JP2005165253A - Coating material for optical film, optical multilayer film and reflective screen using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating material for an optical film which can be easily shaped, which has excellent productivity and a wide range for selecting a refractive index, which can be uniformly applied even on the surface of a substance having low surface tension, to provide an optical multilayered film formed by using the coating material, and to provide a reflective screen having the optical multilayer film. <P>SOLUTION: The coating material for an optical film contains pigment fine particles, an organic solvent, a binder which induces hardening reaction by absorbing energy, a dispersant having a lipophilic group and a hydrophilic group, and a fluorine-based surfactant having a perfluoro group and a hydrophilic group, in which the hydrophilic group of the dispersant and the hydrophilic group of the fluorine-based surfactant comprise atomic groups having a common element and an oxygen atom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

By applying an optical film having high transparency and various refractive indexes on the surface of the object with an arbitrary thickness, various functions can be imparted to the object.
For example, it is known that an effective antireflection film can be designed when a high refractive index film is present under a low refractive index film having a refractive index of 1.35 to 1.45 with respect to light having a wavelength of 550 nm (for example, , See Patent Document 1).

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

  It is also known that by alternately laminating layers having a low refractive index and layers having a higher refractive index, a certain wavelength region can be selectively and strongly reflected, and the object can be colored in any color. It has been.

  As one method for laminating such an optical film on a target substrate, there is a so-called liquid layer deposition method using a solid precipitation reaction from a liquid layer. The dip coating method, which is one of the liquid layer deposition methods, is known to be able to apply a coating film having a uniform film thickness and surface smoothness on the order of nm to a flat plate, Since the paint itself hardly changes chemically before and after coating, it is also effective for mass processing.

Japanese Patent Laid-Open No. 11-64601 JP 2000-171603 A

  However, even if an optical film is formed by a liquid layer deposition method to improve the surface characteristics of the optical material as described above, it may not be able to be laminated successfully, especially low surface tension substances such as fluorine-based films and release films. In many cases, it could not be laminated on the surface.

  The present invention has been made in view of the above problems in the prior art, and is easy to shape, excellent in productivity, freely selectable in a wide range of refractive index, and uneven on the surface of a low surface tension substance. An object of the present invention is to provide a coating material for an optical film that can be uniformly applied without any loss, an optical multilayer film formed using the same, and a reflective screen including the optical multilayer film.

The inventors have studied the above-mentioned problems in consideration of the affinity of the paint with respect to the substrate surface as well as the affinity of the paint with respect to a film formed of another paint.
Here, as a method of improving the affinity between the paint and the coating, a method of improving wettability by dissolving a surfactant having an effect of significantly reducing the surface tension on the paint side in advance is known. There are various types of surfactants having such an effect. For a substance having a very low surface tension of 20 dyne / cm or less such as a fluororesin, for example, a fluorine-based compound sharing a perfluoro group and a hydrophilic group. Surfactants are extremely effective.

  On the other hand, the coating material for optical films that is the subject of the present invention is added with a dispersant for increasing the repulsive force between the fine particles by adsorbing to the pigment fine particle surface and improving the affinity between the fine particle surface and the solvent. . Therefore, the inventors paid attention to the influence between the dispersant and the surfactant, and diligently studied the types that maintain the dispersibility of the pigment fine particles and improve the wettability, and combinations thereof, and the present invention. It came to be accomplished.

  That is, the present invention provided to solve the above problems includes pigment fine particles, an organic solvent, a binder that absorbs energy to cause a curing reaction, a dispersant having a lipophilic group and a hydrophilic group, A coating for optical film comprising a fluorosurfactant having a fluoro group and a hydrophilic group, wherein the hydrophilic group of the dispersant and the hydrophilic group of the fluorosurfactant have a common element and an oxygen atom An optical film coating material comprising an atomic group.

  The combination of the hydrophilic group of the dispersant and the hydrophilic group of the fluorosurfactant is a combination of acid groups containing pentavalent P or a combination of acid groups (including salts thereof) containing S. Is preferred.

Here, the content of the dispersant is preferably 1 to 5 μmol / m ² with respect to the surface area of the pigment fine particles.

  In addition, the content of the fluorosurfactant in which the hydrophilic group is an acid group containing pentavalent P is preferably 0.1 to 8 wt%, and the hydrophilic group contains an acid group containing S (a salt thereof) The content of the fluorosurfactant is preferably 1 to 5 wt%.

The pigment fine particles are preferably TiO ₂ or ZrO ₂ fine particles, and the pigment fine particle content is preferably ₂ to 18 wt%.

