JP6841108B2 - 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 under consideration to incorporate an optical wavelength conversion member containing quantum dots into an image display device. 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.

As a method of incorporating the light wavelength conversion member into the backlight device, there is an on-edge method of incorporating the light wavelength conversion member between the light source and the light guide plate (see, for example, Patent Document 1). Since the quantum dots are deteriorated by moisture and oxygen and the luminous efficiency may be lowered, the quantum dots are currently enclosed in a glass tube in the on-edge type optical wavelength conversion member.

Japanese Unexamined Patent Publication No. 2013-218953

However, in the optical wavelength conversion member having a structure in which the quantum dots are enclosed in the glass tube as described above, the glass tube is easily damaged and the yield is inferior. Further, at present, it is desired to simplify the structure of the light wavelength conversion member.

The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide an optical wavelength conversion member capable of improving the yield and simplifying the structure, a backlight device provided with such an optical wavelength conversion sheet, and an image conversion device. ..

As a result of diligent research on the above-mentioned problems, the present inventors have made quantum dots into 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. It has been found that when the quantum dots are included in the particles or in the barrier particles, the deterioration of the quantum dots can be suppressed, so that an enclosed container such as a glass tube becomes unnecessary. The present invention has been completed based on such findings.

According to one aspect of the present invention, an optical member having a light entering surface and a light emitting surface, an optical wavelength conversion layer provided on the light entering surface side of the optical member and containing a light wavelength conversion particle and a binder resin, and a light wavelength conversion layer. The light wavelength conversion particles are encapsulated in the light transmissive 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 resin particles. A light wavelength that is at least one of a first light wavelength conversion particle containing a quantum dot, a light transmissive barrier particle, and a second light wavelength conversion particle containing a quantum dot included in the barrier particle. A conversion member is provided.

In the light wavelength conversion member, the light wavelength conversion layer may be in contact with the light incoming surface of the optical member, and the refractive index of the binder resin may be different from the refractive index of the optical member.

In the light wavelength conversion member, the light wavelength conversion layer is provided between the light wavelength conversion layer and the light entry surface of the optical member, is in contact with the light wavelength conversion layer and the light entry surface, and has the refractive index of the binder resin and the light input surface. A light transmitting layer different from the refractive index of the optical member may be further provided.

In the light wavelength conversion member, the light entering surface of the optical member is a side surface located between the light emitting surface and the back surface opposite to the light emitting surface, and the light emitting surface of the optical member is a front surface. It may have an uneven shape on the entry optical surface side.

In the light wavelength conversion member, the optical member may be a light guide plate.

In the light wavelength conversion member, the first light wavelength conversion particle may further include a coating layer covering the surface of the resin particles.

In the light wavelength conversion member, the coating layer may be a barrier layer that suppresses the permeation of water and oxygen.

In the light wavelength conversion member, the barrier particles may be inorganic oxide 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.

According to another aspect of the present invention, the light source and the light wavelength conversion member that receives light from the light source are provided, and the light wavelength conversion layer is located closer to the light source than the optical member. , A backlight device is provided.

According to another aspect of the present invention, there is provided an image display device including the backlight device and a display panel arranged on the light emitting side of the backlight device.

According to one aspect of the present invention, it is possible to obtain an optical wavelength conversion member capable of improving the yield and simplifying the structure. According to another aspect of the present invention, it is possible to provide a backlight device and an image display device provided with such a light wavelength conversion member.

It is a schematic block diagram of the light wavelength conversion member which concerns on embodiment. It is a partially enlarged view of the light wavelength conversion member of FIG. It is a ray tracing diagram of the light wavelength conversion member of FIG. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a partially enlarged view of the light wavelength conversion member of FIG. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a ray tracing diagram of the light wavelength conversion member of FIG. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a ray tracing diagram of the light wavelength conversion member of FIG. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion member which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion member 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.

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. FIG. 1 is a schematic configuration diagram of a light wavelength conversion member according to the present embodiment, FIG. 2 is a partially enlarged view of the light wavelength conversion member of FIG. 1, and FIG. 3 is a ray tracing of the light wavelength conversion member of FIG. It is a figure. 4, FIGS. 6, 8, 10 to 12 are schematic configuration views of other light wavelength conversion members according to the present embodiment, and FIG. 5 is a partially enlarged view of the light wavelength conversion member of FIG. FIG. 7 is a ray tracing diagram of the light wavelength conversion member of FIG. 6, FIG. 9 is a ray tracing diagram of the optical wavelength conversion member of FIG. 8, and FIG. 13 is an optical wavelength according to the present embodiment. It is a figure which shows typically the manufacturing process of a conversion member.

<<<<< Optical wavelength conversion member >>>>>
The light wavelength conversion member 10 shown in FIG. 1 includes an optical member 11 having an incoming light incident surface 11A and an outgoing light emitting surface 11B, and an optical wavelength conversion layer 12 provided on the light incoming surface 11A side of the optical member 11. .. The light wavelength conversion layer 12 shown in FIG. 1 is in contact with the light entry surface 11A of the optical member 11, but is a light transmission layer having light transmission between the light wavelength conversion layer and the light entry surface of the optical member. May intervene.

In the light wavelength conversion member 10, deterioration of the quantum dots 15 can be suppressed by the resin particles 16 described later, so that the water vapor transmittance (WVTR: Water Vapor Transmission Rate) at an arbitrary location at 40 ° C. and 90% relative humidity can be obtained. 0.1g ^/ (m 2 · 24h) may be equal to or greater than. 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.

In the optical wavelength conversion member 10, the resin particles 16 described later can suppress the deterioration of the quantum dots 15, so that the oxygen transmission rate (OTR: Oxygen Transmission Rate) at an arbitrary location at 23 ° C. and 90% relative humidity is 0. ^{.1cm 3 / (m 2 · 24h} · atm) may be equal to or greater than. The light wavelength conversion member 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.

40 ° C. in the optical wavelength conversion member 10, the 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 member 10, at a relative humidity of 90% oxygen permeability may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

<<< Optical member >>>
The "optical member" in the present specification has an incoming light surface and an outgoing light surface, and has optical characteristics (for example, polarization, light refraction, light scattering, light reflection, light transmission, and light absorption). , Photodiffractive property, luminous property, etc.), and is not particularly limited as long as it is a sheet (film) -shaped or plate-shaped member having optical properties. Examples of the optical member include a light guide plate, a lens sheet, a light diffusing plate, a reflective polarizing separation sheet, a polarizing plate, and the like. In the present embodiment, the case where the optical member 11 is a light guide plate will be described.

The optical member 11 as the light guide plate has a quadrangular shape in a plan view. One of the main surfaces of the optical member 11 is the light emitting surface 11B, and the main surface opposite to the light emitting surface 11B is the back surface 11C. Of the two side surfaces between the light emitting surface 11B and the back surface 11C. One side surface is an incoming light surface 11A. Light incident on the optical member 11 from the light entry surface 11A is guided in the optical member 11 in the direction (light guide direction) connecting the light entry surface 11A and the side surface 11D opposite to the light entry surface 11. , Is emitted from the light emitting surface 11B.

<<< Light wavelength conversion layer >>>
The light wavelength conversion layer 12 contains the light wavelength conversion particles 13 as the first light wavelength conversion particles and the binder resin 14. The light wavelength conversion particle 13 is a particle that converts the wavelength of incident light into another wavelength. The light wavelength conversion layer 12 may convert the wavelengths of all the incident light to other wavelengths, or may convert the wavelengths of some of the incident light to other wavelengths. The light wavelength conversion layer 12 may include a light wavelength conversion particle 22 and a light scattering particle as a second light wavelength conversion particle described later, in addition to the light wavelength conversion particle 13 and the binder resin 14.

The film thickness of the optical wavelength conversion layer 12 is preferably 200 μm or more and 5 mm or less. When the film thickness of the optical wavelength conversion layer 12 is within this range, it is suitable for weight reduction and miniaturization of the backlight device. For the film thickness of the optical wavelength conversion layer 12, a scanning electron microscope (SEM) is used to photograph a cross section of the optical wavelength conversion layer 12, and the film thickness of the optical wavelength conversion layer 12 is measured at 20 points in the image of the cross section. , The average value of the film thickness at the 20 points. It is more preferable that the upper limit of the average film thickness of the optical wavelength conversion layer 12 is less than 3 mm.

The light wavelength conversion layer 12 shown in FIG. 1 is in contact with the light entering surface 11A of the optical member 11, but in this case, the refractive index of the binder resin 14 may be different from the refractive index of the optical member 11. preferable. Specifically, the absolute value of the difference in refractive index between the binder resin 14 and the optical member 11 may be 0.1 or more and 0.2 or less. The refractive index of the binder resin 14 may be larger than the refractive index of the optical member 11 if it is different from the refractive index of the optical member 11, but if it is smaller than the refractive index of the optical member 11, light leakage may occur. It is preferable that the refractive index of the binder resin 14 is smaller than the refractive index of the optical member 11 because the amount of light emitted to the observer side increases.

