JP2020042259A - Display device - Google Patents

Abstract

To provide a display device that offers superior visibility.SOLUTION: Provided herein is a display device 1 comprising a display element 10, an optical film 13 with a heat conductive layer 12 disposed on a light exit side of the display element, and a heat dissipating member thermally grounded from a peripheral portion of the heat conductive layer; or a display device comprising a display element and an optical film with a heat conductive layer disposed on a light exit side of the display element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a display device.

  2. Description of the Related Art In recent years, image display devices such as liquid crystal display devices (Liquid Crystal Display; LCD) and organic EL display devices (organic Electro Luminescence display devices) have been used in a wide range of applications. It's being used.

  2. Description of the Related Art A liquid crystal display device generally has a liquid crystal cell portion having a color filter, a counter substrate, and a liquid crystal layer sandwiched therebetween (for example, Patent Document 1). Further, since the liquid crystal display device is a non-light emitting type, a light source such as a backlight is required, and display is performed using light emitted from the light source.

  Further, as an organic EL display device, a combination of an organic EL display element substrate having an organic EL display element and a color filter, an RGB separation method, and the like are known (for example, Patent Document 2). The organic EL display element has a basic structure of anode / organic EL layer / cathode, and emits light when a current flows through the organic EL display element. Thereby, an image is displayed on the display screen.

JP 2015-179219 A JP 2006-228705 A

  In the above-described organic EL display device, there is a problem that the brightness and color in the display screen are locally or non-uniformly between the center and the periphery, and the visibility is reduced due to conspicuous reflected light. Have begun to be reported. Similar reports have been made when a display device is used in a vehicle or the like.

  The present invention has been made in view of such circumstances, and has as its object to provide a display device with excellent visibility.

The present inventors have conducted intensive studies to solve the above-described problems, and found that various properties such as brightness, color, reflection directivity, and the like become non-uniform at a local portion in a display screen, The cause of the deterioration in visibility due to the non-uniformity of the performances near the center and near the edge of the screen is that the temperature inside the display device becomes locally non-uniform, or the temperature inside the display device is It has been found that the optical film inside the display device is deformed by heat due to a high temperature or the like, and this has been solved.
The causes of the high temperature inside the display device include heat generated from a light source when displaying an image on the display screen, heat generation due to light emission of the organic EL display element, and a case where the display device is exposed to a high temperature environment such as a car in summer. It is conceivable to be placed.

The present invention provides the following [1] and [2].
[1] A display device comprising: a display element; an optical film including a heat conductive layer, which is disposed on the light emitting surface side of the display element; and a heat radiating member that is thermally grounded from a peripheral portion of the heat conductive layer.
[2] A display device comprising: a display element; and an optical film including a radiant heat reflection layer, which is disposed on the light emitting surface side of the display element.

  According to the present invention, a display device having excellent visibility can be provided.

It is an outline sectional view showing an example of the display of Embodiment A of the present invention. It is a top view of an example of a heat conduction layer of Embodiment A. It is an outline sectional view showing an example of the display of Embodiment B of the present invention.

<Embodiment A>
The display device according to the embodiment A of the present invention includes a display element, an optical film including a heat conductive layer disposed on the light emitting surface side of the display element, and a heat radiation thermally grounded from a peripheral portion of the heat conductive layer. And a member.
Hereinafter, the optical film including the heat conductive layer of the embodiment A may be referred to as “optical film A”.
In the embodiment A, the non-uniformity of the temperature inside the display device locally or the overall temperature inside the display device is suppressed mainly by the conduction action of the free electrons.

  FIG. 1 is a schematic cross-sectional view illustrating an example of the display device of the embodiment A. The display device 1 of FIG. 1 includes an optical film 13 in which a transparent base material 11 and a heat conductive layer 12 are laminated in this order on the light emitting surface side of a display element 10. The heat conductive layer 12 is thermally grounded to a heat radiating member 16 via a conductor 15 from a peripheral portion 14 thereof.

[Heat earth]
As the thermal grounding (grounding), as shown in FIG. 1, a method of connecting the thermal conduction layer 12 to the heat radiating member 16 from the peripheral portion 14 outside the image display region can be mentioned. At this time, the peripheral portion 14 of the heat conductive layer 12 and the heat radiating member 16 may be directly connected, or may be connected via the conducting wire 15. Further, it is preferable that the conductive wire 15 is fixed to the peripheral portion 14 of the heat conductive layer 12 by a conductive adhesive material having conductivity by free electrons such as a silver paste, a carbon tape, and a metal tape.
The thermal ground may be at one location on the peripheral edge portion 14 of the heat conductive layer 12 or at multiple locations.

(Heat dissipation member)
The heat dissipating member is a member for dissipating heat generated inside the display device from the heat conductive layer to the outside of the display device.
The heat dissipating member is not particularly limited as long as it is a substance having a conduction action by free electrons. For example, metals such as gold, silver, copper, aluminum, iron, nickel, and chromium, and alloys of these metals (for example, , Nichrome) and the like, and composite members containing these metals and metal alloys.

The heat dissipation member preferably has a volume resistivity of 1.0 × 10 ⁶ Ωm or less, more preferably 1.0 × 10 ³ Ωm or less, from the viewpoint of more effectively performing thermal grounding. It is more preferably 0 Ωm or less, particularly preferably 1.0 × 10 ⁻³ Ωm or less.
In the embodiment A, it is preferable that the heat radiation member also serves as the casing (outer frame) of the display device.

(Optical film A)
The optical film A includes at least a heat conductive layer. The optical film A preferably has a heat conductive layer on a transparent substrate. The optical film A may further have a functional layer described below.

(Heat conduction layer)
The heat conductive layer used in the embodiment A has a function of dissipating heat generated inside the display device to the outside of the display device, and transmits heat from a high temperature region to a low temperature region in a high temperature region and a low temperature region generated inside the display device. This is a layer having a function of making the temperature uniform, and having visible light transmittance enough to allow a display image on a display panel to be viewed.
Examples of the heat conductive layer include, for example, a layer containing a metal material and having adjacent metal materials having contact points, among which, in a transparent resin, adjacent metal nanowires are dispersed so as to have contact points. A metal nanowire layer or a layer formed of a metal material in a mesh shape is preferable. As the transparent resin, for example, a cover resin described later can be used.

When the heat conductive layer is formed as described above, heat generated inside the display device is efficiently radiated to the outside of the display device due to the movement of free electrons in the heat conductive layer, and generated inside the display device. In the high-temperature region and the low-temperature region, heat is efficiently transmitted from the high-temperature region to the low-temperature region, the temperature becomes uniform, and the occurrence of heat unevenness is prevented. Then, by preventing the occurrence of heat unevenness, deformation of the optical film is suppressed. Note that a metal oxide film of ITO or the like generally used as a transparent conductive layer does not have a high heat transfer function because free electrons move little.
In order to improve the heat conduction performance, it is preferable that the free electron density is high (the conductivity is high). Therefore, the surface resistivity of the heat conductive layer is preferably set to 250Ω / □ or less, more preferably 150Ω / □ or less, and further preferably 100Ω / □ or less.
The surface resistivity can be measured, for example, using a resistivity meter Loresta manufactured by Mitsubishi Chemical Corporation in accordance with JIS K7194: 1994 (a resistance test method for conductive plastics by the 4-deep needle method).

  Examples of the metal material include metals such as gold, silver, copper, iron, nickel, and aluminum, and alloys thereof. From the viewpoint of thermal conductivity, silver, copper, and aluminum are preferred, and silver is more preferred. The shape of the metal material is not particularly limited, but is preferably a metal nanowire from the viewpoint of transparency and heat conductivity. In particular, silver nanowires are preferable in that they have high reflectivity for near-infrared rays and are easy to suppress the generation of heat, and are excellent in bending resistance and are easily applied to a foldable display.

The average diameter of the metal nanowire is preferably 200 nm or less. By setting the average diameter of the metal nanowires to 200 nm or less, it is possible to suppress an increase in haze. The more preferable lower limit of the average diameter of the metal nanowire is 10 nm or more from the viewpoint of thermal conductivity, and the more preferable range of the average diameter of the metal nanowire is 15 nm or more and 180 nm or less.
The length of the metal nanowire is preferably 1 μm or more. By setting the length of the metal nanowire to 1 μm or more, a long heat conduction path can be formed by one metal nanowire. The preferable upper limit of the length of the metal nanowire is 500 μm or less from the viewpoint of light transmittance.
The length of the metal nanowire is more preferably 3 μm or more and 300 μm or less, and further preferably 10 μm or more and 30 μm or less.

