JP2002030251A - Transparent coating containing flaky silica particles - Google Patents

Abstract

(57) [Problem] To provide transparency to an opaque cured coating film containing silica. SOLUTION: A flaky silica flake primary particle is oriented in parallel between planes and a plurality of flake-like silica secondary particles and a transparent organic polymer substance are formed on an opaque coating film containing a transparent organic polymer substance. A transparent coating is formed by forming an overcoat layer made of a transparent organic polymer or by performing a treatment such as reducing the particle size of the silica particles to a specific range or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substantially transparent cured coating film containing a secondary particle of foliar silica and an organic polymer substance, which is treated to impart transparency thereto. .

[0002]

2. Description of the Related Art The present inventors have previously made flaky silica flake primary particles substantially consisting of leaf-like silica secondary particles formed by superposing a plurality of flake-like silica particles with their planes oriented parallel to each other. A novel cured coating composed of flaky silica particles having a layered particle morphology and an organic polymer substance independently of each other has been proposed (Japanese Patent Application No. 11-351182).

[0003] The silica secondary particles having a specific particle morphology of a laminated structure contained in the coating film were first created by the present inventors, but the particles were made of acrylic resin or epoxy resin. When used in a conventional organic coating such as a urethane resin, the coating is excellent in water resistance, acid resistance, alkali resistance, weather resistance, etc. due to its unique particle form and its physical properties. Properties can be imparted. In addition, since the particles are basically excellent in self-film-forming property, they are oriented in the coating film and exist in a state of being stacked on each other, and thus impart hardness and adhesion to the substrate to the coating film.
For example, when the pencil hardness of a coating film of a normal organic paint is about B to 4B, when the silica secondary particles are blended, the hardness is improved to about H to 4H.

The silica secondary particles are used together with an organic ultraviolet shielding agent and an inorganic ultraviolet shielding agent such as titanium oxide, zinc oxide and cerium oxide to form a coating having an optical function such as an ultraviolet shielding function. A film can be formed.
In this case, since the silica secondary particles are excellent in orientation and are leaf-like silica particles having a laminated structure having a strong self-film-forming property itself, the particles such as titanium oxide particles are effectively supported in the coating film. , Oriented along the silica particles,
It is considered that a coating film having significantly improved optical characteristics is formed.

[0005] Similarly, the silica particles are converted into a material having a function of selectively transmitting light such as infrared absorption, a material having a fluorescent function such as a fluorescent pigment or a phosphor, a material having a photooxidation catalytic function,
By using it together with substances having deodorant function,
It is also possible to obtain a paint in which these functions are more effectively performed.

[0006] As described above, by blending the leaf-like silica secondary particles having a unique particle morphology of the laminated structure into the coating film, the water resistance and acid resistance of the coating film itself are greatly improved, and the oxidation resistance is improved. By greatly improving the orientation and dispersibility of the functional particles such as titanium particles in the coating film, the function of the functional particles is remarkably enhanced, so that the applicable range is extremely large.

[0007] Unfortunately, when the secondary particles of foliar silica are incorporated into the coating film, the transparency of the coating film itself may be reduced.

In general, there are many fields in which the coating film itself is required to be transparent. For example, substrates such as glass plates, plastic plates, steel plates, aluminum plates, concrete, mortar, wood, etc., or color bases applied on these substrates Highly transparent coatings (so-called clear coatings) having various functions formed on coatings and color hard coatings, etc. It is desirable.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to further improve the applicability of a coating film containing foliar silica secondary particles having excellent properties as described above, and to provide a coating film having a wider range as described above. An object of the present invention is to further enhance the transparency of the coating film in order to be able to be suitably applied to applications, and to provide a coating film with high transparency even when the mixing ratio of the silica particles is high.

[0010]

Means for Solving the Problems The present inventors have made intensive studies in view of the importance of the above-mentioned problems, and as a result, by treating the surface of the above-mentioned coating film with a transparent organic polymer material of the same or different type. Alternatively, as the secondary particles of the foliar silica to be blended, those having a specific range of an average particle diameter of less than 1 μm are used, and surprisingly, the water resistance, acid resistance, alkali resistance, and weather resistance of the coating film are surprisingly increased. It has been found that the transparency of the cured coating film can be significantly improved without impairing excellent properties such as properties. The present invention has been made based on such findings.

That is, according to the present invention, (1) secondary particles of flaky silica formed by laminating primary particles of flaky silica in parallel with each other with their planes oriented parallel to each other and a transparent organic polymer A substantially transparent cured coating, which is a coating containing a substance, wherein the coating has a transmittance of 70% or more of light having a wavelength of 500 nm in terms of a coating thickness of 50 μm. Is done.

Further, according to the present invention, (2) leaf-like silica secondary particles formed by laminating flake-like silica primary particles in parallel with each other and a plurality of sheets, and a transparent organic polymer A coating film containing a substance and a top coat layer of a transparent organic polymer material, wherein the transmittance of light having a wavelength of 500 nm in terms of a coating film thickness of 50 μm is 70.
%, Wherein the cured coating is substantially transparent.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The silica particles to be incorporated in the cured coating film of the present invention are secondary particles of flaky silica formed by laminating primary particles of flaky silica in parallel with each other with their planes oriented in parallel with each other. This has a particle structure of a laminated structure which exists independently of each other. The silica secondary particles are formed by overlapping scale-like primary particles.
The secondary particles cannot be identified by a scanning electron microscope (hereinafter abbreviated as SEM), and the SEM can identify only a plurality of leaf-like secondary particles which are oriented in parallel between planes and overlapped. And a transmission electron microscope (hereinafter referred to as TE
Abbreviated as M. When observed using (), the primary particles, which are ultrathin flake particles through which an electron beam partially passes, can be identified.

The bonding between the layers composed of the primary particles is extremely strong, and the flaky primary particles, which are constituent units thereof, are completely separated from the leaf-like secondary particles one by one. Separation is usually very difficult. However, in some cases, according to the method described later, it is possible to disintegrate into two or more thinner leaf-like silica secondary particles having a thinner overlap while maintaining the overlap.

The foliar silica secondary particles in the present invention are obtained by pulverizing tertiary aggregate particles (tertiary particles) of silica.

The silica tertiary aggregate particles have a SEM
As can be seen from the photograph, the leaf-like secondary particles overlap irregularly and have a large number of gaps (voids or pockets) created by this overlap, and apparently cabbage-like, onion-like, petal-like, bud-like. , Snail-shaped, etc.
It can take various forms depending on the state.

The silica tertiary aggregate particles can be preferably produced by the method previously proposed by the present inventors (JP-A-2000-72432).

That is, a method of hydrothermally treating a spherical or irregularly shaped silica hydrogel as a starting material in the presence of an alkali metal, wherein the silica tertiary aggregate particles silica-X and silica-Y of the present invention are used. With lower temperature and shorter time reaction without generating crystals such as quartz,
Moreover, it is a method that can be manufactured with high yield.

Here, the spherical silica hydrogel may be formed by solidifying a silica hydrosol into a spherical shape in a petroleum or other medium as has been known for a long time. As described in JP-B-48-13834, the silica / alkali molar ratio (SiO ₂
/ Me ₂ O (Me represents an alkali metal such as Na.))
An aqueous solution of an alkali silicate having a silica concentration of about 2 to 20% by mass and a mineral acid aqueous solution are mixed in a short time to form a silica sol having a pH of about 7 to 9 and simultaneously released into a gaseous medium. Then, it is manufactured by a method of gelling in the gas.

Using such a silica hydrogel as a starting material, hydrothermal treatment is performed by heating in a heating pressure vessel such as an autoclave or the like, to produce tertiary silica aggregate particles. In this case, the spherical silica hydrogel may be used as it is, but preferably, it is pulverized or coarsely pulverized to a particle size of 0.1.
A thickness of about 1 to 6 mm is desirable because stirring in the autoclave can be performed more effectively.

