% by mass or more of Mg can be used. For example, magnesium and magnesium alloys specified in JIS H 4201 to JIS H 4204, JIS H 5203 to JIS H 5303, and JIS H 6125 can be used.

As the tungsten and tungsten alloy, for example, those containing 40% by mass or more of W, 80% by mass or more, or 99.0% by mass or more of W can be used. For example, tungsten and tungsten alloys specified in JIS H 4463 can be used.

As molybdenum and molybdenum alloys, those containing 40% by mass or more, 80% by mass or more, or 99.0% by mass or more of Mo can be used.

(2) Metal material processed product The metal material processed product of the present invention includes a metal material processed product having a solid surface on which no surface coating layer such as coating is formed, specifically construction materials (handrails, fences). , food manufacturing equipment (cutting machines, washing machines, mixers, heat exchangers), food showcases, etc. In addition, there is a metal material processed article excellent in design property that exhibits an excellent aesthetic appearance by performing a chemical coloring treatment. These may be finished products or parts. Specifically, construction materials (e.g., nails, bolts, nuts, screws, files, wire rods, pipes, steel plates, hose joints, keyhole caps, etc.), daily necessities (e.g., mugs, spoons, forks, eyeglass frames, bookmarks, Baskets, chairs, desks, thermos bottles, toys, nail clippers, etc.), plumbing supplies (sinks, bathtubs, system kitchens, draining plates, washing baskets, etc.), clothing accessories (hooks, buttons, hairpins, buckles, fasteners, medals, etc.) , mechanical parts (chains, friction rings, manifolds, car bodies, bicycle frames, wheelchair frames, etc.), and other advertising panels.
The processed metal material may be a metal material that has undergone a chemical coloring treatment, or a metal material that has been processed and then subjected to a chemical coloring treatment.

(3) Sandblasting In sandblasting, a projecting material (sometimes referred to as an abrasive or an abrasive) is made to collide with an object to perform surface treatment. There are mechanical, pneumatic, and wet methods for projecting the projectile material. The pneumatic type includes a vacuum type that carries the projection material by negative pressure and a direct pressure type that carries the projection material by positive pressure.
In the sandblasting process, the blasting material used in this process for efficiently processing the surface of the metal material should have a hardness higher than that of the metal material (for example, Mohs hardness of 6 or more, more preferably 8 or more). It is preferred to use inorganic materials, preferably angular particles such as spheres or polygons, particularly angular particles. Specific examples include glass beads, zirconia particles, steel grids, alumina particles, silica particles, silicon carbide particles and the like.

The particle size (number) of the shot material is preferably #70 to #800, more preferably #90 to #500. If the particle size is smaller than #70, the particle size is large, the haze of the treated product becomes high, and the visibility tends to decrease. This is because particles with a particle size exceeding #800 tend to be inefficient in sandblasting due to their small particle size.

The projection pressure when the projection material is projected onto the metal material is preferably 0.05 to 1 MPa, more preferably 0.1 to 0.5 MPa. If the blasting pressure is less than 0.05, the sandblasting process becomes inefficient due to the low blasting pressure, and uneven surfaces with variations are likely to be formed. When the blasting pressure exceeds 1 MPa, the collision energy when the blasting material reaches the surface of the metal material tends to increase, the shape of the unevenness on the treated surface becomes large, and the color tone of the surface of the metal material that has undergone chemical coloring treatment deteriorates. Because it becomes.

When the projection material is projected onto the metal material, the projection angle is preferably 10 to 90 degrees when the surface of the metal material is assumed to be 0 degrees. This is because if the angle is less than 10°, the sandblasting process tends to be inefficient. Considering efficiency, the projection angle is preferably 15° or more, more preferably 20° or more.

The projection distance (the distance from the projection start position to the surface of the metal plate) when the projection material is projected onto the surface of the metal material is preferably 5 to 300 mm, more preferably 10 to 250 mm. If it is less than 1 mm, the impact energy increases, the haze on the treated surface of the metal material increases, and the visibility decreases. This is because sandblasting tends to become inefficient when the thickness exceeds 400 mm.

When the projection material is projected onto the surface of the metal material, the amount of projection is preferably 50 to 300 g/min, more preferably 100 to 200 g/min. If it is less than 50 g/min, the sandblasting process tends to be inefficient, and if it exceeds 300 g/min, unevenness that can be visually confirmed tends to occur in the processed product.