  The diameter of the metal nanowire is obtained, for example, by measuring the diameter of 50 metal nanowires at a magnification of 1000 to 500,000 using a transmission electron microscope (TEM) and obtaining the average value of the diameters of the 50 metal nanowires. And For example, the length of the metal nanowire is measured using a scanning electron microscope (SEM) at a magnification of 1,000 to 500,000 times, and the average value of the lengths of the 50 metal nanowires is measured. Shall be obtained.

  The method for producing the metal nanowire may be any known method, and is not particularly limited.

The metal nanowire layer may contain other components such as a cover resin in addition to the metal nanowire.
The cover resin covers the metal nanowires to such an extent that electrical continuity is obtained from the surface of the metal nanowire layer, thereby preventing the metal nanowires from being detached from the metal nanowire layers, and having the durability and abrasion resistance of the metal nanowire layers. Is contained in the metal nanowire layer as needed in order to improve the density.

The thickness of the cover resin is preferably from 10 nm to less than 300 nm, and more preferably from 50 nm to 200 nm.
The thickness of the cover resin is determined by using a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), or a transmission electron microscope (TEM) at a magnification of 1,000 to 500,000 times. , The thickness is randomly measured at 10 points, and the average value of the measured thicknesses at 10 points is obtained.

  The cover resin is not particularly limited as long as it is a resin having a light transmitting property, and includes a resin containing a polymer of a polymerizable compound (cured product, cross-linked product). The cover resin may include a solvent-dried resin in addition to the polymer of the polymerizable compound. Examples of the polymerizable compound include an ionizing radiation polymerizable compound and / or a thermopolymerizable compound.

  The ionizing radiation polymerizable compound has at least one ionizing radiation polymerizable functional group in one molecule. The "ionizing radiation polymerizable functional group" in the present specification is a functional group capable of undergoing a polymerization reaction upon irradiation with ionizing radiation. Examples of the ionizing radiation polymerizable functional group include an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group, and an allyl group. In addition, "(meth) acryloyl group" is meant to include both "acryloyl group" and "methacryloyl group". In addition, examples of the ionizing radiation irradiated when polymerizing the ionizing radiation polymerizable compound include visible light, ultraviolet light, X-ray, electron beam, α-ray, β-ray, and γ-ray.

  Examples of the ionizing radiation-polymerizable compound include an ionizing radiation-polymerizable monomer, an ionizing radiation-polymerizable oligomer, and an ionizing radiation-polymerizable prepolymer. These can be appropriately adjusted and used. As the ionizing radiation polymerizable compound, a combination of an ionizing radiation polymerizable monomer and an ionizing radiation polymerizable oligomer or an ionizing radiation polymerizable prepolymer is preferable.

  Examples of the ionizing radiation polymerizable monomer include monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and ethylene glycol di (meth) acrylate. , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) ) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaery Ritorutetora (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) (meth) acrylic acid esters such as acrylate.

  As the ionizing radiation polymerizable oligomer, a polyfunctional oligomer having two or more functional groups is preferable, and a polyfunctional oligomer having three (trifunctional) or more ionizing radiation polymerizable functional groups is preferable. Examples of the polyfunctional oligomer include polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate. (Meth) acrylate, epoxy (meth) acrylate, and the like.

  The ionizing radiation polymerizable prepolymer has a weight average molecular weight exceeding 10,000, and the weight average molecular weight is preferably from 10,000 to 80,000, more preferably from 10,000 to 40,000. When the weight average molecular weight is more than 80,000, the viscosity is high, so that the coating aptitude deteriorates, and the appearance of the obtained cover resin may be deteriorated. Examples of the polyfunctional prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

  The thermopolymerizable compound has at least one thermopolymerizable functional group in one molecule. The “thermopolymerizable functional group” in the present specification is a functional group capable of undergoing a polymerization reaction between the same functional group or another functional group by heating. Examples of the thermopolymerizable functional group include a hydroxyl group, a carboxyl group, an isocyanate group, an amino group, a cyclic ether group, and a mercapto group.

  The thermopolymerizable compound is not particularly limited, and examples thereof include an epoxy compound, a polyol compound, an isocyanate compound, a melamine compound, a urea compound, and a phenol compound.

  The solvent-drying type resin is a resin such as a thermoplastic resin which becomes a film only by drying a solvent added for adjusting the solid content at the time of coating. When the solvent-drying type resin is added, it is possible to effectively prevent a coating defect on a coating surface of the coating liquid when forming the cover resin. The solvent drying type resin is not particularly limited, and generally, a thermoplastic resin can be used.

Examples of the thermoplastic resin include a styrene resin, a (meth) acrylic resin, a vinyl acetate resin, a vinyl ether resin, a halogen-containing resin, an alicyclic olefin resin, a polycarbonate resin, a polyester resin, and a polyamide resin. , Cellulose derivatives, silicone resins and rubbers or elastomers.
The thermoplastic resin is preferably non-crystalline and soluble in an organic solvent (especially a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoints of transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (such as cellulose esters), and the like are preferable.

The metal nanowire layer preferably contains a reaction inhibitor.
After the application of the composition for a cover resin, the reaction inhibitor is formed by applying the metal nanowires to a substance or the like in the atmosphere (sulfur, oxygen, halogen in the atmosphere, or the adhesive layer when the conductive layer and the adhesive layer are in contact with each other). (Constituting material) to suppress the decrease in conductivity.
Examples of the reaction inhibitor include nitrogen-containing compounds such as benzoazole compounds, triazole compounds, tetrazole compounds, isocyanuric acid compounds, and aniline compounds. Examples of the nitrogen-containing compound used as the reaction inhibitor include 1-aminobenzoazole, 5-methylbenzotriazole, 1,2,3-benzotriazole, 1-methyl-1H-tetrazol-5-amine, DL-α -Tocopherol, 1-octadecanethiol, 2-mercapto-5- (trifluoromethyl) pyridine, diallyl isocyanurate, diallyl isocyanurate, 6-anilino-1,3,5-triazine-2,4-dithiol, thiocyanuric acid , 3,5-dimethyl-1H-1,2,4-triazole, 4- (1,2,4-triazol-1-ylmethyl) aniline, 6- (dibutylamino) -1,3,5-triazine-2 , 4-Dithiol, 4- (1,2,4-triazol-1-yl) aniline, 2-methylthio-benzothiazole, 1 Phenyl-5-mercapto-1H-tetrazole, 5-mercapto-1-methyltetrazole, 5- (methylthio) -1H-tetrazole, 5-amino-1H-tetrazole, 1- (2-dimethylaminoethyl) -5-mercapto Tetrazole, 1- (2-dimethylaminoethyl) -5-mercaptotetrazole, 1- (4-hydroxyphenyl) -5-mercapto-1H-tetrazole, 3-amino-5-mercapto-1,2,4-triazole, 3,5-diamino-1,2,4-triazole.

  The content of the reaction inhibitor in the metal nanowire layer is preferably from 0.01% by mass to 10% by mass. By setting the content of the reaction inhibitor to 0.01% by mass or more, it is possible to suppress the metal nanowires from reacting with a substance in the atmosphere. Further, by setting the content of the reaction inhibitor to 10% by mass or less, the reaction between the metal nanowire and the reaction inhibitor proceeds not only on the surface of the metal nanowire but also inside the metal nanowire, and it is possible to suppress a decrease in thermal conductivity. .

  The thickness of the metal nanowire layer is preferably from 10 nm to less than 300 nm, and more preferably from 50 nm to 200 nm.

  The method for forming the heat conductive layer in a mesh shape is not particularly limited. For example, a metal foil, a metal deposition film by vapor deposition, sputtering, etc., a metal plating film by electrolytic plating, electroless plating, or a metal vapor deposition A method of patterning a metal layer by etching such as a combination of a metal plating film on a film and the like, a method of printing an ink or a paste containing a metal in a mesh shape, and the like are given. Further, in order to further enhance the transparency, the metal nanowire layer may be patterned by etching.