The hydrothermal treatment is performed in a temperature range of 150 to 220 ° C., preferably 160 to 200 ° C., in order to obtain a single phase such as silica-X or silica-Y in a short time.

The required duration of the hydrothermal treatment may vary depending on the temperature of the hydrothermal treatment and the presence or absence of seed crystals, but is usually about 3 to 50 hours, preferably about 5 to 40 hours.

The silica 3 thus obtained in the form of a water slurry
By crushing and dispersing the secondary aggregate particles by the specific method proposed by the present inventors, a water slurry of foliar silica secondary particles having a solid content of 1 to 30% by mass can be obtained. No. 11-351182).

That is, the silica tertiary aggregate particle slurry is washed with water and solid-liquid separated using a solid-liquid separation / washing device such as a belt filter or a filter cloth centrifuge, and then repulped with water if necessary. Composed of silica tertiary aggregate particles
A water slurry having an iO ₂ concentration of 1 to 30% by mass is supplied to a wet bead mill (disintegration device) such as a wet bead mill or a wet ball mill, which mechanically stirs at a high speed using a pulverizing medium, to produce scaly silica. The tertiary aggregate particles are crushed. Here, a wet bead mill using medium beads of 0.2 to 1.0 mm in diameter, such as alumina or zirconia, is particularly preferable in order not to pulverize and break the secondary particles of foliar silica.

Thus, substantially free of tertiary particles,
A plurality of flaky silica secondary particles in which the flake primary particles are oriented parallel to each other in planes are obtained as a slurry.

Alternatively, the slurry of the silica tertiary aggregate particles is dried by a medium fluidized bed drier to form a dry powder,
This may be wet-pulverized (crushed) in the same manner as described above to obtain a slurry of foliar silica secondary particles.

On the other hand, as a method for obtaining a dry powder of foliar silica secondary particles, in order to prevent the above-mentioned secondary particle slurry from agglomerating particles and obtain a good yield, the SiO ₂ concentration is adjusted to 0.1.
It is obtained by adjusting to 5% by mass, preferably 1 to 3% by mass and spray-drying. Alternatively, a dry powder of silica tertiary aggregate particles is combined with a dry pulverizing / classifying machine composed of a combination of a dry pulverizing function and a dry classifying function, for example, by combining both a jet mill and a high-speed rotary classifier or a wind classifier. When used, the average particle diameter is 0.001 to 10 μm, preferably 0.01 to 10 μm, more preferably 0.1 to 10 μm.
The particles may be continuously crushed into dispersed foliated silica secondary particles of about μm.

The basic physical properties of the foliated silica secondary particles in the present invention are as follows. The SiO ₂ purity of the silica in the silica secondary particles is 99.0% by mass or more. The pH is 6.0 to 8.0, and the spectrum of the X-ray diffraction is ASTM (American Society for American
Testing and Materials) (hereinafter simply referred to as an ASTM card) number 16-0380.
2θ = 4.9 °, 26.0 °, and 28.3 corresponding to
Silica-X and / or AST characterized by a main peak in °
2θ = 5.6 corresponding to the M card number 31-1233
It is a silica consisting of silica-Y characterized by main peaks at °, 25.8 ° and 28.3 °. Oil absorption (JIS K
5101) is 100 to 150 ml / 100 g.

When used in the present invention, the average particle size of the foliar silica secondary particles is from 0.001 to 10 μm, preferably from 0.01 to 10 μm, and more preferably from 0.1 to 10 μm.
It is about μm. Here, as a method of measuring the average particle size, a laser diffraction / scattering type particle size distribution measuring device (for example,
LA-920, manufactured by Horiba, Ltd., a dynamic light scattering particle size distribution analyzer (for example, LB-500, manufactured by Horiba, Ltd.)
Type) or a Coulter counter (for example, MA-II type manufactured by Coulter Electronics Co., Ltd.) or the like as appropriate according to the range of the particle diameter.

The secondary particles of foliar silica in the present invention are:
When observed by SEM, the thickness is 0.001 to
0.5 μm, the ratio of the longest length of the foliar silica secondary particles (plates) to the thickness (aspect ratio) is at least 5 or more, and the minimum length of the foliar silica secondary particles (plates) to the thickness Has an aspect ratio of 2 or more. The upper limit of the ratio of the longest length and the minimum length to the thickness of the foliar silica secondary particles is not particularly limited, but the former is preferably 300 or less, and the latter is preferably 150 or less.

When the pore distribution of the silica secondary particles was measured by the BET method (Bellsoap-28, manufactured by Nippon Bell Co., Ltd.), the pore volume was 0.05 to 0.15 ml / g.
The specific surface area is 30~80m ² / g.

It should be particularly noted that the pore distribution curve shows a sharp large peak at a pore diameter of 2 to 6 nm, especially around 3.5 to 4.0 nm.

As the optical properties, the refractive index of light of the silica secondary particles (observation by orthogonal Nicols using a deflection microscope by a sample powder immersion method) is 1.48 to 1.52.

The infrared absorption spectrum (FT-IR) of the silica (SiO _{2 at} room temperature without heat treatment)
Is 3600-3700 cm ^-1 , 3400-3500c
Silica having silanol groups each having one absorption band at m ^-1 . Further, the amount of silanol groups per specific surface area by the BET method has a large value of 50 to 70 μmol / m ² (several times that of silica gel). For this reason, when it is mixed with an aqueous emulsion of an organic polymer and applied on a substrate to form a coating film, the coating film can be imparted with hydrophilicity.

The saturated solubility of the secondary silica particles in an aqueous acid solution and aqueous alkali solution at 20 ° C. is low. That is, the dissolved SiO ₂ concentration is 0.008% by mass for a 10% by mass aqueous HCl solution, 0.006% by mass for ion-exchanged water, and 0% for a 5% by mass NaOH aqueous solution. It is 0.79% by mass with respect to an aqueous solution of 0.55% by mass and 10% by mass of NaOH, indicating that it has small solubility in both acids and alkalis and has acid resistance and alkali resistance. In particular, it has a very small solubility in an aqueous alkali solution as compared to silica gel or colloidal silica, and indicates that it has alkali resistance.

The cured coating film of the present invention is basically a coating film containing the secondary particles of foliar silica and a transparent organic polymer as described above.

The cured coating film of the present invention is formed by applying a curable composition comprising the above-mentioned secondary particles of leaf silica, a transparent organic polymer substance and a volatile liquid onto a substrate and drying the composition.

Examples of the transparent organic polymer include, for example,
Acrylic resin type, epoxy resin type, urethane resin type, styrene resin type, silicone resin type, fluororesin type and at least two or more of these are transparent resins such as copolymer resin type, and have a refractive index of light. , 1.3 to 1.6.

The volatile liquid is water and / or a volatile liquid other than water, for example, benzene, toluene, xylene, methyl isobutyl ketone, methyl ethyl ketone, ethyl acetate, butyl acetate, isopropyl alcohol, kerosene, gas oil and the like. Organic solvent.

The curable composition obtained by uniformly mixing the above components is applied to a substrate (metal, glass, ceramics, plastic, slate, hardened cement, wood, paper, etc.), dried and dried on the substrate. Form a cured coating,
dry. The drying temperature is from room temperature to 200 ° C, preferably from room temperature to 100 ° C, more preferably from room temperature to 80 ° C.
° C. Here, the SiO ₂ concentration in the curable composition is:
It is preferably from 1 to 80% by mass.

The cured coating film of the present invention formed on the substrate as described above has a pore volume of 0.10 ml / pore.
g or more, and is basically an opaque coating film.

