Inkjet ink for partition wall formation and LED devices

Abstract

A problem of the present invention is to provide: an inkjet ink for forming a partition and an inkjet ink set for forming a partition, with which a partition that can improve high-temperature durability of an LED device can be formed between LED chips; a method for manufacturing an LED device using said inkjet ink set; and an LED device in which high-temperature durability is improved.　This inkjet ink for forming a partition is for forming a partition between LED chips of an LED device, and is characterized by comprising a photopolymerizable composition, a coloring material, and a gelling agent, and by undergoing a sol-gel phase transition depending on temperature.

Description

[Technical Field]

[0001] The present invention relates to an ink-jet ink for forming partition walls. , and and LED devices. More particularly, the present invention relates to an inkjet ink for forming partition walls, which can form partition walls between LED chips and can improve the high-temperature durability of LED devices. [Background technology]

[0002] In LED devices such as LED (light emitting diode) displays, a technique for providing a partition between adjacent LED chips is used to prevent color mixing between the LED chips. Conventional methods for forming such partitions include photolithography, coating, and screen printing. However, photolithography can cause problems with damage to the LED chips due to the developer. Furthermore, coating methods are inefficient, and screen printing methods are difficult to achieve with fine processing.

[0003] As a technique that can solve these problems, for example, Patent Documents 1 and 2 disclose a technique for forming partition walls by an inkjet method. In forming partition walls by the inkjet method, the partition walls can be formed without contacting the LED chips, so there is no damage to the LED chips, and the partition walls can be formed more efficiently than by coating methods, and further, fine processing is also possible.

[0004] On the other hand, LED devices are required to have durability to withstand long-term use, particularly durability in high-temperature environments. LED devices in which partition walls are formed using the inks disclosed in Patent Documents 1 and 2 do not have sufficient high-temperature durability, so there has been a demand for an ink for forming partition walls by an inkjet method that can also improve the high-temperature durability of LED devices. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-210438 [Patent Document 2] Patent Publication No. 2021-046528 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide an inkjet ink for forming a partition wall, which can form a partition wall between LED chips and can improve the high-temperature durability of the LED device, an inkjet ink set for forming a partition wall, a method for manufacturing an LED device using the same, and an LED device with improved high-temperature durability. [Means for solving the problem]

[0007] In order to solve the above problems, the present inventors have investigated the causes of the above problems and have found that by incorporating a photopolymerizable composition, a colorant, and a gelling agent to form an ink that undergoes a sol-gel phase transition depending on the temperature, it is possible to provide an inkjet ink for forming partition walls that can form partition walls between LED chips and that can improve the high-temperature durability of LED devices, thereby completing the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. An inkjet ink for forming partition walls for forming partition walls between LED chips of an LED device, comprising: A photopolymerizable composition (excluding a case where the composition contains a photopolymerizable compound having no acidic group and a photopolymerizable compound having an acidic group), a colorant, and a gelling agent, Sol-gel phase transition occurs due to temperature. The ink-jet ink for forming partition walls, characterized in that the color material contains a white color material or a black color material.

[0009] 2 The photopolymerizable composition contains a (meth)acrylate compound as a component. The first feature is In the section The inkjet ink for forming partition walls according to the present invention.

[0011] 3 Viscosity at 25°C is 1 to 1 x 10 4 Within the Pa·s range, and Sol-gel phase transition temperature in the range of 40°C to 100°C 3. The ink-jet ink for forming partition walls according to item 1 or 2.

[0012] 4 The gelling agent contains at least one compound selected from compounds having a structure represented by the following general formula (G1) or (G2): 3. The ink-jet ink for forming partition walls according to item 1 or 2. General formula (G1): R1-CO-R2 General formula (G2): R3-COO-R4 [In the formula, R1 to R4 each independently represent an alkyl chain having 12 or more carbon atoms and a linear portion, which may be branched.]

[0013] 5 The gelling agent is contained in the range of 0.5 to 5% by mass of the total ink. 3. The ink-jet ink for forming partition walls according to item 1 or 2.

[0019] 6 An LED device having a partition between LED chips, the partition wall contains a cured product of a photopolymerizable composition (excluding a case where the composition contains a photopolymerizable compound having no acidic group and a photopolymerizable compound having an acidic group), a colorant, and a gelling agent; The partition walls are composed of at least white partition walls or black partition walls. An LED device characterized by: [Effects of the Invention]

[0023] According to the above-mentioned means of the present invention, there is provided an ink-jet ink for forming partition walls, which can form partition walls between LED chips, which can improve the high-temperature durability of LED devices. and An LED device can be provided.

[0024] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0025] The inkjet ink for partition wall formation of the present invention is characterized by containing a gelling agent. By containing a gelling agent, the surface of the partition wall formed using the ink becomes rougher than when the ink does not contain a gelling agent. In LED devices, a transparent encapsulant is used to protect the LED chip, and the partition wall formed using the ink of the present invention has a rough surface, which increases the area of ​​the contact interface between the partition wall and the transparent encapsulant and improves adhesion. As a result, gaps are less likely to occur between the partition wall and the transparent encapsulant, improving sealing and the high-temperature durability of the LED device.

[0026] It is believed that due to these mechanisms of expression or action, the inkjet ink for forming partition walls of the present invention can form partition walls between LED chips that can improve the high-temperature durability of LED devices. [Brief explanation of the drawings]

[0027] [Figure 1A] FIG. 1A is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 1B] FIG. 1B is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 1C] FIG. 1C is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 2A]FIG. 2A is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 2B] FIG. 2B is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 2C] FIG. 2C is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 3A] 3A is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 3B] FIG. 3B is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 3C] FIG. 3C is a schematic cross-sectional view of a portion of an LED device illustrating the appearance of partition walls formed by the ink of the present invention. [Figure 4] Schematic diagram showing an LED device without barrier ribs [Figure 5] Schematic diagram showing the pattern in which partition walls are formed to surround each LED chip [Figure 6] Schematic diagram showing a pattern in which partition walls are formed to surround pixels made up of three-color LED chips [Figure 7] A schematic diagram showing a pattern in which partition walls are formed to surround each LED chip, but the partition walls are formed to a certain width, and there are also areas between pixels where no partition wall is formed. DETAILED DESCRIPTION OF THE INVENTION

[0028] The inkjet ink for partition formation of the present invention is an inkjet ink for partition formation used to form partitions between LED chips in an LED device, and is characterized by containing a photopolymerizable composition, a colorant, and a gelling agent, and undergoing a sol-gel phase transition depending on temperature. This feature is a technical feature common to or corresponding to the following embodiments.

[0029] In an embodiment of the inkjet ink for partition wall formation of the present invention, from the viewpoint of the polymerization rate, polymerization degree, etc., it is preferred that the photopolymerizable composition contains a (meth)acrylate compound.

[0030] In an embodiment of the inkjet ink for forming partition walls of the present invention, the color material preferably contains a white color material or a black color material, thereby making it possible to form white partition walls that can improve brightness or black partition walls that can improve contrast.

[0031] In an embodiment of the ink-jet ink for partition wall formation of the present invention, the viscosity at 25° C. is 1 to 1×10 4 A viscosity within the Pa·s range is preferred because it allows the ink to gel sufficiently when it lands and cools to room temperature, resulting in good pinning properties. It is also preferred that the sol-gel phase transition point is in the range of 40°C or higher but less than 100°C. If the sol-gel phase transition point is 40°C or higher, the ink will gel quickly after landing, resulting in better pinning properties. If the sol-gel phase transition point is less than 100°C, the ink will be easier to handle and have higher ejection stability.

[0032] In an embodiment of the inkjet ink for partition wall formation of the present invention, the gelling agent preferably contains at least one compound selected from compounds having a structure represented by the general formula (G1) or (G2) above. The compound having the structure represented by the general formula (G1) or the compound having the structure represented by the general formula (G2) has a linear or branched hydrocarbon group (alkyl chain) with 12 or more carbon atoms, which enhances the crystallinity of the gelling agent and creates more space in the house-of-card structure. This makes it easier for the ink medium, such as the polymerizable compound, to be fully enclosed within the space, thereby improving the pinning ability of the ink.

[0033] In an embodiment of the inkjet ink for partition wall formation of the present invention, the gelling agent is preferably contained in an amount of 0.5 to 5% by mass based on the total mass of the ink. By setting the content of the gelling agent within this range, the solubility and pinning effect of the gelling agent are improved.

[0034] The inkjet ink set for partition wall formation of the present invention is an inkjet ink set for forming partition walls between LED chips in an LED device, comprising a first inkjet ink for partition wall formation and a second inkjet ink for partition wall formation, wherein the first inkjet ink for partition wall formation contains a photopolymerizable composition, a white colorant, and a gelling agent, and undergoes a sol-gel phase transition depending on the temperature, and the second inkjet ink for partition wall formation contains a photopolymerizable composition, a black colorant, and a gelling agent, and also undergoes a sol-gel phase transition depending on the temperature.

[0035] The method for manufacturing an LED device of the present invention is a method for manufacturing an LED device having partitions between LED chips, and includes a partition formation step of patterning the partitions by an inkjet method, and is characterized in that the partition formation step uses an inkjet ink for forming partitions, which contains a photopolymerizable composition, a colorant, and a gelling agent, and which undergoes a sol-gel phase transition depending on temperature.