Since quantum dots emit light isotropically, light is emitted in various directions. Here, when the refractive index of the binder resin is the same as the refractive index of the optical member, the light whose wavelength is converted by the quantum dots 15 and which is directed toward the light emitting surface 11B is the light wavelength as shown in FIG. 3 (A). Since it is not refracted at the interface between the conversion layer 12 and the optical member 13, if the incident angle with respect to the light emitting surface 11B is smaller than the critical angle, the light may be emitted from the light emitting surface 11B of the optical member 11 and become leaked light. .. On the other hand, when the refractive index of the binder resin 14 is smaller than the refractive index of the optical member 11, the light whose wavelength is converted by the quantum dots 15 and which is oblique in the direction toward the light emitting surface 11B is shown in FIG. 3 (B). As shown in the above, since refraction occurs at the interface between the light wavelength conversion layer 12 and the optical member 11, the incident angle with respect to the light emitting surface 11B becomes large, and the light can be totally reflected by the light emitting surface 11B, thereby reducing leakage light. Can be done. On the other hand, when the refractive index of the binder resin 14 is larger than the refractive index of the optical member 11, the oblique light that is wavelength-converted by the quantum dots 15 and is directed toward the light emitting surface 11B is shown in FIG. 3C. When the incident angle is larger than the critical angle, the light is reflected at the interface between the light wavelength conversion layer 12 and the optical member 11 to become light in the direction toward the light source side, and is reflected by the reflection member of the light source or the like. It can be incident on the optical member 11 via the light wavelength conversion layer 12.

Regarding the refractive index of the binder resin 14, for example, 10 pieces of the binder resin 14 are taken out from the light wavelength conversion layer 12 by cutting out or the like, and the refractive index of the binder resin 14 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 14. In the Becke method, a refractive index standard solution having a known refractive index is used, the above-mentioned fragments are placed on a slide glass or the like, the refractive index standard solution is dropped onto the sample, and the fragments are immersed in the refractive index standard solution. Is observed by microscopic observation, and the bright lines (Becke lines) generated on the surface of the binder resin and the light-scattering particles cannot be visually observed due to the difference in the refractive index between the surface of the binder resin and the light-scattering particles and the refractive index of the standard liquid. Refractive index This is a method in which the refractive index of the standard solution is a binder resin. The refractive index of the optical member 11 can also be obtained by the same method as that of the binder resin 14.

<< Light wavelength conversion particles >>
As shown in FIG. 2, the light wavelength conversion particle 13 is one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen (hereinafter, this element is referred to as a “specific element”) and a carboxylic acid. A resin particle 16 containing at least one of the above, and one or more quantum dots 15 contained in the resin particle 16 are included. The light wavelength conversion particles 13 shown in FIG. 2 further include a coating layer 17 that covers the surface of the resin particles 16. The light wavelength conversion particle 13 does not have to include the coating layer 17 as long as it includes the quantum dots 15 and the resin particles 16.

In the light wavelength conversion particles 13, the content of a specific element in the light wavelength conversion particles 13 measured by fluorescent X-ray analysis (XRF) 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 dot 15 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 content of the specific element shall be the average value of the values obtained by measuring three times. The lower limit of the content of the specific element in the light wavelength conversion particle 13 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. When the content of the specific element is 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 13 is preferably twice or more the average particle size of the quantum dots 15. When the average particle size of the light wavelength conversion particles 13 is twice or more the average particle size of the quantum dots 15, the distance from the quantum dots 15 to the surface of the light wavelength conversion particles 1 can be sufficiently secured, so that moisture and moisture and the like can be secured. Deterioration of the quantum dots 15 due to oxygen can be further suppressed. The average particle size of the light wavelength conversion particles 13 is obtained by measuring the particle size of 20 light wavelength conversion particles in the observation of the light wavelength conversion particles with a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), and averaging the particle diameters of the 20 light wavelength conversion particles. It can be obtained by calculating the value. The average particle size of the quantum dots 15 is obtained 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. be able to.

The average particle size of the light wavelength conversion particles 13 is preferably 10 nm or more and 100 μm or less. If the average particle size of the light wavelength conversion particles is 10 nm or more, the deterioration of the quantum dots can be further suppressed, and if it is 100 μm or less, there is no deterioration in dispersibility or defects in processing the light wavelength conversion member. .. The lower limit of the average particle size of the light wavelength conversion particles 13 is preferably 20 nm or more, and the upper limit of the average particle size of the light wavelength conversion particles 13 is preferably 30 μm or less, and more preferably 10 μm or less.

The shape of the light wavelength conversion particle 13 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 particle 1 is not spherical, the particle diameter of the light wavelength conversion particle 13 can be a true spherical value having the same volume.

It is preferable that each of the optical wavelength conversion particles 13 contains one or more quantum dots 15. If the number of quantum dots contained in one light wavelength conversion particle is one or more, the brightness does not decrease. 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 13 contains two or more quantum dots 15, and the average distance between the quantum dots 15 in the quantum dots 15 included in one light wavelength conversion particle 13 is 1 nm or more. Is preferable. If the average distance between the quantum dots is 1 nm or more, there is no possibility that the luminous efficiency will be lowered due to the concentration quenching that causes quenching due to the energy transfer between the quantum dots. The average distance between the quantum dots was obtained by randomly photographing the cross sections of 20 light wavelength conversion 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. The upper limit of the average distance between the quantum dots 15 is more preferably 100 nm or less.

<Quantum dot>
The quantum dots 15 are nano-sized semiconductor particles having a quantum confinement effect. The particle size and average particle size of the quantum dots 15 are, for example, 1 nm or more and 20 nm or less. When the quantum dot 15 absorbs light from an excitation source and reaches an energy excited state, the quantum dot 15 emits energy corresponding to the energy band gap of the quantum dot 15. Therefore, by adjusting the particle size or the composition of the substance of the quantum dots 15, the energy band gap can be adjusted, and energy in various levels of wavelength bands can be obtained. In particular, the quantum dots 15 can generate strong fluorescence in a narrow wavelength band.

Specifically, the energy band gap of the quantum dots 15 increases as the particle size decreases. That is, as the crystal size becomes smaller, the emission of the quantum dots 15 shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle size of the quantum dot 15, 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 a quantum dot is composed of CdSe / ZnS described later, blue light is emitted when the particle size of the quantum dot is 2.0 nm or more and 4.0 nm or less, and the particle size of the quantum dot is 3.0 nm. When the particle size is 6.0 nm or less, green light is emitted, and when the particle size of the quantum dots 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. Further, the light intensity of each of the above lights can be measured using a spectral radiance meter (for example, product name "CS2000", manufactured by Konica Minolta Co., Ltd.). 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.

As the quantum dots 15, one type of quantum dots may be used, but it is also possible to use two or more types of quantum dots each having an emission band in a single wavelength range due to different particle diameters or materials. is there. For example, when a light source that emits blue light is used, quantum dots that convert blue light into green light and quantum dots that convert blue light into red light may be used, or a light source that emits ultraviolet light is used. In this case, quantum dots that convert ultraviolet light to blue light, quantum dots that convert ultraviolet light to green light, and quantum dots that convert ultraviolet light to red light may be used. The quantum dot 15 shown in FIG. 2 includes a first quantum dot 15A and a second quantum dot 15B having an emission band in a wavelength range different from that of the first quantum dot 15A.

The quantum dots 15 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 15 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, or 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) composed 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 thiol, phosphorus compounds such as phosphine compounds or phosphine oxides, nitrogen compounds such as amines, and carboxyl group-containing compounds.

The shape of the quantum dot is not particularly limited, and may be, for example, spherical, rod-shaped, disk-shaped, or other shape. When the shape of the quantum dot is not spherical, the particle diameter of the quantum dot 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 can be obtained by a transmission electron microscope or a scanning transmission electron microscope. Further, since the emission color of the quantum dot changes depending on the particle diameter, it is also possible to obtain the particle diameter of the quantum dot by confirming the emission color of the quantum dot. Further, the crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, information on the particle size of quantum dots and the like can be obtained from the ultraviolet-visible (UV-Vis) absorption spectrum.

<Resin particles>
The resin particles 16 contain at least one of a specific element and a carboxylic acid. The resin particles 16 may contain two or more specific elements, or may contain both a specific element and a carboxylic acid. The specific element or carboxylic acid does not have to be fixed in the resin particles 16, but from the viewpoint of preventing the elution of the specific element or carboxylic acid, it is formed in the resin particles 16 by bonding with the resin constituting the resin particles 16. It is preferably fixed. When at least one of a specific element and a carboxylic acid is fixed to the resin constituting the resin particles 16, a compound containing the specific element (hereinafter, this compound is referred to as a “specific compound”) and the carboxylic acid. It is preferable that at least one of them 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 16 contains a hydroxyl group, and the specific compound and the carboxylic acid When at least one of the above contains a hydroxyl group as a polymerizable functional group, the polymerizable compound used for forming the resin constituting the resin particles 16 preferably contains an isocyanate group. When at least one of the specific compound and the carboxylic acid contains a polymerizable functional group, it is possible to polymerize with the polymerizable compound and fix at least one of the specific element and the carboxylic acid in the resin particles 16. When at least one of the specific compound and the carboxylic acid contains a polymerizable functional group, at least one of the specific compound and the carboxylic acid may contain one or more polymerizable functional groups, but may contain two or more. Good.

Whether or not the resin particles 16 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 shell of the quantum dot. 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 spectroscopy (IR), it can be determined that the resin particles contain a specific element or carboxylic acid.

The resin particles 16 are particles of a cured product of a mixture containing at least one of a specific element and a carboxylic acid and a polymerizable compound. The specific element is one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, but when incorporating a specific element, it is preferable to use a specific compound. Specific compounds include, for example, sulfur-based compounds, phosphorus-based compounds, nitrogen-based compounds, or mixtures thereof.

