WO2021084603A1

WO2021084603A1 - Resin composition for wavelength conversion, cured resin material for wavelength conversion, wavelength conversion member, backlight unit and image display device

Info

Publication number: WO2021084603A1
Application number: PCT/JP2019/042308
Authority: WO
Inventors: 和仁渡部; 友洋鮎ヶ瀬; 大介大槻; 佳希丸山
Original assignee: 昭和電工マテリアルズ株式会社
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2021-05-06

Abstract

A resin composition for wavelength conversion comprising: a multifunctional (meth)acrylate compound that has an alicyclic structure; a multifunctional thiol compound; a compound that has a carboxy group and a thiol group in a single molecule; a photopolymerization initiator; and a quantum dot fluorescent body.

Description

Wavelength conversion resin composition, wavelength conversion resin cured product, wavelength conversion member, backlight unit and image display device

The present disclosure relates to a wavelength conversion resin composition, a wavelength conversion resin cured product, a wavelength conversion member, a backlight unit, and an image display device.

In recent years, in the field of image display devices such as liquid crystal display devices, it has been required to improve the color reproducibility of displays. As a means for improving color reproducibility, a wavelength conversion member containing a quantum dot phosphor has attracted attention as described in Japanese Patent Application Laid-Open No. 2013-544018 and International Publication No. 2016/0526225.

The wavelength conversion member including the quantum dot phosphor is arranged in, for example, the backlight unit of the image display device. When a wavelength conversion member including a quantum dot phosphor that emits red light and a quantum dot phosphor that emits green light is used, when the wavelength conversion member is irradiated with blue light as excitation light, the quantum dot phosphor emits light. White light can be obtained from the red light and green light produced and the blue light transmitted through the wavelength conversion member. With the development of wavelength conversion members containing quantum dot phosphors, the color reproducibility of displays has been expanded from 72% of the conventional NTSC (National Television System Committee) ratio to 100% of the NTSC ratio.

Quantum dot phosphors are prone to deterioration due to the effects of water vapor or oxygen.
In particular, a cured product of a photocurable composition containing a quantum dot phosphor has insufficient moisture and heat resistance in a high temperature and high humidity environment, and the quantum dot phosphor tends to deteriorate and the emission intensity tends to decrease. It is in. Therefore, when an image display device using a wavelength conversion member containing a quantum dot phosphor is left in a high temperature and high humidity environment, or when the temperature of the image display device main body rises due to the use of the image display device, the quantum dots The brightness of the image display device may decrease as the phosphor deteriorates.

In order to suppress a decrease in the emission intensity of the quantum dot phosphor, at least a part of the cured product containing the quantum dot phosphor may be covered with a coating material in the wavelength conversion member containing the quantum dot phosphor. For example, in the case of a film-shaped wavelength conversion member, a barrier film having a barrier property against at least one of oxygen and water may be provided on one side or both sides of the cured product layer containing the quantum dot phosphor. However, even if a covering material such as a barrier film is provided, it may not be possible to sufficiently suppress the decrease in emission intensity.

The present disclosure has been made in view of the above circumstances, and is a wavelength conversion resin composition capable of suppressing a decrease in emission intensity of a quantum dot phosphor, and a wavelength conversion resin composition using this wavelength conversion resin composition. An object of the present invention is to provide a cured resin product, a wavelength conversion member, a backlight unit, and an image display device.

Specific means for achieving the above-mentioned problems are as follows.
<1> For wavelength conversion containing a polyfunctional (meth) acrylate compound having an alicyclic structure, a polyfunctional thiol compound, a compound having a carboxy group and a thiol group in one molecule, a photopolymerization initiator and a quantum dot phosphor. Resin composition.
<2> The resin composition for wavelength conversion according to <1>, wherein the compound having a carboxy group and a thiol group in one molecule contains two or less carboxy groups.
<3> The resin composition for wavelength conversion according to <1> or <2>, wherein the compound having a carboxy group and a thiol group in one molecule contains two or less thiol groups.
<4> The wavelength conversion according to any one of <1> to <3>, wherein at least one of the thiol groups contained in the compound having a carboxy group and a thiol group in one molecule is a primary thiol group. Resin composition.
<5> The resin composition for wavelength conversion according to any one of <1> to <4>, wherein the compound having a carboxy group and a thiol group in one molecule has a molecular weight of 80 to 300.
<6> The resin composition for wavelength conversion according to any one of <1> to <5>, wherein the compound having a carboxy group and a thiol group in one molecule is an aliphatic compound.
<7> The resin composition for wavelength conversion according to any one of <1> to <6>, which contains a monofunctional (meth) acrylate compound.
<8> The resin composition for wavelength conversion according to any one of <1> to <7>, which does not contain a liquid medium or has a liquid medium content of 0.5% by mass or less.
<9> The resin composition for wavelength conversion according to any one of <1> to <8>, which contains a white pigment.
<10> A cured resin composition for wavelength conversion, which is a cured product of the resin composition for wavelength conversion according to any one of <1> to <9>.
<11> The cured resin for wavelength conversion according to <10>, wherein the glass transition temperature measured by dynamic viscoelasticity measurement is 85 ° C. or higher.
<12> A wavelength conversion member having the cured resin for wavelength conversion according to any one of <10> and <11>.
<13> The wavelength conversion member according to <12>, which has a coating material that covers at least a part of the cured resin for wavelength conversion.
<14> The wavelength conversion member according to <12> or <13>, which is in the form of a film.
<15> The wavelength conversion member according to any one of <12> to <14> for displaying an image.
<16> A backlight unit including the wavelength conversion member according to any one of <12> to <15> and a light source.
<17> An image display device including the backlight unit according to <16>.

According to the present disclosure, a wavelength conversion resin composition capable of suppressing a decrease in emission intensity of a quantum dot phosphor, a wavelength conversion resin cured product using this wavelength conversion resin composition, a wavelength conversion member, and a bag. A light unit and an image display device can be provided.

It is a schematic cross-sectional view which shows an example of the schematic structure of the wavelength conversion member. It is a figure which shows an example of the schematic structure of the backlight unit. It is a figure which shows an example of the schematic structure of the liquid crystal display device. It is explanatory drawing of the evaluation apparatus A used in an Example. It is explanatory drawing of the evaluation apparatus B used in an Example.

Hereinafter, the mode for implementing the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps and the like) are not essential unless otherwise specified. The same applies to the numerical values and their ranges, and does not limit this disclosure.

In the present disclosure, the term "process" includes not only a process independent of other processes but also the process if the purpose of the process is achieved even if the process cannot be clearly distinguished from the other process. ..
The numerical range indicated by using "-" in the present disclosure includes the numerical values before and after "-" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
In the present disclosure, each component may contain a plurality of applicable substances. When a plurality of substances corresponding to each component are present in the composition, the content or content of each component is the total content or content of the plurality of substances present in the composition unless otherwise specified. Means quantity.
In the present disclosure, the particles corresponding to each component may include a plurality of types of particles. When a plurality of particles corresponding to each component are present in the composition, the particle size of each component means a value for a mixture of the plurality of particles present in the composition unless otherwise specified.
In the present disclosure, the term "layer" or "membrane" is used only in a part of the region in addition to the case where the layer or the membrane is formed in the entire region when the region in which the layer or the membrane is present is observed. The case where it is formed is also included.
In the present disclosure, the term "laminated" refers to stacking layers, and two or more layers may be bonded or the two or more layers may be removable.
In the present disclosure, "(meth) acryloyl group" means at least one of an acryloyl group and a methacryloyl group, "(meth) acrylate" means at least one of acrylate and methacrylate, and "(meth) allyl" means allyl. And at least one of metallicyl.

<Resin composition for wavelength conversion>
The resin composition for wavelength conversion of the present disclosure includes a polyfunctional (meth) acrylate compound having an alicyclic structure, a polyfunctional thiol compound, and a compound having a carboxy group and a thiol group in one molecule (hereinafter, "specific carboxylic acid"). It may be referred to as a "compound"), a photopolymerization initiator and a quantum dot phosphor. The wavelength conversion resin composition of the present disclosure may further contain other components, if necessary. By having the above-mentioned structure, the wavelength conversion resin composition of the present disclosure can suppress a decrease in the emission intensity of the quantum dot phosphor.

