Photosensitive resin composition

Abstract

To provide a photosensitive resin composition allowing high-purity recovery of a wavelength conversion material from a developing waste solution and enabling formation of a wavelength conversion layer resistant to degradation of luminescent properties due to heat.SOLUTION: The photosensitive resin composition includes a photosensitive resin containing a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, a modified silicone-based dispersant, and an organic solvent, and an inorganic fluorescent material dispersed in the photosensitive resin, the inorganic fluorescent material emitting red, green, or blue fluorescence.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photosensitive resin composition. [Background technology]

[0002] Some display devices, such as micro LED (light-emitting diode) displays and organic electroluminescence (EL) displays, include a wavelength conversion layer that converts light emitted from a light source into light of a different wavelength. For example, some micro LED displays can display multicolor images by combining an LED that emits light in the near-ultraviolet to blue wavelength range with two or more wavelength conversion layers that convert this light into light of other wavelengths.

[0003] Patent Document 1 describes the formation of a wavelength conversion layer from a photosensitive resin composition containing a pyrromethene derivative as a wavelength converting material, a photopolymerizable compound, a photopolymerization initiator having an h-line absorption coefficient of 100 mL / g cm or more, and an alkali-soluble resin. This document lists acrylic resins, epoxy resins, polyimide resins, urethane resins, urea resins, polyvinyl alcohol resins, polyamide resins, polyamideimide resins, and polyester resins as examples of the photopolymerizable compound. This document also describes that the photosensitive resin composition may further contain a dispersant, and lists examples of dispersants that may be used, including low-molecular-weight dispersants such as pigment intermediates and pigment derivatives, as well as polymers such as polyesters, polyalkylamines, polyimines, polyamides, polyurethanes, polyacrylates, polyimides, and polyamideimides, and copolymers thereof. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 181698 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have discovered the following facts regarding the process of forming a wavelength converting layer using a photosensitive resin composition containing a wavelength converting material.

[0006] That is, in a process for forming a wavelength converting layer using a photosensitive resin composition containing a wavelength converting material, if the wavelength converting material is an inorganic phosphor, the wavelength converting material can be recovered from the waste liquid generated during development. However, if the alkali-soluble resin is a silicone-based resin, the wavelength converting material recovered from the waste liquid will contain a non-negligible amount of silicone-based resin.

[0007] When an acrylic resin, a urethane resin, or another resin is used as the alkali-soluble resin instead of the silicone resin, it is possible to prevent a non-negligible amount of the silicone resin from being mixed into the recovered wavelength converting material. However, a wavelength converting layer formed from a photosensitive resin composition whose composition has been changed as described above suffers from significant deterioration in light-emitting properties due to heat.

[0008] An object of the present invention is to provide a photosensitive resin composition that enables recovery of a wavelength converting material with high purity from developer waste solution and enables formation of a wavelength converting layer that is less susceptible to deterioration of light-emitting properties due to heat. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a photosensitive resin composition comprising: a photosensitive resin including a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, a modified silicone dispersant, and an organic solvent; and an inorganic phosphor that emits red, green, or blue fluorescence and is dispersed in the photosensitive resin.

[0010] According to another aspect of the present invention, there is provided the photosensitive resin composition according to the above aspect, wherein the modified silicone-based dispersant is an aliphatic modified silicone.

[0011] According to yet another aspect of the present invention, there is provided the photosensitive resin composition according to any of the above aspects, wherein the acrylic resin is a copolymer containing a structural unit having an N-(cyclohexyl)succinimide skeleton and a structural unit having a glutaric anhydride skeleton.

[0012] According to yet another aspect of the present invention, there is provided the photosensitive resin composition according to any one of the above aspects, wherein the photopolymerizable compound contains a tri- or higher functional (meth)acrylate compound.

[0013] According to yet another aspect of the present invention, there is provided a photosensitive resin composition according to any of the above aspects, comprising the inorganic phosphor in an amount of 10 to 80 parts by mass relative to 100 parts by mass of a total solid content, and comprising, relative to 100 parts by mass of a total solid content excluding the inorganic phosphor, the photopolymerizable compound in an amount of 1 to 80 parts by mass, the photopolymerization initiator in an amount of 0.1 to 10 parts by mass, the acrylic resin in an amount of 5 to 60 parts by mass, and the modified silicone dispersant in an amount of 1 to 50 parts by mass.

[0014] According to yet another aspect of the present invention, there is provided a wavelength conversion layer comprising a cured product of the photosensitive resin composition according to any of the above aspects.

[0015] According to yet another aspect of the present invention, there is provided an article comprising the wavelength converting layer according to the above aspect.

[0016] According to yet another aspect of the present invention, there is provided an article according to the above aspect, which is a wavelength conversion substrate. Alternatively, according to yet another aspect of the present invention, there is provided an article according to the above aspect, which is a display device.

[0017] According to yet another aspect of the present invention, there is provided a phosphor dispersion liquid for use in preparing the photosensitive resin composition according to any of the above aspects, the phosphor dispersion liquid comprising an inorganic phosphor that emits red, green, or blue fluorescence, a modified silicone-based dispersant, and an organic solvent.

[0018] According to yet another aspect of the present invention, there is provided the phosphor dispersion liquid according to the above aspect, wherein the modified silicone-based dispersant is an aliphatic modified silicone.

[0019] According to yet another aspect of the present invention, there is provided the phosphor dispersion liquid according to any one of the above aspects, further containing an acrylic resin.

[0020] According to yet another aspect of the present invention, there is provided a phosphor dispersion liquid according to the above aspect, wherein the acrylic resin contains a unit having an N-(cyclohexyl)succinimide skeleton and a unit having a glutaric anhydride skeleton. [Effects of the Invention]

[0021] According to the present invention, there is provided a photosensitive resin composition that enables recovery of a luminescent material with high purity from developer waste solution and enables formation of a wavelength conversion layer that is less susceptible to deterioration of luminescent properties due to heat. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a cross-sectional view showing a display device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects, either singly or in combination.

[0024] Furthermore, the embodiments shown below are merely examples of configurations for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited by the materials, shapes, structures, etc. of the components described below. Various modifications can be made to the technical idea of ​​the present invention within the technical scope defined by the claims.

[0025] In the drawings, elements having the same or similar functions are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, the drawings are schematic, and the relationship between dimensions in one direction and dimensions in another direction, and the relationship between the dimensions of one member and the dimensions of another member, etc. may differ from the actual relationship.

[0026] <1> Examples of wavelength conversion layer applications Fig. 1 is a cross-sectional view showing a display device according to one embodiment of the present invention. The display device 1 shown in Fig. 1 is an example of an article containing a wavelength converting material. The display device 1 is a micro LED display capable of color display using an active matrix driving method, in which each sub-pixel contains a light-emitting diode (LED).

