JP6957876B2 - Light wavelength conversion member, backlight device, and image display device - Google Patents

Description

The present invention relates to an optical wavelength conversion member, a backlight device, and an image display device.

A transmissive image display device such as a liquid crystal display device is generally arranged on the back side of a transmissive image display panel such as a liquid crystal display panel, and includes a backlight device that illuminates the transmissive image display panel.

Currently, in order to improve color reproducibility, it is being studied to incorporate an optical wavelength conversion member containing quantum dots into an image display device (see, for example, Patent Document 1). Quantum dots can absorb light (primary light) and emit light of different wavelengths (secondary light). The wavelength of light emitted by a quantum dot mainly depends on the particle size of the quantum dot. Therefore, in an image display device incorporating an optical wavelength conversion member, various colors can be reproduced while using a light source that projects light in a single wavelength range. For example, when a light source that emits blue light is used, the light wavelength conversion member can absorb the blue light and emit green light and red light. An image display device incorporating such an optical wavelength conversion member has excellent color purity and therefore has excellent color reproducibility.

In the light wavelength conversion member, the quantum dots are deteriorated by moisture and oxygen, and the luminous efficiency may be lowered. Therefore, in an optical wavelength conversion sheet which is a form of an optical wavelength conversion member and includes an optical wavelength conversion layer containing quantum dots, barriers for suppressing the transmission of water and oxygen on both sides of the optical wavelength conversion layer A film is provided. Since the barrier film is provided so as to sandwich the light wavelength conversion layer, the conventional light wavelength conversion sheet has a structure in which the barrier film, the light wavelength conversion layer, and the barrier film are laminated in this order.

Japanese Unexamined Patent Publication No. 2015-11518

However, a heat resistance test in which a light wavelength conversion sheet having a structure in which barrier films are provided on both sides of the light wavelength conversion layer is left in an environment of 80 ° C. for 500 hours and a heat resistance test in which the light wavelength conversion layer is left in an environment of 60 ° C. and a relative humidity of 90% for 500 hours. When the moisture and heat resistance test is performed, there is a problem that the quantum dots deteriorate and the brightness decreases, especially at the peripheral edge of the optical wavelength conversion sheet or the point-like defects such as pinholes and cracks in the barrier film. be.

The present inventors use light wavelength conversion particles in which quantum dots are encapsulated in light-transmitting particles capable of improving heat resistance and moist heat resistance, in place of the barrier film or together with the barrier film. It has been found that the light wavelength conversion efficiency is lowered while the deterioration of the light wavelength can be suppressed.

The present invention has been made to solve the above problems. That is, a light wavelength conversion member having excellent heat resistance and moisture heat resistance and capable of improving the light wavelength conversion efficiency, a backlight device provided with such a light wavelength conversion member, and an image display device are provided. The purpose is.

As a result of diligent research on the above problems, the present inventors have found that when the refractive index of the surface of the light wavelength conversion particles is made larger than the refractive index of the binder resin, the light wavelength conversion efficiency is increased. .. The present invention has been completed based on such findings.

According to one aspect of the present invention, it is an optical wavelength conversion member including at least an optical wavelength conversion unit, in which the optical wavelength conversion unit is dispersed in a binder resin and the binder resin, and a quantum dot and the quantum dot. The refractive index of the surface of the light wavelength conversion particles is larger than that of the binder resin. A light wavelength conversion member is provided.

In the light wavelength conversion member, the light transmissive particles are resin particles containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and a carboxylic acid, and the light wavelength conversion. The material constituting the surface of the particles may be the resin constituting the resin particles.

In the light wavelength conversion member, the light wavelength conversion unit may be a light wavelength conversion layer, and the light wavelength conversion member may be a light wavelength conversion sheet.

In the light wavelength conversion member, the quantum dots form a core made of a first semiconductor compound, a shell made of a second semiconductor compound covering the core and different from the first semiconductor compound, and a surface of the shell. It may contain a ligand bound to.

In the light wavelength conversion member, the light wavelength conversion unit may further contain light scattering particles.

In the optical wavelength conversion member, 40 ° C., water vapor transmission rate at a relative humidity of 90% 0.1g ^/ (m 2 · 24h) or higher and 23 ° C., the oxygen permeability at a relative humidity of 90% 0.1 cm ³ / ^(m 2 · 24h · atm) or more may satisfy the at least one.

The light wavelength conversion member may further include an optical member arranged on at least one surface side of the light wavelength conversion unit and integrated with the light wavelength conversion unit.

According to another aspect of the present invention, there is provided a backlight device including a light emitting body and the above-mentioned light wavelength conversion member that receives light from the light emitting body.

According to another aspect of the present invention, there is provided an image display device including the above-mentioned light wavelength conversion member or the above-mentioned backlight device.

According to one aspect of the present invention, since the refractive index of the surface of the light wavelength conversion particles is larger than the refractive index of the binder resin, the light wavelength conversion efficiency can be improved. Further, since the light-transmitting particles have a function of suppressing the deterioration of the quantum dots, it is possible to obtain a light wavelength conversion member having excellent heat resistance and moisture heat resistance. According to another aspect of the present invention, it is possible to provide a backlight device including such a light wavelength conversion member, and an image display device.

It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows the operation of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. FIG. 5 is a cross-sectional view taken along the line I-I of the optical wavelength conversion sheet of FIG. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the image display device including the backlight device which concerns on embodiment. It is a perspective view of the lens sheet shown in FIG. FIG. 2 is a cross-sectional view taken along the line II-II of the lens sheet of FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown in FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is an enlarged view near the light entry surface of the optical plate shown in FIG. It is a figure shown schematically.

Hereinafter, the light wavelength conversion member, the backlight device, and the image display device according to the embodiment of the present invention will be described with reference to the drawings. In the present specification, terms such as "sheet" and "film" are not distinguished from each other based only on the difference in designation. Therefore, for example, "sheet" is used to include a member that can also be called a film, and "film" is used to include a member that can also be called a sheet. FIG. 1 is a schematic configuration diagram of an optical wavelength conversion sheet according to the present embodiment, FIG. 2 is a diagram showing the operation of the optical wavelength conversion sheet according to the present embodiment, and FIGS. 3 to 5, 7, and 8 show the operation of the optical wavelength conversion sheet. Is a schematic configuration diagram of another light wavelength conversion sheet according to the present embodiment, FIG. 6 is a cross-sectional view of the light wavelength conversion sheet of FIG. 5 along the line I-I, and FIGS. 9 and 10 show the present embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on a form.

<<< Light wavelength conversion member >>>
The light wavelength conversion member includes a light wavelength conversion unit including a binder resin and light wavelength conversion particles dispersed in the binder resin. The light wavelength conversion particles include quantum dots and light-transmitting particles that enclose the quantum dots and have a function of suppressing deterioration of the quantum dots. In the light wavelength conversion unit, the refractive index of the surface of the light wavelength conversion particles is larger than the refractive index of the binder resin.

As used herein, the term "light transmissive" means having the property of transmitting light, and "light transmissive" also includes transparency. In the present invention, since the quantum dots are included in the light-transmitting particles, if the light emission from the quantum dots emitted from the optical wavelength conversion sheet can be confirmed, the particles surrounding the quantum dots are considered to have light-transmitting properties. I can say. The emission of quantum dots can be confirmed using a fluorometer.

Whether or not the light-transmitting particles have a function of suppressing the deterioration of quantum dots is determined by conducting a heat resistance test and a moist heat resistance test on the light wavelength conversion member, and the brightness after the heat resistance test with respect to the brightness before the heat resistance test. It can be judged by measuring the maintenance rate of the brightness after the moisture resistance test and the maintenance rate of the brightness after the moisture resistance test with respect to the brightness before the moisture resistance test. Specifically, the light wavelength conversion member is subjected to a heat resistance and moist heat resistance test according to the procedure and conditions described in the column of Examples of the present specification, and the brightness after the heat resistance test is compared with the brightness before the heat resistance test. If both the maintenance rate and the brightness maintenance rate after the moisture resistance test are 80% or more with respect to the brightness before the moisture resistance test, it can be said that the light-transmitting particles have a function of suppressing the deterioration of the quantum dots. Further, "refractive index" in the present specification means a refractive index at a wavelength of 550 nm unless otherwise specified.

The light wavelength conversion member may be a light wavelength conversion sheet, a light source, an optical plate, or a color filter. In FIG. 1, a light wavelength conversion sheet 10 as an example of a light wavelength conversion member is shown. In this case, the light wavelength conversion unit is the light wavelength conversion layer 11. Needless to say, the contents described in the light wavelength conversion sheet 10 and the light wavelength conversion layer 11 are also applied to the light wavelength conversion member and the light wavelength conversion unit.

<<< Light wavelength conversion sheet >>>
The light wavelength conversion sheet 10 shown in FIG. 1 is a form of a light wavelength conversion member, which converts the wavelength of a part of the incident light into another wavelength, and the other part of the incident light and the other part of the incident light. It is a sheet that emits wavelength-converted light. The light wavelength conversion sheet 10 shown in FIG. 1 includes a light wavelength conversion layer 11, light transmitting base materials 12 and 13 provided on both sides of the light wavelength conversion layer 11, and light in the light transmitting base materials 12 and 13. It includes light diffusion layers 14 and 15 provided on the side opposite to the surface on the wavelength conversion layer 11 side.

In the light wavelength conversion sheet 10, the surfaces of the light diffusion layers 14 and 15 constitute the surfaces 10A and 10B of the light wavelength conversion sheet 10. The light wavelength conversion sheet 10 includes the light-transmitting base materials 12 and 13, but does not have a barrier layer, so that it does not have a barrier film composed of the light-transmitting base material and the barrier layer. The light wavelength conversion sheet 10 has a structure of a light diffusion layer 14 / a light transmission base material 12 / a light wavelength conversion layer 11 / a light transmission base material 13 / a light diffusion layer 15, but is a light wavelength conversion layer. The structure of the optical wavelength conversion sheet is not particularly limited as long as it has.

In the optical wavelength conversion sheet 10, as shown in FIG. 2, when light is incident from the surface 10A of the optical wavelength conversion sheet 10, the light incident on the quantum dots 18 described later in the optical wavelength conversion layer 11 L1 is converted into light L2 having a wavelength different from that of light L1 and emitted from the surface 10B. On the other hand, even when light is incident from the surface 10A, the light L1 passing between the quantum dots 18 in the optical wavelength conversion layer 11 is emitted from the surface 10B without being wavelength-converted.

In the light wavelength conversion sheet 10, excellent heat resistance and moisture heat resistance can be obtained by the light wavelength conversion particles 17 of the light wavelength conversion layer 11, so that the entire sheet has a water vapor transmittance (WVTR) at 40 ° C. and 90% relative humidity. : Water Vapor Transmission Rate) may be a 0.1g ^/ (m 2 · 24h) or more. The water vapor permeability is a numerical value obtained by a method based on JIS K7129: 2008. The water vapor transmission rate can be measured using a water vapor transmission rate measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON). The water vapor transmittance is the average value of the values obtained by measuring three times. Since a barrier film is formed on the conventional light wavelength conversion sheet, the light wavelength conversion sheet 10 has a higher water vapor transmission rate than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher water vapor transmission rate. Moisture is more easily transmitted than the conventional light wavelength conversion sheet. As will be described later, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the water vapor transmittance is the water vapor transmittance of the entire light wavelength conversion sheet including the optical member.

In the light wavelength conversion sheet 10, excellent heat resistance and moisture heat resistance can be obtained by the light wavelength conversion particles 17 of the light wavelength conversion layer 11, so that the entire sheet has an oxygen transmittance (OTR) at 23 ° C. and 90% relative humidity. : Oxygen Transmission Rate) may be a ^{0.1cm 3 / (m 2 · 24h} · atm) or more. The light wavelength conversion sheet 10 may satisfy the water vapor transmittance and the oxygen transmittance at the same time. The oxygen permeability is a numerical value obtained by a method based on JIS K7126: 2006. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON). The oxygen permeability shall be the average value of the values obtained by measuring three times. Since a barrier film is formed on the conventional light wavelength conversion sheet, the light wavelength conversion sheet 10 has a higher oxygen transmission rate than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher oxygen transmission rate. Compared to the conventional light wavelength conversion sheet, not only water but also oxygen is easily transmitted. Similarly to the above, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the oxygen transmittance is the oxygen transmittance of the entire light wavelength conversion sheet including the optical member.

40 ° C. in the optical wavelength conversion sheet 10, a water vapor transmission rate of 90% relative humidity may be made with 1g ^/ (m 2 · 24h) or more and 23 ° C. in the optical wavelength conversion sheet 10, a relative humidity of 90% oxygen permeability may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

The thickness of the optical wavelength conversion sheet 10 is preferably 10 μm or more and 500 μm or less. When the average thickness of the optical wavelength conversion sheet 10 is within this range, it is suitable for reducing the weight and thinning of the backlight device.

The thickness of the light wavelength conversion sheet 10 is determined by photographing a cross section of the light wavelength conversion sheet 10 using a scanning electron microscope (SEM) and measuring the thickness of the light wavelength conversion sheet 10 at 20 points in the image of the cross section. The average value of the thickness at 20 points. Among these, considering that the film thickness of the optical wavelength conversion sheet 10 is on the order of μm, it is preferable to use SEM. When measuring the thickness of the optical wavelength conversion sheet 10 by SEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 1000 to 7000 times.

<< Optical wavelength conversion layer >>
The light wavelength conversion layer 11 includes a binder resin 16 and light wavelength conversion particles 17 dispersed in the binder resin 16. The light wavelength conversion layer 11 may further include light scattering particles 20 as shown in FIG. By including the light scattering particles 20, the light wavelength conversion efficiency can be further improved.

The refractive index of the surface of the light wavelength conversion particles 17 is larger than that of the binder resin 16. By making the refractive index of the surface of the light wavelength conversion particles 17 larger than the refractive index of the binder resin 16, the light incident on the light wavelength conversion layer 11 and traveling through the binder resin 16 is emitted from the surface of the light wavelength conversion particles 17. It is possible to suppress total reflection. The refractive index of the surface of the light wavelength conversion particles 17 may be larger than the refractive index of the binder resin 16, but specifically, it is preferably 1.4 or more and 1.8 or less. The lower limit of the refractive index of the surface of the light wavelength conversion particles 17 is more preferably 1.5 or more, and the upper limit is preferably 1.7 or less. Further, the difference in refractive index between the material constituting the surface of the light wavelength conversion particles 17 and the binder resin 16 is preferably 0.05 or more and 0.3 or less, and 0.1 or more and 0.25 or less. Is more preferable.

Regarding the refractive index of the binder resin 16, for example, 10 pieces of the binder resin 16 are taken out from the light wavelength conversion layer 11 by cutting out or the like, and the refractive index of the binder resin 16 is measured by the Becke method in each of the 10 pieces taken out. Then, it can be obtained as an average value of 10 refractive indexes of the measured binder resin 16. Further, the refractive index of the surface of the light wavelength conversion particle 17 is determined by, for example, taking out a fragment from the binder resin 16 in which a part of the surface of the light wavelength conversion particle 17 is exposed by cutting out from the light wavelength conversion layer 11 and taking out the fragment. In the above, the refractive index of the surface of the 10 light wavelength conversion particles 17 whose surfaces are exposed by the Becke method can be measured, and can be obtained as the average value of the 10 surface refractive indices of the measured light wavelength conversion particles 17. .. In the Becke method, a refractive index standard solution having a known refractive index is used, the fragment is placed on a slide glass or the like, the refractive index standard solution is dropped onto the sample, and the fragment is immersed in the refractive index standard solution. Observe the situation by microscopic observation, and visually observe the emission lines (Becke lines) generated on the surface of the binder resin and the light wavelength conversion particles due to the difference in the refractive index between the surface of the binder resin and the light wavelength conversion particles and the refractive index of the refractive index standard solution. Refractive index that cannot be achieved This is a method in which the refractive index of the standard liquid is used as the refractive index of the surface of the binder resin or the light wavelength conversion particles. When the surface of the light wavelength conversion particles is not exposed in the removed pieces, the surface of the light wavelength conversion particles is covered with the binder resin, so that the binder resin existing around the light wavelength conversion particles is used. There is no difference in refractive index. Therefore, it is possible to determine whether or not a part of the surface of the light wavelength conversion particles is exposed by measuring the difference in refractive index with the binder resin existing around the light wavelength conversion particles by the Becke method or the like. .. If you only want to check whether the refractive index of the surface of the optical wavelength conversion particle 17 is larger than the refractive index of the binder resin 16, a phase-shift laser interference microscope (Phase-shift laser interference microscope manufactured by FK Optical Laboratory or Mizojiri) It is also possible to make a judgment using a two-beam interference microscope manufactured by Optical Industry Co., Ltd.).

When the light-transmitting particles 19 described later included in the light wavelength conversion particles 17 are resin particles, in the light wavelength conversion layer 11, sulfur in the light wavelength conversion layer 11 measured by fluorescence X-ray analysis (XRF), The content of one or more elements selected from the group consisting of phosphorus and nitrogen (hereinafter, this element is referred to as "specific element") is preferably 0.5% by mass or more. When the content of the specific element is 0.5% by mass or more, the deterioration of the quantum dots can be further suppressed. The content of a specific element can be measured by using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). The lower limit of the content of the specific element in the optical wavelength conversion layer 11 measured by fluorescent X-ray analysis (XRF) is more preferably 1% by mass or more, and the upper limit of the content of the specific element is 20% by mass. It is more preferably% or less, and further preferably 10% by mass or less. If the content of a specific element exceeds 20% by mass, sufficient curing may not be performed when the light wavelength conversion layer is formed.

The film thickness of the optical wavelength conversion layer 11 is preferably 10 μm or more and 200 μm or less. When the average thickness of the light wavelength conversion layer 11 is within this range, it is suitable for reducing the weight and thinning of the backlight device. For the film thickness of the light wavelength conversion layer 11, a cross section of the light wavelength conversion layer 11 is photographed using a scanning electron microscope (SEM), and the film thickness of the light wavelength conversion layer 11 is measured at 20 points in the image of the cross section. , The average value of the film thickness at the 20 points. The upper limit of the average film thickness of the optical wavelength conversion layer 11 is more preferably less than 170 μm.