Hereinafter, the components contained in the wavelength conversion resin composition of the present disclosure will be described in detail.

(Polyfunctional (meth) acrylate compound)
The wavelength conversion resin composition of the present disclosure contains a polyfunctional (meth) acrylate compound having an alicyclic structure. The polyfunctional (meth) acrylate compound having an alicyclic structure is a polyfunctional (meth) acrylate compound having an alicyclic structure in the skeleton and having two or more (meth) acryloyl groups in one molecule. Specific examples include tricyclodecanedimethanol di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, 1,3-adamantan dimethanol di (meth) acrylate, and hydrogenated bisphenol A (poly) ethoxydi (meth) acrylate. , Hydrogenated bisphenol A (poly) propoxydi (meth) acrylate, hydrogenated bisphenol F (poly) ethoxydi (meth) acrylate, hydrogenated bisphenol F (poly) propoxydi (meth) acrylate, hydrogenated bisphenol S (poly) ethoxydi (meth) ) Acrylate type (meth) acrylate such as acrylate and hydrogenated bisphenol S (poly) propoxydi (meth) acrylate can be mentioned.
From the viewpoint of moisture and heat resistance of the wavelength conversion resin composition, it is preferable that the alicyclic structure contained in the polyfunctional (meth) acrylate compound having an alicyclic structure contains a tricyclodecane skeleton. The polyfunctional (meth) acrylate compound having a tricyclodecane skeleton in the alicyclic structure is preferably tricyclodecanedimethanol di (meth) acrylate.

The content of the polyfunctional (meth) acrylate compound having an alicyclic structure in the resin composition for wavelength conversion shall be, for example, 40% by mass to 90% by mass with respect to the total amount of the resin composition for wavelength conversion. Is more preferable, 40% by mass to 80% by mass is more preferable, and 40% by mass to 70% by mass is further preferable. When the content of the polyfunctional (meth) acrylate compound having an alicyclic structure is in the above range, the moisture and heat resistance of the cured product tends to be further improved.

The wavelength conversion resin composition may contain a polyfunctional (meth) acrylate compound having one kind of alicyclic structure alone, or a polyfunctional (meth) acrylate having two or more kinds of alicyclic structures. It may contain a combination of compounds.

(Polyfunctional thiol compound)
The wavelength conversion resin composition contains a polyfunctional thiol compound having two or more thiol groups in one molecule. When the wavelength conversion resin composition contains a polyfunctional thiol compound, an enthiol reaction proceeds between the polyfunctional (meth) acrylate compound and the polyfunctional thiol compound when the wavelength conversion resin composition is cured. The moisture and heat resistance of the cured product tends to be further improved. Further, when the wavelength conversion resin composition contains a polyfunctional thiol compound, the optical properties of the cured product tend to be further improved.

The composition containing the (meth) allyl compound and the polyfunctional thiol compound is often inferior in storage stability, although the resin composition for wavelength conversion of the present disclosure contains the polyfunctional thiol compound. Excellent storage stability. It is presumed that this is because the wavelength conversion resin composition contains a polyfunctional (meth) acrylate compound.

Specific examples of the polyfunctional thiol compound include ethylene glycol bis (3-mercaptopropionate), diethylene glycol bis (3-mercaptopropionate), tetraethylene glycol bis (3-mercaptopropionate), 1,2-. Propropylene glycol bis (3-mercaptopropionate), diethylene glycol bis (3-mercaptobutyrate), 1,4-butanediol bis (3-mercaptopropionate), 1,4-butanediol bis (3-mercaptobutyrate) Rate), 1,8-octanediol bis (3-mercaptopropionate), 1,8-octanediol bis (3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropanthris (3-mercaptopro) Pionate), trimethylolpropanetris (3-mercaptobutyrate), trimethylolpropanetris (3-mercaptoisobutyrate), trimethylolpropanetris (2-mercaptoisobutyrate), trimethylolpropanetristhioglycolate, Tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate, trimethyl ethanetris (3-mercaptobutyrate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate) ), Pentaerythritol tetrakis (3-mercaptoisobutyrate), pentaerythritol tetrakis (2-mercaptoisobutyrate), dipentaerythritol hexakis (3-mercaptopropionate), dipentaerythritol hexakis (2-mercaptopro) Pionate), dipentaerythritol hexakis (3-mercaptobutyrate), dipentaerythritol hexakis (3-mercaptoisobutyrate), dipentaerythritol hexakis (2-mercaptoisobutyrate), pentaerythritol tetrakisthioglycol Rate, dipentaerythritol hexaxthioglycolate and the like can be mentioned.

The polyfunctional thiol compound may be in the state of a thioether oligomer that has been previously reacted with the polyfunctional (meth) acrylate compound.

The thioether oligomer can be obtained by addition polymerization of a polyfunctional thiol compound and a polyfunctional (meth) acrylate compound in the presence of a polymerization initiator. When the thioether oligomer is obtained by addition polymerization, the ratio of the equivalent number of thiol groups of the polyfunctional thiol compound to the equivalent number of (meth) acryloyl groups of the polyfunctional (meth) acrylate compound as a raw material (the equivalent number of thiol groups / (meth). ) The equivalent number of acryloyl groups) is, for example, preferably 3.0 to 3.3, more preferably 3.0 to 3.2, and further preferably 3.05 to 3.15. preferable.

The weight average molecular weight of the thioether oligomer is, for example, preferably 3000 to 10000, more preferably 3000 to 8000, and even more preferably 4000 to 6000.
The weight average molecular weight of the thioether oligomer is obtained by converting the molecular weight distribution measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

The thiol equivalent of the thioether oligomer is, for example, preferably 200 g / eq to 400 g / eq, more preferably 250 g / eq to 350 g / eq, and even more preferably 250 g / eq to 270 g / eq.

The thiol equivalent of the thioether oligomer can be measured by the following iodine titration method.
0.2 g of the measurement sample is precisely weighed, and 20 mL of chloroform is added thereto to prepare a sample solution. Using 0.275 g of soluble starch dissolved in 30 g of pure water as a starch indicator, 20 mL of pure water, 10 mL of isopropyl alcohol, and 1 mL of starch indicator are added and stirred with a stirrer. The iodine solution is added dropwise, and the point at which the chloroform layer turns green is defined as the end point. At this time, the value given by the following formula is taken as the thiol equivalent of the measurement sample.
Equivalent of thiol (g / eq) = mass of measurement sample (g) x 10000 / titer of iodine solution (mL) x factor of iodine solution

(Monofunctional thiol compound)
The wavelength conversion resin composition may contain a monofunctional thiol compound having one thiol group in one molecule.

Specific examples of the monofunctional thiol compound include hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanthiol, 1-decanethiol, methyl mercaptopropionate, methoxybutyl mercaptopropionate, octyl mercaptopropionate, and mercapto. Examples thereof include tridecyl propionate, 2-ethylhexyl-3-mercaptopropionate, and n-octyl-3-mercaptopropionate.

The content of the thiol compound (total of the polyfunctional thiol compound and the monofunctional thiol compound used as needed) in the wavelength conversion resin composition is, for example, 5% by mass with respect to the total amount of the wavelength conversion resin composition. It is preferably% to 50% by mass, more preferably 5% by mass to 40% by mass, further preferably 10% by mass to 30% by mass, and further preferably 15% by mass to 30% by mass. Especially preferable. In this case, due to the enthiol reaction with the polyfunctional (meth) acrylate compound, the cured product tends to form a more dense crosslinked structure, and the moisture and heat resistance tends to be further improved.
The mass-based ratio of the polyfunctional thiol compound to the total of the polyfunctional thiol compound and the monofunctional thiol compound used as needed is preferably 60% by mass to 100% by mass, preferably 70% by mass to 100% by mass. Is more preferable, and 80% by mass to 100% by mass is further preferable.

The mass-based content ratio (total of polyfunctional (meth) acrylate compound / thiol compound) to the total of the polyfunctional (meth) acrylate compound, the polyfunctional thiol compound, and the monofunctional thiol compound used as needed is 0. It is preferably 5 to 10, more preferably 0.5 to 8.0, and even more preferably 0.5 to 6.0.

