JP6720603B2 - Light wavelength conversion composition, light wavelength conversion member, light wavelength conversion sheet, backlight device, and image display device - Google Patents

Description

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

A transmissive image display device such as a liquid crystal display device is generally provided with a backlight device which is arranged on the back side of a transmissive image display panel such as a liquid crystal display panel and illuminates the transmissive image display panel.

Currently, in order to improve color reproducibility, incorporation of a light wavelength conversion sheet including a light wavelength conversion member containing a quantum dot and a binder resin into a backlight device is under consideration (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 the backlight device in which the light wavelength conversion sheet is incorporated, various colors can be reproduced while using the 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 sheet may absorb blue light and emit green light and red light. Since a backlight device incorporating such a light wavelength conversion sheet has excellent color purity, an image display device using this backlight device has excellent color reproducibility.

JP, 2015-111518, A

In the light wavelength conversion sheet, the quantum dots may be deteriorated by water and oxygen, which may lower the luminous efficiency.Therefore, a barrier member for suppressing the permeation of water and oxygen should be provided on both surfaces of the light wavelength conversion member. It is provided. Since the barrier member is provided so as to sandwich the light wavelength conversion member, the conventional light wavelength conversion sheet has a structure in which the barrier member, the light wavelength conversion member, and the barrier member are laminated in this order.

On the other hand, in a backlight device, there is a heat resistance test that is left in an environment of 80° C. for 500 hours as one of the reliability tests that are usually performed, and each member of the backlight device uses the standard of this heat resistance test. It is desired to meet. However, when a heat resistance test is performed on the light wavelength conversion sheet having the above structure, there is a problem that the quantum dots deteriorate and the brightness decreases.

In addition, in the light wavelength conversion sheet including the barrier member, when a heat resistance test is performed, pinholes and cracks are easily generated in the barrier member. If pinholes or cracks occur in the barrier member, moisture or oxygen may enter from there and some quantum dots may deteriorate, resulting in a spot-like portion (luminance defect) in the light wavelength conversion sheet where the luminance decreases in a dot shape. There is. The dot-like luminance defect is more easily visually recognized than when the quantum dots are deteriorated as a whole and the luminance is uniformly lowered. Further, at present, it is desired to further reduce the thickness of the light wavelength conversion sheet and reduce the manufacturing cost. For these reasons, it is currently considered not to use a barrier member. However, the current light wavelength conversion member does not have a function of protecting the quantum dots from moisture and oxygen, so that the quantum dots deteriorate unless the barrier member is used.

The present invention has been made to solve the above problems. That is, an object is to provide a light wavelength conversion composition and a light wavelength conversion member having excellent heat resistance. Further, a light wavelength conversion sheet which has excellent heat resistance and can omit the barrier member, or can suppress the dot-like luminance defect even when the barrier member is used, such a light wavelength conversion member or light wavelength It is an object to provide a backlight device and an image display device provided with a conversion sheet.

The inventors of the present invention have made extensive studies on the above problems, and as a result, by including a phosphite compound in the light wavelength conversion composition, the light wavelength conversion composition and the light wavelength conversion member having excellent heat resistance. In addition, when a light wavelength conversion sheet is formed using this light wavelength conversion member, it has excellent heat resistance and can omit the barrier member, or even when using a barrier member It was found that the luminance defect of 1 can be suppressed. The present invention has been completed based on such findings.

式中、Ｘ^１〜Ｘ^３は、それぞれ独立して、酸素原子または硫黄原子を表し、Ｒ^１〜Ｒ^３は、それぞれ独立して、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表し、またＲ^２およびＲ^３は互いに結合して環状構造を形成してもよい。

式中、Ｒ^４は、それぞれ独立して、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表し、Ｒ^５は、水素原子、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表す。 According to one aspect of the present invention, there is provided a light wavelength conversion composition comprising a quantum dot, a compound represented by the following general formula (1) and a compound represented by the following general formula (2). Provided is a light wavelength conversion composition including at least one phosphite-based compound selected.

In the formula, X ^{1 to} X ³ each independently represent an oxygen atom or a sulfur atom, and R ^{1 to} R ³ each independently represent an optionally substituted alkyl group or an optionally substituted alkyl group. Cycloalkyl group, optionally substituted alkenyl group, optionally substituted cycloalkenyl group, optionally substituted alkynyl group, optionally substituted aryl group, or optionally substituted aralkyl group And R ² and R ³ may combine with each other to form a cyclic structure.

In the formula, R ^{4 s} are each independently an optionally substituted alkyl group, an optionally substituted cycloalkyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkenyl group, Represents an optionally substituted alkynyl group, an optionally substituted aryl group, or an optionally substituted aralkyl group, R ⁵ is a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted Optionally substituted cycloalkyl group, optionally substituted alkenyl group, optionally substituted cycloalkenyl group, optionally substituted alkynyl group, optionally substituted aryl group, or optionally substituted Represents an aralkyl group.

According to another aspect of the present invention, there is provided a light wavelength conversion member comprising a cured product of the above light wavelength conversion composition.

According to another aspect of the present invention, there is provided a light wavelength conversion sheet, which is provided with the above-mentioned light wavelength conversion member, and in which the light wavelength conversion member is formed in layers.

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

According to the light wavelength conversion composition of one aspect of the present invention and the light wavelength conversion member of another aspect, since the phosphite-based compound is contained, the light wavelength conversion composition and the light wavelength conversion having excellent heat resistance. A member can be provided. Further, according to another aspect of the present invention, since the light wavelength conversion sheet is formed by using this light wavelength conversion member, it has excellent heat resistance, and the barrier member can be omitted, or the barrier member is used. Even in the case, it is possible to provide a light wavelength conversion sheet capable of suppressing the dot-like luminance defect. Further, according to another aspect of the present invention, it is possible to provide a backlight device and an image display device including such a light wavelength conversion member or a light wavelength conversion sheet.

It is a schematic block diagram of the light wavelength conversion sheet which concerns on embodiment. It is a figure which shows the effect|action of the light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is sectional drawing which followed the II line|wire of the light wavelength conversion sheet of FIG. It is a schematic block diagram of the other light wavelength conversion sheet which concerns on embodiment. It is a schematic block diagram of the other 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. FIG. 1 is a schematic configuration diagram of an image display device including a backlight device according to an embodiment. FIG. 12 is a perspective view of the lens sheet shown in FIG. 11. It is sectional drawing which followed the II-II line of the lens sheet of FIG. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment. It is a schematic block diagram of the light source shown by FIG. It is a schematic block diagram of the other backlight apparatus which concerns on embodiment. FIG. 18 is an enlarged view of the vicinity of a light entrance surface of the optical plate shown in FIG. 17.

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

<<<light wavelength conversion composition>>>
The light wavelength conversion composition is a composition for converting the wavelength of a part of the incident light into another wavelength and emitting the other part of the incident light and the wavelength-converted light. The light wavelength conversion composition contains quantum dots and a phosphite compound described later. The light wavelength conversion composition may be used in the form of a composition, or may be used in the state of a light wavelength conversion member which is a cured product after curing the light wavelength conversion composition. In the present specification, the “light wavelength conversion member” is a member substantially made of a cured product of the light wavelength conversion composition. Here, the term “substantially” means that the light wavelength conversion member may contain some substance other than the cured product of the light wavelength conversion composition. The light wavelength conversion member may be a member composed only of a cured product of the light wavelength conversion composition. When forming the light wavelength conversion member, the light wavelength conversion composition further contains a polymerizable compound, and may further contain a polymerization initiator in addition to the polymerizable compound. The light wavelength conversion composition preferably further contains light scattering particles, and may further contain an additive or a solvent.

The viscosity of the light 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 10,000 mPa·s, the light wavelength conversion composition may be coated. The coating may be difficult and the leveling property may be deteriorated. 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 10,000 mPa·s or less.

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

Specifically, the quantum dot has a larger energy band gap as the particle diameter becomes smaller. That is, as the crystal size becomes smaller, the quantum dot emission shifts to the blue side, that is, to the higher energy side. Therefore, by changing the particle size of the quantum dots, the emission wavelength can be adjusted over the entire wavelength range of the spectrum in the ultraviolet region, the visible region, and the infrared region. For example, when the quantum dots are composed of CdSe/ZnS described below, blue light is emitted when the particle size of the quantum dots is 2.0 nm or more and 4.0 nm or less, and the particle size of the quantum dots is 3.0 nm. When it is 6.0 nm or less, green light is emitted, and when the particle size of the quantum dot is 4.5 nm or more and 10.0 nm or less, red light is emitted. In the above, the particle size range of the quantum dots emitting blue light and the particle size range of the quantum dots emitting green light partially overlap, and the particle size of the quantum dots emitting green light and the red light are Although the range of the particle size of the emitted quantum dots partially overlaps, even if the quantum dots have the same particle size, the emission color may differ depending on the size of the quantum dot core. Not something to do.

As the quantum dot, one kind of quantum dot may be used, but it is also possible to use two or more kinds of quantum dots each having an emission band of a single wavelength region due to the difference in particle diameter, material and the like. .. Specifically, the light wavelength conversion composition may include a first quantum dot and a second quantum dot having an emission band in a wavelength range different from that of the first quantum dot.

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

The quantum dot is composed of, for example, a core made of a first semiconductor compound, a shell made of a second semiconductor compound different from the first semiconductor compound and covering the core, and a ligand bound to the surface of the shell. Has been done.

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

As the second semiconductor compound forming the shell, it is preferable to use a semiconductor compound having a bandgap higher than that of the first semiconductor compound forming 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 forming the shell include ZnS, ZnSe, CdS, GaN, CdSSe, ZnSeTe, AlP, ZnSTe, ZnSSe and the like.

Specific combinations of core-shell structures (core/shell) composed of a core and a shell include, for example, CdSe/ZnS, CdSe/ZnSe, CdSe/CdS, CdTe/CdS, InP/ZnS, Gap/ZnS, Si/ZnS, InN/GaN, InP/CdSSe, InP/ZnSeTe, InGaP/ZnSe, InGaP/ZnS, Si/AlP, InP/ZnSTe, InP/ZnSSe, InGaP/ZnSTe, InGaP/ZnSSe, etc. may be mentioned.

The ligand is for stabilizing the unstable quantum dots. Examples of the ligand include sulfur compounds such as thiols, phosphine compounds, phosphorus compounds such as phosphine oxides, nitrogen compounds such as amines, and carboxylic acids.

The shape of the quantum dot is not particularly limited, and may be, for example, a spherical shape, a rod shape, a disk shape, or another shape. When the shape of the semiconductor nanoparticles is not spherical, the particle diameter of the semiconductor nanoparticles can be a true spherical value having the same volume.

Information such as the particle size, average particle size, shape, and dispersion state of the quantum dots can be obtained with a transmission electron microscope or a scanning transmission electron microscope. The average particle diameter of the quantum dots can be obtained as an average value of the diameters of 20 quantum dots measured by observation with a transmission electron microscope or a scanning transmission electron microscope. Moreover, since the emission color of the quantum dots changes depending on the particle diameter, it is also possible to determine the particle diameter of the quantum dots by confirming the emission color of the quantum dots. The crystal structure and crystallite size of the quantum dots can be known by X-ray crystal diffraction (XRD). Furthermore, it is possible to obtain information on the particle size of the quantum dots and the like from the ultraviolet-visible (UV-Vis) absorption spectrum.

The content of the quantum dots with respect to the total solid content of the light wavelength conversion composition is preferably 0.01% by mass or more and 2% by mass or less, and more preferably 0.03% by mass or more and 1% by mass or less. .. When the content of the quantum dots is less than 0.01% by mass, sufficient emission intensity may not be obtained, and when the content of the quantum dots exceeds 2% by mass, sufficient transmitted light of excitation light is obtained. The strength may not be obtained.

式中、Ｘ^１〜Ｘ^３は、それぞれ独立して、酸素原子または硫黄原子を表し、Ｒ^１〜Ｒ^３は、それぞれ独立して、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表し、またＲ^２およびＲ^３は互いに結合して環状構造を形成してもよい。

式中、Ｒ^４は、それぞれ独立して、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表し、Ｒ^５は、水素原子、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表す。 <<phosphite compounds>>
The phosphite compound used in the present invention is at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). The "phosphite compound" in the present specification is a concept including not only phosphite but also phosphonate. Generally, phosphite and phosphonate are in a tautomeric relationship.

In the formula, X ^{1 to} X ³ each independently represent an oxygen atom or a sulfur atom, and R ^{1 to} R ³ each independently represent an optionally substituted alkyl group or an optionally substituted alkyl group. Cycloalkyl group, optionally substituted alkenyl group, optionally substituted cycloalkenyl group, optionally substituted alkynyl group, optionally substituted aryl group, or optionally substituted aralkyl group And R ² and R ³ may combine with each other to form a cyclic structure.

In the formula, R ^{4 s} are each independently an optionally substituted alkyl group, an optionally substituted cycloalkyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkenyl group, Represents an optionally substituted alkynyl group, an optionally substituted aryl group, or an optionally substituted aralkyl group, R ⁵ is a hydrogen atom, an optionally substituted alkyl group, or an optionally substituted Optionally substituted cycloalkyl group, optionally substituted alkenyl group, optionally substituted cycloalkenyl group, optionally substituted alkynyl group, optionally substituted aryl group, or optionally substituted Represents an aralkyl group.

X ^{1 to} X ³ are oxygen atoms or sulfur atoms, but if the size of the atom adjacent to phosphorus is large, steric hindrance may occur and the phosphite compound may not be able to bond to the quantum dots. An oxygen atom having a small atomic size is preferable.

The alkyl group, alkenyl group, or alkynyl group for R ^{1 to} R ⁵ may be linear or branched, but is linear in view of small steric hindrance when binding to quantum dots. Is preferred.

The number of carbon atoms of the alkyl group, alkenyl group, or alkynyl group for R ^{1 to} R ⁵ is preferably 1 or more and 20 or less. If the carbon number of the alkyl group, alkenyl group, or alkynyl group exceeds 20, the quantum dots may deteriorate during the heat resistance test. The lower limit of the carbon number of the alkyl group, alkenyl group, or alkynyl group in R ^{1 to} R ⁵ is more preferably 6 or more, and the upper limit is more preferably 12 or less.

Examples of the alkyl group for R ^{1 to} R ⁵ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl, n-hexyl, Examples thereof include n-octyl group, 2-ethylhexyl group, decyl group, lauryl group, tridecyl group and stearyl group. An oleyl group is mentioned as said alkenyl group.

The number of carbon atoms of the cycloalkyl group or cycloalkenyl group in R ^{1 to} R ⁵ is preferably 3 or more and 10 or less. When the cycloalkyl group or the cycloalkenyl group has more than 10 carbon atoms, the quantum dots may deteriorate during the heat resistance test. The lower limit of the carbon number of the cycloalkyl group or the cycloalkenyl group in R ^{1 to} R ⁵ is more preferably 5 or more, and the upper limit is more preferably 8 or less.

Examples of the cycloalkyl group for R ^{1 to} R ⁵ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of the cycloalkenyl group include a cyclopropenyl group, a cyclopentenyl group, and a cyclohexenyl group.

