HK1058164A1

HK1058164A1 - Coating on metal surface and the method to form the coating

Info

Publication number: HK1058164A1
Application number: HK04100955A
Authority: HK
Inventors: Osawa Hiroshi; Kanai Hiroshi
Original assignee: Nippon Steel Corporation
Priority date: 2002-02-06
Filing date: 2004-02-12
Publication date: 2004-05-07
Also published as: CN1265895C; JP3881558B2; CN1436607A; JP2003226983A

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic surface coating which can improve fingerprint resistance while maintaining a variety of designing, and to provide a method of forming the same. <P>SOLUTION: The metallic surface coating is obtained by forming a coating thin film layer essentially consisting of a transparent resin having a viscosity of 10 to 10<SP>12</SP>Pa s on a metallic surface. The coating weight of the coating thin film layer is 0.01 to 1.0 g/m<SP>2</SP>. The resin contains at least one kind selected from resins, organic compounds and organic-inorganic compounds containing the atoms of one or more kinds of elements selected from Si, B, Ti, F, Ge and Se. A layer essentially consisting of titanium, a titanium alloy or a titanium- containing compound is formed on the metallic surface, and the above coating thin film layer is formed thereon. In the method of forming the above metallic surface coating, a metallic surface is coated with a liquid containing a transparent resin having a viscosity of 10 to 10<SP>12</SP>Pa s, and, after that, the coated liquid is wiped away. <P>COPYRIGHT: (C)2003,JPO

Description

Metal surface coating and method of forming the same

Technical Field

The present invention relates to a metal surface coating layer capable of providing a metal surface represented by a titanium plate, maintaining the surface properties of a metal specimen visually obtainable, and providing a metal surface having high fingerprint resistance, and a method for forming the same.

Background

Painting is generally performed on the surface of the metal product. General metal products, such as steel products, must be painted to prevent rust on the surface. On the other hand, stainless steel products, titanium products, chrome-plated products, and the like do not require any concern about rust, and therefore, a metal surface is often used as it is without painting on the surface. The metal surface has a unique metallic luster, and the appearance thereof can be changed by performing mirror finishing or matte finishing, and can visually induce aesthetic sense. In addition, since the metal surface is hard, a unique hardness feeling which is not present in the surface of the resin coating layer can be produced.

Particularly, a strong and stable titanium oxide film is present on the surface of titanium, and the color tone can be controlled by adjusting the thickness of the titanium oxide film, thereby exhibiting a unique texture. In titanium products used in the field of construction materials, the thickness of a titanium oxide coating film on the surface is controlled by anodic oxidation, and titanium sheets of various color tones are used as colored titanium.

The surface properties peculiar to the metal surface which can be visually obtained as described above are referred to as the appearance of the metal surface.

As a problem of a metal product having an unpainted metal surface, there is a problem of fingerprint adhesion. When a fingerprint is attached to a metal surface, the fingerprint is conspicuous and cannot be removed even by wiping, and the fingerprint easily remains. In particular, in titanium products, an optical interference color produced by an oxide coating film having a high refractive index on the surface gives a unique texture, and the difference between the refractive index of the film and that of grease which is a main component of fingerprints is large, so that the adhered fingerprints are remarkable. In a metal surface having a matte finish, fingerprint oil or fat adhering to the metal surface by wiping tends to remain in the wrinkle grooves, making wiping difficult.

A method of forming a transparent coating film on a metal surface using an inorganic material or an organic material is known as a method of forming a transparent coating film using an inorganic material or an organic material, as a means for improving fingerprint resistance, which means that attached fingerprints are not conspicuous and can be easily removed by wiping. Since it is transparent, gloss and color of the metal surface can be expressed, and since the refractive index of the transparent cover film and the refractive index of the grease constituting the fingerprint are close, the fingerprint may not be conspicuous.

In the transparent coating layer in which the metal surface is covered with a transparent coating film, spray coating, roll coating or brush coating is used as a coating method, and the layer may have a thickness of 1 to 30 μm. Although transparent, if a coating film layer having such a thickness is present on the metal surface, the texture peculiar to the metal surface is impaired, and the commercial value as the metal surface tends to be remarkably lowered. In addition, since the transparent coating layer has a low hardness as compared with metals, the sense of hardness peculiar to the metal surface is lost.