(Specific carboxylic acid compound)
The wavelength conversion resin composition contains a specific carboxylic acid compound. The specific carboxylic acid compound is not particularly limited as long as it is a compound having a carboxy group and a thiol group in one molecule.
When the thiol compound (polyfunctional thiol compound or monofunctional thiol compound) has a carboxy group, the compound is regarded as a specific carboxylic acid compound rather than a thiol compound.
The specific carboxylic acid compound may be an aromatic compound or an aliphatic compound such as a chain-type aliphatic compound or an alicyclic compound, and is preferably an aliphatic compound.
The number of carboxy groups contained in the specific carboxylic acid compound is preferably two or less, and more preferably one.
The number of thiol groups contained in the specific carboxylic acid compound is preferably two or less, and more preferably one.
At least one of the thiol groups contained in the specific carboxylic acid compound is preferably a primary thiol group, and the specific carboxylic acid compound contains one thiol group and the thiol group is a primary thiol group (that is, the specific carboxylic acid. The compound is more preferably a first thiol compound). In the present disclosure, the primary thiol group means a thiol group bonded to a primary carbon. The primary thiol compound refers to a thiol compound having a primary thiol group.
The molecular weight of the specific carboxylic acid compound is preferably 80 to 300, more preferably 90 to 250, and even more preferably 100 to 200.
Specific examples of the specific carboxylic acid compound include thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 2-mercaptobenzoic acid, 3-mercaptobenzoic acid, 4-mercaptobenzoic acid, 4-mercaptobenzoic acid, Examples thereof include 3-mercaptobutanoic acid, 2-mercaptoisobutyric acid, 3-mercaptoisobutyric acid, 2-mercaptobenzoic acid, 4-mercaptophenylacetic acid, and thioapple acid. Among these, 3-mercaptopropionic acid is preferable.

The content of the specific carboxylic acid compound in the wavelength conversion resin composition is preferably, for example, 0.5% by mass to 40% by mass, and is preferably 1% by mass to 40% by mass, based on the total amount of the wavelength conversion resin composition. It is more preferably 30% by mass, further preferably 2% by mass to 20% by mass. When the content of the specific carboxylic acid compound is 0.5% by mass or more, the brightness maintenance rate of the wavelength conversion member tends to be improved. When the content of the specific carboxylic acid compound is 40% by mass or less, the strength of the cured product of the wavelength conversion resin composition tends to be maintained.

(Photopolymerization initiator)
The wavelength conversion resin composition contains a photopolymerization initiator. The photopolymerization initiator is not particularly limited, and specific examples thereof include compounds that generate radicals when irradiated with active energy rays such as ultraviolet rays.

Specific examples of the photopolymerization initiator include benzophenone, N, N'-tetraalkyl-4,4'-diaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1, 4,4'-bis (dimethylamino) benzophenone (also referred to as "Michler ketone"), 4,4'-bis (Diethylamino) benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 1-hydroxycyclohexylphenylketone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4- (4-) Aromatic ketone compounds such as (2-hydroxyethoxy) -phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one; alkyl Kinone compounds such as anthraquinone and phenanthrenquinone; benzoin compounds such as benzoin and alkylbenzoin; benzoin ether compounds such as benzoin alkyl ether and benzoin phenyl ether; benzyl derivatives such as benzyl dimethyl ketal; 2- (o-chlorophenyl) -4,5 -Diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2,4-di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl)- 2,4,5-Triarylimidazole dimer such as 4,5-diphenylimidazole dimer; aclysine derivative such as 9-phenylaclysine, 1,7- (9,9'-acrydinyl) heptane; 1,2 -Octanedione 1- [4- (Phenylthio) -2- (O-benzoyloxime)], Ethanone 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl] -1- Oxyme ester compounds such as (O-acetyloxime); coumarin compounds such as 7-diethylamino-4-methylkumarin; thioxanthone compounds such as 2,4-diethylthioxanthone; 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4,6-trimethylbenzoyl Acylphosphine oxide compounds such as -phenyl-ethoxy-phosphine oxide; and the like. The wavelength conversion resin composition may contain one kind of photopolymerization initiator alone, or may contain two or more kinds of photopolymerization initiators in combination.

As the photopolymerization initiator, at least one selected from the group consisting of an acylphosphine oxide compound, an aromatic ketone compound, and an oxime ester compound is preferable from the viewpoint of curability, and from the acylphosphine oxide compound and the aromatic ketone compound. At least one selected from the above group is more preferable, and an acylphosphine oxide compound is further preferable.

The content of the photopolymerization initiator in the wavelength conversion resin composition is preferably, for example, 0.1% by mass to 5% by mass, and 0.1% by mass, based on the total amount of the wavelength conversion resin composition. It is more preferably% to 3% by mass, and further preferably 0.5% by mass to 1.5% by mass. When the content of the photopolymerization initiator is 0.1% by mass or more, the sensitivity of the wavelength conversion resin composition tends to be sufficient, and the content of the photopolymerization initiator is 5% by mass or less. As a result, the influence of the cured product of the wavelength conversion resin composition on the hue and the decrease in storage stability tend to be suppressed.

(Quantum dot phosphor)
The wavelength conversion resin composition contains a quantum dot phosphor. The quantum dot phosphor is not particularly limited, and examples thereof include particles containing at least one selected from the group consisting of a group II-VI compound, a group III-V compound, a group IV-VI compound, and a group IV compound. From the viewpoint of luminous efficiency, the quantum dot phosphor preferably contains a compound containing at least one of Cd and In.

Specific examples of the II-VI group compounds include CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSte, ZnSeS, ZnSeTe, ZnSte, HgSeS, ZnS. , CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSeTe
Specific examples of the Group III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, COLP, GaNAs, PLACSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb. , AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInNSb, GaInPAs, GaInPSb, InNAAl
Specific examples of the IV-VI group compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSte, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbSe ..
Specific examples of the Group IV compound include Si, Ge, SiC, SiGe and the like.

The quantum dot phosphor preferably has a core-shell structure. By making the band gap of the compound constituting the shell wider than the band gap of the compound constituting the core, it is possible to further improve the quantum efficiency of the quantum dot phosphor. Examples of the combination of core and shell (core / shell) include CdSe / ZnS, InP / ZnS, PbSe / PbS, CdSe / CdS, CdTe / CdS, and CdTe / ZnS.

Further, the quantum dot phosphor may have a so-called core multi-shell structure in which the shell has a multi-layer structure. By stacking one or more layers of shells with a narrow bandgap on a core with a wide bandgap, and further stacking a shell with a wide bandgap on top of this shell, the quantum efficiency of the quantum dot phosphor can be further improved. Is possible.

The wavelength conversion resin composition may contain one type of quantum dot phosphor alone, or may contain two or more types of quantum dot phosphors in combination. Examples of a mode in which two or more types of quantum dot phosphors are contained in combination include a mode in which two or more types of quantum dot phosphors having different components but the same average particle size are contained, and a mode in which components having different average particle sizes are contained. Examples thereof include an embodiment containing two or more types of quantum dot phosphors, and an embodiment containing two or more types of quantum dot phosphors having different components and average particle diameters. The emission center wavelength of the quantum dot phosphor can be changed by changing at least one of the components of the quantum dot phosphor and the average particle size.

For example, the wavelength conversion resin composition includes a quantum dot phosphor G having an emission center wavelength in the green wavelength range of 520 nm to 560 nm and a quantum dot phosphor R having an emission center wavelength in the red wavelength range of 600 nm to 680 nm. And may be contained. When the cured product of the wavelength conversion resin composition containing the quantum dot phosphor G and the quantum dot phosphor R is irradiated with excitation light in the blue wavelength range of 430 nm to 480 nm, the quantum dot phosphor G and the quantum dots are irradiated. Green light and red light are emitted from the phosphor R, respectively. As a result, white light can be obtained by the green light and red light emitted from the quantum dot phosphor G and the quantum dot phosphor R and the blue light transmitted through the cured product.