The shape of the heat conductive layer as a mesh is not particularly limited, and a square is typical as the shape of the opening of the mesh. The shape of the opening in a plan view is, for example, a regular pattern having a periodic pattern such as a triangle such as an equilateral triangle, a square such as a rectangle, a rhombus, a trapezoid, or a polygon such as a hexagon, or an opening having a random shape. And the like. The mesh has a plurality of openings having these shapes, and between the openings, a line-shaped line having a generally uniform width is formed. If a specific size is illustrated, the width of the line portion between the openings is preferably 1 to 100 μm, more preferably 3 to 50 μm, from the viewpoint of thermal conductivity and invisibility of the mesh. The size of the opening is [line pitch]-[line width], where the [line pitch] is 100 μm to 500 μm, and the opening ratio (total area of opening / total area of mesh part) is 50. The content is preferably set to 97% from the viewpoint of compatibility between light transmittance and thermal conductivity. The line pitch may be random between 100 μm and 500 μm.
Note that the bias angle (the angle formed between the line portion of the mesh and the outer periphery of the heat conductive layer) may be appropriately set to an angle at which moire is less likely to occur in consideration of the pixel pitch and light emission characteristics of the display.

As conceptually illustrated in the plan view of FIG. 2, the heat conductive layer 12 is preferably a layer having a grounding region 122 at a peripheral portion other than the central transparent heat conductive region 121 in the plane direction. It is preferable because it is easy to take a thermal ground. The grounding area is formed on a part or the entire periphery of the image display area so as not to hinder image display.
Here, the transparent heat conductive region is a region that can cover the entire image display region of the display to which the heat conductive layer is applied. The grounding area is an area for grounding.
It should be noted that the grounding region is basically preferably as high as the thermal conductivity is higher, and transparency is not required. However, for the purpose of preventing warping of the grounding region, it is preferable to form the grounding region from the same material as the transparent heat conductive region. .

  The thickness of the heat conductive layer is not particularly limited as long as the free electrons of the heat conductive layer and the heat radiating member are shared.

(Transparent substrate)
The transparent base material supports the heat conductive layer.
The transparent substrate preferably has light transmittance, smoothness, heat resistance, and is excellent in mechanical strength. Examples of such a transparent substrate include polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, and polyvinyl acetal. , Polyether ketone, polymethyl methacrylate, polycarbonate, polyurethane, and a plastic film such as amorphous olefin (Cyclo-Olefin-Polymer: COP). The transparent substrate may be a laminate of two or more plastic films.
Among these plastic films, stretched, especially biaxially stretched polyester (polyethylene terephthalate, polyethylene naphthalate) is preferred in terms of excellent mechanical strength and dimensional stability. In the case where the display device is a foldable type, the plastic film is preferably polyimide having excellent flexibility.

  Further, among plastic films, a plastic film having a retardation value of 3000 to 30000 nm or a plastic film having a quarter-wave retardation has a different color on the display screen when an image is observed through polarized sunglasses. This is preferable because it can be prevented.

The thickness of the transparent substrate is preferably from 5 to 300 μm, more preferably from 30 to 200 μm.
The thickness of the transparent substrate can be calculated, for example, by measuring the thickness at 10 locations from an image of a cross section taken using a scanning transmission electron microscope (STEM) and averaging the values at 10 locations. It is preferable that the STEM has an acceleration voltage of 10 kv to 30 kV and a magnification of 100 to 700 times.
Further, the transparent substrate may have been subjected to a known easy adhesion treatment such as a corona discharge treatment, a primer treatment, and a base treatment on the surface thereof.

(Other layers)
The optical film A may further have a functional layer such as an antiglare layer, an antireflection layer, an antistatic layer, a refractive index adjusting layer, a hard coat layer, an antifouling layer, and a circularly polarizing plate.
The position of the functional layer in the display device is preferably closer to the surface than the heat conductive layer. When the optical film A has a functional layer, it is preferable that the optical film A has a heat conductive layer on the display element side of the transparent substrate and has a functional layer on the surface side of the transparent substrate.

(optical properties)
The optical film A preferably has a total light transmittance of 70% or more, more preferably 80% or more, even more preferably 90% or more according to JIS K7361-1: 1997.
Further, the optical film A preferably has a haze of JIS K7136: 2000 of 5% or less, more preferably 3% or less, further preferably 1% or less.

(Position of optical film A)
In the display device of Embodiment A, it is preferable that the display element and the optical film including the heat conductive layer (optical film A) are in contact with each other directly or via an adhesive layer.
With this configuration, a display element (for example, a self-luminous organic EL display element, a micro LED display element, or a large display element with a diagonal size of 50 inches or more) that generates a large amount of heat from the light emission surface side is provided. It can be easily suppressed that the temperature inside the display device becomes locally uneven or the temperature inside the display device becomes high as a whole. The adhesive layer in this configuration can be used without any particular limitation as long as it has optical transparency, but an adhesive layer having conductivity is preferable. The thickness of the adhesive layer is about 5 to 300 μm.

(Position of heat conduction layer)
When the optical film A has a multilayer structure having the above-described functional layer, the position of the heat conductive layer is not particularly limited. However, from the viewpoint of easily exhibiting the effects of the present invention, it is preferable to provide the heat conductive layer at a position close to the heat source. . Specifically, the heat conductive layer is preferably provided at a position adjacent to the display element.
For example, when the display element is a self-luminous organic EL display element, the organic EL display element generates heat when emitting light, as described later. Therefore, when an organic EL display element is used as the display element, it is preferable to provide the heat conductive layer at a position adjacent to the organic EL display element. Also, when the display element is a micro LED display element, or when the display element is a large display element having a diagonal size of 50 inches or more, it is preferable to provide the heat conductive layer at a position adjacent to the display element.

When another functional layer is provided between a display element such as an organic EL display element and the heat conductive layer, it is preferable to include conductive fine particles having a conductive action by free electrons in the functional layer. Thereby, while the heat generated in the display element such as the organic EL display element is transferred to the heat conductive layer, the heat is efficiently transmitted from the high temperature area to the low temperature area in the high temperature area and the low temperature area generated in the functional layer, The temperature can be made uniform, and the occurrence of heat unevenness can be prevented.
The conductive fine particles are not particularly limited, and, for example, coated fine particles having a conductive coating layer formed on the surface of core fine particles are preferably used.
The core fine particles are not particularly limited, and examples thereof include colloidal silica fine particles, inorganic fine particles such as silicon oxide fine particles, fluororesin fine particles, acrylic resin particles, polymer fine particles such as silicone resin particles, and fine particles such as organic inorganic composite particles. . In addition, examples of the material forming the conductive coating layer include metals such as Au, Ag, Cu, Al, Fe, Ni, Pd, and Pt, and alloys thereof.

In addition, when the display device of the embodiment A is mounted on a vehicle, it is possible to prevent a rise in temperature due to external light by providing the above-described heat conductive layer near the outermost surface of the display device. Thereby, it is possible to suppress a difference in a dimensional change in a vertical direction and a horizontal direction based on a difference in a stretching magnification of the transparent base material, and to prevent deformation of a display screen.
Further, by using a plastic film having a retardation value of 3000 to 30000 nm or a plastic film having a quarter-wave retardation as the above-mentioned transparent base material, it can be used for polarized sunglasses and is more suitable for use in vehicles.

(Other optical films)
The display device of Embodiment A has, apart from the above-described optical film A, other components having functional layers such as an antiglare layer, an antireflection layer, an antistatic layer, a refractive index adjusting layer, a hard coat layer, and an antifouling layer. An optical film may be further provided. In this case, the optical film having the heat conductive layer (optical film A) is preferably provided at a position close to the heat generation source. The other optical film A provided in the embodiment A may be an optical film B described later.

(Display element)
Examples of the display element used in the embodiment A include a liquid crystal display element, an organic EL display element, and a micro light emitting diode display element (micro LED display element). Examples of the liquid crystal display element include an IPS (In Plane Switching) mode liquid crystal display element and an FFS (Fringe Field Switching) mode liquid crystal display element. As the organic EL display element, for example, a translucent first electrode ( An anode, an organic light-emitting layer including a light-emitting layer, and a second electrode (cathode) are sequentially stacked on the surface of a light-transmitting substrate.