In particular, in the titanium product, since the optical interference color produced by the high refractive index titanium oxide coating film present on the surface exhibits unique appearance, the absorption wavelength in the visible light region is changed by the transparent coating film covering layer, and the surface appearance of the titanium product is significantly impaired. For example, in the field of building materials, colored titanium produced by anodizing, which is the first one, has been discussed as having surface appearance, but titanium applied with a transparent coating layer as a fingerprint countermeasure may not have an appearance consistent with the intention of the builder and may not be used.

The cover of the clear coat layer was coated and cured in a factory. When an inorganic material is used as a transparent coating layer, the inorganic material generally lacks flexibility of the coating film itself, and there is a problem that the processing of the coated metal product is difficult. On the other hand, when an organic material is used as a transparent coating layer, the organic material varies to some extent, and the active catalytic action of the oxide coating film on the titanium surface is decomposed by ultraviolet rays, resulting in a problem of limited lifetime. Further, there is a problem that reprocessing of the top layer of the clear coat layer after application, such as peeling, coating, and curing, is not easy, regardless of whether the material is an organic material or an inorganic material.

Disclosure of Invention

The present invention has as its 1 st object to provide a metal surface coating layer which can maintain the appearance of the metal surface and improve fingerprint resistance, and a method for forming the same. The object of the invention 2 is to provide a metal surface coating which can be processed after forming a coating film, can form a coating film which is resistant to ultraviolet deterioration and has a long life, and can be peeled off and recoated after forming the coating film.

The present invention is directed to solving the above problems, and the gist thereof is as follows.

(1) A metal surface coating is characterized in that 10-10 parts of coating is formed on the surface of metal⁶A covering film layer mainly composed of a thermoplastic resin having a viscosity of Pa · s.

(2) The metal surface coating layer according to the above (1), wherein the amount of the coating film layer is 0.01 to 1.0g/m²。

(3) The metal surface coating layer according to the above (1), wherein the resin contains at least one of a resin, an organic compound, and an organic-inorganic composite, the resin containing one or more atoms selected from Si, B, Ti, F, Ge, and Se.

(4) The metal surface coating layer according to the above (1), wherein the coating thin film layer contains a wax component.

(5) The metal surface layer according to the above (1), wherein a layer containing titanium, a titanium alloy or a titanium-containing compound as a main component is formed on the metal surface, and the thin coating film layer is formed thereon.

(6) The metal surface coating layer according to the above (1), wherein the metal surface has a flatness Ra of 4 to 40 μm.

(7) A metal product having the metal surface coating layer according to any one of the above (1) to (6).

(8) The method for forming a metal surface coating layer according to any one of the above (1) to (6), wherein the metal surface coating layer contains a metal having a surface roughness of 10 to 10%⁶A liquid of a thermoplastic resin of Pa · s viscosity, and then wiping the applied liquid.

(9) The method for treating a metal product according to item (7), wherein the metal product is coated on a surface of the metal product, the surface containing the metal product having a surface roughness of 10 to 10%⁶A liquid of a thermoplastic resin of Pa · s viscosity, and then wiping the applied liquid.

Now, in the transparent metal surface coating called transparent film, it is a matter of course that the cover layer is neither gas nor liquid, and is in the category of solid. The main component of the covering layer of the present invention is 10 to 10¹²The transparent resin having a viscosity of pas has the greatest characteristic. The viscosity is 10-10¹²When Pa.s or less, the resin has fluidity, and the transparent resin is liquid as compared with the resin.

Since the main component of the cover layer has fluidity, the cover layer can be easily formed into a thin film by wiping at the time of or after formation. By forming a thin film, particularly with a coverage of 1.0g/m²Or a film having a visually-obtained metal surface property substantially equal to that of a metal surface without a resin coating film, and capable of securing the appearance of the metal surface. On the other hand, the resin coating layer is provided, and the refractive index of the resin coating layer is close to the refractive index of the grease constituting the fingerprint, so that the fingerprint can be made inconspicuous. That is, both the appearance and fingerprint resistance of the metal can be provided.