(4) Electrolytic Cleaning Treatment Electrolytic cleaning is a cleaning method in which an object to be treated is electrolyzed as an anode or a cathode in an electrolytic solution. Dirt is removed by the stirring action of the gas generated from the surface of the object to be treated. The anodic electrolytic cleaning method, in which the object to be treated is used as an anode, has the effect of destroying the organic stains through an oxidation reaction caused by the oxygen gas generated on the surface of the object to be treated. The anodic electrolytic cleaning method is resistant to impurities and can also prevent hydrogen embrittlement. In the cathodic electrolytic cleaning method in which the object to be treated is used as a cathode, hydrogen gas is generated on the surface of the object to be treated. When electrolyzed at the same current density, the amount of gas generated is twice that of the anodic electrolytic cleaning method, and the cleaning performance is high due to the stirring effect of the gas. Materials that pose a problem of hydrogen embrittlement must be post-processed to remove hydrogen.
In the present invention, an anodic electrolytic cleaning method using the object to be treated as an anode is preferred.

Electrolytic cleaning is generally carried out in an alkaline aqueous solution, but there is also electrolytic acid cleaning carried out in an acid aqueous solution. Electrolytic acid cleaning can utilize the dissolving power of acid for scale and rust, the stirring action of gases (oxygen and hydrogen) generated by electrolysis, and the reducing power of hydrogen. Electrolytic acid cleaning is used only for steel-based materials.
Electrolytic acid cleaning is preferred in the present invention.

Electrolytic solutions used for electrolytic cleaning include inorganic acid salts (carbonates, silicates, phosphates) that ensure pH by buffering, emulsifying and dispersing dirt, softening water hardness, and wetting and moistening dirt components. Surfactants having permeation and anti-redeposition actions, and chelating agents having metal ion trapping and oxide film removal actions can be added.

The conditions of electrolytic acid cleaning (electrolytic solution composition, treatment temperature, treatment time, current density) can be suitably selected depending on the object to be treated. Generally, the treatment temperature is 15-50° C., the treatment time is 30-180 min, and the current density is 3-10 A/dm ² .

(5) Electropolishing treatment Electropolishing is performed by applying a direct current to the metal in an electropolishing solution suitable for the metal, and dissolving the convex portions of the metal surface with fine unevenness to smooth and gloss the metal surface. It is a polishing method that It is possible to remove dirt, foreign matter, and a work-affected layer generated by physical polishing such as buffing.

The electropolishing liquid is preferably a single or mixed acidic aqueous solution of hydrogen peroxide, glacial butyric acid, phosphoric acid, sulfuric acid, nitric acid, chromic acid, sodium dichromate, and the like. In addition, ethylene glycol monoethyl ether, ethylene glycol monobutyl ester and glycerin can be used as additives. These additives have the effect of stabilizing the electrolytic solution and widening the range of appropriate electrolysis against changes in concentration, changes over time, and deterioration due to use.

Specifically, in an electrolytic solution consisting of 40 to 80 vol% phosphoric acid, 5 to 30 vol% sulfuric acid, 15 to 20 vol% water, and 0 to 35 vol% ethylene glycol, 40 to 70 ° C., 3 to 10 min, direct current (10 to 30 V, 3-60 A/dm ³ ).

(6) Color-developing treatment By color-developing treatment, an ultra-thin light-transmitting oxide film (hereinafter referred to as "color-developing film") is formed on the surface of the metal material that has undergone sandblasting and electropolishing. The metal material develops color by utilizing the light interference effect of the color-developing film. It is possible to express a tasteful color tone that reflects the beauty of the base surface of the metal material. A stainless processed product will be described below as a specific example.

(6-1) Color-developing treatment As a color-developing method, a stainless processed product was electrolyzed with a direct current in a mixed solution of sulfuric acid and chromic acid (hereinafter referred to as "color-developing solution"), and then immersed in an aqueous solution. A so-called inco method is employed in which a desired colored film is formed by a potential difference with a reference electrode (see JP-A-48-011243).
When the thickness of the coloring film is optically obtained from the light interference peak, the thickness of the coloring film formed on the surface of the stainless processed product is proportional to the potential difference between the anode and the reference electrode (hereinafter referred to as "coloring potential"). do. The values are 6 mV (blue: 90 nm), 13 mV (gold: 150 nm), 16 mV (red: 180 nm), and 19.5 mV (green: 220 nm) in each color tone (Takeshi Takeuchi, Jitsugyo Onsen Gijutsu, Vol. 33, 11 No., 1986). The thickness of this colored film is significantly larger than the thickness (1 to 3 nm) of the passive film formed on the stainless processed product.
Therefore, it is important to control the thickness of the colored film because the color unevenness in the colored stainless processed product is caused by the variation in the thickness of the colored film.