(Sulfur compound)
Sulfur-based compounds are compounds containing sulfur. The sulfur-based 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 and the polymerizable compound, the thiol compound can be fixed in the resin particles. In the present embodiment, the thiol compound and the polymerizable compound are separate compounds, but a thiol compound having a thiol group and a radically polymerizable functional group in one molecule may be used. When a thiol compound is used, it is particularly preferable to use a secondary thiol compound or a tertiary thiol compound from the viewpoint of pot life at the time of coating and suppression of odor.

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 secondary thiol compound and the tertiary thiol compound may have one or more thiol groups in one molecule, but are 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 secondary thiol compound or tertiary thiol compound is not particularly limited, but is represented by the following general formula (1) from the viewpoint of improving the curability when forming the optical wavelength conversion layer and the heat resistance and moist heat resistance of the quantum dots. Compounds are preferred.

In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms which may be ^{substituted, R 2} is an alkylene group having 1 to 10 carbon atoms which may be substituted, and R ³ is a carbon atom. It is an n-valent aliphatic group having 1 to 15 carbon atoms which may contain atoms other than the above, 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 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 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 compound)
Phosphorus-based compounds are compounds containing phosphorus. The phosphorus-based compound is not particularly limited, and examples thereof include a phosphonic acid-based compound, a phosphinic acid-based compound, a phosphine oxide-based compound, a phosphonic acid-based compound, a phosphinic acid-based compound, and a phosphine-based 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, a hydroxyl group, and 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, 2-Metachlorooxyethyl acid phosphate, Acid phosphoxyethyl methacrylate, Examples thereof include dibutyl phosphate, dimethyl vinyl phosphate, di-2-ethylhexylhydrozen phosphite, and dioleyl hydrozen phosphite.

(Nitrogen compound)
The nitrogen-based compound is a compound containing nitrogen. The nitrogen-based 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-buteneic 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 16 and facilitating the presence of the carboxylic acid around the quantum dots. Ethyl succinic acid is preferred.

(Polymerizable compound)
The polymerizable compound (curable compound) is a polymerizable compound, and examples thereof include an ionizing radiation polymerizable compound (ionizing radiation curable compound) and a thermosetting compound (thermosetting compound). 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.

The ionizing radiation polymerizable compound has at least one ionizing radiation polymerizable functional group in the molecule. Examples of the ionizing radiation polymerizable functional group include ethylenically unsaturated groups such as (meth) acryloyl group, vinyl group and allyl group. The "(meth) acryloyl group" means that both "acryloyl group" and "methacryloyl group" are included.

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

Examples of the ionizing radiation polymerizable monomer include 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 (Meta) acrylic acid esters such as, etc. can be mentioned.

As the ionizing radiation polymerizable oligomer, a polyfunctional oligomer having two or more functional groups is preferable, and a polyfunctional oligomer having three or more (trifunctional) ionizing radiation polymerizable functional groups 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 ionizing radiation polymerizable 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 an ionizing radiation-polymerizable prepolymer having a weight average molecular weight of more than 80,000 is used, it is preferable to mix and use the above-mentioned polymerizable monomer and the above-mentioned polymerizable oligomer. Examples of the polyfunctional polymerizable prepolymer include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

The thermopolymerizable compound has at least one thermopolymerizable functional group in the molecule. Examples of the thermopolymerizable functional group include a cyclic ether group such as an epoxy group and an oxetanyl group, a vinyl ether group and the like.

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, novolak phenol 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, 3,4-epoxycyclohexylmethylmethacrylate and the like. Examples thereof include an alicyclic epoxy compound containing one or more epoxy groups and one or more ester groups in the molecule.

<Coating layer>
The coating layer 17 covers the surface of the resin particles 16. The coating layer 17 is preferably a coat layer because it can easily cover the entire surface of the resin particles 3. The function of the coating layer 4 is not particularly limited, but for example, the coating layer 17 has a function of maintaining the shape of the resin particles, a function of preventing the components in the resin particles from being eluted from the particles, and a dispersion liquid or composition in the resin particles. At least one of the permeation prevention function of the components inside, the barrier property imparting function to oxygen and water vapor, the antireflection function of the excitation light incident on the resin particles, and the resin particle dispersibility imparting function when prepared as a dispersion liquid or composition. Has a function.

The film thickness of the coating layer 17 depends on the function exhibited by the coating layer 17, 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 resin particles. More preferably 1000 nm or less. In particular, when the coating layer 17 exerts a barrier property-imparting function, the film thickness of the coating layer 17 is 50 nm or more and 1000 nm or less from the viewpoint of preventing cracks in the coating layer while maintaining the barrier property. preferable. Further, when the coating layer 17 exhibits an antireflection function and the refractive index satisfies the relationship of binder resin <coating layer <resin particle relationship or binder resin> coating layer> resin particles, which will be described later, the light wavelength conversion particles. It is more preferable that the thickness of the coating layer 17 is 50 nm or more and 300 nm or less from the viewpoint of suppressing reflection on the surface of the 13 and efficiently incorporating the excitation light into the resin particles 16. The film thickness of the coating layer 17 is determined by photographing a cross section of the light wavelength conversion particle 13 using a scanning electron microscope (SEM) and measuring the film thickness of the light wavelength conversion particle 13 at 20 points in the image of the cross section. The average value of the film thickness at 20 points.

Although it depends on the function of the coating layer 17, when the coating layer 17 has a function of retaining the shape of the resin particles, the coating layer 17 may be formed by using, for example, a composition for a coating layer containing a polymerizable compound. It is possible. Since the polymerizable compound is the same as the polymerizable compound used for forming the resin particles 16, the description thereof will be omitted here. Among these, from the viewpoint of improving the adhesion between the resin particles and the coating layer, for example, when the resin particles are formed from an ionizing radiation-polymerizable compound, they are formed by using a coating layer composition containing an ionizing radiation-polymerizable compound. It is preferable that the resin particles are formed of a thermopolymerizable compound by using a coating layer composition containing the thermopolymerizable compound.

When a barrier layer that suppresses the permeation of water and oxygen is formed as the coating layer 17, examples of the constituent material of the barrier layer include inorganic oxides. Specifically, examples of the inorganic oxide 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 is selected from the viewpoint of low permeability of oxygen and water vapor. 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.

The barrier layer is preferably surface-modified with a silane coupling agent from the viewpoint of improving the adhesion with the binder resin 14. The silane coupling agent includes a vinyl group, an epoxy group, a styryl group, a methacryl group, an acrylic group, an amino group, a ureido group, a mercapto group, and a sulfide group, although it depends on the type of the polymerizable compound that becomes the binder resin 14 after curing. And those having one or more reactive functional groups selected from the group consisting of isocyanate groups can be used. When a compound having a (meth) acryloyl group is used as the polymerizable compound, the coupling agent is at least one reactive material selected from the group consisting of a mercapto group, a (meth) acryloyl group, a vinyl group and a styryl group. It preferably has a functional group. When a compound having at least one group selected from the group consisting of an epoxy group, an isocyanate group and a hydroxyl group is used as the polymerizable compound, the silane coupling agent is an epoxy group, an isocyanate group, a mercapto group and an amino. It preferably has at least one reactive functional group selected from the group consisting of groups.

When the surface of the light wavelength conversion particles is the surface of the resin particles, the light wavelength conversion particles tend to aggregate in the composition for the light wavelength conversion layer, so that the dispersibility may be inferior. However, the surface of the light wavelength conversion particles is a barrier. In the case of the surface of the layer, the light wavelength conversion particles are less likely to aggregate in the composition for the light wavelength conversion layer, so that the dispersibility can be improved.

The light wavelength conversion particle 13 can be produced, for example, by the following method. First, a composition for light wavelength conversion particles containing quantum dots, at least one of the above-mentioned specific compound and carboxylic acid, and the above-mentioned polymerizable compound is 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. As a result, it is possible to obtain light wavelength conversion particles whose surface is the surface of the resin particles. The composition for light wavelength conversion particles preferably contains a polymerization initiator. The light wavelength conversion particles provided with the coating layer can be obtained by forming the coating layer on the surface of the resin particles.

The light wavelength conversion particles 13 can also be produced by the following methods. First, a composition for light wavelength conversion particles containing quantum dots, at least one of the above-mentioned specific compound and carboxylic acid, and the above-mentioned polymerizable compound is granularly dispersed in a poor solvent such as water. 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, and the surface is made of resin particles. Light wavelength conversion particles on the surface can be obtained. 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. Also in this case, the light wavelength conversion particles provided with the coating layer can be obtained by forming the coating layer on the surface of the resin particles in the same manner as described above.

When a barrier layer is formed as a coating layer on the surface of the resin particles, the barrier layer can be prepared by using a sol-gel method. Specifically, first, an appropriate amount of a metal alkoxide (1) such as tetraethoxysilane is added to the resin particles and hydrolyzed appropriately to hydrolyze the surface of the resin particles with the metal alkoxide (1). Replace with a thing. 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 resin particles covered with the metal alkoxide (1). The resin particles settle in the aqueous phase. Since the metal alkoxide (2) near the surface is hydrolyzed at a slower rate than the metal alkoxide (1), the alkoxide on the surface of the resin particles is dehydrated and condensed at once when precipitated in the aqueous phase to form a large lump. prevent. An inorganic oxide layer such as a silica glass layer is further deposited on the resin particles 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 the core resin particles by the usual Stöber process. Thereby, the barrier layer can be formed.