Since the main component of the coating layer has fluidity, the resin layer flows easily when wiped off after the coating layer is formed. Therefore, wiping off the fingerprint from the portion where the fingerprint is attached has an advantage that the grease constituting the fingerprint and the resin layer flow together, and the fingerprint can be easily removed.

In the case of conventional coatings having a thickness such as a clear coating, the coating is flowableThe coating layer is dropped after the construction to cause non-uniformity and the appearance is deteriorated, but the coating layer is formed into a thin film in the present invention, if it is 10 to 10¹²The viscosity in the range of Pa · s does not cause dripping. That is, the coating layer having fluidity can be formed for the first time by forming the thin film.

In the present invention, the resin means a polymer or oligomer obtained by polymerizing an organic compound, and has a function of adhering to a substrate or a function of holding other components blended in the resin. Contains substances copolymerized or added with inorganic materials. Examples of the resin that can be used in the present invention include known resins, mixtures thereof, and copolymers thereof, such as polyolefins, polyesters, polypropylenes, epoxies, polysiloxanes, polyurethanes, fluorines, polyamides, and acetals. The molecular weights of the resins are not particularly limited if their viscosities are within the scope of the present invention. The transparent resin of the present invention means that the metal surface as a substrate is not only colorless and transparent but also colored and transparent, which can be seen after the surface coating of the present invention is applied. In order to ensure the appearance of the metal, it is preferably colorless and transparent. Even if the raw material resin block before coating is opaque, it is referred to as a transparent resin as long as it is transparent when it is used as a film after coating. When the surface is covered, if the color or appearance of the substrate is not visible at all, the substrate is judged to be opaque.

The viscosity of the transparent resin constituting the main component of the covering film layer of the present invention is required to be 10 to 10¹²Pa · s. When the viscosity is less than 10Pa · s, even if the coating layer is formed as a thin film, the fluidity of the resin to be applied is too high, the coating film layer moves downward under the influence of gravity, and the appearance becomes uneven in film thickness, and further, sufficient fingerprint resistance cannot be obtained in a portion having an extremely thin film thickness, which is not preferable. On the other hand, if the viscosity exceeds 10¹²Pa · s is difficult to apply uniformly when forming a resin coating film, to move the resin during a wiping step to cause unevenness, or to coat the resin on fine uneven portions of the metal surface, and therefore, insufficient coverage is likely to occurA portion exhibiting fingerprint resistance. The upper limit of the viscosity is more preferably 10⁶Pa · s, particularly preferably 10⁴Pa·s。

The viscosity defined in the present invention basically means the viscosity at the temperature of the metal product to which the metal surface coating is applied. The term "viscosity at ordinary temperature", that is, at 20 ℃ is used in the ordinary sense.

The viscosity of the resin is measured at 10-10⁶The Pa · s range is a method of measuring stress by applying dynamic strain to a resin and calculating a viscosity coefficient, that is, viscosity from the stress and the strain rate. Specifically, レオメトリク, for example, can be used_ッス·サイエンテ_ィフ_ィ _ック, エフ, イ -company rheometer. As the frequency of applying strain, 10 was used^-2Low frequency of rad/s. Further, the viscosity exceeds 10⁶Pa · s, the elongational viscosity of 2-axis was determined using an elongational rheometer using a lubricating squeeze flow, and this value was used. The details of this method are described in pages 250 to 251 of "lecture rheology" (journal of Polymer journal, 1 st edition 1992) compiled by the society for rheology of Japan. Specifically, レオメトリク, for example, may be used_ッス·サイエンテ_ィフ_ィ _ッThe measurement was carried out by an ARES multifunctional viscoelasticity measurement system of ク, エフ, イ.

The preferable coverage of the covering film layer is 0.01-1.0 g/m². The coverage is less than 0.01g/m²When the coating layer is too thin, the effect of improving the fingerprint resistance is reduced. Further, the coverage exceeds 1.0g/m²In this case, the surface properties visually recognized change due to the resin coating, and the appearance of the metal product becomes a problem. Further, if the amount of adhesion is too large, the resin having fluidity flows off, and the appearance may be uneven, which is not preferable. Further, if the amount of the coating is large, the coating layer may be deteriorated by ultraviolet rays and the workability may be deteriorated. The covering amount of the covering film layer is 0.03-0.30 g/m²Better results can be obtained.

