KR20120075362A - Coating solution for forming transparent film and substrate coated by transparent film - Google Patents

Abstract

PURPOSE: A coating solution for forming a transparent film is provided to have excellent adhesion with a substrate, scratch resistance, film strength, transparence, etc, and to have excellent chemical resistance, and water repellency at the same time, and to able to form a transparent film with excellent haze because of not blooming phenomenon. CONSTITUTION: A coating solution for forming a transparent film consists of a matrix-forming component, metal oxide particle, and solvent, and comprises acryl silicone resin with average molecular weight range of 5,000-30,000 as a leveling agent. The content of leveling agent is 0.001-7.2 weight% in solid phase. The content of the matrix-forming component is 1-59.9 weight% in solid phase. The content of the metal oxide particle is 0.025-48 weight% in solid phase. The total content of solid phase is 5-60 weight%.

Description

Coating solution for forming transparent film and substrate {Coating solution for forming transparent film and substrate coated by transparent film}

The present invention relates to a coating liquid for forming a transparent coating having high flatness and excellent in whitening resistance, water resistance, chemical resistance, and the like, and the transparent coating part base material.

Background Art It is known to form a transparent coating having a hard coating function on the surface of a substrate in order to improve scratch resistance of a surface of a substrate such as glass, a plastic sheet, a plastic lens, or a display device. Specifically, forming an organic resin film or an inorganic film having transparency on the surfaces of glass and plastic display substrates and the like is performed. At this time, by mixing inorganic particles such as resin particles or silica in the organic resin film or the inorganic film, improving adhesion to the substrate and scratch resistance are performed.

However, in addition to adhesion to a transparent substrate, film strength, scratch resistance, and the like, a transparent coating is required for chemical resistance, water resistance, water repellency, anti-fingerprint adhesion, and the like. For example, if water droplets are attached, do not retain the water droplets (water resistance), do not allow graffiti with water-based pens, oil pens, etc. to be easily erased (water-resistant, water-repellent, oil-repellent), or finger touch Even if the fingerprint is attached, it is desired to be able to easily erase it even if the fingerprint is attached (fingerprint resistance).

In order to impart such water repellency, oil repellency, water resistance and anti-fingerprint property, a silicone resin having a hydrophilic group, a fluorine-containing organic resin, or the like has been used as a leveling agent (Patent Document 1; Japanese Patent Laid-Open No. 10-40834, etc.).

On the other hand, the present applicant discloses using a monofunctional silicone resin monomer in combination with other polyfunctional silicone resins and obtaining a transparent film excellent in water repellency without the above bleed out (Patent Document 2; Japanese Patent Application Laid-Open No. 2010-126675). report).

Japanese Patent Application Laid-Open No. 10-40834 Patent Document 2 Publication No. 2010-126675

Therefore, in the conventional method, even if the water repellency, oil repellency, and fingerprint adhesion are improved to some extent, the adhesion to the substrate and the film strength may be insufficient, and the water repellency may be insufficient.

In addition, even when a mixture of a hydrophobic group, such as a fluorine resin, is used, the resin is separated from the transparent film, i.e., bridout, and sufficient chemical resistance, water resistance, water repellency, oil repellency, and fingerprint adhesion cannot be obtained. In many cases, even when obtained, there was a problem of performance deterioration over time.

In the case of forming a transparent coating on the TAC substrate, the surface of the TAC substrate in which the transparent coating substrate is deposited in a saponification bath is saponified in order to adhere to the adhesive article. There were problems such as dissolution of the transparent film, whitening of the transparent film, deterioration of the haze, deterioration of the contact angle of the transparent film, and deterioration of scratch resistance.

On the other hand, even when vinyl resin, acrylic resin, or the said fluorine resin is used as a leveling agent, there existed a problem in compatibility with another matrix formation component, and the hardness of the obtained transparent film may become inadequate.

Further, in Patent Document 2, even if the transparency haze is improved, the suppression of whitening is insufficient, and the flatness of the surface of the transparent coating is not satisfied as necessary.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining such a problem, when the modified silicone type resin matrix formation component which adjusted the molecular weight to the appropriate range was mixed and used as a leveling agent, this inventor discovered that the transparent film which suitably solved the said subject was obtained, It is complete.

In other words, the present invention has excellent adhesion to the substrate, scratch resistance, film strength, transparency, etc., and also has excellent chemical resistance, water repellency, and no whitening. It is an object to provide a subsidiary.

[1] A coating liquid for forming a transparent film comprising a matrix forming component, metal oxide fine particles and a solvent,

The coating liquid for transparent film formation containing acrylic silicone resin whose average molecular weight is a range of 5,000-30,000 as a leveling agent, and content of a leveling agent is 0.001 to 7.2 weight% as solid content.

[2] The transparency of [1], wherein the concentration of the matrix forming component is in the range of 1 to 59.9 wt% as solids and the total solid concentration is 5 to 60 wt% in the range of 0.025 to 48 wt% as the content of the metal oxide fine particles. Coating liquid for film formation

[3] at least one or more selected from the above metal oxides and composite oxides thereof, wherein the metal oxide fine particles include silica, alumina, titanium oxide, zirconium oxide, tin oxide, titanium pentoxide, indium oxide and complex oxides thereof, and a dopant. Coating liquid for transparent film formation of [1] or [2] which is microparticles | fine-particles

[4] The coating liquid for forming a transparent film of [3], wherein the metal oxide fine particles are silica-based fine particles.

[5] The coating solution for forming a transparent film of [1] to [4], wherein the metal oxide fine particles are surface treated with an organosilicon compound.

[6] The coating liquid for forming a transparent film of [1] to [5], wherein the metal oxide fine particles have an average particle size in the range of 5 to 300 nm.

