JP2015170696A - Light extraction film and organic el planar light source including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light extraction film capable of providing an organic EL panel with fire retardancy without damaging a brightness improvement effect.SOLUTION: The light extraction film includes: an uneven surface 62 and a smooth surface 61, which are both principal planes of the light extraction film; and a resin lens layer 6 of equal to or more than 10 μm in an average thickness. On an entire surface of the uneven surface 62, an inorganic fire-retardant layer 7 of equal to or less than 5 μm in an average thickness, being in contact with the light extraction film and a resin adhesive layer 8 being in contact with the smooth surface 61 are provided. When making a direction heading for the uneven surface 62 from the smooth surface 61 to be a light extraction direction, a position of the inorganic fire-retardant layer 7 at a recess apex in the light extraction direction of the uneven surface 62 is closer to the smooth surface 61 than a position of a projection apex in the light extraction direction of the uneven surface 62.

Description

  The present invention relates to a light extraction film and an organic EL planar light source including the same.

  An EL element is a semiconductor element that converts electrical energy into light energy. An EL element is a surface light emitting element that utilizes a phenomenon that emits light when an electric field is applied to a substance. Utilizing features such as a self-luminous type and being thin, it can be applied to flat light sources and display elements. It is illustrated. The EL element is formed as an element structure in which an inorganic EL layer or an organic EL layer is sandwiched between electrodes.

  The basic structure of the organic EL element as an example is a structure in which, for example, a transparent anode electrode made of indium tin oxide (ITO), an organic EL layer having a light emitting layer, and a reflective cathode electrode are laminated on a glass substrate. It is formed from. In such an organic EL element, light emitted from the organic EL layer is normally emitted in all directions centering on the light emitter, and is extracted to the outside via a transparent anode electrode and a glass substrate. Alternatively, the light is once reflected in the direction opposite to the light extraction direction, reflected by the reflective cathode electrode, and extracted to the outside via the organic EL layer, the transparent anode electrode, and the glass substrate.

  However, when the light generated inside the organic EL element passes through the boundary surface of each medium, if the refractive index of the medium on the incident side is larger than the refractive index on the output side, the light is incident at an angle larger than the critical angle. Repeats total reflection at the interface and is confined inside the device. As a result, the light generated inside the organic EL layer is not extracted to the outside and causes an apparent decrease in efficiency as an organic EL element. In general, most of the emitted light obtained from the light emitting layer of the organic EL element is confined inside the element by total reflection, and the light extraction efficiency used as effective emitted light is about 17% to 20%. It has been known.

  As described above, the problem is that the efficiency of taking out the light emitted inside the EL element is low. A typical method for improving the light extraction efficiency is to provide a concavo-convex layer on the light extraction side of the substrate, thereby suppressing total reflection of light at the substrate-atmosphere interface and changing the light emission angle. The effect of improving the take-out efficiency can be expected. For example, Patent Document 1 discloses a method of forming a microlens on the light extraction side of a substrate.

  Further, Patent Document 2 discloses a surface light emission including a total reflection reduction layer A having a large number of uneven portions in a planar shape in order to obtain a surface light emitting device having high brightness in the front direction and oblique direction and excellent light extraction efficiency. The refractive index adjusting layer B is in contact with the light extraction side of the total reflection reducing layer A, and the refractive index nA of the total reflection reducing layer A and the refractive index nB of the refractive index adjusting layer B are 1.0. By satisfying the condition of <nB <nA, it is disclosed that a surface light emitting device having excellent light extraction efficiency in the front direction and the oblique direction can be obtained.

JP 2003-059642 A JP 2011-181269 A

  The method described in Patent Document 1 or Non-Patent Document 2 aims to improve light extraction efficiency by condensing light in the front direction by a microlens formed on the light extraction side of the substrate. Therefore, although the improvement in luminance centered on the front direction is seen due to the effect of the microlens, the light extraction film including the microlens is relatively thick, and the organic EL panel is used in a space where flame retardancy is required. In some cases, there is room for further improvement so that flame retardancy can be imparted to the panel itself, and improvements are desired.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a light extraction film capable of imparting flame retardancy to an organic EL panel without impairing the luminance enhancement effect.

