JP6844294B2 - Light wavelength conversion particles, light wavelength conversion particle dispersion, light wavelength conversion composition, light wavelength conversion member, light wavelength conversion sheet, backlight device, image display device, and method for manufacturing light wavelength conversion particles. - Google Patents

Description

The present invention relates to a light wavelength conversion particle, a light wavelength conversion particle dispersion, a light wavelength conversion composition, a light wavelength conversion member, a light wavelength conversion sheet, a backlight device, an image display device, and a method for producing the light wavelength conversion particle.

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.

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

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

Japanese Unexamined Patent Publication No. 2015-11518

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

Further, in the light wavelength conversion member having a form other than the light wavelength conversion sheet, the light wavelength conversion member may be arranged at a position close to the light source or the light source. It has been demanded.

The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide a light wavelength conversion particle having excellent heat resistance and moisture heat resistance, a light wavelength conversion particle dispersion liquid containing such a light wavelength conversion particle, and a light wavelength conversion composition. Further, to provide a light wavelength conversion member, a light wavelength conversion sheet, and a backlight device provided with such a light wavelength conversion member and a light wavelength conversion sheet, and an image conversion device, which have excellent heat resistance and moisture heat resistance. With the goal. Furthermore, an object of the present invention is to provide a method for producing such light wavelength conversion particles.

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 light wavelength conversion particles having excellent heat resistance and moisture heat resistance can be obtained by encapsulating the particles in. The present invention has been completed based on such findings.

According to one aspect of the present invention, the light wavelength conversion particles, which are 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 one or more quantum dots encapsulated in the resin particles, and an optical wavelength conversion particle is provided.

In the light wavelength conversion particles, the content of the element in the light wavelength conversion particles measured by fluorescent X-ray analysis may be 0.5% by mass or more.

In the light wavelength conversion particles, the average particle size of the light wavelength conversion particles may be twice or more the average particle size of the quantum dots.

The light wavelength conversion particles may further include a coating layer that covers the surface of the resin particles.

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

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

According to another aspect of the present invention, there is provided a light wavelength conversion particle dispersion liquid containing the dispersion medium and the above-mentioned light wavelength conversion particles dispersed in the dispersion medium.

According to another aspect of the present invention, there is provided a light wavelength conversion composition containing the above-mentioned light wavelength conversion particles and a polymerizable compound.

According to another aspect of the present invention, there is provided a light wavelength conversion member including the above light wavelength conversion particles.

According to another aspect of the present invention, the optical wavelength conversion sheet is an optical wavelength conversion sheet including a binder resin and an optical wavelength conversion layer containing the above-mentioned optical wavelength conversion particles dispersed in the binder resin. Provided.

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

The light wavelength conversion sheet may be composed of only the light wavelength conversion layer.

The light wavelength conversion sheet may further include an overcoat layer made of a resin that covers at least one surface of the light wave conversion layer.

In the light wavelength conversion sheet, an optical member may be further provided on at least one surface side of the light wavelength conversion layer, and the light wavelength conversion layer and the optical member may be integrated without interposing an air layer.

The light wavelength conversion sheet may further include a barrier film provided on at least one surface of the light wavelength conversion layer and protecting the quantum dots from moisture and oxygen.

According to another aspect of the present invention, there is provided a backlight device including a light source and the light wavelength conversion member or the light wavelength conversion sheet that receives light from the light source.

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

According to another aspect of the present invention, the method for producing light wavelength conversion particles, which comprises a compound containing quantum dots and one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, and a carboxylic acid. A light wavelength conversion particle comprising a step of curing a light wavelength conversion composition containing at least one of them and a polymerizable compound to obtain a cured product of the light wavelength conversion composition, and a step of crushing the cured product. A manufacturing method is provided.

According to another aspect of the present invention, the method for producing an optical wavelength conversion particle, which comprises a compound containing quantum dots and one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, and a carboxylic acid. A step of granularly dispersing a light wavelength conversion composition containing at least one of them and a polymerizable compound in a poor solvent, and polymerizing the polymerizable compound in a state of granularly dispersing the light wavelength conversion composition. A method for producing a light wavelength conversion particle is provided, which comprises a step of causing the light wavelength to be converted.

In the above production method, the polymerization of the polymerizable compound may be suspension polymerization or emulsion polymerization.

According to one aspect and the other aspect of the present invention, quantum dots are encapsulated in 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. Therefore, light wavelength conversion particles having excellent heat resistance and moisture heat resistance can be obtained. According to another aspect of the present invention, it is possible to provide a light wavelength conversion particle dispersion liquid and a light wavelength conversion composition containing such light wavelength conversion particles. Further, according to another aspect of the present invention, since the light wavelength conversion member or the light wavelength conversion sheet contains the above-mentioned light wavelength conversion particles, the light wavelength conversion member and the light wavelength have excellent heat resistance and moisture heat resistance. A conversion sheet, a backlight device including such a light wavelength conversion member or a light wavelength conversion sheet, and an image display device can be provided.

It is a schematic block diagram of the light wavelength conversion particle which concerns on embodiment. It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows the operation of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. FIG. 6 is a cross-sectional view taken along the line I-I of the optical wavelength conversion sheet of FIG. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of another light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows typically the manufacturing process of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the image display device including the backlight device which concerns on embodiment. It is a perspective view of the lens sheet shown in FIG. FIG. 3 is a cross-sectional view taken along the line II-II of the lens sheet of FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown in FIG. It is a schematic block diagram of another backlight apparatus which concerns on embodiment. FIG. 8 is an enlarged view of the vicinity of the light entering surface of the optical plate shown in FIG.

Hereinafter, the drawings of the light wavelength conversion particle, the light wavelength conversion dispersion, the light wavelength conversion composition, the light wavelength conversion member, the light wavelength conversion sheet, the backlight device, and the image display device according to the embodiment of the present invention will be referred to. I will explain while. In the present specification, terms such as "sheet" and "film" are not distinguished from each other based only on the difference in designation. Therefore, for example, "sheet" is used to include a member that can also be called a film, and "film" is used to include a member that can also be called a sheet. FIG. 1 is a schematic configuration diagram of an optical wavelength conversion particle according to the present embodiment, FIG. 2 is a schematic configuration diagram of an optical wavelength conversion sheet according to the present embodiment, and FIG. 3 is a schematic configuration diagram of an optical wavelength conversion sheet according to the present embodiment. 4 to 6, 8 and 9 are schematic configuration diagrams of other optical wavelength conversion sheets according to the present embodiment, and FIG. 7 is I of the optical wavelength conversion sheet of FIG. It is a cross-sectional view along the −I line, and FIGS. 10 and 11 are diagrams schematically showing a manufacturing process of an optical wavelength conversion sheet according to the present embodiment.

<<< Light wavelength conversion particles >>>
The light wavelength conversion particle 1 shown in FIG. 1 is a particle that converts the wavelength of incident light into another wavelength. The light wavelength conversion particle 1 is a resin particle containing at least one of 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. 2 and one or more quantum dots 3 contained in the resin particles 2. The light wavelength conversion particles 1 shown in FIG. 1 further include a coating layer 4 that covers the surface of the resin particles 2. The light wavelength conversion particle 1 does not have to include the coating layer 4 as long as it includes the resin particles 2 and the quantum dots 3.

In the light wavelength conversion particle 1, the content of a specific element in the light wavelength conversion particle 1 measured by fluorescent X-ray analysis (XRF) is preferably 0.5% by mass or more. If the content of the specific element is less than 0.5% by mass, the deterioration of the quantum dots may not be 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 1 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. If the content of the specific element exceeds 20% by mass, sufficient curing may not be performed when the light wavelength conversion particles are formed. 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 1 is preferably twice or more the average particle size of the quantum dots 3. When the average particle size of the light wavelength conversion particles 1 is twice or more the average particle size of the quantum dots 3, the distance from the quantum dots 3 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 3 from oxygen can be further suppressed. The average particle size of the light wavelength conversion particle 1 is obtained by measuring the particle size of 20 light wavelength conversion particles in the observation of the light wavelength conversion particle with a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), and averaging the particle size. It can be obtained by calculating the value. The average particle size of the quantum dots 3 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 1 is preferably 10 nm or more and 100 μm or less. If the average particle size of the light wavelength conversion particles is less than 10 nm, the deterioration of the quantum dots may not be suppressed, and if it exceeds 100 μm, the dispersibility may be deteriorated and defects may be likely to occur when processing the light wavelength conversion member. There is. The lower limit of the average particle size of the light wavelength conversion particles 1 is preferably 20 nm or more, and the upper limit of the average particle size of the light wavelength conversion particles 1 is preferably 30 μm or less, and more preferably 10 μm or less.

The shape of the light wavelength conversion particle 1 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 1 can be a true spherical value having the same volume.

It is preferable that each of the light wavelength conversion particles 1 contains one or more quantum dots 3. If the number of quantum dots contained in one optical wavelength conversion particle is less than one, the brightness may 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 1 contains two or more quantum dots 3, and the average distance between the quantum dots 3 in the quantum dots 3 contained in one light wavelength conversion particle 1 is 1 nm or more. Is preferable. If the average distance between the quantum dots is less than 1 nm, the luminous efficiency may decrease 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. It is more preferable that the upper limit of the average distance between the quantum dots 3 in the quantum dots 3 is 100 nm or less.

<< Resin particles >>
The resin particles 2 contain at least one of a specific element and a carboxylic acid. The resin particles 2 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 2, but from the viewpoint of preventing the elution of the specific element or carboxylic acid, it is formed in the resin particles 2 by bonding with the resin constituting the resin particles 2. 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 2, the compound containing the specific element (hereinafter, this compound is referred to as "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 2 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 2 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 2. 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 2 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 2 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, dibutyl phosphate, dimethyl vinyl phosphate, di-2-ethylhexyl hydrozen phosphate , Georail Hydrozenphosphite and the like.

<Nitrogen compounds>
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 particle 2 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.

(Ionizing radiation polymerizable compound)
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.

(Thermopolymerizable compound)
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.

<< Quantum dots >>
Quantum dots 3 are nano-sized semiconductor particles having a quantum confinement effect. The particle size and the average particle size of the quantum dots 3 are, for example, 1 nm or more and 20 nm or less. When the quantum dot 3 absorbs light from the excitation source and reaches an energy excited state, the quantum dot 3 emits energy corresponding to the energy band gap of the quantum dot 3. Therefore, by adjusting the particle size or the composition of the substance of the quantum dots 3, the energy band gap can be adjusted, and energy in various levels of wavelength bands can be obtained. In particular, the quantum dots 3 can generate strong fluorescence in a narrow wavelength band.

Specifically, the energy band gap of the quantum dots 3 increases as the particle size decreases. That is, as the crystal size becomes smaller, the emission of the quantum dots 3 shifts to the blue side, that is, to the high energy side. Therefore, by changing the particle size of the quantum dot 3, 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 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 3, 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. The quantum dot 3 shown in FIG. 1 includes a first quantum dot 3A and a second quantum dot 3B having an emission band in a wavelength range different from that of the first quantum dot 3A.

The quantum dots 3 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 3 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.

<< Coating layer >>
The coating layer 4 covers the surface of the resin particles 3. The coating layer 4 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 4 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 4 depends on the function exhibited by the coating layer 4, 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 4 exerts a barrier property-imparting function, the film thickness of the coating layer 4 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 4 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 4 is 50 nm or more and 300 nm or less from the viewpoint of suppressing reflection on the surface of 1 and efficiently incorporating the excitation light into the resin particles 2. The film thickness of the coating layer 4 is determined by photographing a cross section of the light wavelength conversion particle 1 using a scanning electron microscope (SEM) and measuring the film thickness of the light wavelength conversion particle 1 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 4, when the coating layer 4 has a function of retaining the shape of the resin particles, the coating layer 4 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 2, 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, and when the resin particles are formed of a thermopolymerizable compound, it is preferably formed using a composition for a coating layer containing the thermopolymerizable compound.

When a barrier layer that suppresses the permeation of water and oxygen is formed as the coating layer 4, 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 16 described later. 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 16 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.

<<< Manufacturing method of light wavelength conversion particles >>>
Such light wavelength conversion particles 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 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.

It is considered that the reason why quantum dots are easily deteriorated by heat resistance test and moisture heat resistance test is as follows. First, as described above, a ligand composed of a sulfur-based compound, a phosphorus-based compound, or the like is coordinated on the surface of the quantum dot, and this ligand is easily desorbed by light or heat. When the ligand is desorbed from the quantum dots, water and oxygen are likely to adhere to the quantum dots, so that the quantum dots are oxidized and deteriorated. As a result, it is considered that the quantum dots are deteriorated by the heat resistance test and the moisture heat resistance test. On the other hand, in the present embodiment, since the resin particles 2 surrounding the quantum dots 3 contain at least one of one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen and a carboxylic acid, the quantum particles 2 are contained. 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 dots 3, whereby the light wavelength conversion particles 1 having excellent heat resistance and moist heat resistance can be obtained. This is a function that at least one of the sulfur component, the phosphorus component, the nitrogen component and the carboxylic acid present in the resin particle 2 assists the role of the ligand even when the ligand is desorbed from the quantum dots ( For example, it binds to quantum dots instead of ligands and exerts at least one of the functions of substituting the ligand and capturing oxygen), which is considered to be because the deterioration of the quantum dots is suppressed. ..

As described above, in the present embodiment, the resin particles 2 that enclose the quantum dots 3 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 3 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 4 is a barrier layer that suppresses the permeation of water and oxygen, the resin particles 2 are formed by the barrier layer even when a part of the quantum dots 3 is exposed on the surface of the resin particles 2. Since the contact between the quantum dots 3 partially exposed from the surface and moisture or oxygen can be suppressed, the deterioration of the quantum dots can be further suppressed. Thereby, the light wavelength conversion particle 1 having more excellent heat resistance and moisture heat resistance can be obtained.

