JP2004361924A - Coating type optical film material, and optical multilayer film and reflective screen using the same - Google Patents

Abstract

An object of the present invention is to provide a coating-type optical film material having a low surface tension that can freely select a refractive index in a wide range and can be applied even on a film having a low surface energy. Provided are an optical multilayer film and a reflective screen which have good transparency, are easy to mold, and are excellent in productivity.
Kind Code: A1 As a material for a coating type optical film, fine particles, an organic solvent, a binder which causes a curing reaction by absorbing energy, and a dispersant comprising a lipophilic group and a hydrophilic group having a chemical formula amount of 110 to 3000. And the content of the dispersant is 2.2 to 22 μmol / m ² with respect to the fine particles, and the surface tension when applied is 19 dyne / cm or less.
[Selection diagram] Fig. 1

Description

  The present invention relates to a material for a coating type optical film, and relates to an optical multilayer film formed using the material, and further to a reflection screen provided with the optical multilayer film.

  Optical materials include inorganic optical materials such as glass and organic polymer optical materials such as plastics, but all optical materials have some disadvantages and do not satisfy all the requirements required for optical materials. Was.

  That is, the organic polymer optical material is easy to mold into various shapes, has rapid mass productivity, has the advantage of being light and hard to crack, but has a low refractive index, is soft, is easily damaged, and has hygroscopicity. For this reason, there are disadvantages such as a change in optical properties due to a change in shape and a large birefringence.

  On the other hand, inorganic optical materials have the advantages of being hard and resistant to scratching, having high heat resistance, low hygroscopicity, being able to select a wider range of refractive indexes than organic polymer optical materials, having a low birefringence, and having high resolution. However, it had the disadvantages of being easily broken by impact, poor moldability, and poor rapid mass productivity.

Therefore, at present, both are insufficient as optical materials, and new optical materials satisfying the following five characteristics without those disadvantages have been demanded.
1) Good workability,
2) freely and continuously selectable refractive index values;
3) It has impact resistance and is hard to crack.
4) low colorability and high visible light transmittance in a wide wavelength range;
5) It is hard to be damaged

  Meanwhile, in examining the above optical materials, there is a method of providing a desired function as an optical material by laminating optical films having different refractive indexes on an optical film having a certain refractive index. For example, when a high refractive index film is provided below a low refractive index film having a refractive index of 1.35 to 1.45 for light having a wavelength of 550 nm, an effective antireflection film can be obtained (see, for example, Patent Document 1). ).

  In addition, it is possible to freely adjust the refractive index of the coating film by mixing fine particles of various metal oxides into the organic polymer material. , A method for improving the surface characteristics of a monitor and a lens, or using the same for an optical material has been proposed (for example, see Patent Document 2).

JP-A-11-64601 (paragraphs 0017 to 0018, FIG. 1) JP-A-2000-171603 (paragraph 0024, FIG. 1)

  However, when an organic polymer material to which the above-mentioned fine particles are added is applied on a fluorine-containing film or a release film to form an optical film, the surface tension of the organic polymer material is reduced to a fluorine-containing film or a release film. And the like, and could not be laminated because the surface energy was higher than the surface energy.

  The present invention has been made in view of the above-described problems in the prior art, and a coating type optical film having a low surface tension that can freely select a refractive index in a wide range and can be applied on a film having a low surface energy. It is an object of the present invention to provide an optical multilayer film and a reflective screen which have good transparency to light in a wide wavelength range, are easy to mold, and are excellent in productivity.

The material for a coating type optical film according to the invention of claim 1 provided to solve the above-mentioned problem is a material for a coating type optical film which forms an optical film by coating on a fluorine-containing substrate, wherein fine particles, An organic solvent, a binder that absorbs energy to cause a curing reaction, and a dispersant composed of a lipophilic group and a hydrophilic group having a chemical formula amount of 110 to 3000, wherein the content of the dispersant is in the fine particles. In contrast, the surface tension is 2.2 to 22 μmol / m ² , and the surface tension when applied is 19 dyne / cm or less.
According to a second aspect of the present invention, there is provided a material for a coating type optical film, wherein the hydrophilic group of the dispersant is a sulfonic acid group, a sulfonic acid group, or a phosphate group. Alternatively, it is a phosphate group.
According to a third aspect of the present invention, there is provided a material for a coating type optical film according to the first aspect of the present invention, wherein the content of the fine particles is 2 to 20% by weight, and the primary particle diameter is 100 nm. It is characterized by the following.
According to a fourth aspect of the present invention, there is provided a material for a coating type optical film provided to solve the above-mentioned problem, wherein the optical film obtained after coating has a refractive index of 1.7 to 2.1. It is characterized by the following.

  According to the first to fourth aspects of the present invention, a material for a coating type optical film having a low surface tension can be freely selected in a wide range of the refractive index. It becomes.

  An optical multilayer film according to a fifth aspect of the present invention, which is provided to solve the above problem, comprises an optical film obtained by applying the material for a coating type optical film according to any one of the first to fourth aspects, and a fluorine-containing film. And at least a film.

