JP6790345B2 - Wavelength conversion sheet - Google Patents

Description

The present invention relates to a light emitting body protective film, a wavelength conversion sheet and an electroluminescence light emitting unit.

In a light emitting unit such as a backlight unit and an electroluminescence light emitting unit of a liquid crystal display, the performance of the light emitting body may deteriorate as a long time elapses when the light emitting body comes into contact with oxygen or water vapor. For this reason, in these light emitting units, a gas barrier film in which a gas barrier layer is formed on a polymer film is often used as a protective film for a light emitting body (see, for example, Patent Document 1).

International Publication No. 2015/013225

However, in the production of the protective film, when the gas barrier layer is formed, damage due to foreign matter contamination and minute defects such as cracks may occur in the gas barrier layer. Further, for example, when the gas barrier layer is formed by the thin-film deposition method and the vapor-filmed material is scattered (splash), the gas barrier layer causes larger defects, and in some cases, defects penetrating the polymer film and the gas barrier layer occur. It is possible. These defects serve as an entry route for oxygen, water vapor, and the like. As a result, when a protective film having the above-mentioned defects in the gas barrier layer is used for the light emitting unit, dark spots may be generated in a portion close to the above-mentioned defects.

The present invention has been made in view of the above problems, and when used in a light emitting unit, a light emitting body protective film capable of suppressing the generation of dark spots even if the barrier layer has a defect, and It is an object of the present invention to provide a wavelength conversion sheet and an electroluminescence light emitting unit obtained by using this.

The present invention is a light emitting body protective film in which a first optical film and a second optical film are bonded together via an adhesive layer, and the first optical film is on the first base material layer and the first base material layer. An optical barrier film including a first barrier layer formed on the surface of the film, wherein the second optical film includes a second base material layer and a second barrier layer formed on the second base material layer. Provided is a light emitting body protective film in which the oxygen permeability of the adhesive layer is 1000 cm ³ / (m ² · day · atm) or less at a thickness of 5 μm.

According to the present invention, by forming the protective film as a laminate of an optical barrier film in which a first optical film and a second optical film are laminated, damage to the light emitting body layer due to an external force is suppressed when used in a light emitting unit. Moreover, the gas barrier property can be improved. Further, it is assumed that the luminescent material protective film has a defect in the first barrier layer or the second barrier layer because the oxygen permeability of the adhesive layer is 1000 cm ³ / (m ² · day · atm) or less. However, the occurrence of dark spots can be suppressed.

In the luminescent material protective film, it is preferable that the adhesive layer is formed from an adhesive containing an epoxy resin. When the adhesive layer has the above structure, the adhesion between the first optical film and the second optical film can be improved.

In the light emitting body protective film, it is preferable that the first optical film and the second optical film are bonded to each other via the adhesive layer so that the first barrier layer and the second barrier layer face each other. .. By arranging the first optical film and the second optical film as described above, the first barrier layer and the second barrier layer can be protected from an external force, and more stable gas barrier properties can be obtained.

In the luminescent material protective film, the first barrier layer includes a first inorganic thin film layer and a first gas barrier coating layer, and the second barrier layer includes a second inorganic thin film layer and a second gas barrier coating layer. Is preferable. When the first barrier layer and the second barrier layer have the above structure, more excellent gas barrier properties can be obtained.

The present invention also provides a wavelength conversion sheet including the light emitting body protective film and a phosphor layer formed on the first optical film of the light emitting body protective film. The present invention further provides an electroluminescence light emitting unit including the light emitting body protective film and an electroluminescence light emitting body layer formed on the first optical film of the light emitting body protective film.

According to the present invention, when used in a light emitting unit, a light emitting body protective film capable of suppressing the generation of dark spots even if the barrier layer has a defect, and a wavelength conversion obtained by using the film. A sheet and an electroluminescence light emitting unit can be provided.

It is the schematic sectional drawing of the light emitting body protection film which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the wavelength conversion sheet which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the mechanism of dark spot generation assumed in the wavelength conversion sheet which has a defect in the barrier layer arranged on the phosphor layer side. It is the schematic sectional drawing of the backlight unit obtained by using the wavelength conversion sheet which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the electroluminescence light emitting unit which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments.

(Luminescent protective film)
FIG. 1 is a schematic cross-sectional view of a light emitting body protective film according to the present embodiment. In the light emitting body protective film 10 of FIG. 1, the first optical film 16a and the second optical film 16b are bonded to each other via an adhesive layer 15. The first optical film 16a is an optical barrier film including a first base material layer 11a and a first barrier layer 14a formed on the first base material layer 11a. The first optical film 16a may include two or more first barrier layers 14a. When the first optical film 16a includes two or more first barrier layers 14a, the configurations of the plurality of first barrier layers 14a may be the same or different. The second optical film 16b is an optical barrier film including a second base material layer 11b and a second barrier layer 14b formed on the second base material layer 11b. The first optical film 16a and the second optical film 16b are bonded to each other via the adhesive layer 15 so that the first barrier layer 14a and the second barrier layer 14b face each other. Further, the second optical film 16b may include two or more second barrier layers 14b. When the second optical film 16b includes two or more second barrier layers 14b, the configurations of the plurality of second barrier layers 14b may be the same or different. The configurations of the first barrier layer 14a and the second barrier layer 14b may be the same or different. When the light emitting body protective film 10 is used for the light emitting unit, the light emitting body protective film 10 is arranged so that the first optical film 16a is in contact with the light emitting body layer. Since the light emitting body protective film 10 is a laminated body of an optical barrier film in which the first optical film 16a and the second optical film 16b are laminated, damage to the light emitting body layer due to an external force is suppressed when used in a light emitting unit. Moreover, the gas barrier property can be improved.