<< Binder resin >>
The binder resin 14 is not particularly limited, and examples thereof include a cured product (polymer, crosslinked product) of a polymerizable compound. Since the polymerizable compound is the same as the polymerizable compound described in the column of resin particles, the description thereof will be omitted here.

<< Light-scattering particles >>
Light-scattering particles are particles that have the effect of changing the traveling direction of light by scattering the light that has entered the light wavelength conversion layer.

The average particle size of the light-scattering particles is preferably 20 times or more and 2000 times or less, and more preferably 50 times or more and 1000 times or less the average particle size of the quantum dots. If the average particle size of the light-scattering particles is 20 times or more the average particle size of the quantum dots, sufficient light scattering performance can be obtained in the light wavelength conversion layer, and the average particle size of the light-scattering particles is the quantum dots. If it is 2000 times or less of the average particle size of, the number of light-scattering particles is larger when the addition amount is the same than when it is more than 2000 times, so that the number of scattering points is large and a sufficient light scattering effect is obtained. Can be obtained. 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 described above.

The average particle size of the light-scattering particles 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. When the average particle size of the light scattering particles is 1/300 or more of the average film thickness of the light wavelength conversion layer, sufficient light scattering performance can be obtained in the light wavelength conversion layer, and the average particle size of the light scattering particles. If is 1/20 or less of the average film thickness of the light wavelength conversion layer, the ratio of light scattering particles to the light wavelength conversion layer is larger when the addition amount is the same than when it exceeds 1/20. The number of scattering points is large, and a sufficient light scattering effect can be obtained.

Specifically, the average particle size of the light-scattering particles 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. When the average particle size of the light scattering particles is 0.1 μm or more, the light wavelength conversion efficiency of the light wavelength conversion member is sufficient. On the other hand, when the average particle size of the light-scattering particles is 10 μm or less, the number of light-scattering particles is larger when the addition amount (mass%) is the same than when the average particle size of the light-scattering particles exceeds 10 μm. Therefore, the number of scattering points is increased, and a sufficient light scattering effect can be obtained.

The shape of the light-scattering particles is not particularly limited, and for example, spherical (true spherical, substantially true spherical, elliptical spherical, etc.), polyhedral, rod-shaped (cylindrical, prismatic, etc.), flat plate-like, flaky, and indefinite shape. And so on. 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 are preferably surface-treated with a silane coupling agent from the viewpoint of firmly fixing the light-scattering particles in the binder resin. By surface-treating with a silane coupling agent, it can be chemically bonded to a binder resin described later.

The silane coupling agent is a group consisting 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 the polymerizable compound used. It is possible to use one having one or more reactive functional groups selected from. When a compound having a (meth) acryloyl group is used as the polymerizable compound, the coupling agent is at least one reactive material selected from the group consisting of a thiol group, a (meth) acryloyl group, a vinyl group and a styryl group. It preferably has a functional group. When a compound having at least one group selected from the group consisting of an epoxy group, an isocyanate group and a hydroxyl group is used as the polymerizable compound, the silane coupling agent is an epoxy group, an isocyanate group, a thiol group and an amino. It preferably has at least one reactive functional group selected from the group consisting of groups.

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 Inorganic particles are preferable because the incident light to the wavelength conversion layer can be suitably scattered and the light wavelength conversion efficiency with respect to the incident light can be preferably improved.

The 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, they are also preferable from the viewpoint of obtaining a large Mie scattering intensity. The light scattering particles may be made of two or more kinds of materials because the light wavelength conversion efficiency with respect to the incident light by the light wavelength conversion layer can be more preferably improved.

<<<< Other light wavelength conversion members >>>>>
In the light wavelength conversion member 10 shown in FIG. 1, the light wavelength conversion particle 13 is used, but as the light wavelength conversion member, a quantum dot is used instead of the light wavelength conversion particle 13 or together with the light wavelength conversion particle 13. It may be a light wavelength conversion member using a light wavelength conversion particle including a light wavelength conversion particle that wraps a quantum dot and suppresses the transmission of water and oxygen.

The light wavelength conversion member 20 shown in FIG. 4 includes an optical member 11 having an incoming light incident surface 11A and an outgoing light emitting surface 11B, and an optical wavelength conversion layer 21 provided on the light incoming surface 11A side of the optical member 11. .. Of the members shown in FIGS. 4 and subsequent drawings, those having the same reference numerals as the members shown in FIG. 1 are the same as the members shown in FIG. 1, and thus the description thereof will be omitted. It shall be.

<<< Light wavelength conversion layer >>>
As shown in FIG. 4, the light wavelength conversion layer 21 includes the light wavelength conversion particles 22 as the second light wavelength conversion particles and the binder resin 14. The light wavelength conversion layer 21 may contain light scattering particles in addition to the light wavelength conversion particles 22 and the binder resin 14.

<< Light wavelength conversion particles >>
The light wavelength conversion particle 22 is also a particle that converts the wavelength of incident light into another wavelength. As shown in FIG. 5, the light wavelength conversion particle 22 includes a light-transmitting barrier particle 23 that suppresses the transmission of water and oxygen, and a quantum dot 15 contained in the barrier particle 23. There is no air layer between the quantum dots 15 and the barrier particles 23, and the surface of the quantum dots 15 is in close contact with the barrier particles 23.

The light wavelength conversion particle 22 preferably contains 1 or more and 50 or less quantum dots 15 per particle, and preferably contains 1 or more and 40 or less quantum dots or 1 or more and 35 or less quantum dots 15 per particle. It is more preferable to be. If the number of quantum dots contained in one light wavelength conversion particle is less than one, the brightness may be lowered, and if the number of quantum dots contained in one light wavelength conversion particle exceeds 50, the quantum is quantum. Emission efficiency may decrease due to density extinction that causes quenching due to energy transfer between dots. The number of quantum dots contained in one light wavelength conversion particle is 100,000 times the cross section of 20 light wavelength conversion particles at random using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). It is obtained by taking a picture at a magnification of ~ 500,000 times, calculating the number of quantum dots contained in one light wavelength conversion particle from the obtained image of the cross section, and calculating the average value of the calculated number of quantum dots. be able to.

The average particle size of the light wavelength conversion particles 22 is preferably 10 nm or more and 500 nm or less. If the average particle size of the light wavelength conversion particles is 10 nm or more, sufficient barrier properties can be imparted to the quantum dots, and if it is 500 nm or less, the barrier properties of the barrier particles are not clear. There is no risk of instability. The average particle size of the light wavelength conversion particles is obtained by measuring the particle size of 20 light wavelength conversion particles in the cross-sectional observation of the light wavelength conversion sheet with a transmission electron microscope or a scanning transmission electron microscope, and calculating the average value thereof. Can be sought. The lower limit of the average particle size of the light wavelength conversion particles 22 is preferably 20 nm or more, and the upper limit of the average particle size of the light wavelength conversion particles 22 is preferably 200 nm or less, more preferably 100 nm or less.

<Barrier particles>
The barrier particles 23 wrap the quantum dots 15 and have a light-transmitting property and a barrier property that suppresses the permeation of water and oxygen. By wrapping the quantum dots 15 with the barrier particles 23, it is possible to prevent the quantum dots 15 from coming into contact with water or oxygen, so that it is possible to prevent the quantum dots 15 from being deteriorated by water or oxygen. As a result, it is possible to suppress a decrease in the luminous efficiency of the quantum dots 15 without providing a barrier layer. In the present specification, "light transmission" means having a property of transmitting light, and "light transmission" also includes transparency. In the present invention, since the quantum dots are surrounded by barrier particles, it can be said that the barrier particles have light transmittance if the light emission from the quantum dots emitted from the light wavelength conversion sheet can be confirmed. The emission of quantum dots can be confirmed using a fluorometer.

The material for forming the barrier particles 23 is not particularly limited as long as it has light transmittance and barrier properties, and examples thereof include inorganic oxides. Specifically, examples of the inorganic oxide 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 is selected from the viewpoint of low permeability of oxygen and water vapor. 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.

When the quantum dot 15 contains Cd, the thickness of the barrier particle 23 (distance from the surface of the quantum dot to the outer surface of the barrier particle) must be 2 nm or more in order to prevent the elution of Cd contained in the quantum dot 15. Is preferable, and 4 nm or more is more preferable. When the average particle diameter of the light wavelength conversion particles 13 is about 50 nm, the thickness of the barrier particles 23 can be 10 nm or more. Further, when the average particle diameter of the light wavelength conversion particles 13 is about 100 nm, the thickness of the barrier particles 23 can be 20 nm or more. The thickness of the barrier particles can be easily measured as an outer portion that does not contain quantum dots in transmission electron microscope observation. When the thickness differs depending on the position of the peripheral edge of the barrier particle, the thickness of the barrier particle is taken by averaging the entire peripheral edge of the barrier particle.

The barrier particles 23 are preferably chemically bonded to the binder resin 12 from the viewpoint of improving the adhesion to the binder resin 14. This chemical bond can be carried out by the barrier particles 23 surface-modified with a silane coupling agent.

