JP2016224105A - Optical reflection film, optical component having the same, and method of manufacturing optical reflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical reflection film with a high area occupancy of reflective particles.SOLUTION: An optical reflection film comprises resin and reflective particles, and is characterized in that area occupancy of the reflective particles per unit area of 2×2 μm is 50% or more. Preferably, a number proportion of the resin present in gaps among the reflective particles present in the unit area of 2×2 μm is 90-100%, inclusive. An average diameter of the reflective particles is preferably no greater than 2 μm. Such an arrangement results in a film that is thin and yet exhibits superior reflection properties.SELECTED DRAWING: Figure 1

Description

  Embodiments to be described later relate to an optical reflection film, an optical component using the same, and a method for manufacturing the optical reflection film.

Optical reflective films are used in various fields as reflective films that mainly reflect visible light. Various uses such as a reflection film of a scintillator array and a reflection film of a substrate for mounting a light emitting element can be used as an application where an optical reflection film is used.
International Publication No. WO2013 / 080565 (Patent Document 1) discloses a mixture of TiO ₂ particles and resin in a reflective film of a scintillator array. Patent Document 1 of TiO ₂ particles and resin mixing step is carried out in a three-roll mixer. In such a system, when the amount of TiO ₂ (reflecting particles) added is increased, aggregates of TiO ₂ particles are formed, causing variations in reflection characteristics. For this reason, in patent document 1, the addition amount of reflective particles was not able to be increased.
In addition, International Publication No. WO2008 / 041382 (Patent Document 2) discloses an optical reflection film using an aggregate of nanoparticles (reflection particles). Since the nanoparticle aggregates are arranged on the resin layer, the reflective film as a whole was not a dispersion of the reflective particles uniformly.

International Publication Number WO2013 / 080565 International Publication Number WO2008 / 041382

  It has been difficult for conventional optical reflective films to contain many reflective particles in the resin layer. When the content of the reflective particles is increased, the aggregate becomes large or the aggregate increases. The reflectance of the optical reflection film is not only important for the physical properties of the reflective particles, but also the dispersion state of the reflective particles. It is necessary that the regions having different refractive indexes be uniformly present by uniformly dispersing the reflective particles and the resin in the optical reflective film. In the conventional optical reflection film, when the content of the reflective particles is increased, aggregates increase, so that regions having different refractive indexes cannot be formed uniformly. For this reason, there was a limit in improving the reflectance.

  The optical reflective film according to the embodiment is an optical reflective film made of resin and reflective particles, wherein the optical reflective film has an area occupancy of 50% or more of the reflective particles per unit area of 2 μm × 2 μm. . Since the dispersion state of the reflective particles per unit area can be made uniform, the reflectance can be improved.

The figure which shows an example of the optical reflection film concerning embodiment. The figure which shows an example of the dispersion state of the reflective particle of the optical reflection film concerning embodiment. The figure which shows another example of the optical reflection film concerning embodiment. The figure which shows an example of the scintillator array concerning embodiment. The figure which shows an example of the light emitting element mounting substrate concerning embodiment. The figure which shows an example of the manufacturing method of the optical reflection film concerning embodiment.

The optical reflective film according to the embodiment is an optical reflective film made of resin and reflective particles, wherein the optical reflective film has an area occupancy of 50% or more per unit area of 2 μm × 2 μm. .
FIG. 1 shows an example of the optical reflection film according to the embodiment. In the figure, 1 is an optical reflecting film, 2 is a reflecting particle, and 3 is a resin.
The optical reflective film according to the embodiment is obtained by dispersing the reflective particles 2 in the resin 3 film. Further, the area occupancy ratio of the reflecting particles per unit area 2 μm × 2 μm of the optical reflecting film is set to 50% or more. By increasing the area occupancy rate to 50% or more, the reflectance of the optical reflection film can be improved. Moreover, the optical reflection film can be thinned by increasing the proportion of the reflective particles.
In addition, the measuring method of the area occupation rate of reflective particles takes an enlarged photograph with a scanning electron microscope (SEM) in the arbitrary cross sections of an optical reflection film. The total area of the reflective particles per unit area 2 μm × 2 μm of the enlarged photograph is obtained. (Total area of reflective particles / 4 μm ² ) × 100 = Obtained area (%) of reflective particles.