When quantum dots are directly encapsulated in glass particles, the infiltration of water and oxygen can be suppressed, but since they are brittle, defects due to cracks occur during manufacturing, processing, heat resistance test, and moisture heat resistance test. It is easy to obtain light wavelength conversion particles having stable quality. On the other hand, in the present embodiment, since the quantum dots 3 are included in the resin particles 2, it has excellent flexibility and can suppress defects due to cracks. Thereby, the light wavelength conversion particle 1 having stable quality can be provided. When the coating layer 4 is a barrier layer, it has more flexibility than the case where the quantum dots are directly encapsulated in the glass particles, and defects due to cracks can be suppressed.

<<< Light wavelength conversion particle dispersion >>>
The light wavelength conversion particle dispersion liquid contains a dispersion medium and light wavelength conversion particles 1 dispersed in the dispersion medium. The dispersion medium is not particularly limited, and examples thereof include water; alcohols such as methanol, ethanol, propanol and isopropyl alcohol; ketones such as methyl ethyl ketone and methyl isobutyl ketone, toluene and cyclohexane. Among these, ethanol and toluene are preferable from the viewpoint of improving the dispersibility of the quantum dots.

The content of the light wavelength-converted particles 1 in the light-wavelength-converted particle dispersion is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less. If the content of the light wavelength conversion particles is less than 1% by mass, a sufficient wavelength conversion function may not be obtained, and if the content of the light wavelength conversion particles 1 exceeds 50% by mass, precipitation occurs. Therefore, the dispersibility in the dispersion may be insufficient.

<<< Light wavelength conversion composition >>>
The light wavelength conversion composition contains light wavelength conversion particles 1 and a polymerizable compound that becomes a binder resin 16 described later after curing. The light wavelength conversion composition may further contain a polymerization initiator in addition to the light wavelength conversion particles 1 and the polymerizable compound. The light wavelength conversion composition preferably further contains light-scattering particles, and may also contain additives and solvents.

The viscosity of the optical wavelength conversion composition is preferably 10 mPa · s or more and 10000 mPa · s or less. If the viscosity of the light wavelength conversion composition is less than 10 mPa · s, it may be difficult to form a sufficient film thickness, and if it exceeds 10000 mPa · s, when the light wavelength conversion composition is applied, it may be difficult to form a sufficient film thickness. It becomes difficult to apply and the leveling property may deteriorate. The lower limit of the viscosity of the light wavelength conversion composition is preferably 10 mPa · s or more, and the upper limit of the viscosity of the light wavelength conversion composition 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 light wavelength conversion composition 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. If the content of the light wavelength conversion particles is less than 1% by mass, sufficient emission intensity may not be obtained, and if the content of the light wavelength conversion particles exceeds 40% by mass, processing during film formation May be difficult.

The content of the polymerizable compound with respect to the total solid content mass of the light wavelength conversion composition is preferably 30% by mass or more, and preferably 50% by mass or more and 99% by mass or less. If the content of the polymerizable compound is less than 30% by mass, sufficient curability may not be obtained when the light wavelength conversion composition is cured. When the light wavelength conversion composition 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. To do.

<< Polymerizable compound >>
Since the polymerizable compound is the same as the polymerizable compound described in the resin particles 2, the description thereof will be omitted here.

<< 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 light wavelength conversion composition is preferably 0.3 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. If the content of the polymerization initiator is less than 0.3 parts by mass, the polymerizable compound is difficult to cure, and if it exceeds 5.0 parts by mass, the optical wavelength conversion sheet may turn yellow. ..

<< Light-scattering particles >>
The light scattering particles are particles having an action of changing the traveling direction of light by scattering the light that has entered the light wavelength conversion layer or the light wavelength conversion unit, which will be described later.

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 less than 20 times the average particle size of the quantum dots, sufficient light scattering performance may not be obtained in the light wavelength conversion layer or the light wavelength conversion unit, and the light scattering particles may not have sufficient light scattering performance. When the average particle size of the particles exceeds 2000 times the average particle size of the quantum dots, the number of light-scattering particles decreases even if the amount of addition is the same, so that the number of scattering points decreases and a sufficient light scattering effect is obtained. It may not be possible. 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 described later. preferable. If the average particle size of the light scattering particles is less than 1/300 of the average film thickness of the light wavelength conversion layer, sufficient light scattering performance may not be obtained in the light wavelength conversion layer, and the average of the light scattering particles. If the particle size exceeds 1/20 of the average film thickness of the light wavelength conversion layer, the ratio of light scattering particles to the light wavelength conversion member decreases even if the amount added is the same, so that the number of scattering points is sufficiently reduced. No light scattering effect can be obtained.

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

The shape of the light-scattering particles 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 is preferable to have 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 on the wavelength conversion sheet can be suitably scattered and the light wavelength conversion efficiency with respect to the incident light can be preferably improved.

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. Since the light wavelength conversion efficiency with respect to the incident light can be more preferably improved by the light wavelength conversion sheet 10, the light scattering particles may be made of two or more kinds of materials.

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

<< Additives >>
The additive is not particularly limited, but a compound that suppresses oxidation and deterioration of quantum dots is preferable. Examples of the compound that suppresses oxidation and deterioration of quantum dots include phenol-based compounds, amine-based compounds, sulfur-based compounds, carbosixi group-containing compounds, hydrazine-based compounds, amide-based compounds, and hindered amine-based compounds. The additive may have a polymerizable functional group such as an ionizing radiation polymerizable functional group or a thermally polymerizable functional group.

<< 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.

<<< Light wavelength conversion member >>>
The light wavelength conversion member includes the light wavelength conversion particles 1. The shape and structure of the light wavelength conversion member can be appropriately changed depending on the location where the light wavelength conversion member is incorporated or the like. For example, the light wavelength conversion member may be a light wavelength conversion sheet as described below, a light source described later, or a capillary installed in the vicinity of the light source. Further, the light wavelength conversion member may be a color filter. When the light wavelength conversion member is a color filter, for example, a light wavelength conversion layer containing light wavelength conversion particles containing blue emission quantum dots is used instead of the blue coloring layer, and green emission quantum dots are used instead of the green coloring layer. The light wavelength conversion layer containing the light wavelength conversion particles containing the above may be used, and the light wavelength conversion layer containing the light wavelength conversion particles containing the red emission quantum dots may be used instead of the red colored layer.

<<< Light wavelength conversion sheet >>>
The light wavelength conversion sheet 10 shown in FIG. 2 is a form of a light wavelength conversion member, which converts the wavelength of a part of the incident light into another wavelength, and the other part of the incident light and the other part of the incident light. It is a sheet that emits wavelength-converted light. The light wavelength conversion sheet 10 shown in FIG. 2 is a light wavelength conversion layer 11, light transmissive base materials 12 and 13 provided on both sides of the light wavelength conversion layer 11, and light in the light transmissive base materials 12 and 13. It includes light diffusion layers 14 and 15 provided on the side opposite to the surface on the wavelength conversion layer 11 side.

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

In the optical wavelength conversion sheet 10, as shown in FIG. 3, when light is incident from the surface 10A of the optical wavelength conversion sheet 10, the light L1 incident on the quantum dots 3 in the optical wavelength conversion layer 11 is generated. It is converted into light L2 having a wavelength different from that of light L1 and emitted from the surface 10B. On the other hand, even when light is incident from the surface 10A, the light L1 passing between the quantum dots 3 in the optical wavelength conversion layer 11 is emitted from the surface 10B without being wavelength-converted.

In the light wavelength conversion sheet 10, since the light wavelength conversion particles 1 have excellent heat resistance and moisture heat resistance, the water vapor transmittance (WVTR: Water Vapor Transmission Rate) at 40 ° C. and 90% relative humidity is obtained in the entire sheet. 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. Since a barrier film is formed on the conventional light wavelength conversion sheet, the light wavelength conversion sheet 10 has a higher water vapor transmittance than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher water vapor transmittance. Moisture is more easily transmitted than the conventional light wavelength conversion sheet. As will be described later, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the water vapor transmittance is the water vapor transmittance of the entire light wavelength conversion sheet including the optical member.

In the light wavelength conversion sheet 10, since the light wavelength conversion particles 1 have excellent heat resistance and moisture heat resistance, the oxygen transmission rate (OTR: Oxygen Transmission Rate) at 23 ° C. and 90% relative humidity is 0 for the entire sheet. ^{.1cm 3 / (m 2 · 24h} · atm) may be equal to or greater than. The light wavelength conversion sheet 10 may satisfy the water vapor transmittance and the oxygen transmittance at the same time. The oxygen permeability is a numerical value obtained by a method based on JIS K7126: 2006. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON). The oxygen permeability shall be the average value of the values obtained by measuring three times. Since the conventional light wavelength conversion sheet has a barrier film formed therein, the light wavelength conversion sheet 10 has a higher oxygen transmittance than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 has a higher oxygen transmittance. Compared to the conventional light wavelength conversion sheet, not only water but also oxygen is easily transmitted. Similarly to the above, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion layer, the oxygen transmittance is the oxygen transmittance of the entire light wavelength conversion sheet including the optical member.

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

The internal haze value of the optical wavelength conversion sheet 10 is preferably 50% or more. The internal haze is a haze value caused by the inside of the light wavelength conversion sheet, and does not take into account the uneven shape of the surface of the light wavelength conversion sheet. When the internal haze value of the optical wavelength conversion sheet 10 is 50% or more, the light can be sufficiently diffused by the internal haze to excite the quantum dots multiple times, and the external haze value can be made smaller. Can be done. The internal haze value of the optical wavelength conversion sheet 10 is preferably 60% or more, and more preferably 80% or more.

The external haze value in the optical wavelength conversion sheet 10 is preferably 10% or less (including 0%), and more preferably 5% or less. The external haze value is caused only by the uneven shape of the surface of the optical wavelength conversion sheet. When the external haze value of the light wavelength conversion sheet 10 is 10% or less, retroreflection is likely to occur in a retroreflective sheet such as a lens sheet.

In the light wavelength conversion sheet 10, it is preferable that the external haze value of the light wavelength conversion sheet 10 is smaller than the internal haze value of the light wavelength conversion sheet 10. That is, it is preferable that the light wavelength conversion sheet 10 satisfies the relationship of the following formula.
Internal haze value> External haze value

The internal haze value and the external haze value can be obtained using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute). Specifically, first, using a haze meter, the total haze value of the optical wavelength conversion sheet is measured according to JIS K7136: 2000. After that, a triacetyl cellulose base material having a thickness of 60 μm (product name “Panaclean PD-S1”, manufactured by Panadium Co., Ltd.) is interposed on both sides of the optical wavelength conversion sheet via a transparent optical adhesive layer having a thickness of 25 μm (product name “Panaclean PD-S1”). TD60UL ", manufactured by Fujifilm Co., Ltd.) is pasted. As a result, the uneven shape of the surface of the light wavelength conversion sheet is crushed, and the surface of the light wavelength conversion sheet is flattened. Then, in this state, the internal haze value is obtained by measuring the haze value according to JIS K7136: 2000 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute). The external haze value is obtained by subtracting the internal haze from the total haze. The "external haze value" in the present specification means the external haze value of the entire light wavelength conversion sheet. That is, the external haze value in the present specification means the sum of the external haze value on one surface of the light wavelength conversion sheet and the external haze value on the other surface of the light wavelength conversion sheet. The internal haze value and the external haze value shall be the arithmetic mean values of the values obtained by measuring each of the three times.

The internal haze value and the external haze value are related. Specifically, as the internal haze value increases, the external haze tends to decrease even if the surface has the same surface irregularities. This is considered to be due to the following reasons. JIS K7136: 2000 stipulates that haze is a percentage of transmitted light passing through a test piece that deviates by 0.044 rad (2.5 °) or more from incident light due to forward scattering. There is. That is, in the definition of haze, transmitted light deviated by 2.5 ° or more with respect to incident light is measured as haze, but transmitted light less than 2.5 ° with respect to incident light is not measured as haze. On the other hand, in the light wavelength conversion sheet having a large internal haze, the light is scattered more inside the sheet as compared with the light wavelength conversion sheet having a smaller internal haze. Transmitted light below 2.5 ° is reduced. Therefore, when the optical wavelength conversion sheet having a large internal haze and the optical wavelength conversion sheet having a smaller internal haze have the same surface unevenness, the optical wavelength conversion sheet having a larger internal haze has a larger internal haze than that. Compared to a small light wavelength conversion sheet, the influence of surface irregularities is reduced. Therefore, when considering only the influence of the surface unevenness existing on the sheet surface, even if the light wavelength conversion sheet having a large internal haze and the light wavelength conversion sheet having a smaller internal haze have the same surface unevenness, the inside Compared to the light wavelength conversion sheet with a smaller internal haze, the light wavelength conversion sheet with a large haze has not only transmitted light of less than 2.5 ° with respect to the incident light emitted from the surface unevenness, but also the surface unevenness. The transmitted light that deviates by 2.5 ° or more with respect to the incident light emitted from the light is also reduced. Therefore, it is considered that when the internal haze value becomes large, the external haze becomes small even if the same surface unevenness is provided.

