JP2020097730A - Surface antireflection coating for atomization coating, and surface antireflection coated film - Google Patents

Abstract

To provide a surface antireflection coating for atomization coating which has high antireflection performance even when being thin and is also excellent in jet-blackness.SOLUTION: A surface antireflection coating for atomization coating contains a binder resin, a carbon black, a hydrophobically treated dry silica, roughening particles, a dye and a solvent, in which the roughening particles are polyamide-based resin particles having an average particle diameter of 10 μm or more and 20 μm, an amount of the polyamide-based resin particles to be added is 10 pts.mass or more and 44 pts.mass with respect to 100 pts.mass of the binder resin, and an amount of the dry silica to be added is 14 pts.mass or more with respect to 100 pts.mass of the binder resin.SELECTED DRAWING: None

Description

The present invention relates to a surface antireflection coating for atomization coating, and a surface antireflection coating film using the surface antireflection coating for atomization coating.

In optical devices such as digital cameras and digital video cameras, stray light due to diffuse reflection and scattering in the optical path part of the lens barrel and the like causes stray light in the formed image, which may be one of the causes of image quality deterioration. is there. Therefore, in order to suppress the deterioration of the optical performance due to such stray light, a black antireflection paint or an antireflection film is applied to the optical path portion such as the lens barrel and the diaphragm.

On the other hand, black anti-reflection paint and anti-reflection film are not limited to optical devices such as cameras, but also in display devices with light emission such as meters, in order to improve the visibility by anti-reflection of the peripheral part. It is being used.

In addition, due to its jet blackness of black antireflection paint, it is also attracting attention as a paint that improves design.

The antireflection coating for optical equipment includes a binder resin, black fine particles, and a matting agent having a coefficient of variation of 20% or more and an average particle diameter corresponding to 35% to 110% of the thickness of the light shielding film. There is an example of a light-shielding film that uses a coating liquid (Patent Document 1).

In the method of Patent Document 1, by using a matting agent having a coefficient of variation of 20% or more, a matting agent having different particle diameters from a large particle diameter to a small particle diameter is present, and light incident at any angle Is to absorb. However, depending on the selected matting agent or binder resin, the matting agent itself may be exposed on the surface. Particularly, when a matting agent having a large particle size is exposed on the surface, the antireflection performance may be deteriorated.

In Patent Document 2, the light-shielding particles include base particles and a plurality of second particles having an average particle diameter smaller than the particle diameter of the base particles, and the plurality of second particles are An example of the light-shielding coating material for optical components arranged on the surface of the base particles is described.

The method of Patent Document 2 has a specular reflectance of the coating film of 0.3% even at a minimum value at an incident angle of 5 degrees, and cannot be said to be sufficiently applicable to an optical device having higher performance.

Further, Patent Document 3 describes a light-shielding film having a reduced glossiness by having an uneven shape having different macro and micro sizes.

The light-shielding film described in Patent Document 3 has a drawback that it cannot be applied to objects having various shapes such as paint. Further, it is difficult to control the uneven shape of the micro portion without using particles.

Japanese Patent No. 6096658 JP, 2017-57388, A JP, 2010-175653, A

An object of the present invention is to provide a surface antireflection coating for atomization coating and a surface antireflection coating which have high antireflection performance and excellent jet blackness.

The surface antireflection coating for atomization coating according to the present invention is a surface antireflection coating for atomization coating applied by atomization coating, which is a binder resin, carbon black, hydrophobized dry silica, and roughening particles. Containing a dye and a solvent, the roughening particles are polyamide resin particles having an average particle diameter of 10 μm or more and 20 μm or less, and the addition amount of the polyamide resin particles is 10 parts by mass with respect to 100 parts by mass of the binder resin. In the surface antireflection coating for atomization coating, the amount of the hydrophobic silica-treated dry silica is 14 parts by mass or more with respect to 100 parts by mass of the binder resin. is there.

According to the present invention, it is possible to provide a surface antireflection coating for atomization coating and a surface antireflection coating having high antireflection performance and excellent jet blackness.

