Sealant for display device, cured product thereof and display device

Abstract

A sealant for display elements contains (A) a cationic polymerizable compound, (B) a cationic polymerization initiator, and (C) a leveling agent, wherein the droplet diameter ratio R of the sealant for display elements after being refrigerated at 5°C for 7 days is 0.5 or more and 1.1 or less.

Description

Technical Field

[0001] This invention relates to a sealant for display elements, its cured form, and a display device. Prior Technology

[0002] In the field of display elements, research has been conducted on improving the properties of sealants. The following explanation uses an organic electroluminescence (EL) display device as an example.

[0003] Organic EL elements are increasingly being used in displays and lighting devices due to their low power consumption. However, organic EL elements are susceptible to degradation by atmospheric moisture or oxygen, therefore they are sealed using various sealing components. Various materials have been investigated as materials for this sealing process.

[0004] As a method for applying sealant to organic EL display elements, inkjet printing is a suitable method, where the sealant for organic EL display elements using inkjet printing requires a high level of storage stability. The reasons are as follows.

[0005] When applying sealant to display elements using inkjet printing, the process is as follows: First, the sealant is introduced into the inkjet cartridge, then the cartridge is placed in the inkjet printer, and the sealant is applied to the object being coated using inkjet printing. Here, depending on the manufacturing process, the sealant may be stored in the cartridge for several days to several months. During this period, the ambient temperature may change, and consequently, the cartridge may experience temperature fluctuations during inkjet printing.

[0006] If the viscosity or hardening properties of the sealant change due to long-term storage or temperature fluctuations during storage, the sealant's adhesion to the inkjet head or its post-adhesion hardening behavior will change, resulting in reduced yield. Therefore, the sealant's storage stability is required. As a prior art for improving the storage stability of such sealants, the techniques described in Patent Document 1 and Patent Document 2 are known.

[0007] Patent document 1 describes an ultraviolet-curable resin composition containing a photopolymerizable compound and a photopolymerization initiator. The differential scanning calorimetry (DSC) curve of the photocured product has a peak with a peak in the range of 30°C to 260°C. The photocured product is obtained by irradiating a 10 μm thick coating with light of a peak wavelength of 395 nm under atmospheric conditions of normal temperature and pressure with a cumulative light intensity of 800 mJ / cm² or more and 4000 mJ / cm² or less (claim 1).

[0008] Patent document 2 describes an ultraviolet-curable resin composition in which, when a coating of the ultraviolet-curable resin composition with a thickness of 10 μm is irradiated with ultraviolet light with a peak wavelength of 395 nm in the range of cumulative light intensity of 800 mJ / cm2 or more and 4000 mJ / cm2 or less, the irradiation intensity of the ultraviolet light is 1 W / cm2 or less, and the reaction rate of the polymerizable compound in the coating is less than 70% (claim 1). [Existing Technical Documents] [Patent Literature]

[0009] Patent Document 1: Japanese Patent Application Publication No. 2020-105482 Patent Document 2: Japanese Patent Application Publication No. 2020-105483 Summary of the Invention

[0010] [The problem that the invention aims to solve] However, the inventors studied the technologies described in the aforementioned patent documents and determined that it is difficult to achieve a sufficiently high level of preservation stability using the technologies in Patent Documents 1 and 2. In these technologies, as described in their embodiments, preservation stability is evaluated based on whether the ink can be continuously sprayed for 10 minutes. If it can be continuously sprayed for 10 minutes without problems, it is judged to have good preservation stability; if ink (composition) adheres to the inkjet head, it is judged to have poor preservation stability (paragraph 0283 of Patent Document 1, paragraph 0219 of Patent Document 2). Regarding the preservation stability judged by this standard, it is believed that the technologies in Patent Documents 1 and 2 can be improved. However, in recent years, there has been a demand for higher performance than before for sealants or sealant films obtained from sealants, and even organic EL elements, and a demand to minimize deviations. To meet these requirements, it is insufficient to merely suppress the adhesion of ink (composition) to the inkjet head; a higher level of sealant stability is required.

[0011] Furthermore, in recent years, methods containing leveling agents have been frequently used to further improve the performance of sealing resin compositions. In the production of such sealing resin compositions containing leveling agents, the inventors' research has revealed previously unrecognized issues. Specifically, it has been found that the properties of the sealing resin composition subtly change during transport, thereby altering the inkjet coating characteristics or the properties of the resulting cured product.

[0012] Based on the above, the present invention imparts a high level of storage stability to sealants for display elements, including sealing resin compositions containing leveling agents. [Methods for solving problems]

[0013] According to the present invention, a sealant, a hardener, and a display device for display elements are provided as shown below. [1] A sealant for display elements, comprising the following components (A) to (C): (A) Cationic polymers, (B) Cationic polymerization initiators, and (C) Leveling agent, in the sealant for the display element. The droplet diameter ratio R of the sealant for the display element, measured in the following order, is 0.5 or more and 1.1 or less. [Testing order] (i) After setting the sealant for the display element to 23°C, a portion of the sealant for the display element is collected, and the sealant for the display element is inkjet coated onto the SiN substrate under the following conditions; (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element is measured; the measurement result is set as D1. (ii) After transferring 9 g to 11 g of the sealant for the display element, which was set to 23°C in step (i), into a 19 mL glass container, tighten the container cap; refrigerate the container containing the sealant for the display element at 5°C for 7 days; (iii) The sealant for the display element collected after refrigeration in step (ii) is then inkjet coated onto the SiN substrate under the following conditions; (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element was measured; the measurement result was set as D2. (iv) Calculate the drop diameter ratio R = D2 / D1 based on D1 and D2. [2] A sealant for display elements as described in [1], wherein The component (A) comprises one or both of an epoxy compound and an oxetane compound. [3] A sealant for display elements as described in [1] or [2], wherein The component (C) is selected from one or more of the group consisting of silicone polymers and acrylate polymers. [4] A sealant for display elements as described in any one of [1] to [3], wherein The component (C) is a silicone polymer having an intramolecular polymethylsiloxane structure or a polydimethylsiloxane structure. [5] A sealant for display elements as described in any one of [1] to [4], wherein The component (C) is a polymer containing structural units derived from alkyl (meth)acrylates. [6] A sealant for a display element as described in any one of [1] to [5], wherein The content of component (C) is 0.01% by mass or more and 5% by mass or less relative to 100% by mass of component (A). [7] A sealant for a display element as described in any one of [1] to [6], wherein The component (B) is a photocationic polymerization initiator that generates a cationic species that initiates polymerization by means of light. [8] A sealant for a display element as described in any one of [1] to [7], wherein The viscosity measured at 25°C and 20 rpm using an E-type viscometer is above 5 mPa·s and below 80 mPa·s. [9] A sealant for display elements as described in any one of [1] to [8], Sealing for organic EL display elements.

[10] A hardener is formed by hardening a display element as described in any one of [1] to [9] with a sealant.