  According to the fifth aspect of the present invention, the optical film made of the material for the coating type optical film according to the present invention having the target refractive index and film thickness is laminated with the fluorine-containing film, so that it has high reflectivity to light in a specific wavelength band. It becomes possible to form a functional optical film having characteristics and having high transmission characteristics at least for light in a visible wavelength region other than these wavelength regions by coating.

  According to a sixth aspect of the present invention, there is provided a reflection screen provided with a substrate, a light absorption layer, an optical multilayer film according to the fifth aspect, and a light diffusion layer. It is characterized.

  According to the sixth aspect of the invention, it is possible to selectively reflect light that reflects light of a specific wavelength from the projector and transmits / absorbs incident light in other wavelength regions such as external light. Higher contrast can be achieved by lowering the level, and a high-contrast image can be displayed even in a bright room.

According to the first to fourth aspects of the present invention, coating can be performed on a film having a low surface energy, and a laminated structure can be obtained.
According to the invention of claim 5, a functional optical film having a high reflection characteristic with respect to light in a specific wavelength band and a high transmission characteristic with respect to light in a visible wavelength region other than at least these wavelength regions. Can be formed by coating.
According to the invention of claim 6, high contrast can be achieved by lowering the black level of the image on the reflection screen, and an image with high contrast can be displayed even in a bright room.

  Hereinafter, embodiments of the coating type optical film material according to the present invention will be described. The embodiment described below is an example, and the present invention is not limited to this.

(Coating type optical film material)
The material for a coating type optical film according to the present invention is a material that forms an optical film by being coated on a fluorine-containing film, and is used for an optical film in which fine particles are dispersed by a dispersant in an organic solvent in which a binder is dissolved. Material. The material for the optical film is to be a high refractive index optical film by a curing reaction after being applied.

The material for a coating type optical film of the present invention comprises a fine particle, an organic solvent, a binder that causes a curing reaction by absorbing energy, and a dispersant comprising a lipophilic group and a hydrophilic group having a chemical formula amount of 110 to 3000. And the content of the dispersant is 2.2 to 22 μmol / m ² with respect to the fine particles, the surface tension when applied becomes 19 dyne / cm or less, and the optical film is formed by applying on a fluorine-containing substrate. Is a coating type optical film material. Further, the fluorine-containing substrate as the substrate can be applied to substrates and optical thin films of all shapes such as films, plates, and lenses.

  Fine particles of the material for the coating type optical film are fine particles of a high refractive index material added to adjust the refractive index of the optical film after being formed, and Ti, Zr, Al, Ce, Sn, La, Oxides such as In, Y, and Sb, and alloy oxides such as In—Sn are included. It should be noted that even if an appropriate amount of an oxide such as Al or Zr is contained in the Ti oxide for the purpose of suppressing the photocatalyst, the effect of the present invention is not hindered.

The specific surface area of the fine particles is preferably from 55 to 85 m ² / g, it is more preferably 75~85 m ² / g. When the specific surface area is in this range, the particle size (primary particle size) of the fine particles in the optical film material can be suppressed to 100 nm or less by the dispersion treatment of the fine particles, and an optical film having a very small haze can be obtained. It is possible.

  The content of the fine particles is preferably 2 to 20% by weight in the optical film material.

  Organic solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, propanol, butanol, and isobutyl alcohol; methyl acetate, ethyl acetate, butyl acetate, propyl acetate, and ethyl lactate. And an ester solvent such as ethylene glycol acetate. These organic solvents need not necessarily be 100% pure, and may be contained as long as impurities, such as isomers, unreacted materials, decomposed products, oxides, and moisture, are 20% or less. In addition, in order to coat on a support or an optical film having a low surface energy, it is desirable to select a solvent having a lower surface tension, and examples thereof include methyl isobutyl ketone, methanol, and ethanol.

  Examples of the binder include a thermosetting resin, an ultraviolet (UV) curable resin, and an electron beam (EB) curable resin. Examples of thermosetting resin, UV-curable resin, and EB-curable resin include polystyrene resin, styrene copolymer, polycarbonate, phenol resin, epoxy resin, polyester resin, polyurethane resin, urea resin, melamine resin, polyamine resin, and urea. Formaldehyde resin and the like can be mentioned. Polymers having other cyclic (aromatic, heterocyclic, alicyclic, etc.) groups may be used. Further, a resin containing a fluorine or silanol group in the carbon chain may be used.

  The method of causing the resin to undergo a curing reaction may be either radiation or heating. However, when the curing reaction of the binder is performed by irradiation with ultraviolet light, it is preferable to perform the reaction in the presence of a polymerization initiator. Examples of the radical polymerization initiator include azo initiators such as 2,2'-azobisisobutyronitrile and 2,2'-azobis (2,4-dimethylvaleronitrile); benzoyl peroxide, lauryl peroxide And a peroxide-based initiator such as t-butyl peroctoate. The amount of these initiators used is 0.2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the total of polymerizable monomers.