  As a result of intensive studies to solve the above problems, the present inventors have found that the following configuration can provide a light extraction film capable of imparting flame retardancy to an organic EL panel without impairing the brightness enhancement effect. The present invention has been completed.

  That is, the present invention is a light extraction film having a concave and convex surface and a smooth surface as both main surfaces and including a resin lens layer having an average thickness of 10 μm or more, and is 5 μm or less in contact with the entire surface of the concave and convex surface. The average thickness of the inorganic flame retardant layer and the resin adhesive layer in contact with the smooth surface, where the light extraction direction of the concave / convex surface is a vertex of the concave portion when the direction from the smooth surface toward the concave / convex surface is the light extraction direction. The light extraction film is characterized in that the position of the inorganic flame retardant layer is closer to the smooth surface than the position of the convex portion vertex in the light extraction direction of the uneven surface.

A said light extraction film having a 25 cm ² or more areas are the inorganic flame retardant layer to the entire range of 25 cm ² or more of the uneven surface of continuous form, and said resin lens layer in the range It is preferable to use a light extraction film in which the inorganic flame retardant layer is formed without exposing the uneven surface.

  The inorganic flame retardant layer is preferably a light extraction film made of inorganic silica.

Film thickness _{D A} of the inorganic flame retardant layer in the convex apex, the thickness of the inorganic flame retardant layer in the concave apex when a _{D B,} 0.01 at <DA / DB <1.0 It is preferable to use a certain takeout film.

  The inorganic flame retardant layer is preferably a light extraction film formed by a spin coater.

  The resin adhesive layer is preferably a light extraction film including a diffusing material inside the layer.

  Moreover, this invention is an organic EL planar light source provided with an organic EL element, a glass substrate, and the light extraction film of this invention, Comprising: The other side of this glass substrate in which the organic EL element is formed in the one surface It is related with an organic electroluminescent planar light source provided with this light extraction film because the resin adhesion layer adheres in contact with the surface.

  By this invention, the light extraction film which can provide a flame retardance to an organic electroluminescent panel can be provided, without impairing a brightness improvement effect.

It is a cross-sectional schematic diagram of the organic EL planar light source which concerns on one embodiment of this invention. It is explanatory drawing which inserted the line | wire for description etc. in the cross-sectional electron micrograph of the resin lens layer part of the test sample of Example 1. FIG. It is the photograph after the combustion test of the center part exposed to the flame of the test sample of Example 1. FIG. It is the photograph after the combustion test of the center part exposed to the flame of the test sample of the comparative example 1. It is a comparison figure of the angle dependence of the brightness | luminance of the test surface light source of the comparative example 2 and Example 2. FIG. It is a comparison figure for the angle dependence of the color temperature of the test surface light source of the comparative example 2 and Example 2. FIG. It is a comparison figure of the angle dependence of the brightness | luminance of the test surface light source before and behind application | coating of Example 5. FIG. It is a comparison figure for the angle dependence of the color temperature of the test surface light source before and after application | coating of Example 5. FIG. 4 is a cross-sectional electron micrograph of a resin lens layer portion of a test sample of Comparative Example 3. 6 is a cross-sectional electron micrograph of a resin lens layer portion of a test sample of Comparative Example 4.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

(Surface light source)
FIG. 1 illustrates a cross-sectional configuration of a planar light source 10 to which the light extraction film of the present invention is applied in the case of a bottom emission type organic EL planar light source. The organic EL planar light source 10 shown in FIG. 1 includes a planar light emitter 1, and light is emitted from the planar light emitter to the outside, that is, the side where light is emitted into the atmosphere, that is, the outermost layer on the light extraction side. The light extraction film 11 of the present invention is provided.

  As such a planar light emitter 1 according to the present invention, a known one can be used without any particular limitation. For example, an EL panel including an electroluminescent element that emits light by using electricity as energy can be used. The EL element includes an organic EL element and an inorganic EL element. Since the inorganic EL element needs to be driven at a high voltage, the organic EL element includes an organic EL element that can be driven at a low voltage from the viewpoint of energy saving. Can be preferably used.

  Here, the organic EL element includes a structure including two electrodes in contact with the organic EL layer, such as an anode electrode and a cathode electrode, in order to apply a voltage to the organic EL layer in order to emit light from the organic EL layer contained therein. Is the body.