[0027] 1, the X direction and the Y direction are parallel to the display surface of the display device 1 and intersect with each other. According to one example, the X direction and the Y direction are perpendicular to each other. The Z direction is perpendicular to the X direction and the Y direction. That is, the Z direction is the thickness direction of the display device 1.

[0028] The display device 1 shown in FIG. 1 includes a light control device 2, a wavelength conversion substrate 3, and an adhesive layer 4.

[0029] The light control device 2 is a device that emits light toward the wavelength conversion substrate 3 and is capable of adjusting at least one of the intensity of the light and the time for emitting the light for each pixel or each subpixel. The light control device 2 includes a substrate 21, a multilayer wiring layer 22, and a light-emitting diode 23.

[0030] The substrate 21 includes, for example, an insulating substrate such as a glass substrate. The substrate 21 may further include an undercoat layer provided on the main surface of the insulating substrate facing the wavelength conversion substrate 3. The undercoat layer is, for example, a laminate of a silicon nitride layer and a silicon oxide layer sequentially stacked on the insulating substrate. The substrate 21 may be a semiconductor substrate such as a silicon substrate. The substrate 21 may be rigid or flexible.

[0031] The multilayer wiring layer 22 is provided on the main surface of the substrate 21 facing the wavelength conversion substrate 3. The multilayer wiring layer 22 includes video signal lines, first power supply lines, second power supply lines, scanning signal lines, pixel circuits, and an interlayer insulating film.

[0032] The video signal lines each extend in the Y direction and are arranged in the X direction. The scanning signal lines each extend in the X direction and are arranged in the Y direction. The first and second power supply lines each extend in the Y direction and are arranged in the X direction in correspondence with the video signal lines. The first and second power supply lines may each extend in the X direction and be arranged in the Y direction in correspondence with the scanning signal lines. Alternatively, one of the first and second power supply lines may each extend in the Y direction and be arranged in the X direction in correspondence with the video signal lines, and the other may each extend in the X direction and be arranged in the Y direction in correspondence with the scanning signal lines.

[0033] The pixel circuits are arranged in the X and Y directions on the main surface of the substrate 21. Each pixel circuit includes a drive control element, a switch, and a capacitor. The drive control element is, for example, a p-channel field effect transistor having a source connected to a first power supply line. The switch is, for example, an n-channel field effect transistor having a gate connected to a scanning signal line, a source connected to a video signal line, and a drain connected to the gate of the drive control element. The capacitor is, for example, a thin-film capacitor having one electrode connected to the gate of the drive control element and the other electrode connected to the first power supply line. The pixel circuits may have other configurations.

[0034] The light-emitting diode 23 has a multi-layer structure. Here, the stacking direction of the layers included in the light-emitting diode 23 is the Z direction. This stacking direction may be perpendicular to the Z direction.

[0035] The light emitting diodes 23 have the same emission spectrum. The light emitting diodes 23 emit light of short wavelengths such as blue light and ultraviolet light. Here, as an example, the light emitting diodes 23 are assumed to be blue light emitting diodes that emit blue light.

[0036] The light emitting diodes 23 are arranged corresponding to the pixel circuits on the multi-layer wiring layer 22. The anode of each of the light emitting diodes 23 is connected to the drain of the drive control element, and the cathode is connected to the second power supply line.

[0037] The wavelength conversion board 3 faces the light control device 2. Specifically, the wavelength conversion board 3 faces the board 21 with the light emitting diode 23 and the like sandwiched therebetween.

[0038] The wavelength conversion substrate 3 includes a transparent substrate 31, a black matrix 32, a partition layer 34, a color filter including a first colored layer 33R and a second colored layer 33G, a base layer 33B, a first wavelength conversion layer 36R, a second wavelength conversion layer 36G, and a filling layer 36B.

[0039] The transparent substrate 31 is transparent to visible light. The transparent substrate 31 is, for example, a colorless substrate. The transparent substrate 31 may have a single-layer structure or a multi-layer structure. The transparent substrate 31 is made of, for example, glass, transparent resin, or a combination thereof. The transparent substrate 31 may be rigid or flexible. The transparent substrate 31 has a first main surface facing the light control device 2 and a second main surface that is the rear surface of the first main surface.

[0040] The black matrix 32 is provided on the first main surface of the transparent substrate 31. The black matrix 32 is a black layer that blocks visible light. The black matrix 32 is made of, for example, a mixture containing a binder resin and a colorant. The colorant is, for example, a black pigment or a mixture of pigments that exhibit black through subtractive color mixing, for example, a mixture containing a blue pigment, a green pigment, and a red pigment.

[0041] The black matrix 32 has first through holes at the positions of the light emitting diodes 23. The opening of each first through hole on the transparent substrate 31 side has a larger dimension in the direction perpendicular to the Z direction than the light emitting diodes 23.

[0042] The first colored layer 33R, the second colored layer 33G, and the underlayer 33B form a stripe arrangement on the transparent substrate 31 provided with the black matrix 32. These form a plurality of pixels, each consisting of the first colored layer 33R, the second colored layer 33G, and the underlayer 33B, and these pixels are arranged in the X and Y directions.

[0043] As described above, here, the first colored layer 33R is a red colored layer, and the second colored layer 33G is a green colored layer. Here, the base layer 33B is a colorless light-transmitting layer or a blue colored layer. Each of the first colored layers 33R fills one of the first through holes. Each of the second colored layers 33G fills another of the first through holes. Each of the base layers 33B fills yet another of the first through holes.

[0044] The partition wall layer 34 is provided on a composite film including the first colored layer 33R, the second colored layer 33G, and the base layer 33B. According to one example, the partition wall layer 34 is transparent. In this case, the partition wall layer 34 may be colored or colorless. The partition wall layer 34 may have light scattering properties.

[0045] The partition layer 34 has second through holes at the positions of the first through holes, respectively. Here, the second through holes are provided so that the outline of the orthogonal projection of the opening on the transparent substrate 31 side onto the first main surface (hereinafter referred to as the second outline) surrounds the outline of the orthogonal projection of the first through hole onto the first main surface (hereinafter referred to as the first outline). The second outline does not have to surround the first outline. In a structure in which the second outline surrounds the first outline, the effect of stray light on display is smaller than in a structure in which the second outline does not surround the first outline.

[0046] The portion of the partition layer 34 that is sandwiched between adjacent second through holes has a rectangular cross-sectional shape. This portion may have a forward tapered cross-sectional shape, a reverse tapered cross-sectional shape, or another cross-sectional shape.