In the light wavelength conversion sheet 10, in order to make the external haze value of the light wavelength conversion sheet 10 smaller than that of the light wavelength conversion sheet 10, for example, adding light scattering particles to the inside of the light wavelength conversion sheet 10 can be mentioned. .. When the light wavelength conversion sheet includes at least one of a barrier film and a light diffusing layer, the light scattering particles may be added to the barrier film in addition to the light wavelength conversion layer 11, and light. It may also be added in the diffusion layer. When the layer to which the light scattering particles are added is the outermost layer, it may be accompanied by an outer haze. Therefore, by controlling the surface unevenness of the outermost layer, the above-mentioned relationship between the inner haze and the outer haze is satisfied. Can be done.

The ratio of the external haze value to the internal haze value (external haze value / internal haze value) in the optical wavelength conversion sheet 10 is preferably 0 or more and 0.1 or less, and more preferably 0 or more and 0.05 or less. .. If this ratio is within this range, the internal haze can sufficiently diffuse the light and excite the quantum dots multiple times.

The arithmetic mean roughness (Ra) of the surfaces 10A and 10B of the optical wavelength conversion sheet 10 is preferably 0.1 μm or more, and more preferably 0.5 μm or more, respectively. The Ra of the surfaces 10A and 10B of the optical wavelength conversion sheet 10 is preferably 0.1 μm for the following reasons. The optical wavelength conversion sheet comes into contact with the optical plate or lens sheet described later in the backlight device, but if the optical wavelength conversion sheet and the optical plate or lens sheet stick to each other, the space between the optical wavelength conversion sheet and the optical plate Since there is a risk that a pattern called wetout, which looks like wetting with water, may be formed at the interface between the light wavelength conversion sheet 10 and the optical wavelength conversion sheet and the lens sheet. Ra is more preferably 0.1 μm or more in order to prevent sticking.

The above definition of "Ra" shall be in accordance with JIS B0601: 1994. Ra can be measured using, for example, a surface roughness measuring instrument (product name "SE-3400", manufactured by Kosaka Laboratory Co., Ltd.). Ra is an arithmetic mean value obtained by randomly measuring 15 points on the surfaces 10A and 10B of the light wavelength conversion sheet 10 where there is no visual abnormality (where there are no large foreign substances or scratches). ..

When a light wavelength conversion sheet 10 containing both quantum dots that convert blue light into green light and quantum dots that convert blue light into red light is irradiated with a light source that emits blue light, the transmitted light in the light wavelength conversion sheet. Of these, the ratio of the peak value of green light intensity to the peak value of blue light intensity (peak value of green light intensity / peak value of blue light intensity) is 0.3 or more and 2.0 or less. It is preferably 0.5 or more and 1.5 or less.

Further, the ratio of the peak value of the light intensity of red light to the peak value of the light intensity of blue light (the peak value of the light intensity of red light / the peak value of the light intensity of blue light) in the transmitted light in the light wavelength conversion sheet 10 is , 0.3 or more and 2.0 or less, and more preferably 0.5 or more and 1.5 or less.

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.).

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

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

<< Optical wavelength conversion layer >>
The light wavelength conversion layer 11 contains the light wavelength conversion particles 1 and the binder resin 16 which is a cured product of the polymerizable compound. The light wavelength conversion layer 11 shown in FIG. 2 further contains light scattering particles 17. By including the light scattering particles 17, the light wavelength conversion efficiency and the internal haze can be improved. Since the light scattering particles 17 included in the light wavelength conversion layer 11 are the same as the light scattering particles described above, the description thereof will be omitted here.

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

The absolute value of the difference in refractive index between the light-scattering particles 17 and the binder resin 16 is preferably 0.05 or more, and more preferably 0.10 or more, from the viewpoint of obtaining sufficient light scattering. The refractive index of the light-scattering particles 17 and the refractive index of the binder resin 16 may be larger. Here, as a method for measuring the refractive index of the light scattering particles before being contained in the light wavelength conversion layer, for example, the Becke method, the minimum declination method, the declination analysis, the mode line method, the ellipsometry method and the like are used. can do. Further, the refractive index of the binder resin 16 in the light wavelength conversion layer 11 is determined by, for example, taking out 10 pieces of the binder resin 16 from the light wavelength conversion layer 11 by cutting out or the like, and using the Becke method in the 10 pieces taken out. The refractive index of the binder resin 16 can be measured, and can be obtained as an average value of 10 of the measured refractive indexes of the binder resin 16. Further, the refractive index of the light scattering particles 17 is determined by, for example, taking out a fragment from the binder resin 16 in which a part of the surface of the light scattering particles 17 is exposed by cutting out from the light wavelength conversion layer 11 and the like. The refractive indexes of the 10 light-scattering particles 17 whose surfaces are exposed by the Becke method are measured, and can be obtained as an average value of 10 of the measured refractive indexes of the light-scattering particles 17. 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 a standard solution is used as the refractive index of a binder resin or light-scattering particles. When the surface of the light-scattering particles is not exposed in the removed pieces, the surface of the light-scattering particles is covered with the binder resin, so that the light-scattering particles are covered with the binder resin existing around the light-scattering particles. There is no difference in refractive index. Therefore, it is possible to determine whether or not a part of the surface of the light scattering particles is exposed by measuring the difference in refractive index from the binder resin existing around the light scattering particles by the Becke method or the like. .. In addition, the difference in refractive index between the binder resin and the light-scattering particles is measured using a phase-shift laser interference microscope (such as a phase-shift laser interference microscope manufactured by FK Optical Laboratory or a diketric interference microscope manufactured by Mizojiri Optical Co., Ltd.). can do.

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

The thickness of the light-transmitting base materials 12 and 13 can be determined by using a scanning electron microscope (SEM), a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) to obtain a cross section of the light-transmitting base materials 12 and 13. Is taken, and the thicknesses of the light-transmitting substrates 12 and 13 are measured at 20 points in the image of the cross section, and the average value of the film thicknesses at the 20 points is used.

Examples of the constituent raw materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulphon, and poly sulphon. , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyetherketone, polymethylmethacrylate, polycarbonate, polyurethane and the like. Preferred examples of the constituent materials of the light-transmitting base materials 12 and 13 include polyester (for example, polyethylene terephthalate and polyethylene naphthalate).

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

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

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

The average particle size of the light-scattering particles in the light diffusing layers 14 and 15 is preferably 10 times or more and 20,000 times or less, and more preferably 10 to 5000 times the average particle size of the quantum dots 3 described above. preferable. If the average particle size of the light-scattering particles is less than 10 times the average particle size of the quantum dots, sufficient light-diffusiveness may not be obtained in the light-diffusing layer, and the average particle size of the light-scattering particles may not be sufficient. When it exceeds 20,000 times the average particle size of the quantum dots, the light diffusion performance of the light diffusion layer becomes excellent, but the light transmission rate of the light diffusion layer tends to be significantly reduced. The average particle size of the light-scattering particles can be measured by the same method as the average particle size of the quantum dots described above.

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

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

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

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

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

<< Other optical wavelength conversion sheets >>
As shown in FIG. 4, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 20 having only the optical wavelength conversion layer 11 (single layer structure). Further, as shown in FIG. 5, the light wavelength conversion sheet may be a light wavelength conversion sheet 30 including a light wavelength conversion layer 11 and a light transmissive base material 31 that supports the light wavelength conversion layer 11. .. By providing the light transmissive base material 31, the intensity of the light wavelength conversion sheet can be increased as compared with the light wavelength conversion sheet 20.

<Light transmissive base material>
As the light-transmitting base material 31 of the light wavelength conversion sheet 30, the same materials as those of the light-transmitting base materials 12 and 13 can be used, and thus the description thereof will be omitted here.

<< Other optical wavelength conversion sheets >>
As shown in FIGS. 6 and 7, the optical wavelength conversion sheet is arranged on at least one surface side of the optical wavelength conversion layer 11 and the optical wavelength conversion layer 11, and is integrated with the optical wavelength conversion layer 11. The optical wavelength conversion sheet 40 including the optical member 41 may be used.

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

As shown in FIGS. 6 and 7, the optical member 41 includes a light-transmitting base material 42 and a lens layer 43 provided on one surface of the light-transmitting base material 42. As shown in FIGS. 5 and 6, the lens layer 43 includes a sheet-shaped main body 44 and a plurality of unit lenses 45 arranged side by side on the light emitting side of the main body 44. The light transmissive base material 42, the lens layer 43, the main body portion 44, and the unit lens 45 have the same configurations as the light transmissive base material 101, the lens layer 102, the main body portion 103, and the unit lens 104, which will be described later. Therefore, the description thereof will be omitted here.

In the optical wavelength conversion sheet 40, the optical wavelength conversion layer 11 and the optical member 41 are integrated by directly applying and curing the optical wavelength conversion composition on one surface of the optical member 41. The optical wavelength conversion layer 11 and the optical member 41 may be bonded to each other via an adhesive layer.

<< Other optical wavelength conversion sheets >>
As shown in FIG. 8, the optical wavelength conversion sheet may be an optical wavelength conversion sheet 50 including an optical wavelength conversion layer 11 and overcoat layers 51 and 52 covering both surfaces of the optical wavelength conversion layer 11. In the present embodiment, the overcoat layers 51 and 52 are formed on both sides of the light wavelength conversion layer 11, but if the overcoat layer is formed on at least one surface of the light wavelength conversion layer, the light wavelength conversion is performed. It does not have to be formed on both sides of the layer 11. When the overcoat layer is provided on only one surface of the light wavelength conversion layer, a light transmissive base material may be provided on the other surface of the light wavelength conversion layer.

<Overcoat layer>
The overcoat layers 51 and 52 are layers made of a resin that covers the surface of the light wavelength conversion layer 11 and is formed by coating. Other layers such as a light diffusion layer may be formed on the overcoat layers 51 and 52.

The overcoat layers 51 and 52 are provided to prevent the light wavelength conversion layer 11 from being directly exposed to the atmosphere. By providing such overcoat layers 51 and 52 on at least one surface of the light wavelength conversion layer 11, the quantum dots 3 can be more protected from moisture and oxygen, and the light transmissive substrate can be converted to light wavelength. The thickness of the light wavelength conversion sheet can be made thinner than that provided on at least one surface of the layer 11.

The overcoat layers 51 and 52 may have some function other than the function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. Specifically, the overcoat layers 51 and 52 may be, for example, a layer having at least one of functions such as antiblocking property, light diffusing property, antistatic property, and antireflection property. When the overcoat layers 51 and 52 are layers having a function of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and some other function, the overcoat layers 51 and 52 are for having some function. The material may be added.

The film thickness of the overcoat layers 51 and 52 is 0.1 μm or more and 100 μm or less from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere and thinning the light wavelength conversion sheet. Is preferable. The film thicknesses of the overcoat layers 51 and 52 can be measured by the same method as the film thickness of the optical wavelength conversion layer 11. The lower limit of the film thickness of the overcoat layers 51 and 52 is more preferably 1 μm or more, and the upper limit is more preferably 50 μm or less.

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

The overcoat layers 51 and 52 are not particularly limited as long as they have the above hardness, but for example, (meth) acrylate compounds, epoxy compounds, combinations of isocyanates and polyols, metal alkoxides, silicon-containing resins, water-soluble polymers, and the like. Alternatively, it can be formed by using a composition for an overcoat layer containing a mixture thereof. Among these, the overcoat layers 51 and 52 are zinc acrylate, a hydrolysis product of alkoxysilane, polyvinyl alcohol, polysilazane, or these, from the viewpoint of preventing the light wavelength conversion layer 11 from being directly exposed to the atmosphere. It is preferably formed using a composition for an overcoat layer containing a mixture.

In the optical wavelength conversion sheet 20, 30, 40, 50, the entire sheet, 40 ° C., water vapor transmission rate of 90% relative humidity may be a 0.1g ^/ (m 2 · 24h) or more. In the optical wavelength conversion sheet 20, 30, 40, 50, the entire sheet, 23 ° C., even oxygen permeability at a relative humidity of 90% has become a ^{0.1cm 3 / (m 2 · 24h} · atm) or higher Good. 40 ° C. in the optical wavelength conversion sheet 20, 30, 40, 50, the water vapor transmission rate of 90% relative humidity may be made with 1g ^/ (m 2 · 24h) or more, the optical wavelength conversion sheet 20, 30, 23 ° C. in 40 and 50, the oxygen permeability at 90% relative humidity may be a ^{1cm 3 / (m 2 · 24h} · atm) or more.

<< Other optical wavelength conversion sheets >>
The optical wavelength conversion sheet may be an optical wavelength conversion sheet 60 as shown in FIG. In this case, the water vapor transmittance and the oxygen transmittance of the light wavelength conversion sheet 60 do not have to be within the above-mentioned ranges.

The light wavelength conversion sheet 60 shown in FIG. 8 is the light wavelength conversion layer 11, the barrier films 61 and 62 provided on both sides of the light wavelength conversion layer 11, and the light wavelength conversion layer 11 side of the barrier films 61 and 62. It is provided with light diffusion layers 13 and 14 provided on the side opposite to the surface. In the light wavelength conversion sheet 60, the surfaces of the light diffusion layers 13 and 14 constitute the surfaces 60A and 60B of the light wavelength conversion sheet 60.

<Barrier film>
The barrier films 61 and 62 are members for suppressing the permeation of water and oxygen to protect the quantum dots 3 from water and oxygen. Here, the "barrier film" herein is a member alone, 40 ° C., water vapor transmission rate of 90% relative humidity becomes 0.1g ^/ (m 2 · 24h) below, and 23 ° C., relative humidity oxygen transmission rate at 90% is intended to mean a member made of a ^{0.1cm 3 / (m 2 · 24h} · atm) of less than. The barrier film includes not only a single-layer structure film but also a multi-layer structure film. By installing the barrier films 61 and 62 with the light wavelength conversion layer 11 sandwiched between them, the heat resistance and moisture resistance of the quantum dots 3 can be further improved. The barrier films 61 and 62 shown in FIG. 8 are provided on the light transmissive base materials 12 and 13 and the light wavelength conversion layer 11 side of the light transmissive base materials 12 and 13, and suppress the permeation of water and oxygen. It includes barrier layers 63 and 64 having a function.