The silane coupling agent may be a vinyl group, an epoxy group, a styryl group, a methacryl group, an acrylic group, an amino group, a ureido group, a mercapto group, a sulfide group and an isocyanate group, depending on the type of curable binder resin precursor used. It is possible to use one having one or more reactive functional groups selected from the group consisting of. When a compound having a (meth) acryloyl group is used as the curable binder resin precursor, the coupling agent is at least one selected from the group consisting of a mercapto group, a (meth) acryloyl group, a vinyl group and a styryl group. It is preferable to have a reactive functional group of. When a compound having at least one group selected from the group consisting of an epoxy group, an isocyanate group, and a hydroxyl group is used as the curable binder resin precursor, the silane coupling agent is an epoxy group, an isocyanate group, or a mercapto. It preferably has at least one reactive functional group selected from the group consisting of groups and amino groups.

As a method of surface-treating the barrier particles 23 with a silane coupling agent, a dry method of spraying the silane coupling agent on the barrier particles 23 or a method of dispersing the barrier particles 23 in a solvent and then adding the silane coupling agent to react. Wet method and the like can be mentioned.

The light wavelength conversion particles 22 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. As a result, the light wavelength conversion particles 22 can be obtained.

<<<< Other light wavelength conversion members >>>>>
In the light wavelength conversion member 10 shown in FIG. 1, the light wavelength conversion layer 12 is in contact with the light entry surface 11A of the optical member 11, but the light wavelength conversion member includes the light wavelength conversion layer and the light input of the optical member. The light wavelength conversion member may have a light wavelength conversion layer and a light transmission layer having a refractive index different from that of the optical member interposed between the surface.

The optical member 30 shown in FIG. 6 includes an optical member 11 having an incoming light incident surface 11A and an outgoing light emitting surface 11B, an optical wavelength conversion layer 21 provided on the light incoming surface 11A side of the optical member 11, and an optical wavelength conversion layer 12. It is provided with a light transmitting layer 31 provided between the optical member 11 and the light receiving surface 11A of the optical member 11.

<Light transmission layer>
The light transmitting layer 31 is a layer having light transmitting property. The light transmitting layer 31 has a refractive index different from the refractive index of the binder resin 14 and the refractive index of the optical member 11, and is in contact with the light wavelength conversion layer 12 and the light incoming surface 11A. The absolute value of the difference in refractive index between the light transmitting layer 31 and the binder resin 14 and the light transmitting layer 31 and the optical member 11 may be 0.1 or more and 0.2 or less, respectively. The refractive index of the light transmitting layer 31 may be larger than the refractive index of the binder resin 14 or the refractive index of the optical member 11 as long as it is different from the refractive index of the binder resin 14 or the refractive index of the optical member 11. When it is smaller than the refractive index of the resin 14 and the refractive index of the optical member 11, light leakage is reduced and the proportion of light emitted to the observer side is increased. Therefore, the refractive index of the light transmitting layer 31 is determined by the binder resin 14. It is preferable that the refractive index is smaller than the refractive index of the optical member 11 and the refractive index of the optical member 11. The refractive index of the light transmitting layer 31 can be obtained by the same method as that of the binder resin 14.

When the refractive index of the light transmitting layer is the same as the refractive index of the optical member, the light that is wavelength-converted by the quantum dots and is directed toward the light emitting surface side is not refracted at the interface between the light transmitting layer and the optical member, so that the light emitting surface is not refracted. If the incident angle with respect to the light is smaller than the critical angle, the light may be emitted from the light emitting surface of the optical member and become leaked light. On the other hand, when the refractive index of the light transmitting layer 31 is smaller than the refractive index of the optical member 11, as shown in FIG. 7A, the wavelength is converted by the quantum dots 15 and the light emitting surface is emitted. Diagonal light in the direction toward 11B is refracted at the interface between the light transmitting layer 31 and the optical member 11, and the incident angle with respect to the light emitting surface 11B becomes large. Can be reduced. On the other hand, when the refractive index of the light transmitting layer 31 is smaller than the refractive index of the binder resin 14, the light is wavelength-converted by the quantum dots 15 and is oblique light in the direction toward the light transmitting layer 31. Light whose incident angle is larger than the critical angle is reflected at the interface between the light wavelength conversion layer 12 and the light transmission layer 31 to become light in the direction toward the light source side, and is reflected by the reflection member of the light source to convert the light wavelength. It can be incident on the optical member 11 via the layer 12 and the light transmitting layer 31.

<<<< Other light wavelength conversion members >>>>>
In the light wavelength conversion member 10 shown in FIG. 1, an optical member 11 having a flat light emitting surface 11B is used, but the light wavelength conversion member is a light wavelength conversion member provided with an optical member having an uneven light emitting surface. It may be.

The light wavelength conversion member 40 shown in FIG. 8 includes an optical member 41 having an incoming light incident surface 41A and an outgoing light emitting surface 41B, and an optical wavelength conversion layer 12 provided on the light incoming surface 41A side of the optical member 41. .. Of the light emitting surface 41B of the optical member 41, a concave-convex shape is formed on the light entering surface 41 side.

The concave-convex shape is composed of a unit prism 42 having a triangular cross section of 1 or more, preferably 2 or more. The unit prism 42 is provided linearly in the direction along the light entering surface 41C. The height h of the unit prism 42 is constant. The width p of the unit prism gradually increases from the light entering surface 41A to the side surface 41C opposite to the light entering surface 41A.

When the refractive index of the light wavelength conversion member is the same as the refractive index of the optical member, the light emitted in the oblique direction, which is wavelength-converted by the quantum dots and toward the light emitting surface side, is not refracted at the interface between the light transmitting layer and the optical member. If the incident angle with respect to the surface is smaller than the critical angle, the light may be emitted from the light emitting surface of the optical member and become leaked light. On the other hand, in the optical member shown in FIG. 8, since the concave-convex shape is formed on the light-injecting surface 41 side of the light-emitting surface 41B of the optical member 41, the same angle is formed as shown in FIG. Since the incident angle with respect to the light emitting surface 41B is larger than that in the case where the light emitting surface is a flat surface, the light can be totally reflected by the uneven shape. Thereby, the leakage light can be reduced.

In FIG. 8, the width p of the unit prism gradually increases from the light entering surface 41A to the side surface 41C opposite to the light entering surface 41A, but as shown in FIG. 10, the width p of the unit prism 42. May be constant. Further, the depth d of the unit prism 42 may be changed as shown in FIG. 11 for the purpose of improving the total reflection condition of the light emitting surface 41A, and further, for the same purpose, FIG. 12 shows. As shown, the width p of the unit prism 42 is gradually widened from the incoming surface 41A to the side surface 41C opposite to the incoming surface 41A, and the height of the unit prism 42 is kept constant while maintaining the unit prism 42. The top may be a flat surface 42A. In this case, the unit prism 42 has a trapezoidal cross section. Further, a concave-convex shape may be formed on the back surface of the optical member 41 opposite to the light emitting surface 41B from the viewpoint of reducing leakage light.

<<< Manufacturing method of optical wavelength conversion member >>>
The light wavelength conversion member 10 can be manufactured, for example, as follows. First, as shown in FIG. 13 (A), a composition for an optical wavelength conversion layer containing the optical wavelength conversion particles 13 and a polymerizable compound that becomes a binder resin after curing is provided on the light incoming surface 11A of the optical member 11. It is coated with a coating device such as a dispenser (for example, product name "SHOT MINI 100S", manufactured by Musashi Engineering Co., Ltd.) and dried to form a coating film 18 of a composition for an optical wavelength conversion layer. The composition for the light wavelength conversion layer may contain light scattering particles, a polymerization initiator, a solvent and the like, in addition to the light wavelength conversion particles and the polymerizable compound.

The viscosity of the composition for the optical wavelength conversion layer is preferably 10 mPa · s or more and 10000 mPa · s or less. If the viscosity of the composition for the light wavelength conversion layer is less than 10 mPa · s, it may be difficult to form a sufficient film thickness, and if it exceeds 10000 mPa · s, the composition for the light wavelength conversion layer is used. When applying, it becomes difficult to apply, and the leveling property may deteriorate. The lower limit of the viscosity of the composition for the light wavelength conversion layer is preferably 10 mPa · s or more, and the upper limit of the viscosity of the composition for the light wavelength conversion layer is preferably 10000 mPa · s or less.

The content of the light wavelength conversion particles with respect to the total solid content mass of the composition for the light wavelength conversion layer is preferably 1% by mass or more and 40% by mass or less, and more preferably 3% by mass or more and 30% by mass or less. .. When the content of the light wavelength conversion particles is 1% by mass or more, sufficient emission intensity can be obtained, and when the content of the light wavelength conversion particles is 40% by mass or less, the processing at the time of film formation is easy. Become.

The content of the polymerizable compound with respect to the total solid content mass of the composition for the optical wavelength conversion layer is preferably 30% by mass or more, and preferably 50% by mass or more and 99% by mass or less. When the content of the polymerizable compound is 30% by mass or more, sufficient curability can be obtained when the composition for the optical wavelength conversion layer is cured. When the composition for the light wavelength conversion layer contains both an ionizing radiation polymerizable compound and a thermopolymerizable compound, the above content means the total content of the ionizing radiation polymerizable compound and the thermopolymerizable compound. It shall be.

<< Polymerization Initiator >>
A polymerization initiator is a component that is decomposed by light or heat to generate radicals or ionic species to initiate or proceed with the polymerization (crosslinking) of a polymerizable compound. Examples of the polymerization initiator include a photopolymerization initiator (for example, a photoradical polymerization initiator, a photocationic polymerization initiator, a photoanionic polymerization initiator) and a thermal polymerization initiator (for example, a thermal radical polymerization initiator and a thermal cationic polymerization initiator). , Thermal anion polymerization initiator), or a mixture thereof.