Further, the upper limit of the area occupation ratio of the reflective particles is not particularly limited, but is preferably 85% or less. If the area occupation ratio of the reflective particles exceeds 85%, the ratio of the resin in the optical reflective film decreases. When the ratio of the resin decreases, the strength of the reflective film decreases. Further, when the area occupancy of the reflective particles is increased, the aggregates of the reflective particles are easily formed. Therefore, the area occupation ratio of the reflective particles is preferably 50 to 85%, more preferably 55 to 80%.
Moreover, it is preferable that the ratio of the resin existing in the gap between the reflective particles existing per unit area of 2 μm × 2 μm is 90% or more and 100% or less.
FIG. 2 shows an example of the dispersion state of the reflective particles. In the figure, 2 is a reflective particle, 3 is a resin, and 4 is an aggregate of reflective particles. Further, 4-1 is an aggregate composed of two reflective particles, and 4-2 is an aggregate composed of three reflective particles. Further, h is the gap between the reflective particles, W1 is the major axis of the aggregate 4-1, and W2 is the major axis of the aggregate 4-2.

The ratio of the resin existing in the gap between the reflective particles existing per unit area of 2 μm × 2 μm is 90% or more and 100% or less in terms of the number ratio, which means that the gap h between the reflective particles is present at a ratio of 90% or more. Indicates to do. By the presence of the resin in the gaps between the individual reflective particles, it is possible to create a region where the reflective particles and the resin are alternately present. When the reflective particles and the resin are alternately present, regions having different refractive indexes can be continuously present. In such a state, the reflectance is improved. When aggregates of reflective particles are present, regions having different refractive indexes cannot be continuously formed. Therefore, it is preferable that the ratio of the resin existing in the gap between the reflective particles is 90% or more and 100% or less in terms of the number ratio. It is most preferable that the ratio of the resin existing in the gap between the reflective particles is 100% in terms of the number ratio.
Moreover, the measuring method of the ratio that resin exists in the clearance gap between the reflective particles which exist per unit area 2micrometer x 2micrometer uses SEM photograph (enlarged photograph), and whether resin can be confirmed in the clearance gap between reflective particles. Check. The number of reflective particles present per unit area of 2 μm × 2 μm and the number of resin that can be confirmed in the gap are determined. Moreover, that resin can be confirmed in the clearance gap between reflective particles shows the state which presence of resin can be confirmed in the circumference | surroundings of one reflective particle in an enlarged photograph. Those in which the reflective particles are in direct contact like the aggregates 4-1 and 4-2 shown in FIG. 2 are counted as reflective particles in which no resin can be confirmed in the gap. Moreover, the aggregate which consists of two reflection particles like the aggregate 4-1 counts two reflective particles which cannot confirm resin in a clearance gap. Moreover, the aggregate which consists of three reflective particles like the aggregate 4-2 counts the reflective particle which resin cannot confirm in a clearance gap to three pieces. Similarly, for an aggregate composed of four or more reflective particles, the number of the reflective particles constituting the aggregate is counted, and the number of the reflective particles in which no resin can be confirmed in the gap is set. When it is difficult to confirm with an SEM photograph, a transmission electron microscope (TEM) may be used.

The average particle size of the reflective particles is preferably 1 μm or less. The average particle size of the reflective particles is preferably 0.5 μm or less, more preferably 0.1 μm or less. As described above, by forming a region where the reflective particles and the resin are alternately present, a region having a different refractive index can be formed with a minute region. This improves the reflectivity. When the particle diameter of the reflective particles becomes too large, it becomes impossible to make a region having a different refractive index a minute region.
The average particle size of the aggregate of reflective particles is preferably 2 μm or less. When the aggregate of the reflective particles is large, it is difficult to make a region having a different refractive index a fine region. Therefore, it is preferable that the aggregate of the reflective particles is small. Of course, it is most preferred that no aggregates be present. Therefore, the aggregate of the reflective particles preferably has an average particle size of 2 μm or less, more preferably 1.5 μm or less.