Since the covering thin film layer of the present invention is formed by a resin having fluidity, it is possible to easily process a metal after the covering. If necessary, the thin cover film layer applied to the metal surface may be peeled off and the thin cover film layer may be formed again on the metal surface. As a method for forming the thin film layer, a method described later can be used.

The resin in the cover film layer of the present invention is preferably a thermoplastic resin. The coating film layer of the present invention formed on the metal surface can be deteriorated with time by outdoor light, light of a fluorescent lamp, heat applied from the outside, or a photocatalytic action when the metal surface is titanium. The deterioration may reduce the fingerprint resistance, and in this case, the deteriorated coating thin film layer is removed and the metal surface coating layer may be formed again according to the present invention. If the resin of the cover layer is not a thermoplastic resin, that is, a thermosetting resin, the resin may become hard with time and, when the deteriorated cover layer is to be removed, the cover layer may not be removed completely and remain, and the effect of improving the fingerprint resistance of the re-formed cover layer may be reduced. On the other hand, if the resin in the cover layer is a thermoplastic resin, the cover layer can be easily removed, and the fingerprint resistance of the re-formed cover film can be sufficiently exhibited. Further, since the thermoplastic resin does not cause curing of the cover layer due to change with time, the cover layer flows when the attached fingerprint is wiped off, and the fingerprint can be easily removed. Furthermore, in the case of a thermosetting resin, when a uniform film is to be formed by wiping, the temperature of the resin rises due to wiping, and the resin is hard to be formed into a uniform film by curing, but in the case of a thermoplastic resin, even if the temperature of the resin rises during wiping, the fluidity is not lost, and a sufficiently uniform film can be formed.

As described above, the coating thin film layer formed on the metal surface may deteriorate with time due to outdoor light, light from a fluorescent lamp, heat applied from the outside, or a photocatalytic effect when the metal surface is titanium. When the coating film contains a silane-based compound containing an Si atom, for example, a silicone resin, the durability of the resin can be improved against the decomposition by the active catalysis of the ultraviolet ray or the titanium oxide film. However, when a silane compound is contained in a resin coating film layer having a conventional thickness, the silane compound cannot be added to the resin layer for coating the metal surface because of the problem of the coating film layer dropping. In the present invention, since the thin coating film layer is extremely thin, the coating film layer does not sag even when the silane compound is contained in the coating layer. Therefore, in the present invention, the silane compound can be contained in the cover thin film layer, whereby durability against the decomposition action of the ultraviolet ray or the titanium oxide film by the active catalyst can be provided, that is, the weather resistance of the cover thin film layer can be improved.

The component for improving the weatherability may be at least one of a resin containing one or more atoms of Si, B, Ti, F, Ge, Se (hereinafter referred to as "Si or the like"), an organic compound, and an organic-inorganic composite, including a Si atom-containing resin in the resin constituting the cover thin film layer. As these resins and the like, transparent materials are preferably used. These elements may be added in the form of, for example, compounds having the form-Si-O-, -B-O-, -Ti-O-, -Ge-O-, -O-Se-, or-C-F-, -C-Si-, and the like. These bonds have higher bond energies than those of the bonds such as-C-, -C-H-, -C-O-and the like which are generally contained in organic compounds, and are difficult to decompose by stimulation such as heat or ultraviolet light, and thus have the effect of improving the durability of the resin layer. These may be added in the form of organic-inorganic composite compounds such as silicone resins, fluorine resins, boron titanate compounds, various silane coupling agents, various titanium coupling agents, tetraethoxysilane, ethoxytitanium, germanic acid compounds, and selenic acid compounds, or may be used as resins having such a structure in the molecule.