The quantum dot phosphor may be used in the state of a quantum dot phosphor dispersion liquid dispersed in a dispersion medium. Examples of the dispersion medium for dispersing the quantum dot phosphor include various solvents and monofunctional (meth) acrylate compounds.
Examples of the solvent that can be used as the dispersion medium include water, acetone, ethyl acetate, toluene, n-hexane and the like.
The monofunctional (meth) acrylate compound that can be used as a dispersion medium is not particularly limited as long as it is a liquid at room temperature (25 ° C.), and isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and the like are used. Can be mentioned.
Among these, the dispersion medium is preferably a monofunctional (meth) acrylate compound from the viewpoint of eliminating the step of volatilizing the dispersion medium when curing the wavelength conversion resin composition, and has an alicyclic structure. It is more preferably a monofunctional (meth) acrylate compound having, more preferably isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate, and particularly preferably isobornyl (meth) acrylate.

When a monofunctional (meth) acrylate compound is used as the dispersion medium, the content ratio based on the mass of the monofunctional (meth) acrylate compound and the polyfunctional (meth) acrylate compound (monofunctional (meth) acrylate compound / polyfunctional (meth)). The acrylate compound) is preferably 0.01 to 0.30, more preferably 0.02 to 0.20, and even more preferably 0.05 to 0.20.

The mass-based ratio of the quantum dot phosphor to the quantum dot phosphor dispersion liquid is preferably 1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass.

The content of the quantum dot phosphor dispersion liquid in the wavelength conversion resin composition is wavelength conversion when the mass-based ratio of the quantum dot phosphor to the quantum dot phosphor dispersion liquid is 1% by mass to 20% by mass. For example, it is preferably 1% by mass to 10% by mass, more preferably 4% by mass to 10% by mass, and 4% by mass to 7% by mass with respect to the total amount of the resin composition for use. More preferred.
The content of the quantum dot phosphor in the wavelength conversion resin composition is preferably, for example, 0.01% by mass to 1.0% by mass, based on the total amount of the wavelength conversion resin composition. It is more preferably 0.05% by mass to 0.5% by mass, and further preferably 0.1% by mass to 0.5% by mass. When the content of the quantum dot phosphor is 0.01% by mass or more, sufficient emission intensity tends to be obtained when the cured product is irradiated with excitation light, and the content of the quantum dot phosphor is 1.0. When it is mass% or less, the aggregation of the quantum dot phosphor tends to be suppressed.

(Liquid medium)
The wavelength conversion resin composition preferably does not contain a liquid medium or has a liquid medium content of 0.5% by mass or less. The liquid medium means a medium in a liquid state at room temperature (25 ° C.).

Specific examples of the liquid medium include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl isopropyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, diethyl ketone, and the like. Ketone solvents such as dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentandione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl-n-propyl ether, diisopropyl Ether, tetrahydrofuran, methyl tetrahydrofuran, dioxane, dimethyl dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, Diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tri Ethylene glycol methyl ethyl ether, triethylene glycol methyl-n-butyl ether, triethylene glycol di-n-butyl ether, triethylene glycol methyl-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ethyl Ether, tetraethylene glycol methyl-n-butyl ether, tetraethylene glycol di-n-butyl ether, tetraethylene glycol methyl-n-hexyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol Di-n-butyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol methyl-n-butyl ether, dipropi Lenglycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl ethyl ether, tripropylene glycol methyl -N-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl ethyl ether, tetrapropylene glycol methyl-n-butyl ether , Tetrapropylene glycol di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether and other ether solvents; propylene carbonate, ethylene carbonate, diethyl carbonate and other carbonate solvents; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate , N-butyl acetate, isobutyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2- (2-) Butoxyethoxy) ethyl, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl acetate ether , Glycol diacetate, methoxytriethylene glycol acetate, ethyl propionate, n-butyl propionate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n lactate -Amil, ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, γ -Ester solvents such as butyrolactone and γ-valerolactone; acetonitrile, N- Aprotonic polarities such as methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, etc. Solvents: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol, t-pentanol , 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol , Se-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, Alcohol solvents such as diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether. , Diethylene glycol mono-n-hexyl ether, triethylene glycol monoethyl ether, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, etc. Glycol monoether solvent; terpene solvent such as terpinene, terpineol, milsen, aloosimene, limonene, dipentene, pinene, carboxylic, ossimen, ferlandrene; straight silicone oil such as dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil; Amino-modified silicone oil, epoxy-modified silicone oil, cal Boxy-modified silicone oil, carbinol-modified silicone oil, mercapto-modified silicone oil, heterologous functional group-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, hydrophilic special-modified silicone oil, higher alkoxy-modified silicone oil, higher fatty acid Modified silicone oils such as modified silicone oils and fluorine-modified silicone oils; butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, Saturated aliphatic monocarboxylic acids having 4 or more carbon atoms such as hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, icosanoic acid, and eicosenoic acid; Saturated aliphatic monocarboxylic acids; and the like. When the wavelength conversion resin composition contains a liquid medium, one type of liquid medium may be contained alone, or two or more types of liquid media may be contained in combination.

(White pigment)
The wavelength conversion resin composition may further contain a white pigment.
Specific examples of the white pigment include titanium oxide, barium sulfate, zinc oxide, calcium carbonate and the like. Among these, titanium oxide is preferable from the viewpoint of light scattering efficiency.
When the wavelength conversion resin composition contains titanium oxide as a white pigment, the titanium oxide may be rutile-type titanium oxide or anatase-type titanium oxide, and is preferably rutile-type titanium oxide.

The average particle size of the white pigment is preferably 0.1 μm to 1 μm, more preferably 0.2 μm to 0.8 μm, and even more preferably 0.2 μm to 0.5 μm.
In the present disclosure, the average particle size of the white pigment can be measured as follows.
The white pigment extracted from the wavelength conversion resin composition is dispersed in purified water containing a surfactant to obtain a dispersion liquid. In the volume-based particle size distribution measured by a laser diffraction type particle size distribution measuring device (for example, Shimadzu Corporation, SALD-3000J) using this dispersion, the value when the integration from the small diameter side is 50% ( The median diameter (D50)) is defined as the average particle size of the white pigment. Examples of the method of extracting the white pigment from the wavelength conversion resin composition include a method of diluting the wavelength conversion resin composition with a liquid medium and precipitating the white pigment by centrifugation or the like to distribute the white pigment.
The average particle size of the white pigment contained in the cured resin for wavelength conversion is the equivalent circle diameter (geometric mean of major axis and minor axis) for 50 particles by observing the particles using a scanning electron microscope. It can be calculated and calculated as the arithmetic mean value.