In an organic EL display element, an organic light emitting layer between both electrodes emits light by applying a current between a cathode and an anode. At this time, energy that does not contribute to light emission is generated as heat, and the inside of the display device may become hot. In particular, in the case of an RGB separation method in which a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are planarly arranged as light-emitting layers of an organic EL display element, the energy required for light emission differs for each color. As a result, the heat generated differs, so that a high-temperature region and a low-temperature region are generated in the display screen, and heat unevenness may occur (especially when a still image is displayed, the heat unevenness is likely to be remarkable). Therefore, when the display element is an organic EL display element, the effects of the present invention can be more remarkably exhibited.
In addition, since the micro LED display element displays an image using a large number of LED chips, the temperature is inevitably high. Therefore, when the display element is a micro LED display element, the effects of the present invention can be more remarkably exhibited.
In addition, even when the display element is a large display element having a diagonal size of 50 inches or more, the temperature inside the display element is likely to be high, so that the effects of the present invention can be more remarkably exhibited.

  The display device of the embodiment A is provided with an optical film having the above-described heat conductive layer on the light emitting surface side of the display element, thereby radiating heat generated inside the display device or heat caused by external light to the outside of the display device. As a result, the temperature in the display screen can be made uniform. Thereby, since there is no local deformation due to the non-uniform temperature in the display screen, there is no local non-uniformity in brightness and color, and in particular, there is no distortion of the reflected external video, A display screen without a sense of incongruity can be obtained. In particular, when the display element is an organic EL display element, a micro LED display element, a diagonal of 50 inches or more, or when the display device is mounted on a vehicle, the effect can be remarkably exhibited.

  The display device of the embodiment A preferably has a general-purpose heat radiation mechanism on the side opposite to the light emitting surface of the display element from the viewpoint of more easily exerting the effects of the present invention. The general-purpose heat radiation mechanism includes an air cooling fan, a heat radiation fin, a heat pump, a Peltier device, and the like.

<Embodiment B>
The display device according to Embodiment B of the present invention is characterized by having a display element and an optical film including a radiant heat reflection layer, which is disposed on the light emitting surface side of the display element.
Hereinafter, the optical film including the radiation heat reflection layer of the embodiment B may be referred to as “optical film B”.
In the embodiment B, the radiant heat is mainly reflected by the radiant heat reflecting layer, so that the optical film B is prevented from having a high temperature due to the radiant heat.

  FIG. 3 is a schematic sectional view illustrating an example of the display device of the embodiment B. The display device 1 in FIG. 3 has an optical film 19 including a radiant heat reflection layer 17 on the light emitting surface side of the display element 10. In FIG. 3, the optical film 19 has a radiant heat reflection layer 17 and a functional layer 18 on the transparent substrate 11. The display device 1 of FIG. 3 has another optical film 20 between the display element 10 and the optical film 19.

(Optical film B)
The optical film B includes at least a radiation heat reflection layer. The optical film B preferably has a radiation heat reflection layer on a transparent substrate. The optical film B may further have a functional layer described later.
Embodiments of the transparent substrate of the optical film B include the same ones as the transparent substrate of the optical film A.

(Radiant heat reflection layer)
Generally, “radiant heat” means heat carried by electromagnetic waves. In the present specification, the term “radiant heat reflection layer” refers to a layer having an average spectral reflectance of 5% or more at a wavelength of 2000 to 2500 nm.
The radiant heat reflection layer preferably has an average spectral reflectance at a wavelength of 2000 to 2500 nm of 5% or more, more preferably 10% or more. If the average of the spectral reflectances at wavelengths of 2000 to 2500 nm is too high, the transmittance of visible light on the long wavelength side tends to decrease. For this reason, it is preferable that the average of the spectral reflectance at a wavelength of 2000 to 2500 nm is 30% or less.
In the present specification, the average of the spectral reflectance at a wavelength of 2000 to 2500 nm is obtained by measuring the wavelength range of 2000 to 2500 nm at intervals of 5 nm.

The radiant heat reflecting layer preferably contains a metal or a metal oxide having a high reflectance in a wavelength region of 2,000 to 2,500 nm. Such metals or metal oxides include gold, silver and ITO (indium tin oxide). Further, it is preferable that the metal or the metal oxide having a high reflectance in the wavelength region of 2,000 to 2,500 nm is in the form of nanowires or fine particles from the viewpoint of transparency.
Preferred embodiments of the metal or metal oxide having high reflectivity in the wavelength region of 2,000 to 2,500 nm include silver nanowires, ITO particles, Ag particles, Au particles, and the like.

When the radiation heat reflection layer includes silver nanowires, the radiation heat reflection layer is preferably a silver nanowire layer in which adjacent silver nanowires are dispersed in a transparent resin such that adjacent silver nanowires have contact points.
The average diameter of the silver nanowire is preferably 200 nm or less. By setting the average diameter of the silver nanowire to 200 nm or less, an increase in haze can be suppressed. The average diameter of the silver nanowires is more preferably 10 nm or more and 180 nm or less.
The length of the silver nanowire is preferably 500 μm or less from the viewpoint of visible light transmission. The length of the silver nanowire is more preferably 1 μm or more and 300 μm or less, further preferably 10 μm or more and 30 μm or less.
The diameter and the length of the silver nanowire can be calculated by the same method as the diameter and the length of the metal nanowire included in the heat conductive layer described above.

The silver nanowire layer may contain other components such as a cover resin in addition to the silver nanowire.
The cover resin can serve as the transparent resin described above. As the cover resin, the same resin as the cover resin exemplified for the heat conductive layer can be used.
The total thickness of the silver nanowire layer is preferably from 10 nm to less than 300 nm, more preferably from 50 nm to 200 nm.

  When the radiant heat reflection layer includes one or more particles selected from ITO particles, Ag particles, and Au particles (hereinafter, may be referred to as “radiation heat reflection particles”), the radiant heat reflection layer is formed of a transparent resin in the transparent resin. Preferably, the radiation heat reflecting particles are densely packed. Specifically, 100 to 1500 parts by mass of the radiant heat reflecting particles are preferably contained, more preferably 200 to 1300 parts by mass, and even more preferably 500 to 1200 parts by mass, based on 100 parts by mass of the transparent resin. .

The average particle diameter of the radiant heat reflecting particles is preferably from 5 nm to 200 nm, more preferably from 5 nm to 100 nm, even more preferably from 10 nm to 80 nm.
In the present specification, the average particle diameter of various particles can be calculated by the following operations (1) to (3).
(1) An image of a cross section of a molded article containing particles is taken by TEM or STEM. It is preferable that the acceleration voltage of the TEM or STEM is 10 kv to 30 kV, and the magnification is 50,000 to 300,000.
(2) Ten arbitrary particles are extracted from the observation image, and the particle diameter of each particle is calculated. The particle diameter is measured as a distance between straight lines in a combination of two straight lines that maximizes the distance between the two straight lines when the cross section of the particle is sandwiched between any two parallel straight lines.
(3) The same operation is performed five times on an observation image of another screen of the same sample, and a value obtained from a number average of a total of 50 particles is defined as an average particle diameter of the particles.

  When the heat radiation reflection layer contains the radiation reflection particles, the thickness is not particularly limited, and is usually 0.1 to 5.0 μm, preferably 0.3 to 2.0 μm.

(Functional layer)
The optical film B may further have a functional layer such as an antiglare layer, an antireflection layer, an antistatic layer, a refractive index adjusting layer, a hard coat layer, an antifouling layer, and a circularly polarizing plate. The position of the functional layer with respect to the radiant heat reflecting layer in the display device may be appropriately determined according to the type of the functional layer.

  As described below, in the display device of the embodiment B, it is preferable that the optical film B (the optical film including the radiation heat reflection layer) is disposed on the outermost surface of the display device. For this reason, the optical film B preferably has an antireflection layer as a functional layer. Further, the position of the antireflection layer relative to the radiation heat reflection layer in the display device is preferably closer to the surface than the radiation heat reflection layer.

  When the optical film B has a hard coat layer, the position is preferably between the transparent substrate and the radiation heat reflection layer.

(Hard coat layer)
The hard coat layer, which is an example of the functional layer, preferably contains a cured product of a curable resin composition such as a thermosetting resin composition or an ionizing radiation-curable resin composition from the viewpoint of abrasion resistance. More preferably, the composition contains a cured product of the curable resin composition.