The oxygen permeability of the adhesive layer 15 is 1000 cm ³ / (m ² · day · atm) or less in the thickness direction at a thickness of 5 μm. Preferably the oxygen permeability ^{500cm 3 / (m 2 · day} · atm) or ^less, 100 cm ³ / more preferably (m 2 · day · atm) or ^{less, 50cm 3 / (m 2 ·} day -Atm) or less is more preferable, and 10 cm ³ / (m ² · day · atm) or less is particularly preferable. Since the oxygen permeability of the adhesive layer 15 is 1000 cm ³ / (m ² · day · atm) or less, dark spots are suppressed even if the barrier layer has defects when used in a light emitting unit. It is possible to obtain a light emitting body protective film 10 which can be used. The lower limit of the oxygen permeability is not particularly limited, but is, for example, 0.1 cm ³ / (m ² · day · atm).

A protective film having a structure in which an optical film having a barrier layer and another optical film having a barrier layer are bonded to each other via an adhesive layer (barrier film laminated structure) like the light emitting body protective film 10 according to the present embodiment. Therefore, an excellent gas barrier property can be obtained as compared with a protective film composed of only an optical film having a barrier layer (not having a barrier film laminated structure). However, although the gas barrier property of the protective film as a whole can be obtained by the above-mentioned laminated structure of the barrier film, the barrier layer is formed when local minute defects occur in the barrier layer (particularly the barrier layer arranged near the illuminant layer). It may not be possible to sufficiently suppress the occurrence of dark spots in the illuminant layer near the minute defects generated in the film. Such local minute defects are unlikely to appear in the gas barrier property of the protective film as a whole, which is evaluated by measuring the gas transmittance or the like, but they affect the generation of dark spots in the vicinity of the defects. In the light emitting body protective film 10 according to the present embodiment, even if a local minute defect is generated in the barrier layer by bonding the first optical film 16a and the second optical film 16b via the adhesive layer 15. , It is possible to suppress the occurrence of dark spots in the vicinity of the defect. Further, the effect obtained by the light emitting body protective film 10 according to the present embodiment is not limited to the case where the above-mentioned minute defects occur, and even if a large defect occurs in the barrier layer during the production of the protective film, the vicinity of the defect is present. It is possible to suppress the occurrence of dark spots. Further, according to the light emitting body protective film 10 according to the present embodiment, even if a defect penetrating the barrier layer and the base material layer occurs during the production of the protective film, dark spots in the vicinity of the defect may occur. It can be suppressed.

The adhesive layer 15 is formed of an adhesive or an adhesive. Examples of the adhesive include acrylic adhesives, epoxy adhesives, urethane adhesives and the like. The adhesive preferably contains an epoxy resin. When the adhesive contains an epoxy resin, the adhesion between the first optical film 16a and the second optical film 16b can be improved. Examples of the pressure-sensitive adhesive include acrylic pressure-sensitive adhesives, polyvinyl ether-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, starch-based adhesives, and the like. The thickness of the adhesive layer 15 is preferably 0.5 to 50 μm, more preferably 1 to 20 μm, and even more preferably 2 to 6 μm. When the thickness of the adhesive layer 15 is 0.5 μm or more, the adhesion between the first optical film 16a and the second optical film 16b can be easily obtained, and when the thickness is 50 μm or less, it is more excellent. It becomes easier to obtain a good gas barrier property.

The first base material layer 11a and the second base material layer 11b are layers for suppressing damage in processing, distribution, and the like. Examples of the first base material layer 11a and the second base material layer 11b include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon; polyolefins such as polypropylene and cycloolefins; polycarbonates; and triacetyls. Examples include, but are not limited to, cellulose and the like. The first base material layer 11a and the second base material layer 11b are preferably a polyester film, a polyamide film or a polyolefin film, more preferably a polyester film or a polyamide film, and further preferably a polyethylene terephthalate film. .. Further, it is preferable that the first base material layer 11a and the second base material layer 11b are biaxially stretched. The first base material layer 11a and the second base material layer 11b may be the same or different.

The thickness of the first base material layer 11a and the second base material layer 11b is not particularly limited, but is preferably 3 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less.

A first barrier layer 14a and a second barrier layer 14b are formed on the first base material layer 11a and the second base material layer 11b, respectively, via an anchor coat layer (not shown), if necessary. Examples of the anchor coat layer include polyester resin, and the thickness of the anchor coat layer is about 0.01 to 1 μm.