[11] A display device, comprising: substrate; A display element is disposed on the substrate; and A sealing layer covers the display element, and The sealing layer comprises a hardened form of a sealant for display elements as described in any one of [1] to [9]. [The effects of the invention]

[0014] According to the present invention, a sealant for display elements with a high level of preservation stability is provided. Simple Explanation of the Diagram

[0015] Figure 1 is a cross-sectional view of an example of the structure of an organic EL display device in an embodiment. Implementation

[0016] The embodiments of the present invention will now be described using drawings. Furthermore, in all drawings, common symbols are used to denote the same constituent elements, and descriptions may be omitted as appropriate. Additionally, in this embodiment, each component may be used individually or in combination with two or more components. Furthermore, the tilde "~" indicating a numerical range signifies above or below, and includes both the upper and lower limits. Also, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid.

[0017] (Sealant for display components) In this embodiment, the sealant for display elements (hereinafter also suitable for simplification as "sealant") contains the following components (A) to (C). (A) Cationic polymeric compounds (B) Cationic polymerization initiator (C) Leveling agent Furthermore, the droplet diameter ratio R of the sealant for display elements, measured in the following order, is 0.5 or higher and 1.1 or lower. [Testing order] (i) After setting the sealant for the display element to 23°C, a portion of the sealant for the display element is collected, and the sealant for the display element is applied to the SiN substrate by inkjet printing under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element was measured. The measurement result was set as D1. (ii) After transferring 9 g to 11 g of the sealant for the display element (set to 23°C in step (i)) into a 19 mL glass container, tighten the container cap. Refrigerate the container containing the sealant for the display element at 5°C for 7 days. (iii) The sealant for display elements collected from the refrigerated state in step (ii) is used to inkjet coat the SiN substrate with the sealant for display elements under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element was measured. The measurement result was set as D2. (iv) Calculate the drop diameter ratio R = D2 / D1 based on D1 and D2.

[0018] The sealant achieves a high level of preservation stability by including the aforementioned structure. The following is a detailed description of the sealant. (Drop diameter ratio R) The drop size ratio R is determined by the [determination sequence] comprising steps (i) to (iv). The steps (i) to (iv) are described in detail below.

[0019] Step (i) First, after setting the prepared sealant for the display element to 23°C, collect a portion of the sealant and place it in the inkjet unit. For example, introduce the sealant into an inkjet cartridge and place the cartridge in the inkjet unit. Heat the inkjet cartridge to a temperature of, for example, 35°C. There is no limit to the holding time after introducing the sealant into the inkjet cartridge, but it is preferably set to 1 minute to 24 hours.

[0020] Subsequently, an inkjet cartridge containing a sealant for display elements is placed in an inkjet printer, and the sealant for display elements is applied to the SiN substrate by inkjet printing under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃

[0021] As an inkjet cartridge, for example, the DMC-11610 (manufactured by Fuji Film Dimatix) can be used; as an inkjet unit, for example, the DMP-2831 (manufactured by Fuji Film Dimatix) can be used. After inkjet coating, the diameter of the sealant droplet on the display element is measured after 180 seconds. The diameter can be, for example, the average of the maximum and minimum diameters. The measurement result is set as D1.

[0022] Step (ii) Add 9-11 g of the prepared sealant for the display element to a 19 mL glass container and tighten the lid. Refrigerate the container containing the sealant at 5°C for 7 days. Securely tighten the lid with a spacer tape. Maintain atmospheric pressure above the interior of the container.

[0023] Step (iii) The refrigerated display element is then introduced into the inkjet cartridge at room temperature using a sealant and kept at 23°C. It is preferable that the sealant applied to the display element before heat preservation temporarily restores the temperature to 23°C. There is no limit to the heat preservation time after introduction into the inkjet cartridge, but it is preferably set to 1 minute to 24 hours. Subsequently, an inkjet cartridge containing a sealant for display elements is placed in an inkjet printer, and the sealant for display elements is applied to the SiN substrate by inkjet printing under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element is measured. The diameter can be, for example, the average of the maximum and minimum diameters. The measurement result is set as D2.

[0024] Step (iv) (iv) Calculate the drop diameter ratio R = D2 / D1 based on D1 and D2.

[0025] The lower limit of the drop size ratio R is 0.5 or higher, preferably 0.7 or higher, and even more preferably 0.9 or higher. Furthermore, the upper limit of the drop size ratio R is 1.1 or lower, preferably 1.0 or lower. By setting the droplet diameter ratio R within this range, a high level of preservation stability can be achieved in sealants containing leveling agents. Furthermore, in existing sealants for display elements containing leveling agents, the droplet diameter ratio R is typically a value of 2.6 or higher.

[0026] (Manufacturing considerations) To obtain a sealant with a drop size ratio R within the range described, the following considerations should be taken into account during the manufacturing process. The sealant is prepared by mixing (A) a cationic polymerizable compound, (B) a cationic polymerization initiator, (C) a leveling agent, and a suitable solvent or other additive. Prior to this mixing, it is preferable to apply ultrasonic vibration to (A) the cationic polymerizable compound and the solvent, and to perform nitrogen foaming to remove dissolved oxygen. Furthermore, after mixing, it is also preferable to perform nitrogen foaming to remove dissolved oxygen. Performing such operations is effective, for example, as a process for achieving the drop size ratio R within the range described.

[0027] Next, specific examples will be given to illustrate the composition of sealants. (ingredient (A)) Component (A) is a cationic polymerizable compound. A cationic polymerizable compound is a compound that can be cationicly polymerized by light or heat, and is a compound having one or more groups selected from epoxy groups, groups containing oxobutane rings, vinyl ether groups, and cyclic sulfide groups within its molecule.

[0028] From the viewpoint of improving the strength of the hardened material, the content of component (A) in the sealant is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, and even more preferably 90% by mass or more, relative to all components of the sealant.

[0029] In addition, from the viewpoint of improving the weather resistance of the sealing material, the content of component (A) in the sealant is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99% by mass or less, relative to all the components of the sealant.

[0030] From the viewpoint of improving the weather resistance of sealing materials, component (A) preferably contains one or both of an epoxy compound and an oxetane compound. The total content of the epoxy compound and the oxetane compound is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Component (A) may contain one or both of an epoxy compound and an oxetane compound.

[0031] (Epoxy compounds) Epoxy compounds are compounds that have one or more epoxy groups in one molecule. Specific examples include: monoepoxy compounds, difunctional epoxy compounds, and trifunctional or higher epoxy compounds. Examples of epoxy compounds include EP1 to EP3.

[0032] ･EP1 EP1 is an alicyclic epoxy compound, which is a compound having at least one epoxycycloalkyl or epoxycycloalkenyl group in the molecule, or a compound having at least one group in the molecule that is formed by at least one epoxy group bonded to the alicyclic ring by a single bond.

[0033] ･EP2 EP2 includes bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallyl bisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide addition bisphenol A type epoxy compounds, and other bisphenol type epoxy compounds.

[0034] ･EP3 EP3 refers to epoxy compounds other than EP1 and EP2, including: resorcinol-type epoxy compounds, biphenyl-type epoxy compounds, thioether-type epoxy compounds, diphenyl ether-type epoxy compounds, dicyclopentadiene-type epoxy compounds, naphthalene-type epoxy compounds, phenolic varnish-type epoxy compounds, o-cresolic varnish-type epoxy compounds, dicyclopentadieneic varnish-type epoxy compounds, biphenylic varnish-type epoxy compounds, naphtholic phenolic varnish-type epoxy compounds, glycidylamine-type epoxy compounds, alkyl polyol-type epoxy compounds, rubber-modified epoxy compounds, glycidyl ester compounds, etc. From the viewpoint of improving the weather resistance of sealing materials, epoxy compounds are preferably alicyclic epoxy compounds (the EP1).