  The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that is cured by heating. Examples of the thermosetting resin include acrylic resin, urethane resin, phenol resin, urea melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin. In the thermosetting resin composition, a curing agent is added to these curable resins as necessary.

The ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter, also referred to as “ionizing radiation-curable compound”). Examples of the ionizing radiation-curable functional group include an ethylenically unsaturated bond group such as a (meth) acryloyl group, a vinyl group and an allyl group, and an epoxy group and an oxetanyl group. As the ionizing radiation-curable compound, a compound having an ethylenically unsaturated bond group is preferable, a compound having two or more ethylenically unsaturated bond groups is more preferable, and among them, a compound having two or more ethylenically unsaturated bond groups ( (Meth) acrylate compounds are more preferred. As the (meth) acrylate-based compound having two or more ethylenically unsaturated bonding groups, any of a monomer and an oligomer can be used.
In addition, ionizing radiation means, among electromagnetic waves or charged particle beams, those having energy quanta capable of polymerizing or cross-linking molecules. Usually, ultraviolet (UV) or electron beam (EB) is used. Electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.
In the present specification, (meth) acrylate means acrylate or methacrylate, (meth) acrylic acid means acrylic acid or methacrylic acid, and (meth) acryloyl group means acryloyl group or methacryloyl group. means.

  The thickness of the hard coat layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 1.0 μm or more, and still more preferably 2.0 μm or more from the viewpoint of abrasion resistance. In addition, the thickness of the hard coat layer is preferably 100 μm or less, more preferably 50 μm or less, more preferably 30 μm or less, more preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, from the viewpoint of curling suppression.

(Anti-reflective layer)
Examples of the antireflection layer include a single-layer structure of a low-refractive-index layer and a laminated structure of a high-refractive-index layer and a low-refractive-index layer. When the radiant heat reflecting layer contains radiant heat reflecting particles, the radiant heat reflecting layer is preferable in that it can also serve as a high refractive index layer.

The refractive index of the low refractive index layer is preferably 1.10 to 1.48, more preferably 1.20 to 1.45, more preferably 1.26 to 1.40, and more preferably 1.28 to 1.38. Preferably, 1.30 to 1.32 is more preferable.
Further, the thickness of the low refractive index layer is preferably from 80 to 120 nm, more preferably from 85 to 110 nm, and even more preferably from 90 to 105 nm. Further, the thickness of the low refractive index layer is preferably larger than the average particle diameter of low refractive index particles such as hollow particles.

The method of forming the low refractive index layer can be roughly classified into a wet method and a dry method. Examples of the wet method include a method of forming by a sol-gel method using a metal alkoxide or the like, a method of forming by coating a resin having a low refractive index such as a fluororesin, and a method of forming a resin composition containing low refractive index particles. A method of applying and forming a coating liquid for forming a refractive index layer may be used. Examples of the dry method include a method of selecting particles having a desired refractive index from low refractive index particles and forming the particles by a physical vapor deposition method or a chemical vapor deposition method.
The wet method is superior to the dry method in terms of production efficiency, suppression of oblique reflection hue, and chemical resistance. In the present embodiment, even in the wet method, from the viewpoint of adhesion, water resistance, scratch resistance and low refractive index, a coating liquid for forming a low refractive index layer containing low refractive index particles in a binder resin composition. It is preferable to form with. As the binder resin composition, for example, the curable resin composition exemplified for the hard coat layer can be used.

The low refractive index particles preferably include at least one selected from hollow particles and non-hollow particles. From the viewpoint of the balance between low reflection and scratch resistance, it is preferable to use one or more selected from hollow particles and one or more selected from non-hollow particles in combination.
The material of the hollow particles and the non-hollow particles may be any of an inorganic compound and an organic compound such as silica and magnesium fluoride, but silica is preferred from the viewpoint of lowering the refractive index and strength.

  In consideration of optical properties and mechanical strength, the average particle diameter of the hollow silica particles is preferably from 50 nm to 100 nm, more preferably from 60 nm to 80 nm. Further, in consideration of dispersibility while preventing aggregation of the non-hollow silica particles, the average particle diameter of the non-hollow silica particles is preferably 5 nm or more and 20 nm or less, more preferably 10 nm or more and 15 nm or less.

As the content of the hollow silica particles increases, the filling rate of the hollow silica particles in the binder resin increases, and the refractive index of the low refractive index layer decreases. Therefore, the content of the hollow silica particles is preferably at least 100 parts by mass, more preferably at least 150 parts by mass, based on 100 parts by mass of the binder resin.
On the other hand, if the content of the hollow silica particles with respect to the binder resin is too large, the number of hollow silica particles exposed from the binder resin increases, and the amount of the binder resin binding between the particles decreases. For this reason, the hollow silica particles are likely to be damaged or fall off, and the mechanical strength such as scratch resistance of the low refractive index layer tends to decrease. For this reason, the content of the hollow silica particles is preferably 400 parts by mass or less, more preferably 300 parts by mass or less, based on 100 parts by mass of the binder resin.

When the content of the non-hollow silica particles is small, even if the non-hollow silica particles are present on the surface of the low refractive index layer, the increase in hardness may not be affected. In addition, when the non-hollow silica particles are contained in a large amount, the influence of uneven shrinkage due to the polymerization of the binder resin can be reduced, and the unevenness generated on the surface of the low refractive index layer after the resin is cured can be reduced. Therefore, the content of the non-hollow silica particles is preferably at least 90 parts by mass, more preferably at least 100 parts by mass, per 100 parts by mass of the binder resin.
On the other hand, if the content of the non-hollow silica particles is too large, the non-hollow silica tends to aggregate, causing uneven shrinkage of the binder resin, and increasing the surface irregularities. Therefore, the content of the non-hollow silica particles is preferably 200 parts by mass or less, more preferably 150 parts by mass or less based on 100 parts by mass of the binder resin.

By including the hollow silica particles and the non-hollow silica particles in the binder resin at the above ratio, the barrier properties of the low refractive index layer can be improved. This is presumed to be because the permeation of gas and the like is hindered by the silica particles being uniformly dispersed at a high filling rate.
In addition, various cosmetics such as sunscreens and hand creams may contain low-volatile low molecular weight polymers. By improving the barrier properties of the low-refractive-index layer, it is possible to prevent the low-molecular polymer from penetrating into the coating film of the low-refractive-index layer, and to cause a problem (for example, appearance Abnormality).

The high refractive index layer preferably has a refractive index of 1.53 to 1.85, more preferably 1.54 to 1.80, more preferably 1.55 to 1.75, and more preferably 1.56 to 1.70. preferable.
The thickness of the high refractive index layer is preferably 200 nm or less, more preferably 50 to 180 nm, and even more preferably 70 to 150 nm.

  The high refractive index layer can be formed, for example, from a coating liquid for forming a high refractive index layer containing a binder resin composition and high refractive index particles. As the binder resin composition, for example, the curable resin composition exemplified for the hard coat layer can be used.

  Examples of the high refractive index particles include antimony pentoxide (1.79), zinc oxide (1.90), titanium oxide (2.3 to 2.7), cerium oxide (1.95), and tin-doped indium oxide (1. 95 to 2.00), antimony-doped tin oxide (1.75 to 1.85), yttrium oxide (1.87), and zirconium oxide (2.10).

  The average particle diameter of the high refractive index particles is preferably 2 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more. In addition, the average particle diameter of the high refractive index particles is preferably 200 nm or less, more preferably 100 nm or less, more preferably 80 nm or less, more preferably 60 nm or less, and more preferably 30 nm or less, from the viewpoint of suppression of whitening and transparency. The smaller the average particle diameter of the high refractive index particles, the better the transparency. In particular, by setting the average particle diameter to 60 nm or less, the transparency can be made extremely good.

(optical properties)
The optical film B preferably has a total light transmittance of 70% or more, more preferably 80% or more, even more preferably 90% or more according to JIS K7361-1: 1997.
Further, the optical film B preferably has a haze of JIS K7136: 2000 of 5% or less, more preferably 3% or less, further preferably 1% or less.