[0047] The partition wall layer 34 may have a multi-layer structure. For example, the partition wall layer 34 may include a resin layer and a reflective layer that covers at least a part of the surface of the resin layer.

[0048] The reflective layer may have a single-layer structure or a multi-layer structure. The layers included in the reflective layer are, for example, metals, alloys, or transparent dielectrics. The reflective layer made of a metal or alloy is, for example, made of aluminum or an aluminum alloy.

[0049] The first wavelength conversion layer 36R is provided on the first colored layer 33R. The first wavelength conversion layer 36R is a layer containing an inorganic phosphor and a transparent resin. Here, the first wavelength conversion layer 36R converts the blue light emitted by the light emitting diode 23 into red light. That is, here, the inorganic phosphor contained in the first wavelength conversion layer 36R emits red fluorescence.

[0050] The second wavelength conversion layer 36G is provided on the second colored layer 33G. The second wavelength conversion layer 36G is a layer containing a phosphor such as an inorganic phosphor and a transparent resin. Here, the second wavelength conversion layer 36G converts the blue light emitted by the light-emitting diode 23 into green light. That is, here, the inorganic phosphor contained in the second wavelength conversion layer 36G emits green fluorescence.

[0051] The filling layer 36B is provided on the base layer 33B. As described above, the filling layer 36B is a colorless and transparent layer. In this case, the filling layer 36B is made of, for example, a transparent resin.

[0052] When the light-emitting diode 23 is an ultraviolet light-emitting diode, the filling layer 36B is a third wavelength conversion layer. The third wavelength conversion layer is a layer containing a phosphor such as an inorganic phosphor and a transparent resin. The third wavelength conversion layer converts, for example, ultraviolet light emitted by the ultraviolet light-emitting diode into blue light. In this case, the first wavelength conversion layer 36R and the second wavelength conversion layer 36G convert the ultraviolet light emitted by the ultraviolet light-emitting diode into red light and green light, respectively. That is, in this case, the inorganic phosphor contained in the first wavelength conversion layer 36R, the inorganic phosphor contained in the second wavelength conversion layer 36G, and the inorganic phosphor contained in the third wavelength conversion layer emit red, green, and blue fluorescent light, respectively.

[0053] The adhesive layer 4 is interposed between the light control device 2 and the wavelength conversion substrate 3, and bonds them together. The adhesive layer 4 transmits light emitted by the light-emitting diodes 23. The adhesive layer 4 is, for example, a colorless and transparent layer. The adhesive layer 4 is made of an adhesive or a pressure-sensitive adhesive.

[0054] The display device 1 described above is a micro LED display containing an inorganic phosphor as a wavelength converting material. The article containing an inorganic phosphor as a wavelength converting material may be other display devices. For example, the article containing an inorganic phosphor as a wavelength converting material may be an organic electroluminescence (EL) display. Alternatively, the article containing an inorganic phosphor as a wavelength converting material may be a liquid crystal display. In this case, the wavelength converting material may be used, for example, in a backlight.

[0055] An article containing an inorganic phosphor as a wavelength converting material may be a device other than a display device. For example, an article containing an inorganic phosphor as a wavelength converting material may be a wavelength converting substrate that can be used as part of a display device. Alternatively, an article containing an inorganic phosphor as a wavelength converting material may be a lighting device.

[0056] <2> Display device manufacturing method An example of a method for manufacturing the above-described display device 1 will now be described.

[0057] First, a structure including a transparent substrate 31, a black matrix 32, a first colored layer 33R, a second colored layer 33G, a base layer 33B, and a partition layer 34 is prepared. Next, a first wavelength conversion layer 36R, a second wavelength conversion layer 36G, and a filling layer 36B are formed. The first wavelength conversion layer 36R, the second wavelength conversion layer 36G, and the filling layer 36B may be formed in any order.

[0058] The first wavelength conversion layer 36R and the second wavelength conversion layer 36G are each formed by, for example, the following method.

[0059] First, a photosensitive resin composition containing a wavelength converting material and a photosensitive resin is prepared. The photosensitive resin may be either a negative or positive type. The composition of the photosensitive resin composition will be described in detail later.

[0060] Next, a photosensitive resin composition is applied to the structure to form a photosensitive layer. The photosensitive layer is then partially exposed to light. If the photosensitive resin is a negative type, the region of the photosensitive layer corresponding to the wavelength conversion layer to be formed is exposed to light. If the photosensitive resin is a positive type, the region of the photosensitive layer other than the region corresponding to the wavelength conversion layer to be formed is exposed to light.

[0061] Next, the exposed photosensitive layer is spray-developed. For example, if the photosensitive resin is a negative type, the unexposed portions of the photosensitive layer are removed by this spray development. Alternatively, if the photosensitive resin is a positive type, the exposed portions of the photosensitive layer are removed by this spray development.

[0062] In this spray development, inorganic alkalis such as sodium carbonate, sodium bicarbonate, and sodium hydroxide, or aqueous solutions of tetramethylammonium hydroxide (TMAH) are generally used as the developer. Here, a developer containing carbonate ions is used.

[0063] When spray development is used to develop the pattern-exposed photosensitive layer, the portion of the photosensitive layer that should be removed by development can be finely crushed, making it possible to remove impurities from the wavelength converting material by filtration.

[0064] The photosensitive layer is then heated to harden it, thus forming the first wavelength conversion layer 36R and the second wavelength conversion layer 36G.

[0065] The filling layer 36B can be formed by the same method as the first wavelength conversion layer 36R and the second wavelength conversion layer 36G, except that, for example, a photosensitive resin composition that does not contain the wavelength conversion material is used and the wavelength conversion material is not recovered. Furthermore, when the filling layer 36B is the third wavelength conversion layer, it can be formed by the same method as the first wavelength conversion layer 36R and the second wavelength conversion layer 36G.

[0066] In this way, the wavelength conversion substrate 3 is obtained. Next, the wavelength conversion substrate 3 and the separately prepared light control device 2 are bonded together via the adhesive layer 4. In this way, the display device 1 shown in FIG. 1 is obtained.

[0067] While the display device 1 is manufactured as described above, solids are recovered from the waste liquid generated in the spray development by filtration or the like. Then, the solids are thoroughly washed to obtain a wavelength converting material. The wavelength converting material recovered in this way can be reused in the manufacture of the display device 1.

[0068] <3> Photosensitive resin composition The wavelength conversion layer is made of a cured product of a photosensitive resin composition. This photosensitive resin composition contains a wavelength converting material and a photosensitive resin. Specifically, the photosensitive resin composition contains a photosensitive resin containing a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, a modified silicone dispersant, and an organic solvent, and an inorganic phosphor that emits red, green, or blue fluorescence and is dispersed in the photosensitive resin.