<Binder resin>
The refractive index of the binder resin 16 may be 1.3 or more and 1.7 or less. The binder resin 16 is not particularly limited as long as the refractive index is smaller than the refractive index on the surface of the light wavelength conversion particles 17, but the material constituting the surface of the light wavelength conversion particles 17 is an epoxy resin (refractive index: 1. In the case of 55 to 1.60), it is preferably a (meth) acrylic resin (refractive index: about 1.5) or a silicone resin (refractive index: 1.40 to 1.45), and light wavelength conversion. When the material constituting the surface of the particles is an epoxy resin (refractive index: 1.55 to 1.60) or a (meth) acrylic resin (refractive index: about 1.5), a silicone resin (refractive index: about 1.5) It is preferably 1.40 to 1.45).

((Meta) acrylic resin)
The (meth) acrylic resin is a resin composed of a polymer of a (meth) acrylate-based compound. As used herein, the term "(meth) acrylate" is meant to include both "acrylate" and "methacrylate". Examples of the (meth) acrylate-based compound include (meth) acrylate monomers, oligomers, and prepolymers, which can be appropriately adjusted and used.

Examples of the (meth) acrylate monomer include a monomer containing a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, and ethylene glycol di (meth) acrylate. , Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, trimethyl propantri (meth) acrylate, trimethylol ethanetri (meth) ) Acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerol (meth) acrylate And so on.

As the (meth) acrylate oligomer, a bifunctional or higher polyfunctional oligomer having two or more (meth) acryloyl groups is preferable, and a trifunctional or higher multifunctional oligomer is more preferable. Examples of the polyfunctional oligomer include polyester (meth) acrylate, urethane (meth) acrylate, polyester-urethane (meth) acrylate, polyether (meth) acrylate, polyol (meth) acrylate, melamine (meth) acrylate, and isocyanurate. Examples thereof include (meth) acrylate and epoxy (meth) acrylate.

The (meth) acrylate prepolymer has a weight average molecular weight of more than 10,000, and the weight average molecular weight is preferably 10,000 or more and 80,000 or less, and more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained light wavelength conversion member may be deteriorated. Therefore, when a (meth) acrylate prepolymer having a weight average molecular weight of more than 80,000 is used, it is preferable to mix and use the above-mentioned monomer and the above-mentioned oligomer. Examples of the polyfunctional (meth) acrylate prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

(Silicone resin)
The silicone resin is a resin having a siloxane bond. Examples of the silicone resin include an addition reaction type silicone resin, a polycondensation reaction type silicone resin, and an ultraviolet curable silicone resin. Examples of the addition reaction type silicone resin include those obtained by heat-curing polydimethylsiloxane and hydrogensiloxane containing a terminal vinyl group under a platinum catalyst or a rhodium catalyst. Examples of the polycondensation reaction type silicone resin include those obtained by heating and curing polydimethylsiloxane and hydrogensiloxane containing a hydroxyl group at the terminal using an organic tin catalyst. Examples of the ultraviolet curable silicone resin include an addition reaction type in which vinylsiloxane is hydrosilylated in the presence of a platinum catalyst, and a radical addition type in which a siloxane containing an alkenyl group and a siloxane containing a mercapto group are cured using a photopolymerization catalyst. Examples thereof include a cation polymerization type in which an epoxy radical is photo-opened with an onium salt initiator and cured.

<Light wavelength conversion particles>
The light wavelength conversion particle 17 includes a quantum dot 18 and a light transmissive particle 19 that encloses the quantum dot 18 and has a function of suppressing deterioration of the quantum dot. The material constituting the surface of the light wavelength conversion particles 17 shown in FIG. 1 is a material constituting the light transmissive particles 19. The light wavelength conversion particles may further include a coat layer that covers the surface of the light transmissive particles. When the light wavelength conversion particles include a coat layer, the material constituting the surface of the light wavelength conversion particles is a resin constituting the coat layer.

When the light transmissive particles 19 are resin particles, the content of the specific element in the light wavelength conversion particles 17 measured by fluorescent X-ray analysis (XRF) in the light wavelength conversion particles 17 is 0.5 mass. It is preferably% or more. By setting the content of a specific element to 0.5% by mass or more, deterioration of quantum dots can be reliably suppressed. The content of the specific element is taken as the average value obtained by measuring the content of the specific element in 20 light wavelength conversion particles. The content of a specific element can be measured by using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). The lower limit of the content of the specific element in the light wavelength conversion particles 17 measured by X-ray fluorescence analysis (XRF) is more preferably 1% by mass or more, and the upper limit of the content of the specific element is 20% by mass. It is more preferably% or less, and further preferably 10% by mass or less. By setting the content of the specific element to 20% by mass or less, sufficient curing can be performed at the time of forming the light wavelength conversion particles. When the light wavelength conversion particles contain two or more specific elements, the above-mentioned content means the total content of the specific elements.

The average particle size of the light wavelength conversion particles 17 is preferably 10 μm or less. By setting the average particle size of the light wavelength conversion particles 17 to 10 μm or less, the dispersibility is improved. The lower limit of the average particle size of the light wavelength conversion particles 17 is preferably 0.5 μm or more from the viewpoint of the extraction efficiency of the light wavelength conversion particles 17 and the difficulty of agglomeration of the particles. The average particle size of the light wavelength conversion particles 17 can be obtained by measuring the particle size of 20 light wavelength conversion particles in the observation of the light wavelength conversion particles with a scanning electron microscope (SEM) and calculating the average value thereof. can.

The shape of the light wavelength conversion particles 17 is not particularly limited, and is, for example, spherical (true spherical, substantially true spherical, elliptical spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate, flaky, indefinite. The shape and the like can be mentioned. When the shape of the light wavelength conversion particles 17 is not spherical, the particle size of the light wavelength conversion particles 17 is a true spherical particle size having the same volume.

It is preferable that each of the light wavelength conversion particles 17 contains one or more quantum dots 18. By setting the number of quantum dots contained in one light wavelength conversion particle to one or more, it is possible to suppress a decrease in brightness. The number of quantum dots contained in one light wavelength conversion particle is 100,000 to 500,000 times the cross section of 20 light wavelength conversion particles at random using a transmission electron microscope or a scanning transmission electron microscope. The number of quantum dots contained in one light wavelength conversion particle is calculated from the obtained cross-sectional image, and the average value of the calculated number of quantum dots is calculated.

Each light wavelength conversion particle 17 contains two or more quantum dots 18, and the average distance between the quantum dots 18 in the quantum dots 18 included in one light wavelength conversion particle 17 is 1 nm or more. Is preferable. By setting the average distance between the quantum dots to 1 nm or more, concentration quenching that causes quenching due to energy transfer between the quantum dots is less likely to occur, so that a decrease in luminous efficiency can be suppressed. The average distance between the quantum dots was obtained by randomly photographing the cross sections of 20 light wavelength-converted particles with a transmission electron microscope or a scanning transmission electron microscope at a magnification of 100,000 to 500,000 times. The distance between the quantum dots is calculated from the image of, and the average value of the calculated distances between the quantum dots is calculated. It is more preferable that the upper limit of the average distance between the quantum dots 18 in the quantum dots 18 is 100 nm or less.

<Quantum dot>
The quantum dots 18 are nano-sized semiconductor particles having a quantum confinement effect. The particle size and the average particle size of the quantum dots 18 are, for example, 1 nm or more and 20 nm or less. When the quantum dot 18 absorbs light from an excitation source and reaches an energy excited state, the quantum dot 18 emits energy corresponding to the energy band gap of the quantum dot 18. Therefore, by adjusting the particle size or the composition of the substance of the quantum dots 18, the energy band gap can be adjusted, and energy in various levels of wavelength bands can be obtained. In particular, the quantum dots 18 can generate strong fluorescence in a narrow wavelength band.

Specifically, the energy band gap of the quantum dots 18 increases as the particle size decreases. That is, as the crystal size becomes smaller, the emission of the quantum dots shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle size of the quantum dot 18, the emission wavelength can be adjusted over the entire wavelength of the spectrum in the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dot 18 is composed of CdSe / ZnS described later, when the particle diameter of the quantum dot 18 is 2.0 nm or more and 4.0 nm or less, blue light is emitted and the particle diameter of the quantum dot 18 is large. When the particle size is 3.0 nm or more and 6.0 nm or less, green light is emitted, and when the particle size of the quantum dots 18 is 4.5 nm or more and 10.0 nm or less, red light is emitted. In the present specification, "blue light" is light having a wavelength range of 380 nm or more and less than 480 nm, "green light" is light having a wavelength range of 480 nm or more and less than 590 nm, and "red light" is Light having a wavelength range of 590 nm or more and 750 nm or less. In the above, the range of the particle size of the quantum dot that emits blue light and the particle size of the quantum dot that emits green light partially overlaps, and the particle size of the quantum dot that emits green light and the red light are used. The range of the particle size of the emitted quantum dots overlaps in part, but even if the quantum dots have the same particle size, the emission color may differ depending on the size of the core of the quantum dots, so there is no contradiction. It's not something to do. The average particle size of the quantum dots 18 is determined by measuring the particle size of 20 quantum dots in cross-sectional observation of the light wavelength converted particles with a transmission electron microscope or a scanning transmission electron microscope and calculating the average value thereof. do.

As the quantum dots 18, one type of quantum dots may be used, but it is also possible to use two or more types of quantum dots, each of which has an emission band in a single wavelength range, depending on the particle size or material. be. The quantum dots 18 shown in FIGS. 1 and 2 are composed of a first quantum dot 18A and a second quantum dot 18B having an emission band in a wavelength range different from that of the first quantum dot 18A. There is.

The quantum dots 18 can generate strong fluorescence in a desired narrow wavelength range. Therefore, the backlight device using the light wavelength conversion sheet can illuminate the display panel with the light of the three primary colors having excellent color purity. In this case, the display panel will have excellent color reproducibility.

The quantum dots 18 are composed of, for example, a core made of a first semiconductor compound, a shell made of a second semiconductor compound covering the core and different from the first semiconductor compound, and a ligand bound to the surface of the shell. It is configured.

Examples of the first semiconductor compound constituting the core include MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, II-VI semiconductor compounds such as HgS, HgSe and HgTe, III such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs and TiSb Examples thereof include semiconductor compounds such as -V semiconductor compounds, IV semiconductors such as Si, Ge and Pb, and semiconductor crystals containing semiconductors. Further, a semiconductor crystal containing a semiconductor compound containing three or more elements such as InGaP can also be used. Among these, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferable from the viewpoints of ease of fabrication, controllability of particle size capable of obtaining light emission in the visible range, and the like.

As the second semiconductor compound constituting the shell, it is preferable to use a semiconductor compound having a bandgap higher than that of the first semiconductor compound constituting the core so that excitons are confined in the core. As a result, the luminous efficiency of the quantum dots can be increased. Examples of the second semiconductor compound constituting the shell include ZnS, ZnSe, CdS, GaN, CdSSe, ZnSeTe, AlP, ZnSTe, ZnSSe and the like.

Specific combinations of the core-shell structure (core / shell) consisting of the core and the shell include, for example, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, Gap / ZnS, Si / ZnS, and the like. InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InP / ZnSSe, InGaP / ZnSTe, InGaP / ZnSSe and the like can be mentioned.

The ligand is for stabilizing unstable quantum dots. Examples of the ligand include sulfur compounds such as thiols, phosphorus compounds such as phosphine compounds or phosphine oxides, nitrogen compounds such as amines, and carboxyl group-containing compounds.

The shape of the quantum dots 18 is not particularly limited, and may be, for example, spherical, rod-shaped, disk-shaped, or other shapes. When the shape of the quantum dot is not spherical, the particle size of the quantum dot 18 can be a true spherical value having the same volume.

Information such as the particle size, average particle size, shape, and dispersed state of the quantum dots 18 can be obtained by a transmission electron microscope or a scanning transmission electron microscope. Further, since the emission color of the quantum dot 18 changes depending on the particle size, it is also possible to obtain the particle size of the quantum dot by confirming the emission color of the quantum dot 18. Further, the crystal structure and crystallite size of the quantum dots 18 can be known by X-ray crystal diffraction (XRD). Furthermore, information on the particle size and the like of the quantum dots 18 can be obtained from the ultraviolet-visible (UV-Vis) absorption spectrum.

<Light-transmitting particles>
The light-transmitting particles 19 have a function of suppressing deterioration of the quantum dots 18. The light-transmitting particles 19 may be either resin particles containing at least one of the above-mentioned specific element and carboxylic acid, or barrier particles having a barrier property that suppresses the permeation of water and oxygen, but have excellent flexibility. Resin particles are preferable from the viewpoint of having properties and preventing defects due to cracks from occurring.

When the light-transmitting particles 19 are resin particles, examples of the resin constituting the resin particles include an epoxy resin and a (meth) acrylic resin.

(Epoxy resin)
The epoxy resin is a resin obtained by reacting an epoxy compound with a curing agent, or a resin obtained by polymerizing epoxy compounds with each other by the action of a catalytic curing agent. As used herein, the term "epoxy compound" is a concept that also includes an epoxy resin before reaction or polymerization.

An epoxy compound is a compound having one or more epoxy groups in the molecule. The epoxy compound is not particularly limited, but for example, bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, biphenyl type epoxy compound, fluorene type epoxy compound, novolacphenol type epoxy compound, cresol novolac type epoxy. Aromatic compounds such as compounds and modified products thereof, or alkylene glycol diglycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether or 1,6-hexanediol diglycidyl ether, glycerin or an alkylene oxide adduct thereof. Diglycidyl ether of polyhydric alcohol such as di or triglycidyl ether, diglycidyl ether of polyethylene glycol or its alkylene oxide adduct, polyalkylene glycol diglycidyl ether such as diglycidyl ether of polypropylene glycol or its alkylene oxide adduct, And aliphatic systems such as alkylene oxide. Here, examples of the alkylene oxide include aliphatic epoxy compounds such as ethylene oxide and propylene oxide, 3', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and 3,4-epoxycyclohexylmethylmethacrylate. Examples thereof include an alicyclic epoxy compound containing one or more epoxy groups and one or more ester groups in the molecule.

((Meta) acrylic resin)
Since the (meth) acrylic resin used for the resin particles is the same as the (meth) acrylic resin described in the column of binder resin, the description thereof will be omitted here.

When the light-transmitting particles 19 are resin particles, the resin particles contain at least one of a specific element and a carboxylic acid in order to suppress the deterioration of the quantum dots 18. At least one of a specific element and a carboxylic acid is a compound selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid (hereinafter, this compound is referred to as a "specific compound"). Can be included in the resin particles by using.

The specific element or carboxylic acid does not have to be fixed in the resin particles, but from the viewpoint of preventing the elution of the specific element or carboxylic acid, it is fixed in the resin particles 2 by bonding with the resin constituting the resin particles. Is preferable. When at least one of a specific element and a carboxylic acid is fixed to the resin constituting the resin particles, it is preferable that the specific compound has a polymerizable functional group. Examples of the polymerizable functional group include an ethylenically unsaturated group such as a (meth) acryloyl group, a vinyl group and an allyl group, an epoxy group, an isocyanate group, or a hydroxyl group. When at least one of the specific compound and the carboxylic acid contains an isocyanate group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particles contains a hydroxyl group, and the specific compound and the carboxylic acid When at least one of them contains a hydroxyl group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particles preferably contains an isocyanate group. When a specific compound contains a polymerizable functional group, it can be polymerized with the polymerizable compound, and at least one of a specific element and a carboxylic acid can be immobilized in the resin particles. When the specific compound contains a polymerizable functional group, the specific compound may contain one or more polymerizable functional groups, but may contain two or more.

Whether or not the resin particles contain a specific element or carboxylic acid can be confirmed as follows. First, as will be described later, a ligand composed of a sulfur-based compound, a phosphorus-based compound, a nitrogen-based compound, a carboxyl group-containing compound, or the like is bound to the surface of the quantum dot shell. Even when an element or carboxylic acid is detected, the detected specific element or carboxylic acid is not necessarily the specific element or carboxylic acid contained in the resin particles. On the other hand, the ligand of the quantum dot is bound to the surface of the shell, and the size of the coordination site of the ligand is usually within about 1 nm, so that the ligand does not exist at a position separated from the surface of the shell by 3 nm or more. Therefore, a specific element is detected by X-ray photoelectron spectroscopy (XPS) or energy dispersive X-ray analysis (EDS) at an arbitrary position on the surface or inside of the resin particle at a distance of 3 nm or more from the surface of the shell of the quantum dot. If carboxylic acid is detected by microinfrared spectroscopic analysis (IR), it can be determined that the resin particles contain a specific element or carboxylic acid.

<Specific compound>
The specific compound is one or more compounds selected from the group consisting of a sulfur-containing compound, a phosphorus-containing compound, a nitrogen-containing compound, and a carboxylic acid, and is a compound for suppressing deterioration of quantum dots.

(Sulfur-containing compound)
The sulfur-containing compound is a compound containing sulfur. The sulfur-containing compound is not particularly limited, and examples thereof include a thiol compound, a thioether compound, a disulfide compound, and a thiophene compound. When a thiol compound is used as the sulfur compound, it is preferable that the thiol compound and the polymerizable compound form a copolymer by a thiol-ene reaction in the resin particles. By copolymerizing the thiol compound and the polymerizable compound, the thiol compound can be fixed in the resin particles. When a thiol compound is used, it is preferable to use a primary thiol compound from the viewpoint of excellent curability by ionizing radiation or heat, but from the viewpoint of pot life at the time of coating and suppression of odor, secondary thiol is used. It is preferable to use a compound or a tertiary thiol compound.