Hereinafter, modes for carrying out the present invention will be described. Hereinafter, the surface antireflection coating for atomization coating may be simply referred to as “paint” and the surface antireflection coating may simply be referred to as “coating”.

The surface antireflection paint for atomization coating according to the present invention is a coating material applied by atomization coating. As a general coating method of a coating material, there is a method of coating without atomization with a brush, a roll coater, an applicator or the like, and these methods are called bulk coating. In bulk coating, since the paint does not form particles, the effect of forming irregularities on the surface of the coating film is small. Therefore, high antireflection performance cannot be obtained. On the other hand, in atomization coating, since the coating material is in the form of particles and is applied to the application target, it is considered that the effect of forming irregularities on the surface of the coating film is high and the antireflection performance is excellent.
As a method of atomizing coating, a method generally used for atomizing a coating material can be used, for example, an air spray method of atomizing with air and an airless method of applying pressure to atomize a liquid. A spray method can be mentioned.

The surface antireflection coating for atomization coating according to the present invention contains a binder resin, carbon black, hydrophobized dry silica, roughening particles, a dye and a solvent.

In this embodiment, the binder resin is not particularly limited. Resins such as acrylic resin, urethane resin, epoxy resin, alkyd resin, and polyester resin can be used. These binder resins may be used alone or in combination of two or more. Above all, an acrylic resin, which does not require cross-linking and can be formed into a coating film only by drying the solvent after coating on the substrate, can be preferably used.

Further, although carbon black is used as the black colorant, the type thereof is not particularly limited. It is possible to select carbon black having characteristics according to the desired blackness or jet blackness. From the viewpoint of blackness or jet blackness, a coloring carbon black having a nitrogen adsorption specific surface area of 100 m ² /g or more and a volatile content of 3.0% or more is preferable.

The amount of carbon black added is not particularly limited, but is preferably 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. When the amount is 5 parts by mass or more, the variation in the addition amount is small and stable black color can be controlled, and when the amount is 30 parts by mass or less, the viscosity of the coating material does not increase excessively and the coating property can be kept good.

The hydrophobized dry silica is used as a matting agent. Compared with untreated silica that has not been subjected to a hydrophobizing treatment and wet silica, dry silica is capable of forming small irregularities on large irregularities due to roughening particles, and is excellent in antireflection performance. Further, the dry silica has a larger specific surface area than the wet silica, which has less irregularities on the surface of the secondary aggregate due to its manufacturing method. Along with this, the specific surface area of the film becomes large, and the scattering of incident light becomes large. Therefore, it is considered that the surface antireflection property and the blackness are excellent.

The addition amount of the hydrophobized dry silica is 14 parts by mass or more based on 100 parts by mass of the binder resin. When the addition amount is 14 parts by mass or more, most of the hydrophobized dry silica is not buried in the binder resin in the coating film, and the matte performance is exhibited. From the viewpoint of matteness, antireflection property and jet blackness, the larger the amount of silica, the better the performance of the coating film. The addition amount of the hydrophobized dry silica is preferably 14 parts by mass or more and 19 parts by mass or less with respect to 100 parts by mass of the binder resin. When the addition amount of the hydrophobized dry silica is 19 parts by mass or less, the viscosity of the coating does not become too high, and the dispersion is sufficiently dispersed during the production of the coating. Further, when dispersed, the paint viscosity is sufficiently low, the coatability is good, and the coating film is less likely to become uneven.

The roughened particles are polyamide resin particles having an average particle size of 10 μm or more and 20 μm or less. The type of polyamide is not particularly limited to 6 nylon, 66 nylon, 12 nylon and the like. Generally, the surface of the roughening particles of the resin is smooth, but by using the polyamide resin particles, the binder resin and the hydrophobized dry silica as a matting agent are evenly present on the polyamide resin particles. Becomes As a result, it is possible to form a coating film having a uniform and fine uneven shape. When roughening particles of other materials such as acrylic resin particles or polyurethane resin particles are used, the roughening particles are deposited on the coating film, and the smooth surface of the roughening particles is exposed, resulting in surface reflectance. Will rise. The use of polyamide resin particles is preferable because the above problems do not occur.