[0035] Alicyclic epoxy compounds are any compounds whose molecules contain one or more alicyclic hydrocarbon structures and epoxy groups, respectively. Alicyclic epoxy compounds may have one or more epoxy groups within their molecules; from the viewpoint of improving the curing properties of sealants, having two or more epoxy groups is preferred.

[0036] Examples of alicyclic epoxy compounds include compounds containing cycloolefin oxide structures such as cyclohexane oxide, and compounds in which epoxy groups are directly or indirectly bonded to cyclic aliphatic hydrocarbons via hydrocarbon groups. From the viewpoint of improving the curing properties of sealants, alicyclic epoxy compounds are preferably compounds having cycloolefin oxide structures.

[0037] Here, the so-called cyclic olefin oxide structure refers to the structure obtained by epoxidizing cyclic olefins using oxidants such as peroxides, and is composed of an epoxy group consisting of two adjacent carbon atoms and an oxygen atom forming an aliphatic ring. Cyclic olefin oxides are, for example, cyclohexene oxide and cyclopentene oxide, with cyclohexene oxide being preferred.

[0038] A molecule of an alicyclic epoxide compound with a cyclic olefin oxide structure can contain one or more cyclic olefin oxide structures. From the perspective of improving the transparency, heat resistance, lightfastness, etc., of the cured product, it is preferable that a molecule contains two or more cyclic olefin oxide structures. As alicyclic epoxide compounds having a cyclic olefin oxide structure, compounds represented by the following general formula (1) can be listed as examples.

[0039] [Chemistry 1]

[0040] In general formula (1), X is a single bond or a divalent linking group. The linking group may be selected from, for example, a divalent hydrocarbon group, a carbonyl group, an ether group (ether bond), a thioether group (thioether bond), an ester group (ester bond), a carbonate group (carbonate bond), and a amide group (amide bond), as well as a group formed by multiple links of these or a group containing these. Examples of divalent hydrocarbon groups include alkyl groups with 1 to 18 carbon atoms or divalent alicyclic hydrocarbon groups.

[0041] Specific examples of alkyl groups having 1 to 18 carbon atoms include: methylene, methylmethylene, dimethylmethylene, ethyl alkyl, propyl alkyl, and trimethylene.

[0042] In addition, specific examples of divalent alicyclic hydrocarbon groups include: 1,2-epoxycyclopentyl, 1,3-epoxycyclopentyl, cyclopentylene, 1,2-epoxycyclohexyl, 1,3-epoxycyclohexyl, 1,4-epoxycyclohexyl, cyclohexylene, and other divalent cycloalkyl groups (including cycloalkylene groups). From the perspective of improving hardening properties, X is preferably a single bond or a linker group with an oxygen atom, and more preferably a single bond.

[0043] From the same point of view, the linking group having an oxygen atom is preferably -CO- (carbonyl), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (acetamino group), a group formed by linking multiple of these groups, or a group formed by linking one or more of these groups with one or more divalent hydrocarbon groups. The following are specific examples of alicyclic epoxides represented by general formula (1).

[0044] [Chemistry 2]

[0045] [Chemistry 3]

[0046] In the formula, l represents an integer from 1 to 10, and m represents an integer from 1 to 30. R represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms such as methylene, ethyl, propyl, or isopropyl. Additionally, n1 and n2 each independently represent an integer from 1 to 30.

[0047] Specific examples of commercially available alicyclic epoxides having a cyclic olefin oxide structure include: Celloxide (CEL) 2021P, Celloxide 2000, Celloxide 2081, Celloxide 3000, Celloxide 8000, and Celloxide 8010 (all manufactured by Daicel).

[0048] In addition, as other preferred examples of epoxy compounds, aliphatic epoxy compounds, such as 1,6-hexanediol diglycidyl ether (e.g., Epigose HD(D), manufactured by Yokkaichi Synthetic Co., Ltd.) and neopentyl glycol diglycidyl ether (e.g., SR-NPG, manufactured by Sakamoto Pharmaceutical Co., Ltd.), can be cited. From the perspective of improving the curability of sealing materials, epoxy resins are preferably those containing alicyclic epoxy compounds and aliphatic epoxy compounds.

[0049] From the viewpoint of improving curability, the content of epoxy compound in the sealant is preferably 20% by mass or more, more preferably 30% by mass or more, and more preferably 40% by mass or more, relative to all components of the sealant.

[0050] In addition, from the viewpoint of improving the flexibility or adhesion of the hardened material, the content of epoxy compound in the sealant is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 60% by mass or less, and further preferably 50% by mass or less, relative to all components of the sealant.

[0051] (Oxycyclic butane compounds) Oxycyclic butane compounds are compounds that have one or more oxycyclic butyl groups in one molecule. Specific examples include: monooxycyclic butane compounds, difunctional oxycyclic butane compounds, and trifunctional or higher oxycyclic butane compounds.

[0052] From the viewpoint of improving the hardening properties of sealing materials, the oxobutane compound may be selected as one or more compounds from the group consisting of the following general formulas (2) and (3).

[0053] [Chemistry 4]

[0054] [Chemistry 5]

[0055] In general formulas (2) and (3), Y represents an oxygen atom, a sulfur atom, or a single bond. From the viewpoint of improving the weather resistance of sealing materials, Y is preferably an oxygen atom.

[0056] In general formula (2), R 1a and in general formula (3) represent fluorine atom, alkyl with 1 to 6 carbon atoms, fluoroalkyl with 1 to 6 carbon atoms, allyl, aryl with 6 to 18 carbon atoms, furanyl or ethynyl, respectively.

[0057] In addition, s in general formula (2) and t in general formula (3) represent integers greater than 1 and less than 5, respectively. When a molecule contains multiple R 1a or R 1b, these can be the same or different. Furthermore, adjacent R 1a or adjacent R 1b can form a ring structure with each other.

[0058] In addition, in general formula (2), R 2a represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkyl carbonyl group having 2 to 6 carbon atoms, an alkoxy carbonyl group having 2 to 6 carbon atoms, an N-alkylaminomethyl group having 2 to 6 carbon atoms, or a (meth)acrylic acid group.

[0059] On the other hand, in general formula (3), R 2b represents a p-valent linking group. In general formula (3), p represents 2, 3 or 4, preferably 2. R 2b specifically represents oxygen, a straight-chain or branched alkyl group having 1 to 12 carbon atoms, a straight-chain or branched poly(alkyloxy) group, an aryl group, a siloxane bond, or a combination thereof.

[0060] (Difunctional oxoheterocyclic butane compounds) From the viewpoint of improving the curing properties of the sealant, the oxetane compound is preferably a difunctional oxetane compound represented by the following general formula (5) or general formula (6).

[0061] [Chemistry 6]

[0062] In general formulas (5) and (6), R5 represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, an allyl group, an aryl group, an aralkyl group, a furanyl group, or a thiophene group. R6 represents a divalent organic residue.