The primary thiol compound refers to a compound in which one hydrocarbon group is bonded to carbon to which a thiol group is bonded. The secondary thiol compound is a compound in which two hydrocarbon groups are bonded to carbon to which a thiol group is bonded. The tertiary thiol compound refers to a compound in which three hydrocarbon groups are bonded to carbon to which a thiol group is bonded. The thiol compound may have one or more thiol groups in one molecule, but is preferably two or more from the viewpoint of improving the heat resistance and moisture heat resistance of the quantum dots.

式中、Ｒ^１は水素原子、置換されていてもよい炭素原子数１〜１０のアルキル基であり、Ｒ^２は置換されていてもよい炭素原子数１〜１０のアルキレン基であり、Ｒ^３は炭素原子以外の原子を含んでいてもよい炭素原子数１〜１５のｎ価の脂肪族基であり、ｍは１〜２０の整数であり、ｎは１〜３０の整数である。 The thiol compound is not particularly limited, but the compound represented by the following general formula (1) is preferable from the viewpoint of improving the curability when forming the light wavelength conversion layer, the heat resistance of the quantum dots, and the heat resistance to moisture and heat.

In the formula, R ¹ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be ^{substituted, and R 2} is an alkylene group having 1 to 10 carbon atoms which may be substituted, and R ³ Is an n-valent aliphatic group having 1 to 15 carbon atoms which may contain atoms other than carbon atoms, m is an integer of 1 to 20, and n is an integer of 1 to 30.

The alkyl group of R ¹ may be linear or branched. Examples of the alkyl group of R ¹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, tert-butyl group, n-pentyl group and neopentyl group. tert-pentyl group, isopentyl group, 2-methylbutyl group, 1-ethylpropyl group, hexyl group, isohexyl group, 4-methylpentyl group, 3-methylpentyl group, 2-methylpentyl group, 1-methylpentyl group, 3 , 3-dimethylbutyl group, 2,2-dimethylbutyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 1-ethylbutyl Examples thereof include a group, a 2-ethylbutyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group.

The alkylene group of R ² may be either linear or branched. Examples ^{of the alkylene group of R 2} include a methylene group, an ethylene group, a trimethylene group, a propylene group, an isopropylene group and the like.

When the alkyl group of ^{R 1 or the alkylene group of R 2} is substituted, the substituent includes a halogen atom, a hydroxyl group, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group, a phenyl group and the like. The groups to be selected are listed. Halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms.

One methylene group in the alkyl group of R ^{1 or the alkylene group of R 2} or two or more non-adjacent methylene groups are -O-, -S-, -SO _2- , -CO-, -COO-,-. ^{OCO -, - NR 4 -,} - CONR 4 -, - NR 4 CO -, - N = CH- and -CH = CH- may be substituted with at least one group selected from the group consisting of (formula Among them, R ⁴ independently represents hydrogen or an alkyl group having 1 to 5 carbon atoms.)

Examples of atoms other than carbon atoms that may be contained in the aliphatic group of R ^{3 include nitrogen atoms, oxygen atoms, sulfur atoms and the like.}

Of these, an alkyl group having 1 to 5 carbon atoms in which ^{R 1} may be substituted is an alkyl group from the viewpoint of curability during formation of light wavelength conversion particles and improvement of heat resistance and moist heat resistance of quantum dots. R ² is an alkylene group having 1 to 5 carbon atoms which may be substituted, R ³ is an aliphatic group having 1 to 10 carbon atoms, m is 1 to 10, and n is 1 to 15. A primary thiol compound or a secondary thiol compound is preferable. One methylene group in the alkylene group of R ² or two or more non-adjacent methylene groups may be substituted with the same group as described above.

Specific examples of the primary thiol compound include hexanedithiol, decandithiol, ethylene glycol bisthioglycolate, 1,4-butanediol bisthioglycolate, trimethylolpropanetristhioglycolate, pentaerythritol tetrakisthioglycolate, and ethylene. Glycerol bis (3-mercaptopropionate), 1,2-propylene glycol bis (3-mercaptopropionate), 1,3-propylene glycol bis (3-mercaptopropionate), 1,4-butanediol bis (3-Mercaptopropionate), Glycerintris (3-Mercaptopropionate), Trimethylolpropanthris (3-Mercaptopropionate), Trimethylolethanetris (3-Mercaptopropionate), Pentaerythritol tetrakis (3-mercaptopropionate) 3-Mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate) and the like.

Specific examples of the secondary thiol compound include 1,4-bis (3-mercaptobutylyloxy) butane and 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2. , 4,6 (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptobutyrate), trimethylolethane ethanetris (3-mercaptobutyrate), etc. Can be mentioned. Specific examples of the tertiary thiol compound include tert-butyl mercaptan and the like.

式中、ｑは０または１の整数であり、Ｒ^５〜Ｒ^７は、それぞれ独立して、水素、水酸基、置換されていてもよい炭素原子数１〜３０の直鎖または分岐のアルキル基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルコキシ基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルケニル基、置換されていてもよい炭素数１〜３０の直鎖または分岐のアルキニル基、置換されていてもよい炭素数３〜６のシクロアルキル基、置換されていてもよいフェニル基、置換されていてもよいビフェニル基、置換されていてもよいナフチル基、置換されていてもよいフェノキシ基、または置換されていてもよい複素環基、または水酸基を表す。 (Phosphorus-containing compound)
The phosphorus-containing compound is a compound containing phosphorus. The phosphorus-containing compound is not particularly limited, and examples thereof include a phosphonic acid compound, a phosphinic acid compound, a phosphine oxide compound, a phosphonic acid compound, a phosphinic acid compound, and a phosphine compound. Among these, the compound represented by the following general formula (2) is preferable from the viewpoint of improving the curability at the time of forming the light wavelength conversion particles and the heat resistance and moisture heat resistance of the quantum dots.

In the formula, q is an integer of 0 or 1, and R ^{5 to} R ⁷ are independently hydrogen, hydroxyl group, or a linear or branched alkyl group having 1 to 30 carbon atoms which may be substituted. A linear or branched alkoxy group having 1 to 30 carbon atoms which may be substituted, a linear or branched alkenyl group having 1 to 30 carbon atoms which may be substituted, and a linear or branched alkenyl group having 1 to 30 carbon atoms which may be substituted. 30 linear or branched alkynyl groups, optionally substituted cycloalkyl groups having 3 to 6 carbon atoms, optionally substituted phenyl groups, optionally substituted biphenyl groups, optionally substituted Represents a naphthyl group, an optionally substituted phenoxy group, or an optionally substituted heterocyclic group, or a hydroxyl group.

When ^{any of R 5 to} R ⁷ has a substituent, the substituent includes a halogen atom (F, Cl, Br), an alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 6 carbon atoms. , An alkenyl group having 1 to 6 carbon atoms, an alkynyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, a (meth) acryloyl group, a (meth) acryloyloxy group, an amino group, a hydroxyl group, a carboxyl group, Examples thereof include an alkylamino group having 1 to 6 carbon atoms, a nitro group, a phenyl group, a biphenyl group, a naphthyl group, a phenoxy group, a heterocyclic group and the like.

Heterocyclic groups include pyridyl group, pyrimidinyl group, pyridadyl group, pyrazole group, frill group, thienyl group, oxazolyl group, isoxazolyl group, oxadiazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, triazolyl group, pyrrole group and pyrazolyl group. , Or a tetrazolyl group.

Specific examples of the phosphorus compound include tris (2-ethylhexyl) phosphine, trilaurylphosphine, tris (tridecyl) phosphine, bis (decyl) pentaerythritol diphosphite, and bis (tridecyl) pentaerythritol diphosphite. , Triphenylphosphine, Trisnonylphenylphosphine, Butyl acid phosphate, Oleyl acid phosphate, Tetracosyl acid phosphate, 2-Hydroxyethyl methacrylate acid phosphate, Dibutyl phosphate, dimethyl vinyl phosphate, Di-2-ethylhexyl hydrozen phosphate , Georail Hydrozenphosphite and the like.

(Nitrogen-containing compound)
The nitrogen-containing compound is a compound containing nitrogen. The nitrogen-containing compound is not particularly limited, but an amine compound is preferable from the viewpoint of curability at the time of forming light wavelength conversion particles and improvement of heat resistance and moisture heat resistance of quantum dots. The amine compound may be any of a primary amine compound, a secondary amine compound, a tertiary amine compound, and a diamine compound.

Specific examples of the amine compound include laurylamine, myristylamine, cetylamine, stearylamine, oleylamine, behenylamine, distearylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylstearylamine, dilaurylmonomethylamine, and trioctylamine. , Oleyl propylene diamine and the like.

(carboxylic acid)
Carboxylic acid is a compound containing at least one carboxyl group. The carboxylic acid may contain two or more carboxyl groups, or may contain a polymerizable functional group.

The weight average molecular weight of the carboxylic acid is preferably 150 or more and 50,000 or less from the viewpoint of being difficult to volatility, having excellent dispersibility, and being easy to work with. In the present specification, the "weight average molecular weight" is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting into polystyrene by a conventionally known gel permeation chromatography (GPC) method. The lower limit of the weight average molecular weight of the carboxylic acid is more preferably 300 or more, and the upper limit is more preferably 10,000 or less.

The carboxyl group equivalent (weight average molecular weight / number of carboxyl groups) of the carboxylic acid is preferably 150 or more and 50,000 or less from the viewpoint of facilitating the presence of the carboxylic acid around the quantum dots. The lower limit of the carboxyl group equivalent of the carboxylic acid is more preferably 300 or more, and the upper limit is more preferably 10,000 or less.

Specific examples of the above carboxylic acid include ω-carboxy-polycaprolactone mono (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, 2-acryloyloxyethyl succinic acid, a reaction product of pentaerythritol and acrylic acid, and succinate anhydride. Acid reactants include 3-butenoic acid, 10-undecenoic acid, n-octanoic acid, stearic acid, adipic acid, dodecanoic acid, 4,4'-dicarboxydiphenyl ether, octadecanoic acid and the like. Among these, ω-carboxy-polycaprolactone mono (meth) acrylate and 2-acryloyloxy from the viewpoint of fixing the carboxylic acid in the resin constituting the resin particles 2 and facilitating the presence of the carboxylic acid around the quantum dots. Ethyl succinic acid is preferred.

When the light-transmitting particles 19 are barrier particles, examples of the barrier particles include inorganic oxide particles. Examples of the inorganic oxide constituting the inorganic oxide particles include silicon oxide (SiO _x ) such as silica, aluminum oxide (Al _{n Om} ) such as alumina, titanium oxide (TiO ₂ ), yttrium oxide, and boron oxide (. B ₂ O ₃ ), calcium oxide (CaO), silicon oxide nitride (SiO _x N _{yC z} ), etc. Among these, silica or alumina such as glass from the viewpoint of low permeability of oxygen and water vapor. Is preferable. These materials may be used alone or in combination of two or more. It is also possible to use inorganic oxides other than oxide semiconductors.

<Coat layer>
When the light wavelength conversion particles include a coat layer that covers the surface of the light-transmitting particles, the function of the coat layer is not particularly limited. For example, the coat layer has a function of maintaining the shape of the light-transmitting particles and light transmission. A function to prevent the components in the sex particles from being eluted to the outside of the particles, a function to prevent the components in the dispersion liquid or the composition into the light-transmitting particles from permeating, a function to impart a barrier property to oxygen and water vapor, and a function to be incident on the light-transmitting particles. It has at least one of an antireflection function for excitation light and a light transmissive particle dispersibility imparting function when used as a dispersion liquid or composition.

The film thickness of the coat layer depends on the function exhibited by the coat layer, but is preferably 10 nm or more and 5000 nm or less, preferably 20 nm, from the viewpoint of ease of production and an appropriate size of the light-transmitting particles. More preferably 1000 nm or less. In particular, when the coat layer exerts a barrier property-imparting function, the film thickness of the coat layer is more preferably 50 nm or more and 1000 nm or less from the viewpoint of preventing cracks in the coat layer while maintaining the barrier property. The thickness of the coat layer is determined by photographing the cross section of the light wavelength conversion particle using a scanning electron microscope (SEM), measuring the thickness of the coat layer at 20 points in the image of the cross section, and measuring the thickness of the coat layer at 20 points. Let it be the average value of.

Although it depends on the function of the coat layer, when the coat layer has a function of retaining the shape of the resin particles, the coat layer can be formed by using, for example, a composition for a coat layer containing a polymerizable compound. .. The polymerizable compound (curable compound) contained in the composition for the coat layer is a polymerizable compound, and is, for example, an ionizing radiation polymerizable compound (ionizing radiation curable compound) or a thermosetting compound (thermosetting compound). Can be mentioned. Examples of the ionizing radiation polymerizable compound include the (meth) acrylate-based compound described in the above section of the binder resin, and examples of the thermopolymerizable compound include an epoxy compound and the like.

<Manufacturing method of light wavelength conversion particles>
When the light-transmitting particles 19 are resin particles, the light wavelength conversion particles 17 can also be produced by the following method. First, at least a composition for light wavelength conversion particles containing quantum dots, a polymerizable compound such as an epoxy compound or a (meth) acrylate compound, and the specific compound is dispersed in a poor solvent such as water. When the composition for light wavelength conversion particles contains an epoxy compound, the composition for light wavelength conversion particles may further contain a curing agent. When the composition for light wavelength conversion particles contains a (meth) acrylate-based compound, the composition for light wavelength conversion particles may further contain a radical polymerization initiator. Then, in a state where the composition for light wavelength conversion particles is dispersed in a granular state, the polymerizable compound in the composition for light wavelength conversion particles is polymerized by, for example, suspension polymerization or emulsion polymerization to obtain the light wavelength conversion particles. obtain. The “poor solvent” means a solvent in which the composition for light wavelength conversion particles is hardly dissolved, and examples thereof include polar solvents such as water. The composition for light wavelength conversion particles preferably contains a polymerization initiator.

When the light-transmitting particles 19 are resin particles, the light wavelength conversion particles 17 can also be produced by, for example, the following method. First, ionizing radiation or heat is applied to the composition for light wavelength conversion particles and cured to obtain a cured product of the composition for light wavelength conversion particles. Then, this cured product is pulverized by, for example, a bead mill. Thereby, light wavelength conversion particles can be obtained.

The content of the quantum dots in the composition for light wavelength conversion particles is preferably 0.01% by mass or more and 2% by mass or less, and more preferably 0.03% by mass or more and 1% by mass or less. If the quantum dot content is less than 0.01% by mass, sufficient emission intensity may not be obtained, and if the quantum dot content exceeds 2% by mass, sufficient excitation light is transmitted. There is a risk that strength will not be obtained.

The content of the polymerizable compound in the composition for light wavelength conversion particles is preferably 5% by mass or more and 80% by mass or less. If the content of the polymerizable compound is less than 5% by mass, the composition for light wavelength conversion particles is difficult to cure, and if the content of the polymerizable compound exceeds 80% by mass, the cured product becomes brittle and can be processed. It becomes difficult, and the content of a specific compound is reduced, so that sufficient durability may not be obtained.

The curing agent is used for reacting with an epoxy compound to cure the composition for light wavelength conversion particles or for the purpose of accelerating the curing reaction. As used herein, the term "curing agent" is a concept that includes not only a curing agent but also a curing accelerator. When a thiol compound is used as the specific compound, the thiol compound functions as a curing agent, so that it is not necessary to add a curing agent separately. The curing agent is not particularly limited, and is selected from the group consisting of, for example, an amine-based curing agent, a phenol-based curing agent, an acid anhydride-based curing agent, an imidazole-based curing agent, an organic phosphine-based curing agent, and a cationic polymerization initiator. One or more curing agents that are used. Among these, amine-based curing agents are preferable because curing can proceed at a low reaction temperature.

The content of the curing agent in the composition for light wavelength conversion particles is preferably 0.1% by mass or more and 80% by mass or less. If the content of the curing agent is less than 0.1% by mass, the composition for light wavelength conversion particles is difficult to cure, and if the content of the curing agent exceeds 80% by mass, the unreacted curing agent is reliable. May have an adverse effect on. The lower limit of the content of the curing agent in the composition for light wavelength conversion particles is more preferably 1% by mass or more, and the upper limit is more preferably 60% by mass or less.

(Amine-based curing agent)
Examples of the amine-based curing agent include aliphatic primary amines, secondary amines, tertiary amines, aromatic primary amines, secondary amines, tertiary amines, cyclic amines, guanidines, urea derivatives and the like. Specifically, triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, m-xylylenediamine, dicyandiamide, 1,8-diazabicyclo (5,4,0) -7-undecene, 1,5-diazabicyclo (4,3,0). Examples thereof include trialkylamines such as −5-nonen, dimethylurea, guanylurea, triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris (dimethylaminomethyl) phenol and the like.

(Phenolic hardener)
Examples of the phenolic curing agent include bifunctional phenols such as hydroquinone, resorcinol, catechol, bisphenol A, tetrabromobisphenol A, bisphenol F, bisphenol AF, bisphenol AD, biphenol, dihydroxynaphthalene, binaphthol, and fluorene-type bisphenol; Resin, cresol novolak resin, triazine ring-containing phenol novolac resin, triazine ring-containing cresol novolak resin, bisphenol A novolak resin, tetrabromobisphenol A novolak resin, bisphenol AF novolak resin, bisphenol AD novolak resin, biphenol novolak resin, fluorene-type bisphenol novolac Resins, novolak resins such as dicyclopentadiene-phenol novolac resin, dicyclopentadiene-cresol novolak resin; resol resins such as phenol resol resin and cresol resol resin can be mentioned.

(Acid anhydride-based curing agent)
Examples of the acid anhydride-based curing agent include phthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and a condensate of maleic anhydride and an unsaturated compound.

(Imidazole-based curing agent)
Examples of the imidazole-based curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, and 2-undecylimidazole.

(Organic phosphine-based curing agent)
Examples of the organic phosphine-based curing agent include triphenylphosphine, tributylphosphine, tris (p-methylphenyl) phosphine, tris (p-methoxyphenyl) phosphine, tris (p-ethoxyphenyl) phosphine, triphenylphosphine and triphenylborate. Examples thereof include tetraphenylphosphine and tetraphenylborate.