[0036] In an embodiment of the method for manufacturing an LED device of the present invention, the partition wall forming step preferably includes at least a white partition wall forming step, which makes it possible to form white partition walls capable of improving brightness.

[0037] In an embodiment of the method for manufacturing an LED device of the present invention, the partition wall forming step preferably includes at least a black partition wall forming step, which makes it possible to form black partition walls capable of improving contrast.

[0038] In an embodiment of the LED device manufacturing method of the present invention, the partition wall forming step preferably includes at least a white partition wall forming step and a black partition wall forming step of forming black partition walls on the white partition walls formed in the white partition wall forming step, thereby forming partition walls whose upper surfaces, which contribute to improving contrast, are black and whose side surfaces, which contribute to improving brightness, are partially white.

[0039] The LED device of the present invention is an LED device having partition walls between LED chips, characterized in that the partition walls contain a cured product of a photopolymerizable composition, a coloring material, and a gelling agent.

[0040] In an embodiment of the LED device of the present invention, the partition walls are preferably composed of at least white partition walls, which can improve brightness.

[0041] In an embodiment of the LED device of the present invention, the partition walls are preferably made of at least black partition walls, which can improve contrast.

[0042] In an embodiment of the LED device of the present invention, the partition walls preferably comprise at least a white partition wall and a black partition wall located thereon, thereby making it possible to simultaneously improve brightness and contrast by making the upper surface, which contributes to improving contrast, black and the side surface, which contributes to improving brightness, partially white.

[0043] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0044] <1. Inkjet ink for partition formation> The ink-jet ink for partition wall formation (hereinafter also simply referred to as "ink") of the present invention is an ink-jet ink for partition wall formation for forming partition walls between LED chips of an LED device, and is characterized by containing a photopolymerizable composition, a colorant, and a gelling agent, and undergoing a sol-gel phase transition depending on temperature.

[0045] <1.1 Ink applications> The ink of the present invention is an ink-jet ink for forming partition walls between LED chips in an LED device.

[0046] In the present invention, the term "partition wall" refers to a wall formed between adjacent pixels or LED chips in an LED device to prevent color mixing between adjacent LED chips, and having a height of 25% or more of the height of the LED chip.

[0047] 1A to 1C and 2A to 2C are schematic cross-sectional views of a portion of an LED device to illustrate the appearance of partition walls formed using the ink of the present invention. In an LED device 1 in which red LED chips 3R, green LED chips 3G, and blue LED chips 3B are arranged on a substrate 2, partition walls 4 (black partition walls 4Bl and white partition walls 4Wh) may be formed to cover the periphery of each LED chip, as shown in FIGS. 1A to 1C, or may be formed to cover the periphery of a pixel consisting of LED chips of three colors, as shown in FIGS. 1A to 1C and 2A to 1C. A transparent encapsulant 5 and a cover glass 6 for encapsulating the LED chips are also shown in FIGS. 1A to 1C and 2A to 1C.

[0048] The height of the partition wall relative to the height of the LED chip must be 25% or more, but to better prevent color mixing, it is preferably 50% or more, and more preferably 75% or more. Moreover, since if the partition wall is too high, the brightness will decrease, the height of the partition wall relative to the height of the LED chip is preferably 200% or less.

[0049] Figures 1A-C and Figures 2A-C show LED devices in which partition walls are formed with a height that is approximately 150% of the height of the LED chip, and Figures 3A-C show LED devices in which partition walls are formed with a height that is approximately 50% of the height of the LED chip.

[0050] Fig. 4 shows an LED device in which no partitions are formed, and Figs. 5 to 7 show LED devices in which partitions are formed in different patterns. Figs. 4 to 7 are all schematic top views of a part of the LED device, showing an area equivalent to four pixels, where one pixel is a set consisting of a red LED chip 3R, a green LED chip 3G, and a blue LED chip 3B.

[0051] Figure 5 corresponds to the state of Figures 1A to 1C and Figures 3A to 3C viewed from above (the transparent sealant 5 and cover glass 6 are not shown, and the number of LED chips is also different), and shows a pattern in which partition walls 4 are formed to cover the periphery of each LED chip.

[0052] Figure 6 corresponds to the state of Figures 2A to 2C viewed from above (the transparent sealant 5 and cover glass 6 are not shown), and shows a pattern in which partition walls 4 are formed to cover the periphery of pixels consisting of three-color LED chips.

[0053] Figure 7 shows a pattern in which, like Figure 5, partitions 4 are formed to surround each LED chip, but the partitions are formed to a certain width and there are also areas between pixels where no partitions are formed.

[0054] 1 to 7 illustrate embodiments, and do not limit the pattern of the partition walls formed by the ink of the present invention or the arrangement of LED chips in an LED device using the ink of the present invention.

[0055] The cross-sectional shape of the partition wall in the width direction may be a shape in which the widths of the lower and upper parts are approximately constant, or may be a tapered shape in which the width is wider at the lower part, or a reverse tapered shape in which the width is wider at the upper part. The width of the partition wall is not particularly limited.

[0056] The color of the partition wall is not particularly limited, but is preferably white from the viewpoint of reflecting light emitted by the LED chip and improving brightness. Furthermore, from the viewpoint of improving contrast, it is preferably black. FIGS. 1A and 2A show an LED device in which white partition walls 4Wh are formed, and FIGS. 1B and 2B show an LED device in which black partition walls 4Bl are formed. Furthermore, it is also preferable that the color of the partition wall be gray in order to control reflectance and contrast.

[0057] In the present invention, "white" refers to a color having a lightness of 8.0 or more and a saturation of 2.0 or less in the Munsell color system (JIS Z 8721). "Black" refers to a color having a lightness of 2.0 or less and a saturation of 2.0 or less in the Munsell color system (JIS Z 8721). "Gray" refers to a mixed color of white and black.

[0058] The partition walls formed by the ink of the present invention may be configured by stacking partition walls of two or more different colors. For example, as shown in Figures 1C, 2C, and 3C, by forming a partition wall 4 consisting of a white partition wall 4Wh and a black partition wall 4Bl located above it, the top surface, which contributes to improving contrast, can be made black, while the side surface, which contributes to improving brightness, can be made partially white, thereby simultaneously improving brightness and contrast. In the case of a partition wall configured by stacking partition walls of two or more different colors, the dimensions such as height and width described above refer to the dimensions of the entire partition wall.

[0059] The ink of the present invention is an ink used to form the above-mentioned partition walls.

[0060] <1.2 Ink components> The ink of the present invention is characterized by containing a photopolymerizable composition, a coloring material, and a gelling agent. The components will be described in detail below.

[0061] (Photopolymerizable composition) The photopolymerizable composition according to the present invention preferably contains at least a polymerizable compound as a component, and further contains a photopolymerization initiator as needed.

[0062] The content of the polymerizable compound is preferably within a range of 1 to 97% by mass, and more preferably within a range of 30 to 90% by mass, based on the total mass of the ink.

[0063] The polymerizable compound is not particularly limited, and can be a compound that initiates a polymerization reaction when irradiated with active energy rays (electron beams, ultraviolet rays, α rays, γ rays, X-rays, etc.) in the presence or absence of a photopolymerization initiator, and is cured by polymerization and crosslinking. The polymerizable compound may be any of a monomer, a polymerizable oligomer, a prepolymer, and a mixture thereof.

[0064] Examples of the polymerizable compound include a cationically polymerizable compound, a radically polymerizable compound, or a mixture thereof. From the viewpoints of the polymerization rate and degree of polymerization, a radically polymerizable compound is preferred, and a (meth)acrylate compound is more preferred.

[0065] The term "radical polymerizable compound" refers to a compound having an ethylenically unsaturated double bond in the molecule. The radical polymerizable compound may be either a monofunctional or polyfunctional compound.

[0066] The radical polymerizable compound may be a (meth)acrylate compound, which is an unsaturated carboxylic acid ester compound. In the present invention, "(meth)acrylate" refers to acrylate or methacrylate. In the present invention, "(meth)acrylate compound" includes a compound containing a (meth)acryloyl group in the main chain, a compound having a (meth)acryloyl group as a side chain, and a compound having a (meth)acryloyl group as a substituent on the side chain.

[0067] Examples of (meth)acrylate compounds having no acidic group include isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomylstyryl (meth)acrylate, isostearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, phenoxy Monofunctional acrylates including diethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, and t-butylcyclohexyl (meth)acrylate, as well as triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,Examples of the acrylate include bifunctional acrylates such as 9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, and tricyclodecane dimethanol diacrylate, as well as multifunctional acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, and pentaerythritol ethoxy tetra(meth)acrylate.