[7] A base film and a transparent film formed on the base material, wherein the transparent film is composed of a matrix component and metal oxide fine particles, and contains an acrylic silicone resin having an average molecular weight in the range of 5,000 to 30,000 as a leveling agent, and the content of the matrix component. As a solid content, it is the range of 20-99.9 weight%, and content of the said metal oxide fine particle is 0.5 to 80 weight% range as solid content

[8] The transparent coating part base material of [7], wherein the leveling agent content in the transparent coating is in the range of 0.02 to 12 wt% as solid content.

[9] The metal oxide fine particles are at least one or more fine particles selected from silica, alumina, titania, zirconia, tin oxide, titanium pentoxide, indium oxide and complex oxides thereof, oxides including dopants, and complex oxides [7] Or the transparent coating part base material of [8]

[10] The transparent coating part substrate according to [7] to [9], wherein the metal oxide fine particles are silica-based fine particles.

[11] The transparent coating part substrate of [7] to [10], wherein the metal oxide fine particles are surface treated with an organosilicon compound.

[12] The transparent coating part substrate of [7] to [11], wherein the average particle size of the metal oxide fine particles is in the range of 5 to 300 nm.

[13] The contact angle (CA ₁ ) of the transparent film is in the range of 60 to 110 ° and the surface of the transparent film is saponified, and then the difference between the contact angle (CA ₂ ) and the contact angle is 10 ° or less. 12] transparent coating part base material

[14] The transparent coating part substrate of [7] to [13], wherein the haze of the transparent coating is 1.0% or less.

[15] The transparent coating part substrate of [7] to [14], wherein the surface roughness Ra of the transparent coating is 20 nm or less.

According to the present invention, a small amount of the acrylic silicone resin matrix component having a molecular weight in a predetermined range is added to the matrix forming component, thereby providing excellent adhesion to the substrate, scratch resistance, film strength, transparency, etc., and excellent chemical resistance, water resistance, and surface. It is possible to provide a coating film for forming a transparent film and a transparent coating part base material for forming a transparent film having a high haze that is flat, smooth and not whitened.

Hereinafter, the coating liquid for transparent film formation which concerns on this invention is demonstrated in detail.

[Coating Liquid for Transparent Film Formation]

The coating liquid for transparent film formation by this invention consists of a leveling agent, a matrix formation component, metal oxide fine particles, and a solvent.

Leveling agent

Acrylic silicone resin is used as a leveling agent. In addition, as a leveling agent, it has a function of imparting adhesion, scratch resistance, film strength, transparency, chemical resistance, water resistance, water repellency, anti-fingerprint property, and flat smoothness to a transparent film.

As the acrylic silicone, a polymer of a bifunctional silicone resin represented by the following formula (1) and a silicone polymer which is a polymer of a monofunctional silicone resin represented by the following formula (2) are used as the main chain, and the side chain is placed at the terminal via a polyester group. And acrylic silicone resins (A) having two acrylic groups or methacryl groups bonded thereto.

(Formula 1, 2)

Wherein R ₁ to R ₄ represent a hydroxyl group, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, oxyalkyl group, polyether group (-OR), polyoxyalkyl group ((-(OR) n), alkyloxycarbonyl group, poly Ester group, polyalkyloxycarbonyl group, urethane group (-CONH-R), polyurethane group ((-CONH-R) n-CONH-R), aralkyl group,

Ｙ, Ｙ ₁ , Ｙ ₂ are -O-CO-R "-, -CO-OR",-(O-CO-R ") n-,-(CO-OR") n- (where R "is 2 And a hydrocarbon group or a direct bond), and a polyester group, and X, X ₁ , X ₂ represent an acryl group and a methacryl group, and may be the same or different.

n is an integer of 1-50.

Specifically, diacrylate modified polysiloxane, dimethacrylate modified polysiloxane, and mixtures thereof are mentioned.

Moreover, in this invention, the acrylic polymer represented by following formula (3) can be used as the main chain, and the acrylic silicone resin (B) by which silicone was couple | bonded with the side chain.

(Formula 3)

Wherein R ₁ or R ₂ is hydrogen or CH ₃ , R ₃ is an alkyl group, a polyester group, a polyether group, a polyurethane group, an aralkyl group or a salt, and R ₄ is Si—OR ′, — (Si-O nR '(R is an alkyl group or a hydroxyl group) and is two or more polymers.

In the present invention, the weight average molecular weight of such acrylic silicon is 5,000 to 30,000, preferably 6,000 to 20,000. The thing of such a molecular weight is excellent in a function as a leveling agent.

In addition, when the molecular weight is too low, it is unevenly distributed in the paint and does not melt together, so that it dissolves and detaches in the saponification process after forming the film, so that it is easy to whiten and the contact angle does not decrease, so that sufficient water repellency and water resistance may not be exhibited. Even if the average molecular weight is too high, it may not function as the leveling agent because it does not substantially melt together in the paint. The average molecular weight of such a matrix forming component can be measured by the polystyrene conversion molecular weight measured by the gel permeation (GPC) method using a tetrahydrofuran (THF) solvent.

Matrix forming components

In the present invention, an organic resin matrix forming component is used as the matrix forming component. Specifically, conventionally known paint resins may be enumerated, and specifically, polyester resins, polycarbonate resins, polyamide resins, polyphenylene oxide resins, thermoplastic acrylic resins, vinyl chloride resins, fluorine resins, vinyl acetate resins, and silicones. Thermoplastic resins such as rubber, urethane resins, melamine resins, silicon resins, butyral resins, phenol resins, epoxy resins, unsaturated polyester resins, thermosetting acrylic resins, and ultraviolet curing acrylic resins.