  In order to protect the light emitting element contained in the light emitter, a planar light emitter including such a light emitting element such as an organic EL element generally has a light emitter protective layer 9 on the side opposite to the light extraction side. Prepare.

(Organic EL panel)
The substrate 2 serving as a support for the organic EL element is not particularly limited as long as it is transparent. For example, the substrate 2 is appropriately selected from a transparent substrate such as glass, a flexible film substrate, and a plastic substrate. Especially, a glass substrate is preferable from a viewpoint made into the planar light source excellent in the flame retardance.

  Thus, the most suitable planar light emitter for application of the light extraction film of the present invention is an organic EL panel in which a bottom emission type organic EL element is formed on a glass substrate. Such a preferable planar light source is an organic EL planar light source including an organic EL element, a glass substrate, and the light extraction film of the present invention, and is a glass substrate having an organic EL element formed on one surface thereof. It is an organic EL planar light source provided with the light extraction film of the present invention by adhering the resin adhesive layer in contact with the other surface.

  Examples of the film substrate include a thermoplastic resin and a thermosetting resin. Examples of the thermoplastic resin include acrylic resin, polyester, polycarbonate resin, polyolefin, and cycloolefin polymer, and examples of the thermosetting resin include polyurethane. A substrate mainly composed of a cycloolefin polymer (COP) having excellent optical isotropy and water vapor barrier properties is particularly preferable. In addition, from the viewpoint of excellent heat resistance, polyethylene naphthalate (PEN), polyethersulfone (PES), and the like can also be used.

  Examples of COP include norbornene polymers, copolymers of norbornene and olefins, and polymers of unsaturated alicyclic hydrocarbons such as cyclopentadiene. From the viewpoint of water vapor barrier properties, it is preferable that the main chain and side chain of the constituent molecules do not contain a functional group having a large polarity, such as a carbonyl group or a hydroxyl group.

  The thickness of the substrate 2 is preferably about 0.03 mm to 3.0 mm. If it is this thickness range, the handling is easy, the thinness and lightness of a planar light source can be utilized, and also the intensity | strength with respect to a bending and a scratch can be provided.

  The anode electrode 3 provided on the substrate 2 is not particularly limited. For example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), etc. In addition to these metal oxides, metals such as silver (Ag), chromium (Cr), and the like can be given. From the viewpoint of effectively extracting light generated from the light emitting layer of the organic EL element, ITO or IZO having high transparency can be particularly preferably used.

  The organic EL layer 4 is a layer that is provided between the anode electrode 3 and the cathode electrode 5, has at least one light emitting layer, and is composed of a plurality of layers mainly made of an organic compound. The organic EL layer 4 can be formed of a low molecular dye material or a conjugated polymer material generally used for an organic EL element. The organic EL layer may have a multilayer structure including layers such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer.

  Further, a plurality of dopants exhibiting different light emission may be added to the light emitting layer of the organic EL layer 4. Moreover, you may add a dopant to another layer, for example, an electron carrying layer and a hole carrying layer. If multiple emission colors are seen from different dopants, the desired mixed emission is obtained. When a plurality of emission colors are complementary to each other, white emission is obtained. In the case of adapting to a luminaire, white light is particularly preferable.

  There is no restriction | limiting in particular about the film-forming method of each layer which comprises the organic EL layer 4, It can form by methods, such as a spin coat method other than a vacuum evaporation method, for example. At this time, each layer may be formed by the same film formation method or may be formed by different methods.

  The substance that forms the cathode electrode 5 is not particularly limited, and metals, alloys, electrically conductive compounds, and mixtures thereof can be used.

  In order to protect the organic EL element formed on the substrate 2 in this manner, a light emitter protective layer 9 is formed on the cathode electrode 5 to complete an organic EL panel.

(Light extraction film)
The light extraction film 11 of the present invention comprises a resin adhesive layer 8, a resin lens layer 6, and an inorganic flame retardant layer 7, and a specific inorganic flame retardant layer 7 is interposed between the atmosphere and the resin lens layer. I am letting.

  In such a light extraction film 11 of the present invention, there is an effect that combustion of the resin lens layer can be suppressed without hindering the luminance improvement effect of the resin lens layer 6.