The first barrier layer 14a preferably includes a first inorganic thin film layer 12a and a first gas barrier coating layer 13a, and the second barrier layer 14b includes a second inorganic thin film layer 12b and a second gas barrier coating layer 13b. It is preferable to include it. In this case, the second optical film 16b is bonded via the adhesive layer 15 so that the first barrier layer 14a and the second barrier layer 14b face each other. When the first barrier layer 14a and the second barrier layer 14b have the above configuration, more excellent gas barrier properties can be obtained. Further, by arranging the second optical film 16b as described above, the first barrier layer 14a and the second barrier layer 14b can be protected from an external force, and more stable gas barrier properties can be obtained.

The first inorganic thin film layer 12a and the second inorganic thin film layer 12b contain an inorganic compound, and preferably contain a metal oxide. Examples of the metal oxide include oxides of metals such as aluminum, copper, silver, yttrium, tantalum, silicon, and magnesium. The metal oxide is preferably silicon oxide (SiOx, x is 1.0 to 2.0) because it is inexpensive and has excellent barrier performance. When x is 1.0 or more, good gas barrier properties tend to be easily obtained.

The method for forming the first inorganic thin film layer 12a and the second inorganic thin film layer 12b is preferably vacuum film formation. Examples of the vacuum film formation include a physical vapor deposition method and a chemical vapor deposition method. Examples of the physical vapor deposition method include a vapor deposition method, a sputtering method, an ion plating method, and the like. Moreover, as a chemical vapor deposition method, for example, a thermal CVD method, a plasma CVD method, an optical CVD method and the like can be mentioned. From the viewpoint of manufacturing cost, the first inorganic thin film layer 12a or the second inorganic thin film layer 12b is preferably an inorganic vapor deposition film layer formed by a vapor deposition method. For example, when the first inorganic thin film layer 12a or the second inorganic thin film layer 12b is an inorganic vapor deposition film layer, holes may be formed in the first optical film 16a or the second optical film 16b due to splashing of the vapor deposition material. .. Although splashes occur infrequently, the holes created by the splashes are relatively large defects and can be holes that penetrate the barrier layer and the substrate layer. Therefore, in the protective film in which the holes are formed by the splash, the gas barrier property can be significantly reduced. In particular, when holes penetrating the first barrier layer 14a and the first base material layer 11a arranged on the light emitting body layer side are formed, dark spots are more likely to occur. However, since the light emitting body protective film 10 according to the present embodiment has a barrier film laminated structure, even if the first optical film 16a or the second optical film 16b has a relatively large defect, the gas barrier property is deteriorated. Can be reduced. Since the light emitting body protective film 10 according to the present embodiment further includes an adhesive layer 15, even if the first optical film 16a has such a relatively large defect, it is the same as when there is no defect. The occurrence of dark spots can be suppressed. Therefore, since the first inorganic thin film layer 12a is an inorganic vapor-deposited film layer, it is possible to suppress the generation of dark spots while reducing the manufacturing cost.

The thickness of the first inorganic thin film layer 12a and the second inorganic thin film layer 12b is preferably 10 to 300 nm, and more preferably 20 to 100 nm. When the thickness of the first inorganic thin film layer 12a and the second inorganic thin film layer 12b is 10 nm or more, a uniform film tends to be easily obtained, and gas barrier properties tend to be easily obtained. On the other hand, when the thickness of the first inorganic thin film layer 12a and the second inorganic thin film layer 12b is 300 nm or less, the first inorganic thin film layer 12a and the second inorganic thin film layer 12b can maintain flexibility. There is a tendency that cracks and the like are less likely to occur due to external forces such as bending and tension after the film.

The first gas barrier coating layer 13a and the second gas barrier coating layer 13b are formed from a composition containing at least one selected from the group consisting of a metal alkoxide represented by the following formula (1) and a hydrolyzate thereof. Is preferable.
M (OR ¹ ) _m (R ² ) _nm ... (1)

In the above formula (1), R ¹ and R ² are independently monovalent organic groups having 1 to 8 carbon atoms, and are preferably alkyl groups such as a methyl group and an ethyl group. M represents an n-valent metal atom such as Si, Ti, Al, Zr. m is an integer of 1 to n. Examples of the metal alkoxide include tetraethoxysilane [Si (OC ₂ H ₅ ) ₄ ] and triisopropoxyaluminum [Al (O-iso-C ₃ H ₇ ) ₃ ]. The metal alkoxide is preferably tetraethoxysilane or triisopropoxyaluminum because it is relatively stable in an aqueous solvent after hydrolysis. Examples of the metal alkoxide hydrolyzate include silicic acid (Si (OH) ₄ ), which is a hydrolyzate of tetraethoxysilane, and aluminum hydroxide (Al (OH) ₃ ), which is a hydrolyzate of tripropoxyaluminum. ) Etc. can be mentioned. These are not limited to one type, and a plurality of types can be used in combination. The content of the metal alkoxide and its hydrolyzate in the above composition is, for example, 10 to 90% by mass.