When the wavelength conversion resin composition contains a white pigment, the white particles have an organic substance layer containing an organic substance on at least a part of the surface from the viewpoint of suppressing aggregation of the white pigment in the wavelength conversion resin composition. It is preferable to have. The organic substances contained in the organic substance layer include organic silane, organosiloxane, fluorosilane, organic phosphonate, organic phosphoric acid compound, organic phosphinate, organic sulfonic acid compound, carboxylic acid, carboxylic acid ester, carboxylic acid derivative, amide, and hydrocarbon. Examples thereof include waxes, polyolefins, copolymers of polyolefins, polyols, derivatives of polyols, alkanolamines, derivatives of alkanolamines, organic dispersants and the like.
The organic substance contained in the organic substance layer preferably contains a polyol, an organic silane, or the like, and more preferably contains at least one of the polyol or the organic silane.
Specific examples of organic silanes include octyltriethoxysilane, nonyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, tridecyltriethoxysilane, tetradecyltriethoxysilane, pentadecyltriethoxysilane, and hexadecyltriethoxysilane. Examples thereof include silane, heptadecyltriethoxysilane, and octadecyltriethoxysilane.
Specific examples of the organosiloxane include polydimethylsiloxane (PDMS) terminated with a trimethylsilyl functional group, polymethylhydrosiloxane (PMHS), polysiloxane induced by functionalization of PMHS with an olefin (by hydrosilylation), and the like. Be done.
Specific examples of organic phosphonates include n-octylphosphonic acid and its ester, n-decylphosphonic acid and its ester, 2-ethylhexylphosphonic acid and its ester, and camphyl phosphonic acid and its ester.
Specific examples of the organic phosphoric acid compound include organic acidic phosphate, organic pyrophosphate, organic polyphosphate, organic metaphosphate, salts thereof and the like.
Specific examples of the organic phosphinate include n-hexylphosphinic acid and its ester, n-octylphosphinic acid and its ester, di-n-hexylphosphinic acid and its ester, and di-n-octylphosphinic acid and its ester. Can be mentioned.
Specific examples of the organic sulfonic acid compound include alkyl sulfonic acids such as hexyl sulfonic acid, octyl sulfonic acid, and 2-ethylhexyl sulfonic acid, these alkyl sulfonic acids, metal ions such as sodium, calcium, magnesium, aluminum, and titanium, and ammonium. Examples thereof include salts with ions and organic ammonium ions such as triethanolamine.
Specific examples of the carboxylic acid include maleic acid, malonic acid, fumaric acid, benzoic acid, phthalic acid, stearic acid, oleic acid, linoleic acid and the like.
Specific examples of the carboxylic acid ester include the above carboxylic acid, ethylene glycol, propylene glycol, trimethylolpropane, diethanolamine, triethanolamine, glycerol, hexanetriol, erythritol, mannitol, sorbitol, pentaerythritol, bisphenol A, hydroquinone, and flo. Examples thereof include esters and partial esters produced by reaction with a hydroxy compound such as loglucinol.
Specific examples of the amide include stearic acid amide, oleic acid amide, and erucic acid amide.
Specific examples of the polyolefin and its copolymer include a copolymer of polyethylene, polypropylene, ethylene and one or more compounds selected from propylene, butylene, vinyl acetate, acrylate, acrylamide and the like.
Specific examples of the polyol include glycerol, trimethylolethane, trimethylolpropane and the like.
Specific examples of the alkanolamine include diethanolamine and triethanolamine.
Specific examples of the organic dispersant include high molecular weight organic dispersants having functional groups such as citric acid, polyacrylic acid, polymethacrylic acid, anionic, cationic, bipolar and nonionic.
When the aggregation of the white pigment in the wavelength conversion resin composition is suppressed, the dispersibility of the white pigment in the wavelength conversion resin cured product tends to be improved.

The white pigment may have an oxide layer containing a metal oxide or the like on at least a part of the surface thereof. Examples of the metal oxide contained in the oxide layer include silicon dioxide, aluminum oxide, zirconia, phosphoria, and boria. The oxide layer may be one layer or two or more layers. When the white pigment has two oxide layers, it preferably contains a first oxide layer containing silicon dioxide and a second oxide layer containing aluminum oxide.
When the white pigment has an oxide layer, the dispersibility of the white pigment in the cured resin for wavelength conversion including the alicyclic structure and the sulfide structure tends to be improved.

The white pigment may have an organic substance layer and an oxide layer. In this case, it is preferable that the oxide layer and the organic substance layer are provided on the surface of the white pigment in the order of the oxide layer and the organic substance layer. When the white pigment has an organic material layer and two oxide layers, the first oxide layer containing silicon dioxide, the second oxide layer containing aluminum oxide and the organic material layer are placed on the surface of the white pigment. It is preferable that the monooxide layer, the second oxide layer, and the organic substance layer are provided in this order.

When the wavelength conversion resin composition contains a white pigment, the content of the white pigment in the wavelength conversion resin composition is, for example, 0.1% by mass to 5% by mass with respect to the total amount of the wavelength conversion resin composition. It is preferably mass%, more preferably 0.5% by mass to 4% by mass, and even more preferably 1% by mass to 3% by mass.

(Other ingredients)
The wavelength conversion resin composition may further contain other components such as a polymerization inhibitor, a silane coupling agent, a surfactant, an adhesion imparting agent, and an antioxidant. The wavelength conversion resin composition may contain one type alone or a combination of two or more types for each of the other components.
Further, the wavelength conversion resin composition may contain a (meth) allyl compound, if necessary.

(Method for preparing resin composition for wavelength conversion)
The wavelength conversion resin composition contains a polyfunctional (meth) acrylate compound having an alicyclic structure, a polyfunctional thiol compound, a specific carboxylic acid compound, a photopolymerization initiator and a quantum dot phosphor, and other components as necessary. It can be prepared by mixing by a conventional method. The quantum dot phosphors are preferably mixed in a state of being dispersed in a liquid medium.

(Use of resin composition for wavelength conversion)
The wavelength conversion resin composition can be suitably used for film formation. Further, the wavelength conversion resin composition can be suitably used for forming a wavelength conversion member.

<Cured resin for wavelength conversion>
The wavelength conversion resin cured product of the present disclosure is a cured product of the wavelength conversion resin composition of the present disclosure. Since the wavelength conversion resin composition of the present disclosure contains a polyfunctional (meth) acrylate compound having an alicyclic structure, a polyfunctional thiol compound, etc., the cured resin composition for wavelength change of the present disclosure has an alicyclic structure. Includes sulfide structures. It is presumed that the cured resin for wavelength conversion of the present disclosure including an alicyclic structure and a sulfide structure is excellent in moisture and heat resistance.

The alicyclic structure contained in the cured resin for wavelength change is not particularly limited. Specific examples of the alicyclic structure include a tricyclodecane skeleton, a cyclohexane skeleton, a 1,3-adamantane skeleton, a hydrogenated bisphenol A skeleton, a hydrogenated bisphenol F skeleton, a hydrogenated bisphenol S skeleton, and an isobornyl skeleton. Among these, a tricyclodecane skeleton or an isobornyl skeleton is preferable, and a tricyclodecane skeleton is more preferable.

The alicyclic structure contained in the cured resin for wavelength change may be one type alone or at least two types, and preferably at least two types.
When at least two types of alicyclic structures are contained in the cured resin for wavelength change, the alicyclic structure combinations include a combination of a tricyclodecane skeleton and an isobornyl skeleton, a combination of a hydrogenated bisphenol A skeleton and an isobornyl skeleton, and the like. Can be mentioned. Among these, a combination of a tricyclodecane skeleton and an isobornyl skeleton is preferable.

The peak area (V1) attributable to SH expansion and contraction vibration and the peak area (V2) attributable to CH expansion and contraction vibration in the cured resin for wavelength change measured by a Fourier transform infrared spectrophotometer. The ratio (V1 / V2) is preferably 0.005 or less, more preferably 0.004 or less, and even more preferably 0.002 or less.
The small ratio (V1 / V2) in the cured resin for wavelength change suggests that there are few thiol groups that do not contribute to the polymerization reaction. If the number of thiol groups that do not contribute to the polymerization reaction is small, the glass transition temperature of the cured resin for wavelength change tends to increase.
The peak area (V1) attributable to SH expansion and contraction vibration and the peak area (V2) attributable to CH expansion and contraction vibration in the cured resin for wavelength change are as follows using a Fourier transform infrared spectrophotometer. The value measured by the method.
Using an FT-IR Spectrometer (Perkin Elmer), the surface of the cured resin for wavelength change to be measured is analyzed by ATR (Attenuated Total Reflection). The background measurement is performed with air, and the FT-IR measurement is performed under the condition that the number of integrations is 16 times.

The cured resin for wavelength change may include a white pigment. Details of the white pigment included in the cured resin composition for wavelength change are as described in the section of the resin composition for wavelength conversion described above.

From the viewpoint of further improving the adhesion to the coating material, the cured resin for wavelength change has a loss tangent (tan δ) of 0.4 to 1 measured under the conditions of a frequency of 10 Hz and a temperature of 25 ° C. by dynamic viscoelasticity measurement. It is preferably 5, more preferably 0.4 to 1.2, and even more preferably 0.4 to 0.6. The loss tangent (tan δ) of the cured resin for wavelength change can be measured using a dynamic viscoelasticity measuring device (for example, Rheometric Scientific, Solid Analyzer RSA-III).

Further, the cured resin for wavelength change preferably has a glass transition temperature (Tg) of 85 ° C. or higher, preferably 85 ° C. to 160 ° C., from the viewpoint of further improving the adhesion to the coating material, heat resistance, and moist heat resistance. The temperature is more preferably 90 ° C to 120 ° C. The glass transition temperature (Tg) of the cured resin for wavelength change can be measured under the condition of a frequency of 10 Hz using a dynamic viscoelasticity measuring device (for example, Rheometric Scientific, Solid Analyzer RSA-III).