  That is, the inorganic flame retardant layer 7 according to the present invention is formed so as to be in contact with the entire surface of the uneven surface 62 on the light extraction side of the resin lens layer 6, and as shown in FIG. When the direction from the smooth surface 61 of the lens-made lens layer 6 toward the concavo-convex surface 62 is the light extraction direction, the position B of the inorganic flame retardant layer 7 at the apex of the concave portion in the light extraction direction of the concavo-convex surface is the light extraction direction of the concavo-convex surface 62. It is characterized by being closer to the smooth surface 61 than the position A of the convex vertex.

In the present invention, from the viewpoint of imparting sufficient flame retardancy to the planar light source, it is important that the inorganic flame retardant layer 7 is formed on the entire uneven portion of the resin lens layer according to the present invention. . That is, the light extraction film 11 of the present invention has an area of 25 cm ² or more so that it can be applied to a certain area assumed for the planar light source 10 where flame retardancy is important. In addition, the inorganic flame retardant layer 7 is formed over the entire range of the concavo-convex surface 62 of 25 cm ² or more, and the concavo-convex surface 62 of the resin lens layer 6 is formed without being exposed in this range. Is preferred.

(Inorganic flame retardant layer)
The inorganic flame retardant layer 7 according to the present invention is formed on and in contact with the entire surface of the concavo-convex surface 62 of the resin lens layer 6, from the viewpoint of not inhibiting the luminance enhancement effect of the resin lens layer 6. The refractive index is preferably 1.2 to 1.6.

The material of the inorganic flame retardant layer 7 is colorless and transparent at least in the visible light region, and an inorganic material such as silica (SiO _x ), MgF ₂ , Al ₂ O ₃ , TiO ₂ is used as long as the refractive index condition is satisfied. Can be used. These inorganic materials can also be used in combination, and the refractive index may be adjusted by dispersing these materials in SiOx.

As SiO _X , for example, converted silica using polysilazane as a raw material can be preferably used because it has high transparency and a relatively low refractive index. The polysilazane compound has a property of changing to inorganic silica (SiO ₂ ) after drying.

  With respect to the planar light source 10 in which the light extraction film 11 of the present invention is attached to the light extraction surface of the planar light emitter 1 via the resin adhesive layer 8, the inorganic flame retardant layer 7 side of the air exposure surface that is the light extraction surface From the effect of the inorganic flame retardant layer 7, the resin lens layer 6 according to the present invention having an average thickness of at least 10 μm including the lens and the support is present on the light extraction side due to the effect of the inorganic flame retardant layer 7. However, since the flame retardant property of the planar light source is increased, the planar light source according to the present invention can be effectively applied to lighting fixtures and the like that are required to be flame retardant.

  When the inorganic flame retardant layer 7 is formed so as to cover the entire surface of the resin lens layer 6, the average film thickness of the inorganic flame retardant layer 7 needs to be 0.1 μm or more and 5 μm or less. By being in the above range, it is possible to form the inorganic flame retardant layer 7 on the entire surface of the uneven surface 62 without defects, so that it is possible to impart flame retardancy, and also the brightness enhancement effect of the resin lens layer 6, that is, The light extraction effect can be prevented.

  The average film thickness of the inorganic flame retardant layer 7 according to the present invention is preferably 0.2 μm or more and 2.0 μm or less, and more preferably 0.3 μm or more and 1 μm or less. When the film thickness of the inorganic flame retardant layer 7 is large, the transmittance is lowered, and the light extraction efficiency may be lower than when the inorganic flame retardant layer 7 is not provided, and the inorganic flame retardant layer 7 is cracked. This increases the possibility of flame retardancy.

  As a method for forming the inorganic flame retardant layer 7, a spray coating method and a spin coater method are preferable. More preferably, the spin coater method is preferable from the viewpoint that a layer can be easily formed on the entire surface in a preferable shape.