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.

Commercially available photoradical polymerization initiators include, for example, IRGACURE184, IRGACURE369, IRGACURE379, IRGACURE651, IRGACURE819, IRGACURE907, IRGACURE2959, IRGACURE OXE01, and Lucillin TPO (all manufactured by BASF Japan). Examples thereof include ADEKA), SPEEDCURE EMK (manufactured by Siebel Hegner Japan), benzoine methyl ether, benzoin ethyl ether, and benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.).

Examples of the photocationic polymerization initiator include aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts. Examples of commercially available photocationic polymerization initiators include ADEKA OPTMER SP-150 and ADEKA OPTMER SP-170 (both manufactured by ADEKA).

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.

Examples of the polymer azo initiator having a structure in which a plurality of units such as polyalkylene oxide are bonded via the azo group include a polycondensate of 4,4'-azobis (4-cyanopentanoic acid) and polyalkylene glycol. Examples thereof include a polycondensate of 4,4'-azobis (4-cyanopentanoic acid) and a polydimethylsiloxane having a terminal amino group.

Examples of the peroxide include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, peroxydicarbonates and the like.

Commercially available thermal radical polymerization initiators include, for example, Perbutyl O, Perhexyl O, Perbutyl PV (all manufactured by NOF CORPORATION), V-30, V-501, V-601, and VPE-0201. , VPE-0401, VPE-0601 (all manufactured by Wako Pure Chemical Industries, Ltd.) and the like.

Examples of the thermal cationic polymerization initiator include various onium salts such as a quaternary ammonium salt, a phosphonium salt, and a sulfonium salt. Commercially available thermal cation polymerization initiators include, for example, ADEKA OPTON CP-66, ADEKA OPTON CP-77 (all manufactured by ADEKA), Sun Aid SI-60L, Sun Aid SI-80L, and Sun Aid SI-100L (all of which are manufactured by ADEKA). All of them include Sanshin Kagaku Kogyo Co., Ltd.) and CI series (Nippon Soda Co., Ltd.).

The content of the polymerization initiator in the composition for the optical wavelength conversion layer 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 polymerizable compound. If the content of the polymerization initiator is 0.3 parts by mass or more, the polymerizable compound can be reliably cured, and if it is 5.0 parts by mass or less, the optical wavelength conversion layer turns yellow. There is no fear.

<< Solvent >>
The solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, propanol and isopropyl alcohol; ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene and cyclohexane.

After forming the coating film 18, the coating film is irradiated with ionizing radiation or heat is applied as shown in FIG. 13B to cure the polymerizable compound, and the light entering surface 11A of the optical member 11 is formed. The optical wavelength conversion layer 12 is formed on the surface. As a result, the light wavelength conversion member 10 shown in FIG. 1 is obtained.

It is considered that the reason why quantum dots are easily deteriorated 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. It is considered that this causes the quantum dots to deteriorate. On the other hand, in the present embodiment, in the light wavelength conversion layer 12, at least one of one or more elements and a carboxylic acid in which the resin particles 16 enclosing the quantum dots 15 are selected from the group consisting of sulfur, phosphorus, and nitrogen. Since the light wavelength conversion particles 13 containing the above are used, 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 15, thereby suppressing deterioration of the quantum dots 15. can do. This is such that at least one of the sulfur component, the phosphorus component, the nitrogen component and the carboxylic acid present in the resin particles 16 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 it binds to a quantum dot instead of a ligand and exerts at least one of a function of substituting for a ligand and a function of capturing oxygen). Further, since the light wavelength conversion layer 21 uses the light wavelength conversion particles 22 including the barrier particles 23 that enclose the quantum dots 15, the barrier particles 23 can protect the quantum dots 15 from water and oxygen. Deterioration of the quantum dot 15 can be suppressed. In either case, since the deterioration of the quantum dots 15 can be suppressed, it is not necessary to enclose the light wavelength conversion particles 13 and 22 in a container such as a glass tube in the on-edge method. As a result, the problem of cracking in the glass tube does not occur, so that the yield can be improved. Further, since the light wavelength conversion layers 12 and 23 may be simply provided on the light entering surface 11A side of the optical member 11, the structure can be simplified.

As described above, in the present embodiment, the resin particles 16 that enclose the quantum dots 15 contain at least one of one or more elements and a carboxylic acid selected from the group consisting of sulfur, phosphorus, and nitrogen. Deterioration of the quantum dots 15 can be suppressed as compared with resin particles that do not contain elements or carboxylic acids, but in the quantum dots, a part of the surface of the quantum dots is exposed on the surface of the resin particles. Some are. When the coating layer 17 is a barrier layer that suppresses the permeation of water and oxygen, the resin particles 16 are formed by the barrier layer even when a part of the quantum dots 15 is exposed on the surface of the resin particles 16. Since the contact between the quantum dots 15 which are partially exposed from the water and oxygen can be suppressed, the deterioration of the quantum dots 15 can be further suppressed.

The light wavelength conversion members 10, 20, 30, and 40 can be used by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion member 10 is incorporated into a backlight device and an image display device will be described. The light wavelength conversion members 20, 30, and 40 can also be incorporated into the same backlight device and image display device as described below. FIG. 14 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, and FIG. 15 is a perspective view of the lens sheet shown in FIG.

<<< Image display device >>>
The image display device 50 shown in FIG. 14 includes a backlight device 60 and a display panel 90 arranged on the light emitting side of the backlight device 60. The image display device 50 has a display surface 50A for displaying an image. In the image display device 50 shown in FIG. 14, the surface of the display panel 90 is the display surface 50A.

The backlight device 60 illuminates the display panel 90 from the back side in a plane shape. The display panel 90 functions as a shutter that controls the transmission or blocking of light from the backlight device 60 for each pixel, and is configured to display an image on the display surface 60A.

<< Display panel >>
The display panel 90 shown in FIG. 14 is a liquid crystal display panel, and is between the polarizing plate 91 arranged on the incoming light side, the polarizing plate 92 arranged on the light emitting side, and the polarizing plate 91 and the polarizing plate 92. It includes an arranged liquid crystal cell 93. The polarizing plates 91 and 92 decompose the incident light into two orthogonal linearly polarized light components (S-polarized light and P-polarized light) and vibrate in one direction (direction parallel to the transmission axis) (for example, P). It has a function of transmitting polarized light) and absorbing a linearly polarized light component (for example, S-polarized light) that vibrates in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

<< Backlight device >>
The backlight device 60 shown in FIG. 14 is configured as an edge light type backlight device, and has a light source 65, an optical wavelength conversion member 10 arranged on the side of the light source 65, and an emission side of the light wavelength conversion member 10. The lens sheet 70 arranged in the lens sheet 70, the lens sheet 75 arranged on the light source side of the lens sheet 70, the reflective polarization separation sheet 80 arranged on the light source side of the lens sheet 75, and the back surface 11C of the optical member 11. It is provided with a reflective sheet 85. The backlight device 60 includes lens sheets 70 and 75, a reflective polarizing separation sheet 80, and a reflective sheet 85, 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 device 60 has a light emitting surface 60A that emits light in a planar manner. In the backlight device 60 shown in FIG. 14, the light emitting surface of the reflective polarizing separation sheet 80 is the light emitting surface 60A of the backlight device 60.

The light wavelength conversion member 10 is arranged so that the light wavelength conversion layer 12 side is the light source 65 side and the light emitting surface 11A side of the optical member 11 is the lens sheet 70 side.

<Light source>
The light source 65 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 65 is composed of a large number of point-shaped light emitters arranged linearly along the light wavelength conversion member 10, specifically, a large number of light emitting diodes (LEDs). ..

Since the light wavelength conversion member 10 is arranged in the backlight device 60, the light source 65 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.

<Lens sheet>
The lens sheets 70 and 75 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, the light having a large incident angle is reflected by changing the traveling direction of the light having a large incident angle and emitting the light from the light emitting side to intensively improve the brightness in the front direction (condensing function) and reflecting the light having a small incident angle. It has a function of returning the light to the optical member 11 side (specular reflection function). The lens sheets 70 and 75 include a light transmitting base material 71 and a lens layer 72 provided on one surface of the light transmitting base material 71.

(Light transmissive base material)
Examples of the constituent material of the light-transmitting base material 71 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulphon, polysulphon, and polypropylene. , Polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, polymethylmethacrylate, polycarbonate, polyurethane, or thermoplastic resins such as cycloolefin polymer (COP). As the constituent material of the light transmissive base material 71, polyester (for example, polyethylene terephthalate, polyethylene naphthalate) is preferable.

The light-transmitting base material 71 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 material, or may be composed of a plurality of layers composed of layers of different types of constituent materials, depending on the intended use. Good.

(Lens layer)
As shown in FIG. 15, the lens layer 72 includes a sheet-shaped main body 73 and a plurality of unit lenses 74 arranged side by side on the light emitting side of the main body 73.

The main body 73 functions as a sheet-like member that supports the unit lens 74. As shown in FIG. 15, unit lenses 74 are arranged on the main body 73 without leaving a gap.

As shown in FIG. 15, the unit lens 74 extends linearly in a direction intersecting the arrangement direction AD of the unit lens 74, particularly linearly in the present embodiment. Further, in the present embodiment, a large number of unit lenses 74 included in one lens sheet 70, 75 extend in parallel with each other. Further, the longitudinal LD of the unit lenses 74 of the lens sheets 70 and 75 is orthogonal to the arrangement direction AD of the unit lenses 74 of the lens sheets 70 and 75.