The average particle diameter of the roughening particles is 10 μm or more and 20 μm or less. When the average particle diameter of the roughening particles is 10 μm or more, the effect of forming irregularities as the roughening particles is high, and the antireflection performance is sufficiently obtained. If the average particle size of the roughening particles is 20 μm or less, the diffuse reflectance can be suppressed. Further, as long as the average particle size is in the range of 10 μm or more and 20 μm or less, a plurality of roughening particles having different average particle sizes may be used at the same time.
The average particle size described here refers to a value obtained by measuring the particle size distribution by a laser diffraction scattering method and determining the number average particle size.

The addition amount of the polyamide resin particles is 10 parts by mass or more and 44 parts by mass or less with respect to 100 parts by mass of the binder resin. Further, it is more preferably 10 parts by mass or more and less than 24 parts by mass. When the addition amount of the polyamide resin particles is 10 parts by mass or more, the frequency of unevenness due to the roughening particles on the surface of the coating film is high and the antireflection performance is excellent. When the addition amount of the roughening particles is 44 parts by mass or less, the roughening particles do not become too dense and there is no possibility of falling off from the coating film. Further, if the addition amount of the roughening particles is less than 24 parts by mass, it is easy to control the thickness of the coating film during atomization coating, and the variation in the film thickness in the coating film produced under the same conditions is reduced, The stability of the quality of the coating film obtained can be made higher.

In the present invention, the paint contains a dye.
As described above, atomization coating has the advantage that the effect of forming irregularities on the surface of the coating film is high because the coating material becomes particulate and is applied to the application target. Compared with coating, it has a drawback of high light transmittance.
In the present invention, since the coating material contains a dye in addition to the roughening particles, the dye prevents the transmission of light and can suppress the influence of the light transmission in atomization coating.

The type of dye is not limited as long as it can maintain the jet blackness and antireflection property of the coating film. A dye having a wavelength absorption characteristic according to a desired absorption wavelength can be arbitrarily selected and used. The dye is preferably a black dye.

As the dye, one kind may be used, or a plurality of kinds of dyes such as a red dye, a yellow dye and a blue dye may be used in combination and the absorption wavelength may be adjusted and used.
The types of dyes include, for example, azo dyes, metal complex salt dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinone imine dyes, xanthene dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes. , Phthalocyanine dyes and metal phthalocyanine dyes.

Examples of dyes added for the purpose of absorbing light in the visible wavelength range include, for example, disazo dyes such as Solvent Black 3 (OIL BLACK HBB (manufactured by Orient Chemical Industry Co., Ltd.)) and Solvent Black 7 (NUBIAN BLACK). Examples thereof include nigrosine dyes such as TN-870 (manufactured by Orient Chemical Co., Ltd.). In particular, it is preferable to use Solvent Black 3 having a wide absorption wavelength in the visible light region as the dye that absorbs light in the visible region.

Examples of dyes added for the purpose of absorbing light having a wavelength in the near infrared region include naphthalocyanine dyes and dyes such as squarylium, diimmonium, diothylene and cyanine.

The addition amount of the dye is preferably 7 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the binder resin. If the added amount is 7 parts by mass or more with respect to 100 parts by mass of the binder resin, the effect of absorbing light as a dye can be highly obtained. The effect of the decrease of is reduced.

The solvent is preferably an organic solvent. The paint may be prepared by diluting the binder resin, hydrophobized dry silica, roughening particles and the like with the organic solvent. The organic solvent can be used without particular limitation as long as the binder resin is dissolved and the hydrophobized dry silica, roughening particles and the like can be dispersed. Examples thereof include toluene, ethyl acetate, butyl acetate, n-butanol and the like. The dilution rate can also be adjusted arbitrarily according to the application. Further, a plurality of solvents may be mixed and used in order to control the drying speed from the coating conditions. The drying speed can be controlled by mixing a plurality of solvents.