^{Further, the cured resin for wavelength change has a storage elastic modulus of 1 × 10 7} Pa measured under the conditions of a frequency of 10 Hz and a temperature of 25 ° C. from the viewpoint of further improving the adhesion to the coating material, heat resistance, and moist heat resistance. ~ is preferably 1 × ^{10 10} Pa, 5 × more preferably ^{^{10 7 Pa ~ 1 × 10 10}} Pa, further preferably ^{5 × 10 7 Pa ~ 5 ×} 10 9 Pa. The storage elastic modulus of the cured resin for wavelength change can be measured using a dynamic viscoelasticity measuring device (for example, Rheometric Scientific, Solid Analyzer RSA-III).

The curing conditions of the wavelength conversion resin composition for obtaining the wavelength change resin cured product will be described later.

<Wavelength conversion member>
The wavelength conversion member of the present disclosure has a cured resin for wavelength conversion of the present disclosure. The wavelength conversion member of the present disclosure may include other components such as a covering material described later, if necessary.
The wavelength conversion member of the present disclosure is suitably used for displaying an image.

The shape of the wavelength conversion member is not particularly limited, and examples thereof include a film shape and a lens shape. When the wavelength conversion member is applied to a backlight unit described later, the wavelength conversion member is preferably in the form of a film.

When the wavelength conversion member is in the form of a film, the average thickness of the wavelength conversion member is, for example, preferably 50 μm to 200 μm, more preferably 50 μm to 150 μm, and even more preferably 80 μm to 120 μm. When the average thickness of the wavelength conversion member is 50 μm or more, the wavelength conversion efficiency tends to be further improved, and when the average thickness is 200 μm or less, the backlight is applied to the backlight unit described later. There is a tendency for the unit to be thinner.
The average thickness of the film-shaped wavelength conversion member is obtained as, for example, an arithmetic mean value of the thicknesses of any three points measured using a micrometer.
In the present disclosure, the average thickness of the film-shaped wavelength conversion member means the average thickness of the film-shaped wavelength conversion member itself when the wavelength conversion member does not have a coating material, and when the wavelength conversion member has a coating material. Refers to the average thickness of the wavelength conversion member (that is, the cured product layer) excluding the coating material.

The wavelength conversion member may be one obtained by curing one kind of wavelength conversion resin composition, or may be one obtained by curing two or more kinds of wavelength conversion resin compositions. For example, when the wavelength conversion member is in the form of a film, the wavelength conversion member includes a layer of a first wavelength conversion resin cured product obtained by curing a wavelength conversion resin composition containing a first quantum dot phosphor and a first layer of the wavelength conversion resin cured product. A layer of a cured resin composition for wavelength conversion obtained by curing a resin composition for wavelength conversion containing a second quantum dot phosphor having different emission characteristics from the quantum dot phosphor of 1 is laminated. You may.

The wavelength conversion member can be obtained by forming a coating film, a molded product, or the like of a wavelength conversion resin composition, performing a drying treatment as necessary, and then irradiating with active energy rays such as ultraviolet rays. The wavelength and irradiation amount of the active energy rays can be appropriately set according to the composition of the wavelength conversion resin composition. In one aspect, it is irradiated with ultraviolet rays having a wavelength of 280 nm ~ 400 nm at an irradiation amount of ^{100mJ / cm 2 ~ 5000mJ / cm} 2. Examples of the ultraviolet source include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and the like.

The wavelength conversion member of the present disclosure may have a coating material that covers at least a part of the cured resin for wavelength conversion. For example, when the cured resin for wavelength conversion is in the form of a film, one or both sides of the cured resin for wavelength conversion in the form of a film may be coated with a film-like covering material.

The coating material preferably has a barrier property against at least one of oxygen and water, and more preferably has a barrier property against both oxygen and water, from the viewpoint of further suppressing a decrease in the emission intensity of the quantum dot phosphor. The coating material having a barrier property against at least one of oxygen and water is not particularly limited, and known coating materials such as a barrier film having an inorganic layer and a barrier film having an organic substance layer can be used.
Conventionally, when a barrier film having an inorganic layer is used as a coating material, the quantum dot phosphor near the pinhole existing in the inorganic layer may be deactivated and black spots may be generated on the wavelength conversion member. However, since the wavelength conversion member has the cured resin for wavelength change of the present disclosure, there is a tendency that the occurrence of black spot defects can be suppressed.

When the covering material is in the form of a film, the average thickness of the covering material is, for example, preferably 10 μm to 150 μm, more preferably 30 μm to 140 μm, and even more preferably 50 μm to 135 μm. When the average thickness is 10 μm or more, the functions such as barrier property tend to be sufficient, and when the average thickness is 150 μm or less, the decrease in light transmittance tends to be suppressed.
The average thickness of the film-shaped covering material is obtained in the same manner as in the film-shaped wavelength conversion member.

Oxygen permeability of the dressing, for example, is preferably ^{0.5mL / (m 2 · 24h ·} atm) or less, more preferably ^{0.3mL / (m 2 · 24h ·} atm) or less, 0 and more preferably ^{.1mL / (m 2 · 24h ·} atm) or less. The oxygen permeability of the coating material can be measured using an oxygen permeability measuring device (for example, MOCON, OX-TRAN) under the conditions of a temperature of 23 ° C. and a relative humidity of 65%.
Further, the water vapor permeability of the dressing, for example, 5 × ¹⁰ -2 ^g / is preferably (m 2 · 24h · Pa) or ^{^{less, 1 × 10 -2 g / (}} m 2 · 24h · Pa) or less more preferably, even more preferably ^{^{5 × 10 -3 g / (m}} 2 · 24h · Pa) or less. The water vapor permeability of the coating material can be measured using a water vapor permeability measuring device (for example, MOCON, AQUATRAN) under the conditions of a temperature of 40 ° C. and a relative humidity of 90%.

From the viewpoint of further improving the light utilization efficiency, the wavelength conversion member of the present disclosure preferably has a total light transmittance of 55% or more, more preferably 60% or more, and more preferably 65% or more. More preferred. The total light transmittance of the wavelength conversion member can be measured according to the measurement method of JIS K 7361-1: 1997.

Further, the wavelength conversion member of the present disclosure preferably has a haze of 95% or more, more preferably 97% or more, and further preferably 99% or more, from the viewpoint of further improving the light utilization efficiency. preferable. The haze of the wavelength conversion member can be measured according to the measurement method of JIS K 7136: 2000.

FIG. 1 shows an example of the schematic configuration of the wavelength conversion member. However, the wavelength conversion member of the present disclosure is not limited to the configuration shown in FIG. Further, the sizes of the layer of the cured resin for wavelength conversion and the coating material in FIG. 1 are conceptual, and the relative relationship between the sizes is not limited to this. In each drawing, the same member may be designated by the same reference numeral, and duplicate description may be omitted.

The wavelength conversion member 10 shown in FIG. 1 has a cured product layer 11 which is a film-shaped cured resin for wavelength conversion, and film-shaped

coating materials

12A and 12B provided on both sides of the cured product layer 11. The types and average thicknesses of the covering material 12A and the covering material 12B may be the same or different.

The wavelength conversion member having the configuration shown in FIG. 1 can be manufactured by, for example, the following known manufacturing method.

First, a wavelength conversion resin composition is applied to the surface of a film-like coating material (hereinafter, also referred to as "first coating material") that is continuously conveyed to form a coating film. The method for applying the wavelength conversion resin composition is not particularly limited, and examples thereof include a die coating method, a curtain coating method, an extrusion coating method, a rod coating method, and a roll coating method.

Next, a film-like coating material (hereinafter, also referred to as "second coating material") that is continuously conveyed is attached onto the coating film of the wavelength conversion resin composition.

Next, the coating film is cured and a cured product layer is formed by irradiating the active energy rays from the side of the first coating material and the second coating material that can transmit the active energy rays. Then, by cutting out to a specified size, a wavelength conversion member having the configuration shown in FIG. 1 can be obtained.