As a preferable shape of the inorganic flame retardant layer 7, the direction from the smooth surface 61 of the resin lens layer 6 to the concavo-convex surface 62 is a light extraction direction, and the layer of the inorganic flame retardant layer 7 at the vertex of the concave portion in the light extraction direction of the concavo-convex surface 62. When the thickness D _{B is} the layer thickness D _A of the inorganic flame retardant layer 7 at the top of the convex portion in the light extraction direction of the concavo-convex surface, a shape satisfying the condition of 0.01 <D _A / D _B <1.0 is preferable. Preferably, 0.05 <D _A / D _B <0.5, and more preferably 0.1 <D _A / D _B <0.3.

(Resin lens layer)
The resin lens layer 6 according to the present invention is a resin layer having a shape composed of a lens and a sheet-like support that supports the lens, and has an uneven surface and a smooth surface as both main surfaces, and is 10 μm or more. It has an average thickness. As shown in Comparative Example 1 described later, when a flame is directly applied to the uneven surface, the surface melts and burns because it is relatively thick.

  By providing the resin lens layer 6 according to the present invention on the light extraction side of the planar light emitter 1 without an air layer, a light emitting element inside the planar light source 10 (for example, the planar light emitter 1). When the organic EL panel is used, the total reflection inside the planar light emitter 1 of the light generated in the organic EL element is changed by changing the light emission angle (referred to as “lens effect” in this specification). As a result, it is known that the effect of improving the luminance, that is, the effect of improving the light extraction efficiency is exhibited.

  The structure of the concavo-convex portion of the resin lens layer 6 according to the present invention is not particularly limited as long as the lens effect is exhibited. For example, a structure having a microlens structure, a pyramid structure, a photonic array structure, or the like. Can be preferably used.

  From the viewpoint of effectively achieving the effects of the present invention while obtaining a large light extraction efficiency, the microlens structure is preferably a resin lens layer, and the average thickness of the layer is preferably 200 μm or less, more preferably They are 30 micrometers or more and 150 micrometers or less, More preferably, they are 50 micrometers or more and 120 micrometers or less, Especially preferably, they are 60 micrometers or more and 100 micrometers or less. From the same viewpoint, the preferable lens diameter is φ10 μm to φ50 μm, more preferably φ20 μm to φ40 μm, and the preferable lens arrangement is closest packing.

  The resin lens layer 6 in the present invention may have a regular structure / arrangement such as the structure of the concavo-convex portion described above, but may also have a random structure / arrangement. By making the structure / arrangement of the concavo-convex portions random, an effect of suppressing light interference can be expected as described in JP-A-2005-276581.

  The preferable uneven height of the uneven portion of the resin lens layer 6 according to the present invention (the height difference between the concave vertex and the convex vertex) is preferably 1 μm to 200 μm, and more preferably 5 μm to 50 μm. More preferably, it is 10 μm to 30 μm. By having the concavo-convex portion in this range, the total reflection of light can be reduced and the light emission angle can be changed, so that the light extraction effect is enhanced.

  The material of the resin lens layer 6 is a resin that exhibits transparency at least in the visible light region and is excellent in moldability. The refractive index of the resin lens layer 6 is preferably 1.4 to 1.8.

  Regarding the lens constituting the shape of the resin lens layer 6 and the sheet-like support that supports the lens, the material of the sheet-like support and the concavo-convex portion, that is, the lens portion may be the same or different. May be used.

Examples of the transparent resin used as the material of the resin lens layer 6 include polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl chloride, melanin resin, and phenol resin. , Alkyd resin, epoxy resin, polyurethane resin, polyester resin, maleic acid resin, polyamide resin, polyimide amide resin, cyclic polyolefin resin, norbornene resin, 4-methylpentene resin, polysulfone resin, polyethersulfone resin, polyarylate resin, Polyethylene terephthalate resin, polyethylene terephthalate resin, polypropylene naphthalate resin, fluorine resin, polyurethane resin, polystyrene resin Polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyester resins, silicone resins, maleic acid resins.
(Resin adhesive layer)
Since the light extraction film 11 of the present invention has the resin adhesive layer 8 on one surface thereof, it can be easily applied to the planar light-emitting body 1.

  The average thickness of the adhesive layer is preferably 5 μm or more and 200 μm or less, more preferably 10 μm or more, from the viewpoint of not reducing the flame retardancy of the planar light source 10 itself while imparting sufficient adhesiveness. It is 100 micrometers or less, More preferably, they are 30 micrometers or more and 70 micrometers or less.