The composition may further contain a hydroxyl group-containing polymer compound. Examples of the hydroxyl group-containing polymer compound include water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone and starch. The hydroxyl group-containing polymer compound is preferably polyvinyl alcohol from the viewpoint of barrier properties. These are not limited to one type, and a plurality of types can be used in combination. The content of the hydroxyl group-containing polymer compound in the above composition is, for example, 10 to 90% by mass.

The thickness of the first gas barrier coating layer 13a and the second gas barrier coating layer 13b is preferably 50 to 1000 nm, and preferably 100 to 500 nm. When the thickness of the first gas barrier coating layer 13a and the second gas barrier coating layer 13b is 50 nm or more, more sufficient gas barrier properties tend to be obtained, and when it is 1000 nm or less, sufficient flexibility is provided. Tends to be retained.

The light emitting body protective film 10 may further include a matte layer (not shown) on the surface of the second optical film 16b side in order to exert a light scattering function. By providing the light emitting body protective film 10 with a matte layer, it is possible to obtain an interference fringe (moire) prevention function, an antireflection function, and the like in addition to the light scattering function.

The illuminant protective film 10 can be suitably used as a protective film for a illuminant that can deteriorate due to contact with oxygen, water vapor, or the like. Examples of the illuminant include a phosphor such as a quantum dot and an electroluminescence illuminant.

(Wavelength conversion sheet)
FIG. 2 is a schematic cross-sectional view of a wavelength conversion sheet according to an embodiment of the present invention. The wavelength conversion sheet is a sheet capable of converting a part of the wavelengths of light from the light source of the backlight unit for a liquid crystal display. As shown in FIG. 2, the wavelength conversion sheet 20 of the present embodiment includes a first protective film, a phosphor layer 21 formed on the first protective film, and a first protective film provided on the phosphor layer 21. (Ii) Protective film 22 is provided. The wavelength conversion sheet 20 has a structure in which the phosphor layer 21 is wrapped (that is, sealed) between the first protective film and the second protective film 22. In FIG. 2, the above-mentioned illuminant protective film 10 is used as the first protective film. On the other hand, as the second protective film 22, the above-mentioned illuminant protective film 10 may be used, or another protective film may be used. Further, the wavelength conversion sheet 20 does not necessarily have to include the second protective film 22. That is, the wavelength conversion sheet 20 of the present embodiment includes a light emitting body protective film 10 and a phosphor layer 21 formed on the first optical film 16a of the light emitting body protective film 10.

As described above, the gas barrier property is improved by providing the protective film with a structure in which a plurality of films having a barrier layer are bonded to each other via an adhesive layer (barrier film laminated structure). It is considered that the mechanism of dark spot generation in the phosphor layer is dominated by the intrusion of gas in the thickness direction of the protective film from the surface of the protective film opposite to the phosphor layer (outside). It is considered that the invasion of gas from the above direction can be reduced by providing the protective film 10 with a barrier film laminated structure. However, when the protective film has a defect in the barrier layer (particularly, the barrier layer arranged on the phosphor layer side), even if the invasion of gas from the outer surface can be reduced, the phosphor layer in the vicinity of the defect can be reduced. It may not be possible to suppress the occurrence of dark spots. The mechanism by which such dark spots occur is not always clear, but the present inventors consider it as follows. FIG. 3 is a conceptual diagram showing a mechanism of dark spot generation assumed in a wavelength conversion sheet having a defect in the barrier layer arranged on the phosphor layer side. In the wavelength conversion sheet 200 of FIG. 3, oxygen, water vapor, and the like in the atmosphere enter from the end surface of the adhesive layer 150 of the light emitting body protective film 100 and diffuse in the surface direction of the adhesive layer 150. When the illuminant protective film 100 has a defect 23 in the first barrier layer 140a, diffused oxygen, water vapor, or the like reaches the phosphor layer 210 through the defect 23. Deterioration of the phosphor progresses around the location of the defect 23, and appears as a dark spot 24 with the passage of time. When the defect 23 penetrates the first base material layer 110a together with the first barrier layer 140a, it is considered that the deterioration of the phosphor becomes remarkable and the dark spot 24 becomes easily visible. That is, oxygen, water vapor, etc. pass from the end face of the adhesive layer 150 through the defect 23 of the first optical film 160a having a gas barrier property, and the phosphor is deteriorated. When oxygen or water vapor in the atmosphere invades the second optical film 160b including the second base material layer 110b and the second barrier layer 140b from the opposite side of the phosphor layer 210 in the thickness direction of the illuminant protective film 100. It was thought that the distance when invading from the end face of the adhesive layer 150 would be extremely large and the amount of invasion would be extremely small compared to the distance shown in FIG. It can be said that there was. According to the wavelength conversion sheet 20 of the present embodiment, by using the light emitting body protective film 10 as the protective film provided on the phosphor layer 21, the light emitting body protective film 10 has a defect in the barrier layer. Even if it does, the occurrence of dark spots can be suppressed.