Specific examples of the organic resin matrix components include pentaerythritol triacrylate, trimethylloylpropane tri (meth) acrylate, pentaerythritol tetraacrylate, ditrimethyloyl propane tetra (meth) acrylate, and dipentaerythritol hexaacrylate. , Diethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2 -Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-acryloyloxypropyl acryl Rate, methoxy triethylene glycol dimethacrylate, butoxydiethylene glycol methacrylate, tri Ethylene glycol diacrylate, 1,6-hexanediol diacrylate, 2-methacryloxyethyl succinic acid, 2-acrylooxyethyl succinate, 2-acrylooxymethyl succinic acid, 2-methacryloxyethyl hexahydro Phthalic acid, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, 2-methacryloyloxyethylacetophosphate, 2-methacryloyloxyethylacetophosphate, 2-acryloyloxyethylacetophosphate and mixtures thereof or in the hydrophilic organic resin matrix-forming component or a vinyl group of the resin of two or more copolymers and modification products, such as, a urethane group, an epoxy group, (meth) acrylic multi having a hydrophobic functional group, such as weather, CF ₂ group-functional (meth) acrylic acid Ester resin is mentioned.

Specifically, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol hexaacrylate, methyl Methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl acrylate, n-stearyl acrylate, 1, 6-hexanediol dimethacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, urethane acrylate, etc. can use hydrophobic organic resin matrix formation components, such as a mixture thereof.

In the present invention, an ultraviolet curable resin or an electron beam curable resin is also preferable. It is preferable to use ultraviolet curable resin especially for this invention.

Specific examples of the six-functional UV-curable resin include dipentaerythritol hexaacrylate. Examples of the four-functional UV-curable resin include pentaerythritol tetraacrylate. As methacrylate, trimethylloyl propane triacrylate, isocyanuric acid triacrylate, pentaerythritol hexamethylene diisocyanate urethane prepolymer, bifunctional ultraviolet curing resin, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate , Polypropylene glycol dimethacrylate, 1,4-pentanediol dimethacrylate, 1,4-hexanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate Acrylate, 1,10-decanedioldimethacrylate, glycerindimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 2-methacryloyloxyethyl acetate phosphate, 2-acryloyloxyethyl acetate Phosphate, polyflophylene glycol diacrylate, tripropylene glycol diacrylate, tetraethylene acrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 3-methyl-1,5-pentanediol diacrylate, 3-methyl-1,7-octanedioldiacrylate, 1,6-hexanedioldiacrylate, 2-butyl-2-ethyl-1,3-propanedioldiacrylate, 1,9-nonanedioldiacrylate Rate, 1,10-decanedioldiacrylate, 2,4-diethyl-1,5-hexanedioldiacrylate, dimethylloyltricyclodecanediacrylate, 2-hydroxy-3-acryloyloxy Propyl methacrylate, bisphenol A diacrylate , Perfluoro butyl ethyl methacrylate location, there may be mentioned ethyl methacrylate, and mixtures thereof trifluoromethyl.

As the organic resin matrix forming component, a monomer may be used, but an oligomer or a polymer of two or more dimers may be used.

When such an ultraviolet curable resin is used, a transparent coating excellent in scratch resistance, hardness, and the like can be produced in a short time treatment.

Metal oxide fine particles

As metal fine particle oxide fine particles used for this invention, the conventionally well-known metal oxide fine particle normally used for a transparent film can be used. In this invention, it is preferable that it is at least 1 sort (s) chosen from silica, alumina, titania, zirconia, tin oxide, antimony pentoxide, indium oxide and its complex oxide, oxide containing a dopant, and complex oxide.

These particles can be appropriately selected and used in consideration of the refractive index, transparency, antistatic performance and the like of the transparent coating.

In the present invention, the metal oxide fine particles are preferably silica particles.

The silica-based fine particles may include particles other than silica, alumina, titania, or the like within the range of meaning particles containing silica as a main component and not impairing transparency. Furthermore, in the present invention, monodisperse spherical silica fine particles are preferred. By using such particles, a transparent coating excellent in scratch resistance, transparency, haze, and the like can be obtained.

The metal oxide fine particles are preferably surface treated with an organosilicon compound (also referred to as a silane coupling agent), and the surface treatment method is not particularly limited and conventionally known methods can be employed, for example, an alcohol dispersion liquid of metal oxide fine particles. The surface treatment can be carried out by adding an organosilicon compound to the mixture and, if necessary, hydrolysis by adding a catalyst for hydrolysis of an organosilicon compound such as an acid or an alkali.

The surface-treated metal oxide fine particles can be highly dispersed in an organic solvent and an organic resin matrix forming component to obtain a stable coating liquid, and the resulting transparent coating is excellent in scratch resistance, transparency, haze, and the like.

The average particle diameter of the metal oxide fine particles is preferably in the range of 5 to 300 nm, more preferably 8 to 200 nm.

If the average particle diameter of the metal oxide fine particles is too small, the particles tend to aggregate easily, and it is difficult to high disperse the aggregated particles, and the haze of the obtained transparent film may deteriorate. Even if the average particle diameter of metal oxide microparticles | fine-particles is too big, transparency of a transparent film may fall, and haze may worsen.

Polymerization initiator

The coating liquid of this invention may contain the polymerization initiator according to the matrix formation component to be used. As a polymerization initiator, a well-known thing can be used without a restriction | limiting in particular, For example, bis (2, 4, 6- trimethyl benzoyl) phenyl phosphine oxide, bis (2, 6- dimethoxy benzoyl) 2, 4, 4- Trimethylpentylphosphine oxide, 2-hydroxy-methyl-2-methyl-phenyl-propane-1-ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclo Hexyl-phenyl-ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, and the like. Moreover, if necessary, well-known components, such as a sensitizer and a hardening adjuvant, may be contained.

menstruum

As a solvent used for this invention, the conventionally well-known solvent which can melt | dissolve or disperse the said matrix formation component and the polymerization initiator used as needed, and can disperse | distribute the said metal oxide fine particle uniformly can be used.