  Furthermore, the refractive index of the optical film obtained after coating is 1.6 to 2.1, and the present invention is preferably a coating material that is coated on a fluorine-containing material to form an optical film.

  Further, the present invention provided to solve the above-mentioned problems is that an optical film obtained by applying the optical film paint according to any one of claims 1 to 9 and a fluorine-containing film are laminated. Is an optical multilayer film characterized by

  Further, the present invention provided to solve the above-mentioned problems is characterized in that a support, a light absorption layer, the optical multilayer film according to claim 10 and a light diffusion layer are sequentially provided. It is a reflective screen.

According to the coating material for an optical film of the present invention, it is possible to apply a uniform film thickness with good wettability on a material having a low surface tension by optimizing the dispersant and the fluorosurfactant. In addition, since the dispersibility of the pigment fine particles is good, the refractive index can be freely selected, and an optical film having a high refractive index can be formed.
In addition, according to the optical multilayer film of the present invention, since the high refractive index optical film having the target refractive index and the low refractive index optical film are laminated, the optical multilayer film has high reflection characteristics with respect to light in a specific wavelength band. It is possible to form a functional optical film having high transmission characteristics by coating at least for light in the visible wavelength region other than these wavelength regions.
Also, according to the reflective screen of the present invention, selective reflection that reflects light of a specific wavelength from the projector and transmits / absorbs incident light in other wavelength regions such as external light is possible. It is possible to achieve a high contrast by lowering the black level of the video, and it is possible to display a video with a high contrast even in a bright room.

  Embodiments of the present invention will be described below. In addition, embodiment shown below is an illustration and is not limited to this.

(Coating for optical film)
The coating material for optical films according to the present invention is obtained by dispersing pigment fine particles with a dispersant in an organic solvent in which pigment fine particles and a binder are dissolved, and further adding a fluorine-based surfactant. Moreover, this coating material for optical films can be applied to substrates of all shapes such as films, plates, and lens shapes, and optical thin films, and after application, it becomes an optical film by a curing reaction.

  The pigment fine particles used in the present invention are metal oxide fine particles added to adjust the refractive index of the optical film after film formation, Ti, Zr, Al, Ce, Sn, La, In, Examples thereof include oxides such as Y, Sb, and Si, and alloy oxides such as In-Sn. Of course, even if an appropriate amount of elements such as Al and Zr added to Ti for the purpose of suppressing the photocatalyst is contained, the effect of the present invention is not disturbed.

The specific surface area of the pigment fine particles is preferably 55~85m ² / g, and more preferably a 75~85m ² / g. When the specific surface area is in the above range, it is possible to suppress the secondary particle diameter in the paint to 100 nm or less, more preferably 50 nm or less by the dispersion treatment of the fine particles, and an optical film excellent in transparency with little light scattering. Can be obtained.

  The pigment fine particle content is preferably 2 to 18 wt%.

The binder used in the present invention is a binder having a functional group that absorbs energy such as radiation or heat to cause a curing reaction, and is a thermosetting resin, ultraviolet (UV), electron beam (EB) curable type. Examples thereof include resins.
Examples of thermosetting resins or UV and EB curable resins include polystyrene resins, styrene copolymers, polycarbonates, phenol resins, epoxy resins, polyester resins, polyurethane resins, urea resins, melamine resins, polyamine resins, urea formaldehyde resins, etc. Is mentioned. Polymers having other cyclic (aromatic, heterocyclic, alicyclic, etc.) groups may also be used. Further, a resin containing fluorine or silanol group in the carbon chain may be used.

  Organic solvents used in the present invention 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, and acetic acid. Ester solvents such as propyl, ethyl lactate and ethylene glycol acetate are used. These organic solvents do not necessarily need to be 100% pure, and may contain impurities such as isomers, unreacted products, decomposed products, oxides, and moisture if they are 20% or less. In order to apply on a support having a low surface energy or an optical functional film, it is desirable to select a solvent having a lower surface tension, and examples thereof include methyl isobutyl ketone, methanol, and ethanol.

  The dispersant used in the present invention takes the form in which the excess dispersant is oriented at the paint interface as well as the dispersion of the pigment fine particles, and exhibits the effect of reducing the surface tension of the paint. The dispersant is composed of a lipophilic group and a hydrophilic group, and the introduction site of the polar functional group which is a hydrophilic group is not particularly limited.

The hydrophilic group of the dispersant is preferably —PO (OH) ₂ , —SO ₃ Na or the like, for example, a phosphate group or a sulfonate group.
When a dispersant having a hydrophilic group other than this is used, it is possible to disperse the pigment fine particles, but the pigment fine particles rapidly aggregate and solid-liquid-separate when a fluorosurfactant described later is added. There is a case.
Note that the dispersant may have a functional group for causing a curing reaction with the binder.