[0063] Examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, and cyclohexyl. Examples of aryl groups include phenyl, naphthyl, tolyl, and xylyl. Examples of aralkyl groups include benzyl and phenethyl. Examples of divalent organic residues include alkylene, polyoxyalkylene, phenylene, xylene, and structures represented by the following formula.

[0064] [Chemistry 7]

[0065] In the formula, R3 is an oxygen atom, a sulfur atom, -CH2-, -NH-, -SO-, -SO2-, -C(CF3)2-, or -C(CH3)2-. R 4 is an alkyl or aryl group having 1 to 6 carbon atoms. Examples of alkyl groups include methylene, ethyl, propyl, butyl, and cyclohexyl groups having 1 to 15 carbon atoms. Polyoxyalkyl groups are preferably polyoxyalkyl groups having 4 to 30 carbon atoms, more preferably 4 to 8 carbon atoms, and examples include polyoxyethyl and polyoxypropyl groups.

[0066] From the viewpoint of improving the curing properties of the sealant, oxetane compounds are preferably those represented by general formula (6). Examples of compounds represented by general formula (6) include 3-ethyl-3-{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane, and commercially available examples include Aron Oxetane OXT-221 (manufactured by Toa Synthetic Co., Ltd.).

[0067] (Monofunctional oxoheterocyclic butane compounds) From the viewpoint of improving the curing properties of the sealant, oxobutane compounds are also preferably compounds represented by the following general formula (4).

[0068] [Chemistry 8]

[0069] In general formula (4), Y is an oxygen atom or a sulfur atom. From the viewpoint of improving the weather resistance of the sealing material, Y is preferably an oxygen atom. R1c represents a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, a furanyl group, or a thiophene group. From the viewpoint of improving the curing properties of the cured sealant, R1c is preferably an alkyl group having 1 to 6 carbon atoms.

[0070] R 2c is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, an alkyl carbonyl group having 2 to 6 carbon atoms, an alkoxy carbonyl group having 2 to 6 carbon atoms, an N-alkylaminomethyl group having 2 to 6 carbon atoms, or a (meth)acrylic acid group. From the viewpoint of improving the curing properties of the cured sealant, R 2c is preferably an alkyl group having 1 to 10 carbon atoms.

[0071] Specific examples of compounds represented by general formula (4) include: 3-ethyl-3-hydroxymethyloxetane, 3-(methyl)allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetane-butylmethoxy)methylbenzene, 4-fluoro-[1-(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, 4-methoxy-[1-(3-ethyl-3-oxetane-butylmethoxy)methyl]benzene, [1-(3-ethyl-3-oxetane-butylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl 3-Ethyl-3-oxetane(3-ethyl ...

[0072] From the viewpoint of improving the curing properties of the sealant, the content of the oxetane compound in the sealant is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, and even more preferably 50% by mass or more, relative to all components of the sealant. Furthermore, from the viewpoint of improving the viscosity of the sealant, the content of the oxetane compound in the sealant is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, relative to all components of the sealant.

[0073] (Ingredient (B)) Component (B) is a cationic polymerization initiator. Specific examples of cationic polymerization initiators include one or more selected from the group consisting of photoradical initiators and thermal polymerization initiators. From the viewpoint of stably forming a hardened product at low temperatures, component (B) is preferably a photocationic polymerization initiator that generates free radicals or ions by irradiation with light such as ultraviolet light (UV) (ultraviolet (UV) radical initiator, UV cationic initiator). A photocationic polymerization initiator is simply a compound that can generate cationic species and initiate the polymerization of component (A) by means of light such as light irradiation.

[0074] Specific examples of photocationic polymerization initiators include salts of onium ions (onium salts) represented by the following general formula (7). These onium salts release Lewis acids via photoreaction. [R 12 aR 13 bR 14 cR 15 dW] v+[MX v+u] u-(7)

[0075] In general formula (7), W represents S, Se, Te, P, As, Sb, Bi, O, I, Br, Cl, or N≡N. R12, R13, R14, and R15 each independently represent an organic group, and a, b, c, and d each independently represent an integer from 0 to 3. Furthermore, "a+b+c+d" has the same valence as W.

[0076] In addition, in general formula (7), M represents the metal or metalloid that forms the central atom of the halide complex [MX v+u]. Specific examples of M include: B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, and Co. In general formula (7), X represents halogen atoms such as F, Cl, and Br, u represents the net charge of the halide complex ion, and v represents the valence of M.

[0077] Specific examples of onium ions in general formula (7) include: diphenyl monazine, bis(4-methoxyphenyl)monazine, 4-methylphenyl-4'-isopropylphenyl monazine, bis(4-methylphenyl)monazine, bis(4-tert-butylphenyl)monazine, bis(dodecylphenyl)monazine, tolylcumyl monazine, triphenyl strontium, diphenyl-4-thiophenoxyphenyl strontium, bis[4-(diphenylstrontium)-phenyl] sulfide, bis[4-(di(4-(2-hydroxyethyl)phenyl)strontium)-phenyl] sulfide, and n5-2,4-(cyclopentadienyl)[1,2,3,4,5,6-n-(methylethyl)benzene]-iron(1+).

[0078] In addition, specific examples of anions in general formula (7) include: tetrafluoroborate, tetra(pentafluorophenyl)borate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, and hexachloroantimonate.

[0079] In terms of superior safety for organisms, the anion in general formula (7) is preferably selected from the group consisting of tetrafluoroborate, tetra(pentafluorophenyl)borate and hexafluorophosphate.

[0080] Examples of commercially available photocationic polymerization initiators represented by general formula (7) include: Irgacure 250, Irgacure 270, Irgacure 290 (manufactured by BASF), CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG (manufactured by San-Apro), SP-150, SP-170, SP-171, SP-056, SP-066, SP-130, SP-140, SP-601, SP-606, SP-701 (manufactured by ADEKA), PI-2074 (trade name, manufactured by Rhodia), etc. From the viewpoint of improving hardening properties, the photocationic initiator represented by general formula (7) is preferably one or more selected from the group consisting of Irgacure 270, Irgacure 290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG, SP-150, SP-170, SP-171, SP-056, SP-066, SP-601, SP-606, SP-701 and PI-2074.

[0081] From the viewpoint of improving hardening properties, the content of component (B) in the sealant is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, relative to all components of the sealant.

[0082] In addition, from the viewpoint of suppressing the coloring of the sealant, the content of component (B) in the sealant is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less, relative to all the components of the sealant.

[0083] (Ingredient (C)) Component (C) is a leveling agent. A leveling agent is an additive used to facilitate the wetting and diffusion of a sealant applied by inkjet printing onto the surface of the object being coated. The leveling agent functions to improve the flowability and defoaming properties of the sealant and to enhance the smoothness of the resulting sealant film. Examples of leveling agents include fluorinated, acrylic, and silicone polymers. Among these, to minimize surface-modifying effects, component (C) is preferably selected from one or more polymers chosen from the group consisting of silicone polymers and acrylate (acrylic) polymers.

[0084] Silicone-based polymers are preferably polymers having an intramolecular polymethylsiloxane or polydimethylsiloxane structure. The number of repetitions of the dimethylsiloxane is preferably 2 or more and 150 or less. Examples of silicone-based polymers include: polydimethylsiloxane, polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, polymethylalkylsiloxane, and aralkyl-modified polymethylalkylsiloxane.