  The content of the binder is preferably 3 to 32 wt% in the optical film material.

  The dispersant improves the dispersibility of the fine particles and takes the form in which the dispersant oriented on the surface of the fine particles by the dispersion is also oriented on the surface of the material for the optical film. Suitable for lowering. The dispersant comprises a lipophilic group and a hydrophilic group, and the site of introduction of the polar functional group, which is a hydrophilic group, is not particularly limited.

  The weight average molecular weight (chemical formula weight) of the lipophilic group contained in the dispersant is 110 to 3000. When the molecular weight is lower than 110, adverse effects such as insufficient dissolution in an organic solvent occur, and when the molecular weight exceeds 3,000, sufficient dispersibility of the fine particles in the optical film cannot be obtained. The dispersant may have a functional group for causing a curing reaction with the binder.

The amount of the polar functional group of the hydrophilic group contained in the dispersant is 10 ^-3 to 10 ^-1 mol / g. If the number of functional groups is smaller or larger than this, the effect on dispersion of the fine particles is not exhibited, leading to a decrease in dispersibility. In addition, the following functional groups as polar functional groups are useful because they do not aggregate. That is, -SO ₃ M, -OSO ₃ M, -COOM, P = O (OM) ₂ (where M is a hydrogen atom or an alkali metal such as lithium, potassium, and sodium), 3 Quaternary amines, quaternary ammonium salts (R ₁ (R ₂ ) (R ₃ ) NHX (wherein R ₁ , R ₂ , R ₃ are hydrogen atoms or hydrocarbon groups, and X ^- is chlorine, bromine , Iodine and other halogen element ions or inorganic and organic ions.)), -OH, -SH, -CN, and polar functional groups such as epoxy groups. These dispersants can be used alone or in combination of two or more.

The content of the dispersant is 2.2 to 22 μmol / m ^{2 based on the} fine particles. If the content is less than 2.2 μmol / m ² , sufficient dispersibility cannot be obtained in the optical film, and a more effective surface tension lowering effect cannot be obtained. Conversely, if the content is more than 22 μmol / m ^{2, the} surface tension is reduced irrespective of the dispersion state of the fine particles, but the volume ratio of the dispersant in the optical film is increased. Since the adjustment range of the ratio becomes narrow, it becomes difficult to design an optical film stack. The molecular weight of the dispersant may be measured by gel permeation chromatography (GPC).
Further, the content of the dispersant in the coating film of the optical film material A is 20 to 60 parts by weight, more preferably 38 to 55 parts by weight, based on 100 parts by weight of the fine particles. When a binder other than the dispersant of the present invention is contained, a polyfunctional polymer or monomer having a large number of binding groups is preferred.

  The coating type optical film material has a surface tension of 19 dyne / cm or less when applied, and can be uniformly applied on a film having a low surface energy such as a fluorine-containing film. After being applied, the curing reaction is promoted by light or thermal energy, and a high refractive index type optical film is obtained.

  The production of the optical film material is performed by a kneading step, a dispersing step, and a mixing step provided before and after these steps as necessary. All raw materials such as fine particles, resin, and solvent used in the present invention may be added at the beginning or during any step. Further, the individual raw materials may be added in two or more steps in a divided manner. Conventionally known devices such as an agitator and a paint shaker may be used for dispersion and kneading.

(Optical multilayer film)
The optical multilayer film is the basis of the present invention. The optical film (I) having a high refractive index obtained by applying and curing the material for a coating type optical film as a first optical film, and a second optical film. The optical film has a structure in which low-refractive-index optical films (II), which are fluorine-containing films, are alternately laminated. More specifically, an optical film (I) is provided from the top of the substrate, then an optical film (II) is provided, and thereafter, the optical film (I) and the optical film (II) are provided alternately, and finally, the optical film (II) is provided. (I) is provided, and is a laminated film composed of 2n + 1 layers (n is an integer of 1 or more).

The optical film (I) is an optical film formed by applying a coating type optical film material on a substrate or an optical film (II) and then performing a curing reaction.
The thickness of this optical film is 80 nm to 15 μm, and more preferably 600 to 1000 nm. If the thickness is more than 15 μm, the haze component due to fine particles that cannot be completely dispersed increases, and the function as an optical film cannot be obtained.
The refractive index of the optical film is preferably set to 1.70 to 2.10. When the refractive index is higher than 2.10, the dispersibility of the fine particles becomes insufficient, and the function as an optical film is impaired. When the refractive index is lower than 1.70, required optical characteristics are obtained. May not be possible.