Water vapor permeability of the barrier film 61,62 (WVTR: Water Vapor Transmission Rate ) is, 40 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 g} / (m 2 · 24h) that less is Is more preferable. The water vapor transmission rate can be measured using a water vapor transmission rate measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON).

Oxygen permeability of the barrier film 61,62 (OTR: Oxygen Transmission Rate) is, 23 ° C., at a relative humidity of ^{90%, 1.0 × 10 -2 cm} 3 / (m 2 · 24h · atm) or less It is more preferable to have. The oxygen permeability can be measured using an oxygen gas permeability measuring device (product name "OX-TRAN 2/21", manufactured by MOCON).

(Barrier layer)
The barrier layers 63 and 64 are composed of a thin-film deposition layer having a function of suppressing the permeation of water and oxygen. The thin-film deposition layer is a layer formed by a vapor deposition method such as a physical vapor deposition (PVD) method such as a sputtering method or an ion plating method or a chemical vapor deposition (CVD) method. The thin-film deposition layer has the advantage that the barrier property can be enhanced.

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

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

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

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

Next, the coating film of the composition for the light diffusion layer is cured by light irradiation or the like. As a result, as shown in FIG. 10A, the light diffusing layer 14 is formed on one surface of the light transmitting base material 12, and the light transmitting base material 12 with the light diffusing layer 14 is formed. Further, although not shown, the light transmissive base material 13 with the light diffusing layer 15 is formed in the same manner.

After forming the light-transmitting base material 13 with the light-diffusing layer 15, as shown in FIG. 10B, the side of the light-transmitting base material 13 with the light-diffusing layer 15 opposite to the surface on the light-diffusing layer 15 side. The light wavelength conversion composition is applied to the surface of the surface and dried to form a coating film 18 of the light wavelength conversion composition.

After forming the coating film 18 of the light wavelength conversion composition, as shown in FIG. 11 (A), the surface of the light transmissive substrate 12 with the light diffusing layer 14 opposite to the surface on the light diffusing layer 14 side is the light wavelength. The light transmissive base material 12 with the light diffusion layer 14 is arranged on the coating film 18 of the light wavelength conversion composition so as to be in contact with the coating film 18 of the conversion composition. As a result, the coating film 18 of the light wavelength conversion composition is sandwiched between the light transmitting base materials 12 and 13.

Next, as shown in FIG. 11B, the coating film 18 of the light wavelength conversion composition is irradiated with ionizing radiation or heat is applied to cure the polymerizable compound via the light transmitting substrate 12. The light wavelength conversion layer 11 is formed, and the light wavelength conversion layer 11 is integrated with the light transmission base material 12 with the light diffusion layer 14 and the light transmission base material 13 with the light diffusion layer 15. As a result, the optical wavelength conversion sheet 10 shown in FIG. 2 is obtained.

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

The optical wavelength conversion sheets 20, 30 and 50 can be produced, for example, as follows. First, the above-mentioned light wavelength conversion composition is applied onto a base material (not shown) and dried to form a coating film of the light wavelength conversion composition. Then, the light wavelength conversion layer 11 is formed by irradiating the coating film with ionizing radiation or applying heat to cure the polymerizable compound. Then, the base material is peeled off from the light wavelength conversion layer 11. As a result, the optical wavelength conversion sheet 20 shown in FIG. 4 is obtained. On the other hand, when the light transmissive base material 31 is used as the base material, the light wavelength conversion sheet 30 shown in FIG. 5 can be obtained by leaving the base material as it is without peeling it from the light wavelength conversion layer 11. can get. In the light wavelength conversion sheet 50 shown in FIG. 8, the composition for the overcoat layer is applied to at least one surface of the light wavelength conversion sheet 20 to form a coating film of the composition for the overcoat layer, and this coating film is formed. Can be formed by curing. The light wavelength conversion sheet 50 can also be formed by the following method. First, the composition for the overcoat layer is applied to one surface of the two substrates to form a coating film of the composition for the overcoat layer. After forming the coating film, the coating film of each overcoat layer composition is irradiated with ionizing radiation or heated to form an overcoat layer. After forming the overcoat layer, the light wavelength conversion composition is applied onto the overcoat layer formed on one of the base materials to form a coating film of the light wavelength conversion composition. Next, the other base material is placed on the coating film of the light wavelength conversion composition so that the overcoat layer formed on the other base material is in contact with the coating film of the light wavelength conversion composition. Next, in this state, the coating film of the light wavelength conversion composition is irradiated with ionizing radiation or heat is applied to form a light wavelength conversion layer, and the light wavelength conversion layer and the overcoat layer are integrated. Let me. Finally, when both substrates are peeled off, the light wavelength conversion sheet 50 shown in FIG. 8 is obtained.

The light wavelength conversion sheet 40 is coated with the light wavelength conversion composition on one surface side of the optical member 41 and dried to form a coating film of the light wavelength conversion composition. Then, the light wavelength conversion layer 11 is formed by irradiating the coating film with ionizing radiation or applying heat to cure the polymerizable compound. As a result, the optical wavelength conversion sheet 40 shown in FIG. 6 is obtained.

The light wavelength conversion sheet 60 is a barrier in which the light diffusion layers 14 and 15 are provided with the light transmitting base materials 12 and 13 and the barrier layers 63 and 64 formed on one surface of the light transmitting base materials 12 and 13. If it is formed on the films 61 and 62, it can be formed by the same process as the light wavelength conversion sheet 10.

The optical wavelength conversion sheets 10, 20, 30, 40, 50, 60 can be used by being incorporated in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion sheet 10 is incorporated into a backlight device and an image display device will be described. FIG. 12 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, FIG. 13 is a perspective view of the lens sheet shown in FIG. 12, and FIG. 14 is a perspective view of the lens sheet of FIG. It is sectional drawing along line II. 15, 16 and 18 are schematic configuration diagrams of other backlight devices according to the present embodiment, FIG. 17 is a schematic configuration diagram of the light source shown in FIG. 16, and FIG. 19 is a schematic configuration diagram of the light source shown in FIG. It is an enlarged view near the light source surface of an optical plate.

<<< Image display device >>>
The image display device 70 shown in FIG. 12 includes a backlight device 80 and a display panel 120 arranged on the light emitting side of the backlight device 80. The image display device 70 has a display surface 70A for displaying an image. In the image display device 70 shown in FIG. 12, the surface of the display panel 120 is the display surface 70A.

The backlight device 80 illuminates the display panel 120 in a plane from the back side. The display panel 120 functions as a shutter that controls the transmission or blocking of light from the backlight device 80 for each pixel, and is configured to display an image on the display surface 70A.

<< Display panel >>
The display panel 120 shown in FIG. 12 is a liquid crystal display panel, and is between the polarizing plate 101 arranged on the incoming light side, the polarizing plate 122 arranged on the light emitting side, and the polarizing plate 121 and the polarizing plate 122. It includes an arranged liquid crystal cell 103. The polarizing plates 121 and 122 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 80 shown in FIG. 12 is configured as an edge light type backlight device, and includes a light source 90, an optical plate 95 as a light guide plate arranged on the side of the light source 90, and a light emitting side of the optical plate 95. The optical wavelength conversion sheet 10 arranged in the light wavelength conversion sheet 10, the lens sheet 100 arranged on the light source side of the light wavelength conversion sheet 10, the lens sheet 105 arranged on the light source side of the lens sheet 100, and the light source side of the lens sheet 105. It includes a reflective polarizing separation sheet 110 arranged, and a reflective sheet 115 arranged on the side opposite to the light source side of the optical plate 95. The backlight device 80 includes an optical plate 95, lens sheets 100 and 105, a reflective polarizing separation sheet 110, and a reflective sheet 115, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side of each member where light emitted in the direction of emission from the backlight device is emitted.

The backlight setting 80 has a light emitting surface 80A that emits light in a planar manner. In the backlight device 80 shown in FIG. 12, the light emitting surface of the reflective polarizing separation sheet 110 is the light emitting surface 80A of the backlight device 80.

The surface of the optical wavelength conversion sheet 10 on the optical plate 95 side is the surface 10A (light incoming surface), and the surface of the optical wavelength conversion sheet 10 on the lens sheet 100 side is the surface 10B (light emitting surface).

<Light source>
The light source 90 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 90 is composed of a large number of point-shaped light emitters arranged linearly on the light receiving surface 95C side of the optical plate 95, which will be described later, specifically, a large number of light emitting diodes (LEDs). ,It is configured.

Since the light wavelength conversion sheet 10 is arranged in the backlight device 80, the light source 90 can use only a light emitting body that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light having high color purity can be used.

<Optical plate>
The optical plate 95 as the light guide plate has a quadrangular shape in a plan view. The optical plate 95 extends between the light emitting surface 95A formed by one main surface on the display panel 120 side, the back surface 95B composed of the other main surface facing the light emitting surface 95A, and the light emitting surface 95A and the back surface 95B. Has sides. The side surface of the side surface on the light source 90 side is an incoming light receiving surface 75C that receives light from the light source 90. The light incident on the optical plate 95 from the light entry surface 95C is guided in the optical plate in the direction connecting the light entry surface 95C and the opposite surface facing the light entry surface 95C (light guide direction), and is guided through the optical plate. Emitted from 95A.

<Lens sheet>
The lens sheets 100 and 105 have a function of changing the traveling direction of the incident light and emitting the incident light from the light emitting side. In the present embodiment, as shown in FIG. 14, a function (condensing function) of changing the traveling direction of light L3 having a large incident angle and emitting it from the light emitting side to intensively improve the brightness in the front direction. At the same time, it has a function (retroreflection function) of reflecting light L4 having a small incident angle and returning it to the light wavelength conversion sheet 10 side. The lens sheets 100 and 105 include a light transmitting base material 101 and a lens layer 102 provided on one surface of the light transmitting base material 101.

When the surfaces 10A and 10B of the optical wavelength conversion sheet 10 are uneven surfaces, the light emitting surface 95A of the optical plate 95 is optically in close contact with a part (for example, a convex portion) of the surface 10A, and is also a surface. It is preferable that the lens sheet 100 is separated from other parts (for example, concave parts) of 10A, and the light entering surface 100A of the lens sheet 100 is optically in close contact with a part (for example, convex parts) of the surface 10B and also has a surface. It is preferable that the 10B is separated from other parts (for example, recesses). In this case, the gap between the light emitting surface 95A and the other part of the surface 10A and the gap between the light entering surface 100A and the other part of the surface 10B are an air layer. By providing this air layer, the light wavelength conversion sheet 10, the optical plate 95, and the lens sheet 100 are fixed so that the light emitting surface 95A and the surface 10A and the light entering surface 100A and the surface 10B are in optical contact with each other. However, since it is possible to prevent the light wavelength conversion sheet 10 from sticking to the optical plate 95 and the lens sheet 100, the interface between the light wavelength conversion sheet 10 and the optical plate 95 and the light wavelength conversion sheet 10 and the lens sheet 100 It is possible to suppress the formation of wet-out at the interface between the light and the light.

(Light transmissive base material)
Since the light-transmitting base material 101 is the same as the light-transmitting base materials 12 and 13, the description thereof will be omitted here.

(Lens layer)
As shown in FIGS. 13 and 14, the lens layer 102 includes a sheet-shaped main body 103 and a plurality of unit lenses 104 arranged side by side on the light emitting side of the main body 103.

The main body 103 functions as a sheet-like member that supports the unit lens 104. As shown in FIGS. 13 and 14, unit lenses 104 are arranged on the light emitting side surface 103A of the main body 103 without leaving a gap. Therefore, the light emitting surfaces 100B and 105B of the lens sheets 100 and 105 are formed by the lens surfaces. On the other hand, as shown in FIG. 14, the main body 103 has a smooth surface forming the incoming side surface of the lens layer 102 as the incoming light entering side surface 103B facing the light emitting side surface 103A.

The unit lenses 104 are arranged side by side on the light emitting side surface 103A of the main body 103. As shown in FIG. 13, the unit lens 104 extends linearly in a direction intersecting the arrangement direction AD of the unit lens 104, particularly linearly in the present embodiment. Further, in the present embodiment, a large number of unit lenses 104 included in one lens sheet 100 and 105 extend in parallel with each other. Further, the longitudinal LD of the unit lenses 104 of the lens sheets 100 and 105 is orthogonal to the arrangement direction AD of the unit lenses 104 of the lens sheets 100 and 105.

The unit lens 104 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 ND of the sheet surfaces of the lens sheets 100 and 105 and the arrangement direction AD of the unit lens 104 is a triangular shape protruding toward the light emitting side. ing. In particular, from the viewpoint of intensively improving the brightness in the front direction, the cross-sectional shape of the unit lens 104 on the main cutting surface is an isosceles triangular shape, and the apex angle located between the equilateral sides is the light emitting side surface 103A of the main body 103. Each unit lens 104 is configured so as to project from the light emitting side.

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

The dimensions of the lens sheets 100 and 105 can be set as follows, for example. First, as a specific example of the unit lens 104, the arrangement pitch of the unit lens 104 (corresponding to the width of the unit lens 104 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, the arrangement of the unit lens 104 has been rapidly improved in definition, and it is preferable that the arrangement pitch of the unit lens 104 is 10 μm or more and 50 μm or less. Further, the protruding height of the unit lens 104 from the main body 103 along the normal direction ND of the lens sheets 100 and 105 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 104 can be set to 60 ° or more and 120 ° or less.