(6-2) Color-developing film By lowering the generation rate of the color-developing film, it is possible to moderate the expression of color tone and reduce color unevenness. This is because the thickness of the coloring film formed on the surface of the stainless processed product correlates with the coloring potential.
The mixing ratio of sulfuric acid and chromic acid (chromic acid/sulfuric acid) in the coloring solution is preferably 15-30 wt/vl % chromic acid and 40-50 wt/vl % sulfuric acid. This is because by reducing the concentration of chromic acid, the rate of formation of the colored film can be lowered, and the thickness of the formed colored film can be precisely controlled.
The generation speed of the colored film can be controlled by the coloring potential speed (mV/sec). The coloring potential speed is 0.02 to 0.08 mV/sec, preferably 0.050 to 0.065 mV/sec. This is because if the coloring potential speed is less than 0.02 mV/sec, the formation of the coloring film is delayed and the productivity is lowered. This is because if the coloring potential speed exceeds 0.08 mV/sec, the thickness of the formed coloring film becomes uneven, resulting in unnatural color tone and color unevenness.

(6-3) Manganese Ions Manganese ions (Mn ²⁺ ) can be added in order to compensate for the rate of formation of a colored film as the concentration of chromic acid in the coloring solution decreases. Manganese salts used in the coloring solution include manganese hydrochloride (MnCl ₂ ), manganese sulfate (MnSO ₄ ), manganese nitrate (Mn(NO ₃ ) ₂ ) and the like, and one or more of these may be used. can be done. The manganese ion (Mn ²⁺ ) concentration in the coloring solution is preferably 0.5 to 300 mmol/L, more preferably 5 to 150 mmol/L. When the manganese ion (Mn ²⁺ ) concentration is less than 0.5 mmol/L, there is no effect of promoting the formation of the colored film, and when the manganese ion (Mn ²⁺ ) concentration exceeds 300 mmol/L, an insoluble portion remains and the colored film is formed. This is because it affects generation.

(7) Hardening Treatment The stainless steel product on which the colored film is formed by oxidation is electrolytically treated to harden the colored film. In this hardening treatment, the colored film is hardened by filling the pores of the colored film with chromium by electrolysis in a mixed solution of phosphoric acid and chromic acid (hardening treatment is applied to the surface of the stainless processed product to give it a metallic luster). It is intended to give color development of color tone.

(8) Evaluation Both solid and colored stainless processed products were visually evaluated for anti-fingerprint visibility. In addition, the "60 degree specular glossiness [Gs (60 degrees)]" was also evaluated for the colored stainless processed products.

(8-1) Anti-Fingerprint Visibility The anti-fingerprint visibility was evaluated visually. Specifically, a finger (thumb) of a human hand was pressed against the test piece for 3 seconds, and the degree of conspicuousness of the fingerprint was visually observed, and expressed according to the following criteria.
・Fingerprints that cannot be identified at all 〇 ・Fingerprints that can be clearly identified ×

(8-2) 60 degree specular gloss (Gs60°)
A 60° specular gloss method (Gs60°) was used to express the specular state of the surface of the test product as a numerical value. The method for measuring the 60° specular glossiness is described in JIS Z8741 "Specular glossiness--Measuring method", and the glossiness of the surface of the colored stainless processed product was measured based on this description. A gloss meter (Gloss meter U manufactured by Toyo Seiki Seisakusho) was used as a measuring device.

Next, an embodiment exhibiting the effects of the present invention will be shown as an example. Table 1 shows the summary.

<Example 1>
(1) Sandblasting A test piece (30 × 30 × 1 mmt) was placed in a sandblasting device (not shown), and the main surface of the test piece was sandblasted under the following conditions to produce a sandblasted product 1. .
[Sandblasting conditions]
・Abrasive glass powder (#60)
・Projection pressure 0.4MPa
・Projection angle 40°
・Projection time 15 sec
・Projection distance 50mm
・Amount of projection 450g/min

(2) Electrolytic Cleaning Treatment The sandblasted product 1 was subjected to an electrolytic cleaning treatment under the following conditions to produce an electrolytically cleaned product 1 .
[Electrolytic cleaning treatment conditions]
・Electrolytic cleaning liquid composition Sodium sulfite 100 g/L, polyoxyethylene octylphenyl ether 10 ml/L, polyoxyethylene alkyl ether 1 ml/L, sodium lauryl sulfate 2 ml/L
・Processing temperature 45℃
・Processing time 4min
・Current density 8.0A/dm ²
・Ultrasonic treatment 1min Standard frequency 24.5 to 27.5kHz