(Cationic polymerization initiator)
Cationic polymerization initiators are compounds that generate acids by ionizing radiation or heat. The cationic polymerization initiator is not particularly limited, but has an acid generating portion, stable performance, high solubility in the above compound having a heterocyclic group, and storage stability of the composition for photowavelength-converted particles. From the viewpoint of high content, one or more compounds selected from the group consisting of sulfonium salts, iodonium salts, and diazonium salts are preferable. Examples of ionizing radiation in the present specification include visible light and ultraviolet rays, X-rays, electron beams, α-rays, β-rays, and γ-rays.

(Radical polymerization initiator)
A radical polymerization initiator is a component that is decomposed by light or heat to generate radicals to initiate or proceed with the polymerization (crosslinking) of a (meth) acrylate-based compound. Examples of the radical polymerization initiator include a photoradical polymerization initiator and a thermal radical polymerization initiator.

Examples of the photoradical polymerization initiator include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanosen compounds, oxime ester compounds, benzoin ether compounds, thioxanthone and the like.

Examples of the thermal radical polymerization initiator include peroxides and azo compounds. Among these, a polymer azo initiator composed of a polymer azo compound is preferable. Examples of the polymer azo initiator include those having a structure in which a plurality of units such as polyalkylene oxide and polydimethylsiloxane are bonded via an azo group.

When the light-transmitting particles 19 are barrier particles, the light wavelength conversion particles 17 can be produced, for example, by using the sol-gel method (see Patent No. 5682069). Specifically, first, quantum dots are prepared, and an appropriate amount of a metal alkoxide (1) such as tetraethoxysilane is added to the quantum dots and hydrolyzed appropriately to make the surface of the quantum dots metal alkoxide. Replace with the hydrolyzate of (1). Such a liquid is referred to as an organic solvent A. On the other hand, an aqueous solution B is obtained by dispersing a metal alkoxide (2) such as 3-mercaptopropyltrimethoxysilane in the aqueous solution and partially hydrolyzing it. Here, the metal alkoxide (2) is selected to have a slower hydrolysis rate than the metal alkoxide (1). Then, by mixing the organic solution A and the aqueous solution B, a layer of the metal alkoxide (2) is further formed on the surface of the quantum dots covered with the metal alkoxide (1). Quantum dots that come into contact with water become hydrophilic because the metal alkoxide on the surface is hydrolyzed, and move to the aqueous phase. At this time, the quantum dots form an aggregate. Since the metal alkoxide (2) near the surface is hydrolyzed slower than the metal alkoxide (1), the alkoxide on the surface of the quantum dots is dehydrated and condensed at once when it moves to the aqueous phase, forming a large mass. prevent. An inorganic oxide layer such as a silica glass layer is further deposited on the aggregate in the aqueous phase. This can be done by hydrolyzing a small amount of metal alkoxide (3) in the alkaline region with a large amount of water and alcohol and depositing it on an aggregate of core quantum dots by the usual Stöber process. Thereby, light wavelength conversion particles can be obtained.

<Light scattering particles>
The light scattering particles 20 are particles having an action of changing the traveling direction of light by scattering the light that has entered the light wavelength conversion layer 11.

The average particle size of the light-scattering particles 20 is preferably 20 times or more and 2000 times or less, and more preferably 50 times or more and 1000 times or less of the average particle size of the quantum dots 18. If the average particle size of the light scattering particles is less than 20 times the average particle size of the quantum dots, sufficient light scattering performance may not be obtained in the light wavelength conversion layer or the light wavelength conversion unit, and the light scattering particles may not have sufficient light scattering performance. If the average particle size of is more than 2000 times the average particle size of quantum dots, the number of light-scattering particles will decrease even if the amount of addition is the same, so the number of scattering points will decrease and a sufficient light-scattering effect will be obtained. It may not be possible. The average particle size of the light-scattering particles 20 can be measured by the same method as the average particle size of the quantum dots 18 described above.

Further, the average particle size of the light scattering particles 20 is preferably 1/300 or more and 1/20 or less, and more preferably 1/200 or more and 1/30 or less of the average film thickness of the light wavelength conversion layer 11. preferable. If the average particle size of the light scattering particles is less than 1/300 of the average thickness of the light wavelength conversion layer, sufficient light scattering performance may not be obtained in the light wavelength conversion layer, and the average of the light scattering particles. If the particle size exceeds 1/20 of the average film thickness of the light wavelength conversion layer, the ratio of light scattering particles to the light wavelength conversion member decreases even if the amount added is the same, so that the number of scattering points is sufficiently reduced. No light scattering effect can be obtained.

Specifically, the average particle size of the light-scattering particles 20 is, for example, preferably 0.1 μm or more and 10 μm or less, and more preferably 0.3 μm or more and 5 μm or less. If the average particle size of the light scattering particles is less than 0.1 μm, the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, and the light scattering particles must have sufficient light scattering properties. It is necessary to increase the amount of addition. On the other hand, when the average particle size of the light-scattering particles exceeds 10 μm, the number of light-scattering particles decreases even if the addition amount (mass%) is the same, so that the number of scattering points decreases and a sufficient light-scattering effect is obtained. I can't get it.

The shape of the light-scattering particles 20 is not particularly limited, and for example, spherical (true spherical, substantially true spherical, elliptical spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate, flaky, indefinite. The shape and the like can be mentioned. When the shape of the light-scattering particles is not spherical, the particle size of the light-scattering particles can be a true spherical value having the same volume.

The light scattering particles 20 are preferably surface-treated with a silane coupling agent from the viewpoint of firmly fixing the light scattering particles 20 in the binder resin 16. By surface-treating with a silane coupling agent, it can be chemically bonded to the binder resin 16.

The silane coupling agent is composed of a vinyl group, an epoxy group, a styryl group, a methacryl group, an acrylic group, an amino group, a ureido group, a thiol group, a sulfide group and an isocyanate group, although it depends on the type of binder resin precursor used. It is possible to use one having one or more reactive functional groups selected from the group. When a (meth) acrylate compound is used as the binder resin precursor, the coupling agent is at least one reactive functional selected from the group consisting of a thiol group, a (meth) acryloyl group, a vinyl group and a styryl group. It is preferable to have a group.

The light-scattering particles may be organic particles such as acrylic resin particles, styrene resin particles, melamine resin particles, and urethane resin particles, but the rate of change in brightness before and after the heat resistance test can be reduced, and light can be used. Inorganic particles are preferable because the incident light on the wavelength conversion sheet can be suitably scattered and the light wavelength conversion efficiency with respect to the incident light can be preferably improved.

Inorganic particles include aluminum-containing compounds such as _{Al 2} O _{3 , zirconium-containing compounds such as ZrO 2} , tin-containing compounds such as antimony-doped tin oxide (ATO) and indium tin oxide (ITO), and magnesium such as _{MgO and MgF 2.} At least one compound selected from the group consisting of compounds, titanium-containing compounds such as _{TiO 2} and BaTiO ₃ , antimony-containing compounds such as _{Sb 2} O _{5 , silicon-containing compounds such as SiO 2, and zinc-containing compounds such as ZnO.} Particles can be mentioned. Since these inorganic particles can increase the difference in refractive index from the binder resin 16, they are also preferable from the viewpoint of obtaining a large Mie scattering intensity. The light scattering particles 20 may be made of two or more kinds of materials because the light wavelength conversion efficiency with respect to the incident light can be more preferably improved by the light wavelength conversion sheet 10.

The content of the light scattering particles 20 in the light wavelength conversion layer 11 is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. If the content of the light scattering particles is less than 1% by mass, the light scattering effect may not be sufficiently obtained, and if the content of the light scattering particles exceeds 50% by mass, Mie scattering occurs. Since it becomes difficult, there is a possibility that the light scattering effect cannot be sufficiently obtained, and further, the processability may be deteriorated because there are too many light scattering particles.

The absolute value of the difference in refractive index between the light-scattering particles 20 and the binder resin 16 is preferably 0.05 or more, and more preferably 0.10 or more, from the viewpoint of obtaining sufficient light scattering. The refractive index of the light-scattering particles 17 and the refractive index of the binder resin 16 may be larger. Here, as a method for measuring the refractive index of the light scattering particles before being contained in the light wavelength conversion layer, for example, the Becke method, the minimum deviation method, the deviation analysis, the mode line method, the ellipsometry method and the like are used. can do. As a method for measuring the refractive index of light-scattering particles, for example, the Becke method can be used for a piece of light-scattering particles or a piece of binder resin extracted from the light wavelength conversion layer in some form. .. In addition, the difference in refractive index between the binder resin and the light-scattering particles is measured using a phase-shift laser interference microscope (such as a phase-shift laser interference microscope manufactured by FK Optical Laboratory or a two-beam interference microscope manufactured by Mizojiri Optical Co., Ltd.). can do.

<< Light-transmitting substrate >>
The thicknesses of the light-transmitting substrates 12 and 13 are not particularly limited, but are preferably 10 μm or more and 300 μm or less. If the thickness of the light-transmitting substrates 12 and 13 is less than 10 μm, there is a risk of wrinkles and breaks during assembly and handling of the optical wavelength conversion sheet, and if it exceeds 300 μm, the weight of the display and the thin film may be reduced. It may not be suitable for conversion. The more preferable lower limit of the thickness of the light-transmitting substrates 12 and 13 is 50 μm or more, and the more preferable upper limit is 200 μm or less.

For the thickness of the light-transmitting base materials 12 and 13, a cross section of the light-transmitting base materials 12 and 13 is photographed using a scanning electron microscope (SEM), and the light-transmitting base materials 12 and 13 are imaged in the cross-sectional image. Measure the thickness at 20 points and use it as the average value of the film thickness at the 20 points.

Examples of the constituent raw materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulphon, and polysulphon. , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, or thermoplastic resins such as polyurethane. Preferred examples of the constituent materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate).

The light-transmitting base materials 12 and 13 may be composed of a single base material, or may be a laminated base material composed of a plurality of base materials. Such a laminated base material may be composed of a plurality of layers composed of layers of the same type of constituent raw materials, or may be composed of a plurality of layers composed of layers of different types of constituent raw materials, depending on the intended use. good.

<< Light diffusion layer >>
The light diffusion layers 14 and 15 have an uneven shape on the surface, and the uneven shape can diffuse the light incident on the light wavelength conversion sheet 10 and the light emitted from the light wavelength conversion sheet 10. By providing the light diffusion layers 14 and 15, the light wavelength conversion efficiency of the light wavelength conversion sheet 10 can be further improved. The light diffusing layers 14 and 15 contain light scattering particles and a binder resin.

<Light scattering particles>
The light-scattering particles in the light-diffusing layers 14 and 15 are mainly for forming an uneven shape on the surface of the light-diffusing layers 14 and 15 and exhibiting a light-scattering function.

The average particle size of the light-scattering particles in the light diffusion layers 14 and 15 is preferably 10 times or more and 20,000 times or less, and more preferably 10 to 5000 times the average particle size of the quantum dots 18 described above. preferable. If the average particle size of the light-scattering particles is less than 10 times the average particle size of the quantum dots, sufficient light-diffusivity may not be obtained in the light-diffusing layer, and the average particle size of the light-scattering particles may not be sufficient. If it exceeds 20,000 times the average particle size of the quantum dots, the light diffusion performance of the light diffusion layer becomes excellent, but the light transmission rate of the light diffusion layer tends to be significantly reduced. The average particle size of the light-scattering particles can be measured by the same method as the average particle size of the quantum dots 18 described above.

Specifically, the average particle size of the light-scattering particles in the light diffusing layers 14 and 15 is, for example, preferably 1 μm or more and 30 μm or less, and more preferably 1 μm or more and 20 μm or less. If the average particle size of the light scattering particles is less than 1 μm, the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, and the amount of the light scattering particles added in order to obtain sufficient light diffusivity. Need to be increased. On the other hand, when the average particle size of the light-scattering particles exceeds 30 μm, the light diffusing performance becomes excellent, but the light transmittance of the light diffusing layer tends to be significantly reduced.

The absolute value of the difference in refractive index between the light-scattering particles in the light diffusing layers 14 and 15 and the binder resin is preferably 0.02 or more and 0.15 or less. If it is less than 0.02, the light diffusivity due to the refractive index of the light scattering particles cannot be obtained optically, and the improvement of the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient. If it exceeds 15, the transmittance of the light diffusion layer may decrease. The more preferable lower limit of the difference in refractive index between the light scattering particles and the binder resin is 0.03 or more, and the more preferable upper limit is 0.12 or less. Either the refractive index of the light-scattering particles or the refractive index of the binder resin may be larger. The refractive indexes of the light-scattering particles and the binder resin can be measured by the same method as the refractive indexes of the light-scattering particles 17 and the binder resin.

Since the shapes of the light-scattering particles in the light-diffusing layers 14 and 15 are the same as the shapes of the light-scattering particles 17 in the light wavelength conversion layer 11, the description thereof will be omitted here. The light-scattering particles in the light diffusion layers 14 and 15 are preferably chemically bonded to the binder resin from the viewpoint of firmly fixing the light-scattering particles in the binder resin. This chemical bond can be realized by using light scattering particles surface-modified with a silane coupling agent. Since the silane coupling agent is the same as the silane coupling agent described in the section of light scattering particles in the light wavelength conversion layer, the description thereof will be omitted here.

The light scattering particles may be particles made of an organic material or particles made of an inorganic material. The organic material constituting the light-scattering particles is not particularly limited, and for example, polyester, polystyrene, melamine resin, (meth) acrylic resin, acrylic-styrene copolymer resin, silicone resin, benzoguanamine resin, benzoguanamine / formaldehyde condensation resin. , Polycarbonate, polyethylene, polyolefin and the like. Of these, crosslinked acrylic resin is preferably used. The inorganic material constituting the light diffusing particles is not particularly limited, and examples thereof include inorganic oxides such as silica, alumina, titania, tin oxide, antimony-doped tin oxide (ATO), and zinc oxide fine particles. Of these, silica and / or alumina are preferably used.

<Binder resin>
As the binder resin of the light diffusion layers 14 and 15, a cured product of a polymerizable compound can be used. As the polymerizable compound, the same polymerizable compound as that described in the column of the coat layer can be used, and thus the description thereof will be omitted here.

<< Other optical wavelength conversion sheets >>
As shown in FIG. 3, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 30 having only the optical wavelength conversion layer 11 (single layer structure). Further, as shown in FIG. 4, the light wavelength conversion sheet may be a light wavelength conversion sheet 40 including a light wavelength conversion layer 11 and a light transmissive base material 41 that supports the light wavelength conversion layer 11. .. By providing the light transmissive base material 41, the intensity of the light wavelength conversion sheet can be increased as compared with the light wavelength conversion sheet 30.

<Light transmissive base material>
As the light-transmitting base material 41 of the light wavelength conversion sheet 40, the same materials as those of the light-transmitting base materials 12 and 13 can be used, and thus the description thereof will be omitted here.

<< Other optical wavelength conversion sheets >>
As shown in FIGS. 5 and 6, the optical wavelength conversion sheet is arranged on at least one surface side of the optical wavelength conversion layer 11 and the optical wavelength conversion layer 11, and is integrated with the optical wavelength conversion layer 11. The optical wavelength conversion sheet 50 including the optical member 51 may be used.

<Optical member>
As used herein, the term "optical member" refers to optical properties (for example, polarization, photorefractiveness, light scattering, light reflectivity, light transmission, light absorption, photodiffraction, diversion, etc.). It means a member having, and is not particularly limited as long as it is a sheet (film) -shaped or plate-shaped member having optical characteristics. Examples of the optical member include an optical plate such as a lens sheet, a light guide plate and a light diffusing plate, a reflective polarizing separation sheet, a polarizing plate and the like. When the optical member sheets are provided on both sides of the optical wavelength conversion sheet, the optical members may be optical members having different optical characteristics. In this embodiment, an example in which the optical member is a lens sheet will be described.

As shown in FIGS. 5 and 6, the optical member 51 includes a light-transmitting base material 52 and a lens layer 53 provided on one surface of the light-transmitting base material 52. As shown in FIGS. 5 and 6, the lens layer 53 includes a sheet-shaped main body 54 and a plurality of unit lenses 55 arranged side by side on the light emitting side of the main body 54. The light-transmitting base material 52, the lens layer 53, the main body portion 54, and the unit lens 55 have the same configurations as the light-transmitting base material 111, the lens layer 112, the main body portion 113, and the unit lens 114, which will be described later. Therefore, the description thereof will be omitted here.

In the optical wavelength conversion sheet 50, the optical wavelength conversion layer 11 and the optical member 51 are integrated by directly applying and curing the optical wavelength conversion particle-containing composition on one surface of the optical member 51. The optical wavelength conversion layer 11 and the optical member 51 may be bonded to each other via an adhesive layer.

<< Other optical wavelength conversion sheets >>
As shown in FIG. 7, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 60 including an optical wavelength conversion layer 11 and overcoat layers 61 and 62 covering both surfaces of the optical wavelength conversion layer 11. In the present embodiment, the overcoat layers 61 and 62 are formed on both sides of the light wavelength conversion layer 11, but if the overcoat layer is formed on at least one surface of the light wavelength conversion layer, the light wavelength conversion is performed. It does not have to be formed on both sides of the layer 11. When the overcoat layer is provided on only one surface of the light wavelength conversion layer, a light transmissive base material may be provided on the other surface of the light wavelength conversion layer.

<Overcoat layer>
The overcoat layers 61 and 62 are layers made of a resin that covers the surface of the light wavelength conversion layer 11 and is formed by coating. Other layers such as a light diffusion layer may be formed on the overcoat layers 61 and 62.