The content of the dispersant is to the surface area of the pigment particles is preferably ^{1~5μmol / m 2, 3~4μmol / m} 2 is particularly preferred. When the content is less than 1 μmol / m ² , sufficient dispersibility cannot be obtained in the optical film, and further, an effective surface tension lowering effect cannot be obtained. Conversely, if it exceeds 5 μmol / m ² , the surface tension decreases regardless of the dispersion state of the pigment fine particles, but the volume ratio of the dispersant in the coating film increases, so that the film refractive index decreases and the refractive index decreases. Since the adjustment range becomes narrow, the optical film stacking design becomes difficult. The molecular weight of the dispersant may be measured by a gel permeation chromatograph (GPC) method or the like.
When a binder other than the dispersant of the present invention is included, a polyfunctional polymer or monomer having many linking groups is preferable. These dispersants can be used singly or in combination of two or more.

The fluorosurfactant used in the present invention has a perfluoro group and a hydrophilic group.
Hydrophilic group of the fluorine-based _{surfactant, -PO (OH) 2, =} PO (OH), - SO 3 H, etc. _-SO 3 Na are preferred, for example phosphoric acid group, a phosphonic acid group, a sulfonic acid group, a sulfonic It is preferably either acid base.

  There are no particular restrictions on the atomic weight, structure, and hydrophilic group introduction site of the perfluoro group.

  The content of the fluorosurfactant is preferably 0.1 to 8 wt% when the hydrophilic group is an acid group containing pentavalent P. When the hydrophilic group is an acid group containing S (including a salt thereof), the content is preferably 1 to 5 wt%. If the content is less than the above lower limit content, it is not possible to obtain sufficient affinity for application to an object to be applied, particularly a fluororesin surface. If the upper limit content is exceeded, the dispersibility of the pigment fine particles may be significantly deteriorated as compared with the case where the content is low.

  When the content is higher than the amount dissolved in the solution, the insoluble solid content adheres to the surface of the coating film, which causes a decrease in in-plane uniformity of optical characteristics and film surface smoothness. Therefore, when the solubility of the fluorosurfactant is within the above concentration range, the content needs to be suppressed below the solubility.

The hydrophilic group of each of the dispersant and the fluorosurfactant used in the present invention is preferably composed of an atomic group having a common element and an oxygen atom, and particularly a combination of acid groups containing pentavalent P, or S It is preferable that it is a combination of acid groups (including salts thereof). Here, the acid group containing pentavalent P is —PO (OH) ₂ ══PO (OH). Moreover, the acid group containing S (including a salt thereof) includes —SO ₃ H, —SO ₃ Na, and the like. Examples of the combination include a phosphoric acid group and a phosphoric acid group, a phosphoric acid group and a phosphonic acid group, a sulfonic acid group and a sulfonic acid group, and a combination of a sulfonic acid group and a sulfonic acid group.
If an attempt is made to produce a paint by a combination other than this, the dispersion of the pigment fine particles is remarkably deteriorated, or sufficient affinity to a low surface tension substance cannot be obtained.

  The optical film coating material of the present invention is prepared by a kneading step, a dispersing step, and a mixing step provided before and after these steps. All raw materials such as pigment fine particles, binders and organic solvents used in the present invention may be added at the beginning or during any step. In addition, individual raw materials may be added in two or more steps. For dispersion and kneading, a conventionally known apparatus such as an agitator or a paint shaker is used.

(Optical multilayer film)
The optical multilayer film according to the present invention is a laminate of a high refractive index optical film (I) obtained by applying and curing the above optical film paint and a low refractive index optical film (II) which is a fluorine-containing film. It is the structure which is made. Specifically, the optical film (I) is first provided on the support, and then the optical film (II) is provided. Thereafter, the optical film (I) and the optical film (II) are alternately provided, and finally the optical film is provided. The structure is provided with the film (I), and is preferably 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 a curing reaction after the optical film paint is applied on a support or the optical film (II).
The thickness of this optical film is 80 nm to 15 μm, more preferably 600 to 1000 nm. This is because if the thickness is greater than 15 μm, the haze component due to fine particles that cannot be dispersed increases and the function as an optical film cannot be obtained.
The refractive index of this optical film is preferably 1.6 to 2.1. When the refractive index is higher than 2.1, the dispersibility of the fine particles is insufficient and the function as an optical film is impaired, and when the refractive index is lower than 1.6, necessary optical characteristics are obtained. It may not be possible.