  From the viewpoint of correcting the color temperature depending on the viewing angle of the planar light-emitting body 1, particularly when the light extraction film of the present invention is applied to a white light-emitting planar light-emitting body, the resin adhesive layer 8 is placed inside the layer. It is preferable to use a material containing a diffusing material. As a preferable diffusing material, transparent inorganic fine particles having a particle diameter of 0.2 μm or more and 100 μm or less can be used.

  Next, the preparation procedure of the light extraction film of the specific Example of this invention and a comparative example, and these evaluation results are demonstrated.

Example 1
A resin lens layer film (base film) having a convex hemispherical lens structure with a diameter of 30 μm and a height of 15 μm as an uneven surface on one surface of a B5 size (182 mm × 257 mm) glass substrate (refractive index: 1.52) : Acrylic (refractive index: 1.57, thickness: 81 μm), lens part: acrylic (refractive index: 1.58), resin adhesive with a smooth surface not having the lens structure facing the glass substrate (Refractive index: 1.53) The inside of this pressure-sensitive adhesive contains 1 to 60 wt% of fine particles having a number average particle diameter of 1 μm of an acrylic material as a light diffusing material.

  Next, a sample having a resin lens layer film on one main surface of the glass substrate with a resin adhesive layer interposed therebetween is placed on the other main substrate of the glass substrate that is not provided with a light extraction film on a 1 mm thick aluminum plate. The surface side was stuck through the adhesive layer toward the aluminum plate.

  Next, 0.4 cc of a polysilazane 5 wt% solution is dropped on the center of the sample on the resin lens layer of the aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer structure and rotated at maximum speed. The inorganic flame retardant layer was formed by applying the coating by a spin coating method in which the rotation was maintained at several 500 revolutions / second for 30 seconds, and then converting to silica by drying and heating. The polysilazane used is NAX120-20 manufactured by AZ Electronic Materials.

  The test sample of Example 1 produced in this manner has a structure of aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer / inorganic flame retardant layer. In other words, in this test sample, a light extraction film having a laminated structure of resin adhesive layer / resin lens layer / inorganic flame retardant layer is extracted from a simulated organic EL panel made of an aluminum plate / adhesive layer / glass substrate. It is a sample adhered to the glass substrate surface, which is a surface, and includes an inorganic flame retardant layer in contact with the uneven surface of the resin lens layer, and a resin adhesive layer in contact with the smooth surface of the resin lens layer.

FIG. 2 is an electron micrograph of the resin lens layer portion of the test sample of Example 1 produced as described above. It can be seen that the concave portion of the resin lens layer is thick and the convex portion is thin, and the silica inorganic flame retardant layer is formed on the entire surface including the convex portion. The formed inorganic flame retardant layer 7 has a thickness of about 3 μm at the thicker position and about 0.2 μm at the thinned position. The average thickness per plane area is 0.5 μm, and the value of D _A / D _B is 0.1. Met.

  About the test sample of Example 1 produced as mentioned above, the combustion test was implemented with the combustion test method of the Japan Association of Railway Vehicle Machinery Technology. That is, the center part of the test sample of Example 1 in which the light extraction film was held downwardly by 45 ° was exposed to a flame described later from below to confirm the combustion state of the test sample.

  The flame used in the combustion test was ignited by placing 0.5 cc of pure ethyl alcohol in an alcohol container (iron 17.5 mmφ × 7.1 mm, 0.8 mmt) and left to stand until the fuel was burned out. The alcohol container was placed on a container holder made of cork having a low thermal conductivity so that the distance from the center of the test sample to the center of the bottom of the alcohol container was 25.4 mm (1 inch).

  Combustion judgment is divided into alcohol combustion and after combustion. During combustion, the specimen is observed for ignition, ignition, smoke generation, flame condition, etc. After combustion, afterflame, residual dust, The state of carbonization and deformation was investigated.

  In FIG. 3, the photograph after the combustion test of the center part exposed to the flame of the test sample of Example 1 is shown. In the combustion test of the test sample of Example 1, neither ignition nor after-flame occurred.

(Example 2)
On the light extraction film of the test planar light source of Comparative Example 2 described above, an inorganic flame retardant layer was formed in the same manner as in Example 1, and the test planar light source of Example 2 was obtained. At this time, D _A was 0.3 μm, D _B was 3.0, and D _A / D _B was 0.1.