The optical film (II) is a fluorine-containing film formed by applying a predetermined base layer paint on the optical film (I) and then performing a curing reaction. The refractive index is preferably from 1.30 to 1.69, and a film having a refractive index of 1.45 or less is particularly preferable. The refractive index of the optical film (II) is determined by the type of resin contained in the paint, and in some cases, the type and amount of fine particles added. If the refractive index is higher than 1.69, a difference in the refractive index from the optical film (I) cannot be secured, and the reflection characteristics when laminated on the optical film (I) are not sufficient. Insufficient. Further, it is difficult to form a film having a refractive index lower than 1.3, and the refractive index 1.3 is the lower limit in manufacturing.
The thickness of the optical film is set to 80 nm to 15 μm, and more preferably, to 600 to 1000 nm.

  With the above configuration, the optical multilayer film has a high reflection characteristic with respect to light in three wavelength bands of red, green and blue, and a high transmission characteristic with respect to light in a visible wavelength region other than at least these wavelength regions. Will have. By adjusting the refractive index and the thickness of each of the optical film (I) and the optical film (II), it is possible to shift and adjust the wavelength position of the three wavelength bands reflected as the optical multilayer film. Accordingly, an optical multilayer film corresponding to the wavelength of light projected from the projector can be obtained.

  Note that the number of layers of the optical film (I) and the optical film (II) constituting the optical multilayer film is not particularly limited, and can be a desired number. Further, it is preferable that the optical multilayer film is constituted by an odd-numbered layer in which the outermost layer on the incident side of the projector light and on the opposite side is the optical film (I). When the optical multilayer film has an odd-numbered layer configuration, the function as a three-primary-color wavelength band filter is more excellent than in the case of an even-numbered layer configuration.

  The specific number of optical multilayer films is preferably an odd number of 3 to 7 layers. This is because when the number of layers is two or less, the function as the reflection layer is not sufficient. On the other hand, the reflectivity increases as the number of layers increases, but the rate of increase of the reflectivity decreases when the number of layers is 8 or more, and the effect of improving the reflectivity cannot be obtained as the time required for forming the optical multilayer film increases. .

(Reflective screen)
Next, an embodiment of the reflection screen according to the present invention will be described.
FIG. 1 shows a configuration example of the reflection screen according to the present invention. The reflection screen 10 has a configuration in which an optical multilayer film 12, a light absorption layer 13, and a light diffusion layer 14 are provided on a substrate 11.

  The substrate 11 may be any material that satisfies desired optical characteristics, such as a transparent film, a glass plate, an acrylic plate, a methacrylstyrene plate, a polycarbonate plate, and a lens. As the optical characteristics, the material constituting the substrate 11 preferably has a refractive index of 1.3 to 1.7, a haze of 8% or less, and a transmittance of 80% or more. Further, the substrate 11 may have an anti-glare function.

The transparent film is preferably a plastic film. Examples of the material forming the film include cellulose derivatives (eg, diacetyl cellulose, triacetyl cellulose (TAC), propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, and nitrocellulose), and polymethyl cellulose. (Meth) acrylic resins such as copolymers of methacrylate, methyl methacrylate with other alkyl (meth) acrylates and vinyl monomers such as styrene; polycarbonate resins such as polycarbonate and diethylene glycol bisallyl carbonate (CR-39); (Brominated) bisphenol A type di (meth) acrylate homopolymer or copolymer, (brominated) bisphenol A mono (meth) acrylate Thermosetting (meth) acrylic resins such as polymers and copolymers of tan-modified monomers; polyesters, especially polyethylene terephthalate, polyethylene naphthalate and unsaturated polyester; acrylonitrile-styrene copolymer, polyvinyl chloride, polyurethane, epoxy Resins and the like are preferred. Further, it is also possible to use an aramid resin in consideration of heat resistance. In this case, the upper limit of the heating temperature is 200 ° C. or higher, and the temperature range is expected to be wide.
The plastic film can be obtained by a method such as spreading these resins or diluting them in a solvent, forming a film, and drying. The thickness is preferably thicker in terms of rigidity, but is preferably thinner in terms of haze, and is usually about 25 to 500 μm.

  Further, the surface of the plastic film may be coated with a coating material such as a hard coat, and by having this coating material beneath an optical multilayer film composed of an inorganic substance and an organic substance, adhesion, hardness, It is also possible to improve various physical properties such as chemical resistance, durability and dyeability.

  Further, an undercoat layer may be provided on the substrate 11 as an optically functional thin film or a transparent support surface treatment. The undercoat layer includes an organoalkoxy metal compound, polyester, acryl-modified polyester, and polyurethane. Further, it is preferable to perform corona discharge and UV irradiation treatment.

  The optical multilayer film 12 is composed of a high refractive index optical film 12H obtained by applying and curing the material for a coating type optical film of the present invention on a substrate, and a low refractive index optical film 12L which is a fluorine-containing film. The configuration may be any as long as it is the configuration of the optical multilayer film described above.

  The light absorbing layer 13 is for absorbing light transmitted through the optical multilayer film 12. For example, in FIG. 1, a black resin film is attached to the surface of the substrate 11 opposite to the surface on which the optical multilayer film 12 is provided. The attached mode is shown.