It is possible to add other additives to the paint within a range that maintains its antireflection performance. For example, a dispersant, a fungicide, etc. may be mentioned. Examples of the dispersant include a polymer comb dispersant, such as SOLSPERSE 24000GR (manufactured by Nippon Lubrizol Co., Ltd.).

Binder resin, carbon black, roughening particles, hydrophobized dry silica, and the like are dispersed in the solvent of the coating material, and an ordinary dispersion method can be used. For example, a ball mill, a paint shaker, a basket mill, a dyno mill, an ultra visco mill, an annular disperser, or the like can be used.

The surface anti-reflection coating film according to the present invention is a surface anti-reflection coating film formed by using the above-mentioned surface anti-reflection coating material for atomization coating, and has an incident angle of 20 degrees and an incident angle in the visible light range (360 nm to 740 nm). The average regular reflectance at an angle of 80 degrees is 0.5% or less, the average regular reflectance at an incident angle of 20 degrees in the near infrared region (850 nm to 2000 nm) and the incident angle of 80 degrees is 3.0% or less, the visible light range. A surface antireflection coating film having a diffuse reflectance of (360 nm to 740 nm) of 2.3% or less.

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

The raw materials used in each Example and Comparative Example are as shown below.
Acrylic resin: Acridic A-166 (manufactured by DIC Corporation)
Carbon black: RAVEN 5000UII (manufactured by Columbian Chemical Company)
Hydrophobized dry silica: ACEMATT 3300 (manufactured by Evonik Japan Ltd.)
Untreated dry silica: ACEMATT TS100 (Evonik Japan Co., Ltd.)
Hydrophobized wet silica: ACEMATT OK412 (manufactured by Evonik Japan Ltd.)
Coarse particles (5 μm) PA: Polyamide resin particles (average particle size 5 μm), SP-500 (manufactured by Toray Industries, Inc.)
Coarse particles (10 μm) PA: Polyamide-based resin particles (average particle size 10 μm), SP-10 (manufactured by Toray Industries, Inc.)
Coarse particles (15 μm) PA: Polyamide resin particles (average particle diameter 15 μm), TR-1 (manufactured by Toray Industries, Inc.)
Coarse particles (20 μm) PA: Polyamide resin particles (average particle size 20 μm), TR-2 (manufactured by Toray Industries, Inc.)
Coarse particles (50 μm) PA: Polyamide-based resin particles (average particle size 50 μm), Best Gint 2157 (manufactured by Daicel-Evonik Ltd.)
Roughened particles (15 μm) PMMA: Polymethylmethacrylate (PMMA) resin particles (average particle size 15 μm), Techpolymer MBX-15 (manufactured by Sekisui Plastics Co., Ltd.)
Coarse particles (15 μm) PU: Polyurethane particles (average particle diameter 15 μm), Art Pearl C-400 transparent (manufactured by Negami Kogyo Co., Ltd.)
Dye: OIL BLACK HBB (manufactured by Orient Chemical Industry Co., Ltd.)
Organic solvent: Butyl acetate (Kishida Chemical Co., Ltd.)

(Example 1)
Ratio of 22 parts by mass of carbon black, 14 parts by mass of dry-processed dry silica, 17 parts by mass of polyamide resin particles having an average particle diameter of 15 μm, 10 parts by mass of dye, and 133 parts by mass of organic solvent with respect to 100 parts by mass of acrylic resin. And mixed to prepare a paint mixture. The coating liquid mixture was adjusted so that the total amount was 200 g. Next, using a ball mill having a capacity of 500 ml, 20 balls of φ15 mm and 20 balls of φ10 mm (total 112 g) were charged and dispersed at 90 rpm for 5 hours to produce a coating material. The obtained paint was diluted with an organic solvent so that the viscosity was 20 to 30 mPa·s, and was used as a paint for coating. Using the obtained coating material for coating, RG-3L (manufactured by Anest Iwata Co., Ltd.) was used as a coating machine, and three reciprocating coating materials were applied on a PET film at a distance of 30 cm, an atomization pressure of 0.2 MPa and a speed of 15 cm/sec. Sprayed. The coating material sprayed on the PET film was dried at room temperature for 5 minutes and further dried at 70 degrees for 20 minutes to prepare a coating film.