[0068] Examples of (meth)acrylate compounds having a carboxy group include (meth)acrylate compounds having a hydroxy group and (meth)acrylates obtained by adding an acid anhydride to an oligomer of these compounds. Examples of the acid anhydride include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, himic anhydride, maleic anhydride, trimellitic anhydride, methylcyclohexene tricarboxylic anhydride, and pyromellitic anhydride. Specific examples of the (meth)acrylate compound having a carboxy group include (meth)acryloyloxyalkoxycarbonylphthalates such as 2-carboxyethyl acrylate, 4-(meth)acryloyloxyethoxycarbonylphthalic acid, 4-(meth)acryloyloxybutoxycarbonylphthalic acid, 4-(meth)acryloyloxyhexyloxycarbonylphthalic acid, and 4-(meth)acryloyloxydecyloxycarbonylphthalic acid; Examples of the acryloyloxyalkyl phthalates include (meth)acryloyloxyalkoxyalkoxycarbonylphthalic acids such as diethoxyethoxycarbonylphthalic acid, mono-2-(acryloyloxy)ethyl succinate, 2,2-bis(acryloylamido)acetic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl-2-hydroxyethyl-phthalic acid, and 2-(meth)acryloyloxyethylhexahydrophthalic acid.

[0069] Examples of the (meth)acrylate compound having a phosphoric acid group include bis(2-(meth)acryloyloxyethyl)phosphate ester, 2-hydroxyethyl (meth)acrylate acid phosphate, ethyl (meth)acrylate acid phosphate, 3-chloro-2-acidphosphooxypropyl (meth)acrylate, polyoxyethylene glycol (meth)acrylate acid phosphate, 2-(meth)acryloyloxyethyl caproate acid phosphate, and mono-2-(methacryloyloxy)ethyl phosphate. Furthermore, 2-(meth)acryloyloxyethyl phosphate (meaning 2-acryloyloxyethyl phosphate or 2-methacryloyloxyethyl phosphate, hereinafter this abbreviation will be used), 2-(meth)acryloyloxypropyl phosphate, 3-(meth)acryloyloxypropyl phosphate, 4-(meth)acryloyloxybutyl phosphate, 6-(meth)acryloyloxyhexyl phosphate, 8-(meth)acryloyloxyoctyl phosphate, 10-(meth)acryloyloxydecyl phosphate, 12-(meth)acryloyloxylauryl phosphate, 16-(meth)acryloyloxycetyl phosphate, 18-(meth)acryloyloxyethyl phosphate, 19-(meth)acryloyloxyethyl phosphate, 20-(meth)acryloyloxyethyl phosphate, 21-(meth)acryloyloxyethyl phosphate, 22-(meth)acryloyloxyethyl phosphate, 23-(meth)acryloyloxyethyl phosphate, 24-(meth)acryloyloxyethyl phosphate, 25-(meth)acryloyloxyethyl phosphate, 26-(meth)acryloyloxyethyl phosphate, 27-(meth)acryloyloxyethyl phosphate, 28-(meth)acryloyloxyethyl phosphate, 29-(meth)acryloyloxyethyl phosphate, 30-(meth)acryloyloxyethyl phosphate, 31-(meth)acryloyloxyethyl phosphate, 32-(meth)acryloyloxyethyl phosphate, 33-(meth)acryloyloxyethyl phosphate, 34-(meth)acryloyloxyethyl phosphate, 35-(meth)acryloyloxyethyl phosphate, 36-(meth)acryloyloxyethyl phosphate, 37-(meth)acryloyloxyethyl phosphate, 38-( (meth)acryloyloxyalkyl phosphate esters such as 20-(meth)acryloyloxyeicosyl phosphate ester; di(meth)acryloyloxyalkyl phosphate esters such as 1,3-di(meth)acryloyloxypropyl-2-phosphate ester; (meth)acryloyloxyalkylaryl phosphate esters such as 2-(meth)acryloyloxyethylphenyl phosphate ester, 2-(meth)acryloyloxyethylanisyl phosphate ester, and 2-(meth)acryloyloxyethyltolyl phosphate ester; (meth)acryloyloxyalkylaryl phosphonic acids such as 2-(meth)acryloyloxyethylphenylphosphonic acid;2-(meth)acryloyloxyethyl thiophosphate, 2-(meth)acryloyloxypropyl thiophosphate, 3-(meth)acryloyloxypropyl thiophosphate, 4-(meth)acryloyloxybutyl thiophosphate, 6-(meth)acryloyloxyhexyl thiophosphate, 8-(meth)acryloyloxyoctyl thiophosphate, 10-(meth)acryloyloxydecyl thiophosphate, 12-(meth)acryloyloxylauryl thiophosphate, 16-(meth)acryloyloxycetyl thiophosphate, 18-(meth)acryloyloxystearyl thiophosphate, 20-(meth)acryloyloxyeico Examples of such thiophosphates include (meth)acryloyloxyalkyl thiophosphates such as 2-(meth)acryloyloxypropyl-2-thiophosphate; di(meth)acryloyloxyalkyl thiophosphates such as 1,3-di(meth)acryloyloxypropyl-2-thiophosphate; (meth)acryloyloxyalkylaryl thiophosphates such as 2-(meth)acryloyloxyethyl phenyl thiophosphate, 2-(meth)acryloyloxyethyl anisyl thiophosphate, and 2-(meth)acryloyloxyethyl tolyl thiophosphate; and (meth)acryloyloxyalkylaryl thiophosphonic acids such as 2-(meth)acryloyloxyethyl phenyl thiophosphonic acid.

[0070] Examples of the (meth)acrylate compound having a sulfonic acid group include methallylsulfonic acid, bis(3-sulfopropyl)itaconic acid, 2-(sulfoxy)ethyl methacrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, 3-sulfopropylacrylic acid, 3-sulfopropylmethacrylic acid, and acrylamido-2-methyl-2-propanesulfonic acid.

[0071] Examples of the (meth)acrylate compound having a monofunctional hydroxy group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxymethylcyclohexylmethyl (meth)acrylate, and p-hydroxymethylphenylmethyl (meth)acrylate. , 2-(hydroxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxy)ethyl (meth)acrylate, methyl α-hydroxymethylacrylate, ethyl α-hydroxymethylacrylate, hydroxyalkyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate.

[0072] Examples of the (meth)acrylate compound having a polyfunctional hydroxy group include 2-hydroxy-3-acryloyloxypropyl methacrylate, dipentaerythritol penta(meth)acrylate, ethylene oxide-added pentaerythritol tetra(meth)acrylate, trimethylolpropane diacrylate, glycerin di(meth)acrylate, glycerin acrylate methacrylate, pentaerythritol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid dipentaerythritol tri(meth)acrylate, hydroxypivalaldehyde-modified dimethylolpropane tri(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, sorbitol hexa(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0073] The (meth)acrylate may be a modified product. Examples of modified (meth)acrylates include ethylene oxide-modified (meth)acrylates including ethylene oxide-modified trimethylolpropane tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetraacrylate, caprolactone-modified (meth)acrylates including caprolactone-modified trimethylolpropane tri(meth)acrylate, and caprolactam-modified (meth)acrylates including caprolactam-modified dipentaerythritol hexa(meth)acrylate.

[0074] The (meth)acrylate may be a polymerizable oligomer. Examples of the (meth)acrylate that is a polymerizable oligomer include an epoxy (meth)acrylate oligomer, an aliphatic urethane (meth)acrylate oligomer, an aromatic urethane (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, and a linear (meth)acrylic oligomer.

[0075] The term "cationically polymerizable compound" refers to a compound having a cationically polymerizable group in the molecule. Examples of the cationically polymerizable compound include epoxy compounds, vinyl ether compounds, and oxetane compounds.

[0076] Examples of the epoxy compound include alicyclic epoxy compounds (3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene monoepoxide, ε-caprolactone-modified 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexanecarboxylate, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4,1,0]heptane, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexanone-meta-dioxane, and bis(2,3-epoxycyclopentyl)ether, etc.), aliphatic epoxy compounds (diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerin, etc.), and the like. bisphenol A, triglycidyl ether of trimethylolpropane, diglycidyl ether of polyethylene glycol, diglycidyl ether of propylene glycol, polyglycidyl ether of polyether polyol, etc.), and aromatic epoxy compounds (diglycidyl ether of bisphenol A, diglycidyl ether of an alkylene oxide adduct of bisphenol A, diglycidyl ether of hydrogenated bisphenol A, diglycidyl ether of an alkylene oxide adduct of hydrogenated bisphenol A, polyglycidyl ether of bisphenol A, polyglycidyl ether of an alkylene oxide adduct of bisphenol A, polyglycidyl ether of hydrogenated bisphenol A, polyglycidyl ether of an alkylene oxide adduct of hydrogenated bisphenol A, and novolac-type epoxy resins, etc.).

[0077] Examples of vinyl ether compounds include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, octadecyl vinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether.

[0078] Examples of the oxetane compound include 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-n-butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, and 3-hydroxyethyl 3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyloxetane, 3-hydroxybutyl-3-methyloxetane, 1,4 bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and di[1-ethyl(3-oxetanyl)]methyl ether.

[0079] The photopolymerizable composition according to the present invention preferably contains a photopolymerization initiator as needed.

[0080] The content of the photopolymerization initiator can be set arbitrarily as long as the ink is sufficiently cured by irradiation with active energy rays and the ink jet ejection stability of the ink is not reduced. For example, the content of the photopolymerization initiator is preferably in the range of 0.1 to 20% by mass, and more preferably in the range of 1.0 to 12% by mass, of the total ink.

[0081] The photopolymerization initiator may be any photopolymerization initiator capable of initiating polymerization of the polymerizable compound. For example, when the ink contains a radically polymerizable compound, the photopolymerization initiator is a radical-based photopolymerization initiator, and when the ink contains a cationic polymerizable compound, the photopolymerization initiator is a cationic-based photopolymerization initiator.