The cured coating film of the present invention has a wavelength of 5 μm in terms of a coating thickness of 50 μm.
It is substantially transparent and has a transmittance of 00 nm light of at least 70% or more, preferably 80% or more, and more preferably 90% or more. The means for imparting this transparency is not particularly limited, but one of the preferred means is to impart transparency by providing an overcoat layer made of a transparent organic polymer substance. Here, “wavelength 5 converted to 50 μm of coating film thickness”
"The transmittance of light of 00 nm is at least 70% or more."
It means that the transmittance of light having a wavelength of 500 nm is at least 70% or more when converted to a coating film thickness of 50 μm. The conversion can be performed by the following equation (2).

In the case of a cured coating film provided with an overcoat layer,
Here, “converted to a coating thickness of 50 μm” means that the thickness of the cured coating film excluding the overcoat layer is converted to a thickness of 50 μm.

This overcoat layer is formed by forming a transparent organic polymer substance of the same type or different type (for example, acrylic resin, epoxy resin, urethane resin, styrene resin, Transparent resins such as silicone resins, fluororesins, and at least two or more of these resins, preferably those having a light refractive index of 1.3 to 1.6) and volatility It is performed by applying and drying a curable composition composed of a liquid (water or the above-mentioned organic solvent) for use in paints and coating agents.

The effect of the present invention is confirmed by a photograph showing a state in which the surface of a paper having characters printed on the surface is covered with a transparent quartz glass plate on which a cured coating film having transparency according to the present invention is formed. be able to. For example, if the right half of the glass plate is coated with a silica-containing coating film (mixed coating film), and the left half is a state where the coating film has been subjected to the clearing treatment in the present invention, the silica-containing cured coating film remains as it is. In the case of (right), the characters on the underlying paper are covered with a white silica-containing coating film, and are faint or almost invisible. However, when the transparency processing in the present invention is performed (left), It is recognized that the entire silica-containing coating film is made transparent so that the characters can be clearly read.

Although the detailed mechanism by which the overcoat layer imparts transparency to the basically opaque cured coating film is unknown, it probably consists of the above-mentioned foliar silica secondary particles and a transparent organic polymer. The pores in the cured coating film are impregnated and filled with the same or different transparent organic polymer material forming the above-mentioned overcoat layer, thereby reducing the volume of the pores and / or improving the surface of the coating film. It is considered that a cured coating film having transparency and imparting gloss is obtained mainly by two actions, that is, reduction of light scattering due to reduction of fine irregularities. Incidentally, the pores in such a cured coating film are presumed to be formed because the presence of the silica secondary particles in the coating film does not completely shrink after the solvent is removed during drying of the coating film. It is presumed that the fine irregularities on the surface are formed because the silica secondary particles have a particle diameter on the order of μm (measured by a Coulter counter) and remain on the coating film surface.

The foliar silica 2 relative to the total solid content of the foliar silica secondary particles and the transparent organic polymer substance in the cured coating film
The solid content ratio of the secondary particles is 90% by mass or less, preferably 8% by mass.
0 mass% or less, more preferably 70 mass% or less, and 1 mass% or more. If it exceeds 90% by mass, the pores in the cured coating film containing the foliar silica secondary particles and the transparent organic polymer substance are made of the same or different transparent polymer substance,
Even when substantially filled, the transparency of the cured coating does not increase sufficiently.

Further, a mechanism for filling pores in a cured coating film composed of secondary particles of foliar silica and a transparent organic polymer substance with the same or different kinds of transparent organic polymer substances to reduce the volume of the pores. In order to make the effective value, the pore volume in the cured coating film after providing the overcoat layer is 0.10 ml /
g or less, more preferably 0.1 g or less.
More preferably, it is not more than 05 ml / g. If the pore volume exceeds 0.10 ml / g, the transparency of the cured coating film will not be sufficiently high.

The pore volume is determined as follows, where V ₁ is the measured pore volume (overall) after overcoating. That is, a coating film composed of leaf-like silica secondary particles and a transparent organic polymer provided directly on the substrate surface (this may be referred to as a “mixed coating film” or a “silica-containing coating film” in the present invention). Let L ₁ be the thickness of
Assuming that the total coating thickness after overcoating on this is L ₂ , the overcoating film composed of only this organic polymer substance has no pores because it does not contain silica particles, and its pore volume is Since it can be regarded as substantially zero, the pore volume V ₂ of the mixed coating film itself after the top coating can be converted from V ₁ by the formula (1).

V ₂ = V ₁ × (L ₂ / L ₁ ) (1) The pores in the cured coating film (mixed coating film) composed of the foliar silica secondary particles and the transparent organic polymer substance are of the same type. Or, when providing an overcoat layer made of a different kind of transparent organic polymer substance, after coating and drying, if the thickness of the newly formed coating film is large, the cured coating film as the overcoat layer is clearly formed. It is formed. However, for the purpose of reducing the pore volume by impregnating and filling the organic polymer substance into the pores, or reducing the fine irregularities on the coating surface, a thick cured coating film is formed as an overcoat layer. This is not necessarily essential, and the thickness of the coating film may be extremely thin, and may be substantially close to a single-layer coating film. That is, it is not essential to form a thick top coat, and a very thin coat may be used as long as the thickness is sufficient to achieve the above mechanism, and the thickness is about 0.001 to 50 μm. Preferably, there is.

Also, as described above, even when a cured coating film of a somewhat thick overcoat layer is formed, the curable coating film of this overcoat layer is made of a transparent organic polymer substance. Basically, it is very transparent. Therefore, the transparency of the entire coating film is substantially determined by the transparency of the cured coating film (mixed coating film).

The presence of the overcoat layer in the cured coating film of the present invention can be confirmed by observing the fracture surface of the coating film with an electron microscope (SEM-ED).
X analysis of carbon and silicon maps) can be clearly confirmed by detecting the thickness of both layers and the presence of a layer substantially free of silica. In addition, the fact that the foliar silica secondary particles are contained in the cured coating film means that the surface of the coating film is incinerated by low-temperature oxygen plasma to remove only the organic polymer substance, and then the surface is subjected to SEM. It can be confirmed by observation. Thus, when the coating film is actually ashed and removed, the SEM clearly confirms that the silica secondary particles are present in the coating film in a stacked and oriented state as expected. The particle size of the silica secondary particles remaining after the incineration treatment can be measured by the method described above.

The above method (hereinafter sometimes referred to as “overcoating method”) is a method applicable to silica secondary particles having a wide particle size range. While maintaining the laminated structure of (i.e., while maintaining characteristics such as film forming properties of the particles), the effect of the above-mentioned overcoating method can be further enhanced by reducing the particle size, and in some cases, It has been found that even when used alone without applying the overcoating method, satisfactory transparency can be maintained. However, it should be noted that simply reducing the particle size of the silica secondary particles to fine particles as in the prior art does not make much sense in the present technology. This is a foliate 2
This is because the layered structure of the secondary particles, that is, the leaf-like property (high aspect ratio) is destroyed, and the most essential properties such as film-forming properties are greatly impaired.

The present inventors have proposed a wet pulverizing apparatus using a pulverizing medium such as zirconia beads having a diameter of 0.2 to 1.0 mm as described above in order to maintain and refine the laminated structure of the secondary particles of foliar silica. (Pulverizer) was found to be preferable. That is, in the case where the silica tertiary aggregate particle slurry is supplied to the above-mentioned crushing device and continuously crushed, in the method described above, secondary particles are obtained by passing once (one pass). However, this may be circulated. In general, the number of circulation passes is preferably plural, especially three or more. In the case of a single pass without circulation (one pass), the residence time of one pass may be made sufficiently long.