The phosphor layer 21 contains a resin and a phosphor. The thickness of the phosphor layer 21 is several tens to several hundreds μm. As the resin, for example, a photocurable resin or a thermosetting resin can be used. The phosphor layer 21 preferably contains two types of phosphors composed of quantum dots. Further, the phosphor layer 21 may be a stack of two or more layers of a phosphor layer containing one type of phosphor and a phosphor layer containing another type of phosphor. As the two types of phosphors, those having the same excitation wavelength are selected. The excitation wavelength is selected based on the wavelength of the light emitted by the light source of the backlight unit. The fluorescent colors of the two types of phosphors are different from each other. When a blue light emitting diode (blue LED) is used as a light source, each fluorescent color is red and green. The wavelength of each fluorescence and the wavelength of the light emitted by the light source are selected based on the spectral characteristics of the color filter. The peak wavelength of fluorescence is, for example, 610 nm for red and 550 nm for green.

Next, the particle structure of the phosphor will be described. As the phosphor, core-shell type quantum dots having particularly good luminous efficiency are preferably used. The core-shell type quantum dot is a semiconductor crystal core as a light emitting portion coated with a shell as a protective film. For example, cadmium selenide (CdSe) can be used for the core, and zinc sulfide (ZnS) can be used for the shell. The quantum yield is improved by covering the surface defects of the CdSe particles with ZnS having a large bandgap. Further, the phosphor may have a core double-coated with a first shell and a second shell. In this case, CdSe can be used for the core, zinc selenide (ZnSe) can be used for the first shell, and ZnS can be used for the second shell.

The phosphor layer 21 may have a single-layer structure in which all the fluorescent substances are dispersed in a single layer, and has a multi-layer structure in which each fluorescent substance is separately dispersed in a plurality of layers and these are laminated. You may be doing it.

Next, the method of manufacturing the wavelength conversion sheet 20 of the present embodiment will be described with reference to FIG. The method for forming the phosphor layer 21 is not particularly limited, and examples thereof include the methods described in Japanese Patent Application Laid-Open No. 2013-544018. A phosphor is dispersed in a binder resin, and the prepared phosphor dispersion is applied onto the surface of the first protective film (illuminant protective film 10) on the first optical film 16a side, and then the second protective film 22 is applied to the coated surface. The wavelength conversion sheet 20 can be manufactured by laminating the two films and curing the phosphor layer 21. On the contrary, the phosphor dispersion liquid is coated on one surface of the second protective film 22, and the light emitter protective film 10 is bonded to the coated surface so that the first optical film 16a faces the phosphor layer 21. The wavelength conversion sheet 20 can also be manufactured by curing the phosphor layer 21.

[Backlight unit]
A backlight unit can be obtained by using the wavelength conversion sheet 20. FIG. 4 is a schematic cross-sectional view of a backlight unit obtained by using the wavelength conversion sheet 20. In FIG. 4, the backlight unit 30 includes a light source 32 and the wavelength conversion sheet 20, and the illuminant protective film 10 is arranged on the side opposite to the light source 32 with the phosphor layer 21 interposed therebetween. Specifically, in the backlight unit 30, the light guide plate 34 and the reflector 36 are arranged in this order on the surface of the wavelength conversion sheet 20 on the second protective film 22 side, and the light source 32 is on the side of the light guide plate 34 ( It is arranged in the plane direction of the light guide plate 34).

The light guide plate 34 and the reflector 36 efficiently reflect and guide the light emitted from the light source 32, and known materials are used. As the light guide plate 34, for example, acrylic, polycarbonate, cycloolefin film and the like are used. The light source 32 is provided with, for example, a plurality of blue light emitting diode elements. The light emitting diode element may be a purple light emitting diode or a light emitting diode having a lower wavelength. Light emitted from the light source 32 is incident on the light guide plate 34 (D ₁ direction) is incident on the phosphor layer 21 with the reflection and refraction, etc. (D ₂ direction). The light that has passed through the phosphor layer 21 becomes white light by mixing the light before passing through the phosphor layer 21 with the yellow light generated in the phosphor layer 21.

[Electroluminescence light emitting unit]
FIG. 5 is a schematic cross-sectional view of an electroluminescence light emitting unit according to an embodiment of the present invention. The electroluminescence light emitting unit 50 according to the present embodiment includes an electroluminescence light emitting body layer 56 and a light emitting body protective film 10. The electroluminescence light emitting unit 50 includes, for example, a transparent electrode layer 54, an electroluminescence light emitting body layer 56 provided on the transparent electrode layer 54, and a dielectric layer 58 provided on the electroluminescence light emitting body layer 56. , The electrode element including the back electrode layer 60 provided on the dielectric layer 58 is sandwiched between the first protective film and the second protective film 62 and sealed. In the electroluminescence light emitting unit, the above-mentioned illuminant protective film 10 is used as the first protective film. The electroluminescence light emitting body layer 56 is formed on the first optical film 16a of the light emitting body protective film 10.

In the electroluminescence light emitting unit, dark spot generation can be considered by a mechanism similar to the mechanism described for the wavelength conversion sheet. According to the electroluminescence light emitting unit 50 according to the present embodiment, the light emitting body protective film 10 is used as the protective film provided on the electrode element including the electroluminescence light emitting body layer 56. Even if the barrier layer has a defect, the generation of dark spots can be suppressed.

Each electrode layer, electroluminescence illuminant layer, and dielectric layer can be formed by, for example, a vapor deposition method, a sputtering method, or the like, using a known material.