Specifically water; Alcohols such as methanol, ethanol, propanol, 2-propanol (IPA), butanol, diacetone alcohol, furfurylalcohol and tetrahydrofurfuryl alcohol; Methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, isopentyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2-ethylbutyl acetate, cyclohexyl acetate, ethylene glycol monoacetate, etc. Glycols such as esters, ethylene glycol and hexylene glycol; Diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol isopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol Hydrophilic solvent containing ethers such as monoethyl ether, propyl acetate, isobutyl acetate, butyl acetate, isopentyl acetate, pentyl acetate, 3-methoxybutyl acetate, 2-ethylbutyl acetate, cyclohexyl acetate, ethylene glycol mono Esters such as acetates; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, butyl methyl ketone, cyclohexanone, methylcyclohexanone, dipropyl ketone, methyl pentyl ketone and diisobutyl ketone; And polar solvents such as toluene. These may be used independently, or may mix and use 2 or more types.

Composition of Coating Liquid for Transparent Film Formation

It is preferable that the density | concentration of the matrix formation component containing the leveling agent in the coating liquid for transparent film formation is 1 to 59.9 weight%, Furthermore, it is the range of 2 to 59.4 weight% as solid content. When there are few matrix forming components in the coating liquid for transparent film formation, the matrix component in the transparent film obtained will become small, content of metal oxide fine particles may become large too much, and scratch resistance may become inadequate. Moreover, the transparent film of a thick film may not be able to be formed by one application | coating, and there exists a problem that productivity is reduced by requiring application | coating and drying repeatedly.

Even if there are too many matrix forming components in the coating liquid for transparent film formation, content of the metal oxide fine particle in the transparent film obtained may become small, and adhesiveness with a base material, sufficient scratch resistance, strength, etc. may not be obtained.

It is preferable that the density | concentration of the acrylic silicone as a leveling agent in the coating liquid for transparent film formation exists in the range of 0.001 to 7.2 weight%, Furthermore, 0.002 to 6 weight% as solid content.

When the concentration of the leveling agent is small, in the drying step after coating, the surface tension of the coating film surface cannot be kept low (surface tension is high), the surface smoothness is poor, and appearance defects such as orange peel may occur. Moreover, the contact angle of a transparent film also becomes small, and water resistance and water repellency may become inadequate. Even if there are too many leveling agents, the hardness and strength of a transparent film may become inadequate.

The concentration of the metal oxide fine particles in the coating liquid for forming a transparent film is preferably in the range of 0.025 to 48% by weight, and more preferably 0.1 to 40% by weight as solid content.

When there are few metal oxide microparticles | fine-particles, content of the metal oxide microparticles | fine-particles in the transparent film obtained may become small, and adhesiveness with a base material, abrasion resistance, film hardness, film strength, etc. may become inadequate. Even if there are too many metal oxide fine particles, content of the matrix component in the transparent film obtained will become small, and adhesiveness with a base material and scratch resistance will become inadequate.

It is preferable that the total solid content concentration of the coating liquid for transparent film formation exists in the range of 5-60 weight%, Furthermore, it is 10-50 weight%. If the total solid content is small, it may be difficult to obtain a transparent film having a thickness of 0.5 μm or more in one coating. If repeated application and drying are repeated, the hardness and the scratch resistance of the transparent film obtained are insufficient, or the haze or The appearance may deteriorate and productivity may become a problem. Even if the total solid content is too high, the viscosity of the coating liquid may be high, so that the applicability is lowered, the haze of the obtained transparent film is increased, or the surface roughness is large, resulting in insufficient scratch resistance.

The method of forming a transparent film using the coating liquid for forming a transparent film is applied to a substrate by a known method such as dipping method, spray method, spinner method, roller coat method, gravure printing method, microgravure printing method, and then dried. Next, a transparent film can be formed by hardening by a conventional method, such as ultraviolet irradiation and heat processing.

The film thickness of the transparent film of the obtained transparent film part base material exists in the range of 0.5-20 micrometers, and it is excellent in adhesiveness with a base material, abrasion resistance, film hardness, film strength, transparency, haze, etc., and the surface is flat and saponification process is carried out. Even if it is not whitening, water resistance, chemical resistance and the like is excellent.

Next, the transparent coating part base material which concerns on this invention is demonstrated.

[Transparent coating part description]

The transparent coating part base material which concerns on this invention is a transparent film formed on the base material and the base material, or the said transparent film consists of a matrix component and metal oxide fine particles.

materials

As a base material used for this invention, a well-known thing can be used without a restriction | limiting in particular, Plastic sheets, such as glass, polycarbonate, acrylic resin, PET, and TAC, plastic panels, such as a plastic film, etc. are mentioned. In particular, substrates such as polycarbonate, acrylic, PET, and TAC, in particular, TAC substrates can suppress interference fringes because some of the substrates are dissolved or swelled so that the transparent coating components enter each other and the interface at the boundary becomes unclear. It can use suitably.

Transparent film

The transparent coating contains a matrix component and metal oxide fine particles or a matrix component and a leveling agent.

Matrix components

The matrix component is a cured product of the matrix forming component described above. It is preferable that content of the matrix component in a transparent film exists in the range of 20-99.9 weight%, Furthermore, 40-99 weight%. When there are few matrix components, content of the matrix component in the transparent film obtained may become small and scratch resistance may become inadequate. Even if there are too many matrix components, content of the metal oxide fine particle in the obtained transparent film may become small and scratch resistance may become inadequate.

Leveling agent

It is preferable that a leveling agent turns into hardened | cured material in a film, and the content exists in the range of 0.02-12 weight%, Furthermore, 0.04-10 weight% as solid content. When there are few leveling agents, in the process after application | coating as mentioned above, surface tension of a coating film surface may not be kept low (surface tension becomes high), surface smoothness may be bad, and appearance defects, such as an orange peel, may arise. Moreover, the contact angle of a transparent film also becomes low and water resistance may become inadequate. Even if there are too many leveling agents, the hardness or strength of a transparent film may become inadequate.