Surprisingly, according to this crushing method, the particles are refined while substantially maintaining the laminated structure. This is because the mechanism of miniaturization employed here is mainly from a thicker laminated structure to particles with a thinner laminated structure, or the laminated thickness does not change and the particle length direction It is performed by crushing along or across the length direction, etc.In any case, it is not a mechanism that crushes particles into fine particles by mechanical crushing based on strong impact force, so basically the laminated structure is , Is considered to be retained. In fact, when the silica secondary particles after refinement are observed by SEM and / or TEM, it is not recognized that a substantial change occurs in the laminated structure itself. In addition, the fact that the film forming properties are not impaired
This is as shown in the examples described later.

As described above, finely divided silica secondary particles can be obtained while maintaining the laminated structure. However, the particle size of the finely divided particles is preferably at least less than 1 μm, more preferably 0.001 μm That is all.

By using such secondary particles of leaf-like silica crushed to an average particle size of less than 1 μm, a cured coating film having a transmittance of 70% or more for light having a wavelength of 500 nm is obtained. What can be said is that, as already mentioned, the pore structure in the coating film is reduced and / or the fine irregularities on the coating film surface formed in the same manner are reduced, so that light can be reduced. It is presumed to be due to reduced scattering.

The method of using such finely divided leaf-like silica secondary particles (hereinafter, sometimes referred to as “fine-refining method”) may be used alone without applying the above-mentioned overcoating method. However, it is also possible to use this in combination with the overcoating method, but when used at least alone, the particle size is
Preferably it is less than 1 μm.

Incidentally, just in case, when the miniaturization method is used alone, since L ₁ = L ₂ in the equation (1),
V ₂ = V ₁ .

(Evaluation Method of Transparency of Cured Coating Film) In the present invention, the evaluation of transparency of the cured coating film is performed by the following method. Quartz glass plate (100mm × 100mm × 2m
m) is prepared and a bar coater coating method (JISK 540) is used.
In step 0), the curable composition is applied to one surface of the quartz glass plate using a bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. At this time, the amount of coating (in terms of solid content) and the thickness of the coating film are measured.

The light transmittance of the test piece at each wavelength of light is measured by a self-recording spectrophotometer (U-4000, manufactured by Hitachi, Ltd.).

In the case where the coatings of the same formulation have different coating thicknesses, in order to compare the light transmittance at the same coating thickness, it is assumed that the coatings are uniform in the thickness direction, and the spectrophotometric method is used. It is calculated and converted by equation (2) according to Beer's rule which is a basic rule. That is,

Log ₁₀ (I ₀ / I) = K * L (2) where I ₀ : intensity of incident light I: intensity of light after passing through the cured coating L: thickness of the cured coating (μm) ) K: constant (constant if the coating thickness is different for coating films of the same formulation)

In the present invention, the curable composition comprising the secondary particles of foliar silica, a transparent organic polymer substance and a volatile liquid is contained in a range not to impair the transparency of the final cured coating film. Other functional material fine particles (for example, titanium oxide, zinc oxide having an ultraviolet shielding function as an optical function,
Fine particles such as cerium oxide, iron oxide, and zirconium oxide) can be added and used in combination.

Thus, when characters, photographs, images, and the like are printed on the substrate with an organic dye or the like, a transparent cured coating containing, for example, the silica secondary particles of the present invention and titanium oxide, etc., is printed on the printed surface. By forming the film, the aesthetics of the printed image and the like are not impaired at all, and the color of the image printed on the substrate for a long time does not fade even when exposed to sunlight outdoors. Examples of such a substrate include, but are not particularly limited to, wall surfaces, floor surfaces, signboards, tent structures, snowboards, skis, golf balls, helmets and the like of architectural structures.

[0067]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

In the following examples, the pore volume of the cured coating film was measured by a nitrogen adsorption method (hereinafter referred to as a BET method) pore distribution measuring device (Bellsoap 28 type, manufactured by Nippon Bell Co., Ltd.).

The light transmittance of the cured coating film was determined by measuring the transmittance of a cured coating film formed on a quartz glass plate with respect to light having a specific wavelength by a self-recording spectrophotometer (U-4 manufactured by Hitachi, Ltd.).
000 type).

[Synthesis Example 1] (Production of tertiary aggregated silica particles using hydrogel as starting material) A silica hydrogel as a starting material was prepared as follows using sodium silicate as an alkali source. SiO ₂ / N
a ₂ O = 3.0 (molar ratio), 2,000 ml / min of an aqueous solution of sodium silicate having an SiO ₂ concentration of 21.0% by mass
And a sulfuric acid aqueous solution having a sulfuric acid concentration of 20.0% by mass are introduced into a container provided with a discharge port through separate inlets, and are mixed instantaneously and uniformly. Was adjusted to 7.5 to 8.0, and the silica sol solution uniformly mixed was continuously discharged into the air from the discharge port. The released liquid became spherical droplets in the air, and gelled in the air while flying in a parabola for about 1 second. At the drop point, leave an aging tank filled with water,
Dropped here and aged.

After aging, the pH was adjusted to 6, and the mixture was sufficiently washed with water to obtain a silica hydrogel. The obtained silica hydrogel particles have a spherical particle shape and an average particle diameter of 6
mm. SiO ₂ in the silica hydrogel particles
The mass ratio of water to mass was 4.55 times, and the residual sodium in the silica hydrogel particles was 110 ppm.
Met.

The above silica hydrogel particles were roughly pulverized to an average particle diameter of 2.5 mm using a double roll crusher and used in the next hydrothermal treatment step.

In a 50,000 ml autoclave (electrically heated, with anchor-type stirring blades), the total Si in the system was
The silica hydrogel having a particle diameter of 2.5 mm (SiO ₂ 18% by mass) so that the O ₂ / Na ₂ O molar ratio is 12.0.
23.7 kg and sodium silicate aqueous solution (SiO ₂ 2
8.75% by mass, 9.3% by mass of Na ₂ O, SiO ₂ / N
5.5 kg of a ₂ O = 3.17 (molar ratio) was added, and 10.7 kg of ion-exchanged water was added thereto, and a hydrothermal treatment was performed at 185 ° C. for 8 hours while stirring at 50 rpm. The total silica concentration in the system was 15% by mass as SiO ₂ .

The slurry after the hydrothermal treatment was subjected to filtration and water washing using a filter cloth type vertical centrifugal separator (Model TU-18, manufactured by Toko Kikai Co., Ltd.) to give a solid water content of 69.7% by mass (solid content concentration). 3
0.3% by mass) of a silica wet cake.

Water is added to the wet cake and repulped.
After a slurry of silica having a SiO ₂ concentration of 7.0% by mass was formed, a medium fluidized bed dryer (Okawara Seisakusho Co., Ltd., SFD-M)
4. INI type) and dried at a hot air temperature of 300 ° C.
6 kg of dry fine powder was obtained.

The product phase of the resulting fine powder was identified by the powder X-ray diffraction spectrum. As a result, the X-ray diffraction spectrum of 2θ = 4.9 ° and 26.0 ° corresponding to ASTM card No. 16-0380 was obtained. In addition to the main peak of silica-X characterized by the main peak, peaks corresponding to ASTM card numbers 31-1235 and 37-0386 were observed.

The oil absorption of this fine powder (JIS K5
When 101) was measured, it was 110 ml / 100 g.

When the morphology of the formed particles was observed by TEM, it was observed that the scale-shaped flake primary particles were oriented parallel to each other between the planes, and a plurality of sheets were overlapped to form leaf-like silica secondary particles. Was.

On the other hand, when the morphology of the formed particles was observed by SEM, the primary particles could not be identified, and the particles were observed as if the secondary particles of foliar silica were primary particles. The shape of the leaf-like particles was scaly, and it was observed that the tertiary silica aggregate particles having a large number of gaps (voids or pockets) were irregularly overlapped and formed. This is the silica tertiary aggregate particle in the present invention.

This leaf-like particle (TEM) observed by SEM
The average thickness of the part corresponding to the secondary particles) is 0.06 μm
On the other hand, the average maximum length of the plate with respect to the thickness is 5.4.
In μm, the aspect ratio was 90, the average minimum length of the plate was 1.6 μm, and the aspect ratio was 27.