The optical film (II) is a fluorine-containing film formed by a curing reaction after applying a predetermined undercoat paint on the optical film (I), or a silica, hollow fine particle-containing film, or the like.
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.
The film thickness of this optical film is 80 nm to 15 μm, more preferably 600 to 1000 nm.

  In the above configuration, the optical multilayer film has high reflection characteristics with respect to light in the three wavelength bands of red, green, and blue, and at least high transmission characteristics with respect to light in the visible wavelength range other than these wavelength ranges. Will have. In addition, by adjusting the refractive index and thickness of each of the optical film (I) and the optical film (II), it is possible to adjust by shifting the wavelength position of the three wavelength bands reflected as the optical multilayer film. Thus, an optical multilayer film corresponding to the wavelength of light projected from the projector can be obtained.

  In addition, 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 of layers. Further, the optical multilayer film is preferably composed of an odd-numbered layer in which the projector light incident side and the outermost layer on the opposite side are the optical film (I). When the optical multilayer film has an odd-numbered layer structure, the function as a three-primary-color wavelength band filter is superior to the even-numbered layer structure.

  The specific number of layers of the optical multilayer film is preferably 3 to 7 odd layers. This is because when the number of layers is 2 or less, the function as a reflective layer is not sufficient. On the other hand, the reflectivity increases as the number of layers increases, but the increase rate 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 is increased. .

(Reflective screen)
Next, an embodiment of the reflective screen according to the present invention will be described.
A configuration example of a reflective screen according to the present invention is shown in FIG. 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 support 11.

  The support body 11 should just satisfy | fill desired optical characteristics, such as a transparent film, a glass plate, an acrylic board, a methacryl styrene board, a polycarbonate board, a lens, and a fluororesin. As optical characteristics, the material constituting the support 11 preferably has a refractive index of 1.3 to 1.6, a haze of 8% or less, and a transmittance of 80% or more. Further, the support 11 may have an antiglare function.

  Materials for forming the transparent film include cellulose derivatives (eg, diacetylcellulose, triacetylcellulose (TAC), propionylcellulose, butyrylcellulose, acetylpropionylcellulose and nitrocellulose), polymethyl methacrylate, methyl methacrylate and other alkyls. (Meth) acrylic resins such as copolymers with vinyl monomers such as (meth) acrylate and 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 urethane-modified monomer polymer and copolymer, etc. Curable (meth) acrylic resins, polyesters, especially polyethylene terephthalate, polyethylene naphthalate, and unsaturated polyesters; acrylonitrile - styrene copolymers, polyvinyl chloride, polyurethane, and epoxy resin are preferable. 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 widened. The plastic film substrate can be obtained by a method of stretching these resins or diluting them in a solvent and forming a film into a film, followed by drying. The thickness is usually about 25 μm to 500 μm.

  Further, the plastic substrate surface as described above may be coated with a coating material such as a hard coat, and this coating material existing in the lower layer of the optical functional laminated film made of an inorganic substance and an organic substance allows adhesion and hardness. Various physical properties such as chemical resistance, durability and dyeability can be improved.

  The optical multilayer film 12 is formed by alternately laminating a high refractive index optical film 12H obtained by applying and curing the optical film paint of the present invention on a substrate and a low refractive index optical film 12L which is a fluorine-containing film. The configuration of the optical multilayer film described above may be used.

  The light absorption layer 13 is for absorbing the light transmitted through the optical multilayer film 12. For example, in FIG. 1, a black film is bonded to the surface of the support 11 opposite to the surface on which the optical multilayer film 12 is provided. Form.

Alternatively, the light absorption layer 13 may be a layer obtained by application using a black paint.
Examples of the black paint include fine particles in which carbon black is deposited on the surface, such as carbon black fine particles and silica fine particles. These fine particles may be conductive.
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 the black color, the primary particle size and dispersibility of the fine particles are the major factors determining the black color as the coating film, and the jet blackness is improved as the primary particle size is smaller and the surface area is larger. In addition, carbon black with many surface functional groups has high affinity with vehicles having polar functional groups such as OH groups and carboxyl groups like alkyd resins. Improved, gloss and jetness increase. Moreover, it is good to add the hardening | curing agent which has the isocyanate group and carboxyl group which are reactive with the functional group which the said resin has, and to harden a coating film.

  Generally, the amount of surface functional groups is larger in channel carbon than in furnace carbon. However, the amount of functional groups can be increased by performing oxidation treatment even in the furnace method. The primary particle diameter of carbon black is preferably 30 nm or less, and more preferably 20 nm or less. As the particle size 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 or spray coating.