In addition, the cured product of acrylic silicone used as a leveling agent in the transparent coating is relatively ubiquitous on the upper surface of the transparent coating, and when the ratio of the cured acrylic silicone polymer polymer in the matrix component is high, it is present in the fine state in the transparent coating to make the transparent coating. May have insufficient hardness or strength.

When the leveling agent is ubiquitous, the surface tension of the surface of the coating film can be lowered, so that the surface smoothness is good, the appearance unevenness is reduced, and the contact angle is high, thereby obtaining a transparent film having excellent water resistance.

In addition, when the leveling agent is ubiquitous, since it has affinity with the substrate, it acts as a humectant, so that even if a foreign substance is present on the substrate, it is possible to cover it and to obtain a transparent film free from defects caused by the foreign substance.

Metal oxide fine particles

As metal oxide fine particles used for the transparent film of this invention, said metal oxide fine particles are used.

It is preferable that content of the metal oxide microparticles | fine-particles in a transparent film exists in the range of 0.5 to 80 weight%, Furthermore, 1 to 60 weight% as solid content. When there are few metal oxide fine particles, since there is little content of metal oxide fine particles in a transparent film, when the remarkable effect of using metal oxide fine particles is not acquired, for example, adhesiveness with the base material of a transparent film, transparency strength, etc. may become inadequate. .

Even if there are too many metal oxide fine particles, the haze and transparency of a transparent film may worsen, and since there are few matrix components, adhesiveness with a base material, abrasion resistance, and film strength may become inadequate.

Usually, it is preferable that the film thickness of a transparent film exists in the range of 0.5-30 micrometers, Furthermore, 1-20 micrometers. When the film thickness of the transparent film is thin, scratch resistance may be insufficient, and even if too thick, curling may occur due to shrinkage of the film or adhesion with the substrate may be insufficient.

Since the transparent film formed by this invention becomes said component, the surface is flat and surface roughness Ra becomes 20 nm or less. Especially as a transparent film, it is preferable that Ra is 15 nm or less. When surface roughness Ra exists in this range, since the surface smoothness of a coating film is high and a contact angle is large, it is excellent in water resistance and water repellency. In addition, scratch resistance and film hardness are high. Such surface roughness Ra can be measured by a laser microscope.

In addition, the contact angle (CA ₁ ) of the transparent film formed in the present invention is in the range of 60 ~ 110 °. As a transparent film, it is preferable to exist in the range of 70-100 degree. When the contact angle CA ₁ of the transparent film is within this range, the water resistance is high, and if necessary, when the other transparent film, for example, an antireflection film is laminated on the transparent film of the present invention, adhesion to each other can be maintained, and scratch resistance, The film strength does not decrease. Moreover, when a contact angle is out of the said range, a transparent film may whiten, a haze may deteriorate, and abrasion resistance may worsen.

In addition, the transparent coating film of the invention has a contact angle difference of the contact angle (CA ₂₎ after the saponification treatment for the transparent film wherein the contact angle (CA ₁₎ is not more than 10 °. In particular, this difference is more effective than 8 ° or less. In addition, when the contact angle difference is large and the refractive index difference is small before and after the saponification treatment, the whitening of the transparent film proceeds, and transparency, haze and the like may be insufficient.

The contact angle can be measured by a fully automatic contact angle meter (manufactured by Cooperative Interface Science Co., Ltd .: DM 700).

Moreover, the haze of a transparent film exists in 1.0% or less, and it is especially preferable that it is 0.8% or less.

When the haze of a transparent film exists in this range, transparency is set and when it is used as an optical thin film, for example, for display screens, such as a liquid crystal display device, display performance, such as contrast, brightness, and precision, becomes excellent.

To adjust the surface roughness, the use of the acrylic silicone-based leveling agent according to the present invention or the amount thereof is changed. In order to adjust a haze, it adjusts by use of the acrylic silicone type leveling agent used for this invention, or the change of the quantity other than the particle diameter and content of the metal oxide fine particle to be used. To adjust the contact angle: The use of the acrylic silicone leveling agent according to the present invention or the amount of use thereof is adjusted. In order to adjust a contact angle difference, the acrylic silicone type leveling agent in the range of predetermined average molecular weight which is hard to melt | dissolve in alkali is used. In addition, it is not to adjust arbitrarily, but to coordinate with each other.

As described above, in the present invention, acrylic silicone having a predetermined average molecular weight is used as the leveling agent together with the matrix component, so that the adhesion, scratch resistance, film strength, transparency, etc. to the substrate are excellent, and chemical resistance, water resistance, water repellency, and fingerprint It is possible to provide a transparent coating substrate having excellent adhesion, smooth and smooth surface and excellent haze without whitening.

Such a transparent film can be produced by applying and curing the coating solution described above.

[Example]

The present invention will be described in more detail with reference to the following Examples, but the present invention is not limited to these Examples.

[Example 1]

Preparation of the coating liquid 1 for transparent film formation

Silica fine particle dispersion (you kkisyo Cuba divalent assay (Co., Ltd.); OSCAL1432; average particle size 12 nm, SiO ₂ concentration of 30.5% by weight, dispersing medium: isopropanol, refractive index of particles 1.46) γ- meth acryloxy propyl trimethoxy silane and 4.50 to 100g g (Shinwol Silicone Co., Ltd .; KBM-503, 81.2% of SiO ₂ component) were mixed, 3.1 g of ultrapure water was added, and stirred at 50 ° C. for 20 hours to obtain a surface-treated silica fine particle dispersion having a solid content of 30.5 wt% (1) Obtained.

Thereafter, solvent substitution was performed on propylene glycol monopropyl ether (PGME) using a rotary evaporator to obtain silica fine particle PGME dispersion (1) having a solid content concentration of 40.5% by weight.