[0069] <3.1> Wavelength conversion materials As described above, the wavelength conversion material is an inorganic phosphor that emits red, green, or blue fluorescence. The inorganic phosphor is a phosphor containing a metal element such as Sr, Ca, Al, Si, Eu, Ba, or Mg. The inorganic phosphor includes not only unagglomerated particles but also particle agglomerates.

[0070] An example of an inorganic phosphor that emits red fluorescence is 2+ (M is Sr or a combination of Sr and one or more selected from Mg, Ca and Ba, and Eu 2+ represents the luminescent center). An example of an inorganic phosphor that emits blue fluorescence is represented by the general formula (Ba, Sr, Ca, Mg) 10 An example of an inorganic phosphor that emits green fluorescence is the phosphor particles containing crystals represented by the general formula MGa2S4:Eu 2+ (M is one or more selected from Sr, Ba and Ca, and Eu 2+ represents a luminescent center). The phosphor particles may be coated with an oxide film containing one or more oxides of Si, Al, Ti, Zr, Sn, and Zn, or may be coated with a film made of phosphate.

[0071] The particle size distribution of inorganic phosphors measured by laser diffraction and scattering method is, for example, the difference W between the maximum particle diameter and the minimum particle diameter. orig is in the range of 1 to 20 μm, and the volume-based median diameter D 50 The particle size distribution of the inorganic phosphor measured by a laser diffraction / scattering method is preferably such that the median diameter D is in the range of 3.5 to 4.5 μm in the volume-based cumulative distribution. 50 and a 90% diameter D in the range of 7.0 to 8.4 μm. 90 It has the following characteristics.

[0072] When the thickness of the partition wall layer 34, i.e., the height of the partition walls, is within the range of 10 to 50 μm, the particle diameter of the inorganic phosphor is preferably 0.7 times or less the height of the partition walls. If the inorganic phosphor contains aggregates, the aggregates can be at least partially eliminated by using ultrasonic or vibration stirring before coating the photosensitive resin composition. If excessively large particles overlap in the thickness direction within the space surrounded by the partition walls, the wavelength conversion layer may protrude from the partition wall layer 34.

[0073] The photosensitive resin composition preferably contains 10 to 80 parts by mass, and more preferably 30 to 70 parts by mass, of the inorganic phosphor relative to 100 parts by mass of the total solid content of the photosensitive resin composition.

[0074] <3.2> Photosensitive resin The photosensitive resin contains a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, a modified silicone dispersant, and an organic solvent.

[0075] <3.2.1> Photopolymerizable compounds The photopolymerizable compound is a resin that polymerizes and hardens when irradiated with active energy rays such as ultraviolet rays. As the photopolymerizable compound, for example, a monofunctional, difunctional, or trifunctional or higher functional (meth)acrylate monomer can be used.

[0076] In this specification, "(meth)acrylate" is a general term for both acrylate and methacrylate, and "(meth)acryloyl" is a general term for both acryloyl and methacryloyl.

[0077] Examples of monofunctional (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isobornyl (meth)acrylate. acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phosphate (meth)acrylate, ethylene oxide-modified phosphate (meth)acrylate, phenoxy (meth)acrylate, ethylene oxide-modified phenoxy (meth)acrylate, propylene oxide Oxide-modified phenoxy (meth)acrylate, nonylphenol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, propylene oxide-modified nonylphenol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, p) acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, 2-adamantane,Examples include adamantane derivative mono(meth)acrylates such as adamantyl acrylate having a monovalent mono(meth)acrylate derived from adamantanediol.

[0078] Examples of bifunctional (meth)acrylate compounds include di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and hydroxypivalic acid neopentyl glycol di(meth)acrylate.

[0079] Examples of trifunctional or higher (meth)acrylate compounds include tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris(2-hydroxyethylisocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, etc., trifunctional (meth)acrylate compounds such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate. and polyfunctional (meth)acrylate compounds having three or more functional groups such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane hexa(meth)acrylate, as well as polyfunctional (meth)acrylate compounds in which a portion of these (meth)acrylates is substituted with an alkyl group or ε-caprolactone.

[0080] Urethane (meth)acrylates can also be used as photopolymerizable compounds. Examples of urethane (meth)acrylates include those obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer, and then reacting the resulting product with a (meth)acrylate monomer having a hydroxyl group.

[0081] Examples of urethane (meth)acrylates include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

[0082] The above-mentioned (meth)acrylate compounds may be used alone or in combination of two or more thereof. In addition, the above-mentioned (meth)acrylate compounds may be monomers in the photosensitive resin composition, or may be partially polymerized oligomers.

[0083] As the photopolymerizable compound, it is preferable to use a trifunctional or higher (meth)acrylate compound such as tris(2-acryloyloxyethyl) isocyanurate, for example, a trifunctional (meth)acrylate compound.

[0084] The photosensitive resin composition preferably contains 1 to 80 parts by mass, more preferably 10 to 60 parts by mass, of the photopolymerizable compound relative to 100 parts by mass of the total solids content excluding the inorganic phosphor. Increasing the content of the photopolymerizable compound further increases the transparency of the wavelength conversion layer. However, excessively increasing the content of the photopolymerizable compound reduces the handleability of the photosensitive resin or photosensitive resin composition.

[0085] <3.2.2> Photopolymerization initiator A photopolymerization initiator is a compound that generates radicals when irradiated with ultraviolet light.

[0086] Examples of the photopolymerization initiator include benzoins, such as benzoin or benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; phenyl ketones, such as acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; alkyl phenyl ketones such as 2-hydroxy-2-methylpropiophenone; and cycloalkyl phenyl ketones such as 1-hydroxycyclohexyl phenyl ketone; aminoacetophenones, such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinoaminopropanone-1,2-benzyl-2-dimethylphenyl ketone; anthraquinones such as anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, or 1-chloroanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, or 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal or benzil dimethyl ketal; benzophenones such as benzophenone; xanthones; phosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and oxime esters such as 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime).

[0087] These photopolymerization initiators may be used alone or in combination of two or more. As the polymerization initiator, it is preferable to use oxime esters such as 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime).

[0088] The photosensitive resin composition preferably contains 0.1 to 10 parts by mass, more preferably 0.5 to 6 parts by mass, of the photopolymerization initiator relative to 100 parts by mass of the total solids content excluding the inorganic phosphor. Increasing the content of the photopolymerization initiator allows for more reliable curing of the coating film made of the photosensitive resin composition. Furthermore, unless the content of the photopolymerization initiator is excessively high, a decrease in the transparency of the wavelength conversion layer due to residual unreacted photopolymerization initiator is unlikely to occur.