The aryl group for R ^{1 to} R ⁵ may be a monocycle or a condensed ring. The aryl group preferably has 6 or more and 10 or less carbon atoms. When the carbon number of the aryl group exceeds 12, the phosphite compound may not be able to bond to the quantum dots due to the problem of steric hindrance. Examples of the aryl group include a phenyl group, a cresyl group, a xylyl group, an isopropylphenyl group, a butylphenyl group, a tert-butylphenyl group, a di-tert-butylphenyl group, a p-cumylphenyl group and a naphthyl group. , And a phenyl group is more preferable.

The number of carbon atoms of the aralkyl group in R ^{1 to} R ⁵ is preferably 7 or more and 10 or less. When the carbon number of the aralkyl group exceeds 10, the phosphite compound may not be able to bond with the quantum dot due to steric hindrance. Examples of the aralkyl group include a benzyl group, a phenethyl group, a tolylmethyl group, a phenylbutyl group and the like.

When the alkyl group, alkenyl group, or alkynyl group in R ^{1 to} R ⁵ has a substituent, the substituent is a halogen atom, a hydroxyl group, a cycloalkyl group (for example, having 3 to 10 carbon atoms), Examples include a group selected from a cycloalkenyl group (for example, having 3 to 10 carbon atoms), an alkoxyl group (for example, having 1 to 20 carbon atoms), an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom.

When the cycloalkyl group or cycloalkenyl group in R ^{1 to} R ⁵ has a substituent, the substituent may be a halogen atom, a hydroxyl group, an alkyl group (for example, having 1 to 20 carbon atoms), an alkenyl group ( For example, C1 or more and 20 or less), alkynyl group (for example, C1 or more and 20 or less), alkoxyl group (for example, C1 or more and 20 or less), aryl group (for example, C6 or more and 10 or less), aryl Examples include groups selected from an oxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group and the like.

When the aryl group in R ^{1 to} R ⁵ has a substituent, the substituent is a halogen atom, a hydroxyl group, an alkyl group (for example, having 1 to 20 carbon atoms), an alkenyl group (for example, having 1 carbon atom). 20 or more), an alkynyl group (for example, 1 or more and 20 or less carbon atoms), an alkoxyl group (for example, 1 or more and 20 or less carbon atoms), an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group, or the like. Groups.

When the aralkyl group in R ^{1 to} R ⁵ has a substituent, the substituent is a halogen atom, a hydroxyl group, an alkyl group (for example, having 1 to 20 carbon atoms), an alkenyl group (for example, having 1 carbon atom). 20 or more), an alkynyl group (for example, 1 or more and 20 or less carbon atoms), an alkoxyl group (for example, 1 or more and 20 or less carbon atoms), an aryloxy group, an acyl group, an alkoxycarbonyl group, a carboxyl group, or the like. Groups.

The alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, aryl group, or two or more methylene groups not adjacent to each other in the aralkyl group in R ^{1 to} R ⁵ are —O—, _{-S -, - SO 2 -,} - CO -, - COO -, - OCO -, - NR '-, - CONR' -, - NR'CO-, and selected from the group consisting of -N = CH- It may be substituted with at least one group. The R's each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

Among the compounds represented by the general formula (1), a compound in which at least one of R ^{1 to} R ³ is an alkyl group, an alkenyl group, or an aryl group is preferable from the viewpoint of further improving heat resistance. Among these, a compound in which at least one of R ^{1 to} R ³ is an aryl group is more preferable.

式中、Ｒ^６は、置換されていてもよいアルキル基または置換されていてもよいアルケニル基を表し、Ｒ^６が複数存在する場合は同じでもあっても、異なっていてもよく、ｎは、０〜５の整数を表し、＊は、結合位置を表す。 Among least one of the R ¹ to R ³ is a phosphite is an aryl group, more at least one of the R ¹ to R ³ are compounds where an aryl group represented by the following general formula (3) preferable. When at least one of R ^{1 to} R ³ is an aryl group represented by the following general formula (3), all of R ^{1 to} R ³ are aryl groups represented by the following general formula (3). May be.

In the formula, R ⁶ represents an optionally substituted alkyl group or an optionally substituted alkenyl group, and when a plurality of R ⁶ are present, they may be the same or different, and n is It represents an integer of 0 to 5, and * represents a bonding position.

The alkyl group or alkenyl group for R ⁶ may be linear or branched, but is preferably linear from the viewpoint of less steric hindrance when binding to the quantum dots.

The carbon number of the alkyl group or alkenyl group in R ⁶ is preferably 1 or more and 20 or less. When the number of carbon atoms of the alkyl group or alkenyl group in R ⁶ exceeds 20, the quantum dots may deteriorate during the heat resistance test. The lower limit of the carbon number of the alkyl group or alkenyl group in R ⁶ is more preferably 6 or more, and the upper limit is more preferably 12 or less.

Examples of the alkyl group or alkenyl group for R ⁶ include those similar to the alkyl group or alkenyl group for R ^{1 to} R ^5, and thus description thereof will be omitted here.

式中、Ｒ^１は上記と同じ意味であり、Ｒ^７は、置換されていてもよいアルキル基、置換されていてもよいシクロアルキル基、置換されていてもよいアルケニル基、置換されていてもよいシクロアルケニル基、置換されていてもよいアルキニル基、置換されていてもよいアリール基、または置換されていてもよいアラルキル基を表す。 When R ² and R ³ are bonded to each other to form a cyclic structure, the compound represented by the general formula (1) may be a compound containing two phosphorus atoms in one molecule. Good. When R ² and R ³ are bonded to each other to form a cyclic structure, examples of the compound represented by the general formula (1) include compounds represented by the following general formula (4).

In the formula, R ¹ has the same meaning as described above, and R ⁷ represents an optionally substituted alkyl group, an optionally substituted cycloalkyl group, an optionally substituted alkenyl group, or an optionally substituted. It represents a good cycloalkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl group, or an optionally substituted aralkyl group.

Alkyl group of the R ^7, cycloalkyl group, alkenyl group, cycloalkenyl group, an alkynyl group, an aryl group, the carbon number of the aralkyl group, the structure and substituents such as alkyl groups represented by R ¹ to R ^5, cycloalkyl group, It is the same as an alkenyl group, a cycloalkenyl group, an alkynyl group, an aryl group, and an aralkyl group, and therefore description thereof will be omitted here.

If the weight average molecular weight of the compound represented by the general formula (1) or the weight average molecular weight of the compound represented by the general formula (2) is too small, it may volatilize after processing and is too large. Therefore, the compatibility with the polymerizable compound may decrease, so that it is preferably 200 or more and 1000 or less. 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 compound represented by the general formula (1) or the weight average molecular weight of the compound represented by the general formula (2) is preferably 300 or more, and more preferably 700 or less. ..

Specific examples of the compound represented by the general formula (1) include triethylphosphite, tris(2-ethylhexyl)phosphite, triisooctylphosphite, tridecylphosphite, triisodecylphosphite, trilaurylphosphite. Fight, tris(tridecyl)phosphite, tristearyl phosphite, trioleyl phosphite, trilauryl trithiophosphite, triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, tris(2,4-di- tert-butylphenyl)phosphite, diphenylmono(2-ethylhexyl)phosphite, diphenylmonodecylphosphite, diphenylmono(tridecyl)phosphite, phenyldiisodecylphosphite, tetraphenyldipropyleneglycol diphosphite, tetra( C12-C15 alkyl)-4,4'-isopropylidene diphenyl diphosphite, bis(decyl) pentaerythritol diphosphite, bis(tridecyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, hydrogenated bisphenol A Examples include pentaerythritol phosphite polymer and hydrogenated bisphenol A phosphite polymer. Among these, triphenyl phosphite, trisnonyl phenyl phosphite, and phenyl diisodecyl phosphite having an aryl group in the molecule are preferable.

Examples of commercially available compounds represented by the general formula (1) include JP-3360, JP-351, JP-3CP, JP302, JP308E, JP-310, JP-312L, JP-333E and JP-318. -O, JPM-308, JPM-311, JPM-313, JPS-312, JPP-100, JPP-613M, JA-805, JPP-88, JPE-10, JPE-13R, JPE-13R, JP-318E. , JPP-2000PT, JP-650, JPH-3800, HBP (all manufactured by Johoku Chemical Industry Co., Ltd.), Chelex O, Chelex D, Chelex TDP, Chelex 2300, Chelex OL (all manufactured by SC Organic Chemical Co., Ltd.). ..

Specific examples of the compound represented by the general formula (2) include diethyl hydrogen phosphite, di-2-ethylhexyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, and diphenyl hydrogen phosphite. To be Among these, di-2-ethylhexyl hydrogen phosphite, diphenyl hydrogen phosphite, and the like are preferable from the viewpoint of excellent compatibility with the polymerizable compound and being less likely to volatilize after processing.

Examples of commercially available compounds represented by the general formula (2) include JP-202, JPE-208, JP-212, JP-213D, JP-218-OR, and JP-260 (all of them are Johoku Chemical Industry Co., Ltd. Company), Chelex H-8, Chelex H-12, Chelex H-18D, Chelex H-18TA (all manufactured by SC Organic Chemical Co., Ltd.).

The phosphite compound may include a group capable of crosslinking with a polymerizable compound such as an ethylenically unsaturated group (crosslinkable group).

Whether or not the phosphite compound is contained in the light wavelength conversion composition is (1) infrared spectroscopic analysis (IR), (2) gas chromatography analysis (GCMS), (3) gel permeation chromatography. It can be confirmed by the combined use of analysis (GPC) and nuclear magnetic resonance spectroscopy (NMR spectroscopy). Specifically, the compounds contained in the light wavelength conversion composition can be roughly specified in the infrared spectroscopic analysis, and the molecular weight of the compound contained in the light wavelength conversion composition can be specified in the gas chromatography analysis. Compounds contained in the light wavelength conversion composition can be separated in the permeation chromatography analysis, and structural formulas of the compounds contained in the light wavelength conversion composition can be specified in the nuclear magnetic resonance spectroscopy analysis. By using it, it is possible to confirm whether the phosphite compound is contained in the light wavelength conversion composition.

The content of the phosphite compound in the light wavelength conversion composition is preferably 1% by mass or more. If the content of the phosphite compound is less than 1% by mass, deterioration of the quantum dots may not be suppressed during the heat resistance test. The content of the phosphite compound can be confirmed by the same method as the method for confirming whether or not the phosphite compound is present in the light wavelength conversion composition. Specifically, for example, the phosphite-based compound contained in the light wavelength conversion composition is identified (identified) by nuclear magnetic resonance spectroscopy, and then gas chromatography analysis or gel permeation chromatography corresponding to the phosphite-based compound is performed. The content of the phosphite compound in the light wavelength conversion composition can be determined from the peak area ratio obtained by the graphic analysis. When a plurality of types of phosphite compounds are used, the above content means the total content of the plurality of types of phosphite compounds. The lower limit of the content of the phosphite compound in the light wavelength conversion composition is more preferably 5% by mass or more, and the upper limit of the content of the phosphite compound is preferably 30% by mass or less. More preferably 20% by mass or less. When the content of the phosphite-based compound exceeds 30% by mass, the adhesion with the light transmissive substrate may be deteriorated, and aggregation or the like may occur after processing.

<<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 thermopolymerizable compound (thermosetting compound). Examples of the ionizing radiation in the present specification include visible light, ultraviolet rays, X-rays, electron beams, α rays, β rays, and γ rays.

The content of the polymerizable compound with respect to the total solid content of the light wavelength conversion composition is preferably 30% by mass or more and 95% by mass or less, and more preferably 50% by mass or more and 90% by mass or less. When the content of the polymerizable compound is less than 30% by mass, sufficient curability may not be obtained during the formation of the light wavelength conversion member, and the content of the polymerizable compound exceeds 95% by mass. If so, the effect of improving heat resistance by the phosphite compound may not be sufficiently obtained. When the light wavelength conversion composition contains both an ionizing radiation-polymerizable compound and a heat-polymerizable compound described below, the content means the total content of the ionizing radiation-polymerizable compound and the heat-polymerizable compound. I shall.

<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” is meant to include both “acryloyl group” and “methacryloyl group”.

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. The ionizing radiation-polymerizable compound is preferably a combination of an ionizing radiation-polymerizable monomer and an ionizing radiation-polymerizable oligomer or an ionizing radiation-polymerizable prepolymer.

Examples of the ionizing radiation-polymerizable monomer include monomers having 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, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(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 (Meth)acrylic acid esters such as

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 ionizing radiation-polymerizable functional groups (trifunctional) 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, 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, more preferably 10,000 or more and 40,000 or less. When the weight average molecular weight is more than 80,000, the viscosity is so high that the coating suitability is deteriorated, and the appearance of the obtained light wavelength conversion member may be deteriorated. Therefore, when the 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 polymerizable monomer or the 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 cyclic ether groups such as epoxy groups and oxetanyl groups, vinyl ether groups, and the like.

Examples of the heat-polymerizable compound include cyclic ether compounds having one or more cyclic ether groups in the molecule, such as epoxy compounds and oxetane compounds, and vinyl ether compounds. As the cationically polymerizable compound, a cyclic ether compound is preferable from the viewpoint of further suppressing the occurrence of tunneling, and among the cyclic ether compounds, an epoxy compound is preferable.

The epoxy compound is a compound having one or more epoxy groups in the molecule. The epoxy compound is not particularly limited, and examples thereof include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, biphenyl type epoxy compound, fluorene type epoxy compound, novolac phenol type epoxy compound, cresol novolac type epoxy compound. Compounds, aromatic compounds such as 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 alkylene oxide adducts thereof A polyglycidyl ether of a polyhydric alcohol such as di- or triglycidyl ether, a diglycidyl ether of polyethylene glycol or an alkylene oxide adduct thereof, a polyalkylene glycol diglycidyl ether such as a polypropylene glycol or a diglycidyl ether of an alkylene oxide adduct thereof, And aliphatic type such as alkylene oxide. Here, examples of the alkylene oxide include aliphatic epoxy compounds such as ethylene oxide and propylene oxide, 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and 3,4-epoxycyclohexylmethyl methacrylate. Examples thereof include alicyclic epoxy compounds having one or more epoxy groups and one or more ester groups in the molecule. Of these, alicyclic epoxy compounds such as 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and 3,4-epoxycyclohexylmethyl methacrylate are preferable in terms of adhesive strength and curability. ..

<< polymerization initiator >>
The polymerization initiator is a component that is decomposed by light or heat to generate radicals or ionic species to start or proceed with polymerization (crosslinking) of the polymerizable compound. Examples of the polymerization initiator include photopolymerization initiators (eg, photoradical polymerization initiators, photocationic polymerization initiators, photoanionic polymerization initiators), thermal polymerization initiators (eg, thermal radical polymerization initiators, thermal cationic polymerization initiators). , Thermal anionic polymerization initiator), or a mixture thereof.

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

Examples of commercially available photoradical polymerization initiators include, for example, IRGACURE 184, IRGACURE 369, IRGACURE 379, IRGACURE 651, IRGACURE 819, IRGACURE 907, IRGACURE 2959, IRGACURE OXE 01, Lucilin TPO (all of which are manufactured by BASF Japan 9). ADEKA), SPEEDCURE EMK (Nippon Sebel Hegner), benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.) and the like.