Subsequently, 51.85 g of silica fine particles PGME dispersion (1) and 18.80 g of dipentaerythritol hexaacrylate (DPE-6A manufactured by Kogyo Chemical Co., Ltd.) at a solid content concentration of 40.5% by weight (1,6-hexanediol diacrylate) Kogyo Chemical Co., Ltd. make: 4.20 g of light acrylate SR-238F, 0.20 g of acrylic-based leveling agent (Nambon Chemical Co., Ltd. make: Disparon NSH-8430HF), and photoinitiator (ciba Japan Co., Ltd. make) : Irgacure 184, dissolved in 10% solids concentration in PGME) 12.60 g, 4.35 g of PGME, and 10.0 g of acetone were sufficiently mixed to prepare a coating solution (1) for forming a transparent film having a solid content of 42.0 wt%. As a result of measuring the molecular weight of the leveling agent, the average molecular weight was 11,000.

Preparation of the transparent coating part base material 1

The coating liquid 1 for transparent film formation was apply | coated to TAC film (made by Panak Co., Ltd .: FT-PB80UL-M, thickness: 80 micrometers, refractive index: 1.51) by the bar coat method (# 14) for 120 second at 80 degreeC. After drying, 300 mJ / cm ² ultraviolet ray was irradiated and cured to prepare a transparent coating part substrate 1. The film thickness of the transparent film was 6 micrometers.

The total light transmittance and the haze of the obtained transparent coating part substrate were measured by a haze meter (manufactured by Suga Tester Co., Ltd.). In addition, the TAC film of the coating liquid had a total light transmittance of 9.32% and a haze of 0.2%.

Moreover, adhesiveness, soap-resistant, abrasion resistance, pencil hardness, and surface roughness are measured and evaluated by the following method, and a result is shown in a table | surface.

Soap resistance evaluation

Saponification test method: The transparent coating part base material 1 is immersed in 40 degreeC 10 wt% NaOH aqueous solution for 80 second. The contact angles CA ₁ and CA _{2 on the} surface of the transparent film before and after the saponification test were measured by a fully automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd .: DM 700) to obtain a contact angle difference, and the results are shown in the table.

Measurement of scratch resistance

Sliding 10 times under a load of 2kg / cm ² using # 0000 steel wool, the surface of the membrane was visually observed, evaluated according to the following criteria, and the results are shown in Table 1.

Evaluation standard:

The wound of each item is not confirmed: ◎

Each item has a slight wound. : ○

Many wounds of each item are confirmed. : △

The surface is entirely carved. : ×

Adhesion

The surface of the transparent coating base material (F-1) is made with 11 parallel wounds and 100 cells at intervals of 1 mm by a knife, and then adheres to the cellophane tape (registered trademark), and then the cellophane tape (registration) When peeling off the trademark), the number of cells remaining without peeling off the coating was classified into the following four steps to evaluate the adhesion. The results are shown in Table 1.

95 or more spaces remaining: ◎

Number of spaces remaining 90 ~ 94: ○

85 to 89 spaces remaining: △

Number of spaces remaining 84 or less: ×

Measurement of pencil hardness

It measured by the pencil hardness tester according to JIS-K-5600.

Measurement of surface roughness

It measured by the laser microscopy.

Example 2

Preparation of the coating liquid 2 for transparent film formation

In Example 1, the coating liquid 2 for transparent film formation of 42.0 weight% of solid content concentration was produced like it except having mixed 0.05g of acrylic silicone leveling agents.

Preparation of the transparent coating part base material 2

In Example 1, the transparent coating part base material 2 was manufactured similarly except having used the coating liquid for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Example 3

Preparation of the coating liquid 2 for transparent film formation

In Example 1, the coating liquid 3 for transparent film formation of 42.0 weight% of solid content concentration was produced like it except having mixed 1.0g of acrylic silicone type leveling agents.

Preparation of the transparent coating part base material 3

In Example 1, the transparent coating part base material 3 was manufactured similarly except having used the coating liquid 3 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

[Example 4]

Preparation of the coating liquid 4 for transparent film formation

In Example 1, the coating liquid 4 for transparent film formation of 42.0 weight% of solid content concentration was carried out similarly except having mixed acrylic silicone crab leveling agent (Nambon Chemical Co., Ltd. make: Disparon SF-8363). Prepared. At this time, the average molecular weight was 7,500 when the molecular weight of the leveling agent was measured.

Preparation of the transparent coating part base material 4

In Example 1, the transparent coating part base material 4 was produced similarly except having used the coating liquid 4 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Example 5

Preparation of the coating liquid 5 for transparent film formation

To 600 g of silica fine particle dispersion (Nikishokubai Kasei Co., Ltd. product: CATALOID SI-50; average particle diameter 25 nm, dispersion number, SiO ₂ concentration 48% by weight), 600 g of pure water was added to make 30% concentration, and cation 336 g of an exchange resin (Mitsubishi Chemical Corporation: Dion SK1B) was ion-exchanged at 80 ° C. for 3 hours to obtain a silica fine particle dispersion 2 having a solid content concentration of 30% by weight.

The silica fine particle dispersion 2 having a solid content concentration of 30% by weight was solvent-substituted with methanol using an ultrafiltration membrane to obtain a silica fine particle dispersion 2 with a solid content concentration of 30% by weight.

Next, 4.50 g of gamma -methacryloxypropyl trimethoxysilane (made by Shinwol Silicon Co., Ltd .: KBM-503, SiO2 component 81.2%) was mixed with 100 g of this silica fine particle methanol dispersion (2), and 3.1 g of ultrapure water was added, and 50 It stirred at 20 degreeC for 20 hours, and obtained the silica fine particle dispersion 2 surface-treated (solid content concentration 30.5 weight%).

Solvent substitution of propylene glycol monomethyl ether (PGM) with a rotary evaporator yielded a silica particulate PGME dispersion (2) having a solid content of 40% by weight.