The overcoat layers 61 and 62 are provided to prevent the light wavelength conversion layer 11 from being directly exposed to the atmosphere. By providing such overcoat layers 61 and 62 on at least one surface of the light wavelength conversion layer 11, the quantum dots 4 can be more protected from moisture and oxygen, and the light transmissive substrate can be converted to light wavelength. The thickness of the light wavelength conversion sheet can be made thinner than that provided on at least one surface of the layer 11.

The overcoat layers 61 and 62 may have some function other than the function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. Specifically, the overcoat layers 61 and 62 may be, for example, a layer having at least one of functions such as antiblocking property, light diffusing property, antistatic property, and antireflection property. When the overcoat layers 61 and 62 are layers having a function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and some other function, the overcoat layers 61 and 62 are for having some function. The material may be added.

The film thickness of the overcoat layers 61 and 62 is 0.1 μm or more and 100 μm or less from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and thinning the light wavelength conversion sheet. Is preferable. The film thicknesses of the overcoat layers 61 and 62 can be measured by the same method as the film thickness of the light wavelength conversion layer 11. The lower limit of the film thickness of the overcoat layers 61 and 62 is more preferably 1 μm or more, and the upper limit is more preferably 50 μm or less.

The overcoat layers 61 and 62 preferably have a hardness of at least one of a vertical force of 10 μN or more and a horizontal force of −5 μN or less in the scratch test. When the overcoat layers 51 and 52 have such hardness, the overcoat layers 61 and 62 become a dense film, so that the ability to prevent the light wavelength conversion layer 11 from exposure to the atmosphere is high. The vertical force and horizontal force in the scratch test are indented (Cube) from the cross section of the overcoat layer to the inside of the overcoat layer using a nanoindentation device (product name "TI950 TriboIndenter", manufactured by HYSITRON). Corner: Ti037_110410 (12)) is pushed in by 50 nm, the depth is kept constant, and the average vertical force (load) and horizontal force measured when this indenter is moved horizontally at a moving speed of 4 μm / min for 30 seconds. The values were obtained respectively, and the average value of the five average values of the vertical force (5 times average value) and the average value of the five average values of the horizontal force (5 times average value) obtained by repeating this scratch test 5 times. And. The larger the value of the normal force and the smaller the value of the horizontal force, the higher the hardness of the overcoat layers 61 and 62. From the viewpoint of enhancing the ability to prevent the light wavelength conversion layer 11 from exposure to the atmosphere, the normal force of the overcoat layers 61 and 62 in the scratch test is more preferably 15 μN or more, and the horizontal force is more preferably -8 μN or less. preferable.

The overcoat layers 61 and 62 are not particularly limited as long as they have the above hardness, but for example, (meth) acrylate compounds, epoxy compounds, combinations of isocyanates and polyols, metal alkoxides, silicon-containing resins, water-soluble polymers, etc. Alternatively, it can be formed by using a composition for an overcoat layer containing a mixture thereof. Among these, the overcoat layers 61 and 62 are zinc acrylate, a hydrolysis product of alkoxysilane, polyvinyl alcohol, polysilazane, or these, from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. It is preferably formed using a composition for an overcoat layer containing a mixture.

In the optical wavelength conversion sheet 30, 40, 50 and 60, the entire sheet, 40 ° C., water vapor transmission rate of 90% relative humidity may be a 0.1g ^/ (m 2 · 24h) or more. In the optical wavelength conversion sheet 30, 40, 50 and 60, the entire sheet, 23 ° C., even oxygen permeability at a relative humidity of 90% has become a ^{0.1cm 3 / (m 2 · 24h} · atm) or higher good. 40 ° C. in the optical wavelength conversion sheet 30, 40, 50 and 60, the water vapor transmission rate of 90% relative humidity may be made with 1g ^/ (m 2 · 24h) or more, the optical wavelength conversion sheet 30, 40, 23 ° C. in 50 and 60, the oxygen permeability at 90% relative humidity may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

<< Other optical wavelength conversion sheets >>
The light wavelength conversion sheet may be a light wavelength conversion sheet 70 as shown in FIG. In this case, the water vapor transmittance and the oxygen transmittance of the light wavelength conversion sheet 70 do not have to be within the above-mentioned ranges.

The light wavelength conversion sheet 70 shown in FIG. 8 is the light wavelength conversion layer 11, the barrier films 71 and 72 provided on both sides of the light wavelength conversion layer 11, and the light wavelength conversion layer 11 side of the barrier films 71 and 72. It is provided with light diffusion layers 13 and 14 provided on the side opposite to the surface. In the light wavelength conversion sheet 70, the surfaces of the light diffusion layers 13 and 14 constitute the surfaces 70A and 70B of the light wavelength conversion sheet 70.

<Barrier film>
The barrier films 71 and 72 are members for suppressing the permeation of water and oxygen to protect the quantum dots 18 from water and oxygen. Here, the "barrier film" herein is a member Tantai, 40 ° C., water vapor transmission rate of 90% relative humidity becomes 0.1g ^/ (m 2 · 24h) below, and 23 ° C., relative humidity oxygen transmission rate at 90% is intended to mean a member made of a ^{0.1cm 3 / (m 2 · 24h} · atm) of less than. The barrier film includes not only a film having a single layer structure but also a film having a multilayer structure. By installing the barrier films 71 and 72 with the light wavelength conversion layer 11 sandwiched between them, the heat resistance and moisture resistance of the quantum dots 18 can be further improved. The barrier films 71 and 72 shown in FIG. 8 are provided on the light transmissive base materials 12 and 13 and the light wavelength conversion layer 11 side of the light transmissive base materials 12 and 13, and suppress the permeation of water and oxygen. It includes barrier layers 73 and 74 having a function.

Water vapor permeability of the barrier film 71,72 (WVTR: Water Vapor Transmission Rate ) is, 40 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 g} / (m 2 · 24h) that less is Is more preferable. The water vapor transmission rate can be measured using a water vapor transmission rate measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON).

Oxygen permeability of the barrier film 71,72 (OTR: Oxygen Transmission Rate) is, 23 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 cm} 3 / (m 2 · 24h · atm) or less It is more preferable to have. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON).

(Barrier layer)
The barrier layers 73 and 74 are composed of a thin-film deposition layer having a function of suppressing the permeation of water and oxygen. The thin-film deposition layer is a layer formed by a vapor deposition method such as a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method or a chemical vapor deposition (CVD) method. The thin-film deposition layer has the advantage that the barrier property can be enhanced.

The material for forming the thin-film vapor deposition layer is not particularly limited as long as it can be vapor-deposited by a thin-film deposition method and has a barrier property, and examples thereof include inorganic oxides such as silicon oxide and aluminum oxide, and metals.

The film thickness of the vapor-deposited layer is not particularly limited, but is preferably 0.01 μm or more and 1 μm or less. If the film thickness of the thin-film vapor deposition layer is less than 0.01 μm, the barrier performance of the thin-film deposition layer may be insufficient, and if it exceeds 1 μm, the barrier performance may be easily deteriorated due to cracks in the thin-film deposition layer. be. The more preferable lower limit of the thickness of the vapor-deposited layer is 0.03 μm or more, and the more preferable upper limit is 0.5 μm or less.

The film thickness of the thin-film deposition layer is determined by photographing the cross section of the optical wavelength conversion sheet 60 using a scanning electron microscope (SEM), measuring the film thickness of the vapor-deposited film at 20 points in the image of the cross section, and measuring the film thickness at 20 points. The average thickness. Further, the thin-film deposition layer may be a single layer or a laminated layer of a plurality of layers. When a plurality of thin-film vapor deposition layers are laminated, each layer constituting the thin-film deposition layer may be directly laminated or laminated.

<<< Manufacturing method of optical wavelength conversion sheet >>>
The optical wavelength conversion sheet 10 can be produced, for example, as follows. First, although not shown, a light-diffusing layer composition containing light-scattering particles and a polymerizable compound is applied to one surface of the light-transmitting base material 12, dried, and then coated with the light-diffusing layer composition. Form a film. Similarly, a coating film of the composition for the light diffusion layer is formed on one surface of the light-transmitting base material 13.

Next, the coating film of the composition for the light diffusion layer is cured by light irradiation or the like. As a result, as shown in FIG. 9A, the light diffusing layer 14 is formed on one surface of the light transmitting base material 12, and the light transmitting base material 12 with the light diffusing layer 14 is formed. Further, although not shown, the light transmissive base material 13 with the light diffusing layer 15 is formed in the same manner.

After forming the light-transmitting base material 13 with the light-diffusing layer 15, as shown in FIG. 9B, the side of the light-transmitting base material 13 with the light-diffusing layer 15 opposite to the surface on the light-transmitting layer 15 side. A composition containing at least light wavelength conversion particles 17 and a light wavelength conversion particle-containing composition containing a binder resin precursor such as a (meth) acrylate compound, which becomes a binder resin 16 after curing, is applied to the surface of the surface, and dried. The coating film 21 of the light wavelength conversion particle-containing composition is formed. The light wavelength conversion particle-containing composition may further contain a polymerization initiator in addition to the light wavelength conversion particles 1 and the binder resin precursor. The light wavelength conversion particle-containing composition preferably further contains the light-scattering particles 20, and may also contain an additive or a solvent.

The content of the polymerization initiator in the light wavelength conversion particle-containing composition is preferably 0.3 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the binder resin precursor. If the content of the polymerization initiator is less than 0.3 parts by mass, the binder resin precursor is difficult to cure, and if it exceeds 5.0 parts by mass, the optical wavelength conversion sheet may turn yellow. be.

After forming the coating film 21 of the light wavelength conversion-containing composition, as shown in FIG. 10A, the surface of the light transmitting base material 12 with the light diffusing layer 14 opposite to the surface on the light diffusing layer 14 side is described above. The light transmissive base material 12 with the light diffusion layer 14 is arranged on the coating film 21 of the light wavelength conversion particle-containing composition so as to be in contact with the coating film 21 of the light wavelength conversion particle-containing composition. As a result, the coating film 21 of the light wavelength conversion particle-containing composition is sandwiched between the light-transmitting base materials 12 and 13.

Next, as shown in FIG. 10B, the coating film 21 of the light wavelength conversion particle-containing composition is irradiated with ionizing radiation or the coating film 21 is heated via the light transmissive substrate 12. The light wavelength conversion particle-containing composition mixture is cured to form the light wavelength conversion layer 11, and the light wavelength conversion layer 11, the light transmissive base material 12 with the light diffusing layer 14, and the light transmissive with the light diffusing layer 15 are transmitted. The sex substrate 13 is integrated. As a result, the optical wavelength conversion sheet 10 shown in FIG. 1 is obtained.

The optical wavelength conversion sheets 30, 40, and 60 can be produced, for example, as follows. First, the light wavelength conversion particle-containing composition is applied onto a base material (not shown) and dried to form a coating film of the light wavelength conversion particle-containing composition. Then, the light wavelength conversion layer 11 is formed by irradiating the coating film with ionizing radiation or applying heat to cure the binder resin precursor. Then, the base material is peeled off from the light wavelength conversion layer 11. As a result, the optical wavelength conversion sheet 30 shown in FIG. 3 is obtained. On the other hand, when the light transmissive base material 41 is used as the base material, the light wavelength conversion sheet 40 shown in FIG. 4 can be obtained by leaving the base material as it is without peeling it from the light wavelength conversion layer 11. can get. In the light wavelength conversion sheet 60 shown in FIG. 7, the composition for the overcoat layer is applied to at least one surface of the light wavelength conversion sheet 30 to form a coating film of the composition for the overcoat layer, and this coating film is formed. Can be formed by curing. The light wavelength conversion sheet 60 can also be formed by the following method. First, the composition for the overcoat layer is applied to one surface of the two substrates to form a coating film of the composition for the overcoat layer. After forming the coating film, the coating film of each overcoat layer composition is irradiated with ionizing radiation or heated to form an overcoat layer. After forming the overcoat layer, the light wavelength conversion particle-containing composition is applied onto the overcoat layer formed on one of the base materials to form a coating film of the light wavelength conversion particle-containing composition. Next, the other base material is placed on the coating film of the light wavelength conversion particle-containing composition so that the overcoat layer formed on the other base material is in contact with the coating film of the light wavelength conversion particle-containing composition. Next, in this state, the coating film of the composition containing light wavelength conversion particles is irradiated with ionizing radiation or heated to form a light wavelength conversion layer, and the light wavelength conversion layer and the overcoat layer are formed. Integrate. Finally, when both substrates are peeled off, the optical wavelength conversion sheet 60 shown in FIG. 7 is obtained.

The light wavelength conversion sheet 50 is coated with the light wavelength conversion particle-containing composition on one surface side of the optical member 51 and dried to form a coating film of the light wavelength conversion particle-containing composition. Then, the light wavelength conversion layer 11 is formed by applying heat to the coating film or irradiating it with ionizing radiation to cure the binder resin precursor. As a result, the optical wavelength conversion sheet 50 shown in FIG. 5 is obtained.

The light wavelength conversion sheet 70 is a barrier in which the light diffusion layers 14 and 15 are provided with the light transmitting base materials 12 and 13 and the barrier layers 73 and 74 formed on one surface of the light transmitting base materials 12 and 13. If it is formed on the films 71 and 72, it can be formed by the same process as the light wavelength conversion sheet 10.

The optical wavelength conversion sheets 10, 30, 40, 50, 60, and 70 can be used by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion sheet 10 is incorporated into a backlight device and an image display device will be described. 11 is a schematic configuration diagram of an image display device including a backlight device according to the present embodiment, FIG. 12 is a perspective view of the lens sheet shown in FIG. 11, and FIG. 13 is a perspective view of the lens sheet of FIG. It is a cross-sectional view along line II. 14, 15, and 17 are schematic configuration diagrams of other backlight devices according to the present embodiment, FIG. 16 is a schematic configuration diagram of the light source shown in FIG. 15, and FIG. 18 is a schematic configuration diagram of the light source shown in FIG. It is an enlarged view near the light source surface of an optical plate.

<<< Image display device >>>
The image display device 80 shown in FIG. 11 includes a backlight device 90 and a display panel 130 arranged on the light emitting side of the backlight device 90. The image display device 80 has a display surface 80A for displaying an image. In the image display device 80 shown in FIG. 11, the surface of the display panel 130 is the display surface 80A.

<< Display panel >>
The display panel 130 shown in FIG. 11 is a liquid crystal display panel, and is between the polarizing plate 131 arranged on the light entering side, the polarizing plate 132 arranged on the light emitting side, and the polarizing plate 131 and the polarizing plate 132. It includes an arranged liquid crystal cell 133.

<< Backlight device >>
The backlight device 90 shown in FIG. 11 is configured as an edge light type backlight device, and includes a light source 100, an optical plate 105 as a light guide plate arranged on the side of the light source 100, and a light emitting side of the optical plate 105. The optical wavelength conversion sheet 10 arranged in the light wavelength conversion sheet 10, the lens sheet 110 arranged on the light source side of the light wavelength conversion sheet 10, the lens sheet 115 arranged on the light source side of the lens sheet 110, and the light source side of the lens sheet 115. It includes a reflective polarizing separation sheet 120 arranged and a reflective sheet 125 arranged on the side opposite to the light emitting side of the optical plate 105. The backlight device 90 includes an optical plate 105, lens sheets 110 and 115, a reflective polarizing separation sheet 120, and a reflective sheet 125, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side of each member where light emitted in the direction of emission from the backlight device is emitted.

The backlight setting 90 has a light emitting surface 90A that emits light in a planar manner. In the backlight device 90 shown in FIG. 11, the light emitting surface of the reflective polarizing separation sheet 120 is the light emitting surface 90A of the backlight device 90.

The surface of the optical wavelength conversion sheet 10 on the optical plate 105 side is the surface 10A (light incoming surface), and the surface of the optical wavelength conversion sheet 10 on the lens sheet 110 side is the surface 10B (light emitting surface).

<Light source>
The light source 100 includes, for example, a fluorescent lamp such as a linear cold-cathode tube, or a light emitter such as a point-shaped light emitting diode (LED) or an incandescent light bulb. In the present embodiment, the light source 100 is provided by a large number of point-shaped light emitters, specifically, a large number of light emitting diodes (LEDs), which are linearly arranged on the light receiving surface 105C side of the optical plate 105, which will be described later. ,It is configured.

Since the light wavelength conversion sheet 10 is arranged in the backlight device 90, the light source 100 can use only a light emitting body that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light having high color purity can be used.

<Optical plate>
The optical plate 105 as a light guide plate has a quadrangular shape in a plan view. The optical plate 105 extends between the light emitting surface 105A formed by one main surface on the display panel 130 side, the back surface 105B composed of the other main surface facing the light emitting surface 105A, and the light emitting surface 105A and the back surface 105B. Has sides. The side surface of the side surface on the light source 100 side is an incoming light surface 105C that receives light from the light source 100. The light incident on the optical plate 105 from the light entry surface 105C is guided in the optical plate in the direction connecting the light entry surface 105C and the opposite surface facing the light entry surface 105C (light guide direction), and is guided through the optical plate to the light emission surface. Emitted from 105A.

<Lens sheet>
The lens sheets 110 and 115 have a function of changing the traveling direction of the incident light and emitting the incident light from the light emitting side. In the present embodiment, as shown in FIG. 13, a function (condensing function) of changing the traveling direction of light L3 having a large incident angle and emitting it from the light emitting side to intensively improve the brightness in the front direction. At the same time, it has a function (retroreflection function) of reflecting light L4 having a small incident angle and returning it to the light wavelength conversion sheet 10 side. The lens sheets 110 and 115 include a light-transmitting base material 111 and a lens layer 112 provided on one surface of the light-transmitting base material 111.