Alternatively, the light absorption layer 13 may be a layer obtained by applying a black paint.
Examples of the black paint include fine particles having carbon black adhered to the surface thereof, such as carbon black fine particles and silica fine particles. These fine particles may have conductivity.
Further, as a method for producing carbon black fine particles, an oil furnace method, a channel method, a lamp method, a thermal method and the like are known.

  For the purpose of sinking black, the primary particle size and dispersibility of the fine particles are important factors that determine the black color of the coating film. The smaller the primary particle size and the larger the surface area, the better the jet blackness. In addition, carbon black with many surface functional groups has a high affinity for vehicles having polar functional groups such as OH groups and carboxyl groups, such as alkyd resins. The properties are improved, and the gloss and jetness are increased. It is also preferable to add a curing agent having an isocyanate group and a carboxyl group reactive with the functional group of the resin to cure the coating film.

  Generally, the amount of surface functional groups is larger in channel carbon than in furnace carbon, but the amount of functional groups can also be increased by performing an oxidation treatment in the furnace method. The primary particle size of the carbon black is preferably 30 nm or less, and more preferably 20 nm or less. As the particle diameter increases, the jetness decreases and the performance as a light absorbing layer decreases.

  The coating method may be a conventionally known method such as screen coating, blade coating, spray coating and the like.

  Further, the film thickness is preferably about 10 to 50 μm, and more preferably 15 to 25 μm. When the film thickness is smaller than 10 μm, jetness is reduced particularly in the case of spray coating. On the other hand, when the film thickness is larger than 50 μm, the coating film becomes brittle and cracks are easily generated.

The light-diffusing layer 14 has an uneven surface on one side, and the constituent material is not particularly limited as long as it has a property of transmitting light in a wavelength range used in the projector, and is usually used as a diffusion layer. Glass or plastic may be used. For example, a transparent epoxy resin may be applied on the optical multilayer film 12 and irregularities may be provided on the surface by embossing or the like, or a diffusion film having such a shape may be bonded. The light selectively reflected by the optical multilayer film 12 is diffused when transmitted through the light diffusion layer 14 and emitted, and a viewer can visually recognize a natural image by observing the diffused reflected light. become able to. The diffusion angle in the light diffusion layer 14 is an important factor that determines the visibility, and the diffusion angle is increased by adjusting the refractive index of the material constituting the diffusion plate and the unevenness of the surface.
When the light source of the projector is a laser, the surface shape pattern of the light diffusion layer 14 may be made random in order to prevent the generation of a speckle pattern which is a glare on the screen.

  The reflective screen 10 allows selective reflection of light of a specific wavelength from the projector and transmission / absorption of incident light in other wavelength regions such as external light, thereby lowering the black level of an image on the screen 10. Thus, a high-contrast image can be displayed even in a bright room. For example, when light from an RGB light source such as a diffraction grating type projector using a grating light valve (GLV) is projected, the screen 10 has a wide viewing angle, a high contrast, and a reflection of external light. There will be no good images to watch.

  That is, the light incident on the screen 10 passes through the light diffusion layer 14 and reaches the optical multilayer film 12, and the external light component included in the incident light is transmitted through the optical multilayer film 12 and is transmitted through the light absorption layer 13. The light is absorbed and selectively reflected only in light of a specific wavelength region related to an image, and the reflected light is diffused on the surface of the light diffusion layer 14 and provided to the viewer as image light having a wide viewing angle. Therefore, the influence of external light on the image light as the reflected light can be eliminated at a high level, and a higher contrast than before can be achieved.

Next, a method for manufacturing the reflective screen 10 according to the present invention will be described below.
(S1) A polyethylene terephthalate (PET) film is prepared as the substrate 11, and a predetermined amount of the material for a coating type optical film according to the present invention is applied to the main surface of the substrate 11.
(S2) After drying the coating film of the coating type optical film material, the coating film is irradiated with ultraviolet rays and cured to form the optical film 12H having a predetermined thickness.
(S3) Then, a predetermined amount of a fluorine-containing base layer coating material is applied on the optical film 12H.
(S4) After drying, the coating film is thermally cured to form an optical film 12L having a predetermined thickness. Thereby, a laminated structure of the optical film 12H and the optical film 12L is obtained.
(S5) Next, a predetermined amount of the coating type optical film material according to the present invention is applied onto the outermost optical film 12L of the substrate 11.
(S6) After drying the coating film of the coating type optical film material, the coating film is cured by irradiating ultraviolet rays to form an optical film 12H having a predetermined thickness. Thereafter, the processes of steps s3 to s6 are performed a predetermined number of times, and the optical multilayer film 12 is formed on the substrate 11.

(S7) A low-refractive-index transparent adhesive (EPOTEK396 manufactured by EPOXY TECHNOLOGY) is applied to the outermost layer surface of the optical multilayer film 12, and a surface opposite to the surface of the plate-shaped light diffusion layer layer 14 having irregularities is coated thereon. After mounting as a contact surface, the adhesive is cured to form an adhesive layer that bonds the optical multilayer film 12 and the light diffusion layer 14 together.