If neither the first coating material nor the second coating material can transmit the active energy rays, the coating film is irradiated with the active energy rays before the second coating material is bonded, and the cured product layer is formed. May be formed.

<Backlight unit>
The backlight unit of the present disclosure includes the wavelength conversion member of the present disclosure described above and a light source.

The backlight unit is preferably a multi-wavelength light source from the viewpoint of improving color reproducibility. In a preferred embodiment, blue light having an emission center wavelength in the wavelength range of 430 nm to 480 nm and having an emission intensity peak having a half-value width (half-value full width) of 100 nm or less, and an emission center wavelength in the wavelength range of 520 nm to 560 nm. Green light having an emission intensity peak having a half-value width of 100 nm or less, and red light having an emission center wavelength in the wavelength range of 600 nm to 680 nm and having an emission intensity peak having a half-value width of 100 nm or less. A backlight unit that emits light can be mentioned. The half-value width of the emission intensity peak means the peak width at a height of 1/2 of the peak height.

From the viewpoint of further improving the color reproducibility, the emission center wavelength of the blue light emitted by the backlight unit is preferably in the range of 440 nm to 475 nm. From the same viewpoint, the emission center wavelength of the green light emitted by the backlight unit is preferably in the range of 520 nm to 545 nm. From the same viewpoint, the emission center wavelength of the red light emitted by the backlight unit is preferably in the range of 610 nm to 640 nm.

Further, from the viewpoint of further improving the color reproducibility, the half-value width of each emission intensity peak of the blue light, green light, and red light emitted by the backlight unit is preferably 80 nm or less, preferably 50 nm or less. It is more preferably 40 nm or less, particularly preferably 30 nm or less, and extremely preferably 25 nm or less.

As the light source of the backlight unit, for example, a light source that emits blue light having a emission center wavelength in the wavelength range of 430 nm to 480 nm can be used. Examples of the light source include an LED (Light Emitting Diode) and a laser. When a light source that emits blue light is used, the wavelength conversion member preferably includes at least a quantum dot phosphor R that emits red light and a quantum dot phosphor G that emits green light. As a result, white light can be obtained from the red light and green light emitted from the wavelength conversion member and the blue light transmitted through the wavelength conversion member.

Further, as the light source of the backlight unit, for example, a light source that emits ultraviolet light having a emission center wavelength in the wavelength range of 300 nm to 430 nm can be used. Examples of the light source include LEDs and lasers. When a light source that emits ultraviolet light is used, the wavelength conversion member preferably includes a quantum dot phosphor B that is excited by excitation light and emits blue light, together with a quantum dot phosphor R and a quantum dot phosphor G. As a result, white light can be obtained from the red light, green light, and blue light emitted from the wavelength conversion member.

The backlight unit of the present disclosure may be an edge light type or a direct type.

Fig. 2 shows an example of the schematic configuration of the edge light type backlight unit. However, the backlight unit of the present disclosure is not limited to the configuration shown in FIG. Further, the size of the members in FIG. 2 is conceptual, and the relative relationship between the sizes of the members is not limited to this.

The backlight unit 20 shown in FIG. 2 includes a light source 21 for emitting the blue light L _B, a light guide plate 22 to be emitted guiding the blue light L _B emitted from the light source 21, the light guide plate 22 and disposed to face The wavelength conversion member 10 is provided with a retroreflective member 23 arranged to face the light source plate 22 via the wavelength conversion member 10, and a reflector 24 arranged to face the wavelength conversion member 10 via the light guide plate 22. .. Wavelength conversion member 10 emits the red light L _R and the green light L _G part of the blue light L _B as the excitation light, the red light L and _R and the green light L _G, the blue light was not the excitation light L Exit _B. The red light _{L R,} the green light _{L G,} and the blue light _{L B,} the white light _{L W} is emitted from the retroreflective member 23.

<Image display device>
The image display device of the present disclosure includes the backlight unit of the present disclosure described above. The image display device is not particularly limited, and examples thereof include a liquid crystal display device.

FIG. 3 shows an example of the schematic configuration of the liquid crystal display device. However, the liquid crystal display device of the present disclosure is not limited to the configuration shown in FIG. Further, the size of the members in FIG. 3 is conceptual, and the relative relationship between the sizes of the members is not limited to this.

The liquid crystal display device 30 shown in FIG. 3 includes a backlight unit 20 and a liquid crystal cell unit 31 arranged to face the backlight unit 20. The liquid crystal cell unit 31 has a configuration in which the liquid crystal cell 32 is arranged between the polarizing plate 33A and the polarizing plate 33B.

The drive method of the liquid crystal cell 32 is not particularly limited, and is a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, a VA (Vertical Birefringence) method, an IPS (In-Plane-Switching) method, and an OCB (Optical Reference) method. The method and the like can be mentioned.

Hereinafter, the present disclosure will be specifically described with reference to Examples, but the present disclosure is not limited to these Examples.

<Examples 1A to 6A and Comparative Examples 1A and 2A>
(Preparation of resin composition for wavelength conversion)
The wavelength conversion resin compositions of Examples 1A to 6A and Comparative Examples 1A and 2A were prepared by mixing each component shown in Table 1 in the blending amount (unit: parts by mass) shown in the same table. "-" In Table 1 means unblended.
The meanings of the abbreviations in the table are as follows.
PETMP: Pentaerythritol tetrakis (3-mercaptopropionate) (SC Organic Chemistry Co., Ltd., PEMP)
TCDD: Tricyclodecanedimethanol diacrylate (Shin Nakamura Chemical Industry Co., Ltd., A-DCP)
Titanium oxide: The Chemours Company, Typure R-706, particle size 0.36 μm was used. On the surface of titanium oxide, a first oxide layer containing silicon oxide, a second oxide layer containing aluminum oxide, and an organic material layer containing a polyol compound are provided in this order in the order of the first oxide layer, the second oxide layer, and the organic material layer. Has been done.
Hyt: 4-Hydroxy-2,2,6,6-Tetramethylpiperidin-N-oxyl (ADEKA Corporation, ADEKA STAB LA-7RD)
TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (BASF, IRGACURE TPO)
Green Gen3.5: CdSe / ZnS (core / shell) dispersion (Nanosys, Gen3.5 QD Concentrate) was used. Isobornyl acrylate was used as a dispersion medium for this CdSe / ZnS (core / shell) dispersion liquid. The CdSe / ZnS (core / shell) dispersion contains 90% by mass or more of isobornyl acrylate.
Red Gen2.8: CdSe / ZnS (core / shell) dispersion (Nanosys, Gen2.8 QD Concentrate) was used. Isobornyl acrylate was used as a dispersion medium for this CdSe / ZnS (core / shell) dispersion liquid. The CdSe / ZnS (core / shell) dispersion contains 90% by mass or more of isobornyl acrylate.

(Manufacturing of wavelength conversion member)
Each wavelength conversion resin composition obtained above was applied onto a PET film (TA063, Toyobo Co., Ltd.) (coating material) having an average thickness of 100 μm to form a coating film. A PET film (TA063, Toyo Boseki Co., Ltd.) (coating material) with a thickness of 100 μm is laminated on this coating film, and ultraviolet rays are irradiated using an ultraviolet irradiation device (Igraphics Co., Ltd.) (irradiation amount: 1000 mJ / cm ² ). By doing so, wavelength conversion members in which coating materials were arranged on both sides of the cured product layer containing the cured resin for wavelength conversion were obtained. The average thickness of the cured product layer was 100 μm.

<Evaluation>
Each of the following evaluation items was evaluated using the wavelength conversion members obtained in Examples 1A to 6A and Comparative Examples 1A and 2A. The results are shown in Table 1.