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

Examples of the thermal radical polymerization initiator include peroxides and azo compounds. Among these, polymer azo initiators composed of polymer azo compounds are preferable. Examples of the high molecular weight 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, for example, a polycondensation product of 4,4′-azobis(4-cyanopentanoic acid) and polyalkylene glycol. And polycondensation products of 4,4′-azobis(4-cyanopentanoic acid) and polydimethylsiloxane having a terminal amino group.

Examples of the above-mentioned peroxide include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxy ester, diacyl peroxide, and peroxydicarbonate.

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, 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 quaternary ammonium salt, phosphonium salt and sulfonium salt. Examples of commercially available thermal cationic 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, Sun-Aid SI-100L ( Examples include Sanshin Chemical Industry Co., Ltd., CI series (Nippon Soda Co., Ltd.) and the like.

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. When the content of the polymerization initiator is less than 0.3 parts by mass, the polymerizable compound is hard to cure, and when it exceeds 5.0 parts by mass, the light wavelength conversion sheet may be yellowed. ..

<<Light-scattering particles>>
The light-scattering particles are particles having a function of changing the traveling direction of light by scattering light that has entered the light wavelength conversion member.

The average particle diameter 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 diameter of the quantum dots. When the average particle diameter of the light scattering particles is less than 20 times the average particle diameter of the quantum dots, sufficient light scattering performance may not be obtained in the light wavelength conversion member, and the average particle diameter of the light scattering particles may be If the average particle size of the quantum dots exceeds 2000 times, the number of light-scattering particles will decrease even if the addition amount is the same, so the number of scattering points will decrease and there is a possibility that a sufficient light-scattering effect cannot be obtained. .. The average particle size of the light-scattering particles can be measured by the same method as the average particle size of the quantum dots described above.

The average particle diameter of the light-scattering particles is preferably 1/300 or more and 1/20 or less, more preferably 1/200 or more and 1/30 or less of the average film thickness of the light wavelength conversion member described later. preferable. If the average particle diameter of the light-scattering particles is less than 1/300 of the average film thickness of the light-wavelength converting member, sufficient light-scattering performance may not be obtained in the light-wavelength converting member. If the particle diameter exceeds 1/20 of the average film thickness of the light wavelength conversion member, the ratio of light scattering particles to the light wavelength conversion member will decrease even if the addition amount is the same, so the number of scattering points will decrease sufficiently. No light scattering effect.

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 in order to obtain sufficient light scattering properties, It is necessary to increase the addition amount. On the other hand, if 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, and the number of scattering points decreases, resulting in a sufficient light-scattering effect. I can't get it.

The shape of the light-scattering particles is not particularly limited, and includes, for example, spherical shape (true spherical shape, substantially true spherical shape, elliptic spherical shape, etc.), polyhedral shape, rod shape (cylindrical shape, prismatic shape, etc.), flat plate shape, scale shape, and irregular shape. Etc. The particle size of the light-scattering particles can be a value of a true sphere having the same volume when the shape of the light-scattering particles is not spherical.

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

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

The light-scattering particles may be organic particles such as acrylic resin particles, styrene resin particles, melamine resin particles, and urethane resin particles, but it is possible to reduce the rate of change in luminance before and after the heat resistance test. Inorganic particles are preferable because the incident light to the wavelength conversion sheet can be scattered appropriately and the light wavelength conversion efficiency with respect to the incident light can be suitably 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), magnesium-containing compounds 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. Since these inorganic particles can increase the difference in refractive index from the binder resin, they are also preferable from the viewpoint that a large Mie scattering intensity can be obtained. The light-scattering particles may be made of two or more kinds of materials because the light-wavelength conversion sheet 10 can more appropriately improve the light-wavelength conversion efficiency with respect to the incident light.

The content of the light-scattering particles with respect to the total solid content 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. When the content of the light scattering particles is less than 1% by mass, the light scattering effect may not be sufficiently obtained, and when the content of the light scattering particles exceeds 50% by mass, Mie scattering occurs. Since it becomes difficult, the light-scattering effect may not be sufficiently obtained, and further, the workability may be deteriorated due to too many light-scattering particles.

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

<<solvent>>
The solvent is not particularly limited, but 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 and light wavelength conversion sheet>>>
The light wavelength conversion sheet 10 shown in FIG. 1 is a sheet that converts the wavelength of a part of the incident light into another wavelength and emits another part of the incident light and the wavelength-converted light. is there. The light wavelength conversion sheet 10 shown in FIG. 1 includes a layered light wavelength conversion member 11, light transmissive substrates 12 and 13 provided on both surfaces of the light wavelength conversion member 11, and light transmissive substrates 12 and 13. The light diffusing layers 14 and 15 provided on the side opposite to the surface on the side of the light wavelength conversion member 11 in. In the light wavelength conversion sheet 10, the surfaces of the light diffusion layers 14 and 15 form the surfaces 10A and 10B of the light wavelength conversion sheet 10. The light wavelength conversion sheet 10 includes the light transmissive base materials 12 and 13, but does not include a barrier layer, and thus does not include a barrier member including the light transmissive base material and the barrier layer. The light wavelength conversion sheet 10 has a structure of light diffusion layer 14/light transmissive base material 12/light wavelength conversion member 11/light transmissive base material 13/light diffusion layer 15. The structure of the light wavelength conversion sheet is not particularly limited as long as it has

In the light wavelength conversion sheet 10, as shown in FIG. 2, when light is incident from the surface 10A of the light wavelength conversion sheet 10, the light L1 incident on the quantum dots 17 in the light wavelength conversion member 11 is The light L1 is converted into light L2 having a different wavelength and emitted from the surface 10B. On the other hand, even when the light is incident from the surface 10A, the light L1 passing between the quantum dots 17 in the light wavelength conversion member 11 is emitted from the surface 10B without wavelength conversion.

In the light wavelength conversion sheet 10, the water vapor transmission rate (WVTR) at 40° C. and 90% relative humidity may be 0.1 g/(m ² ·24 h) or more in the entire sheet. .. The water vapor transmission rate 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). Since the conventional light wavelength conversion sheet has the barrier member formed therein, the light wavelength conversion sheet 10 has a higher water vapor transmission rate than the conventional light wavelength conversion sheet, that is, the light wavelength conversion sheet 10 is Compared to the conventional light wavelength conversion sheet, it is easier for water to pass through. As will be described later, when the light wavelength conversion sheet is provided with an optical member in addition to the light wavelength conversion member, the water vapor transmission rate is the water vapor transmission rate of the entire light wavelength conversion sheet including the optical member.

In the light wavelength conversion sheet 10, the oxygen transmission rate (OTR: Oxygen Transmission Rate) at 23° C. and 90% relative humidity is 0.1 cm ³ /(m ² ·24 h·atm) or more in the entire sheet. Good. 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). Since the conventional light wavelength conversion sheet has the barrier member 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 is Compared to the conventional light wavelength conversion sheet, oxygen as well as water easily penetrates. Similarly to the above, when the light wavelength conversion sheet includes an optical member in addition to the light wavelength conversion member, the oxygen transmittance is the oxygen transmittance of the entire light wavelength conversion sheet including the optical member.

The water vapor conversion rate of the light wavelength conversion sheet 10 at 40° C. and 90% relative humidity may be 1 g/(m ² ·24 h) or more, and at 23° C. and 90% relative humidity of the light wavelength conversion sheet 10. May have an oxygen permeability of 1 cm ³ /(m ² ·24h·atm) or more.

The internal haze value in the light wavelength conversion sheet 10 is preferably 50% or more. The internal haze is a haze value due to 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 light wavelength conversion sheet 10 is 50% or more, light can be sufficiently diffused by the internal haze to excite the quantum dots a plurality of times, and the external haze value can be made smaller. You can The internal haze value in the light wavelength conversion sheet 10 is preferably 60% or more, and more preferably 80% or more.

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

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

The internal haze value and the external haze value can be determined using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory). Specifically, first, using a haze meter, the total haze value of the light wavelength conversion sheet is measured according to JIS K7136:2000. Then, on both sides of the light wavelength conversion sheet, a triacetyl cellulose base material (product name: “Panaclean PD-S1” manufactured by Panac) with a film thickness of 25 μm is interposed between the triacetyl cellulose base material (product name: TD60UL" manufactured by FUJIFILM Corporation) is attached. 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, an 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 Research Laboratory). Also, the external haze value is obtained by subtracting the internal haze from the total haze. The "external haze value" in this specification means the external haze value of the entire light wavelength conversion sheet. That is, the external haze value in this 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.

There is a relationship between the internal haze value and the external haze value. Specifically, when the internal haze value increases, the external haze tends to decrease even when the same surface unevenness is provided. This is considered to be due to the following reasons. JIS K7136:2000 stipulates that the haze is the percentage of the transmitted light passing through the test piece, which is deviated from the incident light by 0.044 rad (2.5°) or more 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, as compared with the light wavelength conversion sheet having a smaller internal haze, the light is more scattered inside the sheet, so that for the incident light reaching the sheet surface. There is less transmitted light below 2.5°. Therefore, when the internal wavelength haze has a large light wavelength conversion sheet and the internal wavelength haze is smaller than that of the light wavelength conversion sheet has the same surface irregularities, the internal wavelength haze is larger than the optical wavelength conversion sheet, the internal haze is larger 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 irregularities present on the sheet surface, even if the internal wavelength haze is smaller than the optical wavelength conversion sheet having a large internal haze, the internal wavelength may be the same. Compared with a light wavelength conversion sheet having a smaller internal haze, a light wavelength conversion sheet having a large haze not only transmits light of less than 2.5° with respect to incident light emitted from the surface unevenness but also has a surface roughness. The amount of transmitted light deviated by 2.5° or more from the incident light emitted from is also reduced. Therefore, it is considered that when the internal haze value becomes large, the external haze becomes small even when 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, addition of light scattering particles inside the light wavelength conversion sheet 10 can be mentioned. .. When the light wavelength conversion sheet is provided with a barrier member and/or a light diffusion layer, the light scattering particles may be added to the barrier member as well as the light wavelength conversion member 11, and the light diffusion layer is also included. It may also be added in. When the layer to which the light-scattering particles are added is the outermost layer, it may be accompanied by external haze, so that the relationship between the internal haze and the external haze described above can be satisfied by controlling the surface unevenness of the outermost layer. You can

The ratio of the external haze value to the internal haze value (external haze value/internal haze value) in the light 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, light can be sufficiently diffused by the internal haze to excite the quantum dots a plurality of times.

The arithmetic average roughness (Ra) of the surfaces 10A and 10B of the light wavelength conversion sheet 10 is preferably 0.1 μm or more, and more preferably 0.5 μm or more. The reason why Ra on the surfaces 10A and 10B of the light wavelength conversion sheet 10 is preferably 0.1 μm is as follows. The light wavelength conversion sheet comes into contact with an optical plate or a lens sheet which will be described later in the backlight device. However, if the light wavelength conversion sheet and the optical plate or the lens sheet are stuck to each other, the light wavelength conversion sheet and the optical plate will be separated from each other. Since there is a possibility that a pattern called wetout that is wet with water may be formed at the interface between the optical wavelength conversion sheet and the lens sheet, the optical wavelength conversion sheet 10 and the optical plate or the lens sheet may be formed. In order to prevent sticking, Ra is more preferably 0.1 μm or more.

The definition of "Ra" is in accordance with JIS B0601:1994. Ra can be measured using, for example, a surface roughness measuring device (product name “SE-3400”, manufactured by Kosaka Laboratory Ltd.).

When a light source that emits blue light is used to irradiate a light wavelength conversion sheet 10 that includes both quantum dots that convert blue light into green light and quantum dots that convert blue light into red light, the light transmitted through the light wavelength conversion sheet 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 Is preferable, and more preferably 0.5 or more and 1.5 or less.

The ratio of the peak value of the light intensity of the red light to the peak value of the light intensity of the blue light of the transmitted light in the light wavelength conversion sheet 10 (the peak value of the light intensity of the red light/the peak value of the light intensity of the blue light) 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 It is light having a wavelength range of 590 nm or more and 750 nm or less. The light intensity of each light can be measured using a spectral radiance meter (for example, product name "CS2000", manufactured by Konica Minolta).

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

As for the thickness of the light wavelength conversion sheet 10, a cross section of the light wavelength conversion sheet 10 is photographed using a scanning electron microscope (SEM), a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), and the cross section thereof is taken. In the image, the thickness of the light wavelength conversion sheet 10 is measured at 20 locations, and the average value of the thicknesses at the 20 locations is used. Among these, it is preferable to use SEM, considering that the film thickness of the light wavelength conversion sheet 10 is on the order of μm. In the case of SEM, the acceleration voltage is preferably 30 kV and the magnification is 1000 to 7000 times, and in the case of TEM or STEM, the acceleration voltage is preferably 30 kV and the magnification is preferably 50,000 to 300,000 times.

<<Optical wavelength conversion member>>
The light wavelength conversion member is a cured product of the light wavelength conversion composition. In this case, the light wavelength conversion composition contains a quantum dot, the phosphite compound, and a polymerizable compound. Although the light wavelength conversion member 11 of this embodiment is layered, the light wavelength conversion member may not be layered. That is, the shape of the light wavelength conversion member can be appropriately changed depending on the location where the light wavelength conversion member is used.

The light wavelength conversion member 11 is a cured product of the light wavelength conversion composition, and therefore includes the quantum dots 17, a phosphite compound, and the binder resin 16 that is a cured product of a polymerizable compound. Whether or not the phosphite compound is present in the light wavelength conversion member 11 can be confirmed by the same method as the method for confirming whether or not the phosphite compound is present in the light wavelength conversion composition. .. The quantum dot 17 shown in FIG. 1 includes a first quantum dot 17A and a second quantum dot 17B having an emission band in a wavelength range different from that of the first quantum dot 17A. Further, the light wavelength conversion member 11 shown in FIG. 1 further includes light scattering particles 18. By including the light scattering particles 18, the light wavelength conversion efficiency and the internal haze can be increased. The quantum dots 17, the phosphite-based compound, and the light-scattering particles 18 included in the light wavelength conversion member 11 are the same as the quantum dots, the phosphite-based compound, and the light-scattering particles described above. The description will be omitted.

In the light wavelength conversion member 11, it is preferable that the content of the phosphorus element in the light wavelength conversion member 11 measured by X-ray fluorescence analysis is 0.05% by mass or more. When the content of the elemental phosphorus is less than 0.05% by mass, deterioration of the quantum dots may not be suppressed during the heat resistance test. The content of the phosphorus element in the light wavelength conversion member can be measured by using a fluorescent X-ray analyzer (product name “EDX-800HS”, manufactured by Shimadzu Corporation). The lower limit of the content of phosphorus element in the light wavelength conversion member 11 is more preferably 0.3 mass% or more, and the upper limit of the content of phosphorus element is preferably 2 mass% or less, 1.5 It is more preferable that the content is not more than mass %. When the content of the elemental phosphorus exceeds 2% by mass, the adhesiveness with the light transmissive substrate may be deteriorated, and aggregation or the like may occur after processing.