Moreover, the measuring method of the average particle diameter of the aggregate of reflective particles takes an SEM photograph (enlarged photograph) per unit area 2 μm × 2 μm. In the enlarged photograph, a region where the resin cannot be confirmed in the gap between the reflective particles is defined as an aggregate. The major axis of the aggregate is defined as the particle diameter of the aggregate. The average value of the particle size of the aggregate existing per unit area of 2 μm × 2 μm is defined as the average particle size of the aggregate. For example, in FIG. 2, the average value of W1 and W2 is the average particle size of the aggregate.
The average aspect ratio of the reflective particles is preferably 1.5 or more. FIG. 3 shows another example of the optical reflecting film according to the embodiment. In the figure, 1 is an optical reflecting film, 2 is a reflecting particle, and 3 is a resin.
When the average aspect ratio of the reflective particles is 1.5 or more, the triple point between the reflective particles can be reduced. As a result, the area occupation ratio of the reflective particles can be increased. The upper limit of the average aspect ratio of the reflective particles is not particularly limited. However, when the average aspect ratio is preferably 3.0 or less and larger than 3, it is difficult to make a region having a different refractive index a minute region. Become. Therefore, the average aspect ratio of the reflective particles is preferably in the range of 1.5 to 3.0.
Moreover, the method of calculating | requiring the aspect-ratio of reflective particle | grains observes the cross section of the thickness direction of the optical reflection film 1 with a SEM photograph (enlarged photograph). The maximum diameter of the reflective particles reflected per unit area 2 μm × 2 μm is defined as the major axis. The length that extends vertically from the midpoint of the major axis is the minor axis. The major axis / minor axis = aspect ratio. This operation is performed on all the reflective particles appearing in the area of 2 μm × 2 μm, and the average value is defined as the average aspect ratio.

Further, the gap h between the reflective particles is preferably 0.5 μm or less, and more preferably 0.2 μm or less. As shown in FIG. 2, the gap h between the reflective particles indicates the closest distance among the adjacent reflective particles. That is, when there are a plurality of reflective particles around one reflective particle, the distance to the closest reflective particle is defined as the gap h.
By reducing the gap h, the area occupation ratio of the reflective particles can be increased. The lower limit value of the gap h between the reflective particles is preferably 0.01 μm or more. The aggregate of the reflective particles has a gap h = 0 μm. The gap h is preferably set to 0.01 μm or more so that no aggregate is present.
The gap h between the reflective particles preferably has an average value of 0.1 μm or less. By setting the average value of the gap h to 0.1 μm or less, the area occupancy of the reflective particles can be increased. In addition, the average value of the gap h is obtained by measuring the gap h of the reflective particles reflected in a unit area of 5 μm × 5 μm and obtaining the average value.

The reflective particles are preferably one or more selected from titanium oxide, aluminum oxide, tantalum oxide, zirconium oxide, silicon oxide, and chromium oxide. It is preferred titanium oxide is TiO _2. The aluminum oxide is preferably Al ₂ O ₃ . The tantalum oxide is preferably Ta ₂ O ₅ . It is preferred zirconium oxide is ZrO _2. The silicon oxide is preferably SiO ₂ . The chromium oxide is preferably Cr ₂ O ₃ .
Among these, TiO ₂ and _Ta 2 _{O 5} is preferred. These two have high reflectivity of visible light (wavelength 400 to 750 nm). TiO ₂ has a high refractive index of 2.50. Further, it is preferred that TiO ₂ is rutile. TiO ₂ includes a rutile type, anatase type, brookite type, and the like. Of these, the rutile type has low photocatalytic properties. Therefore, there is little deterioration of the resin. As a result, deterioration of the optical reflection film can be prevented. Further, in order to suppress the photocatalytic properties of TiO ₂ , one or more second reflective particles selected from Al ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , SiO ₂ , Cr ₂ O ₃ are mixed. May be. When the total amount of the reflective particles is 100 parts by mass, TiO ₂ is preferably 70 to 98%, and the second reflective particles are preferably 30 to 2 parts by mass. Further, the one selected from _{Al 2 O 3, Ta 2 O} 5, ZrO 2, SiO 2, Cr 2 O 3 on the surface of the TiO ₂ particles may be used after coating.