[0085] Specifically, acrylic polymers are polymers containing structural units derived from alkyl (meth)acrylates, i.e., polymers containing monomers of alkyl (meth)acrylates. The alkyl chain of the alkyl (meth)acrylate preferably has 4 or more carbon atoms, more preferably 6 or more. The upper limit for the number of carbon atoms in the alkyl chain of the alkyl acrylate is, for example, 12. Examples of alkyl acrylates include: butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and copolymers of butyl acrylate and 2-ethylhexyl acrylate. Acrylate polymers are preferably free of fluorine atoms. There may be one or more alkyl (meth)acrylates.

[0086] As a leveling agent, examples include: BYK-310, BYK-310N, BYK-323, BYK-340, and BYK-350 are manufactured by BYK-Chemie Japan. Polyflow KL-100, Polyflow KL-700, Polyflow KL-850, and Polyflow No. 90, manufactured by Kyoei Chemical Co., Ltd. The F-552, F-553, F-554, F-556, F-557, and F-559 were manufactured by DIC. Viscoat 13F, manufactured by Osaka Organic Chemicals Co., Ltd., etc.

[0087] The weight-average molecular weight (Mw) of the polymer constituting the leveling agent is, for example, around 1,000 to 20,000, preferably 2,000 to 10,000. By setting the molecular weight below the upper limit, the seepage of the leveling agent from the hardened sealant can be suppressed. By setting the molecular weight above the lower limit, the sealant has good flowability and defoaming properties, and the smoothness of the formed sealant coating surface can be significantly improved. Here, the weight-average molecular weight (Mw) of the polymer constituting the leveling agent was determined by gel permeation chromatography (GPC) based on polystyrene standards.

[0088] The content of the leveling agent (C) relative to 100% by mass of component (A) is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. Furthermore, the content of the leveling agent (C) relative to 100% by mass of component (A) is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. By setting the content below the aforementioned lower limit, the sealant exhibits good flowability and defoaming properties, and the smoothness of the formed sealant coating surface is sufficiently improved. By setting the content above the aforementioned upper limit, the exudation of the leveling agent from the hardened sealant is suppressed.

[0089] In this embodiment, the sealant may also contain components other than components (A) to (C). Examples of components other than components (A) to (C) are given below. (Ingredient (D)) Component (D) is one or more compounds selected from the group consisting of benzotriazole compounds, triazine compounds, monophenol compounds, bisphenol compounds, triphenol compounds, phosphite compounds, and oxaphosphaphenanthrene oxide compounds. By including component (D) in the sealant, the weather resistance of the sealing material can be improved.

[0090] Specific examples of benzotriazole compounds include 2-(2-hydroxy-5-methylphenyl)benzotriazole. Other commercially available examples of benzotriazole compounds include: Tinuvin P, Tinuvin 234, Tinuvin 234FF, Tinuvin 326, Tinuvin 326FL, Tinuvin 329, Tinuvin 329FL, Tinuvin 360, Chimassorb 81, and Chimassorb (…). Chimassorb 81FL (manufactured by BASF), Kemesorb 71, Kemesorb 73, Kemesorb 74, Kemesorb 79, Kemesorb 279 (manufactured by Chemipro Chemicals), JF-77, JF-79, JF-80, JF-83, JF-832 (manufactured by Jōhoku Chemical Industry Co., Ltd.).

[0091] Specific examples of triazine compounds include: 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine and 2-hydroxyphenyl-triazine. Additionally, commercially available examples of triazine compounds include: Tinuvin 460, Tinuvin 1577ED, Tinuvin 1600 (manufactured by BASF), and Kemisorb 102 (manufactured by Chemipro Chemicals).

[0092] Specific examples of monophenol compounds include: phenylpropionic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 side-chain alkyl ester, and 2,6-di-tert-butyl-p-cresol. Additionally, specific examples of commercially available monophenol compounds include: Irganox 1135 (manufactured by BASF), KEMISORB 112, KEMISORB 113, KEMISORB 114, and KEMINOX 76 (manufactured by Chemipro Chemicals).

[0093] Specific examples of bisphenol compounds include 2,2-methylenebis(4-methyl-6-tert-butylphenol). Another example of a commercially available bisphenol compound is KEMINOX 9425 (manufactured by Chemipro Chemical Co., Ltd.). Specific examples of triphenol compounds include 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane.

[0094] From the viewpoint of improving the weather resistance of the sealing material, component (D) preferably contains one or more of the group consisting of benzotriazole compounds, triazine compounds and monophenol compounds, and more preferably contains one or two of these.

[0095] From the viewpoint of improving the weather resistance of sealing materials, the content of component (D) in the sealant is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.1% by mass or more, relative to all components of the sealant.

[0096] In addition, from the viewpoint of improving the hardening properties of the sealing material, the content of component (D) in the sealant is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to all the components of the sealant.

[0097] (Other ingredients) In this embodiment, the sealant may also contain other components besides those described, without impairing the effects of the invention. Examples of other components include adhesives, fillers, curing accelerators, plasticizers, surfactants, heat stabilizers, flame retardants, antistatic agents, defoamers, silane coupling agents, and ultraviolet absorbers.

[0098] By including a photosensitizer in the sealant, the curing properties of the sealant can be improved. Examples of photosensitizers include photocationic photosensitizers. From the perspective of wavelength-selective light sources such as ultraviolet-light emitting diodes (UV-LEDs), photosensitizers are preferably compounds that are excited by light with wavelengths of 350 nm to 450 nm. Specific examples of such photosensitizers include: polynuclear aromatic compounds such as pyrene, perylene, triphenylene oxide, and anthracene; and fluorescein, eosin, erythrosine, and rhodamine B. B) Oxanthracites such as Bengal rose red; oxanthraquinones such as oxanthraquinone, thioxanthraquinone, dimethylthioxanthraquinone, and diethylthioxanthraquinone; anthocyanins such as thioxanthraquinone and oxanthraquinone; anthocyanins such as thioxanthraquinone and oxanthraquinone; rhodacyanines; oxanthracyanides; thiocyanates; thiophene, methylene blue, and toluidine blue; acridine orange, chloroflavin, and acridine flavin; acridine ketones such as 10-butyl-2-chloroacridone; anthraquinones; squaric acid lactones; styrylyl groups; basic styrylyl groups; and coumarins such as 7-diethylamino-4-methylcoumarin. From the viewpoint of improving the hardening properties of sealing materials, photosensitizers are preferably polycyclic aromatic compounds, acridinones, coumarins, or basic styrene compounds, and more preferably anthracene compounds.

[0099] From the viewpoint of improving the curability of the sealant, the content of photosensitizer in the sealant is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, and preferably 3% by mass or less, more preferably 1.5% by mass or less, and even more preferably 1% by mass or less, relative to 100 parts by mass of component (A).

[0100] In addition, by including a coupling agent in the sealant, the adhesion between the sealing material and the sealed material can be further improved. Examples of coupling agents include silane coupling agents. From the viewpoint of improving the adhesion between the sealing material and the sealed material, silane coupling agents are preferably silane coupling agents having functional groups common to the polymerizable functional groups in component (A), or having functional groups capable of reacting with the polymerizable functional groups in component (A). For example, when component (A) contains an epoxy compound, the coupling agent is preferably one or more of the group consisting of silane coupling agents selected from those having epoxy groups and silane coupling agents having functional groups that react with epoxy groups (e.g., through an addition reaction).