[0089] <3.2.3> Acrylic resins The acrylic resin is, for example, one or more of polymethacrylate, polyacrylate, polyacrylonitrile, and polyacrylamide. The acrylic resin is preferably a copolymer containing a structural unit having an N-(cyclohexyl)succinimide skeleton and a structural unit having a glutaric anhydride skeleton.

[0090] The photosensitive resin composition preferably contains 5 to 60 parts by mass of acrylic resin, and more preferably 30 to 60 parts by mass, per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0091] <3.2.4> Modified silicone dispersants Modified silicone dispersants are primarily composed of modified silicone compounds with a structure in which a substituent has been introduced into a portion of the silicone, whose main skeleton is a siloxane bond in which silicon and oxygen are alternately linked by chemical bonds. Examples of modified silicone dispersants include aliphatic modified silicones and aromatic modified silicones.

[0092] Examples of aliphatic-modified silicones include silicones having side chains such as polyester and polyether. The number of carbon atoms constituting the side chain of the aliphatic-modified silicone is preferably in the range of 1 to 10. The main chain of the aliphatic-modified silicone may be linear, branched, or cyclic.

[0093] Commercially available aliphatic modified silicones can be used. Examples of commercially available aliphatic modified silicones include KR-5230, KR-5234, and KR-5235 (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK (registered trademark)-313 and BYK (registered trademark)-302 (manufactured by BYK-Chemie), and TSR180 (manufactured by Momentive Performance Materials Japan, LLC).

[0094] Examples of aromatic modified silicones include aromatic polyester modified silicones and semi-aromatic polyester modified silicones. Commercially available aromatic modified silicones can be used. Examples of aromatic modified silicones include BYK®-322 and BYK®-323 (manufactured by BYK-Chemie); KR-112, KR-211, KR-212, KR-255, KR-271, KR-282, KR-300, KR-311, KR-2621-1, X-40-2667A, and KR-480 (manufactured by Shin-Etsu Chemical Co., Ltd.); SILIKOFTAL® HTT (manufactured by Evonik); and TSR116, TSR117, TSR144, and YR47 (manufactured by Momentive Performance Materials Japan LLC). Among these, aliphatic modified silicones are preferred.

[0095] The photosensitive resin composition preferably contains 1 to 50 parts by mass of the modified silicone-based dispersant, and more preferably 5 to 30 parts by mass, per 100 parts by mass of the total solids content excluding the inorganic phosphor.

[0096] <3.2.5> Organic solvents Examples of organic solvents include ethers, ketones, esters, and cellosolves. Examples of ethers include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole, and phenetole. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and ethylcyclohexanone. Examples of esters include ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone. Examples of cellosolves include methyl cellosolve, cellosolve (ethyl cellosolve), butyl cellosolve, cellosolve acetate, etc. The organic solvents may be used alone or in combination of two or more.

[0097] <3.3> Method for preparing photosensitive resin composition The photosensitive resin composition can be prepared, for example, by mixing a phosphor dispersion liquid and a liquid photoresist. The phosphor dispersion liquid is, for example, a liquid containing an inorganic phosphor, a modified silicone-based dispersant, and an organic solvent. The phosphor dispersion liquid may further contain an acrylic resin. The liquid photoresist is, for example, a liquid containing a photopolymerizable compound and a photopolymerization initiator. The liquid photoresist may further contain an acrylic resin. The photosensitive resin composition may be prepared by adding the components of the liquid photoresist described above to the phosphor dispersion liquid.

[0098] <4> effect The photosensitive resin composition contains an acrylic resin instead of a silicone resin. Therefore, the developer waste generated in the process of forming a wavelength converting layer using this photosensitive resin composition does not contain a large amount of silicone resin, and the wavelength converting material recovered from this developer waste does not contain a significant amount of silicone resin. Therefore, the photosensitive resin composition makes it possible to recover the wavelength converting material with high purity from the developer waste.

[0099] Furthermore, the photosensitive resin composition uses a modified silicone-based dispersant as a dispersant. A wavelength conversion layer obtained from a photosensitive resin composition containing an acrylic resin instead of a silicone-based resin and a dispersant other than the modified silicone-based dispersant exhibits significant deterioration in luminescence characteristics due to heat. In contrast, the photosensitive resin composition containing a modified silicone-based dispersant can produce a wavelength conversion layer that is less susceptible to deterioration in luminescence characteristics due to heat, despite containing an acrylic resin instead of a silicone-based resin.

[0100] That is, the photosensitive resin composition enables the wavelength converting material to be recovered with high purity from waste developer, and enables the formation of a wavelength converting layer that is less susceptible to deterioration of light-emitting properties due to heat. [Example]

[0101] The following describes tests carried out in connection with the present invention.

[0102] (1) Test A (1.1) Formation of wavelength conversion layer (1.1.1) Example 1A A phosphor dispersion liquid was prepared by dispersing an inorganic phosphor in a mixed liquid containing a dispersant and an organic solvent. To this phosphor dispersion liquid, a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, and an organic solvent were added as liquid photoresist components. The resulting liquids were mixed to obtain a photosensitive resin composition.

[0103] Here, the inorganic phosphor is selected from the group consisting of Sr 0.01-1.2Ca 0.01-1.2 Al 0.8-1.2 Si 0.8-1.2 N 2.0-4.0 :EU 0.01-0.2 The volumetric median diameter D 50 A red phosphor with a diameter of 5.7 μm was used. Tris(2-acryloyloxyethyl) isocyanurate was used as the photopolymerizable compound. 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime) (photopolymerization initiator A) was used as the photopolymerization initiator. A copolymer (acrylic resin A) containing a structural unit having an N-(cyclohexyl)succinimide skeleton and a structural unit having a glutaric anhydride skeleton was used as the acrylic resin. BYK (registered trademark)-313 (manufactured by BYK-Chemie; modified silicone-based dispersant CL), a polyester-modified silicone-based dispersant, was used as the dispersant. Propylene glycol monomethyl ether acetate (PGMAc) was used as the organic solvent.

[0104] The total solid content of the photosensitive resin composition was 56.2% by mass. The amount of inorganic phosphor was 53.4 parts by mass per 100 parts by mass of the total solid content. The amount of photopolymerizable compound A was 35.5 parts by mass, the amount of photopolymerization initiator A was 3.8 parts by mass, the amount of acrylic resin A was 47.3 parts by mass, and the amount of modified silicone dispersant CL was 13.4 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0105] Next, the photosensitive resin composition was applied to a glass substrate by spin coating to form a photosensitive layer, which was then left to stand for 5 minutes, dried in a vacuum dryer, and then pre-baked at 100°C for 3 minutes.