The content of atoms such as Si is not particularly limited, and depends on the viscosity of the coating agent. That is, when the viscosity of the compound containing an atom such as Si is within the range of the present invention, the compound containing an atom such as Si may be covered as a transparent resin. The compound containing an atom such as Si may be added to the transparent resin in a range where the viscosity of the transparent resin is not outside the range specified in the present invention. In order to improve durability, the content of atoms such as Si is preferably 10% or more in the coating film covering the metal surface.

The covering film layer of the present invention preferably contains a wax component. The wax component is referred to as a component that improves the lubricity of the surface. By containing the wax component, the effect of good lubricity of the surface and easy stretching and uniform coating can be obtained when wiping is performed to form a thin coating film layer by stretching the surface of the metal. In addition, when the surface of the film is wiped to remove fingerprints attached to the surface, the surface of the film is smooth, and the film has the effect of easily wiping fingerprints. Further, the hydrophobic property of the metal surface coating layer is also improved.

Known substances can be used as wax components. Examples of the organic wax include olefins such as polyethylene and polypropylene, organic waxes such as carnauba, polyesters, silicones and fluorine, and compounds such as molybdenum disulfide and zinc stearate. The content of the wax component in the coating film layer is not particularly limited, and depends on the viscosity of the coating agent. That is, the viscosity of the transparent resin to which the wax is added may be added within a range not outside the range specified in the present invention. If the wax component is not contained at all, the frictional resistance at the time of wiping after application increases, workability is poor, and the transparent resin component hardly enters into fine irregularities on the metal surface, so that it is preferable that the transparent resin contains 1% or more of the wax component. In addition, if the wax component is too much, the retention of the transparent resin on the metal surface is deteriorated, and therefore, the content of the wax component in the coating film covering the metal surface is preferably 80% or less.

In the cover film layer of the present invention, in addition to the above components, known additives such as a viscosity modifier, an antifoaming agent, and a dispersion aid may be added within a range in which transparency can be secured.

The metal surface coating of the present invention can be widely used in the case where it is desired to produce the properties of the metal surface as it is without forming a thick coating film such as a paint on the surface. Therefore, the metal surface coating of the present invention can be applied to all metal surfaces of the subject metal stainless steel, titanium, copper, aluminum, steel, chrome-plated steel, and the like. Any treatment may be applied to the metal surface by a known method such as plating, vapor deposition, thermal spraying, C, painting, or cladding. The present invention is particularly excellent for the treatment of metals having excellent surface appearance and poor fingerprint resistance, such as titanium and stainless steel. Similarly, when a layer containing titanium, a titanium alloy or a compound containing titanium as a main component is formed on the surface of various metals, good results can be obtained if the thin coating film layer of the present invention is formed thereon.

Since a strong and stable titanium oxide film is formed on the surface of titanium or a titanium alloy, the titanium does not rust even if it is not painted or plated. Further, a titanium oxide film having a controlled thickness is formed on the surface of titanium by an anodic oxidation method, and the colored titanium having a unique color is used for applications such as building materials. The appearance of the titanium surface is often characterized by a subtle metallic luster due to an oxide film having a high refractive index present on the surface. Therefore, if any substance having optical characteristics different from those of the refractive index and the like is present in the surface layer, the color tone, gloss and the like are invariably changed, and the substance can be visually recognized depending on the degree of the change. A typical example thereof is an attached fingerprint as the subject of this time. Once the fingerprint is attached to the titanium surface, it is remarkable. The once-attached fingerprint solidifies with time and is difficult to erase even by wiping. In the present invention, the transparent resin in the coating film formed on the titanium surface is closer to the residue of the fingerprint as compared with the titanium oxide film in terms of optical characteristics, and therefore, the fingerprint is not conspicuous even if it adheres. Further, since the transparent resin itself has fluidity, the attached fingerprints can be easily erased by wiping. Further, since the coating layer is a very thin film, even if the optical properties of the resin coating film are different from those of the titanium oxide film, the difference cannot be visually recognized as a change in color tone and glossiness of the titanium surface, and the appearance of the titanium metal surface can be surely prevented from being impaired. In titanium having such a titanium oxide film formed on the surface thereof, both appearance and fingerprint resistance can be achieved, and the metal surface layer of the present invention is particularly effective.