[0101] Specific examples of silane coupling agents with epoxy groups include: γ-glycidoxypropyltrimethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0102] Specific examples of silane coupling agents having functional groups capable of reacting with epoxy groups include: silane coupling agents containing amino groups such as primary or secondary amino groups; carboxyl groups; methacrylic acid groups; isocyanate groups, etc.

[0103] Specific examples of these silane coupling agents include: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane or 3-(4-methylpiperidinyl)propyltrimethoxysilane, trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, and γ-isocyanopropyltriethoxysilane.

[0104] Alternatively, the coupling agent may also include coupling agents other than those mentioned above, such as other silane coupling agents. Examples of other silane coupling agents include vinyltriethoxysilane and vinyltrimethoxysilane. Furthermore, from the perspective of improving the adhesion between the sealing material and the sealed material, the molecular weight of the coupling agent is preferably 80 to 800.

[0105] From the viewpoint of improving the adhesion between the sealing material and the sealed material, the content of the coupling agent in the sealant is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, and also preferably 3% by mass or less, relative to 100 parts by mass of component (A).

[0106] Sealants may also contain polymerization inhibitors. Specific examples of polymerization inhibitors include: 2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-amino-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-partamide-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-acetamide-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-carboxyl-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), 4-methoxy-2,2,6,6-tetramethylpiperidin-1-oxy (free radical), and 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxy (free radical).

[0107] From the perspective of improving plasma resistance and suppressing damage to components using sealants, the content of polymerization inhibitor in the sealant is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.005% by mass or more, relative to all components of the sealant.

[0108] Furthermore, from the viewpoint of improving the hardening properties of the sealing material, the content of polymerization inhibitor in the sealant is preferably 1% by mass or less, more preferably 0.75% by mass or less, and even more preferably 0.5% by mass or less, relative to all components of the sealant.

[0109] From the perspective of improving the weather resistance of sealing materials and being suitable for forming hardened materials using coating methods such as inkjet printing, in this embodiment, the sealant is preferably solvent-free, or when the sealant contains a solvent, the solvent content is more than 0% by mass, preferably 0.05% by mass or less, and more preferably 0.03% by mass or less. As a specific example of a sealant that is solvent-free, examples of sealants in which the solvent is not intentionally incorporated during preparation can be cited.

[0110] Next, the characteristics of the sealant will be explained. From the perspective of improving the heat resistance of sealing materials, the glass transition temperature (Tg) of the cured sealant is above 40°C, preferably above 50°C, and even more preferably above 60°C. In addition, from the viewpoint of improving flexibility, the Tg of the hardened sealant is less than 200°C, preferably less than 190°C, and more preferably less than 180°C. Here, the glass transition temperature (Tg) is determined in the following order.

[0111] The cured sealant is obtained by using a 100 μm thick Teflon sheet (registered trademark) as a mold frame, sandwiching the uncured sealant between polyethylene terephthalate (PET) films, and then curing it using a 395 nm wavelength UV-LED under conditions of 1000 mW / cm² illuminance and 1500 mJ / cm² cumulative light intensity. Use a cutter to cut the hardened material into pieces 10 mm wide and 40 mm long.

[0112] Then, using a dynamic viscoelasticity measuring device "DMS6100" (manufactured by Seiko Instruments), while applying a frequency of 1 Hz to the cut hardened material in the atmosphere, the temperature was increased from room temperature to 250°C at 5°C / min, and tanδ was measured at the same time. The temperature of the peak of tanδ was set as the Tg of the hardened material.

[0113] In this embodiment, a sealant with a Tg within a specific range can be obtained, for example, by appropriately selecting the components and mixing ratios contained in the sealant and adjusting the manufacturing conditions.

[0114] There are no limitations on the properties of the sealant, but from the viewpoint of improving the flexibility and plasma resistance of the sealing material, and from the viewpoint of being suitable for forming hardened materials using coating methods such as inkjet printing, the sealant is preferably liquid.

[0115] In addition, from the viewpoint of stably forming a sealing material, the sealant is preferably used for coating, and more preferably for coating using inkjet printing.

[0116] From the viewpoint of improving inkjet ejection performance, the viscosity of the sealant, measured using an E-type viscometer at 25°C and 20 rpm, is preferably 5 mPa·s or higher, more preferably 8 mPa·s or higher, and even more preferably 10 mPa·s or higher. In addition, from the viewpoint of improving inkjet ejection performance, the viscosity of the sealant is preferably 80 mPa·s or less, more preferably 50 mPa·s or less, and even more preferably 30 mPa·s or less.

[0117] From the perspective of improving inkjet ejection performance, the thixotropic index (TI value) of the sealant is preferably 0.8 or higher, more preferably 0.9 or higher, and preferably 1.1 or lower, more preferably 1.0 or lower. Here, the TI value is obtained by measuring the viscosity at 5 rpm and 50 rpm using an E-type viscometer at 25°C and by the following formula. TI value = (viscosity at 5 rpm) ÷ (viscosity at 50 rpm)

[0118] From the viewpoint of improving the sealing properties of the sealant, the dielectric constant of the cured sealant is preferably 4.0 or less, more preferably 3.8 or less, and even more preferably 3.6 or less. In addition, the dielectric constant of the hardened sealant can be set to, for example, 1.0 or higher.

[0119] Here, the dielectric constant of the hardened sealant is the dielectric constant measured at a frequency of 100 kHz for the hardened material obtained by curing the curing component using a UV-LED with a wavelength of 395 nm under conditions of 1000 mW / cm2 illuminance and 1500 mJ / cm2 cumulative light intensity.

[0120] Next, the manufacturing method of the sealant will be explained. There is no limitation on the manufacturing method of the sealant. For example, it includes the operation of mixing components (A) to (C) and other suitable components, such as various additives added as needed. As a method for mixing the components, for example, the following methods can be listed: using alone or in combination with various known mixing machines such as planetary mixers, homogenizers, universal mixers, Banbury mixers, kneaders, two-rollers, three-rollers, extruders, etc., to uniformly mix under conditions such as room temperature or heating, normal pressure, reduced pressure, pressurized pressure, or inert gas flow.

[0121] Alternatively, the obtained sealant can be used to form a sealing material. For example, the sealant can be applied to a substrate and dried. Coating can be performed using known methods such as inkjet printing, screen printing, or dispenser coating. Drying can be carried out, for example, by heating to a temperature at which component (A) will not polymerize. The shape of the obtained sealing material is not limited; for example, it can be in the form of a film or a layer.

[0122] Furthermore, as described in the section on (manufacturing considerations), in order to obtain a sealant exhibiting a specific droplet diameter ratio R, the manufacturing process preferably involves, for example, applying ultrasonic vibration to (A) the cationic polymeric compound and the solvent, and performing nitrogen foaming to remove dissolved oxygen. Additionally, after mixing, it is also preferable to perform nitrogen foaming to remove dissolved oxygen. The sealing material is, for example, a hardened product formed by curing the sealant in this embodiment, and more specifically, a light-cured product of the sealant.