The unit lens 74 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. In the present embodiment, as a unit lens, a triangular columnar unit prism whose width becomes narrower toward the light emitting side will be described. The shape of the cross section (also called the main cut surface of the lens sheet) parallel to both the normal direction of the sheet surfaces of the lens sheets 70 and 75 and the arrangement direction AD of the unit lens 104 is a triangular shape protruding toward the light emitting side. There is. In particular, from the viewpoint of intensively improving the brightness in the front direction, the cross-sectional shape of the unit lens 74 on the main cutting surface is an isosceles triangle shape, and the apex angle located between the equilateral sides protrudes to the light emitting side. , Each unit lens 74 is configured.

From the viewpoint of improving the efficiency of light utilization, the unit lens 74 preferably has an apex angle of 80 ° or more and 100 ° or less, and more preferably about 90 °. However, the tip of the unit lens 74 may be a curved surface in consideration of damage to the tip of the unit lens when the lens sheet is wound.

The dimensions of the lens sheets 70 and 75 can be set as follows, for example. First, as a specific example of the unit lens 74, the arrangement pitch of the unit lens 74 (corresponding to the width of the unit lens 74 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 74 has been rapidly improved in definition, and it is preferable that the arrangement pitch of the unit lens 74 is 10 μm or more and 50 μm or less. Further, the protruding height of the unit lens 74 from the main body 73 along the normal direction of the lens sheets 70 and 75 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 74 can be set to 60 ° or more and 120 ° or less.

As can be understood from FIG. 14, the arrangement direction of the unit lens 74 of the lens sheet 70 and the arrangement direction of the unit lens 74 of the lens sheet 75 intersect, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 80 transmits only the first linearly polarized light component (for example, P-polarized light) among the light emitted from the lens sheet 75, 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 80 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 80 again. Therefore, the reflective polarization separation sheet 80 transmits the first linearly polarized light component of the light incident again, and the second linearly polarized light component orthogonal to the first linearly polarized light component is reflected again. By repeating such a process, about 70 to 80% of the light emitted from the lens sheet 75 is emitted as the light source light which is the first linearly polarized light component. Therefore, further improvement in light utilization efficiency can be expected.

As the reflective polarizing separation sheet 80, "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 80.

<Reflective sheet>
The reflection sheet 85 has a function of reflecting the light leaked from the back surface 11C of the light wavelength conversion member 10 and causing it to enter the optical member 11 again. The reflective sheet 85 is composed of a white diffuse reflective sheet, a sheet made of a material having a high reflectance such as metal, a sheet containing a thin film made of a material having a high reflectance (for example, a metal thin film) as a surface layer, and the like. obtain. The reflection on the reflective sheet 85 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflective sheet 85 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

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

<Manufacturing 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 tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Co., Ltd.), tetraethylene glycol bis (3-mercaptopropionate) (Product name "EGMP-4", manufactured by SC Organic Chemical Co., Ltd.) 50 parts by mass, green luminescent 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 solvent, 10 parts by mass of polyvinyl alcohol, which is a dispersant, dissolved in 900 parts by mass of ion-exchanged water was added. Then, the composition 1 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 1 for light wavelength conversion particles and the poor solvent is raised to 50 ° C., and the temperature of the reaction solution is 50 ° C. Suspension polymerization was carried out in this state for 3 hours, and then the temperature of the reaction solution was raised to 80 ° C. in order to completely inactivate the thermal radical initiator, and the temperature of the reaction solution was 80 ° C. Stirring for 3 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. Then, the reaction solution was suction-filtered, and the filtration residue was washed with ion-exchanged water and then deliquesed to obtain light wavelength-converted particles 1. In the light wavelength conversion particle 1, 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 1 was 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 12 were also determined to be the same as those of the light wavelength conversion particles 1.

(Light wavelength conversion particle 2)
A silica glass layer as a barrier layer was formed on the surface of the resin particles of the light wavelength conversion particles 1 to obtain light wavelength conversion particles 2. The barrier layer was formed as follows. First, the surface of the light wavelength conversion particles 1 was covered with dodecylamine and then mixed with toluene (0.4 mL). Next, tetraethoxysilane (TEOS, 10 μL) was added to this mixture, and the mixture was stirred for 3 hours to prepare an organic mixture 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 mixture 1 and the aqueous solution 2 were mixed and stirred for 3 hours, the resin particles precipitated in the aqueous phase. The resin particles were taken out by centrifugation. Finally, 0.5 mL of the aqueous solution containing the above resin particles 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, the light wavelength conversion particles 2 obtained by covering the surface of the resin particles of the light wavelength conversion particles 1 with a silica glass layer having a thickness of 50 nm were obtained. The average particle size of the light wavelength conversion particles 2 was 3.1 μm.

(Light wavelength conversion particle 3)
Instead of composition 1 for optical wavelength conversion particles, 90 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.) 10 parts by mass, green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particles Diameter 3.3 nm) 1.0 part by mass, red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 mass Except for the use of composition 2 for optical wavelength conversion particles consisting of 1 part by mass and 1 part by mass of thermal radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.). , The light wavelength conversion particles 3 were obtained by the same procedure as the light wavelength conversion particles 1. 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 μm.

(Light wavelength conversion particle 4)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 50 parts by mass of tert-butyl mercaptan, green emission 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 emission quantum dots (product name "CdSe / ZnS 610") , SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass, and thermal radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile) ), Tokyo Kasei Kogyo Co., Ltd.) Light wavelength conversion particles 4 were obtained by the same procedure as for light wavelength conversion particles 1 except that the composition 3 for light wavelength conversion particles consisting of 1 part by mass was used. 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 μm.

(Light wavelength conversion particle 5)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 2-metacloyloxyethyl acid phosphate (product name) "Light ester P-2M", manufactured by Kyoeisha Chemical Co., Ltd.) 50 parts by mass, green emission 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 emission quantum dots (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 Light wavelength except that the composition 4 for light wavelength conversion particles consisting of 1 part by mass of a thermal radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used. Light wavelength conversion particles 5 were obtained by the same procedure as for conversion particles 1. 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 μm.

(Light wavelength conversion particle 6)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), acid phosphoxyethyl methacrylate (product name "Hosmer") M ”, manufactured by Unichemical Co., Ltd.) 50 parts by mass, green emission quantum dots (product name“ CdSe / ZnS 530 ”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) 1. 0 parts by mass, red emission quantum dots (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 thermal radical polymerization started Agent (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) Except for the use of the composition 5 for light wavelength conversion particles consisting of 1 part by mass, the light wavelength conversion particles 1 and Light wavelength conversion particles 6 were obtained by the same procedure. In the light wavelength conversion particles 6, green light emitting quantum dots and red light emitting quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 6 was 3 μm.

(Light wavelength conversion particle 7)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), stearylamine (product name "Farmin 80", Kao) 50 parts by mass, green emission 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 emission Quantum dots (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 thermal radical polymerization initiator (2,2' -Azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) Light by the same procedure as for the light wavelength conversion particles 1 except that the composition 6 for light wavelength conversion particles consisting of 1 part by mass was used. Wavelength conversion particles 7 were obtained. 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 μm.

(Light wavelength conversion particle 8)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), distearylamine (product name "Farmin D86"), Kao) 50 parts by mass, green emission quantum dots (product name "CdSe / ZnS 530", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm) 1.0 parts by mass, red Emission quantum dots (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 thermal radical polymerization initiator (2,2) '-Azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) By the same procedure as for the light wavelength conversion particles 1 except that the composition 7 for light wavelength conversion particles consisting of 1 part by mass was used. Light wavelength conversion particles 8 were obtained. In the light wavelength conversion particles 8, green light emitting quantum dots and red light emitting quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 8 was 3 μm.

(Light wavelength conversion particle 9)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), ω-carboxy-polycaprolactone mono (meth) acrylate (Product name "M-5300", manufactured by Toa Synthetic Co., Ltd.) 50 parts by mass, green emission 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 emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass, Light radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) except that the composition 8 for light wavelength conversion particles consisting of 1 part by mass was used. Light wavelength conversion particles 9 were obtained by the same procedure as for wavelength conversion particles 1. In the light wavelength conversion particles 9, green light emitting quantum dots and red light emitting quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 9 was 3 μm.

(Light wavelength conversion particle 10)
Instead of composition 1 for optical wavelength conversion particles, 50 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 2-acryloyloxyethyl succinic acid (product name "" NK ester A-SA ", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 50 parts by mass, green emission 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 emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) 1.0 part by mass, Light radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) except that the composition 9 for light wavelength conversion particles consisting of 1 part by mass was used. Light wavelength conversion particles 10 were obtained by the same procedure as for wavelength conversion particles 1. In the light wavelength conversion particles 10, 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 10 was 3 μm.

(Light wavelength conversion particle 11)
First, 0.2 parts by mass of green emitting quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle diameter 3.3 nm) and 0.2 parts by mass. Red emission quantum dots (product name "CdSe / ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm) were 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. Then, 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, an aggregate composed of green emission quantum dots and red emission quantum dots was wrapped in silica glass to obtain light wavelength conversion particles 11 having an average particle diameter of 50 nm.