Next, in Example 1, the coating liquid for transparent film formation of 42.0 weight% of solid content concentration similarly except having used the silica fine particle PGME dispersion (2) instead of the silica particle PGME dispersion liquid (4) of solid content concentration 40.5 weight%. (5) was prepared.

Preparation of the transparent coating part base material 5

In Example 1, the transparent coating part base material 5 was manufactured similarly except having used the coating liquid 5 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Example 6

Preparation of the coating liquid 6 for transparent film formation

333 g of pure water was added to 1000 g of silica fine particle dispersion (Nikishokubai Kasei Co., Ltd. product: CATALOID SI-80P; average particle diameter 80 nm, SiO ₂ concentration 40 weight%, dispersion medium; water), and solid content concentration was 30 weight% Then, 336 g of a cation exchange resin (Diion SK1B manufactured by Mitsubishi Chemical Co., Ltd.) was ion-exchanged at 80 ° C. for 3 hours to obtain silica fine particle dispersion 3 having a solid content concentration of 30% by weight. . This dispersion was solvent-substituted with methanol using an ultrafiltration membrane to obtain a silica particulate methanol dispersion (3) having a solid content concentration of 30% by weight.

100 g of silica fine particle methanol dispersion (3) was mixed with 4.50 g of γ-methacryloxypropyltrimethoxysilane (New Moon silicone topic: KBM-503, SiO2 component 81.2%), 3.1 g of ultrapure water was added, After stirring for a time, the surface-treated silica fine particles methanol dispersion liquid 3 having a solid content concentration of 30.5% by weight was obtained.

Thereafter, solvent substitution was performed on propylene glycol monopropyl ether (PGME) using a rotary evaporator to obtain silica fine particle PGME dispersion (3) having a solid content concentration of 40.5% by weight.

Then, in Example 1, the same application | coating for transparent film formation as the solid content concentration 42.0 weight% was carried out similarly except having used the silica fine particle PGME dispersion liquid 3 instead of the silica particle PGME dispersion liquid of 40.5% weight% of solid content concentration. Liquid 6 was prepared.

Preparation of the transparent coating part base material 6

In Example 1, the transparent coating part base material 6 was similarly manufactured except having used the coating liquid 6 for formation of a transparent film. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesion, the soap resistance, the scratch resistance, the pencil hardness and the surface roughness of the obtained transparent coating part substrate were measured and the results are shown in the table.

Example 7

Preparation of the coating liquid 7 for transparent film formation

Preparation of P Doped Tin Oxide Fine Particles

13 g of ammonium nitrate and 20 g of 15% aqueous ammonia were added to 8060 g of pure water, and the mixture was stirred and heated to 50 ° C. Among them, a solution in which 1519 g of potassium stannate was dissolved in 4290 g of pure water was added by a roller pump over 10 hours. At this time, the pH was adjusted by adding 10% by weight of acetic acid to maintain the pH at 8.8. After the addition was completed, the mixture was maintained at 50 ° C for 1 hour, and then acetic acid having a concentration of 10% by weight was added, and the pH was lowered to 3.0. Subsequently, it was concentrated by ultrafiltration and taken out. The amount of liquid taken out at this time was 6000 g, and the solid content (SnO ₂ ) concentration was 12% by weight. In this slurry, 264 g of an aqueous solution of phosphoric acid having a concentration of 16% by weight was added and stirred for 0.5 hour. It was dried and calcined at 700 ° C. for 2 hours to prepare P-doped tin oxide fine particles. The average particle diameter of the obtained P dope tin oxide fine particle was 15 nm.

Preparation of Surface Treatment P Doped Tin Oxide Fine Particle Dispersions

217 g of P-doped tin oxide fine particles and 335 g of ion-exchanged water were added to a 2 L glass beaker, and then 50 g of a 20% by weight aqueous KOH solution was added. After separating the quartz beads and the dispersion liquid with a stainless steel wire (44 micrometers in diameter), and further mixing the solution of the quartz beads remaining on the wire mesh with 1560 g of ion-exchanged water and heat-treating the solution at 90 DEG C for 1 hour. After cooling to room temperature, adding 96 g of anion exchange resin and stirring for 1 hour, then separating the anion exchange resin, then adding 96 g of cation exchange resin, stirring for 1 hour, and then separating the cation resin to disperse the P-doped oxidized particulate aqueous dispersion (concentration of 10 wt%). %) Was obtained.

10 wt% of the concentration was added to 2000 g of the aquatic solution of P-doped tin oxide fine particles and 20.8 g of ethyl silicate (28.8% of ethyl silicate 28 SiO ₂ component from Tama Chemical Co.) as a coupling agent (weight ratio with P-doped tin oxide fine particles = 100/3) 2000 g of methanol was added and the mixture was stirred at 50 ° C. for 18 hours to carry out surface treatment. Thereafter, ethanol dispersion of P-doped tin oxide fine particles surface-treated with a silane coupling agent having a concentration of 30 wt% by solvent substitution with ethanol was prepared.

Thereafter, solvent substitution was performed on propylene glycol monopropyl ether (PGME) using a rotary evaporator to obtain a P-doped tin oxide fine particle PGME dispersion having a solid content concentration of 40.5% by weight.

Next, in Example 1, the coating liquid for transparent film formation of 42.0 weight% of solid content concentration was carried out similarly except having used P-doped tin oxide fine particle PGME dispersion liquid instead of the silica fine particle PGME dispersion liquid of 40.5 weight% of solid content concentration. (7) was prepared.

Preparation of the transparent coating part base material 7

In Example 1, the transparent coating part base material 7 was produced similarly except having apply | coated using the coating liquid 7 for transparent film formation, and using Barcoat # 20. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Comparative Example 1

Preparation of coating liquid (R1) for transparent film formation

The coating liquid (R1) for forming a transparent coating film having a solid content concentration of 42.0 wt% in the same manner as in Example 1, except that the acrylic silicon-based leveling agent (Nambon Chemical Co., Ltd .: Disparon NSH-8430HF) was not mixed. Was prepared.