[0123] Methods for photocuring sealants include, for example, using light sources such as low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, excimer lasers, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, sodium lamps, halogen lamps, xenon lamps, LED lamps, fluorescent lamps, sunlight, and electron beam irradiation devices to irradiate and cure the sealant.

[0124] In this embodiment, since the sealant combination includes components (A) to (C) and the droplet diameter ratio R is within a specific range, a high level of preservation stability can be achieved by using the sealant.

[0125] Furthermore, the sealant obtained in this embodiment can be suitably used, for example, for sealing display elements, preferably organic EL display elements. According to this embodiment, a sealant achieving a high level of preservation stability can be obtained, thus improving the reliability of the sealing film and display device obtained by the sealant. Damage to the display element during the manufacturing process of the display device can be effectively suppressed, and the manufacturing stability of the display device can also be improved.

[0126] By using the hardened sealant obtained in this embodiment as a sealing material for, for example, display elements, preferably organic EL display elements, a display device with excellent weather resistance can be obtained. The following section uses an organic EL display device as an example to illustrate the structure of the display device.

[0127] (Organic EL display device) In this embodiment, the organic EL display device has a layer composed of a hardened sealant. Figure 1 is a cross-sectional view showing a structural example of the organic EL display device of this embodiment. The display device 100 shown in Figure 1 is an organic EL display device, including: a substrate (substrate layer 50); an organic EL element (light-emitting element 10) disposed on the substrate layer 50; and a sealing layer 22 (which may also be an outer coating layer 22 or a barrier layer 22) covering the light-emitting element 10. Moreover, for example, the sealing layer 22 contains a hardened form of the sealant of this embodiment.

[0128] Additionally, in Figure 1, the display device 100 includes a barrier layer 21 (which may also be a touch panel layer 21 or a surface protective layer 21), a sealing layer 22 (which may also be an outer coating layer 22 or a barrier layer 22), a planarization layer 23 (which may also be a sealing layer 23), and a barrier layer 24, which are located on the viewing side relative to the light-emitting element 10. The planarization layer 23 is disposed on the substrate layer 50 to cover the light-emitting element 10, and the barrier layer 24 is disposed on the surface of the planarization layer 23. The sealing layer 22 is disposed on the substrate layer 50 to cover the planarization layer 23 and the barrier layer 24. Furthermore, the barrier layer 21 is disposed on the sealing layer 22.

[0129] The specific structure of each layer is not limited, and appropriate structures can usually be adopted based on publicly known information. In addition, this display device 100 can usually be manufactured based on publicly known information. By using a resin layer obtained by hardening the sealant of this embodiment to protect the organic EL element, moisture can be effectively prevented from penetrating into the organic EL element, thereby maintaining the high performance and durability of the organic EL element. Organic EL display devices can be either top-emitting or bottom-emitting structures. The organic EL element is preferably disposed on a substrate and pre-coated with an inorganic material film in a manner that covers the area containing the organic EL element before being protected by a resin layer obtained by curing the sealant in this embodiment.

[0130] The material of the substrate layer 50 is not limited; for example, various materials such as glass substrates, silicon substrates, and plastic substrates can be used. TFT substrates that include multiple thin-film transistors (TFTs) and planarization layers on the substrate can also be used.

[0131] Inorganic materials constituting the barrier layer 24, i.e., the inorganic material film, can be exemplified by silicon nitride (SiNx), silicon oxide (SiOx), aluminum oxide (Al₂O₃), etc. The inorganic material film can be a single layer or a multi-layered laminate.

[0132] Regarding methods for coating the light-emitting element 10 with an inorganic material film, for example, when the inorganic material film contains silicon nitride or silicon oxide, sputtering or electron cyclotron resonance (ECR) plasma chemical vapor deposition (CVD) methods can be cited.

[0133] Sputtering, for example, can use argon or nitrogen, alone or in mixtures, as the carrier gas, and be carried out at room temperature, with an electricity of 50 W to 1000 W and a pressure of 0.001 Torr to 0.1 Torr.

[0134] In addition, ECR plasma CVD can be carried out, for example, using a mixture of SiH4 and O2 or a mixture of SiH4 and N2, at a temperature of 30℃~100℃, a pressure of 10 mTorr~1 Torr, a frequency of 2.45 GHz, and a power of 10 W~1000 W.

[0135] As a method for protecting the light-emitting element 10 by using a resin layer, such as sealing layer 22, obtained by curing the sealant of this embodiment, methods such as applying sealant to the light-emitting element 10 and then curing it can be included. As a coating method, inkjet printing is preferred. The thickness of the resin layer is not limited, but from the viewpoint of improving sealing and flexibility, it is, for example, 0.1 μm to 50 μm, preferably 1 μm to 20 μm.

[0136] Furthermore, in the display device 100, in order to improve the effect of protecting the light-emitting element 10 from the influence of moisture or oxygen in the atmosphere, it is preferable to further deposit an inorganic material film (barrier layer 24) on the resin layer. The inorganic material or the method of forming the inorganic material film deposited on the resin layer is the same as the inorganic material film covering the light-emitting element 10.

[0137] The thickness of the inorganic material film formed on the resin layer is not limited, but from the viewpoint of improving sealing performance, it is, for example, 0.01 μm to 10 μm, preferably 0.1 μm to 5 μm.

[0138] In the display device 100, a barrier layer 24, a sealing layer 22, and another barrier layer 24 are sequentially disposed on the light-emitting element 10. Here, the sealing layer 22 comprises a resin layer obtained by curing the sealant of this embodiment, which has a high level of preservation, thereby obtaining a display device 100 with excellent reliability. Specifically, when performing the plasma processing step during the formation of the barrier layer 24 on the upper part of the sealing layer 22, damage to the barrier layer 24 can also be suppressed. In addition, the resin layer constituting the sealing layer 22 is itself difficult to deteriorate due to plasma processing, thus suppressing damage to the light-emitting element 10. Example

[0139] The present invention will now be described by way of examples and comparative examples, but the present invention is not limited to these examples and comparative examples. First, the materials used in the following examples are shown. (A) Cationic polymeric compounds) Polymerizable compound 1: Alicyclic epoxy compound (4,4'-bis(1,2-epoxycyclohexane)), CEL8010, manufactured by Daicel (the following formula is presumed to be a compound)

[0140] [Chemistry 9]

[0141] Polymerizable compound 2: Oxycyclic butane compound, 3-ethyl-3-{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane, OXT-221, manufactured by Toa Synthetic Co., Ltd. Polymerizable compound 3: Epoxy compound (glycidyl ether compound), 1,6-hexanediol diglycidyl ether, Epogose HD(D), manufactured by Yokkaichi Synthetic Co., Ltd.

[0142] (B) Cationic polymerization initiator) Polymerization Initiator 1: Photocationic Initiator, CPI-210S, manufactured by San-Apro.