(Light wavelength conversion particle 12)
Instead of composition 1 for optical wavelength conversion particles, 100 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), green emission 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 emission quantum dots (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 thermal radical polymerization initiator (2,2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Kasei Kogyo Co., Ltd.) Light wavelength conversion particles 12 were obtained by the same procedure as for light wavelength conversion particles 1 except that the composition 10 for light wavelength conversion particles consisting of 1 part by mass was used. In the light wavelength conversion particles 12, 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 12 was 12 μm.

<Adjustment of composition for optical wavelength conversion layer>
Each component was blended so as to have the composition shown below to obtain a composition for an optical wavelength conversion layer.
(Composition for Light Wavelength Conversion Layer 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 for Light Wavelength Conversion Layer 2)
-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 "Irgacure (" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 3)
-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 "Irgacure (" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 4)
-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 "Irgacure" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 5)
-Light wavelength conversion particles 5:20 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 "Irgacure" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 6)
-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 "Irgacure (" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 7)
-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

(Composition for Light Wavelength Conversion Layer 8)
-Light wavelength conversion particles 8:20 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 for Light Wavelength Conversion Layer 9)
-Light wavelength conversion particles 9:20 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 for Light Wavelength Conversion Layer 10)
-Light wavelength conversion particles 10:20 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 for Light Wavelength Conversion Layer 11)
-Light wavelength conversion particles 11:20 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 "Irgacure" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

(Composition for Light Wavelength Conversion Layer 12)
-Green emission quantum dots (product name "CdSe / ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass-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 parts by mass, epoxy acrylate (product name "Unidic V-5500", DIC) (Manufactured): 100 parts by mass, radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan): 1 part by mass

(Composition for Light Wavelength Conversion Layer 13)
-Light wavelength conversion particles 12:20 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 "Irgacure" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

<Example 1>
The composition 1 for the light wavelength conversion layer was applied to the light entering surface of the light guide plate of the backlight device of Kindle Fire (registered trademark) HDX7 to form a coating film. Then, the present invention relates to Example 1 in which an ultraviolet ray is irradiated so that the integrated light amount becomes 500 mJ / cm ² to cure the coating film, and an optical wavelength conversion layer having a film thickness of 2 mm is formed on the light entering surface of the light guide plate. An optical wavelength conversion member was obtained.

<Examples 2 to 11 and Comparative Examples 1 and 2>
In Examples 2 to 11 and Comparative Examples 1 and 2, the same as in Example 1 except that the compositions for each optical wavelength conversion layer shown in Table 2 were used instead of the composition 1 for the optical wavelength conversion layer. Then, a light wavelength conversion member was manufactured.

<Confirmation of specific elements and carboxylic acids in resin 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 10 and 12. Specifically, for the optical wavelength conversion particles 1 to 8 and 12, an energy dispersive X-ray analyzer (product name "JEM-2800" ( ^{equipped with 100 mm 2} silicon drift detector (SDD)), manufactured by JEOL Ltd.) At any position on or inside the resin particles at a distance of 3 nm or more from the surface of the quantum dot shell under the conditions of an acceleration voltage of 100 kV and a measurement time of 30 seconds, the sulfur element, phosphorus element, and nitrogen element It was confirmed whether at least one of them was detected. For the light wavelength conversion particles 9, 10 and 12, an infrared microscope (product name "Nicolet iN10", manufactured by Thermo Fisher Scientific) was used to surface the resin particles 3 nm or more away from the surface of the quantum dot shell. Alternatively, it was confirmed whether or not carboxylic acid was detected at an arbitrary position inside. 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>
In the light wavelength conversion particles 1 to 8 and 12, the content of a specific element contained in the light wavelength conversion particles was measured using a fluorescent X-ray analyzer (product name "EDX-800HS", manufactured by Shimadzu Corporation). The content of the specific element was taken as the average value of the values obtained by measuring three times.

<Measurement of water vapor permeability and oxygen permeability>
The water vapor transmittance and the oxygen transmittance were measured in the light wavelength conversion members according to Examples 1 to 11 and Comparative Examples 1 and 2, respectively. The water vapor transmittance of the light wavelength conversion member is determined by using a water vapor transmittance measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON) in accordance with JIS K7129: 2008 at an arbitrary location of the light wavelength conversion member. The measurement was carried out under the conditions of 40 ° C. and 90% relative humidity. Further, the oxygen transmittance of the light wavelength conversion member is an oxygen gas transmission rate measuring device (product name "OX-TRAN 2/21", MOCON) in accordance with JIS K7126: 2006 at any position of the light wavelength conversion member. The measurement was carried out under the conditions of 23 ° C. and 90% relative 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>
In the light wavelength conversion members according to the above Examples and Comparative Examples, a heat resistance test was performed in which the light wavelength conversion member was left in an environment of 80 ° C. for 500 hours, and a heat resistance test for the brightness of the light wavelength conversion member before the heat resistance test was performed. Later, the maintenance rate of brightness was investigated. Specifically, first, we prepared a backlight device for Kindle Fire (registered trademark) HDX7. 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. Then, instead of the light guide plate of this backlight device, an optical wavelength conversion member before the heat resistance test was incorporated in the same place. The light wavelength conversion member was incorporated so that the light wavelength conversion layer was on the blue light emitting diode side.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion member is turned on, the light wavelength conversion layer of the light wavelength conversion member is irradiated with blue light, and the light emission of the backlight device is emitted through the light emitting surface of the light guide plate. The brightness of the light emitted from the surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface of the backlight device in the thickness direction of the backlight device. It was measured using a Minolta) under the condition of a measurement angle of 1 °.

Next, the light wavelength conversion member before the heat resistance test was removed from the backlight device, and the light wavelength conversion member was subjected to a heat resistance test in which the light wavelength conversion member was left in an environment of 80 ° C. for 500 hours. Then, the light wavelength conversion member 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, the light wavelength conversion layer of the light wavelength conversion member is irradiated with blue light from the light emitting surface of the backlight device (the surface of the second prism sheet) via the light emitting surface of the light guide plate. The brightness of the emitted light is measured at a position 400 mm away from the light emitting surface of the backlight device in the thickness direction of the backlight device, using a spectral emission brightness meter (product name "CS2000", manufactured by Konica Minolta), and a measurement angle 1 It was measured under the condition of °.

From these measured brightnesss, the retention 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

The results are shown in Tables 1 and 2 below.

The results will be described below. As can be seen from Table 2, in the light wavelength conversion members according to Examples 1 to 11, the light wavelength conversion particles 1 to 10 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid. Since the light wavelength conversion particles 11 in which the quantum dots are contained in the barrier particles are used, the resin particles themselves or the resin particles containing the light wavelength conversion members and the quantum dots according to Comparative Example 1 in which the barrier particles themselves are not used. However, the brightness retention rate after the heat resistance test was higher than that of the light wavelength conversion member according to Comparative Example 2 in which the resin particles did not contain any specific element or carboxylic acid.

In the light wavelength conversion particles 1 to 8, 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 12, the content of the specific element measured by fluorescent X-ray analysis was less than 0.5% by mass. In the light wavelength conversion particles 12, although the composition 10 for light wavelength conversion particles used for forming the light wavelength conversion particles 12 does not contain a specific element, the content of the specific element is high. It is considered that the reason why it is 0.478% by mass is that the quantum dots themselves contain a sulfur component.

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, 20, 30, 40 ... Light wavelength conversion members 11, 41 ... Optical members 11A, 41A ... Light input surfaces 11B, 41B ... Light emission surfaces 12, 21 ... Light wavelength conversion layers 13, 22 ... Light wavelength conversion particles 15 ... Quantum Dot 16 ... Resin particles 17 ... Coating layer 23 ... Barrier particles 50 ... Image display device 60 ... Backlight device 90 ... Display panel

Claims (9)

An optical member having an incoming surface and an outgoing surface,
A light wavelength conversion layer provided on the light receiving surface side of the optical member and containing light wavelength conversion particles and a binder resin is provided.
The light incoming surface of the optical member is a side surface located between the light emitting surface and the back surface opposite to the light emitting surface.
The light wavelength conversion layer is in contact with the light incoming surface of the optical member,
The light wavelength conversion particles include a light-transmitting resin particle containing at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and a carboxylic acid, and quantum dots contained in the resin particle. first optical wavelength converting particles containing, and an optically transparent barrier particles, der least one of the second optical wavelength conversion particle comprising a quantum dot encapsulated in the barrier particles is,
An optical wavelength conversion member in which the refractive index of the binder resin is smaller than the refractive index of the optical member. Before Symbol the light exit surface of the optical member has an uneven shape on the light incident side, the light wavelength conversion member according to claim 1. The light wavelength conversion member according to claim 1 or 2 , wherein the optical member is a light guide plate. The light wavelength conversion member according to any one of claims 1 to 3, wherein the first light wavelength conversion particle further includes a coating layer covering the surface of the resin particle. The light wavelength conversion member according to claim 4 , wherein the coating layer is a barrier layer that suppresses the permeation of water and oxygen. The light wavelength conversion member according to any one of claims 1 to 5, wherein the barrier particles are inorganic oxide 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 any one of claims 1 to 6, which satisfies at least one of the above. Light source and
The light wavelength conversion member according to any one of claims 1 to 7, which receives light from the light source, is provided.
A backlight device in which the light wavelength conversion layer is located closer to the light source than the optical member. The backlight device according to claim 8 and
An image display device including a display panel arranged on the light emitting side of the backlight device.

Images