As can be understood from FIG. 12, the arrangement direction of the unit lens 104 of the lens sheet 100 and the arrangement direction of the unit lens 104 of the lens sheet 105 intersect, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflective polarization separation sheet 110 transmits only the first linearly polarized light component (for example, P-polarized light) among the light emitted from the lens sheet 105, 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 110 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 110 again. Therefore, the reflective polarization separation sheet 110 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 105 is emitted as the light source light which is the first linearly polarized light component. Therefore, by arranging the reflective polarizing separation sheet 110, the wavelength conversion efficiency of the optical wavelength conversion sheet 10 can be further increased. Therefore, further improvement in light utilization efficiency can be expected.

As the reflective polarizing separation sheet 110, "DBEF" (registered trademark) available from 3M can be used. In addition to "DBEF", a high-intensity polarizing sheet "WRPS" available from Shinwha Intertek, a wire grid polarizer, or the like can be used as the reflective polarizing separation sheet 90.

<Reflective sheet>
The reflective sheet 115 has a function of reflecting the light leaked from the back surface 95B of the optical plate 95 and causing it to enter the optical plate 90 again. The reflective sheet 115 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 115 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 115 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

<< Other backlight devices >>
The backlight device incorporating the optical wavelength conversion sheet 10 may be a direct type backlight device as shown in FIG. The backlight device 130 shown in FIG. 15 includes a light source 90, an optical plate 131 that receives the light of the light source 90 and functions as a light diffusing plate, and an optical wavelength conversion sheet 10 arranged on the light emitting side of the optical plate 131. The lens sheet 100 arranged on the light emitting side of the optical wavelength conversion sheet 10, the lens sheet 105 arranged on the light emitting side of the lens sheet 100, and the reflective polarization separation sheet 110 arranged on the light emitting side of the lens sheet 105. I have. In the present embodiment, the light source 90 is arranged directly below the optical plate 131, not on the side of the optical plate 131. In FIG. 15, the members having the same reference numerals as those in FIG. 12 are the same as the members shown in FIG. 12, so the description thereof will be omitted. The backlight device 130 is not provided with the reflective sheet 115.

<Optical plate>
The optical plate 131 as a light diffusing plate has a quadrangular shape in a plan view. The optical plate 131 has an incoming light receiving surface 131A formed by one main surface on the light source 95 side and an outgoing light emitting surface 131B formed by the other main surface on the light wavelength conversion sheet 10. The light incident on the optical plate 131 from the light incoming surface 131A is diffused in the optical plate 131 and emitted from the light emitting surface 131B.

<< Other backlight devices >>
The backlight device 80 shown in FIG. 12 includes an optical wavelength conversion sheet 10, but the structure of the backlight device is not particularly limited as long as it includes an optical wavelength conversion member. For example, as shown in FIG. 16, the backlight device may be a backlight device 140 including a light source 150 instead of the light wavelength conversion sheet 10 and the light source 90. The light source 150 is a form of an optical wavelength conversion member, and as shown in FIG. 17, a substrate 151, a reflective member 152 having an opening 152A arranged on the substrate 151, and a reflective member 152 on the substrate 151 and on the substrate 151. It is provided with a light emitting body 153 such as a light emitting diode arranged in the opening 152A of the above, and an optical wavelength conversion unit 154 filled in the opening 152A of the reflecting member 152 so as to cover the light emitting body 153. The light wavelength conversion unit 154 is different from the light wavelength conversion layer 11 in shape and arrangement, and the configuration and physical properties of the light wavelength conversion unit 154 are the same as those of the light wavelength conversion layer 11. Therefore, the description thereof will be omitted here. And. The light wavelength conversion unit 154 can be formed by filling the opening 152A of the reflection member 152 with the light wavelength conversion composition and curing it. When the light source 150 having the light wavelength conversion unit 154 is used, the structure is not particularly limited as long as the light wavelength conversion unit 154 is arranged so as to cover the light emitting body 153.

<< Other backlight devices >>
The backlight device may be the backlight device 160 shown in FIG. Specifically, the backlight device 160 shown in FIG. 18 includes a light-transmitting capillary 170 arranged between the light source 90 and the optical plate 95 instead of the light wavelength conversion sheet 10. The capillary 170 is a form of an optical wavelength conversion member, and is provided on the light incoming surface 95C of the optical plate 95 as shown in FIG. The capillary 170 is arranged so that the longitudinal direction is along the arrangement direction of the light sources 90.

The capillary 170 has an optical wavelength conversion unit 171 enclosed in a tube 172 such as a glass tube. The light wavelength conversion unit 171 is different from the light wavelength conversion layer 11 only in the arrangement location and shape, and the configuration and physical properties of the light wavelength conversion unit 171 are the same as those of the light wavelength conversion layer 11. Therefore, the description thereof is omitted here. And. Further, since the light wavelength conversion unit 171 has excellent heat resistance and moisture heat resistance, it can be used without being covered with the tube 172. In particular, in the light wavelength conversion unit 171, when the coating layer 4 of the light wavelength conversion particles 1 is a barrier layer, the light wavelength conversion unit 171 is covered with a tube 172 because it has better heat resistance and moisture heat resistance. Can be used without.

According to the present embodiment, the resin particles 2 present in the light wavelength conversion layer 11 can suppress the deterioration of the quantum dots 3, so that the barriers are as shown in the light wavelength conversion sheets 10, 20, 30, 40, 50, and 60. The film can be omitted. As a result, the process of the optical wavelength conversion sheet can be simplified, so that the quality can be easily improved and the optical wavelength conversion sheet can be made thinner.

In an optical wavelength conversion sheet provided with a barrier film, when a heat resistance test or a moist heat resistance test is performed, punctate defects such as pinholes and cracks are likely to occur in the barrier film. When a defect portion is generated in the barrier film, moisture or oxygen may enter from the defect portion, and some quantum dots may be deteriorated to generate a point-like reduced brightness portion (luminance defect) in the optical wavelength conversion sheet. .. This punctate luminance defect is more easily visible than in the case where the quantum dots are deteriorated as a whole and the luminance is uniformly lowered. On the other hand, according to the present embodiment, the resin particles 11 existing in the light wavelength conversion layer 11 can suppress the deterioration of the quantum dots 3, so that even if the barrier films 61 and 62 have defects, the defects are generated. Even when water or oxygen enters from the defect portion, it is possible to suppress the point-shaped brightness defect.

According to the present embodiment, the resin particles 2 existing in the light wavelength conversion layer 11 can suppress the deterioration of the quantum dots 3, so that the peripheral portions 10C of the light wavelength conversion sheets 10, 20, 30, 40, 50, and 60 , 20A, 30A, 40A, 50A, 60C can also suppress the deterioration of the quantum dots 3.

In the optical wavelength conversion sheet 40, since the optical wavelength conversion layer 11 and the optical member 41 are integrated, the optical wavelength conversion sheet and the optical member are simplified and thin as compared with the case where the optical wavelength conversion sheet and the optical member are arranged separately and independently. A backlight device can be obtained. That is, when the light wavelength conversion sheet and the optical member are arranged separately and independently, since an air interface exists between the light wavelength conversion sheet and the optical member, a relatively large void is created in the backlight device. It takes. On the other hand, in the present embodiment, since the light wavelength conversion layer 11 and the optical member 41 are integrated, there is no air interface between the light wavelength conversion layer 11 and the optical member 41. This makes it possible to obtain a simplified thin backlight device.

A light emitting body such as a light emitting diode also emits heat when it emits light. Therefore, normally, when the light wavelength conversion unit is incorporated in the light source or when the light wavelength conversion member is arranged at a position close to the light source, the light wavelength conversion unit is covered in order to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, since the resin particles 11 existing in the light wavelength conversion unit 154 can improve the heat resistance and the moist heat resistance of the light wavelength conversion unit 154, the light wavelength conversion unit 154 is used as a barrier member. Deterioration of the quantum dots 3 can be suppressed without covering with. As a result, the light wavelength conversion unit 154 can be incorporated into the light source 150.

Conventionally, light that has been wavelength-converted by quantum dots emitted from the light wavelength conversion sheet is condensed on the light emitting side of the light wavelength conversion sheet, and light that has not been wavelength-converted by the light wavelength conversion sheet is collected by the light wavelength conversion sheet. It is being studied to improve the light wavelength conversion efficiency by arranging a lens sheet to be returned to the side. However, the optical wavelength conversion efficiency is not sufficient only by arranging such a lens sheet, and further improvement of the optical wavelength conversion efficiency is desired. According to the present embodiment, when the external haze value of the light wavelength conversion sheet 10 is smaller than the internal haze value of the light wavelength conversion sheet 10, the light wavelength conversion efficiency can be further improved. That is, since the light emitted from the light source has straightness, the light that enters the light wavelength conversion sheet and emits the light wavelength conversion sheet without being wavelength-converted by the quantum dots also has straightness. There is. Here, when the external haze value of the optical wavelength conversion sheet is high, the non-wavelength-converted light having straightness on the surface of the optical wavelength conversion sheet is refracted, and in the unconverted wavelength light emitted from the optical wavelength conversion sheet. Has a large number of components with a large emission angle. On the other hand, a lens sheet having a condensing function and a retroreflective function tends to retroreflect the lens sheet as the incident angle on the lens sheet is smaller. That is, the larger the angle of incidence on the lens sheet, the easier it is for the light to pass through the lens sheet. In the present embodiment, in the light wavelength conversion sheet 10, the external haze value is smaller than the internal haze value, so that even if the light that has not been wavelength-converted on the surface of the light wavelength conversion sheet 10 is refracted, it is emitted. It can be emitted in a state where the angle is small, and thus it is possible to increase the number of components having a small emission angle in the unwavelength-converted light emitted from the optical wavelength conversion sheet 10. Therefore, the lens sheet 100 can retroreflect the light emitted from the light wavelength conversion sheet without wavelength conversion and return it to the light wavelength conversion sheet 10 side, so that the opportunity for wavelength conversion increases. Further, since the internal haze value is larger than the external haze value, the optical path length is extended by scattering the light a plurality of times inside the optical wavelength conversion sheet, and the chance of wavelength conversion is further increased. Thereby, the light wavelength conversion efficiency can be improved. Since the quantum dots 3 emit light isotropically, the light wavelength-converted by the quantum dots 3 is oriented in various directions, and when the light reaches the surface of the optical wavelength conversion sheet 10, the surface of the optical wavelength conversion sheet is further reached. The light is refracted at, and the wavelength-converted light becomes light having a large angle and is easily emitted from the light wavelength conversion sheet. Therefore, the wavelength-converted light is relatively easy to pass through the lens sheet 100.

In the above, the light diffusion characteristic (external diffusion characteristic) on the surface of the light wavelength conversion sheet is expressed by using the external haze value for the following reasons. First, the light diffusion characteristics of the light wavelength conversion sheet can be evaluated by measuring the light intensity of the transmitted light for each angle with a known variable luminosity meter such as a goniophotometer. It is extremely difficult to define the light diffusion characteristics of the light wavelength conversion sheet using the result of light intensity. On the other hand, as described above, in the definition of haze, transmitted light deviated by 2.5 ° or more with respect to incident light is measured as haze, but transmitted light less than 2.5 ° with respect to incident light is measured as haze. Not measured. As described above, the transmitted light having a haze of less than 2.5 ° with respect to the incident light is not measured, but as described above, the light having a large incident angle to the lens sheet, that is, the transmitted light having a large emission angle in the optical wavelength conversion sheet is emitted. Since it is a problem, it is important how much transmitted light exists that deviates by 2.5 ° or more from the transmitted light that is less than 2.5 ° with respect to the incident light. Therefore, the light diffusion characteristic of the light wavelength conversion sheet can be expressed by the magnitude of the haze value of the light wavelength conversion sheet without measuring the light intensity for each angle of transmitted light by the angle-changing photometer. On the other hand, it is necessary to consider that the light is refracted on the surface of the light wavelength conversion sheet and the emission angle becomes large. Therefore, in order to express the light diffusion characteristics on the surface of the light wavelength conversion sheet, an external haze is required. The value was used.

According to the present embodiment, since the light wavelength conversion layer 11 contains the light scattering particles 17, the light wavelength conversion efficiency can be further improved. Therefore, for example, a light source that emits blue light is used as the light source 90, a quantum dot that converts blue light into green light is used as the first quantum dot 3A, and blue light is converted into red light as the second quantum dot 3B. When a light wavelength conversion sheet containing quantum dots is irradiated with blue light, the chromaticity x and y can be increased as compared with the light wavelength conversion sheet not containing light-scattering particles, and the color is white light or a color close to white. You can get the light of taste.

According to the present embodiment, since the light wavelength conversion layer 11 contains the light scattering particles 17, the green light emission can be preferentially enhanced over the red light emission. The reason for this is not clear, but light-scattering particles may impede energy transfer from the first quantum dot that converts blue light to green light to the second quantum dot that converts blue light to red light. It is considered that this is because the green light emission, which was originally deactivated by the above energy transfer, reaches the light emission process without being deactivated, and as a result, the green light emission increases.

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

<< Manufacture of light wavelength conversion particles >>
Light wavelength conversion particles were obtained according to the following procedure.
<Example 1>
(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 15 were also determined to be the same as those of the light wavelength conversion particles 1.