(Position of optical film B)
In the display device of Embodiment B, it is preferable that an optical film (optical film B) including a radiation heat reflecting layer is disposed on the outermost surface of the display device. With this configuration, the radiant heat generated from the light emitting surface side of the display element can be dispersed over a relatively wide range without being concentrated on a narrow range, and the radiant heat can be radiated into the display device from outside the display device. Can be suppressed from entering, so that the optical film B can be easily suppressed from being deformed due to a high temperature.
For this reason, by disposing the optical film B as described above, a display element (for example, a self-luminous organic EL display element, a micro LED display element, a diagonal 50 inch) that generates a large amount of heat from the light emitting surface side. The display device having the above-described large display element) can easily exert the effects of the present invention.

In the embodiment B, in the display device, the total thickness of the layer located on the side opposite to the display element with respect to the radiation heat reflecting layer is preferably 350 nm or less, more preferably 300 nm or less, and more preferably 270 nm or less. It is more preferred that there be.
The temperature of the layer located on the side opposite to the display element with respect to the radiant heat reflective layer increases due to radiant heat outside the display device and radiant heat generated from the display element and transmitted through the radiant heat reflective layer. Then, the degree of temperature rise tends to increase as the total thickness of the layer increases. For this reason, by setting the total thickness of the layer located on the side opposite to the display element with respect to the radiation heat reflecting layer to the above range, it is possible to easily suppress the optical film B from becoming high in temperature.
The layer located on the side opposite to the display element with respect to the radiant heat reflecting layer is a layer included in the optical film B (19) itself as in the functional layer 18 in FIG. Layer included in the member.

When the optical film B has a low refractive index layer on the side opposite to the display element with respect to the radiant heat reflecting layer, the total thickness is preferably from 50 to 200 nm, more preferably from 80 to 150 nm.
When the optical film B has a high-refractive-index layer and a low-refractive-index layer on the side opposite to the display element with respect to the radiant heat reflecting layer, the total thickness is preferably 80 to 300 nm, and 130 to 250 nm. Is more preferred.

(Display element)
Examples of the display element used in the embodiment B include a liquid crystal display element, an organic EL display element, and a micro light emitting diode display element (micro LED display element). Examples of the liquid crystal display element include an IPS (In Plane Switching) mode liquid crystal display element and an FFS (Fringe Field Switching) mode liquid crystal display element. As the organic EL display element, for example, a translucent first electrode ( An anode, an organic light-emitting layer including a light-emitting layer, and a second electrode (cathode) are sequentially stacked on the surface of a light-transmitting substrate.

In an organic EL display element, an organic light emitting layer between both electrodes emits light by applying a current between a cathode and an anode. At this time, energy that does not contribute to light emission is generated as heat, and the inside of the display device may become hot. In particular, in the case of an RGB separation method in which a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer are planarly arranged as light-emitting layers of an organic EL display element, the energy required for light emission differs for each color. As a result, the heat generated differs, so that a high-temperature region and a low-temperature region are generated in the display screen, and heat unevenness may occur (especially, when a still image is displayed, the heat unevenness tends to be remarkable). Therefore, when the display element is an organic EL display element, the effects of the present invention can be more remarkably exhibited.
In addition, since the micro LED display element displays an image using a large number of LED chips, the temperature is inevitably high. Therefore, when the display element is a micro LED display element, the effects of the present invention can be more remarkably exhibited.
In addition, even when the display element is a large display element having a diagonal size of 50 inches or more, the temperature inside the display element is likely to be high, so that the effects of the present invention can be more remarkably exhibited.
Further, regardless of the type and size of the display element, when the display device of the embodiment B is mounted on a vehicle, the effects of the present invention can be more remarkably exhibited.

  The display device of Embodiment B preferably has a general-purpose heat radiation mechanism on the side opposite to the light emitting surface of the display element from the viewpoint of more easily exhibiting the effects of the present invention. The general-purpose heat radiation mechanism includes an air cooling fan, a heat radiation fin, a heat pump, a Peltier device, and the like.

<Embodiment C>
The display device according to the embodiment C of the present invention includes a display element, an optical film including a heat conductive layer disposed on the light emitting surface side of the display element, and a heat radiation thermally grounded from a peripheral portion of the heat conductive layer. And an optical film including a radiant heat reflection layer on the light exit surface side of the optical film including the heat conductive layer.

  In the embodiment C, the “optical film including the heat conductive layer disposed on the light emitting surface side of the display element” and the “heat radiating member thermally grounded from the periphery of the heat conductive layer” are the same as those in the embodiment A. One. In the embodiment C, the “optical film including the radiation heat reflection layer” includes the same as in the embodiment B. In the embodiment C, the “display element” is the same as that in the embodiment A or B.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited to the embodiments described in the embodiments.

<Embodiment A>
[Example A1]
(1) Preparation of Optical Film A (1-1) Formation of Hard Coat Layer A biaxially stretched polyethylene terephthalate (PET) film (thickness: 100 μm, area: 552 mm × 959 mm) was prepared as a transparent substrate. On one surface of the transparent substrate, a composition for forming a hard coat layer shown below was applied at an application speed of 10 m / min to form a coating film. The coating was dried at 90 ° C. for 60 seconds to remove the solvent. Next, the coating film was irradiated with ultraviolet light at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film, thereby forming a hard coat (HC) layer having a thickness of 5 μm after curing.

(Composition for forming hard coat layer)
The following components were mixed to prepare a composition for forming a hard coat layer.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 46 parts by mass-Photopolymerization initiator (Ciba Japan Co., Ltd., Irgacure 184): 4 parts by mass-Methyl ethyl ketone: 50 parts by mass

(1-2) Formation of Thermal Conductive Layer Next, a copper foil (thickness: 10 μm) is bonded via an adhesive on the surface of the transparent substrate opposite to the surface on which the hard coat layer is formed. Then, a mesh-like pattern was formed by etching using a photolithography method, and an optical film A was obtained.
The surface resistance value of the heat conductive layer of the obtained optical film A was measured by a four-terminal method using “Loresta-EP MCP-T360 manufactured by Mitsubishi Chemical Corporation”, and was 4.2 × 10 ⁻² Ω /. It was □.
In addition, a conductive wire is fixed to one portion of the peripheral portion of the surface of the heat conductive layer using a silver paste, and further, the conductive wire is connected to a heat dissipating member (Nichrome, volume resistance value 1.5 × 10 ⁻⁶ Ωm), and a thermal ground is connected. Processing was performed. The area of the fixed portion was 2 mm ² .

(2) Manufacture of display device The original optical sheet and the glass plate, which were bonded to a commercially available organic EL display device of a separate RGB coating method (trade name: XEL-1, manufactured by Sony Corporation), were peeled off. Then, the optical film A and the glass plate obtained above were assembled, and each member was sandwiched to produce a display device.

  The display screen after the still image was displayed on the display screen of the obtained display device for 12 hours was visually observed. As a result, there was no unevenness in brightness and color due to the deformation of the optical film A in the display screen, and there was no bending discomfort in the reflected image, and the visibility was good.

[Example A2]
(1) Preparation of Coating Solution (1-1) Preparation of Silver Nanowire-Containing Composition Ethylene glycol (EG) as a reducing agent, and polyvinylpyrrolidone (PVP: average molecular weight 1.3 million, Aldrich Co., Ltd.) as a form control agent and protective colloid agent Was used to separate the nucleation step and the particle growth step shown below to form particles, thereby preparing a silver nanowire-containing composition.

<Nucleation step>
While stirring 100 mL of the EG solution maintained at 160 ° C. in the reaction vessel, 2.0 mL of an EG solution of silver nitrate (silver nitrate concentration: 1.0 mol / L) was added at a constant flow rate over 1 minute. Thereafter, silver ions were reduced while maintaining the temperature at 160 ° C. for 10 minutes to form silver core particles. The reaction liquid was yellow due to the surface plasmon absorption of the nano-sized silver fine particles, confirming that silver ions were reduced to form silver fine particles (nuclear particles). Subsequently, 10.0 mL of an EG solution of PVP (PVP concentration: 3.0 × 10 ⁻¹ mol / L) was added at a constant flow rate over 10 minutes.