[0106] Next, the entire surface of the photosensitive layer was exposed to ihg rays at an exposure dose of 200 mJ / cm 2 The photosensitive layer was then subjected to shower development using an aqueous sodium hydroxide solution, followed by baking in air at 230°C for 20 minutes to obtain a wavelength conversion layer having a thickness of approximately 20 μm.

[0107] (1.1.2) Example 2A A wavelength conversion layer was formed in the same manner as in Example 1A, except that the following photosensitive resin composition was used.

[0108] Here, the inorganic phosphor and dispersant used were the same as those used in Example 1A. Bisphenol A-EO 3.8 mol adduct diacrylate (photopolymerizable compound C) was used as the photopolymerization compound. 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (polymerization initiator B) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (polymerization initiator C) were used as the photopolymerization initiators. Polymethacrylate, polyurethane, and a copolymer containing an acrylate group (acrylic resin B) were used as the acrylic resin. Propylene glycol monomethyl ether acetate (PGMAc) was used as the organic solvent.

[0109] The total solid content of the photosensitive resin composition was 52.7% by mass. The amount of inorganic phosphor was 56.9 parts by mass per 100 parts by mass of the total solid content. The amount of photopolymerizable compound C was 33.5 parts by mass, the amount of photopolymerization initiator B was 3.5 parts by mass, the amount of photopolymerization initiator C was 3.5 parts by mass, the amount of acrylic resin B was 44.1 parts by mass, and the amount of modified silicone dispersant CL was 15.4 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0110] (1.1.3) Example 3A A wavelength conversion layer was formed in the same manner as in Example 1A, except that the following photosensitive resin composition was used.

[0111] Here, the inorganic phosphor, photopolymerization initiator, and dispersant used were the same as those used in Example 1A. The photopolymerizable compound used was a diacrylate of bisphenol A ethylene oxide adduct (photopolymerizable compound B). The acrylic resin used was an acrylic resin containing tris(2-acryloyloxyethyl) isocyanurate (acrylic resin C). The organic solvent used was propylene glycol monomethyl ether acetate (PGMAc).

[0112] The total solid content of the photosensitive resin composition was 62.3% by mass. The amount of inorganic phosphor was 48.2 parts by mass per 100 parts by mass of the total solid content. The amount of photopolymerizable compound B was 36.5 parts by mass, the amount of photopolymerization initiator A was 4.0 parts by mass, the amount of acrylic resin C was 48.6 parts by mass, and the amount of modified silicone dispersant CL was 10.8 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0113] (1.1.4) Reference example A wavelength conversion layer was formed in the same manner as in Example 1A, except that the following photosensitive resin composition was used.

[0114] Here, the inorganic phosphor used was the same as that used in Example 1A. Tris[2-(acryloyloxy)ethyl]isocyanurate (polymerizable compound D) was used as the photopolymerizable compound. 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (OMNIRAD (registered trademark)-907 manufactured by IGM Resins; photopolymerization initiator D) was used as the photopolymerization initiator. Instead of the acrylic resin, a siloxane-based resin containing a fully caged silsesquioxane, which is a silicone-based resin, was used. Modified silicone-based dispersant CL was used as the dispersant. Propylene glycol monomethyl ether acetate (PGMAc) was used as the organic solvent.

[0115] The total solid content of the photosensitive resin composition was 54.2% by mass. The amount of inorganic phosphor was 55.4 parts by mass per 100 parts by mass of the total solid content. The amount of photopolymerizable compound was 38.4 parts by mass, the amount of photopolymerization initiator was 4.1 parts by mass, the amount of silicone-based resin was 43.0 parts by mass, and the amount of dispersant was 14.5 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0116] (1.2) Evaluation The wavelength conversion layers of Examples 1A to 3A and the Reference Example were observed under a microscope, and it was found that they all had a uniform thickness and a flat surface.

[0117] Next, the emission characteristics of the wavelength conversion layers of Examples 1A to 3A and the Reference Example were measured. An absolute PL quantum yield measurement system C111347 manufactured by Hamamatsu Photonics KK was used for the measurements. These wavelength conversion layers were then baked in air at 150°C for 500 hours. Thereafter, the emission characteristics were measured again.

[0118] The results are shown in Table 1. In Table 1, the mass ratio of the inorganic phosphor to the mass of the total solid content of the photosensitive resin composition is shown as the "amount of inorganic phosphor." Table 1 also shows the resin components contained in the photosensitive resin composition.

[0119] [Table 1]

[0120] As shown in Table 1, the wavelength conversion layer of Example 1A had an initial (before baking) photoluminescence quantum yield (PLQY) comparable to that of the wavelength conversion layer of the Reference Example, both when excitation light with a wavelength of 450 nm was used and when excitation light with a wavelength of 385 nm was used. Similarly to the wavelength conversion layer of the Reference Example, the wavelength conversion layer of Example 1A showed almost no decrease in photoluminescence quantum yield (PLQY) due to heating (baking), both when excitation light with a wavelength of 450 nm was used and when excitation light with a wavelength of 385 nm was used.

[0121] The wavelength conversion layers of Examples 2A and 3A had high initial (before baking) photoluminescence quantum yields (PLQY) both when excitation light with a wavelength of 450 nm was used and when excitation light with a wavelength of 385 nm was used, although not as high as the wavelength conversion layer of Example 1 A. Furthermore, the wavelength conversion layers of Examples 2A and 3A showed a significant decrease in photoluminescence quantum yield (PLQY) due to heating (baking) when excitation light with a wavelength of 385 nm was used, but the decrease was not as large as when excitation light with a wavelength of 450 nm was used.

[0122] (2) Test B (2.1) Formation of wavelength conversion layer (2.1.1) Example 1B A photosensitive resin composition was obtained in the same manner as in Example 1A, except for the following points: In this example, (Ba, Sr, Ca, Mg) was used as the inorganic phosphor. 10 It contains crystals represented by (PO4)6Cl2:Eu, and the volume-based median diameter D 50 A blue phosphor with a particle size of 5.3 μm was used. The dispersant used was BYK (registered trademark)-311 (manufactured by BYK-Chemie; modified silicone-based dispersant CK), an aromatic modified silicone-based dispersant. The total solid content of the photosensitive resin composition was 56.2 mass%. The amount of the inorganic phosphor was 53.4 mass parts per 100 mass parts of the total solid content. The amount of the photopolymerizable compound A was 35.5 mass parts, the amount of the photopolymerization initiator A was 3.8 mass parts, the amount of the acrylic resin A was 47.3 mass parts, and the amount of the modified silicone-based dispersant CK was 13.4 mass parts per 100 mass parts of the total solid content excluding the inorganic phosphor.