[0082] The photopolymerization initiator may be used alone or in combination of two or more kinds. Also, both a radical photopolymerization initiator and a cationic photopolymerization initiator may be used in combination.

[0083] Radical photopolymerization initiators include intramolecular bond cleavage type and intramolecular hydrogen abstraction type.

[0084] Examples of the intramolecular bond cleavage type radical photopolymerization initiator include acetophenone-based photopolymerization initiators (diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-methylthiophenyl)propan-1-one, and 2-benzyl-2-dimethyl benzoin-based photopolymerization initiators (benzoin, benzoin methyl ether, benzoin isopropyl ether, etc.), acylphosphine oxide-based photopolymerization initiators (2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, etc.), benzyl and methylphenyl glyoxyesters, etc.

[0085] Among these, acylphosphine oxide-based photopolymerization initiators are preferred from the viewpoint of further improving the curability of the polymerizable compound, particularly the curability in a curing process using UV-LED light.

[0086] Commercially available acylphosphine oxide photopolymerization initiators include, for example, IRGACURE (registered trademark) 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide), IRGACURE (registered trademark) 1800 (a mixture of bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl-phenyl ketone in a mass ratio of 25:75), and IRGACURE (registered trademark) TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide).

[0087] Examples of intramolecular hydrogen abstraction type radical photopolymerization initiators include benzophenone-based photopolymerization initiators (benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methanone). thioxanthone-based photopolymerization initiators (2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, etc.), aminobenzophenone-based photopolymerization initiators (Michler's ketone, 4,4'-diethylaminobenzophenone, etc.), 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, camphorquinone, etc.

[0088] Examples of cationic photopolymerization initiators include photoacid generators, such as aromatic onium compounds B(C6F5)4, including diazonium, ammonium, iodonium, sulfonium, and phosphonium. - , PF6 - , AsF6 - , SbF6 - , CF3SO3 - These include salts, sulfonates that generate sulfonic acid, halides that photogenerate hydrogen halide, and iron-allene complexes.

[0089] (colorant) The ink of the present invention is characterized by containing a coloring material, which may be a pigment or a dye.

[0090] The color of the colorant is not particularly limited, and a colorant corresponding to the color of the partition walls to be formed may be used. The color of the partition walls is preferably white to improve the reflectance and brightness, and black to improve the contrast. Therefore, the color of the colorant is preferably white or black. The black colorant may be a single black colorant, or may be a mixture of red, green, blue, and other colorants. Furthermore, the color of the partition walls is preferably gray to control the reflectance and contrast. Therefore, it is also preferable to use a gray colorant as the colorant to be contained in the ink. The gray colorant can be prepared, for example, by mixing a white colorant and a black colorant.

[0091] The content of the coloring material is not particularly limited, but for white coloring materials, it is preferably in the range of 2 to 30% by mass, more preferably 5 to 20% by mass, and even more preferably 6 to 15% by mass, relative to the total mass of the ink. For black coloring materials, it is preferably in the range of 1 to 20% by mass, more preferably 1.5 to 15% by mass, and even more preferably 2 to 10% by mass, relative to the total mass of the ink.

[0092] Pigments that are preferably used as coloring materials contained in the ink of the present invention will be specifically described below.

[0093] Examples of white pigments include calcium carbonate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, antimony oxide, zirconium oxide, white hollow resin particles, polymer particles, etc. Among the above white pigments, titanium oxide and zirconium oxide are preferred, and titanium oxide is more preferred.

[0094] Examples of commercially available titanium oxides that can be used in the present invention include CR-EL, CR-50, CR-80, CR-90, R-780, R-930 (all manufactured by Ishihara Sangyo Kaisha), TCR-52, R-25, R-32, R-310 (all manufactured by Sakai Chemical Industry Co., Ltd.), KR-310, KR-380, and KR-380N (all manufactured by Titanium Industries Co., Ltd.), etc.

[0095] Examples of zirconium oxide that can be used as the white pigment include the commercially available product Zirconeo (manufactured by ITEC Co., Ltd., "Zirconeo" is a registered trademark of the company).

[0096] Examples of black pigments include pigments selected from Pigment Black 7, 28, and 26, or mixtures thereof.

[0097] Examples of commercially available black pigments include Black Pigment (manufactured by Mikuni Corporation), Chromofine Black A-1103 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), Colortex Black 702, U905 (manufactured by Sanyo Dishwashing Co., Ltd.), carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, and CF9 (all manufactured by Mitsubishi Chemical Corporation).

[0098] Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, and Pigment Orange. 13, 16, 20, and 36, or a mixture thereof.

[0099] Examples of blue or cyan pigments include pigments selected from Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, and 60, or mixtures thereof.

[0100] Examples of green pigments include pigments selected from Pigment Green 7, 26, 36, and 50, or mixtures thereof.

[0101] Examples of yellow pigments include pigments selected from Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, and 193, or mixtures thereof.

[0102] In addition to the pigments listed above, commercially available examples of pigments include Cromofine Yellow 2080, 5900, 5930, AF-1300, 2700L, Cromofine Orange 3700L, 6730, Cromofine Scarlet 6750, Cromofine Magenta 6880, 6886, 6891N, 6790, 6887, and Cromofine Violet. RE, Cromofine Red 6820, 6830, Cromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Cromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770, Seika Fast Yellow 8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B 1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B 800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.); KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (manufactured by DIC);Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow1705, Colortex Orange 202, Colortex Red101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Violet600, Pigment Red 122, Colortex Blue516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403; Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink Co., Ltd.), Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostapearm Blue B2G (manufactured by Hoechst Industrie); Novoperm P-HG, and Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant).

[0103] The pigment can be dispersed using, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, or the like.

[0104] When a pigment is used as the coloring material, from the viewpoint of improving ejection properties from an inkjet head, the average dispersed particle diameter of the pigment particles is preferably within a range of 50 to 150 nm, and the maximum particle diameter is preferably within a range of 300 to 1000 nm, and more preferably within a range of 80 to 130 nm.

[0105] The average dispersed particle size of pigment particles refers to the value determined by dynamic light scattering using a Datasizer Nano ZSP (Malvern). Note that inks containing colorants are highly concentrated, and light does not pass through this measuring device, so the ink is diluted 200 times before measurement. The measurement temperature is room temperature (25°C).

[0106] The dispersion of the pigment is adjusted by adjusting the pigment, dispersant, dispersion medium, dispersion conditions, filtration conditions, and the like.

[0107] When a pigment is used as the colorant, the ink of the present invention may further contain a dispersant to improve the dispersibility of the pigment. Examples of dispersants include carboxylic acid esters having a hydroxy group, salts of long-chain polyaminoamides and high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high-molecular-weight unsaturated acid esters, polymer copolymers, modified polyurethanes, modified polyacrylates, polyether ester-type anionic surfactants, naphthalene sulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, and stearylamine acetate. Examples of commercially available dispersants include the Solsperse series from Avecia and the PB series from Ajinomoto Fine-Techno Co., Ltd.

[0108] When a pigment is used as the coloring material, the ink of the present invention may contain a dispersing aid as needed. The dispersing aid may be selected depending on the pigment.

[0109] The total amount of the dispersant and dispersion aid is preferably within the range of 1 to 50% by mass relative to the pigment.

[0110] When a pigment is used as the colorant, the ink of the present invention may contain a dispersion medium for dispersing the pigment, if necessary. The dispersion medium may be a solvent, but in order to prevent damage to the LED chip, it is preferable to use a polymerizable compound (especially a monomer with low viscosity) as described above as the dispersion medium.

[0111] (gelling agent) By containing a gelling agent, the ink of the present invention can improve the adhesion between the partition walls and the transparent sealant, and can improve the high-temperature durability of the LED device.

[0112] Furthermore, by including a gelling agent, the ink droplets that have been ejected and landed can be put into a gel state and temporarily fixed (pinned), which makes it easier to form partition walls with fine shapes or high aspect ratios.

[0113] Furthermore, the partition walls formed using the ink of the present invention containing a gelling agent have a matte effect due to the roughness of the partition wall surface, and can reduce the reflectance of light from the viewing side.

[0114] The ink of the present invention may contain only one type of gelling agent, or two or more types of gelling agents.

[0115] Examples of gelling agents according to the present invention include dialkyl ketones, fatty acid esters, fatty acid amides, and oil gelling agents.

[0116] Furthermore, the gelling agent according to the present invention preferably contains at least one compound selected from compounds having a structure represented by the following general formula (G1) or (G2). General formula (G1): R1-CO-R2 General formula (G2): R3-COO-R4 [In the formula, R1 to R4 each independently represent an alkyl chain having 12 or more carbon atoms and a linear portion, which may be branched.]

[0117] The ketone wax having the structure represented by the general formula (G1) above or the ester wax having the structure represented by the general formula (G2) above has a linear or branched hydrocarbon group (alkyl chain) with 12 or more carbon atoms, which increases the crystallinity of the gelling agent and creates more space in the house-of-card structure described below. This makes it easier for the ink medium, such as the polymerizable compound, to be fully enclosed in the space, thereby improving the pinning ability of the ink.

[0118] Furthermore, the number of carbon atoms in R1 to R4 is preferably 26 or less. When the number of carbon atoms is 26 or less, the melting point of the gelling agent does not become excessively high, so there is no need to heat the ink excessively when ejecting it.