<Example 2>
(Light wavelength conversion particle 2)
In order to form a coating layer on the surface of the light wavelength conversion particles 1, 30 parts by mass of tricyclodecanedimethanol diacrylate (product name "A-DCP", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) and a thermal radical polymerization initiator (2). , 2'-azobis (2,4-dimethylvaleronitrile), manufactured by Tokyo Chemical Industry Co., Ltd.) A coating layer composition 1 containing 0.3 parts by mass was added to the reaction solution before suction filtration of Example 1 to add a coating layer. The temperature of this reaction solution containing the composition 1 was raised to 50 ° C., and suspension polymerization was carried out over 3 hours while the temperature of the reaction solution was 50 ° C. Then, in order to completely inactivate the thermal radical initiator, the temperature of the reaction solution is raised to 80 ° C., and the reaction solution is stirred at 80 ° C. for 3 hours to form a coating layer on the surface. A particulate polymer was obtained. Then, the reaction solution containing the polymer in the polymerization vessel was cooled to room temperature while stirring with a stirrer. Next, the reaction solution was suction-filtered, and the filtration residue was washed with ion-exchanged water and then deliquesed to obtain light wavelength-converted particles 2. In the light wavelength conversion particles 2, green emission quantum dots and red emission quantum dots were included in the resin particles, and the average particle diameter of the light wavelength conversion particles 2 was 3.3 μm.

<Example 3>
(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 fact that the composition 2 for light wavelength conversion particles consisting of 1 part by mass and 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. , The light wavelength conversion particle 3 was obtained by the same procedure as that of the light wavelength conversion particle 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.

<Example 4>
(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.

<Example 5>
(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.

<Example 6>
(Light wavelength conversion particle 6)
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.), 2-metacloyloxyethyl acid phosphate (product name) "Light ester P-2M", manufactured by Kyoeisha 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 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 5 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 6 were obtained by the same procedure as for conversion particles 1. 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.

<Example 7>
(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.

<Example 8>
(Light wavelength conversion particle 8)
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.), stearylamine (product name "Farmin 80", Kao) 10 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 7 for light wavelength conversion particles consisting of 1 part by mass was used. 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.

<Example 9>
(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.

<Example 10>
(Light wavelength conversion particle 10)
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.), ω-carboxy-polycaprolactone mono (meth) acrylate (Product name "M-5300", manufactured by Toa Synthetic Co., Ltd.) 10 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.

<Example 11>
(Light wavelength conversion particle 11)
The composition 1 for light wavelength conversion particles is put into a polymerization vessel, dried at 80 ° C., and then irradiated with ultraviolet rays to the composition 1 for light wavelength conversion particles so that the integrated light amount is 500 mJ / cm ^2. The composition 1 for light wavelength conversion particles was cured to obtain a cured product of the composition 1 for light wavelength conversion particles. Then, this cured product was pulverized using a bead mill device in which zirconia beads having a bead diameter of 500 μm were placed in a stirring container to obtain light wavelength conversion particles 11. In the light wavelength conversion particles 11, 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 1 was 11 μm.

<Example 12>
(Light wavelength conversion particle 12)
The light wavelength conversion particles 12 were obtained by the same procedure as the light wavelength conversion particles 11 except that the composition 5 for light wavelength conversion particles was used instead of the composition 1 for light wavelength conversion particles. 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 13 μm.

<Example 13>
(Light wavelength conversion particle 13)
The light wavelength conversion particles 13 were obtained by the same procedure as the light wavelength conversion particles 11 except that the composition 7 for light wavelength conversion particles was used instead of the composition 1 for light wavelength conversion particles. In the light wavelength conversion particles 13, 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 13 was 11 μm.

<Example 14>
(Light wavelength conversion particle 14)
The light wavelength conversion particles 14 were obtained by the same procedure as the light wavelength conversion particles 11 except that the composition 9 for light wavelength conversion particles was used instead of the composition 1 for light wavelength conversion particles. In the light wavelength conversion particles 14, 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 14 was 14 μm.

<Example 15>
(Light wavelength conversion particle 15)
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 15. 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 15 in which the surface of the resin particles of the light wavelength conversion particles 1 was covered with a silica glass layer having a thickness of 50 nm were obtained. The average particle size of the light wavelength conversion particles 15 was 3.1 μm.

<Example 16>
(Light wavelength conversion particle 16)
The surface of the resin particles of the light wavelength conversion particles 5 was covered with a silica glass layer having a thickness of 50 nm in the same manner as in Example 15 except that the light wavelength conversion particles 5 were used instead of the light wavelength conversion particles 1. Light wavelength conversion particles 16 were obtained. The average particle size of the light wavelength conversion particles 16 was 3.1 μm.

<Example 17>
(Light wavelength conversion particle 17)
The surface of the resin particles of the light wavelength conversion particles 7 was covered with a silica glass layer having a thickness of 50 nm in the same manner as in Example 15 except that the light wavelength conversion particles 7 were used instead of the light wavelength conversion particles 1. Light wavelength conversion particles 17 were obtained. The average particle size of the light wavelength conversion particles 17 was 3.1 μm.

<Example 18>
(Light wavelength conversion particle 18)
The surface of the resin particles of the light wavelength conversion particles 9 was covered with a silica glass layer having a thickness of 50 nm in the same manner as in Example 15 except that the light wavelength conversion particles 9 were used instead of the light wavelength conversion particles 1. Light wavelength conversion particles 18 were obtained. The average particle size of the light wavelength conversion particles 18 was 3.1 μm.

<Comparative example 1>
(Light wavelength conversion particle 19)
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 19 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 19, 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 19 was 12 μm.

<< Adjustment of optical wavelength conversion composition >>
Each component was blended so as to have the composition shown below to obtain an optical wavelength conversion composition.
<Example 19>
(Light wavelength conversion composition 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

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

<Example 21>
(Light wavelength conversion composition 3)
-Light wavelength conversion particles 2: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

<Example 22>
(Light wavelength conversion composition 4)
-Light wavelength conversion particles 3: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure (" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

<Example 23>
(Light wavelength conversion composition 5)
-Light wavelength conversion particles 4: 20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacure" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

<Example 24>
(Light wavelength conversion composition 6)
-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

<Example 25>
(Light wavelength conversion composition 7)
-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

<Example 26>
(Light wavelength conversion composition 8)
-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

<Example 27>
(Light wavelength conversion composition 9)
-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

<Example 28>
(Light wavelength conversion composition 10)
-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

<Example 29>
(Light wavelength conversion composition 11)
-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

<Example 30>
(Light wavelength conversion composition 12)
-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

<Example 31>
(Light wavelength conversion composition 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 32>
(Light wavelength conversion composition 14)
-Light wavelength conversion particles 13:20 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 33>
(Light wavelength conversion composition 15)
-Light wavelength conversion particles 14:20 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

<Example 34>
(Light wavelength conversion composition 16)
-Light wavelength conversion particles 15:20 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

<Example 35>
(Light wavelength conversion composition 17)
16 parts by mass of light wavelength conversion particles ・ 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 36>
(Light wavelength conversion composition 18)
-Light wavelength conversion particles 17:20 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

<Example 37>
(Light wavelength conversion composition 19)
-Light wavelength conversion particles 18:20 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

<Comparative example 2>
(Light wavelength conversion composition 20)
-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

<Comparative example 3>
(Light wavelength conversion composition 21)
-Light wavelength conversion particles 19:20 parts by mass-Epoxy acrylate (product name "Unidic V-5500", manufactured by DIC): 80 parts by mass-Radical polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Irgacare" Registered trademark) 184 ”, manufactured by BASF Japan Ltd.): 1 part by mass

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

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

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

<Example 38>
The composition for the light diffusion layer is applied to one side of two polyethylene terephthalate (PET) base materials (product name "Lumilar T60", manufactured by Toray Industries, Inc.) as a light transmissive base material having a size of 7 inches and a thickness of 50 μm. , Applied to form a coating film. Next, the solvent in the coating film was evaporated by passing dry air at 80 ° C. for 30 seconds to dry the formed coating film. Then, ultraviolet rays were irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to form a light diffusing layer having a film thickness of 10 μm, and a PET substrate with a light diffusing layer was formed.

Next, the light wavelength conversion composition 1 was applied to a surface of the PET substrate with a light diffusion layer opposite to the surface on the light diffusion layer side and dried at 80 ° C. to form a coating film. Then, the other PET substrate with a light diffusing layer was laminated on the coating film so that the surface of the PET substrate with a light diffusing layer on the other side opposite to the surface on the light diffusing layer side was in contact with the coating film. In this state, ultraviolet rays are irradiated so that the integrated light amount is 500 mJ / cm ² , and the coating film is cured to form an optical wavelength conversion layer having a film thickness of 100 μm, and the optical wavelength conversion layer and two sheets of light are formed. It was integrated with a PET substrate with a diffusion layer. As a result, the optical wavelength conversion sheet according to Example 38 was obtained.

<Examples 39 to 56 and Comparative Examples 4 and 5>
In Examples 39 to 56 and Comparative Examples 4 and 5, light was used in the same manner as in Example 38, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. A wavelength conversion sheet was prepared.

<Example 57>
The light wavelength conversion composition 1 was applied to one surface of a 50 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) and dried at 80 ° C. to form a coating film. .. Then, the coating film was cured by irradiating with ultraviolet rays so that the integrated light intensity was 500 mJ / cm ^2. Finally, the PET substrate was peeled off to obtain an optical wavelength conversion sheet comprising only an optical wavelength conversion layer having a film thickness of 100 μm according to Example 57.

<Example 58 and Comparative Examples 6 and 7>
In Example 58 and Comparative Examples 6 and 7, light wavelength conversion was performed in the same manner as in Example 57, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. A sheet was prepared.

<Example 59>
The composition 1 for the overcoat layer was applied to one surface of the light wavelength conversion sheet (light wavelength conversion layer) produced in Example 57 to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. Next, in the same manner, the composition 1 for the overcoat layer was applied to the other surface of the light wavelength conversion layer to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light intensity was 500 mJ / cm ² , and the coating film was cured to obtain an overcoat layer having a film thickness of 5 μm. As a result, an optical wavelength conversion sheet composed of an optical wavelength conversion layer and an overcoat layer formed on both sides of the optical wavelength conversion layer was obtained.

<Example 60>
In Example 60, an optical wavelength conversion sheet was produced in the same manner as in Example 59, except that the composition 2 for the overcoat layer was used instead of the composition 1 for the overcoat layer.

<Example 61 and Comparative Examples 8 and 9>
In Example 61 and Comparative Examples 8 and 9, light wavelength conversion was performed in the same manner as in Example 59, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. A sheet was prepared.

<Example 62>
A prism layer composition containing urethane acrylate is uniformly applied to one surface of a 100 μm-thick polyethylene terephthalate (PET) base material (product name “Lumilar T60”, manufactured by Toray Industries, Inc.) to form a prism layer composition. A coating film was formed to form a laminate for a prism sheet. Then, the traveling speed of the prism sheet laminate is such that the coating film of the lens layer composition is on the molding mold side in the rotating molding mold having recesses having a shape opposite to the desired unit prism shape. The shape of the unit prism is formed on the coating film of the prism layer composition by supplying at 20 m / min with a molding die, and light such as ultraviolet rays is applied to the coating film of the prism layer composition via the PET substrate. Irradiation was performed to cure the coating film of the composition for the prism layer. Finally, the cured coating film of the prism layer composition was peeled off from the molding mold together with the PET base material to obtain a prism sheet having a prism layer formed on one surface of the PET base material. The prism layers are arranged side by side on the sheet-shaped main body and each of them extends in a direction intersecting the arrangement direction, the apex angle is 90 °, the width is 47 μm, and the height is high. It had a plurality of triangular columnar unit prisms having a height of 30 μm.

Next, the light wavelength conversion composition 1 was applied to the surface of the prism sheet opposite to the surface of the PET substrate on the prism layer side and dried at 80 ° C. to form a coating film. Then, by irradiating the coating film with ultraviolet rays so that the integrated light amount becomes 500 mJ / cm ² , a light wavelength conversion layer having a film thickness of 100 μm integrated with the prism sheet was formed. As a result, the optical wavelength conversion sheet according to Example 62 was obtained.

<Example 63 and Comparative Examples 10 and 11>
In Example 63 and Comparative Examples 10 and 11, light wavelength conversion was performed in the same manner as in Example 62, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. A sheet was prepared.

<Example 64>
First, two barrier films were prepared by the following method. In a high-frequency sputtering apparatus, polyethylene terephthalate as a light-transmitting substrate having a size of 7 inches and a thickness of 50 μm is generated by applying a high-frequency power of 13.56 MHz and a power of 5 kW to the electrodes to generate an electric discharge in the chamber. A silica-deposited layer made of a target substance (silica), having a thickness of 50 nm and a refractive index of 1.46, was formed on one side of a (PET) base material (product name “Lumilar T60”, manufactured by Toray Co., Ltd.). As a result, two barrier films having a silica-deposited layer formed on one surface of the PET base material were formed.

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

Next, the light wavelength conversion composition 1 was applied to the silica-deposited layer side of one of the barrier films with a light diffusion layer and dried at 80 ° C. to form a coating film. Then, the other barrier film with a light diffusion layer was laminated on the surface of the silica-deposited layer of the barrier film with a light diffusion layer in the coating film so that the silica vapor deposition layer was in contact with the surface. In this state, by irradiating the coating film with ultraviolet rays so that the integrated light amount is 500 mJ / cm ² , a light wavelength conversion layer having a thickness of 100 μm is formed in close contact with both barrier films with light diffusion layers. did. As a result, the optical wavelength conversion sheet according to Example 64 was obtained.

<Example 65 and Comparative Examples 12 and 13>
In Example 65 and Comparative Examples 12 and 13, light wavelength conversion was performed in the same manner as in Example 64, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. A sheet was prepared.