<Particle growth process>
The reaction solution containing the core particles after completion of the nucleation step is maintained at 160 ° C. while stirring, and 100 mL of an EG solution of silver nitrate (silver nitrate concentration: 1.0 × 10 ⁻¹ mol / L) and PVP 100 mL of an EG solution (PVP concentration: 3.0 × 10 ⁻¹ mol / L) was added at a constant flow rate over 120 minutes using a double jet method. In this particle growth step, when the reaction solution was collected every 30 minutes and confirmed by an electron microscope, the nucleus particles formed in the nucleation step grew into a wire-like form with the passage of time. No new fine particles were generated in the process. When the diameter and length of the finally obtained silver nanowire were measured, the diameter of the silver nanowire was 30 nm and the length was 15 μm. The diameter of the silver nanowire was determined by using a transmission electron microscope (TEM), measuring the diameter of 50 conductive fibers at a magnification of 1000 to 500,000, and calculating the average value of the diameters of the 50 conductive fibers. . The length of the silver nanowire was measured using a scanning electron microscope (SEM) at a magnification of 1,000 to 500,000 times, and the length of the 50 conductive fibers was measured. The average value was obtained.

<Desalting water washing process>
After the reaction solution after the particle growth step was cooled to room temperature, the reaction solution was subjected to a desalting water washing treatment using an ultrafiltration membrane having a molecular weight cutoff of 0.2 μm, and the solvent was replaced with ethanol. Then, the liquid volume was concentrated to 100 mL to obtain a silver nanowire dispersion. Finally, the mixture was diluted with ethanol and anone such that the silver nanowire concentration was 0.1% by mass and the solvent ratio of the diluted anone was 30% by mass, to obtain a silver nanowire-containing composition.

(1-2) Preparation of composition for cover resin Each component was blended so as to have the composition shown below to obtain a composition for cover resin.
<Composition for cover resin>
-Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (product name "KAYARAD PET-30", manufactured by Nippon Kayaku): 5 parts by mass-Polymerization initiator (product name "Irgacure 184", manufactured by BASF Japan) : 0.25 parts by mass, methyl ethyl ketone: 70 parts by mass, cyclohexanone: 24.75 parts by mass

(2) Preparation of Optical Film A (2-1) Formation of Hard Coat Layer As a transparent substrate, a biaxially stretched polyethylene terephthalate (PET) film (thickness: 100 μm, area: 552 mm × 959 mm) was prepared. On one surface of the transparent substrate, a composition for forming a hard coat layer shown below was applied at an application speed of 10 m / min to form a coating film. The coating was dried at 90 ° C. for 60 seconds to remove the solvent. Next, the coating film was irradiated with ultraviolet light at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film, thereby forming a hard coat (HC) layer having a thickness of 5 μm after curing.

(Composition for forming hard coat layer)
The following components were mixed to prepare a composition for forming a hard coat layer.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 46 parts by mass-Photopolymerization initiator (Ciba Japan Co., Ltd., Irgacure 184): 4 parts by mass-Methyl ethyl ketone: 50 parts by mass

(2-2) Formation of Thermal Conductive Layer Next, the amount of the silver nanowire-containing composition deposited on the surface of the transparent substrate opposite to the surface on which the hard coat layer is formed is 10 mg / m ^2. Directly. Then, after flowing dry air at 50 ° C. at a flow rate of 0.5 m / s for 15 seconds through the applied silver nanowire-containing composition, dry air at 70 ° C. is further flowed at a flow rate of 10 m / s for 30 seconds. The silver nanowire was directly arranged on the PET film by evaporating the dispersion medium in the silver nanowire-containing composition.
Next, the composition for a cover resin was applied so as to cover the silver nanowires to form a coating film. Then, after flowing dry air at 50 ° C. at a flow rate of 0.5 m / s for 15 seconds through the formed coating film, dry air at 70 ° C. is further passed at a flow rate of 10 m / s for 30 seconds to dry. Then, the solvent in the coating film was evaporated, and the coating film was cured by irradiating ultraviolet rays so that the integrated light amount became 100 mJ / cm ² , thereby forming a cover resin having a thickness of 100 nm.
As described above, a heat conductive layer (silver nanowire layer) was formed, and an optical film A was obtained.

The surface resistance of the heat conductive layer of the obtained optical film A was 51 Ω / □ as measured by a four-terminal method using “Loresta-EP MCP-T360” manufactured by Mitsubishi Chemical Corporation.
In addition, a conductive wire is fixed to one portion of the peripheral portion of the surface of the heat conductive layer using a silver paste, and further, the conductive wire is connected to a heat dissipating member (Nichrome, volume resistance value 1.5 × 10 ⁻⁶ Ωm), and a thermal ground is connected. Processing was performed. The area of the fixed portion was 2 mm ² .

(3) Production of display device The original optical sheet and the glass plate that had been bonded to a commercially available organic EL display device of a separately applied RGB type (trade name: XEL-1, manufactured by Sony Corporation) were peeled off, and instead, Then, the optical film A and the glass plate obtained above were assembled, and each member was sandwiched to produce a display device.

  The display screen after the still image was displayed on the display screen of the obtained display device for 12 hours was visually observed. As a result, there was no unevenness in brightness and color due to the deformation of the optical film A in the display screen, and there was no bending discomfort in the reflected image, and the visibility was good.

[Comparative Example A1]
(1) Preparation of Optical Film A biaxially stretched polyethylene terephthalate (PET) film (thickness: 100 μm, area: 552 mm × 959 mm) was prepared as a transparent substrate. On one surface of the transparent substrate, a composition for forming a hard coat layer shown below was applied at an application speed of 10 m / min to form a coating film. The coating was dried at 90 ° C. for 60 seconds to remove the solvent. Next, the coating film is irradiated with ultraviolet light at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film and obtain an optical film having a hard coat (HC) layer having a thickness of 5 μm after curing. Was.

(Composition for forming hard coat layer)
The following components were mixed to prepare a composition for forming a hard coat layer.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 46 parts by mass-Photopolymerization initiator (Ciba Japan Co., Ltd., Irgacure 184): 4 parts by mass-Methyl ethyl ketone: 50 parts by mass

(2) Manufacture of display device The original optical sheet and the glass plate, which were bonded to a commercially available organic EL display device of a separate RGB coating method (trade name: XEL-1, manufactured by Sony Corporation), were peeled off. Then, the optical film and the glass plate obtained above were assembled, and each member was sandwiched to produce a display device.

  The display screen after the still image was displayed on the display screen of the obtained display device for 12 hours was visually observed. As a result, there was a portion in the display screen where the brightness and color were uneven due to the deformation of the optical film, and the reflection image was found to have a strange feeling of bending.

[Comparative Example A2]
(1) Production of Optical Film (1-1) Formation of Hard Coat Layer As a transparent substrate, a biaxially stretched polyethylene terephthalate (PET) film (thickness: 100 μm, area: 552 mm × 959 mm) was prepared. On one surface of the transparent substrate, a composition for forming a hard coat layer shown below was applied at an application speed of 10 m / min to form a coating film. The coating was dried at 90 ° C. for 60 seconds to remove the solvent. Next, the coating film is irradiated with ultraviolet light at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film and obtain an optical film having a hard coat (HC) layer having a thickness of 5 μm after curing. Was.

(Composition for forming hard coat layer)
The following components were mixed to prepare a composition for forming a hard coat layer.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 46 parts by mass-Photopolymerization initiator (Ciba Japan Co., Ltd., Irgacure 184): 4 parts by mass-Methyl ethyl ketone: 50 parts by mass

(1-2) Formation of Transparent Conductive Layer Next, while introducing argon mixed with 5% by volume of oxygen gas, a pressure of 0.15 Pa was used using an ITO target [indium: tin = 90: 10 (mass ratio)]. Under the conditions of a frequency of 100 kHz, a power density of 0.64 w / cm ² , and a reversal pulse width of 1 μsec, pulse sputtering is performed, and the thickness of the transparent substrate on the surface opposite to the surface on which the hard coat layer is formed is formed. An optical film was obtained by forming a 5 nm ITO film.

(2) Manufacture of display device The original optical sheet and the glass plate, which were bonded to a commercially available organic EL display device of a separate RGB coating method (trade name: XEL-1, manufactured by Sony Corporation), were peeled off. Then, the optical film and the glass plate obtained above were assembled, and each member was sandwiched to produce a display device.

  The display screen after the still image was displayed on the display screen of the obtained display device for 12 hours was visually observed. As a result, there was a portion in the display screen where the brightness and color were uneven due to the deformation of the optical film, and the reflection image was found to have a strange feeling of bending.