[0119] From the above viewpoint, it is particularly preferable that R1 and R2, or R3 and R4, are linear hydrocarbon groups having 12 to 23 carbon atoms.

[0120] Furthermore, from the viewpoint of increasing the gelling temperature of the ink and causing the ink to gel more rapidly after impact, it is preferable that either R1 or R2, or either R3 or R4, is a saturated hydrocarbon group having from 12 to 23 carbon atoms.

[0121] From the above viewpoint, it is more preferable that both R1 and R2, or both R3 and R4, are saturated hydrocarbon groups having 11 or more and less than 23 carbon atoms.

[0122] Examples of ketone waxes having the structure represented by the general formula (G1) above include dilignoceryl ketone (C24-C24), dibehenyl ketone (C22-C22), distearyl ketone (C18-C18), dieicosyl ketone (C20-C20), dipalmityl ketone (C16-C16), dimyristyl ketone (C14-C14), dilauryl ketone (C12-C12), lauryl myristyl ketone, Examples of ketones include ketone (C12-C14), lauryl palmityl ketone (C12-C16), myristyl palmityl ketone (C14-C16), myristyl stearyl ketone (C14-C18), myristyl behenyl ketone (C14-C22), palmityl stearyl ketone (C16-C18), palmityl behenyl ketone (C16-C22), and stearyl behenyl ketone (C18-C22). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

[0123] Commercially available examples of ketone waxes having the structure represented by general formula (G1) include Stearonne (manufactured by Alfa Aeser; Stearon), 18-Pentatriacontanone (manufactured by Alfa Aeser), Hentriacontan-16-one (manufactured by Alfa Aeser), and Kaowax T-1 (manufactured by Kao Corporation).

[0124] Examples of fatty acid or ester waxes having a structure represented by general formula (G2) include behenyl behenate (C21-C22), icosanoic acid icosyl (C19-C20), stearyl stearate (C17-C18), palmityl stearate (C17-C16), lauryl stearate (C17-C12), cetyl palmitate (C15-C16), stearyl palmitate (C15-C Myristate (C13-C18), myristyl myristate (C13-C14), cetyl myristate (C13-C16), octyldodecyl myristate (C13-C20), stearyl oleate (C17-C18), stearyl erucate (C21-C18), stearyl linoleate (C17-C18), and behenyl oleate (C18-C22) and arachidyl linoleate (C17-C20). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

[0125] Commercially available examples of ester waxes having a structure represented by general formula (G2) include Unistar M-2222SL and Sperm Acetate (both manufactured by NOF Corporation, "Unistar" is a registered trademark of the company), Exsepar SS and Exsepar MY-M (both manufactured by Kao Corporation, "Exsepar" is a registered trademark of the company), EMALEX CC-18 and EMALEX CC-10 (both manufactured by Nippon Emulsion Co., Ltd., "EMALEX" is a registered trademark of the company), and Amuleps PC (manufactured by Kokyu Alcohol Kogyo Co., Ltd., "Amuleps" is a registered trademark of the company).

[0126] These commercially available products are often mixtures of two or more types, and may be separated and purified as necessary before being added to the ink. Of these gelling agents, ketone wax, ester wax, higher fatty acid, higher alcohol, and fatty acid amide are preferred from the viewpoint of further enhancing pinning properties.

[0127] The content of the gelling agent is preferably within the range of 0.5 to 5.0% by mass of the total ink. By setting the content of the gelling agent within this range, the solubility and pinning effect of the gelling agent are improved. From the above viewpoint, the content of the gelling agent in the ink is more preferably within the range of 0.5 to 2.5% by mass.

[0128] Furthermore, from the following viewpoint, it is preferable that the gelling agent crystallizes in the ink at a temperature equal to or lower than the gelling temperature of the ink. The gelling temperature is the temperature at which the gelling agent undergoes a phase transition from sol to gel when the ink, which has been solated or liquefied by heating, is cooled, causing a sudden change in the viscosity of the ink. Specifically, the solated or liquefied ink is cooled while its viscosity is measured using a viscoelasticity measuring device (e.g., MCR300, manufactured by Physica), and the temperature at which the viscosity suddenly increases can be determined to be the gelling temperature of the ink.

[0129] When a gelling agent crystallizes in the ink, a structure may be formed in which the ink medium, such as a polymerizable compound, is enclosed in a three-dimensional space formed by the gelling agent crystallized into a plate shape (such a structure will be referred to as a "house of cards structure" hereinafter). When a house of cards structure is formed, the liquid ink medium is retained within the space, making it more difficult for the ink droplets to wet and spread, and improving the pinning ability of the ink.

[0130] To form a house-of-cards structure, it is preferable that the ink medium, such as a polymerizable compound in the ink, and the gelling agent are compatible with each other. On the other hand, if the ink medium, such as a polymerizable compound in the ink, and the gelling agent are phase-separated, it may be difficult to form a house-of-cards structure.

[0131] (Solvents with a normal boiling point of 250°C or less) The ink of the present invention preferably contains 25% or less of solvents with a normal boiling point (boiling point under 1 atmosphere) of 250°C or less. This can prevent damage to the LED chip and reduce the environmental impact. The content of solvents with a normal boiling point of 250°C or less is more preferably 15% or less, and even more preferably 5% or less.

[0132] Examples of solvents having a standard boiling point of 250°C or less include alcohol-based solvents such as methyl alcohol, ethyl alcohol, N-propyl alcohol, and i-propyl alcohol; cellosolve-based solvents such as methoxy alcohol and ethoxy alcohol; carbitol-based solvents such as methoxyethoxyethanol and ethoxyethoxyethanol; ester-based solvents such as ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, and ethyl lactate; ketone-based solvents such as acetone, methyl isobutyl ketone, and cyclohexanone; methoxyethyl acetate, propylene glycol monomethyl ether acetate, 3-methoxy-3-methyl-1-butyl acetate, 3-methoxybutyl acetate, methoxybutyl acetate, ethoxyethyl acetate, and ethyl cellosolve acetate; carbitol acetate solvents such as methoxyethoxyethyl acetate, ethoxyethoxyethyl acetate, and butyl carbitol acetate (BCA); ether solvents such as diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, and tetrahydrofuran; aprotic amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; lactone solvents such as γ-butyrolactone; unsaturated hydrocarbon solvents such as benzene, toluene, xylene, and naphthalene; and saturated hydrocarbon solvents such as N-heptane, N-hexane, and N-octane.

[0133] (Other ingredients) The ink of the present invention may further contain other components including a polymerization inhibitor and a surfactant, as long as the effects of the present invention are obtained. Only one of these components may be contained in the ink of the present invention, or two or more types may be contained.

[0134] Examples of the polymerization inhibitor include (alkyl)phenols, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxyamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutyl cresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, and cyclohexanone oxime.

[0135] Examples of commercially available polymerization inhibitors include Irgastab UV10 (manufactured by BASF) and Genorad 18 (manufactured by Rahn AG).

[0136] The amount of the polymerization inhibitor can be set arbitrarily as long as the effects of the present invention are obtained, and can be, for example, 0.001% by mass or more and less than 1.0% by mass of the total ink.

[0137] Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; and silicone-based and fluorine-based surfactants.

[0138] Examples of silicone surfactants include polyether-modified polysiloxane compounds, specifically Tego rad 2250 (manufactured by Evonik), KF-351A, KF-352A, KF-642, and X-22-4272 (all manufactured by Shin-Etsu Chemical Co., Ltd.), BYK307, BYK345, BYK347, and BYK348 (all manufactured by BYK-Chemie, "BYK" being a registered trademark of the company), and TSF4452 (manufactured by Momentive Performance Materials).

[0139] Fluorine-based surfactants refer to surfactants in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrophobic groups of ordinary surfactants have been replaced with fluorine. Examples of fluorine-based surfactants include Megafac F (manufactured by DIC Corporation, "Megafac" is a registered trademark of DIC), Surflon (manufactured by AGC Sei Chemical Co., Ltd., "Surflon" is a registered trademark of AGC Sei Chemical Co., Ltd.), Fluorad FC (manufactured by 3M Corporation, "Fluorad" is a registered trademark of 3M), Monflor (manufactured by Imperial Chemical Industries, Ltd.), Zonyls (manufactured by E.I. duPont Nemerus & Co., Ltd.), Licowet VPF (manufactured by Lubbewerke-Hoechst), and FTERGENT (manufactured by Neos Corporation, "FTERGENT" is a registered trademark of 3M).

[0140] The amount of surfactant can be set arbitrarily as long as the effects of the present invention can be obtained, and can be, for example, 0.001% by mass or more and less than 1.0% by mass of the total ink.

[0141] 1.3 Sol-gel phase transition of ink The ink of the present invention is characterized by undergoing a sol-gel phase transition depending on temperature. In the present invention, the term "sol-gel phase transition" refers to a reversible change from a fluid sol state at high temperatures to a non-fluid gel state at low temperatures, with the sol-gel phase transition point as the boundary.

[0142] The viscosity of the ink of the present invention at 25°C is 1 to 1 × 10 4A viscosity within the Pa·s range is preferable in that the ink is sufficiently gelled when it lands and is cooled to room temperature, resulting in good pinning properties.