The average particle diameter of this fine powder (silica tertiary aggregate particles) was measured using a Coulter counter (MAII type, manufactured by Coulter Electronics Co., Ltd., aperture tube diameter 50).
μm (same in the following synthesis examples), it was 6.1 μm.

Further, when the amount of crystalline free silicic acid of the fine powder was measured by X-ray diffraction analysis, it was found to be below the detection limit (2% or less).

[Synthesis Example 2] (Production of tertiary aggregated silica particles using hydrogel as starting material) A silica hydrogel as a starting material was prepared as follows using NaOH as an alkali source. SiO ₂ / Na ₂ O =
A sodium silicate aqueous solution having a concentration of 3.0 (molar ratio) and an SiO ₂ concentration of 21.0 mass% and a sulfuric acid aqueous solution having a sulfuric acid concentration of 20.0 mass% were separately placed in a container provided with a discharge port. The liquid introduced from the inlet is instantaneously mixed uniformly, and the pH of the liquid discharged into the air from the outlet is 7.5 to 7.5.
The flow rate ratio of the two liquids was adjusted so as to be 8.0, and the uniformly mixed silica sol liquid was continuously discharged into the air from the discharge port. The released liquid became spherical droplets in the air, and gelled in the air while flying in a parabola for about 1 second. An aging tank filled with water was placed at the dropping point, and the ripening tank was dropped and ripened.

After aging, the pH was adjusted to 6, and the mixture was sufficiently washed with water to obtain a silica hydrogel. The obtained silica hydrogel particles have a spherical particle shape and an average particle diameter of 6
mm. SiO ₂ in the silica hydrogel particles
The mass ratio of water to mass is 4.38 times, and the residual sodium in the silica hydrogel particles is 112 ppm.
Met.

The silica hydrogel particles were coarsely pulverized to an average particle size of 2.5 mm using a double roll crusher and used in the next hydrothermal treatment step.

In a 5000 ml autoclave (electrically heated, with anchor type stirring blades), the total SiO 2 in the system was added.
2688 g of the above silica hydrogel having a particle diameter of 2.5 mm (18.6% by mass of SiO ₂ ) and an aqueous solution of sodium hydroxide (NaOH) so that the molar ratio of ₂ / Na ₂ O is 11.0.
126 g of 48.5 mass%), 1186 g of ion-exchanged water was added thereto, and 0.5 g of a seed crystal was added thereto.
Hydrothermal treatment was performed at 180 ° C. for 12 hours while stirring at rpm. The total silica concentration in the system was 12.5 as SiO _2.
% By mass.

The slurry after the hydrothermal treatment was subjected to filtration water washing using a filter cloth type vertical centrifugal separator (Model TU-18, manufactured by Toko Kikai Co., Ltd.) to give a solid water content of 66.7% by mass (solid content concentration). 3
(3.3% by mass) of silica was obtained.

[0088] Water is added to the above wet cake and repulped.
After a slurry of silica having a SiO ₂ concentration of 7.0% by mass was formed, a medium fluidized bed dryer (Okawara Seisakusho Co., Ltd., SFD-M)
INI type) and dried at a hot air temperature of 300 ° C.
8 g of a dry fine powder were obtained.

The generated fine powder was identified by the powder X-ray diffraction spectrum to identify the generated phase.
ASTM card number 31-
In addition to the main peak of silica-Y characterized by main peaks of 2θ = 5.6 ° and 25.8 ° corresponding to 1233, AST
Peaks corresponding to M card numbers 35-63 and 25-1332 were observed.

The oil absorption of this fine powder (JIS K5
When 101) was measured, it was 100 ml / 100 g.

When the morphology of the formed particles was observed with a TEM, it was observed that the scale-shaped flake primary particles were oriented parallel to each other in planes, and that a plurality of sheets overlapped to form leaf-like silica secondary particles. Was.

On the other hand, when the morphology of the formed particles was observed by SEM, the primary particles could not be identified, and were observed as if the secondary particles of foliar silica were primary particles. The shape of the leaf-like particles was scaly, and it was observed that the tertiary silica aggregate particles having a large number of gaps (voids or pockets) were irregularly overlapped and formed.

The leaf-like particles (T
In EM, the average thickness of the portion corresponding to the secondary particles) is 0.07
For μm, the average maximum length of the plate for that thickness is:
At 6.0 μm, the aspect ratio was 86, the average minimum length of the plate was 1.8 μm, and the aspect ratio was 26.

The average particle size of the fine powder was measured using a Coulter Counter (MA, manufactured by Coulter Electronics Co., Ltd.).
It was 6.5 μm when measured using Type II).
Furthermore, when the amount of crystalline free silicic acid of the fine powder was measured by X-ray diffraction analysis, it was found to be below the detection limit (2% or less).

[Synthesis Example 3] (Production of slurry-like foliar silica secondary particles from wet cake of Synthesis Example 1) 1000 g of wet cake after filtration and washing with a centrifuge shown in Synthesis Example 1 (solid content concentration: 30.3% by mass)
020 g was added and repulped to prepare a silica slurry having a solid content of 15% by mass. In this slurry state,
The average particle size by a Coulter counter was 7.2 μm, and the viscosity by a B-type viscometer was 0.010 Pa · s.

Next, this slurry was mixed with a medium stirring bead mill (Dynomill KD, manufactured by Shinmaru Enterprises Co., Ltd.).
L-PILOT A type (vessel capacity: 1.4 L, diameter: 0.5 mm, filled with 80% zirconia beads: 80%)) is passed once at a shaft rotation speed of 3,400 rpm at a flow rate of 30 L / h to crush and disperse silica tertiary aggregate particles. Was performed.

The average particle diameter of the fine particles in the slurry after the crushing and dispersing was 1.6 μm as measured by a Coulter counter. The viscosity of the slurry was measured with a B-type viscometer and found to be 0.13 Pa · s.

Next, in order to examine the physical properties of the dried leaf-like silica secondary particles close to the state of the fine particles in the slurry, a dry powder was obtained by the following method.

Since the slurry has a peculiar property that it is extremely easily coagulated by drying, in order to obtain a monodispersed dry powder, a water slurry having a very low concentration is dried while preventing coagulation. There is a need.

That is, the slurry (solids concentration 15
Water), and the slurry concentration was adjusted to a solid concentration of 0.3% by mass.

The slurry was supplied using a small spray dryer (GA32, manufactured by Yamato Scientific Co., Ltd.) at a slurry supply rate of 1.7 ml / min and a spray pressure of 0.3 MPa.
(G), spray drying was performed at a hot air temperature of 130 ° C. to obtain a dry fine powder.

The average particle size of the obtained dry fine powder measured by a Coulter counter was 1.9 μm.

When this fine powder was observed by SEM, substantially no silica tertiary aggregate particles were observed.
It has been found that the foliated silica secondary particles of the present invention are substantially composed.

The product phase was identified by powder X-ray diffraction spectrum in consideration of this fine powder. As a result, 2θ = 4.9 ° and 26.0 corresponding to ASTM card No. 16-03380 were obtained as X-ray diffraction spectrum. In addition to the main peak of silica-X, which is characterized by the main peak of 該当, peaks corresponding to ASTM card numbers 31-1235 and 37-0386 were recognized, and it was confirmed that the peaks were the same as those before crushing.

Observation of the morphology of the formed particles by TEM showed that the scale-like flake primary particles were oriented parallel to each other in planes, and that a plurality of the flake-like primary particles were overlapped to form the foliar silica secondary particles of the present invention. Was observed.

The fine powder was embedded in an epoxy resin, and an ultra-thin section was prepared with an ultramicrotome.
When observed at M, the thickness of the primary particles was 1 to 10 nm.
It turned out to be extremely thin.