(3) Electropolishing Treatment Electrolytic polishing treatment was performed on the electrolytically cleaned product 1 under the following conditions to prepare an electrolytically polished product 1 (hereinafter referred to as "Example 1 product").
[Conditions of electropolishing treatment]
・Electropolishing liquid composition Phosphoric acid 700ml/L, sulfuric acid 200ml/L, ethylene glycol 0.2ml/L
・Processing temperature 70℃
・Processing time 8min
・Current density 8.0A/dm ²

<Example 2>
Electropolished product 2 (hereinafter referred to as "Example 2 product") was produced in the same manner as in Example 1, except that glass beads (#200) were used as the abrasive for sandblasting.

<Example 3>
An electropolished product 3 (hereinafter referred to as "Example 3 product") was produced in the same manner as in Example 1, except that zircon (#60) was used as the abrasive for sandblasting.

<Example 4>
(1) Sandblasting A test piece (30 × 30 × 1 mmt) was placed in a sandblasting device (not shown), and the main surface of the test piece was sandblasted under the following conditions to prepare a sandblasted product 4. .
[Sandblasting conditions]
・Abrasive glass powder (#60)
・Projection pressure 0.4MPa
・Projection angle 40°
・Projection time 15 sec
・Projection distance 50mm
・Amount of projection 450g/min

(2) Electrolytic Cleaning Treatment The sandblasted product 1 was subjected to an electrolytic cleaning treatment under the following conditions to prepare an electrolytically cleaned product 4 .
[Electrolytic cleaning treatment conditions]
・Electrolytic cleaning liquid composition Sodium sulfite 100 g/L, polyoxyethylene octylphenyl ether 10 ml/L, polyoxyethylene alkyl ether 1 ml/L, sodium lauryl sulfate 2 ml/L
・Processing temperature 45℃
・Processing time 4min
・Current density 8.0A/dm ²
・Ultrasonic treatment 1min Standard frequency 24.5 to 27.5kHz

(3) Electrolytic Polishing Treatment Electropolishing treatment was performed on the electrolytically cleaned product 1 under the following conditions to prepare an electrolytically polished product 4 .
[Conditions of electropolishing treatment]
・Electropolishing liquid composition Phosphoric acid 700ml/L, sulfuric acid 200ml/L, ethylene glycol 0.2ml/L
・Processing temperature 70℃
・Processing time 8min
・Current density 8.0A/dm ²

(4) Color development treatment Electropolishing product 4 was subjected to color development treatment under the following conditions to prepare color development product 4 .
[Color development processing conditions]
・Coloring solution composition chromium oxide 250g/L, sulfuric acid 500g/L
・Processing temperature 80℃
・Processing time 8min
・Color development potential 8mV

(5) Curing treatment Coloring treated product 4 was subjected to curing treatment under the following conditions to prepare cured product 4 (hereinafter referred to as "Example 4 product").
[Curing conditions]
・Hardening liquid composition chromium oxide 250g/L, phosphoric acid 2.5g/L
・Processing temperature 25℃
・Processing time 10min
・Current density 0.5A/dm ²

<Example 5>
Hardened product 5 (hereinafter referred to as “Example 5 product”) was produced in the same manner as in Example 4, except that glass beads (#200) were used as the abrasive for sandblasting.

<Example 6>
A hardened product 6 (hereinafter referred to as “Example 6 product”) was produced in the same manner as in Example 4, except that zircon (#60) was used as the abrasive for sandblasting.

<Comparative Example 1>
(1) Sandblasting A test piece (30 × 30 × 1 mmt) is placed in a sandblasting device (not shown), and the main surface of the test piece is sandblasted under the following conditions (same as in Example 1), Comparative example 1 product was produced.
[Sandblasting conditions]
・Abrasive glass beads (#200)
・Projection pressure 0.4MPa
・Projection angle 40°
・Projection time 15 sec
・Projection distance 50mm
・Amount of projection 450g/min

<Comparative Example 2>
An untreated test piece (30×30×1 mmt) was used as Comparative Example 2.