(Brightness maintenance rate)
Each wavelength conversion member obtained above was cut into a size of 17 mm in diameter, and an evaluation sample was prepared. The brightness of the evaluation sample was measured with a fiber multi-channel spectrometer (Ocean Photonics Co., Ltd., Ocean View). The evaluation sample was processed under the conditions of the following conditions 1A to 4A, the brightness of the evaluation sample before and after the processing was obtained, and the brightness maintenance rate of the wavelength conversion member was calculated according to the following formula.
Luminance maintenance rate: (RLb / RLa) x 100
RLa: Initial brightness RLb: Brightness after processing under any of the conditions 1A to 4A (condition)
Condition 1A: The wavelength conversion member was allowed to stand for 100 hours in a constant temperature and humidity chamber set under the conditions of 85 ° C. and 5% RH. During the standing, the wavelength conversion member was continuously irradiated with light from a 150 mW light source (Light BOX (Nanosys) (LED peak wavelength 448 nm)).
Condition 2A: The wavelength conversion member was allowed to stand for 100 hours in a constant temperature and humidity chamber set under the conditions of 65 ° C. and 95% RH. During the standing, the wavelength conversion member was continuously irradiated with light from a 60 mW light source (Light BOX (Nanosys) (LED peak wavelength 448 nm)).
Condition 3A: The wavelength conversion member was allowed to stand for 100 hours in a constant temperature and humidity chamber set under the conditions of 65 ° C. and 95% RH.
Condition 4A: The wavelength conversion member was allowed to stand for 100 hours in a constant temperature and humidity chamber set under the conditions of 25 ° C. and 50% RH.

<Examples 1B to 6B and Comparative Examples 1B and 2B>
(Manufacturing of wavelength conversion member)
The wavelength conversion resin compositions of Examples 1B to 6B and Comparative Examples 1B and 2B were the same as the wavelength conversion resin compositions of Examples 1A to 6A and Comparative Examples 1A and 2A, respectively.
In Examples 1B to 6B and Comparative Examples 1B and 2B, a barrier film having an inorganic layer (a barrier film having an average thickness of 125 μm (Dainippon Printing Co., Ltd.)) was used instead of the PET film.
Each wavelength conversion resin composition was applied onto a barrier film (barrier film having an average thickness of 125 μm (Dainippon Printing Co., Ltd.)) (coating material) to form a coating film. A barrier film (barrier film with an average thickness of 125 μm (Dainippon Printing Co., Ltd.)) (coating material) is attached to this coating film, and ultraviolet rays are irradiated using an ultraviolet irradiation device (Igraphics Co., Ltd.) (irradiation amount: By 1000 mJ / cm ² ), wavelength conversion members in which coating materials were arranged on both sides of a cured product layer containing a cured resin for wavelength conversion were obtained. The average thickness of the cured product layer was 100 μm.

<Evaluation>
Each of the following evaluation items was evaluated using the wavelength conversion members obtained in Examples 1B to 6B and Comparative Examples 1B and 2B. The results are shown in Table 2.

(Brightness maintenance rate)
The brightness maintenance rate was evaluated in the same manner as in Example 1A and the like. The results obtained are shown in Table 2. The processing conditions were changed to the following conditions 1B to 4B instead of the conditions 1A to 4A.
(conditions)
Condition 1B: The wavelength conversion member was allowed to stand for 500 hours in a constant temperature and humidity chamber set under the conditions of 85 ° C. and 5% RH. During the standing, the wavelength conversion member was continuously irradiated with light from a 150 mW light source (Light BOX (Nanosys) (LED peak wavelength 448 nm)).
Condition 2B: The wavelength conversion member was allowed to stand for 500 hours in a constant temperature and humidity chamber set under the conditions of 65 ° C. and 95% RH. During the standing, the wavelength conversion member was continuously irradiated with light from a 60 mW light source (Light BOX (Nanosys) (LED peak wavelength 448 nm)).
Condition 3B: The wavelength conversion member was allowed to stand for 500 hours in a constant temperature and humidity chamber set under the conditions of 65 ° C. and 95% RH.
Condition 4B: The wavelength conversion member was allowed to stand for 500 hours in a constant temperature and humidity chamber set under the conditions of 25 ° C. and 50% RH.

(Poor black spot)
The evaluation wavelength conversion member cut into a size of 17 mm in diameter was treated under the following condition 5B. With respect to the processed wavelength conversion member for evaluation, the presence or absence of black spot defects was visually evaluated using the evaluation device A shown in FIG. 4 and the evaluation device B shown in FIG. Black spot defects are more likely to be observed in the evaluation device A than in the evaluation device B.
The evaluation device A shown in FIG. 4 has a blue LED light source 40 and a diffuser plate 42 arranged on the blue LED light source 40. The blue LED light source 40 has a plurality of blue LEDs 44, a drive substrate 46 for driving the blue LEDs 44, and a reflective sheet 48 arranged around the blue LEDs 44 on the surface of the drive substrate 46. An aluminum plate 50 is arranged on the side opposite to the side that emits blue light of the plurality of blue LEDs 44. A certain gap is provided between the blue LED light source 40 and the diffuser plate 42 by the spacer 52.
The processed evaluation wavelength conversion member 54 is arranged on the diffuser plate 42 of the evaluation device A, and the processed evaluation wavelength is arranged at an angle within ± 10 ° with respect to the line L orthogonal to the surface of the diffuser plate 42. The conversion member 54 was visually observed and evaluated.
Further, in the evaluation device B shown in FIG. 5, a pair of prism sheets 56A and a prism sheet 56B are further placed on the evaluation device A so that the groove directions of the prism sheets are orthogonal to each other on the processed wavelength conversion member 54 for evaluation. It is arranged like this.
(conditions)
Condition 5B: The wavelength conversion member was allowed to stand for 500 hours in a constant temperature and humidity chamber set under the conditions of 85 ° C. and 5% RH.
(Standard)
Lv1: No black spot defect is observed even in the evaluation device A.
Lv2: Black spot defect is observed in the evaluation device A, but no black spot defect is observed in the evaluation device B.
Lv3: Black spot defects are also observed in the evaluation device B.
The results obtained are shown in Table 2.

From the evaluation results of Tables 1 and 2, the wavelength conversion member formed from the wavelength conversion resin composition of the example containing the compound having a carboxy group and a thiol group in one molecule has a carboxy group in one molecule. It can be seen that the decrease in the emission intensity of the quantum dot phosphor is suppressed as compared with the wavelength conversion member formed from the wavelength conversion resin composition of the comparative example which does not contain the compound having the thiol group and the thiol group.

All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims

A resin composition for wavelength conversion containing a polyfunctional (meth) acrylate compound having an alicyclic structure, a polyfunctional thiol compound, a compound having a carboxy group and a thiol group in one molecule, a photopolymerization initiator, and a quantum dot phosphor. ..
The resin composition for wavelength conversion according to claim 1, wherein the compound having a carboxy group and a thiol group in one molecule contains two or less carboxy groups.
The resin composition for wavelength conversion according to claim 1 or 2, wherein the compound having a carboxy group and a thiol group in one molecule contains two or less thiol groups.
The wavelength conversion resin composition according to any one of claims 1 to 3, wherein at least one of the thiol groups contained in the compound having a carboxy group and a thiol group in one molecule is a primary thiol group. ..
The wavelength conversion resin composition according to any one of claims 1 to 4, wherein the compound having a carboxy group and a thiol group in one molecule has a molecular weight of 80 to 300.
The wavelength conversion resin composition according to any one of claims 1 to 5, wherein the compound having a carboxy group and a thiol group in one molecule is an aliphatic compound.
The resin composition for wavelength conversion according to any one of claims 1 to 6, which contains a monofunctional (meth) acrylate compound.
The resin composition for wavelength conversion according to any one of claims 1 to 7, which does not contain a liquid medium or has a liquid medium content of 0.5% by mass or less.
The wavelength conversion resin composition according to any one of claims 1 to 8, which contains a white pigment.
A cured resin for wavelength conversion, which is a cured product of the resin composition for wavelength conversion according to any one of claims 1 to 9.
The cured resin for wavelength conversion according to claim 10, wherein the glass transition temperature measured by dynamic viscoelasticity measurement is 85 ° C. or higher.
A wavelength conversion member having the cured resin for wavelength conversion according to any one of claims 10 and 11.
The wavelength conversion member according to claim 12, further comprising a coating material that covers at least a part of the cured resin for wavelength conversion.
The wavelength conversion member according to claim 12 or 13, which is in the form of a film.
The wavelength conversion member according to any one of claims 12 to 14, which is for displaying an image.
A backlight unit including the wavelength conversion member according to any one of claims 12 to 15, and a light source.
An image display device including the backlight unit according to claim 16.