The metal surface layer of the present invention can obtain a better result when the metal surface layer on which the thin film layer is formed has a flatness Ra of 4 to 40 μm. Ra (center line average value) is defined in JIS B0601, and a value measured at a threshold value of 2.5mm can be used herein. When the metal surface is formed with irregularities having a flatness Ra of 4 to 40 μm, the surface is suppressed in gloss and exhibits unique appearance, and therefore, the metal surface is used particularly for building materials and the like not coated with titanium or stainless steel. Now, in the metal surface having the irregularities formed thereon, even if the attached fingerprints are wiped off, since the grease constituting the fingerprints is embedded in the recessed portions of the surface, it is impossible to sufficiently remove the fingerprints. When the metal surface layer of the present invention is applied, since the recessed portions of the metal surface are filled with the resin having fluidity in advance, the adhered fingerprints can be wiped off together with the resin having fluidity, and the fingerprints can be easily removed. In addition, since all the conventionally used surface layers are solid, if the amount of coverage is reduced, the surface cannot be sufficiently covered at the apex of the convex portion of the metal surface. In contrast, the viscosity used in the present invention is 10¹²Pa · s or less has an intrinsic liquid property in this viscosity range, and therefore, even in a film with a small covering amount, the resin can cover the apex of the convex portion on the metal surface. In addition, if the surface roughness is increased, the uneven coating portion of the surface layer becomes less noticeable.

The metal product having the metal surface layer of the present invention has excellent fingerprint resistance while exhibiting the appearance characteristic of metal on the surface thereof, and therefore, is useful for various applications such as interior and exterior decorative sheets for building materials, cameras for appliances, exterior parts for OA equipment, and the like. In addition, the surface layer can be made to have excellent weathering resistance.

Next, a method for forming a metal surface layer according to the present invention will be described.

The transparent resin and wax constituting the metal surface coating film are first dissolved in an organic solvent or water to prepare a transparent resin-containing liquid. As the organic solvent, known organic solvents such as isopropyl alcohol, isopropyl benzene, ethanol, toluene, solvent naphtha, and kerosene can be used. The transparent resin used in the present invention is sticky when used as a coating layerThe degree of the reaction is 10 to 10¹²Pa · s, but the viscosity of a liquid in which the transparent resin is dissolved in the solvent or the like is naturally lower than that. Next, a liquid containing the transparent resin is applied to the metal surface. The method of coating is not limited, and known methods such as spraying, electrostatic coating, roll coating, brush coating, a method of coating after penetrating into a cloth, curtain coating, roll coating, and the like can be applied.

In the present invention, after the liquid is applied to the metal surface, the liquid adhering to the surface is wiped off to form a uniform thin film on the metal surface. In the case of a general paint coating material or a transparent film material, since the solvent is evaporated and solidified after adhering to the metal surface, when the thin film as in the present invention is wiped, the uniform thin film cannot be formed by non-uniform solidification. In the present invention, since the coating film has fluidity even after the solvent is evaporated, a uniform film can be simply formed only by wiping, and the amount of the coating film can be 1.0g/cm²Or a film of the following. When the cover film is wiped with a material that does not damage the metal surface, for example, cloth-made cloth, plastic net, elastic plastic squeegee, paper, or the like, the cover film preferably enters fine irregularities on the metal surface. In particular, when the coating surface has a complicated shape other than a flat surface, it is important to uniformly spread the coating film over the surface by the wiping step. When the coating is uniformly applied, the film layer of the present invention can be formed without wiping when a relatively uniform trace amount of coating is possible by roll coating.

Further, depending on the type of the resin liquid to be applied, the operation of wiping the applied coating film may be performed simultaneously with, after, or before the heat drying. When the resin is a thermoplastic resin, the fluidity of the resin is improved by an increase in temperature, and wiping can be easily performed.

When the covering film layer contains a wax component, the lubricity with a cloth or the like at the time of wiping is improved, and a more uniform thin covering film can be formed.

By performing the above process, a metal product having the cover thin film layer of the present invention can be manufactured.