The resin is not particularly limited as long as it is organic. Examples of the resin include one or more selected from epoxy resins, silicone resins, phenol resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethane resins, and polyimide resins. These resins can make the difference in refractive index from the reflective particles 0.20 or more.
In this, it is preferable that it is comprised from 1 type, or 2 or more types selected from silicone resin, epoxy resin, imide resin, and vinyl resin. These resins are easy to adjust the surface-coated reflective particles coated with a resin as described later. These resins have a refractive index of around 1.50. The refractive index of TiO2 is 2.50 to 2.72. The difference in refractive index between the resin and the reflective particles can be 0.20 or more, and further 0.80 or more. As described above, by making the dispersion state of the reflective particles and the resin uniform, it is possible to form regions having different refractive indexes as minute regions. As a result, the reflectance of the optical reflection film can be improved.

Moreover, it is preferable that the film thickness of an optical reflection film is 5-100 micrometers. When the film thickness t is less than 5 μm, the absolute value of the abundance of the reflective particles in the optical reflective film decreases. Therefore, there is a possibility that sufficient reflectance cannot be obtained. On the other hand, when the film thickness t exceeds 100 μm, it is difficult to obtain a further improvement in reflectance. The film thickness t of the optical reflection film is preferably 10 to 50 μm.
Such an optical reflection film can improve the reflectance. By using reflective particles selected from TiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , SiO ₂ , Cr ₂ O ₃ , the reflectance in the visible light region (wavelength 400 to 750 nm) can be improved. it can. In particular, the reflectance of light having a wavelength of 510 nm can be 94% or more, and the reflectance of light having a wavelength of 670 nm can be 91% or more.

The optical reflection film as described above is suitable for various optical components. In particular, it is suitable for an optical component that reflects visible light. Further, since the film thickness t can be made 100 μm or less, it is suitable for a product that requires a thin reflective film. Examples of such products include scintillator arrays, light-emitting element mounting substrates, and integrating spheres for measuring light flux. In other words, the optical component is preferably any one of a scintillator array, a light emitting element mounting substrate, and a light beam measuring integrating sphere.
FIG. 4 shows an example of the scintillator array. In the figure, 1 is an optical reflecting film, 5 is a scintillator array, and 6 is a scintillator. A scintillator array 5 is obtained by arranging and integrating the optical reflection film 1 in the gap between the scintillators 6. The scintillator array 5 is used in an X-ray detector using X-rays such as a CT (Computer Tomography) apparatus and a luggage inspection apparatus. The X-ray detector is converted into visible light when the X-ray hits the scintillator 6. This visible light is converted into an electrical signal by a detector such as a photodiode. By using the optical reflection film 1 according to the embodiment for the scintillator array 5, the reflectance is improved, so that the light output of the scintillator array 5 can be improved. In addition, since the area occupancy of the reflective particles in the optical reflection film is as high as 50% or more, the thickness t of the optical reflection film can be reduced. By reducing the thickness of the optical reflection film to 100 μm or less, the pitch of the scintillator 6 can be reduced. Thereby, a detection pixel can be reduced in size (high definition). In addition, since the area occupancy of the reflective particles in the optical reflection film is increased, the occurrence of crosstalk can be suppressed even if the thickness is reduced. As described above, the scintillator array according to the embodiment can improve the light output, increase the definition, and suppress the crosstalk by using the optical reflection film according to the embodiment as the reflection film.