(Summary of results)
In Examples A1 and A2 having the optical film A having the heat conductive layer and having the heat radiating member thermally grounded from the periphery of the heat conductive layer of the optical film A, the visual recognition after displaying the still image for a long time was performed. It had excellent properties. When a biaxially stretched polyethylene terephthalate (PET) film having a retardation value of 3000 nm or more was used as the transparent substrate, the visibility was good at any angle, and the lens was compatible with polarized sunglasses.

<Embodiment B>
(I) Preparation of optical film [Example B1]
A triacetyl cellulose film (thickness: 80 μm, area: 225 mm × 150 mm) was prepared as a transparent substrate.
On one surface of the transparent substrate, a silver nanowire-containing composition was applied in the same manner as in Example A2, and after attaching the silver nanowires on a triacetyl cellulose film, a cover resin composition was further applied. After drying and curing, a cover resin having a thickness of 100 nm was formed.
As described above, the optical film B used in Example B1 having the radiant heat reflection layer (silver nanowire layer) on the transparent substrate was obtained.

[Example B2]
A triacetyl cellulose film (thickness: 80 μm, area: 225 mm × 150 mm) was prepared as a transparent substrate.
On one surface of the transparent substrate, a composition for forming a radiation heat reflection layer having the following formulation was applied, dried and cured to form a radiation heat reflection layer containing 700-nm-thick ITO particles.
As described above, the optical film B used in Example B2, having the radiant heat reflection layer (the layer containing the ITO particles) on the transparent substrate, was obtained.

(Composition for forming radiation heat reflection layer)
The following components were mixed to prepare a radiation heat reflecting layer forming composition.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 2 parts by mass-ITO particles (average particle size: 30 nm): 10 parts by mass-Photopolymerization initiator (manufactured by Ciba Japan Co., Ltd.) Irgacure 184): 2 parts by mass / methyl isobutyl ketone: 88 parts by mass

[Comparative Example B1]
As an optical film used in Comparative Example B1, a triacetyl cellulose film (thickness: 80 μm, area: 225 mm × 150 mm) was prepared.

[Comparative Example B2]
A triacetyl cellulose film (thickness: 80 μm, area: 225 mm × 150 mm) was prepared as a transparent substrate.
On one surface of the transparent substrate, a composition for forming a heat conductive layer having the following formulation was applied, dried and cured to form a heat conductive layer containing aluminum nitride particles having a thickness of 700 nm.
As described above, an optical film used in Comparative Example B2, having a heat conductive layer (a layer containing aluminum nitride particles) on a transparent substrate, was obtained.

(The composition for forming a heat conductive layer of Comparative Example B2)
The following components were mixed to prepare a composition for forming a heat conductive layer.
-Pentaerythritol triacrylate (KAYARAD PET-30, manufactured by Nippon Kayaku Co., Ltd.): 2 parts by mass-Aluminum nitride particles (average particle size: 1.5 m): 10 parts by mass-Photopolymerization initiator (Ciba Japan Co., Ltd.) ), Irgacure 184): 2 parts by mass, methyl isobutyl ketone: 88 parts by mass

[Comparative Example B3]
A triacetyl cellulose film (thickness: 80 μm, area: 225 mm × 150 mm) was prepared as a transparent substrate.
On one surface of the transparent substrate, a composition for forming a heat conductive layer having the following formulation was applied, dried and cured to form a heat conductive layer containing 150 nm-thick boron nitride particles.
As described above, an optical film used in Comparative Example B3, having a heat conductive layer (a layer containing boron nitride particles) on a transparent substrate, was obtained.

(Composition for forming a heat conductive layer of Comparative Example B3)
The following components were mixed to prepare a composition for forming a heat conductive layer.
-Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD PET-30): 2 parts by mass-Boron nitride particles (average particle size 200 nm): 10 parts by mass-Photopolymerization initiator (manufactured by Ciba Japan Co., Ltd.) , Irgacure 184): 2 parts by mass. Methyl ethyl ketone: 88 parts by mass.

(II) Preparation of Display Device The optical film of Example B1 was placed on a commercially available liquid crystal display device (manufactured by Amazon, Inc., trade name: Kindle Fire HDX) so that the transparent substrate side of the optical film of Example B1 was facing the display device side. A liquid crystal display device of B1 was obtained.
Similarly, the transparent substrate side of the optical film of the optical film for Example B2 and Comparative Examples B1 to B3 is directed to the display device side on a commercially available liquid crystal display device (manufactured by Amazon, Inc., trade name: Kindle Fire HDX). The liquid crystal display devices of Example B2 and Comparative Examples B1 to B3 were obtained.

(III) Heat Endurance Test The following heat endurance test was performed assuming the inside of a car in summer.
<Temperature>
The liquid crystal display devices of Examples B1 to B2 and Comparative Examples B1 to B3 prepared in the above (II) were placed in an oven at 80 ° C., and after 10 minutes had passed, an IR camera (FLIR E4, manufactured by FLIR Systems Co., Ltd.) was used. ), The temperature was measured from the surface side (the distance between the optical film and the IR camera was 30 cm). Table 1 shows the maximum temperatures on the optical film. A maximum temperature of 70 ° C. or less is a pass level.
<Visibility>
The liquid crystal display devices of Examples B1 and B2 and Comparative Examples B1 and B3 prepared in the above (II) were placed in an oven at 80 ° C., and were taken out after elapse of 10 minutes. Immediately after being taken out, the screen of the liquid crystal display device (a screen of solid green color) is displayed, and it is visually determined whether or not there is any unevenness in brightness and color due to deformation of the optical film in the display screen. evaluated. As a result, "A" was assigned when there was no portion with uneven brightness and color, and "C" was assigned when there was a portion with uneven brightness and color.

(IV) Total light transmittance The total light transmittance of the optical films for Examples B1 and B2 and Comparative Examples B1 and B3 prepared in the above (I) was measured. The measuring device used was a haze meter (HM-150, manufactured by Murakami Color Research Laboratory), and the light incident surface was on the transparent substrate side.

  From the results in Table 1, it can be confirmed that the display devices of Examples B1 and B2 can suppress the temperature rise of the optical film in the heat durability test, and can suppress the decrease in visibility due to the deformation of the optical film.

  The display device of the present invention includes, for example, OA equipment such as a personal computer monitor, a notebook personal computer, and a copy machine, portable equipment such as a mobile phone, a clock, and a personal digital assistant (PDA), and home electric appliances such as a video camera, a television, and a microwave. It is suitably used as a device, a back monitor, a monitor for a car navigation system, a car audio device, or the like.

1: display device 10: display element 11: transparent base material 12: heat conductive layer 121: transparent heat conductive area 122: grounding area 13: optical film A
14: peripheral portion 15: conducting wire 16: heat dissipating member 17: radiation heat reflecting layer 18: functional layer 19: optical film B
20: Other optical films

Claims (11)

A display element;
An optical film including a heat conductive layer, which is arranged on the light emitting surface side of the display element,
A heat dissipating member thermally grounded from a peripheral portion of the heat conductive layer,
A display device having:   2. The heat conductive layer according to claim 1, wherein the heat conductive layer is a metal nanowire layer dispersed in a transparent resin such that adjacent metal nanowires have contact points, or a layer formed in a mesh shape with a metal material, 2. Display device.   The display device according to claim 2, wherein the metal nanowire is a silver nanowire.   The display device according to claim 1, wherein a surface resistivity of the heat conductive layer is 250 Ω / □ or less.   The display device according to claim 1, wherein the display element is an organic EL display element.   The display device according to any one of claims 1 to 5, which is mounted on a vehicle.   The display device according to claim 1, wherein the display element and the optical film including the heat conductive layer are in contact with each other directly or via an adhesive layer. A display element;
An optical film including a radiant heat reflection layer, which is arranged on the light exit surface side of the display element,
A display device having:   The display device according to claim 8, wherein the radiant heat reflection layer is a silver nanowire layer dispersed in a transparent resin such that adjacent silver nanowires have contact points.   The display device according to claim 8, wherein the optical film including the radiation heat reflection layer is disposed on the outermost surface of the display device.   The display device according to any one of claims 8 to 10, wherein a total thickness of a layer located on a side opposite to the display element with respect to the radiation heat reflection layer in the display device is 350 nm or less.