Detailed Description

Example 1

The metal surface coating of the invention was applied to the surface of a 4-color titanium plate, compared to the existing titanium plate without any coating. The colored titanium plate is formed by an anodic oxidation method, and the color of the colored titanium plate is 4 kinds of green, pink, purple and gold. Further, the use of the colored titanium plate as a test sample is because the appearance is regarded as important and the coating film on the surface is most sensitive to the change in color tone.

The resin-containing liquid for coating the surface of the titanium plate with the metal surface coating has a viscosity of 2.0X 10 as a transparent resin²Pa · s silicone resin: 20 parts, carnauba as wax: 3 parts of isopropanol as solvent: 30 parts and isoparaffins: 47 parts of components. The liquid was allowed to penetrate into the cloth and then applied to a 4-color titanium plate, and was removed by wiping. After sufficiently dried, the amount of deposit was found to be 0.12g/m by gravimetric method²。

The evaluation of fingerprint resistance was carried out by evaluating the recognizability and the wiping property.

The fingerprint identification was evaluated based on whether the fingerprint attached immediately after the fingerprint was attached to the fingerprint after 4 weeks was identifiable. The evaluation was ∘: no recognition, Δ: can identify: is very obvious.

The fingerprint wipeability was evaluated based on how easily a fingerprint was wiped when the fingerprint-adhering portion was wiped with 100% cotton gloves immediately after the fingerprint was adhered, after 1 week, after 4 weeks, and after 1 week after the washing with a weak alkaline detergent. The evaluation was ∘: easy wipe,. Δ: but a little residue on the finger mark, Δ: fingerprint residue, x: it is difficult to wipe.

The metallic surface coating material of the present invention was examined for the effect of weather resistance on fingerprint resistance. Namely, under the UV irradiation conditions: after UV irradiation at 20W for 20cm for 168 hours for 1 week, and after UV irradiation for 1 week and washing with a weak alkaline detergent, fingerprints were adhered, and the ease of fingerprint wiping was evaluated. The evaluation results are shown in table 1.

First, it was confirmed that the titanium plate having a metal surface coating layer according to the present invention had a lower tendency to show a significant decrease in fingerprint, as compared with the titanium plate having no coating layer. Several differences arise in the degree of improvement depending on the color of the colored titanium plate.

The ease of wiping with an attached fingerprint can be greatly improved. As described above, since the fingerprint contains grease secreted from the finger and solidifies with time, it becomes more difficult to remove the fingerprint from the titanium plate not covered with the fingerprint. On the other hand, the titanium plate having the metal surface coating layer of the present invention can maintain almost the same good wiping property even after 1 week or even after 4 weeks, although the color is slightly different.

The weathering resistance of the metal surface coating was confirmed to be sufficient because the scratch resistance of the coating was not changed even with respect to the adhered fingerprint after irradiation in the accelerated test of UV irradiation for 1 week. In addition, no visible chalking or whitish film coating abnormality was observed after UV irradiation.

TABLE 1

With metallic surface coating	Fingerprint identifiability	Immediately after fingerprint attachment for 4 weeks	△(×)	(○)△	(○)△	○△
	Fingerprint identifiability	Immediately after fingerprint attachment for 4 weeks	△(×)	(○)△	(○)△	○△	Wiping property of fingerprint	After the fingerprint is attached	○	○	○	○
	After 1 week	○	○△	△×	○			After the fingerprint is attached	○	○	○	○
	After 1 week	○	○△	△×	○	After 4 weeks		△	○△	△	○(△)
	After 1 week, washing with weak base lotion	○	○	○	○	After 4 weeks		△	○△	△	○(△)
	After 1 week, washing with weak base lotion	○	○	○	○	Fingerprint attachment after 1 week of UV irradiation		○	○	○	○
	Fingerprint attachment after UV irradiation for 1 week + washing	○	○	○	○	Fingerprint attachment after 1 week of UV irradiation		○	○	○	○

Next, the appearance properties of the metal surface coating layer of the present invention were evaluated.