The phosphorus element is present around the quantum dots and in the binder resin 16, but there are cases where a phosphorus compound is contained as a ligand of the quantum dots. In this case, the quantum dots of the light wavelength conversion member are not included. By performing elemental analysis using an energy dispersive X-ray spectroscopic analyzer (EDX) attached to an electron microscope in the containing region, it is possible to grasp the presence or absence of the phosphorus element in the binder resin.

In the light wavelength conversion member 11, the content of the phosphite compound in the light wavelength conversion member 11 is preferably 1% by mass or more. When the content of the phosphite compound is less than 1% by mass, the deterioration of the quantum dots may not be suppressed during the heat resistance test. The content of the phosphite compound in the light wavelength conversion member 11 can be measured by the same method as the method for measuring the content of the phosphite compound in the light wavelength conversion composition. The lower limit of the content of the phosphite compound in the light wavelength conversion member 11 is more preferably 5% by mass or more, and the upper limit of the content of the phosphite compound is preferably 30% by mass or less, It is more preferably 20% by mass or less. When the content of the phosphite-based compound exceeds 30% by mass, the adhesion with the light transmissive base material may be deteriorated, and aggregation or the like may occur after processing.

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

<Binder resin>
The binder resin 16 is a cured product of the above-mentioned polymerizable compound, and is omitted here.

The absolute value of the refractive index difference between the light scattering particles 18 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. Either of the refractive index of the light scattering particles 18 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 member, for example, Becke method, minimum deviation method, deviation analysis, mode line method, ellipsometry method, etc. can do. As a method for measuring the refractive index of the binder resin and the light scattering particles in the light wavelength conversion member, for example, a fragment of the light scattering particle or a fragment of the host matrix is taken out from the cured light wavelength conversion member in some form. Becke's method can be used for the items. 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 Optics Laboratories or a two-beam interference microscope manufactured by Mizojiri Optical Co., Ltd.) can do.

<<Light-transmissive substrate>>
The thickness of the light transmissive substrates 12 and 13 is not particularly limited, but is 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, wrinkles and folds may occur during assembly of the light wavelength conversion sheet and during handling, and if it exceeds 300 μm, the weight and thickness of the display may be reduced. May not be suitable for The more preferable lower limit of the thickness of the light transmissive substrates 12 and 13 is 50 μm or more, and the more preferable upper limit thereof is 200 μm or less.

The thickness of the light-transmissive substrates 12 and 13 is measured by using a scanning electron microscope (SEM), a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM). Is photographed, and the thickness of the light transmissive substrates 12 and 13 is measured at 20 points in the image of the cross section, and the average value of the film thickness at the 20 points is taken.

Examples of the constituent raw materials of the light transmissive substrates 12 and 13 include polyester (eg, polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyether sulfone, polysulfone. , Polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethylmethacrylate, polycarbonate, or a thermoplastic resin such as polyurethane. As a constituent material of the light transmissive substrates 12 and 13, preferably, polyester (for example, polyethylene terephthalate or polyethylene naphthalate) is used.

The light transmissive 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 constituent materials of the same kind, or may be composed of a plurality of layers composed of layers of constituent materials of different types, depending on the application. Good.

<<Light diffusion layer>>
The light diffusion layers 14 and 15 have irregularities on the surface, and the irregularities can diffuse the light entering and exiting the light wavelength conversion sheet 10. By providing the light diffusion layers 14 and 15, the light wavelength conversion efficiency in the light wavelength conversion sheet 10 can be further improved. The light diffusion layers 14 and 15 include 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 unevenness on the surfaces of the light-diffusing layers 14 and 15 and exhibiting a light-scattering function.

The average particle diameter of the light-scattering particles in the light diffusion layers 14 and 15 is preferably 10 times or more and 20,000 times or less, more preferably 10 to 5000 times the average particle diameter of the quantum dots 17 described above. preferable. If the average particle size of the light scattering particles is less than 10 times the average particle size of the quantum dots, sufficient light diffusivity may not be obtained in the light diffusion layer, and the average particle size of the light scattering particles may be When the average particle diameter of the quantum dots exceeds 20,000 times, the light diffusion performance of the light diffusion layer is excellent, but the light transmittance of the light diffusion layer is likely 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 diffusion 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. When the average particle diameter 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 diffusibility. Need to be a lot. On the other hand, when the average particle diameter of the light scattering particles exceeds 30 μm, the light diffusion performance is excellent, but the light transmittance of the light diffusion layer is likely to be significantly reduced.

The absolute value of the refractive index difference between the light scattering particles in the light diffusion layers 14 and 15 and the binder resin is preferably 0.02 or more and 0.15 or less. When it is less than 0.02, the light diffusibility due to the refractive index of the light scattering particles is not obtained optically, and the improvement of the light wavelength conversion efficiency of the light wavelength conversion sheet may be insufficient, so that 0. When it exceeds 15, the transmittance of the light diffusion layer may be lowered. The more preferable lower limit of the refractive index difference between the light scattering particles and the binder resin is 0.03 or more, and the more preferable upper limit thereof is 0.12 or less. Either of the refractive index of the light scattering particles and the refractive index of the binder resin may be higher. The refractive index of the light scattering particles and the binder resin can be measured by the same method as the refractive index of the light scattering particles 18 and the binder resin.

The shape of the light-scattering particles in the light-diffusing layers 14 and 15 is the same as the shape of the light-scattering particles 18 in the light wavelength conversion member 11, and therefore the description thereof is omitted here. The light scattering particles in the light diffusion layers 14 and 15 are preferably chemically bonded to the binder resin from the viewpoint of firmly fixing the light scattering particles in the binder resin. This chemical bond can be realized by using light-scattering particles whose surface is modified with a silane coupling agent. The silane coupling agent is the same as the silane coupling agent described in the section of the light-scattering particles in the light wavelength conversion member, so the description 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 forming the light scattering particles is not particularly limited, and examples thereof include polyester, polystyrene, melamine resin, (meth)acrylic resin, acrylic-styrene copolymer resin, silicone resin, benzoguanamine resin, and benzoguanamine/formaldehyde condensation resin. , Polycarbonate, polyethylene, polyolefin and the like. Among them, a crosslinked acrylic resin is preferably used. The inorganic material forming the light diffusion particles is not particularly limited, and examples thereof include silica, alumina, titania, tin oxide, antimony-doped tin oxide (ATO), and inorganic oxides such as zinc oxide fine particles. Among them, silica and/or alumina are preferably used.

<Binder resin>
A cured product of a polymerizable compound can be used as the binder resin. As the polymerizable compound, the same compound as the polymerizable compound contained in the light wavelength conversion composition can be used, and therefore the description thereof is omitted here.

<<Other light wavelength conversion sheets>>
As shown in FIG. 3, the light wavelength conversion sheet may be the light wavelength conversion sheet 20 having only the light wavelength conversion member 11 (single layer structure). The light wavelength conversion sheet may be a light wavelength conversion sheet 30 including a light wavelength conversion member 11 and a light-transmissive base material 31 supporting the light wavelength conversion member 11, as shown in FIG. 4. .. By providing the light transmissive base material 31, the strength of the light wavelength conversion sheet can be increased more than that of the light wavelength conversion sheet 20.

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

<<Other light wavelength conversion sheets>>
As shown in FIGS. 5 and 6, the light wavelength conversion sheet is disposed on the light wavelength conversion member 11 and at least one surface side of the light wavelength conversion member 11, and is integrated with the light wavelength conversion member 11. The light wavelength conversion sheet 40 including the optical member 41 may be used.

<Optical member>
In the present specification, the "optical member" refers to an optical characteristic (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffractiveness, optical rotatory power, etc.). It means a member that has, and is not particularly limited as long as it is a sheet (film)-shaped or plate-shaped member having optical characteristics. Examples of the optical member include a lens sheet, an optical plate such as a light guide plate and a light diffusing plate, a reflective polarization separation sheet, and a polarizing plate. When the optical member sheets are provided on both sides of the light wavelength conversion sheet, the optical members may be optical members having different optical characteristics. In this embodiment, an example in which the optical member is a lens sheet will be described.

As shown in FIGS. 5 and 6, the optical member 41 includes a light-transmissive base material 42 and a lens layer 43 provided on one surface of the light-transmissive base material 42. As shown in FIGS. 5 and 6, the lens layer 43 includes a sheet-shaped main body portion 44, and a plurality of unit lenses 45 arranged side by side on the light output side of the main body portion 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 described later. Therefore, the description is omitted here.

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

<<Other light wavelength conversion sheets>>
The light wavelength conversion sheet may be a light wavelength conversion sheet 50 including a light wavelength conversion member 11 and overcoat layers 51 and 52 that cover both surfaces of the light wavelength conversion member 11, as shown in FIG. 7. In the present embodiment, the overcoat layers 51 and 52 are formed on both surfaces of the light wavelength conversion member 11, but if the overcoat layers are formed on at least one surface of the light wavelength conversion member, the light wavelength conversion member is converted. It may not be formed on both surfaces of the member 11. When the overcoat layer is provided on only one surface of the light wavelength conversion member, a light transmissive base material may be provided on the other surface of the light wavelength conversion member.

<Overcoat layer>
The overcoat layers 51 and 52 are layers that cover the surface of the light wavelength conversion member 11 and are made of a resin and formed by coating. The overcoat layer can be composed of, for example, a cured product of a composition containing a polymerizable compound that is polymerized by ionizing radiation or heat. Further, another layer 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 member 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 member 11, the quantum dots 17 can be protected from moisture and oxygen, and the light transmissive base material is used as the light wavelength conversion member. The thickness of the light wavelength conversion sheet can be made smaller than that provided on at least one surface of 11.

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

The 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 member 11 from being directly exposed to the atmosphere and reducing the thickness of the light wavelength conversion sheet. Is preferred. The film thickness of the overcoat layers 51 and 52 can be measured by the same method as the thickness of the light transmissive substrates 12 and 13. The lower limit of the film thickness of the overcoat layers 51, 52 is more preferably 1 μm or more, and the upper limit thereof is more preferably 50 μm or less.

It is preferable that the overcoat layers 51 and 52 have a hardness such that a vertical force is 10 μN or more and/or a horizontal force is −5 μN or less in a scratch test. When the overcoat layers 51 and 52 have such hardness, the overcoat layers 51 and 52 are dense films, and therefore have a high ability to prevent the light wavelength conversion member 11 from being exposed to the atmosphere. The vertical force and the horizontal force in the scratch test were measured using a nanoindentation device (product name “TI950 TriboIndenter”, manufactured by HYSITRON (Heiditron) Co., Ltd.) from the cross section of the overcoat layer to the inward direction of the overcoat layer. Corner:Ti037_110410(12)) is pushed in 50nm and the depth is kept constant, and the average vertical force (load) and horizontal force measured when this indenter is moved horizontally at a moving speed of 4μm/min for 30 seconds. The average value of five average values of vertical force (5 times average value) and the average value of 5 average values of horizontal force (5 times average value) obtained by repeating the scratch test five times respectively. And The larger the vertical force and the smaller 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 member 11 from being exposed to the atmosphere, the vertical force in the scratch test of the overcoat layers 51 and 52 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-mentioned hardness, but for example, a (meth)acrylate compound, an epoxy compound, a combination of an isocyanate and a polyol, a metal alkoxide, a silicon-containing resin, a water-soluble polymer, Alternatively, it can be formed by using an overcoat layer composition containing a mixture thereof. Among these, the overcoat layers 51 and 52 are zinc acrylate, a hydrolysis product of an alkoxysilane, polyvinyl alcohol, polysilazane, or these from the viewpoint of preventing the light wavelength conversion member 11 from being directly exposed to the atmosphere. It is preferably formed using a composition for an overcoat layer containing a mixture.

In the light wavelength conversion sheets 20, 30, 40, and 50, the water vapor transmission rate at 40° C. and 90% relative humidity may be 0.1 g/(m ² ·24 h) or more in the entire sheet. In the light wavelength conversion sheets 20, 30, 40 and 50, even if the oxygen transmittance at 23° C. and 90% relative humidity is 0.1 cm ³ /(m ² ·24 h·atm) or more in the entire sheet. Good. The light wavelength conversion sheet 20, 30, 40, 50 may have a water vapor transmission rate of 1 g/(m ² ·24 h) or more at 40° C. and a relative humidity of 90%, and the light wavelength conversion sheet 20, 30, The oxygen transmission rate at 40° C. and 50 at 23° C. and 90% relative humidity may be 1 cm ³ /(m ² ·24 h·atm) or more.

<<Other light wavelength conversion sheets>>
The light wavelength conversion sheet may be a light wavelength conversion sheet 60 as shown in FIG. In this case, the water vapor transmission rate and the oxygen transmission rate of the light wavelength conversion sheet 60 do not have to be within the ranges described above.

The light wavelength conversion sheet 60 shown in FIG. 8 includes the light wavelength conversion member 11, barrier members 61 and 62 provided on both surfaces of the light wavelength conversion member 11, and the light wavelength conversion member 11 side of the barrier members 61 and 62. The light diffusion layers 13 and 14 are 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 form the surfaces 60A and 60B of the light wavelength conversion sheet 60.

<Barrier member>
The barrier members 61 and 62 are members for suppressing the permeation of water and oxygen and protecting the quantum dots 17 from water and oxygen. Here, the “barrier member” in the present specification means that the member alone has a water vapor permeability of less than 0.1 g/(m ² ·24 h) at 40° C. and a relative humidity of 90%, and at 23° C. and a relative humidity. It means a member having an oxygen transmission rate of less than 0.1 cm ³ /(m ² ·24h·atm) at 90%. The barrier member includes not only a film having a single layer structure but also a film having a multilayer structure. By installing the barrier members 61 and 62 while sandwiching the light wavelength conversion member 11, it is possible to further improve the durability of the quantum dots 17. The barrier members 61 and 62 shown in FIG. 8 are provided on the light-transmissive base materials 12 and 13 and the light wavelength conversion member 11 side of the light-transmissive base materials 12 and 13, and suppress the permeation of water and oxygen. The barrier layers 63 and 64 having a function are provided.

The water vapor transmission rate (WVTR: Water Vapor Transmission Rate) of the barrier members 61 and 62 should be 1.0×10 ⁻² g/(m ² ·24 h) or less under the conditions of 40° C. and 90% relative humidity. 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).

The oxygen transmission rate (OTR: Oxygen Transmission Rate) of the barrier members 61 and 62 is 1.0×10 ⁻² cm ³ /(m ² ·24 h·atm) or less under the conditions of 23° C. and 90% relative humidity. More preferably, 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 vapor deposition layers having a function of suppressing permeation of moisture and oxygen. The vapor deposition layer is, for example, 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 vapor deposition layer has an advantage that the barrier property can be enhanced.

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

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

Regarding the film thickness of the vapor deposition layer, a cross section of the light wavelength conversion sheet 60 is photographed using a scanning electron microscope (SEM), the film thickness of the vapor deposition film is measured at 20 points in the image of the cross section, and the film at the 20 points is taken. Use the average value of thickness. Further, the vapor deposition layer may be a single layer or may be a stack of a plurality of layers. When a plurality of vapor deposition layers are laminated, each layer constituting the vapor deposition layer may be directly laminated or laminated.