<Example 66>
The light wavelength conversion composition 1 was filled in the opening of the reflection member of the blue light emitting diode having an emission peak wavelength of 450 nm, and dried at 80 ° C. Then, the light source according to the 66th embodiment is provided with an optical wavelength conversion unit filled in the opening of the reflection member of the blue light emitting diode by irradiating ultraviolet rays so that the integrated light amount becomes 500 mJ / cm ^{2 to cure the filler.} Got

<Example 67 and Comparative Examples 14 and 15>
In Example 67 and Comparative Examples 14 and 15, a light source was produced in the same manner as in Example 66, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1. did.

<Example 68>
A glass tube having a length of 12 mm was filled with the light wavelength conversion composition 1. Then, after closing the end portion of the glass tube, ultraviolet rays are ^{irradiated so that the integrated light amount becomes 500 mJ / cm 2} , the filling material is cured, and the light wavelength conversion unit is enclosed in the glass tube. Obtained a capillary related to.

<Example 69>
The light wavelength conversion composition 16 was applied to the light entering surface of the light guide plate of the backlight device of the Kindle Fire (registered trademark) HDX7 described later to form a coating film. Then, ultraviolet rays were irradiated so that the integrated light amount was 500 mJ / cm ² , and the coating film was cured to obtain an optical wavelength conversion layer according to Example 69 formed on the light entry surface of the light guide plate.

<Comparative Examples 16 and 17>
In Comparative Examples 16 and 17, capillaries were prepared in the same manner as in Example 68, except that each light wavelength conversion composition shown in Table 2 was used instead of the light wavelength conversion composition 1.

<Confirmation of specific elements and carboxylic acids in resin particles>
In the light wavelength conversion particles 1 to 19 according to Examples 1 to 18 and Comparative Example 1, it was confirmed whether or not the above-mentioned specific element or carboxylic acid was detected from the resin particles. Specifically, for the optical wavelength conversion particles 1 to 8, 11 to 13 and 15, the energy dispersive X-ray analyzer (product name "JEM-2800" ( ^{equipped with 100 mm 2} silicon drift detector (SDD)), Japan Using JEOL Ltd.), under the conditions of an acceleration voltage of 100 kV and a measurement time of 30 seconds, sulfur element, phosphorus element, at any 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. And whether at least one of the nitrogen elements was detected. For the light wavelength conversion particles 9, 10 and 14, an infrared microscope (product name "Nicolet iN10", manufactured by Thermo Fisher Scientific Co., Ltd.) 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, 11 to 13, 15 to 17, 19 the content of a specific element contained in the light wavelength conversion particles is determined by a fluorescent X-ray analyzer (product name "EDX-800HS"). Measured using 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 sheets according to Examples 38 to 65 and Comparative Examples 4 to 13, respectively. The water vapor transmittance of the optical wavelength conversion sheet is 40 ° C. and 90% relative humidity using a water vapor transmittance measuring device (product name "PERMATRAN-W3 / 31", manufactured by MOCON) in accordance with JIS K7129: 2008. It was measured under the conditions of. The oxygen transmittance of the optical wavelength conversion sheet is 23 ° C. relative to the oxygen gas transmittance measuring device (product name "OX-TRAN 2/21", manufactured by MOCON) in accordance with JIS K7126: 2006. It was measured under the condition of 90% humidity. The water vapor permeability and the oxygen permeability were taken as the average value of the values obtained by measuring each of the three times.

<Measurement of brightness maintenance rate after heat resistance test>
In the light wavelength conversion sheet, the light source, the capillary, and the light wavelength conversion layer according to the above Examples and Comparative Examples, the heat resistance of the light wavelength conversion sheet, the light source, the capillary, and the light wavelength conversion layer to be left in an environment of 80 ° C. for 500 hours. The test was carried out, and the maintenance rate of the brightness after the heat resistance test with respect to the brightness before the heat resistance test in the light wavelength conversion sheet, the light source, the capillary and the light wavelength conversion layer was investigated. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and the optical wavelength conversion sheet before the heat resistance test was incorporated into this backlight device. 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.

In Examples 38 to 61, 64, 65 and Comparative Examples 4 to 9, 12, and 13, the light guide plate is arranged so that the blue light emitting diode side is the light entrance surface, and the light guide plate is on the light emission surface of the light guide plate. A backlight device was obtained by arranging the light wavelength conversion sheet, the first prism sheet, and the second prism sheet according to ~ 61, 64, 65 and Comparative Examples 4 to 9, 12, 13 in this order. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the first prism sheet.

In Examples 62 and 63 and Comparative Examples 10 and 11, the light guide plate is arranged so that the blue light emitting diode side is the light entrance surface, and the prism surface of the prism sheet is the light emission side on the light emission surface of the light guide plate. The light wavelength conversion sheet and the second prism sheet according to Examples 62 and 63 and Comparative Examples 10 and 11 were arranged in this order to obtain a backlight device. The second prism sheet was arranged so that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the prism sheets in the optical wavelength conversion sheets according to Examples 62 and 63 and Comparative Examples 10 and 11. In this way, a backlight device incorporating the optical wavelength conversion sheets according to Examples 62 and 63 and Comparative Examples 10 and 11 was obtained.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated on one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface of the backlight device in the thickness direction of the backlight device. , Manufactured by Konica Minolta Co., Ltd.) under the condition of a measurement angle of 1 °.

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

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

In Examples 66 and 67 and Comparative Examples 14 and 15, the retention rate of the brightness after the heat resistance test was determined with respect to the brightness before the heat resistance test in the same manner as described above. However, in Examples 66 and 67 and Comparative Examples 14 and 15, the heat resistance test was performed on the light source, and the blue light emitting diode was replaced with the light source according to Examples 66 and 67 and Comparative Examples 14 and 15 to be a light source. A backlight device was used in which the light guide plate was arranged so that the side was the light source surface, and the first prism sheet and the second prism sheet were arranged in this order on the light source surface of the light source plate.

In Examples 68 and 69 and Comparative Examples 16 and 17, the retention rate of the brightness after the heat resistance test was determined with respect to the brightness before the heat resistance test in the same manner as described above. However, in Example 68 and Comparative Examples 16 and 17, the heat resistance test was performed on the capillary, the light guide plate was arranged so that the blue light emitting diode side was the light entering surface, and the blue light emitting diode and the light guide plate were arranged. A backlight device in which the capillarys according to the 68th embodiment and the 16th and 17th comparative examples are arranged between the incoming surface and the light emitting surface, and the first prism sheet and the second prism sheet are arranged in this order on the light emitting surface of the light guide plate. Was used. Further, in Example 69, the heat resistance test of the light wavelength conversion layer according to Example 69 formed on the light entry surface of the light guide plate is performed together with the light guide plate, and the blue light emitting diode side becomes the light wavelength conversion layer. As described above, a backlight device was used in which the light guide plate was arranged and the first prism sheet and the second prism sheet were arranged in this order on the light emitting surface of the light guide plate.

<Measurement of brightness maintenance rate after moisture resistance test>
In the light wavelength conversion sheet, the light source, the capillary and the light wavelength conversion layer according to the above Examples and Comparative Examples, the light wavelength conversion sheet, the light source, the capillary and the light wavelength conversion layer are placed at 60 ° C. and the relative humidity is 90% for 500 hours. A moist heat resistance test was conducted to examine the retention rate of the brightness after the moist heat resistance test with respect to the brightness before the moist heat resistance test in the light wavelength conversion sheet, the light source, the capillary and the light wavelength conversion layer. Specifically, first, a Kindle Fire (registered trademark) HDX7 backlight device was prepared, and an optical wavelength conversion sheet before the moisture resistance test was incorporated into this backlight device in the same manner as in the above heat resistance test.

Then, the blue light emitting diode of the backlight device incorporating the light wavelength conversion sheet is turned on, blue light is irradiated on one surface of the light wavelength conversion sheet, and the backlight device is passed through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from the light emitting surface (the surface of the second prism sheet) is measured at a position 400 mm away from the light emitting surface of the backlight device in the thickness direction of the backlight device. , Manufactured by Konica Minolta Co., Ltd.) under the condition of a measurement angle of 1 °.

Next, the light wavelength conversion sheet before the moisture heat resistance test is removed from the backlight device, and the light wavelength conversion sheet is subjected to a heat resistance test in which the light wavelength conversion sheet is left in an environment of 60 ° C. and 90% relative humidity for 500 hours. It was. Then, the light wavelength conversion sheet after the moisture resistance test was incorporated into the backlight device in the same manner as described above. In this state, in the same manner as described above, one surface of the light wavelength conversion sheet is irradiated with blue light, and the light emitting surface of the backlight device (the surface of the second prism sheet) passes through the other surface of the light wavelength conversion sheet. ) 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 radiance meter (product name "CS2000", manufactured by Konica Minolta). The measurement was performed under the condition of an angle of 1 °.

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

In Examples 66 and 67 and Comparative Examples 14 and 15, the retention rate of the brightness after the moisture resistance test was determined with respect to the brightness before the moisture resistance test in the same manner as described above. However, in Examples 66 and 67 and Comparative Examples 14 and 15, the moisture resistance test was performed on the light source, and the blue light emitting diode was replaced with the light source according to Examples 66 and 67 and Comparative Examples 14 and 15 to be a light source. A backlight device was used in which the light guide plate was arranged so that the side was the light source surface, and the first prism sheet and the second prism sheet were arranged in this order on the light source surface of the light source plate.

In Examples 68 and 69 and Comparative Examples 16 and 17, the retention rate of the brightness after the moisture resistance test was determined with respect to the brightness before the moisture resistance test in the same manner as described above. However, in Example 68 and Comparative Examples 16 and 17, the moisture resistance test was performed on the capillary, the light guide plate was arranged so that the blue light emitting diode side was the light input surface, and the blue light emitting diode and the light guide plate were arranged. A backlight device in which the capillarys according to the 68th embodiment and the 16th and 17th comparative examples are arranged between the incoming surface and the light emitting surface, and the first prism sheet and the second prism sheet are arranged in this order on the light emitting surface of the light guide plate. Was used. Further, in Example 69, the heat resistance test of the light wavelength conversion layer according to Example 69 formed on the light entry surface of the light guide plate is performed together with the light guide plate, and the blue light emitting diode side becomes the light wavelength conversion layer. As described above, a backlight device was used in which the light guide plate was arranged and the first prism sheet and the second prism sheet were arranged in this order on the light emitting surface of the light guide plate.

<Evaluation of point-shaped brightness defects>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 38 to 65 and Comparative Examples 4 to 13, there is a point-like luminance defect on the light emitting surface at the time of light emission in the backlight device. The presence was visually observed and evaluated. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture-heat resistance test according to Examples 38 to 65 and Comparative Examples 4 to 13, similarly, a point is formed on the light emitting surface at the time of light emission in the backlight device. It was visually observed and evaluated whether or not there was a defect in the brightness of the shape. The evaluation criteria are as follows.
◯: No point-shaped brightness defect was confirmed.
Δ: Several point-shaped luminance defects were confirmed.
X: Many point-shaped luminance defects were confirmed.

<Measurement of deterioration width of the peripheral edge of the optical wavelength conversion sheet>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to Examples 38 to 65 and Comparative Examples 4 to 13, the brightness distribution on the light emitting surface at the time of light emission in the backlight device is determined by the light wavelength. The measurement was performed from the thickness direction of the conversion sheet using a 2D color luminance meter (product name "UA-200", manufactured by Topcon Techno House Co., Ltd.). Then, from the measured brightness distribution of the light emitting surface, the position of the light emitting surface (luminance 80% position) at which the brightness is 80% with respect to the brightness of the central portion of the light emitting surface is obtained, and is closest to the brightness 80% position on the light emitting surface. The shortest distance from the edge to the position where the brightness is 80% was obtained. Then, the shortest distance was randomly obtained for 20 places, and the average value of the shortest distances at these 20 places was taken as the deterioration width of the peripheral portion of the optical wavelength conversion sheet. Further, using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the moisture resistance test according to Examples 38 to 65 and Comparative Examples 4 to 13, the brightness distribution of the light emitting surface is measured in the same manner to emit light. Find the position of the light emitting surface (luminance 80% position) where the brightness is 80% of the brightness of the central part of the surface, and find the shortest distance from the end closest to the brightness 80% position on the light emitting surface to the brightness 80% position. It was.

The results are shown in Tables 1 to 5 below.

The results will be described below. As can be seen from Tables 3 to 5, in the light wavelength conversion sheets according to Examples 38 to 63, Quantum Dots are included in the resin particles containing at least one of a specific element and a carboxylic acid. Since the light wavelength conversion particles 1 to 18 according to 18 are used, the light wavelength conversion sheets and the resin particles containing quantum dots according to Comparative Examples 4, 6, 8 and 10 which do not use the resin particles themselves are used. However, the brightness retention rate after the heat resistance test and the moist heat resistance test is higher than that of the light wavelength conversion sheets according to Comparative Examples 5, 7, 9, and 11 in which the resin particles do not contain any specific element or carboxylic acid. Was expensive. Further, in the light wavelength conversion sheets according to Examples 53 to 56, 58, 61, 63, the resin particles are covered with the silica glass layer, and therefore the resin particles corresponding to each of these examples are covered with the silica glass layer. The brightness retention rate after the heat resistance test and the moisture heat resistance test was higher than that of the light wavelength conversion sheets according to Examples 38 to 52, 57, 59, 60, 62.