Hereinafter, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited thereto.

[Preparation of illuminant protective film]
( Reference example 1)
Acrylic polyol and tolylene diisocyanate are mixed so that the number of NCO groups of tolylene diisocyanate is equal to the number of OH groups of acrylic polyol, and ethyl acetate is used so that the total solid content is 5% by mass. Diluted. Β- (3,4 epoxycyclohexyl) trimethoxysilane was further added to the diluted mixed solution so as to be 5% by mass with respect to the total solid content, and these were mixed to obtain an anchor coat layer composition. Made.

The anchor coat layer composition is applied on one surface of a biaxially stretched polyethylene terephthalate film (first base material layer, thickness: 25 μm) by a bar coating method, and dried and cured at 100 ° C. for 1 minute to increase the thickness. An anchor coat layer having a size of 50 nm was formed.

Using a vacuum vapor deposition apparatus of the electron beam heating type, a silicon oxide material (SiO, Canon Optron Ltd.) and evaporated by electron beam heating under a pressure of 1.5 × 10 -2 ^Pa, the above anchor coat layer A SiO _x film (first inorganic thin film layer) having a thickness of 30 nm was formed. The accelerating voltage in the vapor deposition was 40 kV, and the emission current was 0.2 A.

Next, 10.4 parts by mass of tetraethoxysilane and 89.6 parts by mass of hydrochloric acid (concentration: 0.1N) were mixed, and the mixed solution was stirred for 30 minutes to obtain a hydrolyzed solution of tetraethoxysilane. On the other hand, polyvinyl alcohol was dissolved in a mixed solvent of water / isopropyl alcohol (water / isopropyl alcohol (mass ratio) = 90:10) to obtain a 3% by mass polyvinyl alcohol solution. 60 parts by mass of the hydrolyzed solution of tetraethoxysilane and 40 parts by mass of the polyvinyl alcohol solution were mixed to obtain a gas barrier coating layer composition.

The gas barrier coating layer composition was applied onto the first inorganic thin film layer and dried to form a first gas barrier coating layer having a thickness of 300 nm. Further, another first inorganic thin film layer having a thickness of 30 nm is formed on the first gas barrier coating layer in the same manner as described above, and another first inorganic thin film layer having a thickness of 300 nm is formed on the other first inorganic thin film layer. A first gas barrier coating layer was formed. As described above, the first base material layer, the anchor coat layer, the first inorganic thin film layer, the first gas barrier coating layer, the first inorganic thin film layer, and the first gas barrier coating layer are laminated in this order. An optical film was obtained.

The anchor coat layer composition is applied on one surface of a biaxially stretched polyethylene terephthalate film (second base material layer, thickness: 25 μm) by a bar coating method, and dried and cured at 100 ° C. for 1 minute to increase the thickness. An anchor coat layer having a size of 50 nm was formed.

Using a vacuum vapor deposition apparatus of the electron beam heating type, a silicon oxide material (SiO, Canon Optron Ltd.) and evaporated by electron beam heating under a pressure of 1.5 × 10 -2 ^Pa, the above anchor coat layer A SiO _x film (second inorganic thin film layer) having a thickness of 30 nm was formed. The accelerating voltage in the vapor deposition was 40 kV, and the emission current was 0.2 A.

The gas barrier coating layer composition was applied onto the second inorganic thin film layer and dried to form a second gas barrier coating layer having a thickness of 300 nm. As described above, a second optical film obtained by laminating a second base material layer, an anchor coat layer, a second inorganic thin film layer, and a second gas barrier coating layer in this order was obtained.

The following adhesive A is applied on the surface of the first gas barrier coating layer of the obtained first optical film, and the second gas barrier coating layer of the second optical film is bonded to the coated surface of the adhesive A. , 50 ° C. for 2 days. As described above, the first optical film and the second optical film were bonded together via an adhesive layer having a thickness of 5 μm. The adhesive A is an adhesive composition obtained by mixing a main agent made of an epoxy resin and a curing agent made of a polyamine resin.

Next, on the surface of the second optical film on the side where the first optical film is not bonded, 100 parts by mass of acrylic resin (trade name: Akaridic, manufactured by DIC) and silica particles (trade name: Tospearl 120, average). A composition consisting of 20 parts by mass of a particle size: 2.0 μm, manufactured by Momentive Performance Materials Co., Ltd. was applied. The coating film was heated to cure the acrylic resin to form a matte layer having a thickness of 3 μm. As described above, a light emitting body protective film obtained by laminating the first optical film, the adhesive layer, the second optical film, and the matte layer in this order was obtained.

(Example 2 , Reference Example 3 and Comparative Examples 1 to 3)
The same as in Reference Example 1 except that the adhesive shown in Table 1 below was used instead of the adhesive A as the adhesive used when the first optical film and the second optical film were bonded together. , Example 2 , Reference Example 3 and Comparative Examples 1 to 3 were obtained. In Reference Example 3, instead of aging, an electron beam was irradiated at a dose of 15 Mrad to cure the adhesive C.