[0123] Next, the photosensitive resin composition was applied to a glass substrate by spin coating to form a photosensitive layer, which was then left to stand for 30 minutes, dried in a vacuum dryer, and then pre-baked at 100°C for 3 minutes.

[0124] Next, the entire surface of the photosensitive layer was exposed to ihg rays at an exposure dose of 200 mJ / cm2 The photosensitive layer was then subjected to shower development using an aqueous sodium hydroxide solution, followed by baking in air at 230°C for 20 minutes to obtain a wavelength conversion layer having a thickness of approximately 20 μm.

[0125] (2.1.2) Example 2B A photosensitive resin composition was obtained in the same manner as in Example 1B, except for the following points: In this example, the total solid content of the photosensitive resin composition was 66.2 mass %, and the amount of inorganic phosphor was 60.4 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0126] (2.1.3) Example 3B A photosensitive resin composition was obtained in the same manner as in Example 1B, except for the following points: In this example, modified silicone-based dispersant CL was used as the modified silicone-based dispersant.

[0127] (2.1.4) Example 4B A photosensitive resin composition was obtained in the same manner as in Example 3B, except for the following points: In this example, the total solid content of the photosensitive resin composition was 66.2 mass %, and the amount of inorganic phosphor was 60.4 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0128] (2.1.5) Example 5B A photosensitive resin composition was obtained in the same manner as in Example 1B, except for the following points: In this example, a polyether-modified silicone-based dispersant, BYK (registered trademark)-320 (modified silicone-based dispersant CQ) manufactured by BYK-Chemie, was used as the modified silicone-based dispersant.

[0129] (2.1.6) Example 6B A photosensitive resin composition was obtained in the same manner as in Example 5B, except for the following points: In this example, the total solid content of the photosensitive resin composition was 66.2 mass %, and the amount of inorganic phosphor was 60.4 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0130] (2.1.7) Comparative example 1B A wavelength conversion layer was formed in the same manner as in Example 1B, except that the following photosensitive resin composition was used: In this example, polyacrylic acid (Aron (registered trademark) T-50, manufactured by Toagosei Co., Ltd.) was used as the dispersant.

[0131] (2.1.8) Comparative Example 2B A photosensitive resin composition was obtained in the same manner as in Comparative Example 1B, except for the following points: In this example, the total solid content of the photosensitive resin composition was 66.2 mass %, and the amount of inorganic phosphor was 60.4 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0132] (2.2) Evaluation The wavelength-converting layers of Examples 1B to 6B and Comparative Examples 1B and 2B were observed under a microscope. The wavelength-converting layers of Examples 1B to 4B had uniform thicknesses and flat surfaces. In contrast, the wavelength-converting layers of Examples 5B and 6B had uniform thicknesses but had surface irregularities due to particles. The wavelength-converting layers of Comparative Examples 1B and 2B had non-uniform thicknesses.

[0133] Next, the emission characteristics of the wavelength conversion layers according to Examples 1B to 6B were measured using an absolute PL quantum yield measurement system C111347 manufactured by Hamamatsu Photonics KK Light with a wavelength of 385 nm was used as excitation light.

[0134] The results are shown in Table 2. In Table 2, the mass ratio of the inorganic phosphor to the mass of the total solid content of the photosensitive resin composition is shown as the "amount of inorganic phosphor," and the resin components contained in the photosensitive resin composition are also shown.

[0135] [Table 2]

[0136] In Table 2, with regard to the luminescence characteristics of Examples 3B and 5B, the column labeled "Difference from Example 1B or Example 2B" lists the difference in luminescence characteristics from Example 1B. Also, in Table 2, with regard to the luminescence characteristics of Examples 4B and 6B, the column labeled "Difference from Example 1B or Example 2B" lists the difference in luminescence characteristics from Example 2B.

[0137] As shown in Table 2, the wavelength-converting layers of Examples 3B and 5B had higher photoluminescence quantum yields (PLQY) than the wavelength-converting layer of Example 1B. Also, as shown in Table 2, the wavelength-converting layers of Examples 4B and 6B had higher photoluminescence quantum yields (PLQY) than the wavelength-converting layer of Example 2B.

[0138] (3) Test C (3.1) Formation of wavelength conversion layer (3.1.1) Example 1C A photosensitive resin composition was obtained in the same manner as in Example 1A, except for the following points: In this example, (Ba, Sr, Ca, Mg) was used as the inorganic phosphor. 10 It contains crystals represented by (PO4)6Cl2:Eu, and the volume-based median diameter D 50 A blue phosphor with a particle size of 5.4 μm was used. Furthermore, a modified silicone-based dispersant CK was used as the dispersant. The photosensitive resin composition further contained ACEMATT (registered trademark), silica particles manufactured by Evonik, as a thickener. The total solid content of the photosensitive resin composition was 63.2% by mass. The amount of the inorganic phosphor was 47.5 parts by mass per 100 parts by mass of the total solid content. The amount of the photopolymerizable compound was 28.0 parts by mass, the amount of the photopolymerization initiator was 3.0 parts by mass, the amount of the acrylic resin was 37.3 parts by mass, the amount of the modified silicone-based dispersant was 21.1 parts by mass, and the amount of the thickener was 10.5 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0139] Next, the photosensitive resin composition was applied to a glass substrate by spin coating to form a photosensitive layer, which was then left to stand for 30 minutes, dried in a vacuum dryer, and then pre-baked at 100°C for 3 minutes.

[0140] Next, the entire surface of the photosensitive layer was exposed to ihg rays at an exposure dose of 200 mJ / cm 2 The photosensitive layer was then subjected to shower development using an aqueous sodium hydroxide solution, followed by baking in air at 230°C for 20 minutes to obtain a wavelength conversion layer with a thickness of approximately 15 μm.