  In order to evaluate the difference in the presence or absence of the inorganic flame retardant layer, the angle dependence of luminance and the angle dependence of color temperature of the test surface light sources of Comparative Example 2 and Example 2 were compared in FIG. Show.

  By providing the inorganic flame retardant layer, although the color temperature slightly changed, the luminance slightly increased.

(Comparative Example 1)
In the same manner as the test sample preparation procedure of Example 1, the sample up to the structure of aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer was carried out, and an inorganic flame retardant layer was formed on the resin lens layer. A test sample of Comparative Example 1 was produced in the same manner except that it was not formed. This sample has a structure of aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer. In other words, this test sample is a glass substrate which is a simulated light extraction surface of a simulated organic EL panel composed of an aluminum plate / adhesive layer / glass substrate, and a light extraction film having a laminated structure of resin adhesive layer / resin lens layer. In this sample, the uneven surface of the resin lens layer is the outermost surface, and a resin adhesive layer is provided in contact with the smooth surface of the resin lens layer.

  A combustion test was performed on the test sample of Comparative Example 1 in the same manner as in Example 1.

  In FIG. 4, the photograph after the combustion test of the center part exposed to the flame of the test sample of the comparative example 1 is shown. In the combustion test of the test sample of Comparative Example 1, unlike the test sample of Example 1, ignition of the resin lens layer during combustion and after-flame after combustion were observed. Thus, by comparing the results of the combustion test between Example 1 and Comparative Example 1, it is clear that the flame retardancy was increased by using the light extraction film of the present invention.

(Comparative Example 2)
A glass substrate with ITO in which a light-transmitting anode electrode (indium / tin oxide (ITO) is formed on one surface of a glass substrate (refractive index: 1.52) is used, and an organic layer is formed thereon by vacuum evaporation. An EL layer and a light-reflective cathode electrode (Al, film thickness 150 nm) were formed in this order to produce a planar light emitter, which was then sealed with a SiN film in a CVD vapor deposition method to obtain 80.4 mm × 80. An organic EL panel for evaluation of white light emission having a light emitting region of 4 mm was produced.

  Organic EL planar shape in which a light extraction film on which an inorganic flame retardant layer is not formed is attached to the glass surface of the organic EL panel for evaluation by attaching a resin lens layer film in the same manner as in Example 1. A light source was produced as a test surface light source of Comparative Example 2.

(Examples 3 to 5)
Example 2 except that the concentration of the polysilazane solution was 10 wt% (Example 3), 15 wt% (Example 4), and 20 wt% (Example 5) instead of Example 1 and Example 2. Similarly, test surface light sources of Examples 3 to 5 were produced.

  Table 1 shows the measurement and calculation results of the shape of the inorganic flame retardant layer 7 of the test planar light sources of Examples 3 to 5 together with the results of Example 2.

  When the combustion test was performed on the test samples of Examples 3 to 5 in the same manner as in Example 1, the ignition test and the after flame did not occur in the combustion test similar to the test sample of Example 1.

  For the test samples of Examples 3 to 5, the angular dependence and angular dependence of luminance were compared with those of Comparative Example 2. By providing the inorganic flame retardant layer, as in Example 2, the color temperature was slightly changed as compared with Comparative Example 2, but the luminance was almost the same.

  However, in Examples 4 and 5, as the polysilazane concentration is increased, the thickness of the inorganic flame retardant layer becomes too thick, and the luminance is slightly lowered as shown in FIG. 7 and the angle dependence of the color temperature as shown in FIG. Is slightly larger. In other words, the brightness improvement effect itself of the resin lens layer itself was maintained, but it was slightly inferior to that in Example 3.

(Comparative Example 3)
In the same manner as the test sample preparation procedure in Example 1, the sample up to the structure of aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer was carried out. A test sample of Comparative Example 3 was prepared in the same manner except that the sample was leaned against the wall so as to be inclined and the polysilazane solution was spray-coated from the normal direction of the light extraction surface toward the surface.

  Table 2 shows the measurement and calculation results of the shape of the inorganic flame retardant layer 7 of the test sample of Comparative Example 3 coated with a 5 wt% polysilazane solution, together with the results of Comparative Example 4 coated under the same conditions described later.