(Examples 2-15, Comparative Examples 1-7, 10)
A coating material was prepared in the same manner as in Example 1 except that the types and amounts of silica and roughening particles and the amount of dye used in the preparation of the coating material were changed as shown in Tables 1 to 3. A coating film was prepared using the obtained coating material in the same manner as in Example 1.

(Comparative Example 8)
No dye was used in the preparation of the coating mixture in Example 1. A coating material was prepared in the same manner as in Example 1 except for the above. A coating film was prepared using the obtained coating material in the same manner as in Example 1.

(Comparative Example 9)
In Example 1, instead of atomizing coating, coating was performed by bulk coating to form a coating film. Specifically, the coating material obtained by stirring the coating liquid mixture is applied onto a PET film using an applicator with a gap of 100 μm, dried at room temperature for 5 minutes, and further dried at 70 degrees for 20 minutes. Then, a coating film was prepared.

(Measurement of regular reflectance)
The regular reflectance was measured as an evaluation of the surface antireflection performance. The regular reflectance is measured by using a spectrophotometer (V-670 manufactured by JASCO Corporation) equipped with an absolute reflectance measuring unit for the coating film obtained on the PET film as described above. It was The measurement conditions were such that the specular reflectance (absolute reflectance) was measured in the wavelength range of 350 nm to 2000 nm in steps of 1 nm at an incident angle of 20 degrees and an incident angle of 80 degrees. The specular reflectance in the visible light region was calculated by averaging the measured values obtained at wavelengths of 360 nm to 740 nm, and the specular reflectance in the near infrared region was calculated by averaging the measured values obtained at wavelengths of 850 nm to 2000 nm. The measurement results are shown in Tables 1 to 3.

(Diffuse reflectance measurement)
The diffuse reflectance was measured to evaluate the blackness and jetness of the surface. The diffuse reflectance was measured using a spectrophotometer (V-670 manufactured by JASCO Corporation) with a 150 mmφ integrating sphere unit attached to the coating film obtained on the PET film as described above. The specular reflection light was removed under the condition that the wavelength was 350 nm to 800 nm in steps of 1 nm, and the diffuse reflectance of only the diffuse reflection component was measured. The average value of the measured values obtained at wavelengths of 360 nm to 740 nm was calculated and used as the diffuse reflectance. The measurement results are shown in Tables 1 to 3.

(Liquid viscosity measurement)
The liquid viscosity of the coating material prepared above (the coating material before being diluted with an organic solvent for coating) was measured. For the measurement of the liquid viscosity, a B-type viscometer was used, and the viscosity was measured by a viscosity measuring device (Vismetron VSA-1 manufactured by Shibaura System Co., Ltd.) under the following conditions. Liquid temperature is 25°C, No. Two rotors were used, and the rotation speed was 12 rpm in the viscosity range of 25 cPs to 2500 cPs, and 6 rpm in the case of exceeding the viscosity range of 2500 cPs.

(Film thickness measurement and film thickness variation measurement)
The film thickness was measured by observing the cross section with an SEM (scanning electron microscope). Specifically, the cross section of the coating film on the PET film was observed at 1000 times, and within the observation range, the height from the PET film was 5 points from the highest point and 5 points from the lowest point. The measured value was averaged to obtain the film thickness. The measurement results are shown in Tables 1 to 3.
Further, five coating films prepared under the same conditions were prepared for each of the examples and comparative examples, and the film thickness was measured according to the above for each. After that, among the five film thickness values obtained from the five coating films, the difference between the maximum value and the minimum value was calculated and evaluated as the variation in the film thickness. The measurement results are shown in Tables 1 to 3.

(Evaluation)
From the measurement results of the film thickness, regular reflectance and diffuse reflectance, evaluation was performed as follows.
Specular reflectance at visible angles of 20° and 80° is 0.5% or less, regular reflectance at near infrared light of 20° and 80° is 3.0% or less, and diffuse reflectance of visible light Is A at the same time satisfying the condition of 2.3% or less. If even one of the conditions of A is not satisfied, it is B.