  Moreover, about 10-50 micrometers is preferable and, as for a film thickness, More preferably, it is 15-25 micrometers. When the film thickness is smaller than 10 μm, the jetness is lowered 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 likely to occur.

  The light diffusing layer 14 is formed by applying a transparent resin on the optical multilayer film 12 and providing irregularities on the surface by embossing and bead coating. Alternatively, a film having a light diffusion function may be bonded.

  The reflection screen 10 enables selective reflection by reflecting light of a specific wavelength from the projector and transmitting / absorbing incident light in other wavelength regions such as outside light, thereby reducing the black level of the image on the screen 10. Thus, high contrast can be achieved, and an image with high contrast can be displayed even in a bright room. For example, when light from an RGB light source such as a diffraction grating projector using a grating light valve (GLV) is projected, the screen 10 has a wide viewing angle, high contrast, and reflection of external light. There will be no good video.

  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 by the light absorption layer 13. Only the light in a specific wavelength region related to the image is absorbed and selectively reflected, 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 that is the reflected light can be eliminated at a high level, and an unprecedented high contrast can be achieved.

Below, the manufacturing method of the reflective screen 10 which concerns on this invention is demonstrated below.
(S1) A polyethylene terephthalate (PET) film is prepared as the support 11, and a predetermined amount of the optical film paint according to the present invention is applied to the main surface of the support 11.
(S2) After drying the coating film of the optical film paint, it is cured by irradiation with ultraviolet rays to form an optical film 12H having a predetermined film thickness.
(S3) Next, a predetermined amount of fluorine-containing undercoat paint is applied onto the optical film 12H.
(S4) The coating film is dried and then thermally cured to form an optical film 12L having a predetermined thickness. Thereby, it becomes a laminated structure of the optical film 12H and the optical film 12L.
(S5) Next, a predetermined amount of the coating material for an optical film according to the present invention is applied onto the optical film 12L which is the outermost layer of the support 11.
(S6) After drying the coating film of the optical film paint, it is cured by irradiating with ultraviolet rays to form an optical film 12H having a predetermined film thickness. Thereafter, the processes from steps s3 to s6 are performed a predetermined number of times to form the optical multilayer film 12 on the support 11.

(S7) A transparent adhesive having a low refractive index (EPOTEK396 manufactured by EPOXY TECHNOLOGY) is applied to the outermost layer surface of the optical multilayer film 12, and the surface opposite to the uneven surface of the plate-shaped light diffusion layer 14 is formed 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 absorber is applied to the back surface of the support 11 to form the light absorption layer 13, thereby obtaining the reflective screen 10 according to the present invention.

  In the manufacturing process described above, the coating material for the optical film can be uniformly applied on the support 11 and the optical film 12L having a low surface energy, and the desired optical film 12H can be formed. An optical multilayer film having the following can be obtained.

  In addition, as a coating method of the coating type optical film material, other conventional coating methods such as dipping coating, gravure coating, roll coating, blade coating, and die coating may be used.

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

(Example 1)
The composition and production method of the coating material (I) comprising the coating material for optical films according to the present invention in Example 1 and the coating material (II) which is the coating material for the underlayer are shown below.
(1) Paint (I)
Pigment fine particles: TiO ₂ fine particles (Ishihara Sangyo Co., Ltd., average particle size of about 20 nm, refractive index 2.48) 72 parts by weightBinder: SO ₃ Na group-containing urethane acrylate (number average molecular weight: 350, SO ₃ Na concentration : 1 × 10 ⁻¹ mol / g) 32 parts by weight Organic solvent: 288 parts by weight of methyl isobutyl ketone (MIBK) Dispersant: Polyoxyether alkyl phosphate (molecular weight distribution 393 to 1039)
(Average molecular weight: 481, hydrophilic group PO (OH) ₂ ) 14 parts by weight Fluorosurfactant: trade name EF123A manufactured by Gemco Co., Ltd.
_{Structure; [Rf-SO 2 -A]} 2 -PO (OH) 2 parts · UV curable resin: mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name DPHA 19 parts by weight In the above structural formula, Rf is a structure composed of a perfluoro group, and A is a structure composed of an alkyl group or a benzene ring.

A predetermined amount of the pigment fine particles, the dispersant, the binder, and the organic solvent were mixed, and dispersion treatment was performed with a paint shaker to obtain a fine particle dispersion. Next, a fluorine-based surfactant was added to this dispersion, and after stirring with a stirrer, the secondary particle average diameter was measured with a particle size distribution meter (UPA, Nikkiso Co., Ltd.). At this time, those having an average diameter of 90 nm or more were regarded as poor dispersion, and the subsequent treatment was not performed.
Next, a UV curable resin was added, and the mixture was stirred with a stirrer to obtain paint (I).