[Evaluation of illuminant protective film]
(Oxygen permeability of adhesive layer)
The adhesives A to F used in Examples and Comparative Examples are applied onto a CPP (non-stretched polypropylene film) having a thickness of 70 μm, and the CPP having a thickness of 70 μm is attached to the coated surface of the adhesive for aging or aging. Electron beam irradiation was performed. Adhesives A to B and adhesives D to F were aged at 50 ° C. for 5 days. The adhesive C was irradiated with an electron beam at a dose of 15 Mrad. As described above, a sample (laminated body) for measuring oxygen permeability was obtained in which a CPP having a thickness of 70 μm, an adhesive layer having a thickness of 5 μm, and a CPP having a thickness of 70 μm were laminated in this order. The obtained sample was placed in a differential pressure type gas permeability measuring device (GTR-30X manufactured by GTR Tech Co., Ltd.), and the temperature was 40 ° C. and the relative humidity was 0 according to the method described in JIS K7126-1 (Annex 1). The oxygen permeability of the above sample was measured by a differential pressure method at a differential pressure of 101 kPa (1 atm) using oxygen as the test gas in an environment of%. The measurement results of oxygen permeability are shown in Table 1. Incidentally, as a film that is bonded by an adhesive, a high oxygen permeability than the adhesive layer ^{(e.g., 1000cm 3 / (m 2 ·} day · atm) higher oxygen permeability) by using a film having said sample The measurement result of can be regarded as the oxygen permeability of the adhesive layer. In the above measurement method, as a film that is bonded by an adhesive, since it is used CPP oxygen permeability ^{2500cm 3 / (m 2 · day} · atm), 2500cm 3 / (m 2 · day · atm ) The measurement result of the oxygen permeability of the following samples can be regarded as the oxygen permeability of the adhesive layer.

(Adhesion)
The illuminant protective film obtained in Examples and Comparative Examples was cut into strips having a width of 15 mm, and the first optical film side of the illuminant protective film was fixed on a glass plate. Using a Tencilon tensile tester (manufactured by Orientec), the second optical film of the fixed strip-shaped illuminant protective film was first applied in the direction perpendicular to the glass plate at a speed of 300 mm / min. It was peeled off from the optical film, and the strength required for the peeling was measured. The above strength was adjusted to the temperature 23 ° C. humidity 65% RH with respect to the light emitting body protective film (condition (1)) immediately after production, temperature 60 ° C. and humidity 90% RH 1000 hours after storage. It was measured in the environment of. Table 1 shows the measurement results of the peel strength measured under the conditions (1) and (2) as the evaluation results of the adhesion. It was judged that suitable adhesion was obtained when the peel strength was 1N or more, and particularly suitable adhesion was obtained when the peel strength was 3N or more.

The details of the adhesives described in Table 1 are as follows.
Adhesive A: Maxive manufactured by Mitsubishi Gas Chemical Company, Inc., compounding ratio (epoxy resin-based main agent / amine-based curing agent / methanol / ethyl acetate = 1/3/3/6 (mass ratio))
Adhesive B: Polyacrylic acid-based adhesive, compounding ratio (polyacrylic acid aqueous solution in which 5 mol% of carboxyl groups are neutralized with sodium hydroxide aqueous solution / glycerin = 1/1 (solid content mass ratio)).
Adhesive C: A mixture of an amine compound solution and an unsaturated carboxylic acid solution (amine compound solution / unsaturated carboxylic acid solution = 1: 1 (mass ratio)). The amine compound solution is a water / isopropyl alcohol mixed solution (3% by mass, water / isopropyl alcohol = 50/50 (mass ratio)) of the amine compound (manufactured by Nippon Catalyst Co., Ltd., trade name: Epomin SP110) and is unsaturated. The carboxylic acid solution is a water / isopropyl alcohol mixed solution (3% by mass, water / isopropyl alcohol = 50:50 (mass ratio)) of unsaturated carboxylic acid (Itaconic acid manufactured by Kanto Chemical Co., Ltd.).
Adhesive D: manufactured by Toyo Morton Co., Ltd., compounding ratio (epoxy resin-based main agent AD-393 / amine-based curing agent CTA-5 / isopropyl alcohol = 5 / 0.3 / 2.7 (mass ratio)).
Adhesive E: Mitsui Chemicals, Inc., compounding ratio (ester-based main agent Takelac A-525 / isocyanate-based curing agent Takenate A-52 / ethyl acetate = 90/10/100 (mass ratio)).
Adhesive F: manufactured by Saiden Chemical Co., Ltd., compounding ratio (polyxol resin-based main agent X-313-405S / polyisocyanate-based curing agent K-341 / toluene = 25 / 0.34 / 31.25 (mass ratio)).

In Reference Example 1 in which a composition containing an epoxy resin was used as an adhesive, a sufficient peel strength exceeding 5N was obtained. Further, in Comparative Example 2 using the adhesive E, foaming occurred in the adhesive layer during the curing reaction, and the illuminant protective film became cloudy.