  FIG. 5 shows an example of a light emitting element mounting substrate. In the figure, 1 is an optical reflecting film, 7 is a substrate for mounting a light emitting element, 8 is a substrate, and 9 is a light emitting element. Examples of the light emitting element 7 include a light emitting diode (LED) and a laser. A light emitting element 7 is mounted on the substrate 8. By providing the optical reflecting film 1 on the substrate 8, light from the light emitting element can be reflected. The light-emitting element mounting substrate 7 is a substrate in which the optical reflection film 1 is provided on the substrate 8. A device in which the light emitting element 9 is mounted on the light emitting element mounting substrate 7 is referred to as a light emitting device. Since the light emitting device using the light emitting element mounting substrate according to the embodiment can reflect the light from the light emitting element, the light emission efficiency can be improved. In particular, since the optical reflective film 1 according to the embodiment has a high visible light reflectance, it is suitable for a light emitting element mounting substrate on which a light emitting element that emits visible light is mounted. Note that the light-emitting element that emits visible light may be a combination of a light-emitting diode and a phosphor layer.

In addition to the scintillator array and the light emitting element mounting substrate, it is suitable for optical components that are required to reflect visible light. An example of such an optical component is an integrating sphere for measuring light flux. The integrating sphere for measuring light flux is a device that arranges a light emitting element at the center of a hollow sphere and measures its total light flux and chromaticity. It is used to measure the light emission characteristics of a light emitting element that emits visible light such as a white LED. By providing the optical reflection film according to the embodiment on the reflection film on the inner surface of the integrating sphere, the reflectivity increases, so that the measurement accuracy can be improved.
The optical component according to the embodiment has an excellent reflectance even if it is a thin film having a thickness of 100 μm or less. Therefore, it is suitable for an optical component that produces an effect due to being a thin reflective film.
Next, the manufacturing method of the optical reflective film concerning embodiment is demonstrated. As long as the optical reflective film according to the embodiment has the above-described configuration, the manufacturing method thereof is not particularly limited, but examples of the method for obtaining efficiently include the following.

The method for producing an optical reflective film according to the embodiment includes a step of preparing surface-coated reflective particles in which the surface of the reflective particles is resin-coated, and spraying the surface-coated reflective particles with an accelerated gas and depositing on the substrate. And a process.
First, a step of preparing surface-coated reflective particles in which the surface of the reflective particles is resin-coated is performed. The reflective particles preferably have an average particle size of 1 μm or less. The reflective particles are preferably one or more selected from titanium oxide, aluminum oxide, tantalum oxide, zirconium oxide, silicon oxide, and chromium oxide. Next, a resin dilution solvent is prepared by diluting the resin with a solvent. Regarding the solvent, a solvent capable of diluting a resin such as an organic solvent is used.

The reflective particles are mixed in the resin dilution solvent and sufficiently stirred. Thereafter, a method of spraying and drying a resin dilution solvent containing reflective particles by a spray drying method is preferable. There is also a method of coating the reflective particles by repeatedly spraying and drying a resin dilution solvent. Further, the resin dilution solvent containing the reflective particles is sufficiently mixed with a ball mill or the like. Remove the mixture and dry. A method of coating by repeating this mixing and drying may also be mentioned. A method of preparing surface-coated reflective particles in which the surface of the reflective particles is resin-coated using a resin dilution solvent containing such reflective particles is preferable. By using the resin dilution solvent, the surface of the reflective particles can be easily coated with the resin. Further, by forming the surface-coated reflective particles in advance, it is possible to prevent the aggregates of the reflective particles from being formed.
The thickness of the resin film is preferably 0.1 μm or less. By using a thin film of 0.1 μm or less, the area occupancy ratio of the reflective particles in the optical reflective film can be increased.
Further, it is preferable to granulate the surface-coated reflective particles to a certain size. By setting it as a granulated body (secondary particle), the injection efficiency in an injection process can be improved. The average particle size of the secondary particles is preferably 3 to 50 μm, more preferably 5 to 20 μm. Further, heat treatment to such an extent that the resin film does not disappear may be applied as necessary.