The fine powder had a pore volume of 0.12 ml / g and a specific surface area of 65 m ² / g by a BET method pore distribution measuring apparatus (Bellsoap 28, manufactured by Nippon Bell Co., Ltd.).
In the pore distribution curve, a sharp large peak in the mesopore region was observed around 3.6 nm. Further, an infrared absorption spectrum of the fine powder (FT-IR51, manufactured by Nicole Japan)
0) 3600-3700 cm ^-1 , 3400
Silanol groups having one absorption band at ~ 3500 cm ^-1 were observed.

The amount of the silanol group (SiOH) is
From the difference between the loss on drying at 120 ° C. for 2 hours and the loss on heating at 1200 ° C. for 3 hours (W mass%), silanol groups per unit mass of silica (SiOH) = W × 111.
According to a calculation formula of 1.1 (μmol / g), 36
It was 50 μmol / g, which was a large value of 56.2 μmol / m ² per specific surface area according to the BET method.

The heat resistance was measured under air atmosphere at 500
At ~ 1000 ° C, no particular change was observed by observation with a scanning electron microscope.

20 to aqueous acid solution and aqueous alkali solution
For saturated solubility at 0 ° C., the dissolved SiO ₂ concentration is 1
0.008% by mass with respect to 0% by mass HCl aqueous solution,
0.006% by mass, 5% by mass with respect to ion-exchanged water
The content was 0.55% by mass with respect to the NaOH aqueous solution and 0.79% by mass with respect to the 10% by mass NaOH aqueous solution. Particularly with respect to alkali resistance, for example, the solubility was very small as compared with silica gel (in the case of silica gel, the solubility was 6 even in a 3% by mass NaOH aqueous solution.
5% by mass. ).

[Synthesis Example 4] (Production of secondary particles of slurry-like foliar silica from wet cake of Synthesis Example 2) Synthesis Example 3 using wet cake after filtration and washing with a centrifuge shown in Synthesis Example 2 In the same manner as described above, a medium stirring bead mill (manufactured by Shinmaru Enterprises Co., Ltd., Dynomill KD
L-PILOT A type (vessel capacity: 1.4 L, diameter: 0.5 mm, filled with 80% zirconia beads: 80%)) is passed once at a shaft rotation speed of 3,400 rpm at a flow rate of 30 L / h to crush and disperse silica tertiary aggregate particles. And a water slurry of foliar silica secondary particles having a solid content of 15% by mass was obtained.

The average particle size of the fine particles in the crushed and dispersed slurry, as measured by a Coulter counter, was 1.7 μm. The viscosity of this slurry was measured with a B-type viscometer, and was 0.11 Pa · s.

[Synthesis Example 5] (Production of slurry-like secondary particles of foliar silica having a particle size of less than 1 μm from the wet cake of Synthesis Example 1) The wet cake after filtration and washing with a centrifuge shown in Synthesis Example 1 was added to the wet cake. Using a silica tertiary aggregate water slurry adjusted to a solid content concentration of 14% by mass by adding water, a medium stirring bead mill (Dynomill K, manufactured by Shinmaru Enterprises Co., Ltd.)
DL-PILOT A type (vessel capacity 1.4 L, diameter 0.5 mm, filled with 70% zirconia beads 70%)), 3 passes at a shaft rotation speed of 3400 rpm and a flow rate of 10 L / h, and disintegration and dispersion of silica tertiary aggregate particles And a water slurry of foliar silica secondary particles having a solid content of 14% by mass was obtained.

The average particle size of the fine particles in the slurry after crushing and dispersing was measured by a laser diffraction / scattering type particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.) to be 0.54 μm.
m. The viscosity of this slurry was measured with a B-type viscometer, and was 0.5 Pa · s.

Further, when the silica particles in the slurry were observed by SEM, the average particle diameter obtained in Synthesis Example 3 was 1.6 μm.
m silica secondary particles and the particle morphology observed by SEM are:
Little difference was observed.

Example 1 20 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 3, and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 10g (silica: resin = 1: 1 in terms of solids) of clear type paint, trade name Adekabon Titer HUX-350, solid content concentration 30% by mass) is put into a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Next, a quartz glass plate (100 mm × 100
mm × 2 mm, the same in the following examples. ) Is prepared and, using a bar coater coating method (JIS K5400), #
The curable composition was applied to one surface of the quartz glass plate using an 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount is about 1
The thickness of the coating film after drying at 8 g / m ² was about 30 μm.
The appearance of the coating was opaque and dull.

On the above-mentioned cured coating film, a urethane resin-based aqueous emulsion paint (clear type paint manufactured by Asahi Denka Kogyo KK, trade name: Adecabon Titer HUX-350, solid content concentration: 30% by mass) was coated with a # 20 bar coater. (Eto Kiki Co., Ltd.), and dried at room temperature to obtain a test piece.
The total coating amount of the entire coating film is about 24 g / m ² in terms of solids,
The total thickness of the entire cured coating film after drying (total thickness of the silica-containing coating film and the overcoat layer; hereinafter, the same in Examples 1 to 8) was about 40 μm.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.032 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
43 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film (silica-containing coating film + overcoat layer) formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured, and the transmittance was 98.85. %. Beer
The transmittance was calculated to be 98.09% when the silica-containing coating layer (mixed coating layer) was converted to a coating film thickness of 50 μm using the equation (2).

Example 2 24 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 3 and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 8g (silica: resin = 6: 4 in terms of solids) in a beaker, and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount is about 18 g / m ^{2 in} terms of solids, and the thickness of the coating film after drying is about 30 μm
Met. The appearance of the coating was opaque and dull.

On the above-mentioned cured coating film, a urethane resin-based aqueous emulsion paint (clear type paint manufactured by Asahi Denka Kogyo KK, trade name: Adecabon Titer HUX-350, solid content concentration: 30% by mass) was coated with a # 20 bar coater. (Eto Kiki Co., Ltd.), and dried at room temperature to obtain a test piece.
The total coating amount of the entire coating film is about 24 g / m ² in terms of solids,
The total coating thickness of the entire coating after drying was about 40 μm.

When the pore volume of this cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.014 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 19 ml / g. The appearance of the coating film was transparent and had high gloss.

The cured coating film formed on the quartz glass plate
When the transmittance of light with respect to light having a wavelength of 500 nm was measured, the transmittance was as high as 98.97%. When the transmittance of the silica-containing coating layer (mixed coating layer) in the case of a coating thickness of 50 μm was calculated from the equation (2) using the Beer rule, the transmittance was 98.29%.

Example 3 32 g of a 15% by mass solids concentration slurry (average particle size 1.6 μm) treated with a medium stirring bead mill described in Synthesis Example 3 and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 4g (silica: resin = 8: 2 in terms of solid content) of 4 g (solid content conversion: silica: resin = 8: 2) is put into a beaker, and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount was about 30 gm after drying about 18 g / m ^{2 in} terms of solids. The appearance of the coating was opaque and dull.

On the above-mentioned cured coating film, a urethane resin-based water-based emulsion paint (clear type paint manufactured by Asahi Denka Kogyo KK, trade name: Adecabon Titer HUX-350, solid content concentration: 30% by mass) was coated with a # 20 bar coater. (Eto Kiki Co., Ltd.), and dried at room temperature to obtain a test piece.
The total coating amount of the entire coating film is about 24 g / m ² in terms of solids,
The total coating thickness of the entire coating after drying was about 40 μm.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.071 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 95 ml / g. The appearance of the coating film was transparent and had high gloss.