When the surfaces 10A and 10B of the optical wavelength conversion sheet 10 are uneven surfaces, the light emitting surface 105A of the optical plate 105 is optically in close contact with a part (for example, a convex portion) of the surface 10A, and is also a surface. It is preferable that the lens sheet 110 is separated from other parts (for example, concave parts) of 10A, and the light entering surface 110A of the lens sheet 110 is optically in close contact with a part (for example, convex parts) of the surface 10B and also has a surface. It is preferable that the 10B is separated from other parts (for example, recesses). In this case, the gap between the light emitting surface 105A and the other part of the surface 10A and the gap between the light entering surface 110A and the other part of the surface 10B are an air layer. By providing this air layer, the light wavelength conversion sheet 10, the optical plate 105, and the lens sheet 110 are fixed so that the light emitting surface 105A and the surface 10A and the light entering surface 110A and the surface 10B are in optical contact with each other. However, since it is possible to prevent the light wavelength conversion sheet 10 from sticking to the optical plate 105 and the lens sheet 110, the interface between the light wavelength conversion sheet 10 and the optical plate 105 and the light wavelength conversion sheet 10 and the lens sheet 110 It is possible to suppress the formation of wet-out at the interface between the light and the light.

(Light transmissive base material)
Since the light-transmitting base material 111 is the same as the light-transmitting base materials 12 and 13, the description thereof will be omitted here.

(Lens layer)
As shown in FIGS. 12 and 13, the lens layer 112 includes a sheet-shaped main body 113 and a plurality of unit lenses 114 arranged side by side on the light emitting side of the main body 113.

The main body 113 functions as a sheet-like member that supports the unit lens 114. As shown in FIGS. 12 and 13, unit lenses 114 are arranged on the light emitting side surface 113A of the main body 113 without any gap. Therefore, the light emitting surfaces 110B and 115B of the lens sheets 110 and 115 are formed by the lens surfaces. On the other hand, as shown in FIG. 13, the main body 113 has a smooth surface forming the light entering side surface of the lens layer 112 as the light entering side surface 113B facing the light emitting side surface 113A.

The unit lenses 114 are arranged side by side on the light emitting side surface 113A of the main body 113. As shown in FIG. 12, the unit lens 114 extends linearly in a direction intersecting the arrangement direction AD of the unit lens 114, particularly linearly in the present embodiment. Further, in the present embodiment, a large number of unit lenses 114 included in one lens sheet 110, 115 extend in parallel with each other. Further, the longitudinal LD of the unit lenses 114 of the lens sheets 110 and 115 is orthogonal to the arrangement direction AD of the unit lenses 114 of the lens sheets 110 and 115.

The unit lens 114 may have a triangular columnar shape, or may have a wavy shape or a bowl shape such as a hemispherical shape. Specifically, examples of the unit lens include a unit prism, a unit cylindrical lens, a unit microlens, and the like. Examples of the lens sheet having such a unit lens shape include a prism sheet, a lenticular lens sheet, and a microlens sheet.

From the viewpoint of improving the efficiency of light utilization, the unit lens 114 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably about 90 °. However, considering the damage to the tip of the unit lens when winding the optical wavelength conversion sheet, the tip of the unit lens 104 may be a curved surface.

The dimensions of the lens sheets 110 and 115 can be set as follows, for example. First, as a specific example of the unit lens 114, the arrangement pitch of the unit lens 114 (corresponding to the width of the unit lens 104 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, the arrangement of the unit lens 114 has been rapidly improved in definition, and it is preferable that the arrangement pitch of the unit lens 114 is 10 μm or more and 50 μm or less. Further, the protruding height of the unit lens 114 from the main body 113 along the normal direction ND of the lens sheets 110 and 115 to the sheet surface can be set to 5 μm or more and 100 μm or less. Further, the apex angle θ of the unit lens 114 can be set to 60 ° or more and 120 ° or less.

As can be understood from FIG. 11, the arrangement direction of the unit lens 114 of the lens sheet 110 and the arrangement direction of the unit lens 114 of the lens sheet 115 intersect, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 120 transmits only the first linearly polarized light component (for example, P-polarized light) among the light emitted from the lens sheet 115, and is a second straight line orthogonal to the first linearly polarized light component. It has a function of reflecting polarized light components (for example, S-polarized light) without absorbing them. The second linearly polarized light component reflected by the reflective polarization separation sheet 120 is reflected again and the polarized light is eliminated (a state in which both the first linearly polarized light component and the second linearly polarized light component are included). It is incident on the reflective polarizing separation sheet 120 again.

As the reflective polarizing separation sheet 120, "DBEF" (registered trademark) available from 3M can be used. In addition to "DBEF", a high-intensity polarizing sheet "WRPS" available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarizing separation sheet 90.

<Reflective sheet>
The reflective sheet 125 has a function of reflecting the light leaked from the back surface 105B of the optical plate 105 and causing it to enter the optical plate 105 again. The reflective sheet 125 is composed of a white scattered reflective sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain.

<< Other backlight devices >>
The backlight device incorporating the optical wavelength conversion sheet 10 may be a direct type backlight device as shown in FIG. The backlight device 140 shown in FIG. 14 includes a light source 100, an optical plate 141 that receives the light of the light source 100 and functions as a light diffusing plate, and an optical wavelength conversion sheet 10 arranged on the light emitting side of the optical plate 141. The lens sheet 110 arranged on the light emitting side of the optical wavelength conversion sheet 10, the lens sheet 115 arranged on the light emitting side of the lens sheet 110, and the reflective polarization separation sheet 120 arranged on the light emitting side of the lens sheet 115. I have. In the present embodiment, the light source 100 is arranged directly below the optical plate 141, not on the side of the optical plate 141. In FIG. 14, the members having the same reference numerals as those in FIG. 11 are the same as the members shown in FIG. 11, and thus the description thereof will be omitted. The backlight device 140 is not provided with the reflective sheet 125.

<Optical plate>
The optical plate 141 as a light diffusing plate has a quadrangular shape in a plan view. The optical plate 141 has an incoming light incident surface 141A formed by one main surface on the light source 100 side and an outgoing light emitting surface 141B formed by the other main surface on the optical wavelength conversion sheet 10 side. The light incident on the optical plate 141 from the light incoming surface 141A is diffused in the optical plate 141 and emitted from the light emitting surface 141B.

<< Other backlight devices >>
The backlight device 90 shown in FIG. 11 includes an optical wavelength conversion sheet 10, but the structure of the backlight device is not particularly limited as long as it includes an optical wavelength conversion member. For example, as shown in FIG. 15, the backlight device may be a backlight device 150 provided with a light source 160 instead of the light wavelength conversion sheet 10 and the light source 100. The light source 160 is a form of a light wavelength conversion member.

As shown in FIG. 16, the light source 160 has a substrate 161 and a reflection member 162 having an opening 162A arranged on the substrate 161 and a light emitting member arranged on the substrate 161 and in the opening 162A of the reflection member 162. A light source 163 such as a diode and an optical wavelength conversion unit 164 filled in the opening 162A of the reflection member 162 so as to cover the light source 163 are provided.

The light wavelength conversion unit 164 is different from the light wavelength conversion layer 11 in shape and arrangement, and the configuration and physical properties of the light wavelength conversion unit 164 are the same as those of the light wavelength conversion layer 11. The light wavelength conversion unit 164 includes the light wavelength conversion particles 17 and the binder resin 16, and the refractive index of the surface of the light wavelength conversion particles 17 is larger than the refractive index of the binder resin 16. As the binder resin 16 contained in the light wavelength conversion unit 164, an epoxy resin or a silicone resin is preferable. The light wavelength conversion unit 164 can be formed by filling the opening 162A of the reflection member 162 with a light wavelength conversion-containing composition containing the light wavelength conversion particles 17 and a binder resin precursor and thermally curing the composition. When the light source 160 having the light wavelength conversion unit 164 is used, the structure is not particularly limited as long as the light wavelength conversion unit 164 is arranged so as to cover the light emitting body 163.

<< Other backlight devices >>
The backlight device may be the backlight device 170 shown in FIG. Specifically, the backlight device 170 shown in FIG. 17 includes an optical plate 180 instead of the light wavelength conversion sheet 10. The optical plate 180 is a form of an optical wavelength conversion member.

The optical plate 180 is provided with an optical wavelength conversion layer 182 as an optical wavelength conversion unit on the light incoming surface 181A of the optical plate main body 181. The light wavelength conversion layer 182 is linearly arranged so that the longitudinal direction is along the arrangement direction of the light sources 100.

The optical plate main body 181 is the same as the optical plate 105, and the optical wavelength conversion layer 182 is different from the optical wavelength conversion layer 11 only in the arrangement location and shape, and the configuration and physical properties of the optical wavelength conversion layer 181 are optical wavelength conversion. Since it is the same as the layer 11, the description thereof will be omitted here.

Although it depends on the angle of light incident on the light wavelength conversion particles, if the refractive index of the surface of the light wavelength conversion particles is smaller than the refractive index of the binder resin, it advances through the binder resin and the surface of the light wavelength conversion particles. There is a risk that the light that reaches the light will be totally reflected on the surface of the light wavelength conversion particles. On the other hand, according to the present embodiment, the refractive index of the surface of the light wavelength conversion particles 17 is larger than the refractive index of the binder resin 16, so that the light wavelength conversion particles 17 are incident on the light wavelength conversion layer 11 and the binder resin 16 is incident on the light wavelength conversion layer 11. It is possible to prevent the light traveling through the light from being totally reflected on the surface of the light wavelength conversion particles 17. Therefore, since more light enters the light wavelength conversion particles 17, the amount of light whose wavelength is converted by the quantum dots 18 existing in the light wavelength conversion particles 17 increases. Thereby, the light wavelength conversion efficiency can be improved. Moreover, since the light wavelength conversion efficiency can be improved, the amount of quantum dots used can be reduced.

If the refractive index of the surface of the light wavelength conversion particles is larger than the refractive index of the binder resin, total reflection may occur when the light wavelength conversion particles are emitted from the binder resin. The refractive index is wavelength-dependent, and generally, the shorter the wavelength, the larger the refractive index. Therefore, the shorter the wavelength, the larger the difference in refractive index between the material constituting the surface of the light wavelength conversion particles and the binder resin. Therefore, the short wavelength light is more likely to be from the light wavelength conversion particles to the binder resin than the long wavelength light. It becomes easy to be totally reflected when it emits light. Therefore, when a quantum dot that converts blue light into green light or red light is used as the quantum dot, the blue light that has not been wavelength-converted is likely to be totally reflected when emitted from the light wavelength-converted particle to the binder resin. At the same time, the wavelength-converted green light and red light are less likely to be totally reflected when they are emitted from the light wavelength-converted particles to the binder resin. Therefore, green light and red light can be emitted from the light wavelength conversion particles, and the blue light totally reflected when the light wavelength conversion particles are emitted to the binder resin is wavelength-converted in the light wavelength conversion particles. be able to. Thereby, the light wavelength conversion efficiency can be further improved.

It is considered that the reason why quantum dots are easily deteriorated by heat resistance test and moisture heat resistance test is as follows. First, as described above, a ligand composed of a sulfur-based compound, a phosphorus-based compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily desorbed by light or heat. When the ligand is desorbed from the quantum dots, water and oxygen are likely to adhere to the quantum dots, so that the quantum dots are oxidized and deteriorated. As a result, it is considered that the quantum dots are deteriorated by the heat resistance test and the moisture heat resistance test. On the other hand, when the light-transmitting particles 19 are resin particles, the resin particles contain at least one of one or more elements and a carboxylic acid selected from the group consisting of sulfur, phosphorus, and nitrogen. Therefore, at least one of a sulfur component, a phosphorus component, a nitrogen component and a carboxylic acid can be present in the vicinity of the quantum dots 18, whereby excellent heat resistance and moist heat resistance can be obtained. This is such that at least one of the sulfur component, phosphorus component, nitrogen component and carboxylic acid present in the resin particles assists the role of the ligand even when the ligand is desorbed from the quantum dots (for example). It is considered that this is because the deterioration of the quantum dot is suppressed because it exerts at least one of the function of binding to the quantum dot instead of the ligand and the function of substituting the ligand and the function of capturing oxygen). Further, when the light-transmitting particles 19 are barrier particles, it is difficult for water and oxygen to permeate through the barrier particles, so that it is difficult for water and oxygen to adhere to the quantum dots 18, which results in excellent heat resistance and moist heat resistance. Can be obtained.

According to the present embodiment, the deterioration of the quantum dots 18 can be suppressed by the light-transmitting particles 19 of the light wavelength conversion particles 17, so that the barrier film is omitted as in the light wavelength conversion sheets 10, 30, 40, 50, 60. can. As a result, the process of the light wavelength conversion sheet can be simplified, so that the quality can be easily improved and the light wavelength conversion sheet can be made thinner.

In an optical wavelength conversion sheet provided with a barrier film, when a heat resistance test or a moist heat resistance test is performed, punctate defects such as pinholes and cracks are likely to occur in the barrier film. When a defect portion is generated in the barrier film, moisture or oxygen may enter from the defect portion, and some quantum dots may be deteriorated to generate a point-like reduced brightness portion (luminance defect) in the optical wavelength conversion sheet. .. This punctate luminance defect is more easily visible than in the case where the quantum dots are deteriorated as a whole and the luminance is uniformly lowered. On the other hand, according to the present embodiment, the light transmissive particles 19 of the light wavelength conversion particles 17 can suppress the deterioration of the quantum dots 18, so that even if the barrier films 71 and 72 have defects, this defect occurs. Even when water or oxygen enters from the portion, it is possible to suppress the point-like brightness defect.

According to the present embodiment, the deterioration of the quantum dots 18 can be suppressed by the light-transmitting particles 19 of the light wavelength conversion particles 17, and therefore, in the light wavelength conversion sheets 10, 30, 40, 50, 60, 70, the peripheral portion 10C, Deterioration of the quantum dots 18 existing at 30A, 40A, 50A, 60A, and 70C can also be suppressed.

In the optical wavelength conversion sheet 50, since the optical wavelength conversion layer 11 and the optical member 51 are integrated, the optical wavelength conversion sheet and the optical member are simplified and thin as compared with the case where the optical wavelength conversion sheet and the optical member are arranged separately and independently. A backlight device can be obtained. That is, when the light wavelength conversion sheet and the optical member are arranged separately and independently, since an air interface exists between the light wavelength conversion sheet and the optical member, a relatively large void is created in the backlight device. It takes. On the other hand, in the present embodiment, since the light wavelength conversion layer 11 and the optical member 51 are integrated, there is no air interface between the light wavelength conversion layer 11 and the optical member 51. This makes it possible to obtain a simplified thin backlight device.

A light emitting body such as a light emitting diode also emits heat when it emits light. Therefore, normally, when the light wavelength conversion unit is incorporated in the light source or when the light wavelength conversion member is arranged at a position close to the light source, the light wavelength conversion unit is covered in order to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, the light transmissive particles 19 of the light wavelength conversion particles 17 in the light wavelength conversion unit 164 and the light wavelength conversion layer 182 provide heat resistance in the light wavelength conversion unit 164 and the light wavelength conversion layer 182. Since the moisture resistance and heat resistance can be improved, deterioration of the quantum dots 18 can be suppressed without covering the light wavelength conversion unit 164 and the light wavelength conversion layer 182 with a barrier member.

In order to explain the present invention in detail, examples will be given below, but the present invention is not limited to these descriptions.

<< Manufacture of light wavelength conversion particles >>
Light wavelength conversion particles were obtained according to the following procedure.
(Light wavelength conversion particle 1)
In a polymerization vessel having a stirrer, first, 50 parts by mass of bisphenol A type epoxy resin (product name "jER828", manufactured by Mitsubishi Chemical Corporation), tetraethylene glycol bis (3-mercaptopropionate) (product name "EGMP-"). 4 ”, SC Organic Chemical Co., Ltd.) 50 parts by mass, epoxy curing accelerator (product name“ (2,4,6-tris (dimethylaminomethyl) phenol) ”, manufactured by Tokyo Kasei Kogyo Co., Ltd.) 1 part by mass, green light emission Quantum dot (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) 1.0 part by mass, red light emitting quantum dot (product name "CdSe / ZnS" 610 ”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass of a composition for light wavelength conversion particles was added, and a dispersant was added thereto as a poor solvent. 10 parts by mass of polyvinyl alcohol was dissolved in 900 parts by mass of ion-exchanged water. Then, the composition for light wavelength conversion particles was finely dispersed as droplets in a poor solvent by stirring with a stirring device at a stirring speed of 400 rpm for 10 minutes. Subsequently, stirring by the stirrer is continued at a stirring speed of 400 rpm, the temperature of the reaction solution containing the composition for light wavelength conversion particles and the poor solvent is raised to 60 ° C., and the temperature of the reaction solution is 60 ° C. Suspension polymerization was carried out over 3 hours, then the temperature of the reaction solution was raised to 80 ° C., and the reaction solution was stirred at 80 ° C. for 3 hours to obtain a particulate polymer. rice field. Then, the reaction solution containing the polymer in the polymerization vessel was cooled to room temperature while stirring with a stirrer. Next, the reaction solution was suction-filtered, the filtration residue was washed with ion-exchanged water, and then the solution was removed to obtain light wavelength-converted particles 1. In the light wavelength conversion particles 1, green light emitting quantum dots and red light emitting quantum dots were included in the resin particles, and the average particle size of the light wavelength conversion particles 1 was 3.3 μm. The average particle size of the light wavelength conversion particles 1 was determined by measuring the particle size of 20 light wavelength conversion particles 1 with a transmission electron microscope and calculating the average value thereof. The average particle diameters of the following light wavelength conversion particles 2 to 7 were also determined to be the same as those of the light wavelength conversion particles 1.

(Light wavelength conversion particle 2)
Except for using 50 parts by mass of 2-methacryloxyethyl acid phosphate (product name "Light Ester P-2M", manufactured by Kyoeisha Chemical Co., Ltd.) instead of tetraethylene glycol bis (3-mercaptopropionate). Light wavelength conversion particles 2 were obtained by the same procedure as for light wavelength conversion particles 1. In the light wavelength conversion particles 2, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 2 was 3.6 μm.

(Light wavelength conversion particle 3)
By the same procedure as for light wavelength conversion particles 1, except that 50 parts by mass of stearylamine (product name "Farmin 80", manufactured by Kao Corporation) was used instead of tetraethylene glycol bis (3-mercaptopropionate). , Light wavelength conversion particles 3 were obtained. In the light wavelength conversion particles 3, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 3 was 3.4 μm.