(2) Paint (II)
・ Binder: Polymer of perfluorobutenyl vinyl ether having a terminal carboxyl group
100 parts by weight, organic solvent: mixed solvent of fluorine-containing alcohol (C ₆ F ₁₃ C ₂ H ₄ OH) and perfluorobutylamine (mixing ratio 95: 5) 1666 parts by weight The above binder and the organic solvent are mixed, The mixture was sufficiently stirred to obtain paint (II).

(3) Optical film forming method (s11) The paint (II) is applied by dipping on the main surface of a PET film (thickness: 188 μm, manufactured by Toray Industries, Inc., trade name: U426).
(S12) The coating film of the paint (II) is dried at 90 ° C. to form a base layer (optical film (II)) having a predetermined film thickness with a surface energy of 20 dyne / cm.
(S13) Next, the paint (I) is applied on the underlayer by a dipping method.
(S14) The coating film of paint (I) is dried at 80 ° C. and then cured by ultraviolet (UV) (1000 mJ / cm ² ) to form an optical film (optical film (I)) having a predetermined thickness. Thereby, a laminated film of the base layer and the optical film was obtained.

In the evaluation, after the completion of step s13, the wettability of the paint (I) to the underlayer was visually evaluated. Here, the symbol ○ indicates that the liquid level of the paint (I) spreads over the entire surface of about 3 square cm of the underlayer for 3 seconds after the pulling up, and symbol X indicates that it does not correspond to this. In addition, the process of step s14 was performed only in the case of a paint that was judged as “good” in the wettability evaluation.
Moreover, the refractive index of the obtained optical film was measured with Filmetrics (manufactured by Matsushita Intertechno Co., Ltd.).

(Examples 2 to 4)
The additive amount of the pigment fine particles in the paint (I) of Example 1 is finally set to 2, 4 and 8 wt%, respectively, and the other conditions are the same as those in Example 1 to obtain a paint and a laminated film. It was.

(Examples 5 and 6)
The additive amount of the dispersant in the coating material (I) of Example 1 is finally set to 2,4 μmol / m ^2, and the other conditions are the same as those in Example 1 to obtain the coating material and the laminated film. It was.

(Examples 7 and 8)
The dispersant in the paint (I) of Example 1 is polyoxyether alkyl phosphoric acid having an average molecular weight of 787, and the addition amount is finally set to 1,2.5 μmol / m ² respectively. Were the same as the conditions of Example 1 to obtain a paint and a laminated film.

Example 9
The fluorosurfactant in the paint (I) of Example 1 was made zonyl UR (structural formula; Rfx-PO (OH) y (where x + y = 3)) manufactured by DuPont Co., Ltd. The coating material and the laminated film were obtained with the other conditions being the same as those in Example 1.

(Examples 10 and 11)
The addition amount of the fluorosurfactant in the coating material (I) of Example 1 was finally set to 1,8 wt%, and the other conditions were the same as those in Example 1, Obtained.

(Example 12)
In the paint (I) of Example 1, 2.5 μmol / m ^{2 of} sodium dodecylbenzenesulfonate (hydrophilic group SO ₃ Na) having an average molecular weight of 348.5 was added as a dispersant, and Gemco ( Co., Ltd. product name EF101 (structural formula; Rf-SO ₃ H) was added so that the final concentration would be 1 wt%, and the other conditions were the same as those in Example 1, and a paint and a laminated film were obtained. It was.

(Examples 13 to 15)
The fluorine-based surfactant in the paint (I) of Example 13 was trade name EF103 (Structural Formula; Rf-SO ₃ Na) manufactured by Gemco Co., Ltd., and the addition amount was finally 1, 3, 5 wt%, respectively. The other conditions were the same as those in Example 12, and a paint and a laminated film were obtained.

(Example 16)
In the paint (I) of Example 1, ZrO ₂ was added as pigment fine particles so as to be 14 wt%, and the additive amount of the dispersant was further adjusted to 2.5 μmol / m ^2. Under the same conditions as in No. 1, a paint and a laminated film were obtained.

(Example 17)
The dispersant in the coating material (I) of Example 16 was polyoxyether alkyl phosphoric acid having an average molecular weight of 787, and the other conditions were the same as those in Example 16 to obtain a coating material and a laminated film.