The results were obtained by using a transparent quartz glass plate on which a transparent cured coating film of the present invention was formed on the surface of a paper on which a character string (a character string of a 24-point Gothic alphabet) was printed. This was confirmed by a photograph showing the covered state. That is, a silica-containing coating is applied to the right half of the quartz glass plate, and the silica-containing coating is left as it is when the coating is subjected to the transparent treatment according to the present invention on the left half ( In (right), the characters printed on the background are opaque and can only be seen faintly. However, in the case of transparency processing (left), the entire coating film is transparent and each character can be clearly read. confirmed.

Next, when the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured, the light transmittance was as high as 94.46%. When the transmittance of the silica-containing coating layer (mixed coating layer) with a coating thickness of 50 μm was calculated from the equation (2) using the Beer rule, the transmittance was 90.94%.

Example 4 20 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 3 and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 10g (silica: resin = 1: 1 in terms of solids) of clear type paint, trade name Adekabon Titer HUX-350, solid content concentration 30% by mass) is put into a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount was about 18 g / m ^{2 in} terms of solids, and the thickness of the coated film after drying was about 30 μm. The appearance of the coating was opaque and dull.

Next, an oil-based fluororesin emulsion paint (clear type paint, solvent xylene, trade name: Lumiflon LF-200, trade name: Lumiflon LF-200, trade name: Lumiflon LF-200, solid content concentration: 60% by mass) was coated on the above-mentioned cured coating film by # 20. It was applied using a bar coater (manufactured by Eto Kikai Co., Ltd.) and dried at room temperature to obtain a test piece. The total coating amount of the whole coating film is about 24 g /
m ² , the total coating thickness of the entire coating after drying was about 40 μm.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.033 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 44 ml / g. The appearance of the coating film was transparent and had high gloss.

The cured coating film formed on the quartz glass plate
When the transmittance of the light with respect to the light having a wavelength of 500 nm was measured, the transmittance was as high as 98.76%. The transmittance when the coating thickness of the silica-containing coating layer (mixed coating layer) was 50 μm was calculated from the equation (2) using the Beer's rule. The transmittance was 97.94%.

Example 5 20 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 3, and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 10g (silica: resin = 1: 1 in terms of solids) of clear type paint, trade name Adekabon Titer HUX-350, solid content concentration 30% by mass) is put into a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount was about 18 g / m ^{2 in} terms of solids, and the thickness of the coated film after drying was about 30 μm. The appearance of the coating was opaque and dull.

Next, an epoxy resin was placed on the cured coating film.
Fat-based water-based emulsion paint (clearer manufactured by Asahi Denka Kogyo Co., Ltd.)
Ip paint, trade name Adeka Resin EM-0460, solid content
Concentration of 45% by mass) with a # 20 bar coater (Eto Kikai)
And dried at room temperature to form test specimens.
Was. The total coating amount of the entire coating film is about 24 g / m
^Two The total coating thickness of the entire coating after drying is about 40 μm.
Was.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.038 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 51 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured. As a result, the transmittance was as high as 98.04%. When the transmittance of the silica-containing coating layer (mixed coating layer) in the case of a coating thickness of 50 μm was calculated from Equation (2) using the Beer rule, the transmittance was 96.75%.

Example 6 20 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 3 and an acrylic / urethane resin-based aqueous emulsion paint (Dainippon) Clear type paint manufactured by Ink Chemical Industry Co., Ltd., Boncoat HY-
364 g (solid content: 45% by mass) (silica: resin = 1: 1 in terms of solid content) was placed in a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount was about 18 g / m ^{2 in} terms of solids, and the thickness of the coated film after drying was about 30 μm. The appearance of the coating was opaque and dull.

Next, on the cured coating film, acrylic
Urethane resin-based water-based emulsion paint (Clear type paint manufactured by Dainippon Ink and Chemicals, Inc., trade name Boncoat HY
-364, solid content concentration 45% by mass) was applied using a # 20 bar coater (manufactured by Eto Kikai Co., Ltd.) and dried at room temperature to obtain a test piece. The total coating amount of the entire coating film was about 24 g / m ^{2 in} terms of solids, and the total coating thickness of the whole coating film after drying was about 40 μm. The appearance of the coating is transparent,
The coating film had high gloss.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.032 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
43 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured. As a result, the transmittance was as high as 98.75%. When the transmittance of the silica-containing coating layer (mixed coating layer) with a coating thickness of 50 μm was calculated from the equation (2) using the Beer rule, the transmittance was 97.93%.

Example 7 20 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass treated with a medium stirring bead mill described in Synthesis Example 4 and a urethane resin-based aqueous emulsion paint (Asahi Denka Kogyo Co., Ltd.) 10g (silica: resin = 1: 1 in terms of solids) of clear type paint, trade name Adekabon Titer HUX-350, solid content concentration 30% by mass) is put into a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition. Things.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount is about 18 g / m ^{2 in} terms of solids, and the thickness of the coating film after drying is about 30 μm
Met. The appearance of the coating was opaque and dull.

Next, a urethane resin-based water-based emulsion paint (clear type paint manufactured by Asahi Denka Kogyo KK, trade name: Adecabon Titer HUX-350,
A solid content concentration of 30% by mass) was applied using a # 20 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The total coating amount of the whole coating film is about 24 g on a solid basis.
/ M ² After drying, the total coating thickness of the entire coating was about 40 μm.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.035 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 47 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured. The transmittance was as high as 98.72%. Using the Beer's rule, the transmittance of the silica-containing coating layer (mixed coating layer) in the case of a coating thickness of 50 μm was calculated from Equation (2) to be 97.88%.

Example 8 24.4 g of a slurry (average particle size: 1.6 μm) having a solid content of 15% by mass, which was treated with the medium stirring bead mill described in Synthesis Example 3, was used as rutile-type ultrafine titanium oxide (Ishihara Techno Co., Ltd.). Company name, trade name TTO-5
0.1A of 1A average particle diameter 0.03 μm) and a urethane resin-based water-based emulsion paint (clear type paint manufactured by Asahi Denka Kogyo KK, trade name: Adecabon Titer HUX-3)
In a beaker, 7.4 g (solid content: 30% by mass) of silica: titanium oxide: resin = 61: 2: 37 in terms of solid content was put into a beaker, and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 100 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount was about 30 g / m ^{2 in} terms of solids, and the thickness of the coated film after drying was about 50 μm. The appearance of the coating was opaque and dull.

Next, an oily fluorine was applied on the cured coating film.
Resin-based emulsion paint (clear type paint manufactured by Asahi Glass Co., Ltd.)
Material, solvent xylene, trade name Lumiflon LF-200, solid
The form concentration is 60% by mass.
), And apply it at room temperature to form a test piece.
Was. The total coating amount of the entire coating film is about 6 g / m
^Two The total coating thickness of the entire coating after drying is about 55 μm.
Was.

When the pore volume of the cured coating film was measured by the BET method, the pore volume (corresponding to V ₁ in the formula (1)) was 0.030 ml / g. From this, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) (formula
V ₂ when obtaining the applicable) to V ₂ in (1), 0.0
It was 33 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured. The transmittance was 90.02%.

On the other hand, when the transmittance of light with respect to the ultraviolet light having a wavelength of 400 nm was measured, the transmittance was 8%.
The transmittance was 3.01%. Similarly, wavelength 360n
The light transmittance for light of m is 52.82%, wavelength 3
The light transmittance for light having a wavelength of 20 nm was 26.10%, and the transmittance for light having a wavelength of 290 nm was 18.54%.

Example 9 21.4 g of a slurry (average particle size: 0.54 μm) having a solid concentration of 14% by mass treated with a medium stirring bead mill described in Synthesis Example 5 and a urethane resin-based water-based emulsion paint (Asahi Clear type paint made by Denka Kogyo Co., Ltd., trade name Adecabon Titer HUX-35
10 g (silica: resin = 1: 1 in terms of solid content) was placed in a beaker, and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount is about 18 g / m ^{2 in} terms of solids, and the thickness of the coating film after drying is about 30 μm
Met.