(Light wavelength conversion particle 4)
Except for using 50 parts by mass of ω-carboxy-polycaprolactone mono (meth) acrylate (product name "M-5300", manufactured by Toagosei Co., Ltd.) instead of tetraethylene glycol bis (3-mercaptopropionate). , The light wavelength conversion particle 4 was obtained by the same procedure as that of the light wavelength conversion particle 1. In the light wavelength conversion particles 4, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 4 was 3.6 μm.

(Light wavelength conversion particle 5)
In a polymerization vessel having a stirrer, first, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), tetraethylene glycol bis (3-mercaptopropionate) (Product name "EGMP-4", manufactured by SC Organic Chemical Co., Ltd.) 50 parts by mass, green light emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) 1.0 part by mass, red light emitting quantum dot (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass , And a thermal radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.). As a result, 10 parts by mass of polyvinyl alcohol as a dispersant was dissolved in 900 parts by mass of ion-exchanged water. Then, the composition for light wavelength conversion particles was finely dispersed as droplets in a poor solvent by stirring with a stirring device at a stirring speed of 400 rpm for 10 minutes. Subsequently, stirring by the stirrer is continued at a stirring speed of 400 rpm, the temperature of the reaction solution containing the composition for light wavelength conversion particles and the poor solvent is raised to 50 ° C., and the temperature of the reaction solution is 50 ° C. After that, in order to completely inactivate the thermal radical initiator, the temperature of the reaction solution was raised to 80 ° C., and the temperature of the reaction solution was 80 ° C. Stirring for hours gave a particulate polymer. Then, the reaction solution containing the polymer in the polymerization vessel was cooled to room temperature while stirring with a stirrer. Next, the reaction solution was suction-filtered, the filtration residue was washed with ion-exchanged water, and then the solution was removed to obtain light wavelength-converted particles 5. In the light wavelength conversion particles 5, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 5 was 3.0 μm.

(Light wavelength conversion particle 6)
First, 0.2 parts by mass of green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm) and red emission quantum dots (product name). "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 0.2 mass was prepared. After preparing the green emission quantum dots and the red emission quantum dots, the surfaces of the green emission quantum dots and the red emission quantum dots are covered with dodecylamine, and these quantum dots are put into a toluene solution (0.4 mL, 1.5 μM / L). Distributed. Next, tetraethoxysilane (TEOS, 10 μL) was added to this solution, and the mixture was stirred for 3 hours to prepare an organic solution 1.

On the other hand, 3-mercaptopropyltrimethoxysilane (MPS, 1 μL) was mixed with ethanol (25 mL) and aqueous ammonia (4 mL, ammonia concentration 10 wt%) to prepare an aqueous solution 2.

Then, when the organic solution 1 and the aqueous solution 2 were mixed and stirred for 3 hours, the green emission quantum dots and the red emission quantum dots moved to the aqueous phase, and further, an aggregate of the green emission quantum dots and the red emission quantum dots in the aqueous phase. Was formed. The aggregate was removed by centrifugation.

Finally, 0.5 mL of the aqueous solution in which the above aggregates were dispersed was taken out, ethanol (8 mL) and aqueous ammonia (0.1 mL, 25 wt%) were added, and TEOS (14 μL) was further added. As a result, light wavelength conversion particles 6 having an average particle diameter of 50 nm in which green emission quantum dots and red emission quantum dots were encapsulated in silica glass particles were obtained.

(Light wavelength conversion particle 7)
Light wavelength conversion particles 7 were obtained by the same procedure as for light wavelength conversion particles 1 except that tetraethylene glycol bis (3-mercaptopropionate) was not used. In the light wavelength conversion particles 7, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 7 was 3.2 μm.

<< Adjustment of composition containing light wavelength conversion particles >>
Each component was blended so as to have the composition shown below to obtain a composition containing light wavelength conversion particles.
(Composition containing light wavelength conversion particles 1)
-Light wavelength conversion particles 1:20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 2)
-Light wavelength conversion particles 1:20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Alumina particles (light-scattering particles, product name "DAM-03", electricity Chemical Industry Co., Ltd., average particle size 4 μm): 10 parts by mass ・ Radical polymerization initiator (1-hydroxycyclohexylphenylketone, product name “Irgacure (registered trademark) 184”, BASF Japan Co., Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 3)
-Light wavelength conversion particles 2: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 4)
-Light wavelength conversion particles 3: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 5)
-Light wavelength conversion particles 4: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 6)
-Light wavelength conversion particles 1:20 parts by mass-Silicone (product name "OE-6331", manufactured by Toray Dow Corning): 80 parts by mass

(Composition containing light wavelength conversion particles 7)
-Light wavelength conversion particles 5:20 parts by mass-Silicone (product name "OE-6331", manufactured by Toray Dow Corning): 80 parts by mass

(Composition containing light wavelength conversion particles 8)
-Light wavelength conversion particles 6: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 9)
-Light wavelength conversion particles 5:20 parts by mass-Alicyclic epoxy resin (product name "Selokiside 2021P", manufactured by Daicel Chemical Industry Co., Ltd.): 80 parts by mass-Cationic polymerization initiator (product name "Sun Aid SI-60L", 3) Shin Kagaku Kogyo Co., Ltd.): 1 part by mass

(Composition containing light wavelength conversion particles 10)
-Light wavelength conversion particles 7:20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

<Preparation of composition for overcoat layer>
Each component was blended so as to have the composition shown below to obtain a composition for an overcoat layer.
(Composition 1 for overcoat layer)
-Zinc acrylate (product name "ZN-DA" manufactured by Nippon Catalyst Co., Ltd.): 25 parts by mass-Mixed mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", Toa Synthetic Co., Ltd.): 5 parts by mass, methanol: 70 parts by mass, photopolymerization initiator (1-hydroxycyclohexylphenylketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass"

(Composition for overcoat layer 2)
-A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", manufactured by Toa Synthetic Co., Ltd.): 30 parts by mass-Methanol: 70 parts by mass-Photopolymerization initiator (1) -Hydroxycyclohexylphenylketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass

<Preparation of composition for light diffusion layer>
Each component was blended so as to have the composition shown below to obtain a composition 1 for a light diffusion layer.
(Composition for light diffusion layer 1)
-Pentaerythritol triacrylate: 99 parts by mass-light scattering particles (crosslinked polystyrene resin particles, product name "SBX-4", manufactured by Sekisui Kasei Kogyo Co., Ltd., average particle diameter 4 μm): 158 parts by mass-photopolymerization initiator (1-Hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan, Inc.): 1 part by mass / solvent (methylisobutylketone: cyclohexanone = 1: 1 (mass ratio)): 170 parts by mass

<Example 1>
The composition for the light diffusion layer is applied to one side of two polyethylene terephthalate (PET) base materials (product name "Lumilar T60", manufactured by Toray Industries, Inc.) as a light transmissive base material having a size of 7 inches and a thickness of 50 μm. , Applied to form a coating film. Next, the solvent in the coating film was evaporated by passing dry air at 80 ° C. for 30 seconds to dry the formed coating film. Then, the coating film was cured by irradiating ultraviolet rays so that the integrated light amount was 500 mJ / cm ² , to form a light diffusing layer having a thickness of 10 μm, and forming a PET substrate with a light diffusing layer.

Next, the light wavelength conversion particle-containing composition 1 was applied to a surface of the PET substrate with a light diffusion layer opposite to the surface on the light diffusion layer side to form a coating film. Then, the other PET substrate with a light diffusing layer was laminated on the coating film so that the surface of the PET substrate with a light diffusing layer on the other side opposite to the surface on the light diffusing layer side was in contact with the coating film. In this state, the coating film is cured by heating at 100 ° C. to form an optical wavelength conversion layer having a film thickness of 100 μm, and the optical wavelength conversion layer and two PET substrates with a light diffusion layer are integrated. It became. As a result, the optical wavelength conversion sheet according to Example 1 was obtained.

<Examples 2 to 5 and 8 and Comparative Example 2>
In Examples 2 to 5 and 8 and Comparative Example 2, the same as in Example 1 except that each light wavelength conversion particle-containing composition shown in Table 2 was used instead of the light wavelength conversion particle-containing composition 1. To prepare an optical wavelength conversion sheet.

<Example 6>
In Example 6, the light wavelength conversion particle-containing composition 6 is used instead of the light wavelength conversion particle-containing composition 1, and the coating film is cured by heating at 100 ° C. for 5 hours to form a light wavelength conversion layer. An optical wavelength conversion sheet was obtained in the same manner as in Example 1 except that it was formed.

<Example 7>
In Example 7, a light wavelength conversion sheet was obtained in the same manner as in Example 6 except that the light wavelength conversion particle-containing composition 5 was used instead of the light wavelength conversion particle-containing composition 6.

<Comparative example 1>
In Comparative Example 1, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer. A light wavelength conversion sheet was obtained in the same manner as in Example 1 except for the above.

<Example 9>
The light wavelength conversion particle-containing composition 1 was applied to one surface of a 50 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form an optical wavelength conversion layer. Then, the composition 1 for the overcoat layer was applied to the surface of the light wavelength conversion layer opposite to the surface on the PET substrate side to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. Next, after peeling off the PET substrate, the composition 1 for the overcoat layer was applied to the surface of the light wavelength conversion layer opposite to the surface on the overcoat layer side to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. As a result, an optical wavelength conversion sheet composed of an optical wavelength conversion layer and an overcoat layer formed on both sides of the optical wavelength conversion layer was obtained.

<Example 10>
In Example 10, an optical wavelength conversion sheet was obtained in the same manner as in Example 9 except that the composition 2 for the overcoat layer was used instead of the composition 1 for the overcoat layer.

<Comparative example 3>
In Comparative Example 3, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer. Except for the above, an optical wavelength conversion sheet was obtained in the same manner as in Example 9.

<Comparative example 4>
In Comparative Example 4, a light wavelength conversion sheet was produced in the same manner as in Example 9 except that the light wavelength conversion particle-containing composition 10 was used instead of the light wavelength conversion particle-containing composition 1.

<Example 11>
A prism layer composition containing urethane acrylate is uniformly applied to one surface of a 100 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a prism layer composition. A coating film was formed to form a laminate for a prism sheet. Then, the traveling speed of the prism sheet laminate is such that the coating film of the lens layer composition is on the molding mold side in the rotating molding mold having recesses having a shape opposite to the desired unit prism shape. The shape of the unit prism is formed on the coating film of the prism layer composition by supplying at 20 m / min with a molding die, and light such as ultraviolet rays is applied to the coating film of the prism layer composition via the PET substrate. Irradiation was performed to cure the coating film of the composition for the prism layer. Finally, the cured coating film of the prism layer composition was peeled off from the molding mold together with the PET base material to obtain a prism sheet having a prism layer formed on one surface of the PET base material. The prism layers are arranged side by side on the sheet-shaped main body and each of them extends in a direction intersecting the arrangement direction, the apex angle is 90 °, the width is 47 μm, and the height is high. It had a plurality of triangular columnar unit prisms having a height of 30 μm.

Next, the light wavelength conversion particle-containing composition 1 was applied to the surface of the prism sheet opposite to the surface of the PET substrate on the prism layer side to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form an optical wavelength conversion layer having a thickness of 100 μm integrated with the prism sheet. As a result, the optical wavelength conversion sheet according to Example 11 was obtained.

<Comparative example 5>
In Comparative Example 5, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer. Except for the above, an optical wavelength conversion sheet was obtained in the same manner as in Example 11.

<Comparative Example 6>
In Comparative Example 6, a light wavelength conversion sheet was produced in the same manner as in Example 11 except that the light wavelength conversion particle-containing composition 10 was used instead of the light wavelength conversion particle-containing composition 1.

<Example 12>
First, two barrier films were prepared by the following method. In a high-frequency sputtering apparatus, by applying a high-frequency power of 13.56 MHz and a power of 5 kW to the electrodes, a discharge is generated in the chamber, and polyethylene terephthalate as a light-transmitting substrate having a size of 7 inches and a thickness of 50 μm is generated. A silica-deposited layer made of a target substance (silica), having a thickness of 50 nm and a refractive index of 1.46, was formed on one side of a (PET) base material (product name “Lumilar T60”, manufactured by Toray Co., Ltd.). As a result, two barrier films having a silica-deposited layer formed on one surface of the PET base material were formed.

Next, the composition 1 for the light diffusion layer was applied to the surface of both barrier films opposite to the surface on the silica-deposited layer side to form a coating film. Next, the solvent in the coating film was evaporated by passing dry air at 80 ° C. for 30 seconds to dry the formed coating film. Then, an ultraviolet ray was irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form a light diffusing layer having a thickness of 10 μm, and a barrier film with a light diffusing layer was formed.

Next, the light wavelength conversion particle-containing composition 1 was applied to the silica-deposited layer side of one of the barrier films with a light diffusion layer to form a coating film. Then, the other barrier film with a light diffusion layer was laminated on the surface of the silica-deposited layer of the barrier film with a light diffusion layer in the coating film so that the silica vapor deposition layer was in contact with the surface. In this state, ultraviolet rays are irradiated so that the integrated light amount is 500 mJ / cm ² , and the coating film is cured to form an optical wavelength conversion layer having a thickness of 100 μm in close contact with both barrier films with light diffusion layers. Formed. As a result, the optical wavelength conversion sheet according to Example 12 was obtained.

<Comparative Example 7>
In Comparative Example 7, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer. Except for the above, an optical wavelength conversion sheet was obtained in the same manner as in Example 12.

<Comparative Example 8>
In Comparative Example 8, a light wavelength conversion sheet was obtained in the same manner as in Example 12 except that the light wavelength conversion particle-containing composition 10 was used instead of the light wavelength conversion particle-containing composition 1.

<Example 13>
The light wavelength conversion particle-containing composition 6 was filled in the opening of the reflection member of the blue light emitting diode having an emission peak wavelength of 450 nm. Then, by heating at 100 ° C. for 5 hours, the filler was cured to obtain a light source according to Example 13 including an optical wavelength conversion unit filled in the opening of the reflection member of the blue light emitting diode.

<Comparative Example 9>
In Comparative Example 9, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the filling was cured by heating at 100 ° C. to form a light wavelength conversion unit. A light source was obtained in the same manner as in Example 13 except for the above.

<Example 14>
The light wavelength conversion particle-containing composition 1 was applied to the light entering surface of the light guide plate of the backlight device of Kindle Fire (registered trademark) HDX7, which will be described later, to form a coating film. Then, by irradiating ultraviolet rays so that the integrated light amount is 500 mJ / cm ² and curing the coating film, an optical wavelength conversion layer is formed on the light entry surface of the light guide plate, and the optical plate according to Example 14 is formed. Got

<Comparative Example 10>
In Comparative Example 10, the light wavelength conversion particle-containing composition 9 was used instead of the light wavelength conversion particle-containing composition 1, and the coating film was cured by heating at 100 ° C. to form a light wavelength conversion layer. An optical plate was obtained in the same manner as in Example 14 except for the above.

<Comparative Example 11>
In Comparative Example 11, an optical plate was obtained in the same manner as in Example 14 except that the light wavelength conversion particle-containing composition 10 was used instead of the light wavelength conversion particle-containing composition 1.

<Confirmation of specific elements and carboxylic acids in light-transmitting particles>
It was confirmed whether or not the above-mentioned specific element or carboxylic acid was detected in the resin particles in the light wavelength conversion particles 1 to 5 and 7. Specifically, for the optical wavelength conversion particles 1, 3, 5, and 7, an energy dispersive X-ray analyzer (product name "JEM-2800" ( ^{equipped with 100 mm 2} silicon drift detector (SDD)), JEOL Ltd. At any position on the surface or inside of the resin particles at a distance of 3 nm or more from the surface of the shell of the quantum dots under the conditions of an acceleration voltage of 100 kV and a measurement time of 30 seconds. It was confirmed whether at least one of the elements was detected. For the light wavelength conversion particles 4 and 7, an infrared microscope (product name "Nicolet iN10", manufactured by Thermo Fisher Scientific Co., Ltd.) is used to surface or inside the resin particles 3 nm or more away from the surface of the quantum dot shell. It was confirmed whether or not the carboxylic acid was detected at any position of. The confirmation criteria are as follows.
◯: Any of sulfur element, phosphorus element, nitrogen element and carboxylic acid was detected.
X: None of sulfur element, phosphorus element, nitrogen element and carboxylic acid was detected.

<Measurement of content of specific elements>
The content of specific elements contained in the resin particles of the optical wavelength conversion particles 1, 3, 5 and 7 is measured using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). bottom.

<Measurement of refractive index of surface of light wavelength conversion particles and binder resin>
The refractive indexes of the light wavelength conversion particles and the binder resin were measured in the light wavelength conversion sheet, the light source, and the optical plate according to the above Examples and Comparative Examples, respectively. Specifically, in the light wavelength conversion sheet, 10 pieces of the binder resin are cut out from the light wavelength conversion layer, and the refractive index of the binder resin is cut out from the cut out 10 pieces by the Becke method using a refractive index standard solution. Was measured, and the average value of 10 measured refractive indexes of the binder resin was taken as the refractive index of the binder resin. Further, in the optical wavelength conversion sheet, a fragment in which a part of the surface of the optical wavelength conversion particles is exposed from the binder resin is cut out from the optical wavelength conversion layer, and the surface of the cut out fragment is surfaced by the Becke method using a refraction standard solution. The refractive index of the surface of the 10 exposed light wavelength-converting particles was measured, and the average value of 10 of the surface refractive index of the measured light wavelength-converting particle was taken as the surface refractive index of the light wavelength-converting particle. For the light sources and optical plates according to the above Examples and Comparative Examples, the refractive indexes of the light wavelength conversion particles and the binder resin were measured in the same manner as described above.