(S8) A resin containing a black light absorbing agent is applied to the back surface of the substrate 11 to form the light absorbing layer 13, thereby obtaining the reflection screen 10 according to the present invention.

  In the above manufacturing process, the coating-type optical film material can be uniformly applied on the substrate 11 or the optical film 12L having a low surface energy. That is, since the dispersant used in the material for the coating type optical film of the present invention has a predetermined relationship with the fine particles, the surface tension of the material for the coating type optical film is higher than the surface energy of the substrate 11 or the optical film 12L. The optical film 12H can be uniformly coated on the substrate 11 or the optical film 12L, and the desired optical film 12H can be formed. Can be obtained.

  In addition, as a method of applying the material for the coating type optical film, the material may be coated by a conventionally known coating method such as gravure coating, roll coating, blade coating, die coating, and dipping.

  Further, as a configuration of another embodiment of the reflection screen according to the present invention, as shown in FIG. 2, an optical multilayer film 12 having the same configuration as above is formed on both surfaces of a substrate 11, and one of the optical multilayer films 12 is formed. The optical diffusion layer 14 may be formed on the outermost layer surface of the optical multilayer film 12, and the light absorption layer 13 may be formed on the outermost layer surface of the other optical multilayer film 12. The reflective screen 20 also reflects light of a specific wavelength from the projector and transmits and absorbs incident light in other wavelength regions such as external light, thereby lowering the black level on the reflective screen to achieve high contrast. It is possible.

  When the substrate 11 is formed in the shape of a convex lens or a concave lens and the optical multilayer film 12 is formed on the surface thereof, the transmitted light beam is collected or diverged while selectively reflecting the incident light beam to form a real image or a virtual image. Can be an optical lens that can be connected, glasses (for correction, fashion), microscope, telescope, magnifier, projection equipment (movie, overhead projector, slide projector), camera (video camera, digital camera, photographic camera) , An endoscope camera), and an optical memory or reading objective lens mainly composed of a CD. In this case, the surface shape is not limited, and may be any of a spherical shape and an aspherical shape, and may be used in combination with another conventional lens.

  An example in which the present invention is actually implemented will be described below. This embodiment is an exemplification, and the present invention is not limited to this embodiment.

(Example 1)
The composition of the paint (I) comprising the material for the coating type optical film according to the present invention and the paint (II) which is the paint for the underlayer in Example 1, the production method and the optical film forming method are shown below.
(1) Paint (I)
Ultrafine: TiO ₂ fine particles (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle diameter of about 20 nm, refractive index 2.48) 100 parts by weight Dispersant: SO ₃ Na group-containing urethane acrylate (number average molecular weight: 350, SO ₃ Na Concentration: 1 × 10 ^-1 mol / g) 38 parts by weightBinder: mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (UV curable resin manufactured by Nippon Kayaku Co., Ltd., trade name: DPHA) 19 parts by weight, organic Solvent: Methyl isobutyl ketone (MIBK) 4800 parts by weight The fine particles, a dispersant and an organic solvent were mixed and subjected to a dispersion treatment with a paint shaker to obtain a fine particle dispersion. The fine particle dispersion was collected, and the average particle diameter was measured as a particle size distribution of TiO ₂ fine particles by a particle size distribution analyzer (UPA). Further, a binder was added to the fine particle dispersion, and the mixture was stirred with a stirrer to obtain a coating (I). The surface tension of the coating (I) was measured by a capillary method.

(2) Paint (II)
Binder: terminated polymer 100 parts by weight organic solvent perfluoro butenyl vinyl ether having a carboxyl group: a mixed solvent of the fluorine-containing alcohol _{(C 6 F 13 C 2 H} 4 OH) and perfluoro-butylamine (mixing ratio 95 : 5) 1666 parts by weight The above binder and an organic solvent were mixed and sufficiently stirred to obtain a paint (II).

(3) Optical Film Forming Method (s11) Paint (I) is applied to the main surface of a PET film (188 μm thick, trade name U426, manufactured by Toray Industries, Inc.).
(S12) After drying the coating film of the coating material (I) at 80 ° C., it is cured by ultraviolet light (UV) (1000 mJ / cm ² ) to form a high refractive index optical film (I) having a thickness of 1000 nm.
(S13) Then, a paint (II) is applied on the optical film (I).
(S14) After drying the coating film of the paint (II) at room temperature, it is thermally cured at 90 ° C. to form a low-refractive-index optical film (II) having a surface energy of 20 dyne / cm and a predetermined film thickness of 1100 nm ± 350 nm. .
(S15) Paint (I) is applied on the optical film (II).
(S16) After drying the coating film of the paint (I) at 80 ° C., it is cured by ultraviolet (UV) (1000 mJ / cm ² ) to form an optical film (I) having a thickness of 1000 nm and a high refractive index. Thus, a laminated film of the optical film (I) having a high refractive index and the optical film (II) having a low refractive index was obtained.
In evaluating the formed optical film, the refractive index of the optical film (I) formed at the end of the step s16 is measured with a fill metrics (manufactured by Matsushita Intertechno), and the haze is measured with a haze meter (JASCO V-560). Was measured.