When the pore volume of this cured coating film was measured by the BET method, the pore volume was 0.031 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured and found to be as high as 98.39%. When the transmittance of the silica-containing coating layer (mixed coating layer) with a coating thickness of 50 μm was calculated from the equation (2) using the Beer rule, the transmittance was 97.33%. The cured coating film was evaluated for pencil hardness and cross-cut peeling test in accordance with JIS K5400. The pencil hardness was H, and the cross-cut peel test was evaluated to be 10 points. The film-forming property was not impaired. It was confirmed that.

Example 10 21.4 g of a slurry (average particle size: 0.54 μm) having a solid content of 14% by mass treated with a medium stirring bead mill described in Synthesis Example 5 and an acrylic resin-based aqueous emulsion paint (large Clear type paint manufactured by Nippon Ink and Chemicals, Inc. Bon Coat BC-2
80, a solid content concentration of 50% by mass), 6 g (silica: resin = 1: 1 in terms of solid content) was placed in a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

In the same manner as in Example 9, the curable composition was applied to one surface of a quartz glass plate and dried at room temperature to obtain a test piece. The coating amount was about 18 g / m ^{2 in} terms of solids, and the coating thickness after drying was about 30 μm.

When the pore volume of the cured coating film was measured by the BET method, the pore volume was 0.030 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured and found to be as high as 98.45%. When the transmittance of the silica-containing coating layer (mixed coating layer) in the case of a coating thickness of 50 μm was calculated from Equation (2) using the Beer's rule, the transmittance was 97.43%.

The cured coating film was evaluated for pencil hardness and cross-cut peeling test according to JIS K5400. The pencil hardness was 2H and the cross-cut peel test was 10 points. It was confirmed that it was not.

Example 11 21.4 g of a slurry (average particle size: 0.54 μm) having a solid content of 14% by mass treated with a medium stirring bead mill described in Synthesis Example 5 and an acrylic resin-based water-based emulsion paint (large Clear type paint manufactured by Nippon Ink and Chemicals, Inc. Bon Coat BC-2
80, a solid content concentration of 50% by mass), 6 g (silica: resin = 1: 1 in terms of solid content) was placed in a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

In the same manner as in Example 9, the curable composition was applied to one surface of a quartz glass plate and dried at room temperature to obtain a test piece. The coating amount was about 18 g / m ^{2 in} terms of solids, and the coating thickness after drying was about 30 μm.

Next, an acrylic resin-based water-based emulsion paint (clear type paint manufactured by Dainippon Ink and Chemicals, trade name: Boncoat BC-280, solid content concentration: 50% by mass) was coated on the cured coating film with a # 20 bar. It was applied using a coater (manufactured by Eto Kikai Co., Ltd.) and dried at room temperature to obtain a test piece. The total coating amount of the entire coating film is about 24 g / m
^2. The total coating thickness after drying was about 40 μm.

When the pore volume of the cured coating film was measured by the BET method, the converted value of the pore volume of the silica-containing coating layer (mixed coating layer) was calculated as V ₂ in the formula (1). Found) was 0.028 ml / g. The appearance of the coating is
It was a transparent and highly glossy coating film.

Next, the light transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured and found to be as high as 98.88%. When the transmittance of the silica-containing coating layer (mixed coating layer) with a coating thickness of 50 μm was calculated from the equation (2) using the Beer rule, the transmittance was 98.14%. The cured coating film was evaluated for pencil hardness and cross-cut peeling test based on JIS K5400. The pencil hardness was 2H and the cross-cut peel test was 10 points. The film-forming property was not impaired. It was confirmed that.

[Comparative Example 1] 5 L of a silica tertiary aggregate slurry prepared by adding water to the wet cake after filtration and washing with the centrifuge shown in Synthesis Example 1 and adjusting the solid content to 14% by mass.
Using a medium agitation bead mill (Shinmaru Enterprises Co., Ltd., Dynomill KDL-PILOT A type)
(Vessel capacity 1.4L, 0.5mm diameter zirconia beads 70% filling)), shaft rotation speed 3400rpm,
The slurry was circulated at a flow rate of 10 L / h for 15 hours to obtain a ground water slurry having a solid concentration of 14% by mass.

A laser diffraction / scattering type particle size distribution measuring device for fine particles in the slurry after pulverization (manufactured by HORIBA, Ltd., LA-
920) was 0.49 μm.
Met. In addition, when the form of the silica particles was observed by SEM, it was found that the leaf-like silica secondary particles were almost completely pulverized to have a particle shape close to an irregular shape.

The slurry having a solid concentration of 14% by mass
1.4 g and urethane resin-based water-based emulsion paint (clear type paint manufactured by Asahi Denka Kogyo Co., Ltd., trade name: Adecabon Titer HUX-350, solid content concentration: 30% by mass) 1
0 g (silica: resin = 1: 1 in terms of solid content) was placed in a beaker and sufficiently stirred and mixed with a stirrer to obtain a curable composition.

Bar coater coating method (JIS K540)
In 0), the above curable composition was applied to one surface of a quartz glass plate using a # 80 bar coater (manufactured by Eto Kikai Co., Ltd.), and dried at room temperature to obtain a test piece. The coating amount is about 18 g / m ^{2 in} terms of solids, and the thickness of the coating film after drying is about 30 μm
Met.

When the pore volume of this cured coating film was measured by the BET method, the pore volume was 0.028 ml / g. The appearance of the coating film was transparent and had high gloss.

Next, the transmittance of the cured coating film formed on the quartz glass plate with respect to light having a wavelength of 500 nm was measured and found to be as high as 98.60%. Using the Beer's rule, the transmittance of the silica-containing coating layer (mixed coating layer) in the case of a coating thickness of 50 μm was calculated from Equation (2) to be 97.68%.

However, this cured coating film was subjected to JIS
When the pencil hardness and the cross-cut peeling test based on K5400 were evaluated, the pencil hardness was H. However, the cross-cut peeling test was evaluated as low as 2 points, and the adhesion between the substrate and the coating film was significantly reduced. It was confirmed that.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Atsushi Fujii, Inventor 13-1 Kitaminato-machi, Wakamatsu-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Inventor Eiichi Ono Kitaminato-cho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka No. 13-1 Dokai Chemical Industry Co., Ltd. (72) Inventor Takayoshi Sasaki No. 13-1 Dokai Chemical Industry Co., Ltd. 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka (72) Inventor Yoshimi Oba Wakamatsu, Kitakyushu-shi, Fukuoka 13-1 Kitaminatocho, Ward Dokai Chemical Industry Co., Ltd. F term (reference) 4J038 CC001 CD091 CG001 DB001 DG001 DL001 HA446 KA08 KA20 NA01 NA11 NA19 PC02 PC03 PC04 PC06 PC08

Claims (4)

[Claims] 1. A coating film comprising flaky silica secondary particles formed by laminating a plurality of flake primary particles of flaky silica with their planes being oriented parallel to each other and a transparent organic polymer substance. A wavelength 5 converted to a coating thickness of 50 μm of the coating film.
A substantially transparent cured coating film having a transmittance of light of 00 nm of 70% or more. 2. A coating film containing flaky silica secondary particles formed by laminating flaky silica flake primary particles and a plurality of superposed flake silica primary particles and a transparent organic polymer substance,
And a coating film comprising a top coat layer of a transparent organic polymer material, wherein the coating film has a wavelength of 50 μm in terms of a coating thickness of 50 μm.
A substantially transparent cured coating film having a transmittance of 0 nm light of 70% or more. 3. The cured coating film according to claim 1, wherein an average particle diameter of the foliar silica secondary particles is less than 1 μm. 4. The secondary foliar silica particles in the cured coating film are silica whose main peak in X-ray diffraction analysis corresponds to silica-X and / or silica-Y. The cured coating film according to the above.