<Comparative Example 3>
(1) Sandblasting A test piece (30 × 30 × 1 mmt) is placed in a sandblasting device (not shown), and the main surface of the test piece is sandblasted under the following conditions (same as in Example 1), A sandblasted product 7 was produced.
[Sandblasting conditions]
・Abrasive glass beads (#200)
・Projection pressure 0.4MPa
・Projection angle 40°
・Projection time 15 sec
・Projection distance 50mm
・Amount of projection 450g/min

(2) Color-developing treatment The sandblasted product 7 was subjected to color-developing treatment under the following conditions (same as in Example 5) to prepare a color-developing product 7 .
[Color development processing conditions]
・Coloring solution composition chromium oxide 250g/L, sulfuric acid 500g/L
・Processing temperature 80℃
・Processing time 8min
・Color development potential 8mV

(3) Curing treatment Coloring treated product 7 was subjected to curing treatment under the following conditions (same as Example 5) to prepare cured product 7 (hereinafter referred to as "comparative example 3 product").
[Curing conditions]
・Hardening liquid composition chromium oxide 250g/L, phosphoric acid 2.5g/L
・Processing temperature 25℃
・Processing time 10min
・Current density 0.5A/dm ²

<Comparative Example 4>
(1) Color-developing treatment A test piece (30 x 30 x 1 mmt) was subjected to color-developing treatment under the following conditions (same as in Example 5) to prepare a color-developing product 8 .
[Color development processing conditions]
・Coloring solution composition chromium oxide 250g/L, sulfuric acid 500g/L
・Processing temperature 80℃
・Processing time 8min
・Color development potential 8mV

(3) Curing treatment The coloring treated product 8 was subjected to a curing treatment under the following conditions (same as in Example 5) to prepare a cured product 8 (hereinafter referred to as "comparative example 4 product").
[Curing conditions]
・Hardening liquid composition chromium oxide 250g/L, phosphoric acid 2.5g/L
・Processing temperature 25℃
・Processing time 10min
・Current density 0.5A/dm ²
Hardened product 5 (hereinafter referred to as "Example 5 product") was produced in the same manner as in Example 4, except that glass beads (#200) were used as the abrasive.

<Evaluation>
(1) Evaluation of 60-degree specular gloss (Gs60°) For each of Example 4, Example 5, Example 6, Comparative Example 3, and Comparative Example 4, 60-degree specular gloss (Gs60°) was measured at an incident angle of 60 degrees using a JIS Z8741 gloss meter (Toyo Seiki Seisakusho Gloss Meter U). Glossiness is as shown in Table 1.
FIG. 3 shows the states of light reflection of Example 4, Example 5, Example 6, Comparative Example 3, and Comparative Example 4. From the 60-degree specular glossiness and light reflection, the example products are superior in light scattering property to the comparative example products.

(2) Anti-fingerprint evaluation A finger to which an artificial fingerprint solution (manufactured by Isekyu Co., Ltd., conforming to Annex 4 of JIS C9606) is attached, is subjected to Example 1 to Example 6 and Comparative Example 1 to A fingerprint was adhered by pressing against the 4 products of Comparative Example. This was visually observed and evaluated according to the following criteria. Table 1 shows the evaluation results. All of the products of the examples had a fingerprint resistance of "O".
◯: No trace of fingerprints is visible.
×: Traces of fingerprints can be seen

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a stainless processed product having excellent anti-fingerprint properties.

Claims (2)

a sandblasting step of forming an uneven surface on the surface of the stainless steel workpiece by blowing a mixture of an abrasive and compressed air onto the surface of the stainless steel workpiece;
an electrolytic cleaning step of anodic electrolytic cleaning of the sandblasted stainless processed product in an electrolytic cleaning agent using the stainless steel processed product as an anode;
an electrolytic polishing treatment step of electrolytically polishing the surface of the stainless processed product that has been electrolytically cleaned;
A method for manufacturing a stainless processed product having an uneven surface on the surface, characterized by comprising: a sandblasting step of forming an uneven surface on the surface of the stainless steel workpiece by blowing a mixture of an abrasive and compressed air onto the surface of the stainless steel workpiece;
an electrolytic cleaning step of anodic electrolytic cleaning of the sandblasted stainless processed product in an electrolytic cleaning agent using the stainless steel processed product as an anode;
an electrolytic polishing treatment step of electrolytically polishing the surface of the stainless processed product that has been electrolytically washed;
A coloring treatment step of forming a colored film on the surface of the stainless steel processed product by immersing the electropolished stainless steel processed product in a coloring treatment liquid consisting of a mixed solution of chromic acid and sulfuric acid;
A hardening treatment step of immersing the stainless processed product that has undergone the coloring treatment in a hardening treatment liquid consisting of a mixed solution of chromic acid and phosphoric acid to harden the colored film formed in the coloring treatment step;
A method for producing a chemically colored stainless processed product having an uneven surface formed on the surface, characterized by comprising:

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