For the 4-color titanium plate, a plate to which the metal surface coating of the present invention was applied and a plate to which neither coating was applied were prepared, and the gloss of both plates and the color difference therebetween were evaluated. Gloss evaluation was measured according to a GS60 meter. Color difference Δ E by CIEL^*a^*b color system (JIS Z8729). The results are shown in Table 2. In the table, L is a measurement result of irradiating light from a vertical direction with respect to the plate flow direction when manufacturing the metal plate, and C is a measurement result of irradiating light from a horizontal direction with respect to the plate flow direction.

When the change in gloss (delta gloss) caused by the application of the coating was observed, the delta gloss by the formation of the cover film was changed between +3 and-15, which was due to the difference in color and the surface properties of the original plate. However, the difference between the uncoated material and the coated material is not visually significant in consideration of the L, C direction difference, the individual difference, and the like in the original edition stage.

If L, C for violet and L for the peak, which are considered outliers, are removed, the color difference is substantially at Δ E, which is difficult to discern to the naked eye: 3 or less, it can be said that there is little change in color tone due to the formation of the coating layer.

TABLE 2

Example 2

The surface of the 4-color titanium plate identical to example 1 was coated with the metal surface coating of the present invention. The resin-containing liquid applied to the surface of the titanium plate for coating the metal surface is prepared from a transparent resin having a viscosity of 8.0X 10³Pa · s water-soluble polyethylene resin: 20 parts of fluorine wax: 5 parts, water as solvent, isopropyl alcohol: 75 parts of components. The coating method and the like are the same as in example 1. The amount of deposit was found to be 0.28g/m by gravimetric method²。

The identifiability and the wiping property for the evaluation of the fingerprint resistance were carried out in the same manner as in example 1, and the results are shown in table 3. As compared with the case where no metal surface coating was applied (table 1), the results of good fingerprint identifiability and wiping property were clearly obtained.

TABLE 3

With respect to the appearance property produced by the metal surface coating layer of the present invention, evaluation was made in the same manner as in example 1. The results of Δ gloss and Δ E are shown in table 4, compared to the case where no metal surface coating was performed (table 2). The same and good appearance as in example 1 was achieved.

TABLE 4

As described above, the present invention has 10 to 10 parts by forming on the surface of the metal¹²A coating film layer mainly composed of a transparent resin having a viscosity of Pa · s can provide a metal surface coating layer which maintains good appearance and fingerprint resistance of the metal surface.

In addition, the weathering resistance of the coating thin film layer can be improved by adding at least one resin containing one or more atoms of Si, B, Ti, F, Ge, and Se, an organic compound, and an organic-inorganic composite to the resin.

Furthermore, the invention coats the metal surface with a coating containing 10-10 wt.% of a metal¹²The metal surface coating layer can be easily formed by wiping the applied liquid with a liquid of a transparent resin having a viscosity of Pa · s.

Claims

1. A metal surface coating is characterized in that the coating is formed on the metal surface to have a thickness of 10-10%⁶A covering film layer mainly composed of a thermoplastic resin having a viscosity of Pa · s.

2. The metal surface coating according to claim 1, wherein the amount of the coating film layer is 0.01 to 1.0g/m²。

3. The metal surface coating according to claim 1, wherein the resin contains at least one of a resin, an organic compound, and an organic-inorganic composite containing one or more atoms selected from Si, B, Ti, F, Ge, and Se.

4. The metal surface coating according to claim 1, wherein the covering film layer contains a wax component.

5. The metal surface coating according to claim 1, wherein a layer containing titanium, a titanium alloy or a titanium-containing compound as a main component is formed on the metal surface, and the thin coating film layer is formed thereon.

6. The metal surface coating according to claim 1, wherein the metal surface has a flatness Ra of 4 to 40 μm.

7. A metal product having the metal surface coating according to any one of claims 1 to 6.

8. The method for forming a metal surface coating according to any one of claims 1 to 6, wherein the metal surface is coated with a coating composition containing 10 to 10% by weight of a metal oxide⁶A liquid of a thermoplastic resin of Pa · s viscosity, and then wiping the applied liquid.

9. The method of treating a metal product according to claim 7, wherein the metal surface is coated with a coating composition containing 10 to 10 wt.% of a metal⁶A liquid of a thermoplastic resin of Pa · s viscosity, and then wiping the applied liquid.