<<<Method of manufacturing light wavelength conversion sheet>>>
The light wavelength conversion sheet 10 can be manufactured, for example, as follows. First, although not shown, the composition for the light diffusion layer containing the light scattering particles and the polymerizable compound is applied to one surface of the light transmissive substrate 12 and dried to apply the composition for the light diffusion layer. Form a film. Similarly, a coating film of the composition for the light diffusion layer is formed on one surface of the light transmissive substrate 13.

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

After forming the light transmissive base material 13 with the light diffusion layer 15, as shown in FIG. 9B, the side opposite to the surface of the light transmissive base material 13 with the light diffusion layer 15 on the light diffusion layer 15 side. The above-mentioned light wavelength conversion composition is applied to this surface and dried to form a coating film 19 of the light wavelength conversion composition.

After forming the coating film 19 of the light wavelength conversion composition, the surface opposite to the surface on the light diffusion layer 14 side of the light transmissive substrate 12 with the light diffusion layer 14 has the light wavelength as shown in FIG. The light transmissive substrate 12 with the light diffusing layer 14 is arranged on the coating film 19 of the light wavelength conversion composition so as to be in contact with the coating film 19 of the conversion composition. Thereby, the coating film 19 of the light wavelength conversion composition is sandwiched between the light transmissive substrates 12 and 13.

Then, as shown in FIG. 10(B), the coating film 19 of the light wavelength conversion composition is irradiated with ionizing radiation or heat is applied through the light transmissive substrate 12 to cure the polymerizable compound. Then, the light wavelength conversion member 11 is formed, and the light wavelength conversion member 11 and 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 are integrated. Thereby, the light wavelength conversion sheet 10 shown in FIG. 1 is obtained.

The light wavelength conversion sheets 20, 30, 50 can be manufactured, for example, as follows. First, a light wavelength conversion composition containing a quantum dot, the phosphite compound, the polymerizable compound and a polymerization initiator is applied onto a substrate (not shown) and dried to apply the light wavelength conversion composition. Form a film. Then, the coating film is irradiated with ionizing radiation or heated to cure the polymerizable compound, thereby forming the light wavelength conversion member 11. Then, the base material is peeled off from the light wavelength conversion member 11. As a result, the light wavelength conversion sheet 20 shown in FIG. 3 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. can get. The light wavelength conversion sheet 50 shown in FIG. 7 is obtained by applying the composition for an overcoat layer on at least one surface of the light wavelength conversion sheet 20 to form a coating film of the composition for an overcoat layer. Can be formed by curing. The light wavelength conversion sheet 50 can also be formed by the following method. First, the composition for an overcoat layer is applied to one surface of two base materials to form a coating film of the composition for an overcoat layer. After forming the coating film, the coating film of each composition for the overcoat layer is irradiated with ionizing radiation or heated to form the overcoat layer. After forming the overcoat layer, the light wavelength conversion composition is applied onto the overcoat layer formed on one of the substrates to form a coating film of the light wavelength conversion composition. Next, the other substrate is placed on the coating film of the light wavelength conversion composition so that the coating film of the light wavelength conversion composition is in contact with the overcoat layer formed on the other substrate. Then, in this state, the coating film of the light wavelength conversion composition is irradiated with ionizing radiation or heated to form a light wavelength conversion member, and the light wavelength conversion member and the overcoat layer are integrated. Let Finally, if both base materials are peeled off, the light wavelength conversion sheet 50 shown in FIG. 7 is obtained.

The light wavelength conversion sheet 40 forms the coating film of the light wavelength conversion composition by applying the light wavelength conversion composition on one surface side of the optical member 41 and drying. Then, the coating film is irradiated with ionizing radiation or heated to cure the polymerizable compound, thereby forming the light wavelength conversion member 11. As a result, the light wavelength conversion sheet 40 shown in FIG. 5 is obtained.

The light wavelength conversion sheet 60 includes the light diffusion layers 14 and 15 and the light transmissive base materials 12 and 13, and barrier layers 63 and 64 formed on one surface of the light transmissive base materials 12 and 13. If formed on the members 61 and 62, it can be formed later by the same process as the light wavelength conversion sheet 10.

The light wavelength conversion sheets 10, 20, 30, 40, 50, 60 can be used by incorporating them in a backlight device and an image display device. Hereinafter, an example in which the light wavelength conversion sheet 10 is incorporated in a backlight device and an image display device will be described. 11 is a schematic configuration diagram of an image display device including the backlight device according to the present embodiment, FIG. 12 is a perspective view of the lens sheet shown in FIG. 11, and FIG. 13 is a lens sheet II- of FIG. It is sectional drawing which followed the II line. 14, 15, and 17 are schematic configuration diagrams of another backlight device according to the present embodiment, FIG. 16 is a schematic configuration diagram of the light source shown in FIG. 15, and FIG. 18 is shown in FIG. FIG. 7 is an enlarged view of the vicinity of a light entrance surface of the optical plate.

<<< Image display device >>>
The image display device 70 shown in FIG. 11 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. 11, the surface of the display panel 120 is the display surface 70A.

The backlight device 80 illuminates the display panel 120 planarly from the back side. The display panel 120 functions as a shutter that controls 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>>
A display panel 120 shown in FIG. 11 is a liquid crystal display panel, and includes a polarizing plate 101 arranged on the light incident side, a polarizing plate 122 arranged on the light emitting side, and between the polarizing plates 121 and 122. The liquid crystal cell 103 is arranged. 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 oscillate in one direction (parallel to the transmission axis) (for example, P-polarized light component). It has a function of transmitting polarized light and absorbing a linearly polarized light component (for example, S-polarized light) vibrating in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

The liquid crystal cell 123 is configured such that a voltage can be applied to each region forming one pixel. Then, the alignment direction of the liquid crystal molecules in the liquid crystal cell 123 changes depending on whether or not a voltage is applied. As an example, the linearly polarized light component in a specific direction transmitted through the polarizing plate 121 arranged on the light incident side rotates its polarization direction by 90° when passing through the liquid crystal cell 123 to which a voltage is applied, while When passing through the liquid crystal cell 123 to which no voltage is applied, the polarization direction is maintained. In this case, depending on whether or not a voltage is applied to the liquid crystal cell 123, the linearly polarized light component that has passed through the polarizing plate 121 and vibrates in a specific direction may be transmitted to the polarizing plate 122 or may be absorbed by the polarizing plate 122 and blocked. it can. In this way, the display panel 120 is configured so that transmission or blocking of light from the backlight device 80 can be controlled for each pixel. The details of the liquid crystal display panel are described in various publicly known documents (for example, "Flat Panel Display Encyclopedia (Tatsuo Uchida, Hiraki Uchiike)," published by the 2001 Industrial Research Committee, and here are no more. The detailed description of is omitted.

<<Backlight device>>
The backlight device 80 shown in FIG. 11 is configured as an edge light type backlight device, and includes a light source 90, an optical plate 95 as a light guide plate disposed on the side of the light source 90, and a light exit side of the optical plate 95. The light wavelength conversion sheet 10 arranged on the light wavelength conversion sheet 10, the lens sheet 100 arranged on the light emission side of the light wavelength conversion sheet 10, the lens sheet 105 arranged on the light emission side of the lens sheet 100, and the light emission side of the lens sheet 105. It is provided with a reflection type polarization separation sheet 110 arranged and a reflection sheet 115 arranged on the side opposite to the light output side of the optical plate 95. The backlight device 80 includes the optical plate 95, the lens sheets 100 and 105, the reflection type polarization separation sheet 110, and the reflection sheet 115, but these sheets and the like may not be provided. In the present specification, the “light emitting side” means the side from which light in each member is emitted in the direction of emission from the backlight device.

The backlight unit 80 has a light emitting surface 80A that emits light in a planar manner. In the backlight device 80 shown in FIG. 11, the light emitting surface of the reflective polarization separation sheet 110 is the light emitting surface 80A of the backlight device 80.

The surface of the light wavelength conversion sheet 10 on the optical plate 95 side is a surface 10A (light incident surface), and the surface of the light wavelength conversion sheet 10 on the lens sheet 100 side is a 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 emitting body such as a point light emitting diode (LED) or an incandescent lamp. In the present embodiment, the light source 90 is composed of a large number of point-like light emitting elements arranged in a line on the light incident surface 95C side of the optical plate 95 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 emitter that emits light in a single wavelength range. For example, as the light source, only a blue light emitting diode that emits blue light with high color purity can be used.

<Optical plate>
The optical plate 95 as a light guide plate is formed in a quadrangular shape in 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 formed of the other main surface facing the light emitting surface 95A, and the light output surface 95A and the back surface 95B. And a side surface. Of the side surfaces, the side surface on the light source 90 side is a light incident surface 75C that receives light from the light source 90. The light that has entered the optical plate 95 from the light incident surface 95C is guided inside the optical plate in the direction (light guiding direction) that connects the light incident surface 95C and the opposite surface that faces the light incident surface 95C, and the light exit surface is formed. It is emitted from 95A.

As a material forming the optical plate 95, a material that is widely used as a material for an optical sheet incorporated in an image display device, has excellent mechanical properties, optical properties, stability, processability, and the like, and is inexpensive and available. For example, a transparent resin mainly containing one or more of acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, polyacrylonitrile, etc., or an epoxy acrylate or urethane acrylate-based reactive resin (ionizing radiation curable resin, etc.) is preferably used. Can be done. If necessary, a light diffusing material having a function of diffusing light may be added to the optical plate 75. As the light diffusing material, for example, particles made of a transparent substance such as silica (silicon dioxide), alumina (aluminum oxide), acrylic resin, polycarbonate resin, and silicone resin having an average particle diameter of 0.5 μm or more and 100 μm or less may be used. it can.

<<Lens sheet>>
The lens sheets 100 and 105 have a function of changing the traveling direction of incident light and emitting the light from the light emission side. In the present embodiment, as shown in FIG. 13, the function of changing the traveling direction of the light L3 having a large incident angle and causing the light L3 to be emitted from the light exit side, thereby concentratingly improving the brightness in the front direction (condensing function). At the same time, it has a function of reflecting the light L4 having a small incident angle and returning it to the light wavelength conversion sheet 10 side (retroreflection function). The lens sheets 100 and 105 each include a light-transmissive base material 101 and a lens layer 102 provided on one surface of the light-transmissive base material 101.

When the surfaces 10A and 10B of the light wavelength conversion sheet 10 are uneven surfaces, the light exit surface 95A of the optical plate 95 is in optical contact with a part of the surface 10A (for example, a convex portion), and 10A is preferably separated from other portions (for example, concave portions), and the light-entering surface 100A of the lens sheet 100 is in close optical contact with part of the surface 10B (for example, convex portions), and It is preferable to be separated from other portions (for example, concave portions) of 10B. In this case, the gap between the light exit surface 95A and the other part of the surface 10A and the gap between the light entrance surface 100A and the other part of the surface 10B are air layers. 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 exit surface 95A and the surface 10A and the light entrance surface 100A and the surface 10B are in optical contact. However, it is possible to prevent the light wavelength conversion sheet 10 and the optical plate 95 and the lens sheet 100 from sticking to each other, and therefore, 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 and.

<Light-transmissive substrate>
The light-transmissive base material 101 is similar to the light-transmissive base materials 12 and 13, and thus the description thereof is omitted here.

<Lens layer>
As shown in FIGS. 12 and 13, 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 output side of the main body 103.

The main body 103 functions as a sheet-shaped member that supports the unit lenses 104. As shown in FIG. 12 and FIG. 13, the unit lenses 104 are arranged on the light output side surface 103A of the main body 103 without a gap. Therefore, the light emitting surfaces 100B and 105B of the lens sheets 100 and 105 are formed by lens surfaces. On the other hand, as shown in FIG. 13, the main body 103 has, as the light incident side surface 103B facing the light output side surface 103A, a smooth surface that forms the light incident side surface of the lens layer 102.

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. 12, the unit lenses 104 extend linearly in a direction intersecting the arrangement direction AD of the unit lenses 104, and particularly linearly in the present embodiment. Further, in the present embodiment, the plurality of unit lenses 104 included in one lens sheet 100, 105 extend in parallel with each other. The longitudinal direction 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 prism shape, or may have a corrugated shape or a bowl shape such as a hemispherical shape. Specific examples of the unit lens include a unit prism, a unit cylindrical lens, and a unit microlens. 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, a triangular prism unit prism whose width becomes narrower toward the light output side will be described as the unit lens. The shape of a cross section (also called the main cutting 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 lenses 104 is a triangular shape protruding toward the light output 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 to the light emitting side.

The unit lens 104 preferably has an apex angle of 80° or more and 100° or less, and more preferably has an apex angle of about 90° from the viewpoint of improving the light utilization efficiency. However, in consideration of damage to the tip of the unit lens when the light wavelength conversion sheet is wound, the tip of the unit lens 104 may be a curved surface.

As an example, the dimensions of the lens sheets 100 and 105 can be set as follows. First, as a specific example of the unit lenses 104, the array pitch of the unit lenses 104 (corresponding to the width of the unit lenses 104 in the illustrated example) can be set to 10 μm or more and 200 μm or less. However, in recent years, high definition of the array of the unit lenses 104 is rapidly progressing, and it is preferable to set the array pitch of the unit lenses 104 to 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 to the sheet surfaces of the lens sheets 100 and 105 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. 11, the arrangement direction of the unit lenses 104 of the lens sheet 100 and the arrangement direction of the unit lenses 104 of the lens sheet 105 intersect with each other, and more specifically, are orthogonal to each other.

<Reflective polarization separation sheet>
The reflection-type polarization separation sheet 110 transmits only the first linearly polarized light component (for example, P-polarized light) of the light emitted from the lens sheet 105, and the second linearly polarized light orthogonal to the first linearly polarized light component. It has a function of reflecting a polarized component (for example, S polarized light) without absorbing it. The second linearly polarized light component reflected by the reflective polarization separation sheet 110 is reflected again and the polarization is canceled (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 polarization separation sheet 110 again. Therefore, the reflective polarization separation sheet 110 transmits the first linearly polarized light component of the re-incident light, and the second linearly polarized light component orthogonal to the first linearly polarized light component is reflected again. Hereinafter, by repeating the above process, about 70 to 80% of the light emitted from the lens sheet 105 is emitted as the light source light which has become the first linearly polarized light component. Therefore, by aligning the polarization direction of the first linearly polarized light component (transmission axis component) of the reflective polarization separation sheet 110 with the transmission axis direction of the polarizing plate 121 of the display panel 120, the light emitted from the backlight device 80 can be obtained. Are all available on the display panel 120 for image formation. Therefore, even if the light energy input from the light source 90 is the same, it is possible to form an image with higher brightness as compared with the case where the reflective polarization separation sheet 110 is not arranged, and the energy use efficiency of the light source 90 is also improved. improves. In particular, the light reflected by the reflective polarization separation sheet 110 may be wavelength-converted by the light wavelength conversion sheet 10. Therefore, the wavelength conversion efficiency of the light wavelength conversion sheet 10 can be further increased by disposing the reflective polarization separation sheet 110. Therefore, it is possible to expect further improvement in the light utilization efficiency.