(Example 18)
The primary particle diameter of the pigment fine particles in the coating material (I) of Example 1 is 50 nm, the addition amount is finally 4 wt%, and the dispersant is polyoxyether alkyl phosphoric acid having an average molecular weight of 787, and the addition amount is as follows. The coating material and the laminated film were obtained under the same conditions as in Example 1 except that the amount was ² μmol / m ² .

(Test Examples 1 and 2)
In the coating material (I) of Example 1, the amount of pigment fine particles added was finally set to 1,20 wt%, and the other conditions were the same as those in Example 1 to obtain a coating material and a laminated film. .

(Test Examples 3 and 4)
In the paint (I) of Example 1, the additive amount of the dispersant was set to 0.7 μmol / m ^2, and the other conditions were the same as those of Example 1, and a paint and a laminated film were obtained.

(Test Examples 5 to 8)
In the coating material (I) of Example 1, the addition amount of the fluorosurfactant is finally set to 0, 0.01, 0.05, and 10 wt%, respectively, and other conditions are the same as those in Example 1. In the same manner as above, a paint and a laminated film were obtained.

(Test Example 9)
In the paint (I) of Example 9, the addition amount of the fluorosurfactant was finally set to 0.05 wt%, and the other conditions were the same as those in Example 9, and the paint and the laminated film were used. Obtained.

(Test Examples 10 and 11)
In the coating material (I) of Example 13, the addition amount of the fluorosurfactant was finally set to 0.5 and 7 wt%, respectively, and the other conditions were the same as those in Example 13, A laminated film was obtained.

(Test Example 12)
In the coating material (I) of Example 1, 5 μmol / m ² of oleic acid (hydrophilic group COOH) having an average molecular weight of 282 was added as a dispersant, and the other conditions were the same as those in Example 1, and the coating material and laminated film Got.

(Test Example 13)
In the coating material (I) of Example 1, 5 μmol / m ^{2 of} sodium oleate (hydrophilic group COONa) having an average molecular weight of 304 was added as a dispersant, and the other conditions were the same as those in Example 1, and the coating material and the laminate A membrane was obtained.

(Test Example 14)
The fluorosurfactant in the paint (I) of Example 13 was made zonyl UR (structural formula: Rfx-PO (OH) y (where x + y = 3)) manufactured by DuPont Co., Ltd. The other conditions were the same as in Example 13 to obtain a paint and a laminated film.

(Test Example 15)
The fluorine-based surfactant in the paint (I) of Example 13 was trade name EF123A (Structural Formula: [Rf-SO ₂ (A)] ₂ -PO (OH)) manufactured by Gemco Co., Ltd., and addition of pigment fine particles The amount was finally 0.5 wt%, and the other conditions were the same as those in Example 13, and a paint and a laminated film were obtained.

(Test Example 16)
The added amount of the dispersant in the coating material (I) of Example 1 is 2.5 μmol / m ² , and the fluorosurfactant is trade name EF103 (structure formula: Rf—SO ₃ Na) manufactured by Gemco Co., Ltd. The coating amount and the laminated film were obtained with the addition amount finally set to 1 wt% and the other conditions being the same as those in Example 1.

(Test Example 17)
A trade name EF101 (structure formula; Rf-SO ₃ H) manufactured by Gemco Co., Ltd. was added as a fluorine-based surfactant in the coating material (I) of Example 16 so that the final concentration would be 1 wt%, and the others. The conditions were the same as those in Example 16, and a paint and a laminated film were obtained.

The results of Examples 1 to 18 are shown in Table 1.
In any of the examples, the secondary particle size was 90 nm or less, and it was possible to uniformly apply with good wettability on the underlayer, and a desired optical film could be formed.

The results of Test Examples 1 to 17 are shown in Table 2.
In any of the test examples, the coating material was poorly dispersed, or even when the dispersion was good, the wettability on the underlayer was poor.

  Next, an example in which an optical multilayer film and a reflective screen are actually produced based on the conditions of Example 1 will be described below.

(Example 19)
Using the coating material of Example 1, a three-layer optical multilayer film was obtained in the order of optical film (I) / optical film (II) / optical film (I) on a PET film. The optical film (I) was formed under the conditions of steps s13 and 14 in the optical film forming method of Example 1, and the optical film (II) was formed under the conditions of steps s11 and 12.

  In this optical multilayer film, the film thickness of the optical film (I) is 600 nm, the film thickness of the optical film (II) is 1000 nm, and the reflection characteristics of the obtained optical multilayer film are measured by Filmetrics (manufactured by Matsushita Intertechno Co., Ltd.). 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.