[0143] Furthermore, from the viewpoint of further improving the ejection properties from an inkjet head, the viscosity of the ink of the present invention at 80° C. is preferably within the range of 3 to 20 mPa·s, and more preferably within the range of 7 to 9 mPa·s.

[0144] The ink of the present invention preferably has a sol-gel phase transition point in the range of 40°C or higher but lower than 100°C. If the sol-gel phase transition point is 40°C or higher, the ink will gel quickly after landing, resulting in higher pinning properties. Furthermore, if the sol-gel phase transition point is lower than 100°C, the ink will be easier to handle and have higher ejection stability. From the viewpoint of enabling the ink to be ejected at lower temperatures and reducing the load on the inkjet device, the sol-gel phase transition point of the ink of the present invention is more preferably in the range of 40 to 60°C.

[0145] The viscosity at 80°C, the viscosity at 25°C, and the sol-gel phase transition point of the ink of the present invention can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer.

[0146] In the present invention, the ink viscosity and sol-gel phase transition point are values ​​obtained by the following method. The ink is heated to 100°C and the viscosity is measured using a stress-controlled rheometer, Physica MCR301 (cone-plate diameter: 75 mm, cone angle: 1.0°), manufactured by Anton Paar. The ink is then cooled to 20°C at a shear rate of 11.7 (1 / s) and a cooling rate of 0.1°C / s to obtain a viscosity-temperature curve. The viscosities at 80°C and 25°C can be determined by reading the viscosities at 80°C and 25°C, respectively, from the viscosity-temperature curve. The sol-gel phase transition point can be determined as the temperature at which the viscosity reaches 200 mPa·s from the viscosity-temperature curve.

[0147] <1.4 Ink color> The color of the ink of the present invention is not particularly limited, and a coloring material corresponding to the color of the partition walls to be formed may be used. The color of the partition walls is preferably white to improve reflectance and brightness, and black to improve contrast, so the ink color is preferably white or black. Gray is also preferable for the color of the partition walls to control reflectance and contrast, so gray ink can also be used. The ink color can be adjusted by the content of each coloring material.

[0148] 1.5 Ink preparation method The ink of the present invention can be prepared by mixing the above-mentioned photopolymerizable composition, coloring material, gelling agent, etc., while heating using a known method.

[0149] <1.6 Inkjet ink set for partition wall formation> The inkjet ink set for partition wall formation of the present invention (hereinafter also simply referred to as "ink set") is an inkjet ink set for forming partition walls between LED chips in an LED device, and comprises a first inkjet ink for partition wall formation and a second inkjet ink for partition wall formation, wherein the first inkjet ink for partition wall formation contains a photopolymerizable composition, a white colorant, and a gelling agent, and undergoes a sol-gel phase transition depending on the temperature, and the second inkjet ink for partition wall formation contains a photopolymerizable composition, a black colorant, and a gelling agent, and also undergoes a sol-gel phase transition depending on the temperature.

[0150] The components contained in the first inkjet ink for forming partition walls and the second inkjet ink for forming partition walls are as described above. By using such an ink set, partition walls composed of white partition walls and black partition walls, which will be described later, can be formed.

[0151] The color of the inkjet ink for forming the first partition wall is preferably white or gray, and particularly preferably white. The color of the inkjet ink for forming the second partition wall is preferably black. By using such an ink set, it is possible to form partition walls composed of white or gray partition walls and black partition walls, as described below. The color of the ink can be adjusted by the content of the coloring material of each color.

[0152] <2. LED device manufacturing method> The method for manufacturing an LED device of the present invention is a method for manufacturing an LED device having partitions between LED chips, and includes a partition formation step of patterning the partitions by an inkjet method, and is characterized in that the partition formation step uses an inkjet ink for forming partitions, which contains a photopolymerizable composition, a colorant, and a gelling agent, and which undergoes a sol-gel phase transition depending on temperature.

[0153] The ink-jet ink for forming partition walls used in the method for manufacturing an LED device is as described above.

[0154] In the partition wall formation process, the partition walls are patterned using the inkjet method. Specifically, ink droplets are ejected from an inkjet head and land on the positions on the substrate where the partition walls are to be formed, creating a pattern. The landed ink is irradiated with active energy rays to harden the ink, forming the partition walls. By patterning the partition walls using the inkjet method, the LED chips are not damaged as in the case of photolithography, and it is possible to form partition walls with fine shapes that are difficult to achieve using screen printing or coating methods.

[0155] The ejection method from the inkjet head may be either an on-demand method or a continuous method. On-demand inkjet heads may be any of electromechanical conversion types such as single cavity type, double cavity type, bender type, piston type, shear mode type, and shared wall type, and electrothermal conversion types such as thermal inkjet type and bubble jet type (Bubble Jet is a registered trademark of Canon Inc.).

[0156] Discharging ink droplets from an inkjet head in a heated state can improve discharge stability. The ink temperature when discharged is preferably within the range of 40 to 100°C, and more preferably within the range of 40 to 90°C to further improve discharge stability. In particular, it is preferable to discharge the ink at a temperature that results in a viscosity of the ink within the range of 7 to 15 mPa·s, more preferably within the range of 8 to 13 mPa·s.

[0157] The method for heating the ink is not particularly limited. For example, at least one of the ink supply system, such as the ink tank constituting the head carriage, the supply pipe, and the anterior ink tank immediately before the head, the piping with a filter, and the piezo head, can be heated by a panel heater, a ribbon heater, or heated water.

[0158] The amount of ink droplets ejected is preferably within the range of 2 to 20 pL.

[0159] The active energy rays can be selected from, for example, electron beams, ultraviolet rays, α rays, γ rays, and X-rays, and are preferably ultraviolet rays.

[0160] The ink may be cured by irradiation with active energy rays all at once after all of the inks required for forming the partition walls have landed, or may be cured in multiple steps by repeating the ink ejection and the irradiation with active energy rays. In the case of forming high partition walls or highly precise partition walls, it is preferable to cure the ink in multiple steps.

[0161] When irradiating ultraviolet rays as active energy rays, this can be done under conditions of a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology Co., Ltd. By using an LED as the light source, it is possible to prevent poor ink curing caused by the ink melting due to the radiant heat of the light source.

[0162] When ultraviolet rays are irradiated as active energy rays, the peak irradiance can be adjusted appropriately depending on the material and amount of ink to be cured, but is, for example, 0.1 to 4.0 W / cm 2 The range may be:

[0163] The amount of light when irradiating ultraviolet rays as active energy rays can be adjusted appropriately depending on the material and amount of ink to be cured, but is, for example, 100 to 5000 mJ / cm 2 It can be within a range.

[0164] In the partition wall forming process, partition walls of any color can be formed. For example, in an embodiment, when the partition wall forming process includes at least a white partition wall forming process, white partition walls can be formed to improve brightness. In another embodiment, when the partition wall forming process includes at least a black partition wall forming process, black partition walls can be formed to improve contrast. Furthermore, in another embodiment, when the partition wall forming process includes at least a gray partition wall forming process, gray partition walls can be formed to control reflectance and contrast.

[0165] In order to simultaneously improve brightness and contrast, a partition wall composed of a white partition wall and a black partition wall located thereon may be formed in one embodiment, which includes a white partition wall forming step and a black partition wall forming step in which a black partition wall is formed on the white partition wall formed in the white partition wall forming step. In this case, the irradiation of active energy rays may be performed in each of the white partition wall forming step and the black partition wall forming step, or may be performed together after the black partition wall forming step. Furthermore, in this embodiment, a gray partition wall forming step may be added between the white partition wall forming step and the black partition wall forming step, or the gray partition wall forming step may be performed instead of the white partition wall forming step.

[0166] <3 LED devices> The LED device of the present invention is an LED device having partition walls between LED chips, characterized in that the partition walls contain a cured product of a photopolymerizable composition, a coloring material, and a gelling agent.

[0167] The size, color, and pattern of the partition walls are as previously described.

[0168] The method for forming the partition walls is not limited to the inkjet method described above, but they may also be formed by photolithography, coating, screen printing, or the like.

[0169] The gelling agent contained in the partition walls is the same as that contained in the ink described above. By incorporating a gelling agent, the partition walls of the LED device have a rough surface, which improves adhesion to the transparent encapsulant filled on the LED chip and improves the high-temperature durability of the LED device. Furthermore, the rough surface of the partition walls provides a matte finish, reducing the reflectance of light from the viewing side.

[0170] The cured product of the photopolymerizable composition contained in the partition walls is a resin obtained by curing a photopolymerizable composition similar to the photopolymerizable composition contained in the ink described above by irradiation with active energy rays. The coloring material contained in the partition walls is similar to the coloring material contained in the ink described above.

[0171] In the LED device of the present invention, a transparent sealant is preferably filled on the LED chip. This prevents the LED chip from deteriorating due to moisture. Resins such as polyvinyl carbazole and epoxy resins can be used as the transparent sealant.

[0172] The LED chip may be a known one, or a mini LED chip or a micro LED chip.

[0173] The LED device of the present invention may be provided with any of a substrate, a cover glass, electrodes, circuits, wiring, and other components without any particular limitations, and may be provided with any known components. If necessary, the LED device may also be provided with a wavelength conversion layer or a color filter.