Next, an injection process is performed in which the surface-coated reflective particles are injected with an accelerated gas and deposited on the substrate. FIG. 6 shows an example of the injection process. In the figure, 10 is a surface-coated reflective particle, and 11 is a substrate.
The substrate is preferably a substrate for providing an optical reflective film. With this method, the base material provided with the optical reflection film can be used as an optical component as it is. Alternatively, the optical reflective film provided on the base material may be once peeled off and attached to the base material of the optical component. This case is effective when an optical reflection film is provided on a spherical surface like an integrating sphere for measuring light flux.
Moreover, it is preferable that the said injection process is a 1 type, or 2 or more types of mechanical deposition system selected from the cold spray method, the HVAF method, and the HVOF method. The mechanical deposition method can be sprayed without applying high heat to the surface-coated reflective particles. Therefore, it is possible to form a film without losing the resin on the surface of the reflective particles. For this reason, formation of the aggregate of reflective particles can be suppressed significantly.
Further, by increasing the jetting speed, it is possible to increase the stress at which the surface-coated reflective particles collide with the substrate. Thereby, the reflective particles can be plastically deformed to have a flat shape. If it is a plastic deformation in an injection process, it can be made flat in the direction parallel to the substrate.
In the injection step, the surface-coated reflective particles are accelerated by compressed gas (working gas) and injected toward the substrate. Here, examples of the working gas used include helium, argon, air, oxygen, nitrogen, and a mixed gas thereof. These gases are preferable because they do not react with the resin.
Moreover, it is preferable to perform injection at a high speed of 100 m / s or more, further 400 m / s or more as a particle speed. Moreover, it is preferable that it is a relatively low temperature that the said powder does not melt substantially by working gas temperature. The temperature of the working gas is preferably 280 ° C. or lower, more preferably 140 ° C. or lower. A resin that does not disappear at this temperature is also selected.

Examples of such spraying methods include a cold spray method, an HVAF method, and an HVOF method. In these methods, the temperature of the working gas can be substantially lowered by increasing the injection speed.
In general, the cold spray method is a method in which a gas having a temperature lower than the melting point or softening temperature of the raw material powder is converted to a supersonic flow, the raw material particles are injected into the flow, accelerated, and collided with the substrate in the solid state. It is. As the gas to be used, air may be used, but in general, it is preferable to use a non-oxidizing gas such as nitrogen, helium or argon in order to prevent oxidation.
The HVOF (High Velocity Oxygen Fuel) method and the HVAF (High Velocity Aero Fuel) method are a type of flame spraying method using a combustion flame. The former HVOF method uses high-pressure oxygen for fuel combustion, and the latter The HVAF method uses compressed air instead of the high-pressure oxygen. In general, both methods are methods in which the raw material powder is melted or softened by heating, accelerated into fine particles, and collided with the surface of the substrate.

Among the cold spray method, the HVAF method, and the HVOF method, the cold spray method is preferable. This is because the cold spray method suppresses the most heating of the surface-coated reflective particles. Therefore, since there is little thermal alteration, it becomes easy to obtain a favorable reflective film. This is particularly effective when surface-coated reflective particles having a thin film with a resin coating thickness of 0.1 μm or less are used.
In addition, when the HVOF method is adopted, the film formation rate is very high, which is suitable for mass production. Further, when the HVAF method is adopted, the combustion temperature can be suppressed lower than that of the HVOF method, and oxidation is suppressed because air is used. Further, the film forming cost can be made relatively low.
In addition, in order to control the injection speed, the injection nozzle inlet gas pressure, the injection nozzle inlet gas temperature, the distance between the injection nozzle and the substrate, the amount of powder supplied to the injection device, the moving speed of the nozzle or substrate, etc. What is necessary is just to select an optimal value according to the material of a powder, a particle size, etc. In addition, by forming a film using secondary particles of the surface-coated reflective particles, the amount of film formation can be increased, and the film formation efficiency can be improved.