Preparation of the transparent coating part base material R1

In Example 1, the transparent coating part base material R1 was similarly manufactured except having used the coating liquid R1 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Comparative Example 2

Preparation of coating liquid (R2) for transparent film formation

In Example 1, the coating liquid 2 for transparent film formation of 42.0 weight% of solid content concentration was produced similarly except mixing acrylic silicone type leveling agent (Nambon Chemical Co., Ltd. material; Disparon UVX-271). It was. As a result of measuring the molecular weight of the leveling agent, the average molecular weight was 4,000.

Preparation of the transparent coating part base material R2

In Example 1, the transparent coating part base material R2 was produced similarly except having used the coating liquid R2 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Comparative Example 3

Preparation of coating liquid (R3) for transparent film formation

In Example 1, the coating liquid (R3) for transparent film formation of 42.0% of solid content concentration was manufactured similarly except having mixed the acrylic glyco type leveling agent (Nambon Chemical Co., Ltd. product: Disparon UVX-2280). It was. As a result of measuring the molecular weight of the leveling agent, the average molecular weight was 35,000.

Preparation of the transparent coating part base material R3

In Example 1, the transparent coating part base material R3 was produced similarly except having used the coating liquid R3 for transparent film formation. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

[Comparative Example 4]

Preparation of coating liquid (R4) for transparent film formation

37.04 g of propylene glycol monopropyl ether dispersions of silica sol with a solid content concentration of 40.5% by weight, 12.00 g of dipentaerythritol hexaacrylate (DPE-6A manufactured by Kogyo Chemical Co., Ltd.) and dimethylol tricyclo Decanediacrylate 1.6-hexanedioldiacrylate (manufactured by Kogyo Chemical Co., Ltd .: Lightacrylate SR-238F) 3.00 g and an acrylic silicone leveling agent (Nambon Chemical Co., Ltd .: Disparon NSH-8430 HF) 30 g and a photopolymerization initiator (Ciba Japan Co., Ltd .: Irgacure 184, dissolved in PGME at 20% solids concentration) 4.50 g, PGME 3.46 g, and acetone 10.0 g are sufficiently mixed to form a transparent film having a solid concentration of 30% by weight. Coating liquid R4 was prepared.

Preparation of the transparent coating part base material R4

In Example 1, the transparent coating part base material R4 was similarly manufactured except having apply | coated using the coating liquid R4 for transparent film formation, and using Barcoat # 20. The film thickness of the transparent film was 6 micrometers.

The total light transmittance, the haze, the adhesiveness, the soap resistance, the scratch resistance, the pencil hardness, and the surface roughness of the obtained transparent coating part base material were measured and the results are shown in the table.

Claims (15)

In the coating liquid for transparent film formation which consists of a matrix formation component, metal oxide fine particles, and a solvent,
The coating liquid for transparent film formation containing acrylic silicone type resin whose average molecular weights are a range of 5,000-30,000 as a leveling agent, and content of a leveling agent is 0.001-7.2 weight% as solid content.
The method of claim 1, wherein the concentration of the matrix forming component is in the range of 1 to 59.9% by weight as solids, the content of the metal oxide fine particles is 0.025 to 48% by weight as solids, and the total solids concentration is in the range of 5 to 60% by weight. Coating liquid for transparent film formation
The metal oxide according to claim 1 or 2, wherein the metal oxide fine particles include silica, alumina, titanium oxide, zirconium oxide, tin oxide, titanium pentoxide, indium oxide or a composite oxide thereof, or a dopant. Coating liquid for forming a transparent film, characterized in that at least one fine particle selected from an oxide
The coating liquid for forming a transparent film according to claim 3, wherein the metal oxide fine particles are silica-based fine particles.
The coating liquid for forming a transparent film according to any one of claims 1 to 4, wherein the metal oxide fine particles are surface treated with an organosilicon compound.
The coating liquid for forming a transparent film according to any one of claims 1 to 5, wherein the metal oxide fine particles have an average particle size in the range of 5 to 300 nm.
It consists of a base material and the transparent film formed on the base material, The transparent film consists of a matrix component and metal oxide microparticles | fine-particles, Comprising an acrylic silicone resin with an average molecular weights of 5,000-30,000 as a leveling agent, Content of the said matrix component is solid content In the range of 20 to 99.5% by weight, and the content of the metal oxide fine particles is in the range of 0.5 to 80% by weight as a solid content.
8. The transparent coating part substrate according to claim 7, wherein the leveling agent content in the transparent coating is in a range of 0.02 to 12 wt% as solid content.
The metal oxide fine particle of claim 7 or 8, wherein the metal oxide fine particles are at least one selected from silica, alumina, titania, zirconia, tin oxide, titanium pentoxide, indium oxide or a complex oxide thereof, or an oxide including a dopant or a complex oxide. Transparent coating part base material characterized by fine particles or more
The transparent coating part substrate according to any one of claims 7 to 9, wherein the metal oxide fine particles are silica-based fine particles.
The transparent coating part substrate according to any one of claims 7 to 10, wherein the metal oxide fine particles are surface treated with an organosilicon compound.
The transparent coating part substrate according to any one of claims 7 to 11, wherein the average particle size of the metal oxide fine particles is in the range of 5 to 300 nm.
Of claim 7 to 12 according to any one of items, and is 60? 110 ° range of the contact angle (CA ₁₎ of the transparent film, then the surface of the clearcoat of saponification (Saponification) processing the contact angle (CA ₂₎ and Transparent coating part base material characterized in that the contact angle difference is 10 ° or less
The transparent film part substrate according to any one of claims 7 to 13, wherein the haze of the transparent film is 1.0% or less.
The transparent coating part substrate according to any one of claims 7 to 14, wherein the surface roughness Ra of the transparent coating is 20 nm or less.