[0174] The color of the substrate is preferably black because regions where partitions or the like are not formed can affect contrast. In particular, when partitions are formed in a pattern in which there are regions where partitions are not formed between pixels, as shown in Figure 7, a black substrate can further improve contrast. As a black substrate, for example, a substrate formed using a black material or a substrate that has been blackened by sputtering or the like can be used. [Example]

[0175] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

[0176] <Preparation of pigment dispersion> Black pigment dispersion, white pigment dispersion A, and white pigment dispersion B were prepared according to the following procedure.

[0177] (Preparation of Black Pigment Dispersion) 71.0 parts by weight of dipropylene glycol diacrylate and 9.0 parts by weight of a dispersant (Ajinomoto Fine-Techno Co., Ltd., Ajisper PB824) were placed in a stainless steel beaker and stirred for 1 hour while heating on a hot plate at 65°C to dissolve the dispersant. After the resulting liquid was cooled to room temperature, 20.0 parts by weight of Pigment Black 7 (Mitsubishi Chemical Corporation, MA77) was added as a black pigment to obtain a mixed liquid. The resulting mixed liquid was placed in a glass bottle together with 200 g of zirconia beads (diameter: 0.5 mm), sealed, and dispersed for 5 hours using a paint shaker. The zirconia beads were then removed from the mixed liquid to obtain a black pigment dispersion.

[0178] (Preparation of White Pigment Dispersion A) 70.7 parts by weight of tripropylene glycol diacrylate (Miramer M200, manufactured by Miwon Co., Ltd.; "Miramer" is a registered trademark of the company) and 8 parts by weight of a dispersant (BYKJET-9151, manufactured by BYK Co., Ltd.; "BYKJET" is a registered trademark of the company) were placed in a stainless steel beaker and stirred for 1 hour while heating on a hot plate at 65°C to dissolve the dispersant. After the resulting liquid was cooled to room temperature, 21.3 parts by weight of titanium dioxide (TCR-52, manufactured by Sakai Chemical Industry Co., Ltd.) was added as a white pigment to obtain a mixed liquid. The resulting mixed liquid was placed in a glass bottle together with 220 g of zirconia beads (diameter: 0.5 mm), sealed, and dispersed for 5 hours using a paint shaker. The zirconia beads were then removed from the mixed liquid to obtain White Pigment Dispersion Liquid A.

[0179] (Preparation of White Pigment Dispersion B) 70.7 parts by weight of tripropylene glycol diacrylate (Miramer M200, manufactured by Miwon Co., Ltd.; "Miramer" is a registered trademark of the company) and 8 parts by weight of a dispersant (BYKJET-9151, manufactured by BYK Co., Ltd.; "BYKJET" is a registered trademark of the company) were placed in a stainless steel beaker and stirred for 1 hour while heating on a hot plate at 65°C to dissolve the dispersant. After the resulting liquid was cooled to room temperature, 21.3 parts by weight of zirconium oxide (Zirconeo, manufactured by ITEC Co., Ltd.) was added as a white pigment to obtain a mixed liquid. The resulting mixed liquid was placed in a glass bottle together with 220 g of zirconia beads (diameter: 0.5 mm), sealed, and dispersed for 5 hours using a paint shaker. The zirconia beads were then removed from the mixed liquid to obtain White Pigment Dispersion B.

[0180] <Ink Preparation> Black pigment ink and white pigment ink were prepared according to the following procedure.

[0181] (Preparation of Black Pigment Inks 1 to 7) The materials shown in Table I were placed in a stainless steel beaker and stirred for 1 hour while being heated to 80°C on a hot plate. The resulting solution was filtered with an ADVATEC Teflon (registered trademark) 3 μm membrane filter while still being heated, to obtain black pigment inks 1 to 7.

[0182] [Table 1]

[0183] The details of the materials shown in Table I are as follows: DPGDA: Dipropylene glycol diacrylate HDDA: 1,6-hexanediol diacrylate 3PO-TMPTA: 3PO-modified trimethylolpropane triacrylate 9EO-TMPTA: 9EO modified trimethylolpropane triacrylate PEGDA(600): Polyethylene glycol #600 diacrylate 4EO-PETA: 4EO modified pentaerythritol tetraacrylate DAROCURE TPO: 2,4,6-trimethylbenzoin diphenylphosphine oxide, manufactured by BASF Speedcure ITX: 2-isopropylthioxanthone, manufactured by Lambson Irgastab UV-10: BASF Black pigment dispersion: the black pigment dispersion prepared above Kaowax T1: a compound having a structure represented by the above general formula (G1), distearyl ketone, manufactured by Kao Corporation Unistar M-2222SL: a compound having a structure represented by the above general formula (G2), behenyl behenate, manufactured by NOF Corporation

[0184] (Preparation of White Pigment Inks 1 to 7) The materials shown in Table II were placed in a stainless steel beaker and stirred for 1 hour while being heated to 80°C on a hot plate. The resulting solution was filtered with an ADVATEC Teflon (registered trademark) 3 μm membrane filter while still being heated, to obtain white pigment inks 1 to 7.

[0185] [Table 2]

[0186] The details of the materials shown in Table II are as follows: 6EO-TMPTA: 6EO-modified trimethylolpropane triacrylate 4EO-HDDA: 4EO-modified hexanediol diacrylate TPGDA: Tripropylene glycol diacrylate DAROCURE TPO: 2,4,6-trimethylbenzoin diphenylphosphine oxide, manufactured by BASF Irgacure 819: BASF Irgastab UV-10: BASF KF-352: Shin-Etsu Chemical Co., Ltd. White pigment dispersion A: The prepared white pigment dispersion A White pigment dispersion B: The prepared white pigment dispersion B Kaowax T1: A compound having the structure represented by the general formula (G1), distearyl ketone, manufactured by Kao Corporation Unister M-2222SL: A compound having the structure represented by the general formula (G2), behenyl behenate, manufactured by NOF Corporation

[0187] (Viscosity and sol-gel phase transition point) The viscosity of the prepared ink at 25°C, the viscosity at 80°C, and the sol-gel phase transition point were determined by the following method. The ink was heated to 100°C, and while measuring the viscosity with a stress-controlled rheometer Physica MCR301 (diameter of the cone plate: 75 mm, cone angle: 1.0°), manufactured by Anton Paar, the ink was cooled to 20°C under the conditions of a shear rate of 11.7 (1 / s) and a temperature decrease rate of 0.1°C / s to obtain a viscosity-temperature change curve. The viscosity at 25°C and the viscosity at 80°C were determined by reading the viscosity at 25°C and the viscosity at 80°C from the viscosity-temperature change curve. The sol-gel phase transition point was determined as the temperature at which the viscosity becomes 200 mPa·s in the viscosity-temperature change curve. The viscosity at 25°C, the viscosity at 80°C, and the sol-gel phase transition point of each ink are as shown in Table I and Table II.

[0188] <Fabrication of LED device> An LED device was fabricated by the following procedure.

[0189] (Fabrication of LED devices 1 to 16) Referring to the method described in paragraphs

[0091] to

[0106] of the specification of JP-A-2021-110875, red, green, and blue LED chips were arranged on a substrate by the following procedure to form a partitionless LED device.

[0190] The LED chips used were micro LED chips measuring 100 μm x 100 μm x 100 μm. The number of pixels consisting of three-color micro LED chips was 80 x 80, so a total of 80 x 80 x 3 micro LED chips were used. The micro LED chips within a pixel were arranged horizontally with the three color micro LED chips lined up, as shown in Figures 4 and 7. The spacing between adjacent micro LED chips within the same pixel was 250 μm. The pixel pitch was 1300 μm.

[0191] The drive substrate was a 200mm x 200mm alkali-free glass substrate with TFTs (thin film transistors), wiring, and Cu electrode pads corresponding to the number of micro LED chips formed on it. The drive substrate was blackened by sputtering except for the bonding area with the micro LED chips.

[0192] The relay substrate was a non-alkali glass substrate of the same size as the drive substrate and 0.7 mm thick. PDMS (dimethylpolysiloxane) resin was formed on the relay substrate to a thickness of 10 μm.

[0193] The PDMS resin was formed by applying a uniform thickness of PDMS resin to the substrate surface using a laminating method, and then heating it in an oven at 100°C for 1 hour to thermally crosslink the PDMS resin. The PDMS resin was blended with Shin-Etsu Silicone SIM360 and CAT360 manufactured by Shin-Etsu Chemical Co., Ltd. to adjust the hardness of the finished product. The hardness of the finished product (after thermal crosslinking) was Shore A60.

[0194] The micro LED chip was diced from the sapphire substrate on which the semiconductor layer was formed, transferred to a holding substrate, and then transferred to an intermediate substrate. A chip-side electrode was formed on the micro LED chip, and a 5 μm high solder microbump was formed on the chip-side electrode. SAC (SnAgCu) solder was used.

[0195] When transferring the micro LED chips to the intermediate substrate, a stamp was used to arrange the chips on the intermediate substrate.

[0196] Next, the resin residue remaining on the micro LED chip and chip-side electrodes on the relay substrate was removed using an oxygen asher, and then the resulting surface was treated with Ar plasma.

[0197] Next, after aligning the drive substrate and relay substrate, they were batch bonded at the positions where their electrodes overlapped at a temperature below the solder melting point, temporarily joining the chip electrodes and drive substrate electrodes via solder.