[Preparation of wavelength conversion sheet]
A phosphor (trade name: CdSe / ZnS 530, manufactured by SIGMA-ALDRICH) having a core-shell structure in which cadmium selenide (CdSe) particles are coated with zinc sulfide (ZnS) is dispersed in a solvent to adjust the concentration. A phosphor dispersion was prepared in. The above fluorescent material dispersion was mixed with an epoxy-based photosensitive resin to obtain a fluorescent material composition. The phosphor composition was applied onto the surface of the light emitter protective film obtained in Examples and Comparative Examples on the side of the first optical film to form a phosphor layer having a thickness of 100 μm.

The second light emitter protective film obtained in the same Example and Comparative Example was further arranged and laminated on the phosphor layer so that the first optical film faces the phosphor layer side, and then irradiated with ultraviolet rays. By curing the phosphor layer (photosensitive resin) with the above method, a wavelength conversion sheet using the illuminant protective film produced in Examples and Comparative Examples was obtained.

[Evaluation of wavelength conversion sheet]
(Needle hole evaluation)
In the production of the wavelength conversion sheet, as the first optical film of one of the light emitting body protective films, the first barrier layer and the first base material layer have a diameter of about 30 to 300 μm by piercing a needle from the first barrier layer side. A wavelength conversion sheet for dark spot evaluation was prepared for each of Examples and Comparative Examples using a first optical film provided with a hole penetrating through. The pores are pseudo-reproductions of the pores created by the splash when the inorganic thin film layer is formed by thin film deposition. The obtained wavelength conversion sheet for dark spot evaluation was exposed to an environment having a temperature of 85 ° C. and a relative humidity of 0% RH. The wavelength conversion sheet for dark spot evaluation 72 hours, 200 hours, and 1000 hours after exposure is irradiated with blue light from the light emitting body protective film side having no holes, and from the light emitting body protective film side having holes. The transmitted light was visually confirmed, and the presence or absence of black spot-like defects (dark spots) was evaluated according to the following criteria. Tables 2 and 3 show the evaluation results of the dark spots around the holes together with the major axis a and the minor axis b of the holes provided in the first optical film.
A: The presence of dark spots was not confirmed even 1000 hours after exposure.
B: The presence of dark spots was not confirmed 200 hours after exposure, but the presence of dark spots was confirmed 1000 hours after exposure.
C: The presence of dark spots was not confirmed 72 hours after exposure, but the presence of dark spots was confirmed 200 hours after exposure.
D: The presence of dark spots was confirmed 72 hours after exposure.

In Example 2 and Reference Examples 1 and ^{3 in which} the oxygen permeability of the adhesive layer was 1000 cm ³ / (m ² · day · atm) or less, the presence of dark spots was not confirmed even after exposure to a high temperature environment for 1000 hours. .. In contrast, the oxygen permeability of the adhesive layer is ^{2000cm 3 / (m 2 · day} · atm) dark spots even after Comparative Examples 1 to 3 a relatively brief exposure exceeds was confirmed.

(Dark spot evaluation)
The wavelength conversion sheet using the illuminant protective film obtained in Examples and Comparative Examples was cut into a size of 60 cm × 34 cm (corresponding to a 27-inch monitor) and exposed to an environment at a temperature of 85 ° C. and a relative humidity of 0% for 1000 hours. did. After exposure, UV light was applied and the number of dark spots was visually counted. The number of dark spots is shown in Table 4.

From Table 4, dark spots were generated in Comparative Examples 1 to 3 in which the oxygen permeability of the adhesive layer was high, whereas dark spots were not observed in Examples.

10 ... Luminescent protective film, 11a ... First base material layer, 11b ... Second base material layer, 12a ... First inorganic thin film layer, 12b ... Second inorganic thin film layer, 13a ... First gas barrier coating layer, 13b ... Second gas barrier coating layer, 14a ... first barrier layer, 14b ... second barrier layer, 15 ... adhesive layer, 16a ... first optical film, 16b ... second optical film, 20 ... wavelength conversion sheet, 21 ... phosphor Layer, 22 ... second protective film, 23 ... defect, 24 ... dark spot, 30 ... backlight unit, 50 ... electroluminescence light emitting unit.

Claims (2)

A wavelength conversion sheet comprising two light emitting body protective films and a phosphor layer arranged between the two light emitting body protective films.
Both of the above two light emitting body protective films are light emitting body protective films in which the first optical film and the second optical film are bonded together via an adhesive layer formed of an acrylic adhesive .
The first optical film is an optical barrier film including a first base material layer and a first barrier layer formed on the first base material layer.
The second optical film is an optical barrier film including a second base material layer and a second barrier layer formed on the second base material layer.
The oxygen permeability of the adhesive layer is 1000 cm ³ / (m ² · day · atm) or less at a thickness of 5 μm.
The first optical film and the second optical film are bonded to each other via the adhesive layer so that the first barrier layer and the second barrier layer face each other.
The phosphor layer is a wavelength conversion sheet formed on the first optical film of the two illuminant protective films so that the first optical film is in contact with the phosphor layer. The first barrier layer includes a first inorganic thin film layer and a first gas barrier coating layer.
The wavelength conversion sheet according to claim 1, wherein the second barrier layer includes a second inorganic thin film layer and a second gas barrier coating layer.

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