(Example)
(Examples 1-5, Comparative Example 1)
A resin dilution solvent was prepared by diluting the resin with an organic solvent. Next, after adding the reflective particles and stirring sufficiently, surface-coated reflective particles in which the surfaces of the reflective particles were coated with a resin were prepared by spray drying. The results are shown in Table 1.
Moreover, as Comparative Example 1, TiO ₂ particles were added to an epoxy resin and mixed with three rolls. In Table 1, TiO ₂ was a rutile type. In Example 3, an Al ₂ O ₃ coating film having a thickness of 0.02 μm was provided. In Example 5, a TiO ₂ 90 parts by weight, in which the _Al 2 _{O 3} were mixed at a ratio of 10 parts by weight.

  Film formation was performed under the following film formation conditions. In Examples and Comparative Examples, a film was formed on a base material made of an Al plate (plate thickness: 4 mm). In Examples 1 to 5, the secondary particles shown in Table 1 were used. In Comparative Example 1, a film was formed by applying a mixture of reflective particles and resin.

(Cold spray method: CS method)
・ Nozzle inlet gas pressure: Helium gas 1MPa
・ Nozzle inlet gas temperature: 315 ° C
・ Nozzle-substrate distance: 10mm
・ Powder supply amount: about 10 g / min
・ Nozzle moving speed: 25 to 40 mm / s
-Substantially working gas temperature: 90-140 ° C

(HVAF method)
・ Nozzle inlet gas pressure: Air 0.6MPa
・ Nozzle inlet gas temperature: about 1200 ℃
・ Distance between nozzle and substrate: 200mm
・ Powder supply amount: about 150 g / min
・ Nozzle moving speed: 500 to 600 mm / s
-Substantially working gas temperature: 150-230 ° C

(HVOF method)
・ Nozzle inlet gas flow rate: Oxygen 5 gal / hr
・ Nozzle inlet gas temperature: about 1500 ℃
・ Distance between nozzle and substrate: 350mm
・ Powder supply amount: about 200 g / min
・ Nozzle moving speed: 1000 to 1100 mm / s
-Substantially working gas temperature: 180-270 ° C

About the obtained optical reflective film, the area occupancy of the reflective particles, the ratio of the resin in the gap between the reflective particles, the gap between the reflective particles, the average particle size of the aggregate of the reflective particles, the average aspect ratio of the reflective particles, Asked.
SEM photographs (enlarged photographs) were used for these measurements. A unit area of 2 μm × 2 μm is observed in the enlarged photograph. The magnification of the enlarged photograph is preferably 5000 times or more. The total area of the reflective particles is obtained from the enlarged photograph. The area ratio of the reflective particles was determined by (total area of reflective particles / 4 μm ² ) × 100 (%).
Further, using the same enlarged photograph (unit area 2 μm × 2 μm), the total number of the reflective particles and the number of the reflective particles in which the resin exists in the gap between the reflective particles are obtained. The ratio of the resin existing in the gap between the reflective particles was determined by (number of reflective particles in the gap between the reflective particles / total number of reflective particles) × 100 (%). Further, the gap h between the reflective particles indicates the closest distance among the adjacent reflective particles.
At that time, when the aggregate of the reflective particles was confirmed, the major axis of the aggregate was determined. The average value of the major axis was taken as the average particle size of the aggregate of reflective particles. Further, the major axis of the reflective particles shown in the enlarged photograph and the diameter extending perpendicularly to the midpoint of the major axis were defined as the minor axis. (A major axis / minor axis) was defined as an aspect ratio, and an average value of the aspect ratios of all the reflective particles reflected in a unit area of 2 μm × 2 μm was defined as an average aspect ratio.
The results are shown in Table 2.

As can be seen from the table, the optical reflection film according to the example had a high area occupation ratio of the reflective particles. In addition, there were few aggregates and the gaps between the reflective particles were small.
Next, the reflectance of visible light was calculated | required regarding the optical reflection film concerning an Example and a comparative example. The reflectance was measured by irradiating the optical reflective film with light having a wavelength of 510 nm or 670 nm to obtain the reflectance. The results are shown in Table 3.