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

<Reflective sheet>
The reflection sheet 115 has a function of reflecting the light leaked from the back surface 95B of the optical plate 95 and making it enter the optical plate 90 again. The reflection sheet 115 is composed of a white scattering reflection sheet, a sheet made of a material having a high reflectance such as metal, a sheet including a thin film (for example, a metal thin film) made of a material having a high reflectance as a surface layer, and the like. obtain. The reflection on the reflection 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 light wavelength conversion sheet 10 may be a direct type backlight device as shown in FIG. The backlight device 130 shown in FIG. 14 includes a light source 90, an optical plate 131 that receives light from the light source 90 and functions as a light diffusing plate, and a light wavelength conversion sheet 10 that is arranged on the light exit side of the optical plate 131. The lens sheet 100 arranged on the light exit side of the light wavelength conversion sheet 10, the lens sheet 105 arranged on the light exit side of the lens sheet 100, and the reflection type polarization separation sheet 110 arranged on the light exit side of the lens sheet 105. I have it. 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. 14, the members denoted by the same reference numerals as those in FIG. 11 are the same as the members shown in FIG. 8, and thus the description thereof will be omitted. The backlight device 130 does not include the reflection sheet 115.

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

The optical plate 131 is not particularly limited as long as it can diffuse the light from the light source 90. For example, a plate in which light diffusing particles are dispersed in a transparent material can be used. The transparent material is not particularly limited, but examples thereof include transparent resin and inorganic glass. As the transparent resin, a transparent thermoplastic resin is preferably used because it is easy to mold. The transparent thermoplastic resin is not particularly limited, but examples thereof include polystyrene resin, styrene-methyl methacrylate copolymer resin, styrene-methacrylic acid copolymer resin, styrene-maleic anhydride copolymer resin. , Methacrylic resin, acrylic resin, polycarbonate resin, ABS resin (acrylonitrile-butadiene-styrene copolymer resin), AS resin (acrylonitrile-styrene copolymer resin), polyolefin resin (polyethylene resin, polypropylene resin, etc.) and the like. .. One of these may be used, or two or more of these may be mixed and used.

<Light diffusing particles>
Examples of the light diffusing particles in the optical plate 131 include light diffusing particles generally used as a diffusing plate.

<<Other backlight devices>>
The backlight device 80 shown in FIG. 11 includes the light wavelength conversion sheet 10, but the structure of the backlight device is not particularly limited as long as it includes the light wavelength conversion member. For example, 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 as shown in FIG. 15. As shown in FIG. 16, the light source 150 includes a substrate 151, a reflecting member 152 having an opening 152A arranged on the substrate 151, and light emission arranged on the substrate 151 and inside the opening 152A of the reflecting member 152. The light emitting body 153 such as a diode and the light wavelength conversion member 154 filled in the opening 152A of the reflecting member 152 so as to cover the light emitting body 153 are provided. The light wavelength conversion member 154 is similar to the light wavelength conversion member 11 in configuration and physical properties except for the shape and arrangement of the light wavelength conversion member 11, and therefore the description thereof is omitted here. And The light wavelength conversion member 154 can be formed by filling the opening 152A of the reflection member 152 with the light wavelength conversion composition and curing the composition. When using the light source 150 having the light wavelength conversion member 154, the structure is not particularly limited as long as the light wavelength conversion member 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. 17 includes a layered light wavelength conversion member 170 arranged between the light source 90 and the optical plate 95 instead of the light wavelength conversion sheet 10. The light wavelength conversion member 170 shown in FIG. 17 is provided on the light incident surface 95C of the optical plate 95. The light wavelength conversion member 170 is the same as the light wavelength conversion member 11 in configuration and physical properties except that the light wavelength conversion member 11 is arranged at a different position. Therefore, the description thereof will be omitted here. .. The light wavelength conversion member 170 can be formed by applying the above-mentioned light wavelength conversion composition to the light incident surface 95C of the optical plate 95 and curing it.

It is considered that the reason why the quantum dots are easily deteriorated by the heat resistance test is as follows. First, 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 dot, water and oxygen are easily attached to the quantum dot, and the quantum dot is oxidized and deteriorated. It is considered that this causes the quantum dots to deteriorate due to the heat resistance test. On the other hand, in the present embodiment, since the light wavelength conversion composition and the light wavelength conversion member 11 include the phosphite compound, the heat resistance of the light wavelength conversion composition and the light wavelength conversion member 11 is improved. be able to. This is because a phosphite compound that is present in the light wavelength conversion composition and the light wavelength conversion layer 11 and is different from the ligand assists the role of the ligand even when the ligand is desorbed from the quantum dot. It is considered that this is because the deterioration of the quantum dots is suppressed, because such a function (for example, a function of substituting for the ligand by binding to the quantum dot instead of the ligand and/or a function of trapping oxygen) is exerted. .. Even if it is a phosphorus-based compound, since the phosphite-based compound does not contain hydrogen that functions as an acid, a compound that contains hydrogen that functions as an acid, such as a quantum dot, is more preferable than an acidic phosphate ester. Highly effective in suppressing deterioration.

According to the present embodiment, deterioration of the quantum dots 17 can be suppressed by the phosphite-based compound present in the light wavelength conversion member 11, so that in the light wavelength conversion sheet 10, 20, 30, 40, 50, 60, the barrier. The member can be omitted, and the dot-like luminance defect can be suppressed even when the barrier member is used. That is, in the light wavelength conversion sheets 10, 20, 30, 40, and 50, deterioration of the quantum dots 17 can be suppressed by the phosphite-based compound present in the light wavelength conversion member 11, so the barrier member can be omitted. it can. Further, in the light wavelength conversion sheet 60 including the barrier members 61 and 62, the phosphite-based compound present in the light wavelength conversion member 11 can suppress the deterioration of the quantum dots 17, so that even if the barrier member 61, Even when a pinhole or a crack is generated in 62 and moisture or oxygen enters from the pinhole or the crack, the dot-like luminance defect can be suppressed. Further, since deterioration of the quantum dots 17 can be suppressed by the phosphite-based compound present in the light wavelength conversion member 11, in the light wavelength conversion sheets 10, 20, 30, 40, 50, 60, the peripheral portions 10C, 20A, 30A. , 40A, 50A, 60C, the deterioration of the quantum dots 17 can be suppressed.

In the light wavelength conversion sheets 10, 20, 30, 40, and 50, since the phosphite-based compound present in the light wavelength conversion member 11 can suppress the deterioration of the quantum dots 17, no barrier member is provided. Accordingly, the quality of the light wavelength conversion sheet can be improved easily by simplifying the process of the light wavelength conversion sheet, and the light wavelength conversion sheet can be thinned.

In the light wavelength conversion sheet 40, since the light wavelength conversion member 11 and the optical member 41 are integrated, compared to the case where the light wavelength conversion sheet and the optical member are separately arranged, the light wavelength conversion member 11 and the optical member 41 are simplified and thin. A backlight device can be obtained. That is, when the light wavelength conversion sheet and the optical member are separately arranged, since there is an air interface between the light wavelength conversion sheet and the optical member, a relatively large gap is formed in the backlight device. It costs. On the other hand, in the present embodiment, since the light wavelength conversion member 11 and the optical member 41 are integrated, there is no air interface between the light wavelength conversion member 11 and the optical member 41. Thereby, a simplified and thin backlight device can be obtained.

A light emitting body such as a light emitting diode also generates heat when emitting light. Therefore, normally, when the light wavelength conversion member is incorporated in the light source or when the light wavelength conversion member is arranged in a position close to the light source, the light wavelength conversion member is covered to suppress the deterioration of the quantum dots. A barrier member is required. On the other hand, in the present embodiment, the heat resistance of the light wavelength conversion members 154 and 170 can be improved by the phosphite-based compound present in the light wavelength conversion members 154 and 170. The deterioration of the quantum dots 17 can be suppressed without covering 170 with the barrier member. Accordingly, the light wavelength conversion member 154 can be incorporated in the light source 150, or the light wavelength conversion member 170 can be arranged at a position close to the light source 90.

Conventionally, on the light output side of the light wavelength conversion sheet, the light wavelength-converted by the quantum dots emitted from the light wavelength conversion sheet is condensed, and the light not wavelength-converted by the light wavelength conversion sheet is converted into the light wavelength conversion sheet. It is considered to arrange a lens sheet to be returned to the side to increase the light wavelength conversion efficiency. However, the light wavelength conversion efficiency is not sufficient only by disposing such a lens sheet, and further improvement of the light wavelength conversion efficiency is desired. According to this 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 a straight traveling property, the light emitted from the light wavelength converting sheet enters the light wavelength converting sheet, is not wavelength-converted by the quantum dots, and has a straight traveling property. There is. Here, when the external haze value of the light wavelength conversion sheet is high, the wavelength-unconverted light having straightness is refracted on the surface of the light wavelength conversion sheet, and the wavelength-unconverted light emitted from the light wavelength conversion sheet is Has many components with a large emission angle. On the other hand, in a lens sheet having a condensing function and a retroreflective function, the smaller the angle of incidence on the lens sheet, the easier the retroreflection of the lens sheet. That is, there is a tendency that light having a larger incident angle on the lens sheet is more likely to pass through the lens sheet. In the present embodiment, since the external haze value is smaller than the internal haze value in the light wavelength conversion sheet 10, even if the light whose wavelength is not converted is refracted on the surface of the light wavelength conversion sheet 10, the light is emitted. The light can be emitted in a state where the angle is small, and thus, in the light that has not been wavelength-converted and is emitted from the light wavelength conversion sheet 10, a component having a small emission angle can be increased. Therefore, since the light emitted from the light wavelength conversion sheet without wavelength conversion can be retroreflected by the lens sheet 100 and returned to the light wavelength conversion sheet 10 side, the opportunity for wavelength conversion increases. Further, since the internal haze value is larger than the external haze value, light is scattered a plurality of times inside the light wavelength conversion sheet, so that the optical path length is extended and the chance of wavelength conversion is further increased. Thereby, the light wavelength conversion efficiency can be improved. Since the quantum dots 17 emit isotropic light, the light whose wavelength is converted by the quantum dots 17 is directed in various directions, and when reaching the surface of the light wavelength conversion sheet 10, the surface of the light wavelength conversion sheet is further increased. The light is refracted at, and the light whose wavelength is converted becomes light with a large angle and is easily emitted from the light wavelength conversion sheet. Therefore, the wavelength-converted light relatively easily passes through the lens sheet 100.

In the above description, the external haze value is used to represent the light diffusion property (external diffusion property) on the surface of the light wavelength conversion sheet for the following reason. 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 goniophotometer 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 that deviates from the incident light by 2.5° or more is measured as haze, but if the transmitted light is less than 2.5° with respect to the incident light, it is regarded as haze. Not measured. In this way, as haze, transmitted light of less than 2.5° with respect to incident light is not measured, but as described above, light having a large incident angle to the lens sheet, that is, transmitted light having a large outgoing angle in the light wavelength conversion sheet is not measured. Since it becomes a problem, it is important how much the transmitted light deviated by 2.5° or more from the incident light less than 2.5°. Therefore, the light diffusion characteristics of the light wavelength conversion sheet can be represented by the size of the haze value of the light wavelength conversion sheet without measuring the light intensity at each angle of the transmitted light by the goniophotometer. On the other hand, since it is necessary to consider that light is refracted on the surface of the light wavelength conversion sheet and the emission angle becomes large, in order to represent the light diffusion characteristics on the surface of the light wavelength conversion sheet, the external haze is used. Values were used.

According to this embodiment, the light wavelength conversion member 11 includes the light scattering particles 18, so that 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 17A, and blue light is converted into red light as the second quantum dot 17B. When the light wavelength conversion sheet including the quantum dots is irradiated with blue light, the chromaticity x and y can be increased as compared with the light wavelength conversion sheet that does not include the light scattering particles, and white light or a color close to white is obtained. You can get a taste of light.

According to the present embodiment, the light wavelength conversion member sheet 11 includes the light scattering particles 18, so that the green light emission can be preferentially enhanced over the red light emission. The reason for this is not clear, but the light-scattering particles seem to interfere with the 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 the green light emission, which was originally deactivated by the energy transfer, reaches the light emission process without being deactivated, resulting in an increase in green light emission.

The present invention will be described below in detail with reference to Examples, but the present invention is not limited to these descriptions.

<Preparation of light wavelength conversion composition>
First, each component was mixed so as to have the composition shown below to obtain a light wavelength conversion composition.

(Light wavelength conversion composition 1)
Epoxy acrylate (Product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Trisnonylphenyl phosphite (phosphite, product name "JP-351", manufactured by Johoku Chemical Industry 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): 0.2 parts by mass red emission quantum Dot (product name "CdSe/ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone) , Product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 2)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 79.4 parts by mass Trisnonylphenyl phosphite (phosphite, product name "JP-351", manufactured by Johoku Chemical Industry 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): 0.2 parts by mass red emission quantum Dot (product name "CdSe/ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass Alumina particles (light scattering particles, product name "DAM-03", manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 4 µm): 10 parts by mass. Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184" manufactured by BASF Japan): 0.2 parts by mass

(Light wavelength conversion composition 3)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 79.4 parts by mass Trisnonylphenyl phosphite (phosphite, product name "JP-351", manufactured by Johoku Chemical Industry Co., Ltd.) : 20 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): 0.2 parts by mass red emission quantum Dot (product name "CdSe/ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone) , Product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 4)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 94.4 parts by mass Trisnonylphenylphosphite (phosphorous ester, product name "JP-351", manufactured by Johoku Chemical Industry Co., Ltd.) : 5 parts by mass/green light emitting quantum dot (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 light emitting quantum Dot (product name "CdSe/ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone) , Product name “Irgacure (registered trademark) 184”, manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 5)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Triphenyl phosphite (phosphite, product name "JP-360", manufactured by Johoku Chemical Co., Ltd.): 10 parts by mass/green light emitting quantum dot (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 light emitting quantum dot (Product name "CdSe/ZnS 610", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, Product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 6)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass. Phenyldiisodecyl phosphite (phosphite, product name "Chelex D", manufactured by SC Organic Chemical Co., Ltd.): 10 Parts by mass/green light emitting quantum dots (product name “CdSe/ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass/red light emitting 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 radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product Name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 7)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Tris(2-ethylhexyl) phosphite (phosphite ester, product name "JP-308E", Johoku Chemical Industry Co., Ltd. Company): 10 parts by mass green light emitting quantum dots (product name "CdSe/ZnS 530", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass. Red light emitting 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 radical polymerization initiator (1-hydroxy) Cyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 8)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass bis(decyl)pentaerythritol diphosphite (phosphite, product name "JPE-10", Johoku Chemical Co., Ltd. (Manufactured by Kogyo Co., Ltd.): 10 parts by mass green light emitting quantum dots (product name "CdSe/ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-radical polymerization initiator (1- Hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 9)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Tetraphenyldipropylene glycol diphosphite (phosphorous acid ester, product name "JPP-100", Johoku Chemical Industry Co., Ltd. Company): 10 parts by mass green light emitting quantum dots (product name "CdSe/ZnS 530", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass. Red light emitting 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 radical polymerization initiator (1-hydroxy) Cyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 10)
Epoxy acrylate (Product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Trioleyl phosphite (phosphite, product name "Chelex OL", manufactured by SC Organic Chemistry): 10 Parts by mass/green light emitting quantum dots (product name “CdSe/ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass/red light emitting 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 radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product Name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 11)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Di-2-ethylhexyl hydrogen phosphite (phosphonate ester, product name "Chelex H-8", SC organic Chemical company): 10 parts by mass, green light emitting quantum dots (product name "CdSe/ZnS 530", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-radical polymerization initiator (1- Hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 12)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 79.4 parts by mass-Di-2-ethylhexyl hydrogen phosphite (phosphonate ester, product name "Chelex H-8", SC organic Chemical company): 10 parts by mass, green light emitting quantum dots (product name "CdSe/ZnS 530", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-alumina particles (light scattering particles , Product name “DAM-03”, manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 4 μm): 10 parts by mass radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name “Irgacure (registered trademark) 184”, BASF Japan Manufactured by the company): 0.2 parts by mass