[0198] Next, the relay substrate was peeled off and removed.

[0199] Next, flux was applied to the surface of the drive board where the micro LED chip was temporarily bonded, and the surface was heated in a reflow furnace to a temperature above the solder melting point. The micro LED chip was mounted by this reflow.

[0200] By the above procedure, red, green, and blue micro LED chips were arranged on the substrate to form an LED device without partitions.

[0201] Next, using the black pigment ink 1 prepared above, partition walls with a width of 200 μm and a total height of 100 μm were formed to cover the periphery of each micro LED chip of the formed LED device without partition walls, in the pattern shown in Figure 7. The specific procedure is as follows.

[0202] Using an inkjet device, droplets of black pigment ink 1 were ejected and patterned to form uncured partition walls with a height of 20 μm after curing. The temperature of the ink when ejected was adjusted to 80°C. The amount of ink droplets when ejected was 5 pL. A light intensity of 1000 mJ / cm was applied to the uncured partition walls. 2 The film was irradiated with ultraviolet light at 4000 kJ / cm to form partition walls having a height of 20 μm.

[0203] Next, droplets of black pigment ink 1 were ejected onto the formed partition walls in the same manner as above to form uncured partition walls with a height of 20 μm after curing. A light intensity of 1000 mJ / cm was applied to the uncured partition walls. 2 The height of the partition walls was set to 40 μm.

[0204] The above steps were repeated to form barrier ribs with a width of 200 μm and a total height of 100 μm.

[0205] By the above procedure, a partition wall forming step was carried out in which the partition walls were patterned by the ink jet method.

[0206] Next, polyvinylcarbazole was filled onto the micro LED chip as a transparent encapsulant using a dispenser, and the chip was then attached to a cover glass.

[0207] By the above procedure, LED device 1 was fabricated.

[0208] In the production of the above LED device 1, the ink and transparent sealant were changed as shown in Table III to produce LED devices 2 to 16.

[0209] (Fabrication of LED devices 17 to 24) In the same manner as above, red, green, and blue micro LED chips were arranged on the substrate to form an LED device without a partition formed thereon.

[0210] Next, using the white pigment ink 1 and black pigment ink 1 prepared above, partition walls with a width of 200 μm and a total height of 100 μm were formed so as to cover the periphery of each micro LED chip of the formed LED device without partition walls, in the pattern shown in Figure 7. The specific procedure is as follows.

[0211] Droplets of white pigment ink 1 were ejected using an inkjet device, and while patterning, uncured partition walls with a height of 20 μm after curing were formed. The temperature of the ink when ejected was adjusted to 80°C. The amount of ink droplets when ejected was 5 pL. A light intensity of 1000 mJ / cm was applied to the uncured partition walls. 2 The film was irradiated with ultraviolet light at 4000 kJ / cm to form partition walls having a height of 20 μm.

[0212] Next, droplets of white pigment ink 1 were ejected onto the formed partition walls in the same manner as above to form uncured partition walls with a height of 20 μm after curing. A light intensity of 1000 mJ / cm was applied to the uncured partition walls. 2 The height of the partition walls was set to 40 μm.

[0213] The above steps were repeated to form white barrier ribs with a width of 200 μm and a total height of 80 μm.

[0214] Next, droplets of black pigment ink 1 were ejected onto the white partition walls formed above to form uncured partition walls with a height of 20 μm after curing. A light intensity of 1000 mJ / cm was applied to the uncured partition walls. 2 The resulting black barrier ribs were 200 μm wide and 100 μm high in total.

[0215] By the above-described procedure, a barrier rib forming process was carried out, which included a white barrier rib forming process and a black barrier rib forming process in which black barrier ribs were formed on the white barrier ribs formed in the white barrier rib forming process.

[0216] Next, polyvinylcarbazole was filled as a transparent sealant onto the LED chip using a dispenser, and the chip was then attached to a cover glass.

[0217] By the above procedure, the LED device 17 was fabricated.

[0218] In the production of the above LED device 17, the ink and transparent sealant were changed as shown in Table III to produce LED devices 18 to 24.

[0219] [Table 3]

[0220] <Evaluation> The LED device fabricated above was evaluated as follows.

[0221] (brightness) The LED devices were turned on and their luminance was measured. For LED devices 1 to 8, the luminance of LED device 1 was set to 100, and the relative luminance value compared to that was calculated to obtain the relative luminance. Similarly, for LED devices 9 to 16, the luminance of LED device 9 was set to 100, and for LED devices 17 to 24, the luminance of LED device 17 was set to 100 to calculate the relative luminance.

[0222] The calculated relative luminance was evaluated according to the following criteria, and the evaluation results are shown in Table III. ○: Relative luminance is 80 or more ×: Relative luminance is less than 80

[0223] (High temperature durability) The LED device was placed in a thermostat at a temperature of 85°C and a relative humidity of 85% and stored for 1500 hours. The luminance retention rate [%] was calculated using the following formula from the luminance before and after 1500 hours of storage. Brightness maintenance rate [%] = Brightness after storage / Brightness before storage x 100

[0224] The high temperature durability was evaluated based on the calculated luminance maintenance rate [%] according to the following evaluation criteria. The evaluation results are shown in Table III. ○: Brightness maintenance rate is 95% or more ×: Luminance maintenance rate is less than 95%

[0225] (Transparent sealant adhesion) The ink used to make the LED device was applied to the glass to create a solid film with a thickness of 20 μm, and the light intensity was 1000 mJ / cm. 2 The ink was applied to the cured solid film and cured under ultraviolet light at a light intensity of 1000 mJ / cm.2 The process of irradiating the sample with ultraviolet light was repeated to produce a solid film with a total thickness of 100 μm. The transparent encapsulant (polyvinyl carbazole or epoxy resin) used in the production of the LED device was applied to the top layer of the solid film to produce a solid film with a thickness of 100 μm. Using the sample, a cross-cut test was performed in accordance with JIS K 5600-5-6, and the sample was evaluated using the following six-level classification (0 to 5). The evaluation results are shown in Table III.

[0226] 0: The edges of the cut are completely smooth and there is no peeling on any of the grids. 1: Small peeling of the coating at the intersection of the cuts. The affected area of ​​the cross cuts does not clearly exceed 5%. 2: The coating is peeling along the edges of the cuts and / or at the intersections. The cross-cut area is clearly more than 5% affected but not more than 15%. 3: The coating has partially or completely peeled off significantly along the edges of the cuts and / or partially or completely peeled off in various areas of the mesh. The cross-cut area is clearly more than 15% affected but not more than 35%. 4: The coating has partially or completely peeled off significantly along the edges of the cuts and / or partially or completely peeled off in several sections. Not more than 35% of the cross-cut area is affected. 5: Any degree of peeling that cannot be classified as category 4.

[0227] These results confirm that the inkjet ink for partition wall formation of the present invention, by containing a gelling agent, can form partition walls that can improve the adhesion between the partition walls and the transparent encapsulant and improve the high-temperature durability of the LED device. [Industrial Applicability]

[0228] The present invention can be used in an inkjet ink for forming a partition wall, which can form a partition wall between LED chips and can improve the high-temperature durability of the LED device, an inkjet ink set for forming a partition wall, a method for manufacturing an LED device using the inkjet ink and the inkjet ink set, and an LED device with improved high-temperature durability. [Explanation of symbols]

[0229] 1 LED device 2 boards 3R red LED chip 3G Green LED Chip 3B blue LED chip 4 Bulkhead 4Wh white partition wall 4Bl black bulkhead 5. Transparent sealant 6 Coverslips

Claims

1. 1. An ink-jet ink for forming partition walls, for forming partition walls between LED chips of an LED device, comprising: A photopolymerizable composition (excluding a case where the composition contains a photopolymerizable compound having no acidic group and a photopolymerizable compound having an acidic group), a colorant, and a gelling agent, Sol-gel phase transition occurs depending on the temperature. The ink-jet ink for forming partition walls, characterized in that the color material contains a white color material or a black color material.

2. The photopolymerizable composition contains a (meth)acrylate compound as a component. The ink-jet ink for forming partition walls according to claim 1 .

3. Viscosity at 25°C is 1 to 1 x 10 ４ Pa s range, and A sol-gel phase transition point in the range of 40°C or higher and lower than 100°C The ink-jet ink for forming partition walls according to claim 1 or 2.

4. The gelling agent contains at least one compound selected from compounds having a structure represented by the following general formula (G1) or (G2): The ink-jet ink for forming partition walls according to claim 1 or 2. General form (G1): R １ -CO-R ２ General form (G2): R ３ -COO-R ４ [In the formula, R １ ~R ４ each independently represents an alkyl chain having 12 or more carbon atoms, which has a linear portion and may be branched.

5. The gelling agent is contained in the range of 0.5 to 5% by mass based on the total amount of the ink. The ink-jet ink for forming partition walls according to claim 1 or 2.

6. An LED device having a partition between LED chips, the partition walls contain a cured product of a photopolymerizable composition (excluding a case where the composition contains a photopolymerizable compound having no acidic group and a photopolymerizable compound having an acidic group), a colorant, and a gelling agent; The partition walls are composed of at least white partition walls or black partition walls. An LED device characterized by:

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