  As can be seen from the table, the optical reflection film according to the example had excellent reflectance. As in Comparative Example 1, the reflectance is equal to or higher than that of a film having a thickness of 300 μm. For this reason, the optical reflection film can be made thin. This is because the state in which the resin is present in the gap between the reflective particles can be a minute region. This is because by using such a minute region, regions having different refractive indexes can be formed minutely and continuously.

Next, the scintillator array was produced using the optical reflection film concerning an Example and a comparative example. The light output of each scintillator array and the presence or absence of crosstalk were measured. Moreover, the scintillator array used the scintillator of length 0.8mm * width 0.8m * thickness 1.0mm.

The light output of the scintillator array is shown as a ratio when the light output of Comparative Example 1A is 100. Crosstalk is defined by the ratio of the output in the incident cell and the output in the adjacent cell when X-rays are incident on a specific cell separated by the reflective film.
The results are shown in Table 4.

  As can be seen from the table, the light output of the scintillator array according to the example was improved. Also, crosstalk was suppressed. In addition, since the thickness of the reflective film can be reduced, the pitch between the scintillators can be reduced. Therefore, high definition can be achieved.

  As mentioned above, although several embodiment of this invention was illustrated, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, changes, and the like can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

DESCRIPTION OF SYMBOLS 1 ... Optical reflective film 2 ... Reflective particle 3 ... Resin 4, 4-1, 4-2 ... Reflective particle aggregate 5 ... Scintillator array 6 ... Scintillator 7 ... Light emitting element mounting substrate 8 ... Substrate 9 ... Light emitting element 10 ... Surface-coated reflective particles 11 ... base material

Claims (15)

An optical reflective film comprising a resin and reflective particles, wherein the optical reflective film has an area occupancy of 50% or more per unit area of 2 μm × 2 μm.   2. The optical reflecting film according to claim 1, wherein the ratio of the resin existing in the gap between the reflecting particles existing per unit area of 2 [mu] m * 2 [mu] m is 90% or more and 100% or less.   The optical reflective film according to claim 1, wherein the average particle diameter of the reflective particles is 1 μm or less.   The optical reflective film according to any one of claims 1 to 3, wherein the average particle diameter of the aggregate of the reflective particles is 2 µm or less. The optical reflective film according to any one of claims 1 to 4, wherein the average aspect ratio of the reflective particles is 1.5 or more. 6. The reflective particle according to claim 1, wherein the reflective particle is one or more selected from titanium oxide, aluminum oxide, tantalum oxide, zirconium oxide, silicon oxide, and chromium oxide. The optical reflective film as described.
The optical reflective film according to claim 1, wherein the optical reflective film has a thickness of 5 to 100 μm. The said resin is comprised from 1 type, or 2 or more types selected from silicone resin, epoxy resin, imide resin, and vinyl resin, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The optical reflective film described in the seed. 9. The optical reflection film according to claim 1, wherein the reflectance of light having a wavelength of 510 nm is 94% or more and the reflectance of light having a wavelength of 670 nm is 91% or more. . An optical component comprising the optical reflecting film according to any one of claims 1 to 9. 11. The optical component according to claim 10, wherein the optical component is any one of a scintillator array, a light emitting element mounting substrate, and a light beam measuring integrating sphere. An optical reflection comprising: preparing a surface-coated reflective particle having a resin-coated surface of the reflective particle; and spraying the surface-coated reflective particle with an accelerated gas and depositing the surface-coated reflective particle on a substrate. A method for producing a membrane. 13. The method for producing an optical reflecting film according to claim 12, wherein the thickness of the resin coating is 0.1 [mu] m or less. The method for producing an optical reflecting film according to any one of claims 12 to 13, wherein the average particle diameter of the reflecting particles is 2 µm or less. The said injection | pouring process is 1 type, or 2 or more types of mechanical deposition systems selected from the cold spray method, the HVAF method, and the HVOF method, The any one of Claim 12 thru | or 14 characterized by the above-mentioned. The manufacturing method of the optical reflecting film as described in any one of.

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