In the optical wavelength conversion sheet according to Examples 64 and 65, the optical wavelength conversion particles 1 and 15 according to Examples 1 and 15 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid. The light wavelength conversion sheet and the resin particles containing the quantum dots according to Comparative Example 12 which do not use the resin particles themselves are used, but the resin particles do not contain any specific element or carboxylic acid. Compared with the light wavelength conversion sheet according to Comparative Example 13, the brightness retention rate after the heat resistance test and the moisture heat resistance test was higher. Further, in the light wavelength conversion sheet according to Example 65, since the resin particles are covered with the silica glass layer, the heat resistance test is compared with the light wavelength conversion sheet according to Example 64 in which the resin particles are not covered with the silica glass layer. The brightness retention rate was high after and after the moisture resistance test.

In the light source according to Examples 66 and 67, the light wavelength conversion particles 1 and 15 according to Examples 1 and 15 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid are used. Therefore, the light source according to Comparative Example 14 in which the resin particles themselves are not used and the light source according to Comparative Example 15 in which the resin particles containing quantum dots are used, but the resin particles do not contain any specific element or carboxylic acid. The brightness retention rate after the heat resistance test and the moisture heat resistance test was higher than that of the above. Further, since the light source according to Example 67 has the resin particles covered with the silica glass layer, after the heat resistance test and the moisture heat resistance test as compared with the light source according to Example 66 in which the resin particles are not covered with the silica glass layer. The brightness maintenance rate was high.

In the capillary according to Example 68, since the light wavelength conversion particles 1 according to Example 1 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid are used, the resin particles themselves. Although the capillary and the resin particles containing the quantum dots according to Comparative Example 16 which do not use the above are used, the heat resistance is higher than that of the capillary according to Comparative Example 17 in which the resin particles do not contain any specific element or carboxylic acid. The brightness retention rate was high after the test and after the moisture resistance test. Since the light wavelength conversion layer according to Example 69 covers the resin particles with a silica glass layer, after the heat resistance test and the moist heat resistance test equivalent to those of Example 68 without enclosing the light wavelength conversion particles in a glass tube. Achieved the brightness maintenance rate of.

These mean that the light wavelength conversion particles 1 to 18 according to Examples 1 to 18 have high heat resistance and moisture heat resistance, and that at least one of a specific element and a carboxylic acid can suppress deterioration of quantum dots. There is. Further, the light wavelength conversion particles 15 to 18 mean that the deterioration of the quantum dots can be further suppressed as compared with the light wavelength conversion particles 1 to 14.

Since the barrier film was not used in the light wavelength conversion sheets according to Examples 28 to 63 and Comparative Examples 4 to 11, no punctate luminance defect was confirmed. Further, although the barrier film is used in the optical wavelength conversion sheets according to Examples 64 and 65, Quantum Dots are included in the resin particles containing at least one of a specific element and a carboxylic acid. Since the light wavelength conversion particles 1 and 15 according to No. 15 are used, no point-like luminance defect was confirmed. On the other hand, a comparison in which the optical wavelength conversion sheet according to Comparative Example 12 in which the resin particles themselves are not used and the resin particles containing quantum dots are used, but the resin particles do not contain any specific element or carboxylic acid. In the light wavelength conversion sheet according to Example 13, point-shaped luminance defects were confirmed. This means that at least one of the specific element and the carboxylic acid in the resin particles can suppress the deterioration of the quantum dots.

In the light wavelength conversion sheet according to Examples 38 to 65, the light wavelength conversion particles 1 to 18 according to Examples 1 to 18 in which quantum dots are contained in resin particles containing at least one of a specific element and a carboxylic acid. Therefore, the deterioration of the peripheral portion was suppressed. On the other hand, the optical wavelength conversion sheets according to Comparative Examples 4, 6, 8 and 10 in which the resin particles themselves are not used and the resin particles containing the quantum dots are used, but the resin particles are specific elements and carboxylic acids. In the optical wavelength conversion sheets according to Comparative Examples 5, 7, 9, and 11 containing no acid, deterioration of the peripheral portion was confirmed. This means that even in an environment where quantum dots are exposed to a large amount of oxygen or water vapor, such as at the periphery, at least one of a specific element and a carboxylic acid in the resin particles can suppress the deterioration of the quantum dots. There is. Further, in the optical wavelength conversion sheets according to Comparative Examples 12 and 13, the deterioration of the central portion was relatively suppressed by the barrier film, but the deterioration of the peripheral portion was not suppressed.

The total haze value of the light wavelength conversion sheet according to Example 38 was 98.9%, the internal haze value was 96.7%, and the external haze value was 2.2%. The haze value was 99.3%, the internal haze value was 99.3%, and the external haze value was 0%. Since the external haze value is smaller than the internal haze value in both light wavelength conversion sheets, the brightness is high regardless of before and after the heat resistance test and before and after the moisture heat resistance test, but the light wavelength according to Example 38. Comparing the conversion sheet and the light wavelength conversion sheet according to Example 39, the light wavelength conversion sheet according to Example 39 had higher brightness regardless of before and after the heat resistance test. This is because the light wavelength conversion sheet according to Example 39 contains alumina particles as light scattering particles, so that the internal haze value of the light wavelength conversion sheet according to Example 31 is that of the wavelength conversion sheet according to Example 38. This is because the haze value is larger than the internal haze value, which makes the external haze value smaller. Therefore, it was confirmed that the external haze value can be made smaller by including the light scattering particles in the light wavelength conversion sheet to further increase the internal haze value, and thereby the light wavelength conversion efficiency can be further improved. .. The total haze value, the internal haze value, and the haze value in the optical wavelength conversion sheet were measured as follows. First, using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute), the total haze value of the optical wavelength conversion sheet was measured according to JIS K7136. After that, a triacetyl cellulose base material having a thickness of 60 μm (product name “Panaclean PD-S1”, manufactured by Panadium Co., Ltd.) is interposed on both sides of the optical wavelength conversion sheet via a transparent optical adhesive layer having a thickness of 25 μm (product name “Panaclean PD-S1”). TD60UL ", manufactured by Fujifilm Co., Ltd.) was pasted. As a result, the uneven shape of the surface of the light wavelength conversion sheet was crushed, and the surface of the light wavelength conversion sheet became flat. In this state, the haze value was measured according to JIS K7136 using a haze meter (product name "HM-150", manufactured by Murakami Color Technology Research Institute) to obtain the internal haze value. Then, the external haze value was obtained by subtracting the internal haze value from the total haze value. The transparent optical adhesive layer and the triacetyl cellulose base material may also affect the internal haze value and the external haze value of the optical wavelength conversion sheet, but when the internal scattering of the optical wavelength conversion sheet is extremely large, these may affect the internal haze value and the external haze value. The effect on the internal haze value and the external haze value is extremely small and can be ignored. Further, when the internal scattering of the light wavelength conversion sheet is extremely large, the internal haze value may be the same as the total haze value, so that the external haze value may be 0%.

Further, in the optical wavelength conversion sheets according to Examples 59 and 60, a scratch test was performed on the overcoat layer, and the normal force and the horizontal force at that time were measured. As a result, the optical wavelength conversion sheet according to Example 59 was found. The normal force was 21 μN and the horizontal force was -11 μN, and the optical wavelength conversion sheet according to Example 60 had a normal force of 11 μN and a horizontal force of -6 μN. These overcoat layers became dense films and had an ability to prevent the light wavelength conversion layer from exposure to the atmosphere. However, in terms of the ability to prevent the light wavelength conversion layer from exposure to the atmosphere, the light wavelength conversion sheet according to Example 59. It can be said that the overcoat layer is higher than the overcoat layer of the optical wavelength conversion sheet according to Example 60. The scratch test is performed using a nanoindentation device (product name "TI950 TriboIndenter", manufactured by HYSITRON) from the cross section of the overcoat layer to the inside of the overcoat layer (Cube Corner: Ti037_110410 (12)). ) Is pushed in by 50 nm, the depth is kept constant, and the indenter is moved horizontally at a moving speed of 4 μm / min for 30 seconds, and the normal force (load) and horizontal force at that time are measured and measured. The average value of the normal force and the horizontal force was obtained, and the average value of the five average values of the normal force (five times average value) obtained by repeating this scratch test five times was used as the normal force, and the five horizontal forces were used. The average value of the average values (5 times average value) was used as the normal force.

In the light wavelength conversion particles 1 to 8, 11 to 13, 15 to 17 according to Examples 1 to 8, 11 to 13, 15 to 17, the content of a specific element measured by fluorescent X-ray analysis is 0. It was 5.5% by mass or more. On the other hand, in the light wavelength conversion particles 15 according to Comparative Example 1, the content of a specific element measured by fluorescent X-ray analysis was less than 0.5% by mass. In the light wavelength conversion particles 19 according to Comparative Example 1, although the composition 10 for light wavelength conversion particles used for forming the light wavelength conversion particles 19 does not contain a specific element, it is specific. It is considered that the element content of 0.204% by mass is due to the fact that the quantum dots themselves contained 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.

1 ... Light wavelength conversion particles 2 ... Resin particles 3 ... Quantum dots 4 ... Coating layers 10, 20, 30, 40, 50, 60 ... Light wavelength conversion sheets 11 ... Light wavelength conversion layers 16 ... Binder resin 17 ... Light scattering particles 18 ... Coating film 70 ... Image display device 80, 130, 140, 160 ... Backlight device 154, 171 ... Light wavelength converter 120 ... Display panel

Claims (19)

Light wavelength conversion particles
Light-transmitting resin particles containing at least one of one or more elements and carboxylic acids selected from the group consisting of sulfur, phosphorus, and nitrogen.
1 or more and quantum dots included in the resin particles, only including,
The quantum dots include a core made of a first semiconductor compound, a shell made of a second semiconductor compound that covers the core and is different from the first semiconductor compound, and a ligand bound to the surface of the shell. ,
When the resin particles contain sulfur, the resin particles contain at least one of a secondary thiol compound and a tertiary thiol compound.
When the resin particles contain nitrogen, the resin particles contain an amine compound, and the resin particles contain an amine compound.
When the resin particles contain the element, the light wavelength conversion particle in which the content of the element in the light wavelength conversion particle measured by fluorescent X-ray analysis is 0.5% by mass or more . The light wavelength conversion particle according to claim 1, wherein the average particle size of the light wavelength conversion particles is at least twice the average particle size of the quantum dots. The light wavelength conversion particle according to claim 1 or 2 , further comprising a coating layer covering the surface of the resin particles. The light wavelength conversion particle according to claim 3 , wherein the coating layer is a barrier layer that suppresses the permeation of water and oxygen. A light wavelength conversion particle dispersion liquid containing a dispersion medium and the light wavelength conversion particles according to any one of claims 1 to 4 dispersed in the dispersion medium. A light wavelength conversion composition containing the light wavelength conversion particles according to any one of claims 1 to 4 and a polymerizable compound. The light wavelength conversion composition according to claim 6 , further comprising light scattering particles. A light wavelength conversion member comprising the light wavelength conversion particles according to any one of claims 1 to 4. It is an optical wavelength conversion sheet
An optical wavelength conversion sheet comprising a binder resin and an optical wavelength conversion layer including the optical wavelength conversion particles according to any one of claims 1 to 4 dispersed in the binder resin . 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 sheet according to claim 9 , which satisfies at least one of the above. The light wavelength conversion sheet according to claim 9 or 10 , wherein the light wavelength conversion sheet comprises only the light wavelength conversion layer. The light wavelength conversion sheet according to claim 9 or 10 , further comprising an overcoat layer made of a resin, which covers at least one surface of the light wave conversion layer. The light according to claim 9 or 10 , further comprising an optical member on at least one surface side of the light wavelength conversion layer, and the light wavelength conversion layer and the optical member are integrated without an air layer. Wavelength conversion sheet. The light wavelength conversion sheet according to claim 9 , further comprising a barrier film provided on at least one surface of the light wavelength conversion layer and protecting the quantum dots from moisture and oxygen. Light source and
A backlight device comprising the light wavelength conversion member according to claim 8 for receiving light from the light source or the light wavelength conversion sheet according to any one of claims 9 to 14. Optical wavelength conversion member according to claim 8, comprising a backlight apparatus according to the light wavelength conversion sheet or claim 1 5, according to any one of claims 9 to 14, the image display device. The method for producing light wavelength conversion particles according to claim 1.
A light wavelength conversion composition containing at least one of a quantum dot, a compound containing one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, and a carboxylic acid, and a polymerizable compound is cured to obtain the light. The process of obtaining a cured product of the wavelength conversion composition and
It is provided with a step of crushing the cured product .
When the light wavelength conversion composition contains the sulfur-containing compound, the sulfur-containing compound is at least one of a secondary thiol compound and a tertiary thiol compound.
A method for producing light wavelength conversion particles, wherein the light wavelength conversion composition contains a nitrogen-containing compound, and the nitrogen-containing compound is an amine compound. The method for producing light wavelength conversion particles according to claim 1.
An optical wavelength conversion composition containing quantum dots, at least one of a compound containing one or more elements selected from the group consisting of sulfur, phosphorus, and nitrogen, and a carboxylic acid, and a polymerizable compound, was prepared in a poor solvent. The process of dispersing in particles and
A step of polymerizing the polymerizable compound in a state where the light wavelength conversion composition is dispersed in a granular manner is provided .
When the light wavelength conversion composition contains the sulfur-containing compound, the sulfur-containing compound is at least one of a secondary thiol compound and a tertiary thiol compound.
A method for producing light wavelength conversion particles, wherein the light wavelength conversion composition contains a nitrogen-containing compound, and the nitrogen-containing compound is an amine compound. The production method according to claim 18 , wherein the polymerization of the polymerizable compound is suspension polymerization or emulsion polymerization.

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