(Light wavelength conversion composition 13)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 79.4 parts by mass-Di-2-ethylhexyl hydrogen phosphite (phosphonate ester, product name "Chelex H-8", SC organic Chemical Co., Ltd.: 20 parts by mass, green light emitting quantum dots (product name “CdSe/ZnS 530”, SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-radical polymerization initiator (1- Hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 14)
Epoxy acrylate (Product name "Unidick V-5500", manufactured by DIC): 94.4 parts by mass Di-2-ethylhexyl hydrogen phosphite (phosphonate, product name "Chelex H-8", SC organic Chemical Co., Ltd.: 5 parts by mass green light emitting quantum dots (product name “CdSe/ZnS 530”, SIGMA-ALDRICH Co., core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts 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): 0.2 parts by mass-radical polymerization initiator (1- Hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 15)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Diphenyl hydrogen phosphite (phosphonate ester, product name "JP-260", manufactured by Johoku Chemical Industry Co., Ltd.): 10 Parts by mass/green light emitting quantum dots (product name “CdSe/ZnS 530”, manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass/red light emitting 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 radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product Name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 16)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass Dioleyl hydrogen phosphite (phosphonate ester, product name "Chelex H-18D", manufactured by SC Organic Chemical Co., Ltd. ): 10 parts by mass/green light emitting quantum dot (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 light emission Quantum dot (Product name "CdSe/ZnS 610", SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 5.2 nm): 0.2 parts by mass Radical polymerization initiator (1-hydroxycyclohexylphenyl Ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 17)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 99.4 parts by mass. Green light emitting quantum dots (product name "CdSe/ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell. : ZnS, average particle size 3.3 nm: 0.2 parts by mass red light emitting 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 Radical polymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 18)
Epoxy acrylate (Product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass 2-Ethylhexyl acid phosphate (acid phosphate, product name "Pholex A-8", SC Organic Chemical Co., Ltd. Made): 10 parts by mass, green light emitting quantum dots (product name "CdSe/ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red Luminescent 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 radical polymerization initiator (1-hydroxycyclohexyl) Phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

(Light wavelength conversion composition 19)
Epoxy acrylate (product name "Unidick V-5500", manufactured by DIC): 89.4 parts by mass n-octyl acid phosphate (acid phosphate, product name "Pholex A-8N", SC Organic Chemical Co., Ltd. Made): 10 parts by mass, green light emitting quantum dots (product name "CdSe/ZnS 530", manufactured by SIGMA-ALDRICH, core: CdSe, shell: ZnS, average particle size 3.3 nm): 0.2 parts by mass, red Luminescent 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 radical polymerization initiator (1-hydroxycyclohexyl) Phenyl ketone, product name "Irgacure (registered trademark) 184", manufactured by BASF Japan Ltd.): 0.2 parts by mass

<Preparation of composition for overcoat layer>
Each component was mixed 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 Shokubai Co., Ltd.): 30 parts by mass-Methanol: 70 parts by mass-Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184," (Manufactured by BASF Japan): 1 part by mass

(Composition 2 for overcoat layer)
-A mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate (product name "Aronix (registered trademark) M-403", manufactured by Toagosei Co., Ltd.): 30 parts by mass, methanol: 70 parts by mass, photopolymerization initiator (1 -Hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass

<Preparation of composition for light diffusion layer>
The components were blended so that the composition shown below was obtained to obtain a light diffusion layer composition 1.
(Composition 1 for light diffusion layer)
-Pentaerythritol triacrylate: 99 parts by mass-Light scattering particles (crosslinked polystyrene resin beads, product name "SBX-4", manufactured by Sekisui Plastics Co., Ltd., average particle diameter 4 µm): 158 parts by mass-Photopolymerization initiator (1-hydroxycyclohexyl phenyl ketone, product name "Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.): 1 part by mass-solvent (methyl isobutyl ketone:cyclohexanone=1:1 (mass ratio)): 170 parts by mass

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

Next, the light wavelength conversion composition 1 was applied to the surface opposite to the light diffusion layer side surface of one of the PET substrates with the light diffusion layer and dried at 80° C. to form a coating film. Then, the other PET base material with a light diffusion layer was laminated on the coating film so that the surface on the side opposite to the surface on the light diffusion layer side of the other PET base material with a light diffusion layer was in contact with the coating film. In this state, the coating film is cured by irradiating with ultraviolet light so that the integrated light amount becomes 500 mJ/cm ^2, and a light wavelength conversion member having a film thickness of 100 μm is formed. It was integrated with a PET substrate with a diffusion layer. Thereby, the light wavelength conversion sheet according to Example 1 was obtained.

<Example 2>
In Example 2, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 2 was used instead of the light wavelength conversion composition 1.

<Example 3>
In Example 3, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 3 was used instead of the light wavelength conversion composition 1.

<Example 4>
In Example 4, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 4 was used instead of the light wavelength conversion composition 1.

<Example 5>
In Example 5, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 5 was used instead of the light wavelength conversion composition 1.

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

<Example 7>
In Example 7, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 7 was used instead of the light wavelength conversion composition 1.

<Example 8>
In Example 8, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 8 was used instead of the light wavelength conversion composition 1.

<Example 9>
In Example 9, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 9 was used instead of the light wavelength conversion composition 1.

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

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

<Example 12>
In Example 12, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 12 was used instead of the light wavelength conversion composition 1.

<Example 13>
In Example 13, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 13 was used instead of the light wavelength conversion composition 1.

<Example 14>
In Example 14, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 14 was used instead of the light wavelength conversion composition 1.

<Example 15>
In Example 15, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 15 was used instead of the light wavelength conversion composition 1.

<Example 16>
In Example 16, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 16 was used instead of the light wavelength conversion composition 1.

<Example 17>
The light wavelength conversion composition 1 was applied to one surface of a polyethylene terephthalate (PET) substrate (product name “Lumirror T60”, manufactured by Toray Industries, Inc.) having a thickness of 50 μm 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 amount was 500 mJ/cm ² . Finally, the PET base material was peeled off to obtain a light wavelength conversion sheet according to Example 17 having only a light wavelength conversion member with a film thickness of 100 μm.

<Example 18>
The composition 1 for overcoat layer was applied to one surface of the light wavelength conversion sheet (light wavelength conversion member) produced in Example 17 to form a coating film. Then, the coating film was cured by irradiating it with ultraviolet rays so that the integrated light amount was 500 mJ/cm ² , to obtain an overcoat layer having a film thickness of 5 μm. Next, similarly, the composition 1 for the overcoat layer was applied to the other surface of the light wavelength conversion member to form a coating film. Then, the coating film was cured by irradiating it with ultraviolet rays so that the integrated light amount was 500 mJ/cm ² , to obtain an overcoat layer having a film thickness of 5 μm. Thereby, a light wavelength conversion sheet including the light wavelength conversion member and the overcoat layers formed on both surfaces of the light wavelength conversion member was obtained.

<Example 19>
In Example 19, a light wavelength conversion sheet was produced in the same manner as in Example 18 except that the composition 2 for overcoat layer was used instead of the composition 1 for overcoat layer.

<Example 20>
A 100 μm-thick polyethylene terephthalate (PET) substrate (product name “Lumirror T60”, manufactured by Toray Industries, Inc.) was evenly coated with a prism layer composition containing urethane acrylate to form a prism layer composition. A coating film was formed to form a prism sheet laminate. Then, the laminate for prism sheet has a traveling speed so that a molding die having a concave shape opposite to the desired shape of the unit prism and the coating film of the composition for lens layer is on the molding die side. It is supplied at a rate of 20 m/min to form the shape of the unit prism on the coating film of the composition for prism layer by a molding die, and at the same time, the coating film of the composition for prism layer is exposed to light such as ultraviolet rays through the PET base material. Irradiation was carried out to cure the coating film of the composition for prism layer. Finally, the cured coating film of the prism layer composition was peeled off from the molding die 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 layer is arranged in a sheet-like body portion side by side on the body portion, and each extends in a direction intersecting with the arrangement direction, has an apex angle of 90°, a width of 47 μm, and a height. Had a plurality of triangular prism-shaped unit prisms having a size of 30 μm.

Next, the light wavelength conversion composition 1 was applied to the surface of the prism sheet on the side opposite to the prism layer side of the PET substrate, and dried at 80° C. to form a coating film. Then, the coating film was cured by irradiating it with ultraviolet rays so that the integrated light amount was 500 mJ/cm ² , thereby forming a light wavelength conversion member having a film thickness of 100 μm integrated with the prism sheet. Thereby, the light wavelength conversion sheet according to Example 20 was obtained.

<Example 21>
First, two barrier members were manufactured by the following method. In a high-frequency sputtering device, by applying high-frequency power having a frequency of 13.56 MHz and power of 5 kW to electrodes, a discharge is generated in the chamber, and polyethylene terephthalate as a light-transmissive substrate having a size of 7 inches and a thickness of 50 μm. On one surface of a (PET) substrate (product name “Lumirror T60”, manufactured by Toray Industries, Inc.), a silica vapor deposition layer made of a target substance (silica) having a thickness of 50 nm and a refractive index of 1.46 was formed. As a result, two barrier members each having a silica vapor deposition layer formed on one surface of the PET substrate were formed.

Next, the composition 1 for a light diffusion layer was applied to the surface of both barrier members opposite to the surface on the silica vapor deposition layer side to form a coating film. Next, the formed coating film was dried by circulating dry air at 80° C. for 30 seconds to evaporate the solvent in the coating film. After that, the coating film was cured by irradiating with ultraviolet rays so that the integrated light amount was 500 mJ/cm ² , to form a light diffusion layer having a film thickness of 10 μm, and thus a barrier member with a light diffusion layer was formed.

Next, the light wavelength conversion composition 1 was applied to the silica vapor deposition layer side of one of the barrier members with a light diffusion layer and dried at 80° C. to form a coating film. Then, the other barrier member with a light diffusion layer was laminated on the surface of the silica vapor deposition layer of the barrier member with a light diffusion layer in the coating film so that the silica vapor deposition layer was in contact with the other barrier member. In this state, the coating film is cured by irradiating with ultraviolet rays so that the integrated light amount becomes 500 mJ/cm ² , thereby forming a light wavelength conversion member having a film thickness of 100 μm, which is in close contact with both barrier members with a light diffusion layer. did. Thereby, the light wavelength conversion sheet according to Example 21 was obtained.

<Comparative Example 1>
In Comparative Example 1, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 17 was used instead of the light wavelength conversion composition 1.

<Comparative example 2>
In Comparative Example 2, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 18 was used instead of the light wavelength conversion composition 1.

<Comparative example 3>
In Comparative Example 3, a light wavelength conversion sheet was produced in the same manner as in Example 1 except that the light wavelength conversion composition 19 was used instead of the light wavelength conversion composition 1.

<Comparative example 4>
In Comparative Example 4, a light wavelength conversion sheet was produced in the same manner as in Example 17, except that the light wavelength conversion composition 17 was used instead of the light wavelength conversion composition 1.

<Comparative Example 5>
In Comparative Example 5, a light wavelength conversion sheet was produced in the same manner as in Example 17, except that the light wavelength conversion composition 18 was used instead of the light wavelength conversion composition 1.

<Comparative example 6>
In Comparative Example 6, a light wavelength conversion sheet was produced in the same manner as in Example 17, except that the light wavelength conversion composition 19 was used instead of the light wavelength conversion composition 1.

<Comparative Example 7>
In Comparative Example 7, a light wavelength conversion sheet was produced in the same manner as in Example 18 except that the light wavelength conversion composition 17 was used instead of the light wavelength conversion composition 1.

<Comparative Example 8>
In Comparative Example 8, a light wavelength conversion sheet was produced in the same manner as in Example 18 except that the light wavelength conversion composition 18 was used instead of the light wavelength conversion composition 1.

<Comparative Example 9>
In Comparative Example 9, a light wavelength conversion sheet was produced in the same manner as in Example 18 except that the light wavelength conversion composition 19 was used instead of the light wavelength conversion composition 1.

<Comparative Example 10>
In Comparative Example 10, a light wavelength conversion sheet was produced in the same manner as in Example 20 except that the light wavelength conversion composition 17 was used instead of the light wavelength conversion composition 1.

<Comparative Example 11>
In Comparative Example 11, a light wavelength conversion sheet was produced in the same manner as in Example 20 except that the light wavelength conversion composition 18 was used instead of the light wavelength conversion composition 1.

<Comparative Example 12>
In Comparative Example 12, a light wavelength conversion sheet was produced in the same manner as in Example 20 except that the light wavelength conversion composition 19 was used instead of the light wavelength conversion composition 1.

<Comparative Example 13>
In Comparative Example 13, a light wavelength conversion sheet was produced in the same manner as in Example 21 except that the light wavelength conversion composition 17 was used instead of the light wavelength conversion composition 1.

<Comparative Example 14>
In Comparative Example 14, a light wavelength conversion sheet was produced in the same manner as in Example 21 except that the light wavelength conversion composition 18 was used instead of the light wavelength conversion composition 1.

<Comparative Example 15>
In Comparative Example 15, a light wavelength conversion sheet was produced in the same manner as in Example 21 except that the light wavelength conversion composition 19 was used instead of the light wavelength conversion composition 1.

<Measurement of phosphorus compound content>
In the light wavelength conversion sheets according to the above-mentioned examples and comparative examples, the content of the sulfur element contained in the light wavelength conversion member was measured by using a fluorescent X-ray analyzer (product name ““EDX-800HS””, manufactured by Shimadzu Corporation). Was measured.

<Measurement of water vapor transmission rate and oxygen transmission rate>
In the light wavelength conversion sheets according to the above-mentioned examples and comparative examples, the water vapor transmission rate and the oxygen transmission rate were measured. The water vapor transmission rate of the light wavelength conversion sheet is 40° C. and 90% relative humidity according to JIS K7129:2008, using a water vapor transmission rate measuring device (product name “PERMATRAN-W3/31”, manufactured by MOCON). It was measured under the conditions of. Further, the oxygen transmittance of the light wavelength conversion sheet is 23° C. using a 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 humidity of 90%.