  FIG. 9 is an electron micrograph of the resin lens layer portion of the test sample of Comparative Example 3 manufactured as described above. Although the silica inorganic flame retardant layer is slightly formed in the concave portion of the resin lens layer, it is not formed in the convex portion.

For the test sample of Comparative Example 3, a combustion test was performed in the same manner as in Example 1.
In the combustion test of the test sample of Comparative Example 3, the resin lens layer was ignited during combustion and after-flame after combustion was observed.

(Comparative Example 4)
In the same manner as the test sample preparation procedure of Example 1, the samples up to the structure of aluminum plate / adhesive layer / glass substrate / resin adhesive layer / resin lens layer were carried out so that the light extraction surface of the sample was directly below. A test sample of Comparative Example 4 was prepared in the same manner except that the sample was attached to the ceiling surface and spray-coated with the polysilazane solution from the direction inclined 45 degrees from the light extraction surface toward the surface.

  FIG. 10 is an electron micrograph of the resin lens layer portion of the test sample of Comparative Example 4 manufactured as described above. Although the silica inorganic flame retardant layer is formed on the convex portion of the resin lens layer, it is not formed on the concave portion.

For the test sample of Comparative Example 4, a combustion test was performed in the same manner as in Example 1.
In the combustion test of the test sample of Comparative Example 4, the resin lens layer was ignited during combustion, and afterflame after combustion was observed.

  In spray coating, formation of the inorganic flame retardant layer in contact with the entire surface of the uneven surface may be successful to some extent in some cases, and in that case, flame retardancy may be imparted, but Comparative Example 3 As shown in -4, although various efforts were made to ensure flame retardancy, it was difficult to stably form an inorganic flame retardant layer on the entire surface and to impart flame retardancy because it was difficult to ensure uniformity. Table 3 shows the results of combustion tests applied using a 5 wt% polysilazane solution. Compared to the results of applying a polysilazane solution by spin coating, there are many cases where the spray coating method combusts. became.

DESCRIPTION OF SYMBOLS 1 Planar light-emitting body 2 Board | substrate 3 Anode electrode 4 Organic EL layer 5 Cathode electrode 6 Resin lens layer 7 Inorganic flame retardant layer 8 Resin adhesive layer 9 Luminescent body protective layer 10 Planar light source 11 Light extraction film 61 Resin lens layer 6 smooth surface 62 Uneven surface of resin lens layer 6

Claims (7)

  A light extraction film having an uneven surface and a smooth surface as both main surfaces and including a resin lens layer having an average thickness of 10 μm or more, and an inorganic film having an average thickness of 5 μm or less in contact with the entire surface of the uneven surface The inorganic flame retardant at the top of the concave portion in the light extraction direction of the concave and convex surface when the direction from the smooth surface to the concave and convex surface is the light extraction direction, comprising a flame retardant layer and a resin adhesive layer in contact with the smooth surface A light extraction film characterized in that the position of the layer is closer to the smooth surface than the position of the convex portion vertex of the light extraction direction of the uneven surface. A said light extraction film having a 25 cm ² or more areas are the inorganic flame retardant layer to the entire range of 25 cm ² or more of the uneven surface of continuous form, and said resin lens layer in the range The light extraction film according to claim 1, wherein the inorganic flame retardant layer is formed without exposing the uneven surface.   The light extraction film according to claim 1, wherein the inorganic flame retardant layer is composed of inorganic silica. When film thickness _{D A} of the inorganic flame retardant layer in the convex apex, the thickness of the inorganic flame retardant layer in the recess apex was _{D B, 0.01 <D A /} D B <1. The light extraction film according to claim 1, which is 0.   The light extraction film according to claim 1, wherein the inorganic flame retardant layer is formed by a spin coater.   The light extraction film according to claim 1, wherein the resin adhesive layer contains a diffusing material inside the layer.   An organic EL planar light source comprising an organic EL element, a glass substrate, and the light extraction film according to any one of claims 1 to 6, wherein the organic EL element is formed on one surface of the glass substrate. An organic EL planar light source comprising the light extraction film by adhering the resin adhesive layer in contact with the other surface.