(Example 2)
The coating material and the laminated film were obtained by setting the molecular weight of the dispersant in the coating material (I) of Example 1 to 110 and the addition amount to 22.0 μmol / m ² , and the other conditions were the same as those of Example 1.

(Example 3)
A coating material and a laminated film were obtained assuming that the molecular weight of the dispersant in the coating material (I) of Example 1 was 3000, the amount of addition was 2.2 μmol / m ² , and the other conditions were the same as those of Example 1.

(Example 4)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the fine particles in the coating material (I) of Example 1 was 2 wt%.

(Example 5)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the amount of the fine particles added in the coating material (I) of Example 1 was 8 wt%.

(Example 6)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the fine particles in the coating material (I) of Example 1 was 18 wt%.

(Example 7)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the amount of the dispersant added to the coating material (I) in Example 1 was 6.74 μmol / m ² .

(Example 8)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the amount of the dispersant added to the coating material (I) in Example 1 was 20.2 μmol / m ² .

(Example 9)
As a dispersant in paints (I) of Example 1, two kinds of dispersing agents, respectively 6.7μmol ^/ m 2 with a dispersing agent B of the dispersing agent A and a molecular weight of 1000 molecular weight 245, 1.5μmol / ^{m 2} was added The other conditions were the same as those in Example 1 to obtain a paint and a laminated film.

(Example 10)
ZrO ₂ was applied to the surface of the fine particle TiO ₂ in the paint (I) of Example 1 at a volume ratio of 22% to the TiO ₂ fine particles, and the other conditions were the same as those of Example 1 except that the paint and A laminated film was obtained.

(Example 11)
Al ₂ O ₃ was applied on the surface of the fine TiO ₂ particles in the paint (I) of Example 1 at a volume ratio of 22% to the TiO ₂ fine particles, and the other conditions were the same as those of Example 1. A paint and a laminated film were obtained.

(Example 12)
Fine particles in the paint (I) of Example 1 were ZrO ₂ , and the other conditions were the same as those of Example 1 to obtain a paint and a laminated film.

(Example 13)
In the paint (I) of Example 1, the amount of the dispersant having the hydrophilic group of POO (OH) ₂ was 2.2 μmol / m ² , and the other conditions were the same as those of Example 1, except that the paint and A laminated film was obtained.

(Example 14)
In the paint (I) of Example 1, the addition amount of the dispersant having the hydrophilic group of POO (OH) ₂ was 22.0 μmol / m ² , and the other conditions were the same as those of Example 1, except that the paint and A laminated film was obtained.

(Comparative Example 1)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the molecular weight of the dispersant in the coating material (I) of Example 1 was set to 100.

(Comparative Example 2)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the molecular weight of the dispersant in the coating material (I) of Example 1 was 3100.

(Comparative Example 3)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the fine particles in the coating material (I) of Example 1 was 0 wt%.

(Comparative Example 4)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the fine particles in the coating material (I) of Example 1 was 1 wt%.

(Comparative Example 5)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the fine particles in the coating material (I) of Example 1 was 20 wt%.

(Comparative Example 6)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the amount of the dispersant added in the coating material (I) of Example 1 was 2.0 μmol / m ² .

(Comparative Example 7)
A coating material and a laminated film were obtained under the same conditions as in Example 1 except that the addition amount of the dispersant in the coating material (I) of Example 1 was 25.0 μmol / m ² .

  Table 1 shows the results of Examples 1 to 14. In each of the examples, the coating material (I) could be uniformly applied on the lower optical film (II) without any problem, and a desired optical film (I) could be provided.

Table 2 shows the results of Comparative Examples 1 to 7. The results were as follows.
Comparative Example 1: The dispersant did not dissolve at the stage of preparing the paint (I), and the fine particles could not be dispersed.
Comparative Example 2: A decrease in dispersibility of the fine particles was observed at the stage of preparing the paint (I), and a normal coating film could not be obtained.
Comparative Example 3: The fine particles could not be properly dispersed at the stage of preparing the paint (I), and a normal coating film could not be obtained.
Comparative Example 7: The coating material (I) was applied on the optical film (II), but the refractive index of the optical film (I) was low.
Comparative Example 5: The dispersion of fine particles in the paint (I) was reduced due to the high solid content, and the optical film (I) could not be formed by the paint (I) due to poor dispersibility.
Comparative Example 6: A decrease in the dispersibility of the fine particles was observed at the stage of preparing the paint (I), and a normal coating film could not be obtained.
Comparative Example 7: The coating material (I) was applied on the optical film (II), but the refractive index of the optical film (I) was low.

  Next, an example in which an optical multilayer film and a reflective screen are actually manufactured based on the conditions of the first embodiment will be described below.