Moreover, about the obtained optical multilayer film, a black PET film is bonded to the back surface of the PET film as a substrate via an adhesive layer, and a diffusion film is bonded to the outermost surface of the optical multilayer film via an adhesive layer. A reflection screen having the configuration shown in FIG. 1 was prepared, and the gain of the reflection screen was measured with a spectral radiance meter (CS-1000, manufactured by Minolta). The gain is the maximum value of the ratio when the luminance (cd / m ² ) of the white plate when the white plate is irradiated with light is 1.

(Example 20)
The number of laminated optical films in Example 19 is five layers of optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I), and other conditions are carried out. Under the same conditions as in Example 19, an optical multilayer film and a reflective screen were obtained.

(Example 21)
The number of laminated optical films in Example 19 is the optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I) / optical film (II) / optical film (I 7), and the other conditions were the same as those in Example 19, and an optical multilayer film and a reflective screen were obtained.

(Example 22)
A black paint was applied to the optical multilayer film obtained in Example 19 by spray coating on the back side of the PET film, and kept at 30 ° C. for 30 minutes as a drying and curing process to form a light absorption layer.
The black paint used was obtained by adding a solvent to the following composition.
・ Carbon black fine particle: Origin Electric Co., Ltd.
(Primary particle size: 15 nm)
Resin: Alkyd resin having a hydroxyl group In addition, as a curing agent, product name Polyhard MH (isocyanate type) manufactured by Origin Electric Co., Ltd. was used.
Next, a diffusion film was bonded onto the optical multilayer film via an adhesive layer to obtain a reflective screen.

(Example 23)
The optical multilayer film obtained in Example 20 was treated in the same manner as in Example 22 to obtain a reflective screen.

(Example 24)
The optical multilayer film obtained in Example 21 was treated in the same manner as in Example 22 to obtain a reflective screen.

  Table 3 shows the reflectivity of the optical multilayer film and the gain of the reflective screen as the results of Examples 19-24. The reflectance of the optical multilayer film having a three-layer structure was 55%, and the reflectance was increased as the number of laminated layers was increased. The reflectance of 88% was obtained with the optical multilayer film having a seven-layer structure. Also, in the reflective screen, an increase in gain was recognized in proportion to the number of laminated layers. When the light absorbing layer was a black PET film (Example 21), a gain of 1.6 was obtained. In Example 24, a gain of 1.9 was obtained.

It is sectional drawing which shows the structure of one Embodiment of the reflective screen which concerns on this invention. It is sectional drawing which shows the structure of other embodiment of the reflective screen which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 ... Reflective screen, 11 ... Support body, 12 ... Optical multilayer film, 12H, 12L ... Optical film, 13 ... Light absorption layer, 14 ... Light diffusion layer

Claims (11)

A pigment fine particle, an organic solvent, a binder that absorbs energy to cause a curing reaction, a dispersant having a lipophilic group and a hydrophilic group, and a fluorosurfactant having a perfluoro group and a hydrophilic group. A coating for an optical film comprising:
A coating material for an optical film, wherein the hydrophilic group of the dispersant and the hydrophilic group of the fluorosurfactant are composed of an atomic group having a common element and an oxygen atom.   The combination of the hydrophilic group of the dispersant and the hydrophilic group of the fluorosurfactant is a combination of acid groups containing pentavalent P or a combination of acid groups (including salts thereof) containing S. The optical film paint according to claim 1. 2. The coating composition for an optical film according to claim 1, wherein the content of the dispersant is 1 to 5 μmol / m ² with respect to the surface area of the pigment fine particles.   2. The coating composition for an optical film according to claim 1, wherein the content of the fluorosurfactant in which the hydrophilic group is an acid group containing pentavalent P is 0.1 to 8 wt%.   2. The coating composition for an optical film according to claim 1, wherein the content of the fluorosurfactant in which the hydrophilic group is an acid group containing S (including a salt thereof) is 1 to 5 wt%. The coating material for an optical film according to claim 1, wherein the pigment fine particles are fine particles of TiO ₂ or ZrO ₂ .   The optical film paint according to claim 1, wherein the content of the pigment fine particles is 2 to 18 wt%.   The optical film paint according to claim 1, wherein the refractive index of the optical film obtained after coating is 1.6 to 2.1.   2. The coating material for an optical film according to claim 1, wherein the coating material is applied on a fluorine-containing material to form an optical film.   An optical multilayer film obtained by laminating an optical film obtained by applying the optical film paint according to claim 1 and a fluorine-containing film. A reflective screen comprising a support, a light absorbing layer, the optical multilayer film according to claim 10, and a light diffusing layer.

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