<Measurement of optical wavelength conversion efficiency>
The light wavelength conversion efficiency was measured in the light wavelength conversion sheet, the light source, and the optical plate according to the above Examples and Comparative Examples. Specifically, first, prepare a Kindle Fire (registered trademark) HDX7 backlight device, and use a spectroradiometer (product name "SR-UL2", manufactured by Topcon) to emit light from this backlight device. The spectral spectrum of was obtained. This backlight device includes a blue light emitting diode having an emission peak wavelength of 450 nm, a light guide plate, a first prism sheet, and a second prism sheet in this order. Next, the light wavelength conversion sheet, the light source, and the optical plate according to the above-described Examples and Comparative Examples, which have not been subjected to the heat resistance test or the moisture-heat resistance test, are incorporated into the backlight, respectively, and from the backlight device in the same manner as described above. The spectral spectrum of the emitted light was obtained.

In Examples 1 to 9 and 12 and Comparative Examples 1 to 4, 7 and 8, the light guide plate is arranged so that the blue light emitting diode side is the light entry surface, and Examples 1 to 9 are arranged on the light emission surface of the light guide plate. , 12, and the light wavelength conversion sheet, the first prism sheet, and the second prism sheet according to Comparative Examples 1 to 4, 7, and 8 were arranged in this order, and the light wavelength conversion sheet was incorporated into the backlight device. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the first prism sheet.

In Example 11 and Comparative Examples 5 and 6, the light guide plate is arranged so that the blue light emitting diode side is the light entrance surface, and the prism surface of the prism sheet is on the light emission side of the light guide plate. The light wavelength conversion sheet and the second prism sheet according to Example 11 and Comparative Examples 5 and 6 were arranged in this order, and the light wavelength conversion sheet was incorporated into the backlight device. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the prism sheets in the optical wavelength conversion sheets according to Example 11 and Comparative Examples 5 and 6.

In Example 13 and Comparative Example 9, the blue light emitting diode is replaced with the light source according to Example 13 and Comparative Example 9, and the light guide plate is arranged so that the light source side is the light incoming surface and is on the light emitting surface of the light guide plate. The first prism sheet and the second prism sheet were arranged in this order, and the light source was incorporated into the backlight device.

In Example 14 and Comparative Examples 10 and 11, the light guide plate is replaced with the optical plate according to Example 14 and Comparative Examples 10 and 11, and the optical plate is arranged so that the blue light emitting diode side serves as the optical wavelength conversion layer. The first prism sheet and the second prism sheet were arranged in this order on the light emitting surface of the optical plate, and the optical plate was incorporated into the backlight device.

Then, from the spectral spectrum obtained from each backlight device, the integrated value of the blue light spectrum, the integrated value of the green light spectrum (spectrum in the wavelength range of 480 nm or more and less than 590 nm), and the red light spectrum (wavelength of 590 nm or more and 750 nm or less). The integrated value of the region spectrum) was calculated. For each of the integrated value of the green light spectrum and the integrated value of the red light spectrum measured by using the backlight device incorporating the light wavelength conversion sheet, the light source, and the optical plate according to the above-mentioned Examples and Comparative Examples, the above-mentioned Example and The light wavelength conversion efficiency was measured by dividing by the integrated value of the blue light spectrum measured using the backlight device before incorporating the light wavelength conversion sheet, the light source, and the optical plate according to the comparative example.

<Measurement of water vapor permeability and oxygen permeability>
The water vapor transmittance and the oxygen transmittance were measured in the light wavelength conversion sheets according to Examples 1 to 12 and Comparative Examples 1 to 8, respectively. The water vapor transmittance of the optical wavelength conversion sheet is 40 ° C. and 90% relative humidity using a water vapor transmittance measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON) in accordance with JIS K7129: 2008. It was measured under the conditions of. The oxygen transmittance of the optical wavelength conversion sheet is 23 ° C. relative to the oxygen gas transmittance measuring device (product name "OX-TRAN 2/21", manufactured by MOCON) in accordance with JIS K7126: 2006. It was measured under the condition of 90% humidity. The water vapor permeability and the oxygen permeability were taken as the average value of the values obtained by measuring each of the three times.

<Measurement of brightness maintenance rate after heat resistance test>
The light wavelength conversion sheet, the light source, and the optical plate according to the above Examples and Comparative Examples are subjected to a heat resistance test in which the light wavelength conversion sheet, the light source, and the optical plate are left in an environment of 80 ° C. for 500 hours to perform light wavelength conversion. The maintenance rate of the brightness after the heat resistance test with respect to the brightness before the heat resistance test on the sheet, the light source, and the optical plate was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device is prepared, and the light wavelength conversion sheet before the heat resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8 is used for the above-mentioned light wavelength conversion efficiency. Each of them was incorporated into this backlight device in the same manner as the measurement of.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated to one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral emission brightness meter (product name "CS2000", manufactured by Konica Minolta). The measurement was performed under the condition of an angle of 1 °.

Next, the light wavelength conversion sheet before the heat resistance test was removed from the backlight device, and the light wavelength conversion sheet was subjected to a heat resistance test in which the light wavelength conversion sheet was left in an environment of 80 ° C. for 500 hours. Then, the light wavelength conversion sheet after the heat resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the optical wavelength conversion sheet using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

From these measured brightnesss, the maintenance rate of the brightness after the heat resistance test with respect to the brightness before the heat resistance test was determined. The brightness retention rate is such that the brightness maintenance rate is A, the brightness of the light emitted from the light emitting surface of the backlight device before the heat resistance test is B, and the brightness of the light emitted from the light emitting surface of the backlight device after the heat resistance test is B. Was C, and it was calculated by the following formula.
A = C / B x 100

In Example 13 and Comparative Example 9, the retention rate of the brightness after the heat resistance test was determined with respect to the brightness before the heat resistance test in the same manner as described above. However, in Example 13 and Comparative Example 9, a heat resistance test was performed on the light source, and this light source was incorporated into the backlight device in the same manner as in the measurement of the light wavelength conversion efficiency.

In Example 14 and Comparative Examples 10 and 11, the retention rate of the brightness after the heat resistance test was determined with respect to the brightness before the heat resistance test in the same manner as described above. However, in Example 14 and Comparative Examples 10 and 11, the optical plate was subjected to a heat resistance test, and the optical plate was incorporated into the backlight device in the same manner as in the measurement of the optical wavelength conversion efficiency.

<Measurement of brightness maintenance rate after moisture resistance test>
In the light wavelength conversion sheet, the light source, and the optical plate according to the above Examples and Comparative Examples, a moisture and heat resistance test was performed in which the light wavelength conversion sheet, the light source, and the optical plate were left in an environment of 60 ° C. and 90% relative humidity for 500 hours. Then, the maintenance rate of the brightness after the moisture resistance test with respect to the brightness before the moisture resistance test on the light wavelength conversion sheet, the light source, and the optical plate was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device is prepared, and the light wavelength conversion sheet before the moist heat resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8 is used for the above-mentioned light wavelength conversion efficiency. Each of them was incorporated into this backlight device in the same manner as the measurement of.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated to one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured from the thickness direction of the light wavelength conversion sheet using a spectral emission brightness meter (product name "CS2000", manufactured by Konica Minolta). The measurement was performed under the condition of an angle of 1 °.

Next, the light wavelength conversion sheet before the moisture heat resistance test is removed from the backlight device, and the light wavelength conversion sheet is subjected to a heat resistance test in which the light wavelength conversion sheet is left in an environment of 60 ° C. and 90% relative humidity for 500 hours. rice field. Then, the light wavelength conversion sheets after the moisture resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8 were incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ) Was measured from the thickness direction of the optical wavelength conversion sheet using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1 °.

From these measured luminances, the retention rate of the luminance after the moisture resistance test was determined with respect to the luminance before the moisture resistance test. The brightness retention rate is such that the brightness maintenance rate is D, the brightness of the light emitted from the light emitting surface of the backlight device before the moisture resistance test is E, and the brightness of the light emitted from the light emitting surface of the backlight device after the moisture resistance test is E. Was F, and it was calculated by the following formula.
D = F / E × 100

In Example 13 and Comparative Example 9, the retention rate of the brightness after the moisture resistance test was determined with respect to the brightness before the moisture resistance test in the same manner as described above. However, in Example 13 and Comparative Example 9, a moist heat resistance test was performed on the light source, and this light source was incorporated into the backlight device in the same manner as in the measurement of the light wavelength conversion efficiency.

In Example 14 and Comparative Examples 10 and 11, the retention rate of the brightness after the moisture resistance test was determined with respect to the brightness before the moisture resistance test in the same manner as described above. However, in Example 14 and Comparative Examples 10 and 11, the optical plate was subjected to a moist heat resistance test, and the optical plate was incorporated into the backlight device in the same manner as in the measurement of the optical wavelength conversion efficiency.

<Evaluation of point-shaped brightness defects>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8, there is a point-like brightness defect on the light emitting surface at the time of light emission in the backlight device. The presence was visually observed and evaluated. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8, similarly, a point is formed on the light emitting surface at the time of light emission in the backlight device. It was visually observed and evaluated whether or not there was a defect in the brightness of the shape. The evaluation criteria are as follows.
◯: No point-shaped luminance defect was confirmed.
Δ: Several point-shaped luminance defects were confirmed.
X: Many point-shaped luminance defects were confirmed.

<Measurement of deterioration width of the peripheral edge of the optical wavelength conversion sheet>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8, the brightness distribution on the light emitting surface at the time of light emission in the backlight device is determined by the light wavelength. The measurement was performed from the thickness direction of the conversion sheet using a 2D color luminance meter (product name "UA-200", manufactured by Topcon Techno House Co., Ltd.). Then, from the measured brightness distribution of the light emitting surface, the position of the light emitting surface (luminance 80% position) at which the brightness is 80% with respect to the brightness of the central portion of the light emitting surface is obtained, and is closest to the brightness 80% position on the light emitting surface. The shortest distance from the edge to the position where the brightness is 80% was obtained. Then, the shortest distance was randomly obtained for 20 places, and the average value of the shortest distances at these 20 places was taken as the deterioration width of the peripheral portion of the optical wavelength conversion sheet. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test according to Examples 1 to 12 and Comparative Examples 1 to 8, the brightness distribution of the light emitting surface is measured in the same manner to emit light. Find the position of the light emitting surface (luminance 80% position) where the brightness is 80% of the brightness of the central part of the surface, and find the shortest distance from the end closest to the brightness 80% position on the light emitting surface to the brightness 80% position. rice field.

The results are shown in Tables 1 to 3 below.

The results will be described below. As can be seen from Table 2, in the light wavelength conversion sheet according to Examples 1 to 12, the light source according to Example 13, and the optical plate according to Example 14, the refractive index of the surface of the light wavelength conversion particles is the binder resin. The optical wavelength conversion sheet according to Comparative Examples 1, 3, 5 and 7, and the light source according to Comparative Example 9 are compared. The light wavelength conversion efficiency was higher than that of the optical plate according to Example 10.

Further, as can be seen from Table 3, in the light wavelength conversion sheet according to Examples 1 to 11, resin particles containing at least one of the above-mentioned specific element and carboxylic acid are used, or glass particles are used. Compared with the light wavelength conversion sheet according to Comparative Examples 2, 4 and 6 using the resin particles containing neither the specific element nor the carboxylic acid, the brightness retention rate after the heat resistance test and the moisture heat resistance test was higher. .. Further, since the light wavelength conversion sheet according to Example 12 uses resin particles containing at least one of the above-mentioned specific element and carboxylic acid, resin particles containing neither of the above-mentioned specific element or carboxylic acid can be used. Compared with the light wavelength conversion sheet according to Comparative Example 8 used, the brightness retention rate after the heat resistance test and the moisture heat resistance test was higher. In the light source according to Example 13, since resin particles containing at least one of the above-mentioned specific element and carboxylic acid were used, the brightness retention rate after the heat resistance test and the moisture heat resistance test was high. Since the optical plate according to Example 14 uses resin particles containing at least one of the above-mentioned specific element and carboxylic acid, a comparative example using resin particles containing neither of the above-mentioned specific element or carboxylic acid. Compared with the optical plate according to No. 11, the brightness retention rate after the heat resistance test and the moisture heat resistance test was higher. This means that when resin particles or glass particles containing any of the above-mentioned specific element and carboxylic acid are used, excellent heat resistance and moist heat resistance can be obtained, and deterioration of quantum dots can be suppressed.

Since the barrier film was not used in the light wavelength conversion sheets according to Examples 1 to 11 and Comparative Examples 1 to 6, no punctate luminance defect was confirmed. Further, in the light wavelength conversion sheet according to Example 12 and Comparative Example 7, a barrier film is used, but since resin particles containing at least one of the above-mentioned specific element and carboxylic acid are used, they are point-shaped. No brightness defects were found. On the other hand, in the light wavelength conversion sheet according to Comparative Example 8 using the resin particles containing neither the specific element nor the carboxylic acid, a point-like luminance defect was confirmed. This means that the specific element or carboxylic acid in the resin particles can suppress the deterioration of the quantum dots.

In the light wavelength conversion sheets according to Examples 1 to 12, since resin particles or glass particles containing at least one of the above-mentioned specific element and carboxylic acid were used, deterioration of the peripheral portion was suppressed. On the other hand, in the light wavelength conversion sheet according to Comparative Example 8 using the resin particles containing neither the specific element nor the carboxylic acid, deterioration of the peripheral portion was confirmed. This means that even in an environment where the quantum dots are exposed to a large amount of oxygen or water vapor such as the peripheral portion, the specific element or carboxylic acid in the resin particles or the glass particles can suppress the deterioration of the quantum dots. ing. Further, in the light wavelength conversion sheet according to Comparative Example 8, the deterioration of the central portion was relatively suppressed by the barrier film, but the deterioration of the peripheral portion was not suppressed.

Further, in the light wavelength conversion sheets according to Examples 9 and 10, a scratch test was performed on the overcoat layer, and the vertical force and the horizontal force at that time were measured. As a result, the light wavelength conversion sheet according to Example 9 was found. The vertical force was 21 μN and the horizontal force was -11 μN, and the optical wavelength conversion sheet according to Example 10 had a vertical force of 11 μN and a horizontal force of -6 μN. These overcoat layers became dense films and had an ability to prevent the light wavelength conversion layer from exposure to the atmosphere. However, in terms of the ability to prevent the light wavelength conversion layer from exposure to the atmosphere, the light wavelength conversion sheet according to Example 9 It can be said that the overcoat layer is higher than the overcoat layer of the optical wavelength conversion sheet according to Example 10. The scratch test is performed using a nanoindentation device (product name "TI950 TriboIndenter", manufactured by HYSITRON) from the cross section of the overcoat layer to the inside of the overcoat layer (Cube Corner: Ti037_110410 (12)). ) Is pushed in by 50 nm, the depth is kept constant, and the indenter is moved horizontally at a moving speed of 4 μm / min for 30 seconds, and the vertical force (load) and horizontal force at that time are measured and measured. The average value of the vertical force and the horizontal force is obtained, and the average value of the five average values of the vertical force (five times average value) obtained by repeating this scratch test five times is used as the vertical force, and the five horizontal forces are used. The average value of the average values (5 times average value) was defined as the horizontal force.

In the light wavelength conversion particles 1 to 5, the content of the specific element measured by fluorescent X-ray analysis was 0.5% by mass or more. On the other hand, in the light wavelength conversion particles 7, the specific content measured by fluorescent X-ray analysis was less than 0.5% by mass. In the light wavelength conversion particles 7, although the resin particles do not contain a specific element, the content of the specific element is not 0% by mass because the quantum dots themselves are specified. It is considered that this is because the element of was contained.

In the above example, CdSe is used as the core material of the green light emitting quantum dots and the red light emitting quantum dots, but even if a non-Cd material such as InP or InAs is used as the core material, the same result as in the above example is obtained. was gotten.

10, 30, 40, 50, 60, 70 ... Optical wavelength conversion sheet 11, 182 ... Optical wavelength conversion layer 17 ... Optical wavelength conversion particle 18 ... Quantum dot 19 ... Binder resin 20 ... Light scattering particle 80 ... Image display device 90 , 140, 150, 170 ... Backlight device 130 ... Display panel 160 ... Light source 164 ... Light wavelength conversion member 180 ... Optical plate

Claims (8)

An optical wavelength conversion member including at least an optical wavelength conversion unit.
A light wavelength conversion particle containing a binder resin and light-transmitting particles dispersed in the binder resin, wrapping the quantum dots and the quantum dots, and having a function of suppressing deterioration of the quantum dots. Including and
Refractive index of the surface of the optical wavelength conversion particles, much larger than the refractive index of the binder resin,
The light-transmitting particles are resin particles containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and carboxylic acids, and are materials constituting the surface of the light wavelength conversion particles. Is a light wavelength conversion member which is a resin constituting the resin particles. The light wavelength conversion member according to claim 1, wherein the light wavelength conversion unit is a light wavelength conversion layer, and the light wavelength conversion member is a light wavelength conversion sheet. The quantum dots include a core made of a first semiconductor compound, a shell made of a second semiconductor compound that covers the core and is different from the first semiconductor compound, and a ligand bound to the surface of the shell. , The optical wavelength conversion member according to claim 1 or 2. The light wavelength conversion member according to any one of claims 1 to 3, wherein the light wavelength conversion unit further includes light scattering particles. 40 ° C., water vapor transmission rate at a relative humidity of 90% 0.1g ^/ (m 2 · 24h) or higher and 23 ° C., the oxygen permeability at a relative humidity of 90% ^{0.1cm 3 / (m 2 · 24h} · atm ) The optical wavelength conversion member according to claim 2 , which satisfies at least one of the above. The light wavelength conversion member according to claim 2 , further comprising an optical member arranged on at least one surface side of the light wavelength conversion unit and integrated with the light wavelength conversion unit. Luminous body and
A backlight device comprising the light wavelength conversion member according to any one of claims 1 to 6, which receives light from the light emitter. An image display device including the light wavelength conversion member according to any one of claims 1 to 6 or the backlight device according to claim 7.

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