[0141] (3.1.2) Example 2C A photosensitive resin composition was obtained in the same manner as in Example 1C, except for the following points: In this example, the total solid content of the photosensitive resin composition was 73.2 mass %, and the amount of inorganic phosphor was 54.6 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0142] (3.1.3) Example 3C A photosensitive resin composition was obtained in the same manner as in Example 1C, except for the following points: In this example, (Ba, Sr, Ca, Mg) was used as the inorganic phosphor. 10 It contains crystals represented by (PO4)6Cl2:Eu, and the volume-based median diameter D 50 A blue phosphor with a particle size of 4.9 μm was used, and dispersant CL was used as a modified silicone-based dispersant. The total solid content of the photosensitive resin composition was 57.2% by mass. Furthermore, the amount of inorganic phosphor was 52.4 parts by mass per 100 parts by mass of the total solid content of the photosensitive resin composition. The amount of photopolymerizable compound was 34.2 parts by mass, the amount of photopolymerization initiator was 3.7 parts by mass, the amount of acrylic resin was 45.6 parts by mass, the amount of modified silicone-based dispersant was 12.9 parts by mass, and the amount of thickener was 3.7 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0143] (3.1.4) Example 4C A photosensitive resin composition was obtained in the same manner as in Example 3C, except for the following points: In this example, the total solid content of the photosensitive resin composition was 67.2 mass %, and the amount of inorganic phosphor was 59.5 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0144] (3.1.5) Example 5C A photosensitive resin composition was obtained in the same manner as in Example 1C, except for the following points: In this example, (Ba, Sr, Ca, Mg) was used as the inorganic phosphor. 10 It contains crystals represented by (PO4)6Cl2:Eu, and the volume-based median diameter D 50 A blue phosphor with a particle size of 4.9 μm was used, and dispersant CQ was used as a modified silicone-based dispersant. The total solid content of the photosensitive resin composition was 57.2% by mass. Furthermore, the amount of inorganic phosphor was 52.4 parts by mass per 100 parts by mass of the total solid content of the photosensitive resin composition. The amount of photopolymerizable compound was 34.2 parts by mass, the amount of photopolymerization initiator was 3.7 parts by mass, the amount of acrylic resin was 45.6 parts by mass, the amount of modified silicone-based dispersant was 12.9 parts by mass, and the amount of thickener was 3.7 parts by mass per 100 parts by mass of the total solid content excluding the inorganic phosphor.

[0145] (3.1.6) Example 6C A photosensitive resin composition was obtained in the same manner as in Example 5C, except for the following points: In this example, the total solid content of the photosensitive resin composition was 67.2 mass %, and the amount of inorganic phosphor was 59.5 mass parts per 100 mass parts of the total solid content of the photosensitive resin composition.

[0146] (3.2) Evaluation The wavelength-converting layers of Examples 1C to 6C were observed under a microscope. As a result, the wavelength-converting layers of Examples 1C, 2C, 5C, and 6C had uniform thicknesses and flat surfaces. In contrast, the wavelength-converting layers of Examples 3C and 4C had uniform thicknesses but had surface irregularities due to particles.

[0147] Next, the light emission characteristics of the wavelength conversion layers according to Examples 1C to 6C were measured using an absolute PL quantum yield measurement system C111347 manufactured by Hamamatsu Photonics KK Light with a wavelength of 385 nm was used as excitation light.

[0148] The results are shown in Table 3. In Table 3, the mass ratio of the inorganic phosphor to the mass of the total solid content of the photosensitive resin composition is shown as the "amount of inorganic phosphor," and the resin components contained in the photosensitive resin composition are also shown.

[0149] [Table 3]

[0150] In Table 3, with regard to the luminescence characteristics of Examples 3C and 5C, the column labeled "Difference from Example 1C or Example 2C" lists the difference in luminescence characteristics from Example 1C. Also, in Table 3, with regard to the luminescence characteristics of Examples 4C and 6C, the column labeled "Difference from Example 1C or Example 2C" lists the difference in luminescence characteristics from Example 2C.

[0151] As shown in Table 3, the wavelength conversion layers of Examples 3C and 4C had photoluminescence quantum yields (PLQY) equivalent to those of Examples 1C and 2C, respectively. Also, as shown in Table 3, the wavelength conversion layers of Examples 5C and 6C had photoluminescence quantum yields (PLQY) smaller than those of Examples 1C and 2C, but still sufficiently large.

[0152] Next, the wavelength conversion layers according to Examples 2C, 4C, and 6C were baked in air at 150° C. for 500 hours, after which the luminescence properties were measured again.

[0153] The results are shown in Table 4. In Table 4, the mass ratio of the inorganic phosphor to the mass of the total solid content of the photosensitive resin composition is shown as the "amount of inorganic phosphor," and the resin components contained in the photosensitive resin composition are also shown.

[0154] [Table 4]

[0155] As shown in Table 4, the wavelength conversion layers according to Examples 2C, 4C, and 6C showed almost no decrease in photoluminescence quantum yield (PLQY) due to heating (baking). [Explanation of symbols]

[0156] 1...display device, 2...dimming device, 3...wavelength conversion substrate, 4...adhesive layer, 21...substrate, 22...multilayer wiring layer, 23...light-emitting diode, 31...transparent substrate, 32...black matrix, 33...partition wall layer, 33B...underlying layer, 33G...second colored layer, 33R...first colored layer, 34...partition wall layer, 36B...filling layer, 36G...second wavelength conversion layer, 36R...first wavelength conversion layer.

Claims

1. A photosensitive resin composition comprising: a photosensitive resin containing a photopolymerizable compound, a photopolymerization initiator, an acrylic resin, a modified silicone dispersant, and an organic solvent; and an inorganic phosphor that emits red, green, or blue fluorescence and is dispersed in the photosensitive resin.

2. 2. The photosensitive resin composition according to claim 1, wherein the modified silicone-based dispersant is an aliphatic modified silicone.

3. 2. The photosensitive resin composition according to claim 1, wherein the acrylic resin is a copolymer containing a structural unit having an N-(cyclohexyl)succinimide skeleton and a structural unit having a glutaric anhydride skeleton.

4. 2. The photosensitive resin composition according to claim 1, wherein the photopolymerizable compound contains a tri- or higher functional (meth)acrylate compound.

5. 2. The photosensitive resin composition according to claim 1, comprising, relative to 100 parts by mass of a total solid content, the inorganic phosphor in an amount of 10 to 80 parts by mass, the photopolymerizable compound in an amount of 1 to 80 parts by mass, the photopolymerization initiator in an amount of 0.1 to 10 parts by mass, the acrylic resin in an amount of 5 to 60 parts by mass, and the modified silicone dispersant in an amount of 1 to 50 parts by mass, relative to 100 parts by mass of a total solid content excluding the inorganic phosphor.

6. A wavelength conversion layer comprising a cured product of the photosensitive resin composition according to claim 1 .

7. An article comprising the wavelength converting layer of claim 6.

8. 8. The article of claim 7, which is a wavelength conversion substrate.

9. 8. The article of claim 7 which is a display device.

10. 2. A phosphor dispersion liquid used in preparing the photosensitive resin composition according to claim 1, the phosphor dispersion liquid comprising an inorganic phosphor that emits red, green, or blue fluorescence, a modified silicone-based dispersant, and an organic solvent.

11. The phosphor dispersion liquid according to claim 10, wherein the modified silicone-based dispersant is an aliphatic modified silicone.

12. The phosphor dispersion liquid according to claim 10 , further comprising an acrylic resin.

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