(Example 15)
Under the conditions for forming the optical film of Example 1, three optical multilayer films of optical film (I) / optical film (II) / optical film (I) were obtained on the PET film. The film thickness of the optical film (I) in this optical multilayer film was set to 600 nm, and the film thickness of the optical film (II) was set to 1000 nm, and the reflection characteristics of the obtained optical multilayer film were measured by Filmetrics (Matsushita Intertechno). did. As the reflection characteristics, the reflectance in the three primary color wavelength ranges of a blue wavelength of 480 nm, a green wavelength of 560 nm, and a red wavelength of 665 nm was measured.
In addition, a black PET film is adhered to the back surface of the PET film as a substrate via an adhesive layer on the obtained optical multilayer film, and a diffusion film is adhered to the outermost layer surface of the optical multilayer film via the adhesive layer. Then, a reflection screen was prepared, and the gain of this reflection screen was measured with a spectral radiance meter (CS-1000, manufactured by Minolta). Note that the gain is the maximum value of the ratio when the luminance (cd / m ² ) of the white plate when light is applied to the white plate is 1.
Further, the luminance of the screen was measured by the above luminance meter, and the contrast was obtained. That is, the luminance when the reflective screen is irradiated with white light from the projector is measured, then the luminance when the black light is irradiated from the projector is measured, and the ratio of the luminance when the white and black lights are irradiated is measured. Was measured for contrast.

(Example 16)
The number of laminated optical films in Example 15 was set to five layers of optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I). Under the same conditions as in Example 15, an optical multilayer film and a reflective screen were obtained.

(Example 17)
In Example 15, the number of laminated optical films was determined as follows: optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I ), And the other conditions were the same as those in Example 15 to obtain an optical multilayer film and a reflective screen.

(Example 18)
The optical multilayer film obtained in Example 15 was coated with a black paint by spray coating on the back side of the PET film, and dried and cured at 75 ° C. for 30 minutes to form a light absorbing layer.
The black paint used was obtained by adding a solvent to the following composition.
・ Carbon black fine particles: Origin plate manufactured by Origin Electric Co., Ltd.
(Primary particle diameter: 15 nm)
-Resin: Alkyd resin having a hydroxyl group A polyhard MH (isocyanate-based) manufactured by Origin Electric Co., Ltd. was used as a curing agent.
Next, a reflective screen was obtained by laminating a diffusion film on the optical multilayer film via an adhesive layer, and the same evaluation as in Example 15 was performed.

(Example 19)
The same processing as in Example 18 was performed on the optical multilayer film obtained in Example 16 to obtain a reflection screen, and the same evaluation was performed.

(Example 20)
The same processing as in Example 18 was performed on the optical multilayer film obtained in Example 17 to obtain a reflection screen, and the same evaluation was performed.

  Table 3 shows the reflectance of the optical multilayer film, the gain of the reflective screen, and the contrast as a result of Examples 15 to 20. The reflectivity of the optical multilayer film having a three-layer structure was 55%, and the reflectivity was increased as the number of layers increased. The reflectivity of 88% was obtained with the optical multilayer film having a seven-layer structure. Also, in the reflective screen, an increase in the gain was observed in proportion to the number of layers, and in the reflective screen having a seven-layer structure, a gain of 1.6 was obtained when the light absorbing layer was a black PET film (Example 17). In the case of a black coating film (Example 19), a gain of 1.9 was obtained. In each of the examples, high contrast was obtained.

FIG. 1 is a cross-sectional view illustrating a configuration of one embodiment of a reflection screen according to the present invention. FIG. 11 is a cross-sectional view illustrating a configuration of another embodiment of the reflection screen according to the present invention.

Explanation of reference numerals

10, 20: reflective screen, 11: substrate, 12: optical multilayer film, 12H, 12L
... optical film, 13 ... light absorption layer, 14 ... light diffusion layer

Claims (6)

A coating type optical film material for forming an optical film by coating on a fluorine-containing substrate,
Fine particles, an organic solvent, a binder that causes a curing reaction by absorbing energy, and a dispersant comprising a lipophilic group and a hydrophilic group having a chemical formula amount of 110 to 3000,
The material for a coating type optical film, wherein the content of the dispersant is 2.2 to 22 μmol / m ² with respect to the fine particles, and the surface tension when applied is 19 dyne / cm or less.   The hydrophilic group of the dispersant is a sulfonic acid group, a sulfonic acid group, a phosphoric acid group or a phosphoric acid group, a carboxylic acid group, a carboxylic acid group, for a coating type optical film according to claim 1. material.   The material for a coating type optical film according to claim 1, wherein the content of the fine particles is 2 to 20% by weight and the primary particle diameter is 100 nm or less.   2. The material for a coating type optical film according to claim 1, wherein the refractive index of the optical film obtained after the coating is 1.7 to 2.1.   An optical multilayer film comprising: an optical film obtained by applying the material for a coating type optical film according to claim 1; and a fluorine-containing film.   A reflection screen, comprising: a substrate, a light absorption layer, the optical multilayer film according to claim 5, and a light diffusion layer sequentially provided.

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