From Example 1, Comparative Example 5, and Comparative Example 6, it is understood that the roughening particles need to be polyamide resin particles. In both Comparative Example 5 using PMMA resin particles and Comparative Example 6 using polyurethane resin particles, the specular reflectance and diffuse reflectance at 80° of visible light and near infrared light were inferior.

From Examples 1, 3, 4 and Comparative Examples 3 and 4, it is understood that the grain size of the roughening particles needs to be 10 μm or more and 20 μm or less. Comparative Example 3 using roughened particles having a particle diameter of 5 μm and Comparative Example 4 using roughened particles having a particle diameter of 50 μm were inferior in diffuse reflectance of visible light.

From Example 1, Example 5, Example 6, and Comparative Example 7, it is understood that the addition amount of the roughening particles needs to be 10 parts by mass or more based on 100 parts by mass of the binder resin. In Comparative Example 7 in which the addition amount of the roughening particles was 5 parts by mass with respect to 100 parts by mass of the binder resin, the diffuse reflectance of visible light was inferior.
Further, from Examples 9 and 13 to 15, it is understood that the addition amount of the roughening particles is preferably 10 parts by mass or more and less than 24 parts by mass with respect to 100 parts by mass of the binder resin. In Examples 13 to 15 in which the addition amount of the roughening particles was 24 parts by mass or more with respect to 100 parts by mass of the binder resin, the variation in the film thickness was large.

From Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that it is necessary to use hydrophobized dry silica as the silica. Comparative Example 1 using untreated dry silica was inferior in the diffuse reflectance of visible light. Comparative Example 2 using the hydrophobized wet silica was inferior in the regular reflectance of near infrared light at 80 degrees and the diffuse reflectance of visible light.

From Example 1, Example 2, Example 7, and Comparative Example 10, the addition amount of the hydrophobized dry silica needs to be 14 parts by mass or more based on 100 parts by mass of the binder resin. It can be seen that it is preferably not less than 19 parts by mass. Comparative Example 10 in which the addition amount of the hydrophobized dry silica was 11 parts by mass was inferior in the diffuse reflectance of visible light.

It can be seen from Example 1 and Comparative Example 8 that the coating material needs to contain a dye. In Comparative Example 8 in which no dye was used, the diffuse reflectance of visible light was inferior.

From Example 1 and Comparative Example 9, it can be seen that the paint needs to be applied by atomization. In Comparative Example 9 in which the coating material was applied by bulk coating, the diffuse reflectance of visible light was inferior.

Claims (4)

A surface antireflection coating for atomization coating,
Contains binder resin, carbon black, hydrophobized dry silica, roughening particles, dye and solvent,
The roughened particles are polyamide resin particles having an average particle size of 10 μm or more and 20 μm or less,
The addition amount of the polyamide-based resin particles is 10 parts by mass or more and 44 parts by mass or less with respect to 100 parts by mass of the binder resin,
The surface antireflection coating for atomization coating, wherein the addition amount of the hydrophobized dry silica is 14 parts by mass or more with respect to 100 parts by mass of the binder resin. The surface antireflection coating for atomization coating according to claim 1, wherein the addition amount of the hydrophobized dry silica is 14 parts by mass or more and 19 parts by mass or less based on 100 parts by mass of the binder resin. The antireflection coating for atomization coating according to claim 1 or 2, wherein the amount of the polyamide resin particles added is 10 parts by mass or more and less than 24 parts by mass with respect to 100 parts by mass of the binder resin. A surface antireflection coating film formed by using the surface antireflection paint for atomization coating according to any one of claims 1 to 3, wherein an incident angle of 20 degrees in a visible light region (360 nm to 740 nm) and The average regular reflectance at an incident angle of 80 degrees is 0.5% or less, the average regular reflectance at an incident angle of 20 degrees in the near infrared region (850 nm to 2000 nm) and an incident angle of 80 degrees is 3.0% or less, A surface antireflection coating film having a diffuse reflectance of 2.3% or less in a visible light region (360 nm to 740 nm).