<Adhesion evaluation (1)>
In the light wavelength conversion sheets according to Examples 1 to 17, 20, and 21 and Comparative Examples 1 to 3 and 10 to 15, the adhesion between the light wavelength conversion layer and the PET substrate was evaluated as follows. Specifically, first, a test piece having a width of 25 mm was cut out from each of the initial light wavelength conversion sheets by using a cutter so that the peripheral edge portion did not float. Then, the obtained test piece was fixed to a chucking jig attached to a tensile tester (equipment name “Tensilon”, manufactured by A&D (A&D) Co.), and the surface of the test piece at room temperature. Is 0°, the PET base material is pulled in a direction of a peeling angle of 180° with respect to this surface at a pulling speed of 0.3 m/min, and the PET base material is peeled off from the light wavelength conversion member. The adhesion with the PET substrate was evaluated. When the peel strength, which is the force required to peel off the PET substrate from the light wavelength conversion member, can be measured, the peel strength was measured. In addition, the "base material fracture" shown in Table 1 and Table 2 means that the adhesiveness between the light wavelength conversion member and the PET base material is excellent, and when the PET base material is peeled from the light wavelength conversion member, peeling occurs. It means a state in which the PET substrate was broken without being able to do it.

<Adhesion evaluation (2)>
In the light wavelength conversion sheets according to Examples 18 and 19 and Comparative Examples 7 to 9, the adhesion between the light wavelength conversion layer and the overcoat layer was evaluated by an adhesion test by a cross cut method. Specifically, with respect to the light wavelength conversion sheets according to Examples 18 and 19 and Comparative Examples 7 to 9, 100 square regions (squares) each having a side of 1 cm were formed according to JIS K5600-5-6. As shown in the figure, a notch is made in the light wavelength conversion sheet with a cutter knife, and industrial 100 mm cellophane tape (registered trademark) manufactured by Nichiban Co., Ltd. is attached as an adhesive tape to all 100 square areas, and then pulled up directly above. The presence or absence of peeling of the overcoat layer was examined. In addition, the value of the adhesiveness evaluation (2) in Table 1 and Table 2 means (the number of squares which did not peel off)/(total of squares).

<Brightness retention rate measurement after heat resistance test>
In the light wavelength conversion sheets according to the above-mentioned Examples and Comparative Examples, a heat resistance test was conducted by leaving the light wavelength conversion sheet in an environment of 80° C. for 500 hours, and a heat resistance test against luminance before heat resistance test in the light wavelength conversion sheet was performed. The retention rate of luminance after that was examined. Specifically, first, a backlight device of Kindle Fire (registered trademark) HDX7 was prepared, and the light wavelength conversion sheet before the heat resistance test was incorporated into this backlight device. This backlight device was equipped with 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 1 to 19 and 21, and Comparative Examples 1 to 9 and 13 to 15, the light guide plate is arranged so that the blue light emitting diode side becomes the light incident surface, and Examples 1 to 19 are arranged on the light exit surface of the light guide plate. , 21, and the light wavelength conversion sheets according to Comparative Examples 1 to 9 and 13 to 15, the first prism sheet, and the second prism sheet were arranged in this order to obtain a backlight device. The second prism sheet was arranged such that the arrangement direction of the unit prisms was orthogonal to the arrangement direction of the unit prisms of the first prism sheet.

In Example 20 and Comparative Examples 10 to 12, the light guide plate is arranged such that the blue light emitting diode side is the light entrance surface, and the prism surface of the prism sheet is on the light exit surface of the light guide plate. The light wavelength conversion sheet according to Example 20 and Comparative Examples 10 to 12 and the second prism sheet 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 sheet in the light wavelength conversion sheets according to Example 20 and Comparative Examples 10 to 12. In this way, backlight devices incorporating the light wavelength conversion sheets according to Example 20 and Comparative Examples 10 to 12 were obtained.

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

Then, 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 above. In this state, in the same manner as 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) through the other surface of the light wavelength conversion sheet. The brightness of the light emitted from (1) was measured from the thickness direction of the light wavelength conversion sheet using a spectral radiance meter (product name "CS2000", manufactured by Konica Minolta) under the condition of a measurement angle of 1°.

From these measured luminances, the maintenance ratio of the luminance after the heat resistance test to the luminance before the heat resistance test was obtained. The brightness maintenance ratio is A, the brightness of light emitted from the light emitting surface of the backlight device before the heat resistance test is B, and the brightness of light emitted from the light emitting surface of the backlight device after the heat resistance test. Was determined as C and calculated by the following formula.
A=C/B×100

<Evaluation of dot-like luminance defects>
Using the above-mentioned backlight device incorporating the light wavelength conversion sheet after the heat resistance test according to the above-mentioned examples and the above-mentioned comparative examples, whether there is a point-like luminance defect on the light-emitting surface during light emission in the backlight device. It was visually observed and evaluated. The evaluation criteria are as follows.
◯: No dot-like luminance defect was confirmed.
B: Several spot-like luminance defects were confirmed.
X: Many point-like luminance defects were confirmed.

<Measurement of deterioration width of peripheral edge of light wavelength conversion sheet>
Using the above backlight device incorporating the light wavelength conversion sheet after heat resistance test according to Examples and Comparative Examples, the luminance distribution on the light emitting surface during light emission in the backlight device, from the thickness direction of the light wavelength conversion sheet. The measurement was performed using a 2D color luminance meter (product name "UA-200", manufactured by Topcon Technohouse). Then, from the measured luminance distribution of the light emitting surface, the position of the light emitting surface where the luminance is 80% of the luminance of the central portion of the light emitting surface (80% luminance position) is obtained, and the position is closest to the 80% luminance position on the light emitting surface. The shortest distance from the edge to the 80% luminance position was determined. Then, this shortest distance was randomly obtained at 20 locations, and the average value of the shortest distances at these 20 locations was used as the deterioration width of the peripheral portion of the light wavelength conversion sheet.

The results are shown below in Tables 1 to 4.

The results will be described below. As can be seen from Table 3 and Table 4, in the light wavelength conversion sheets according to Examples 1 to 20, since the phosphite-based compound is used, Comparative Examples 1, 4, 7, which do not use the phosphorus-based compound itself, The luminance retention ratio was higher than that of the light wavelength conversion sheet according to No. 10 or the light wavelength conversion sheet according to Comparative Examples 2, 3, 5, 6, 8, 9, 11, or 12 using the acid phosphate. Further, since the phosphite-based compound is used in the light wavelength conversion sheet according to Example 21, a comparison using the light-wavelength conversion sheet according to Comparative Example 13 not using the phosphorus-based compound itself and the acidic phosphate ester is performed. The luminance retention ratio was higher than that of the light wavelength conversion sheets according to Examples 14 and 15. This is because the light wavelength conversion compositions 1 to 16 and the cured products thereof have high heat resistance, and the phosphite-based compound can suppress the deterioration of the quantum dots, and moreover the deterioration suppressing effect of the quantum dots is higher than that of the acidic phosphate ester. It means high.

Since no barrier member was used in the light wavelength conversion sheets according to Examples 1 to 20 and Comparative Examples 1 to 12, no dot-like luminance defect was confirmed. Further, in the light wavelength conversion sheet according to Example 21, although the barrier member was used, since the phosphite-based compound was used, the dot-like luminance defect was not confirmed. On the other hand, in the light wavelength conversion sheet according to Comparative Example 13 not using the phosphorus-based compound itself and Comparative Examples 14 and 15 using the acidic phosphoric acid ester, dot-like luminance defects were confirmed. This means that the phosphite-based compound can suppress the deterioration of the quantum dots and has a higher effect of suppressing the deterioration of the quantum dots than the acidic phosphoric acid ester.

In the light wavelength conversion sheets according to Examples 1 to 21, since the phosphite-based compound was used, the deterioration of the peripheral portion was suppressed. This means that the phosphite compound has an effect of suppressing deterioration of the quantum dots. On the other hand, in the light wavelength conversion sheets according to Comparative Examples 1 to 12 in which the phosphite-based compound was not used, the result of the deterioration of the peripheral portion was 0 mm, which means that the light wavelength conversion member was exposed. Therefore, after the heat resistance test, the quantum dots were deteriorated as a whole, and there was almost no difference in luminance between the peripheral portion and the central portion. Further, in the light wavelength conversion sheets according to Comparative Examples 13 to 15, the deterioration of the central portion was relatively suppressed by the barrier member, but the deterioration of the peripheral portion was not suppressed.

In the light wavelength conversion sheets according to Examples 1 to 12, 14 to 16, 20, and 21, the content of phosphorus element in the light wavelength conversion layer measured by fluorescent X-ray analysis was 2% by mass or less. The adhesiveness to the PET substrate was superior to that of Example 13 in which the phosphorus element content in the light wavelength conversion layer measured by fluorescent X-ray analysis exceeded 2 mass %. In addition, in the light wavelength conversion sheets according to Examples 18 and 19, since the content of the phosphorus element in the light wavelength conversion layer measured by fluorescent X-ray analysis was 2% by mass or less, it was confirmed that It had excellent adhesion.

The total haze value of the light wavelength conversion sheet according to Example 1 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%. In both light wavelength conversion sheets, since the external haze value is smaller than the internal haze value, both have high brightness regardless of before and after the durability test, but the light wavelength conversion sheet according to Example 1 and the example. Comparing the light wavelength conversion sheets according to Example 2, the light wavelength conversion sheet according to Example 2 had higher brightness regardless of before and after the heat resistance test. This is because the light wavelength conversion sheet according to Example 2 contains alumina particles as the light scattering particles, so that the internal haze value of the light wavelength conversion sheet according to Example 2 is the same as that of the wavelength conversion sheet according to Example 1. This is because the internal haze value is larger than the internal haze value, and thus the external haze value is smaller. Therefore, by including light scattering particles in the light wavelength conversion sheet to further increase the internal haze value, it is possible to further reduce the external haze value, and thus it has been confirmed that the light wavelength conversion efficiency can be further improved. .. The total haze value, internal haze value, and haze value in the light wavelength conversion sheet were measured as follows. First, using a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory), the total haze value of the light wavelength conversion sheet was measured according to JIS K7136. Then, on both sides of the light wavelength conversion sheet, a triacetyl cellulose base material (product name: “Panaclean PD-S1” manufactured by Panac) with a film thickness of 25 μm is interposed between the triacetyl cellulose base material (product name: TD60UL" manufactured by FUJIFILM Corporation) was attached. 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, a haze meter (product name “HM-150”, manufactured by Murakami Color Research Laboratory) was used to measure the haze value according to JIS K7136 to determine 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 substrate may also affect the internal haze value and the external haze value of the light wavelength conversion sheet, but if the internal scattering of the light wavelength conversion sheet is extremely large, these The effect on the internal and external haze values 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, and thus the external haze value may be 0%.

Further, in the light wavelength conversion sheets according to Examples 18 and 19, a scratch test was performed on the overcoat layer, and the vertical force and the horizontal force at that time were measured. The vertical force was 21 μN, the horizontal force was −11 μN, and the optical wavelength conversion sheet according to Example 19 had the vertical force of 11 μN and the horizontal force of −6 μN. These overcoat layers were dense films and had the ability to prevent the light wavelength conversion member from being exposed to the atmosphere. However, in the ability to prevent the light wavelength conversion member from being exposed to the air, the light wavelength conversion sheet according to Example 18 was used. It can be said that the overcoat layer is higher than the overcoat layer of the light wavelength conversion sheet according to Example 19. In the scratch test, an indenter (Cube Corner: Ti037_110410(12)) was applied 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 (Hyditron) Co., Ltd.). ) Was pushed in 50 nm and the depth was kept constant, and this indenter was moved in the horizontal direction at a moving speed of 4 μm/min for 30 seconds, and the vertical force (load) and horizontal force at that time were measured and measured. The average value of the vertical force and the horizontal force was obtained, and the average value of the five average values of the vertical force (5 times average value) obtained by repeating this scratch test 5 times was taken as the vertical force. The average value of the average values (average value of 5 times) was defined as the horizontal force.

Although CdSe is used as the core material of the green light emitting quantum dots and the red light emitting quantum dots in the above-mentioned embodiment, the same results as in the above embodiment can be obtained by using a non-Cd-based material such as InP and InAs as the core material. was gotten.

10, 20, 30, 40, 50, 60... Light wavelength conversion sheet 11, 154, 170... Light wavelength conversion member 16... Binder resin 17... Quantum dots 18... Light scattering particles 19... Coating film 70... Image display device 80 , 130, 140, 160... Backlight device 120... Display panel

Claims (14)

A light wavelength conversion composition,
Including quantum dots, and represented sulfo Sufaito compound under following general formula (2), the optical wavelength converting composition.

(In the formula, R ^4's each independently represents an optionally substituted alkyl group, an optionally substituted cycloalkyl group, an optionally substituted alkenyl group, or an optionally substituted cycloalkenyl group. represents optionally substituted alkynyl or optionally substituted aryl group or an optionally substituted aralkyl group,,, R ⁵ represents a hydrogen atom.) In the general formula (2), R ⁴ is each independently an optionally substituted alkyl group having 1 to 20 carbon atoms or an optionally substituted alkenyl group having 1 to 20 carbon atoms. The light wavelength conversion composition according to claim 1. The light wavelength conversion composition according to claim 1, wherein the compound represented by the general formula (2) has a weight average molecular weight of 150 or more and 800 or less. The light wavelength conversion composition according to claim 1, further comprising a polymerizable compound. The quantum dot includes a core made of a first semiconductor compound, a shell made of a second semiconductor compound that covers the core and is different from the first semiconductor compound, and a ligand bound to the surface of the shell. The light wavelength conversion composition according to claim 1. The light wavelength conversion composition according to claim 1, further comprising light scattering particles. A light wavelength conversion member comprising the cured product of the light wavelength conversion composition according to claim 4 . The light wavelength conversion member according to claim 7 , wherein the content of the phosphorus element in the light wavelength conversion member measured by fluorescent X-ray analysis is 0.05% by mass or more. A light wavelength conversion sheet,
A light wavelength conversion sheet comprising the light wavelength conversion member according to claim 7 , wherein the light wavelength conversion member is formed in layers. The light wavelength conversion sheet according to claim 9 , further comprising an optical member that is disposed on at least one surface side of the light wavelength conversion member and is integrated with the light wavelength conversion member. 10. The light wavelength conversion sheet according to claim 9 , wherein the light wavelength conversion sheet has a water vapor transmission rate of 0.1 g/(m ² ·24 h) or more at 40° C. and a relative humidity of 90%. The optical wavelength conversion according to claim 9 , wherein the light wavelength conversion sheet has an oxygen transmittance of 0.1 cm ³ /(m ² ·24h·atm) or more at 23°C and a relative humidity of 90%. Sheet. A light source,
And an optical wavelength conversion sheet according to the light wavelength conversion member or claim 9 according to claim 7 for receiving the light from the light source, the backlight device. The backlight device according to claim 13 ,
An image display device, comprising: a display panel disposed on a light emitting side of the backlight device.

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