[0143] (C) Leveling agent) Leveling agent 1: Polyester-modified polydimethylsiloxane, BYK-310N (manufactured by BYK-Chemie). Leveling agent 2: Aryl-modified polymethylalkylsiloxane, BYK-323 (manufactured by BYK-Chemie). Leveling agent 3: Reactive fluorinated leveling agent, Viscoat 13F (manufactured by Osaka Organic Chemicals Co., Ltd.) Leveling agent 4: Acrylic copolymer, BYK-350 (manufactured by BYK-Chemie). Leveling agent 5: Acrylic copolymer, Polyflow No. 90 (manufactured by Kyoei-sha). Leveling agent 6: A silicone-containing polymer, Polyflow KL-700 (manufactured by Kyoei-sha). Leveling agent 7: An oligomer containing fluorinated-lipophilic groups, F552 (manufactured by DIC). (Sensitizer) Sensitizer 1: Photocationic sensitizer (anthracite compound), UVS-1331 (manufactured by Kawasaki Chemical Industry Co., Ltd.)

[0144] (Examples 1-10, Comparative Example 1 and Comparative Example 2) The components were prepared in the manner shown in Table 1 to obtain a liquid, solvent-free composition, i.e., a sealant. Specifically, all components except the polymerization initiator listed in Table 1 were placed into a 19 mL glass container and mixed. After applying ultrasound to the glass container for 10 minutes, nitrogen foaming was performed at a rate of 0.1 mL / min. The amount of polymerization initiator shown in Table 1 was added to the obtained mixture, and then mixed. Subsequently, the mixture was stirred until no powder was visible, thus obtaining the sealant.

[0145] The physical properties of the sealants or their cured products obtained in each example were determined by the following methods. The results are shown in Table 1.

[0146] (Drop diameter ratio R) The drop size ratio R is determined by the following steps (i) to (iv). The sealant obtained in each example is manufactured, and the determination begins within 3 hours. Step (i) After setting the sealant obtained in each example to 23°C, a portion of the sealant for the display element was collected and introduced into the inkjet cartridge (DMC-11610, manufactured by Fuji Film Dimatix). After introduction, the temperature of the sealant was set to 35°C by heating the cartridge. This temperature was maintained for 10 minutes. Subsequently, an inkjet cartridge containing sealant was placed in an inkjet printer (DMP-2831, manufactured by Fuji Film Dimatix), and sealant was applied to the SiN substrate by inkjet printing under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After the sealant was applied by inkjet printing, the diameter of the droplet was measured after 180 seconds. The average of the maximum and minimum diameters was taken as D1.

[0147] Step (ii) After the display element, which was set to 23°C in step (i), is introduced into a 19 mL glass container with 9 g to 11 g of sealant, the container lid is tightly tightened with a spacer seal and refrigerated at 5°C for 7 days. The upper space inside the container is kept atmospheric.

[0148] Step (iii) Temporarily restore the sealant, which was refrigerated in step (ii), to 23°C, and import it into the inkjet cartridge. Keep it at 35°C for 10 minutes. Subsequently, an inkjet cartridge containing sealant is placed in an inkjet printer, and the sealant is applied to the SiN substrate by inkjet printing under the following conditions. (a) Ejection volume: 7 picoliters (b) Temperature of SiN substrate and ambient temperature: 23℃ After 180 seconds, the diameter of the sealant droplet on the display element was measured. The average of the maximum and minimum diameters was taken as D2. Step (iv) (iv) Calculate the drop diameter ratio R = D2 / D1 based on D1 and D2.

[0149] (Viscosity Measurement) The viscosity of the hardened components obtained in each example was determined using an E-type viscometer (LV DV-II+ Pro, manufactured by BROOKFIELD) at 25°C and 20 rpm.

[0150] (Thixotropy) Thixotropy (TI value) is determined by measuring the viscosity at 5 rpm and 50 rpm at 25°C using the same measuring instrument as viscosity measurement, and then using the following formula. TI value = (viscosity at 5 rpm) ÷ (viscosity at 50 rpm)

[0151] (Evaluation Method) (Inkjet coating characteristics) The inkjet ejection performance was evaluated based on the inkjet coating characteristics shown in steps (i) and (iii) of the method for determining the droplet diameter R. A DMP-2831 inkjet ejection device, manufactured by Fuji Film Dimatix, was used, and inkjet coating was performed at a head temperature of 35°C and an applied voltage of 35 V. The evaluation criteria are shown below. OK: When the inkjet head is heated to 35°C and ejected, coating can be stably performed by the inkjet device. NG: When the inkjet head is heated to 35°C and ink is ejected, a mist is produced during ink ejection, or no ink is ejected at all.

[0152] (End retention) (Preparation of the evaluation sample) Regarding the end-retention evaluation specimens, the laminates used as evaluation specimens were formed in the following order: The sealant obtained in each example was introduced into an inkjet cartridge DMC-11610 (manufactured by Fuji Film Dimatix). The inkjet cartridge was placed in an inkjet unit DMP-2831 (manufactured by Fuji Film Dimatix), and after adjusting the ejection state, it was coated on alkali-free glass with a hardened thickness of 10 μm and dimensions of 20 mm wide × 20 mm long. The obtained coating was then subjected to nitrogen rinsing for 3 minutes and placed at room temperature (25°C), followed by curing using a 395 nm wavelength UV-LED with an illuminance of 1000 mW / cm² and a cumulative light intensity of 1500 mJ / cm².

[0153] (Observation of the sample) The coating width of the obtained coating film was measured at 3 points in each direction using an Alpha-Step D-600 stylus profilometer (manufactured by Ulvac), and the average value was calculated. The coating was then evaluated according to the following criteria. NG: Coating width ≥ 20.50 mm OK: Coating width less than 20.50 mm

[0154] [Table 1] Table 1 Example Comparative example 1 2 3 4 5 6 7 8 9 10 1 2 composition (parts by weight) Polymer compound 1 Alicyclic epoxides 40 40 40 40 40 30 30 30 20 20 40 20 Polymer compound 2 oxacyclobutane compounds 60 60 60 60 60 55 55 55 55 55 60 55 Polymer compound 3 glycidyl ether compounds 15 15 15 25 25 25 Polymerization initiator 1 Photocation initiator 1 1 1 1 1 1 1 1 1 1 1 1 Senser 1 Photocation sensitizer 1 1 1 1 1 1 1 1 1 1 1 1 Leveling agent 1 Polyester-modified polydimethylsiloxane 0.3 0.3 Leveling agent 2 Aryl-modified polymethylalkylsiloxane 0.3 0.3 Leveling agent 3 Reactive fluorinated leveling agent 0.3 Leveling agent 4 Acrylic copolymers 0.3 0.3 Leveling agent 5 Acrylic copolymers 0.3 0.3 Leveling agent 6 Polymers containing silicone 0.3 Leveling agent 7 Oligomers containing fluorinated-lipophilic groups 0.3 0.3 viscosity 20 rpm 21.5 21.6 21.5 21.4 21.7 17.5 17.6 17.5 15 14.9 21.5 15 Thixotropy 5 rpm / 50 rpm 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Drop diameter 7 pL, SiN substrate Leveling for 180 seconds After D1 is mixed 157 150 153 143 148 160 157 150 153 145 350 145 D2 After refrigerating at 5℃ for 7 days 150 149 146 145 146 149 145 151 153 145 388 388 Droplet diameter ratio R 0.96 0.99 0.95 1.01 0.99 0.93 0.92 1.01 1.00 1.00 1.11 2.68 Inkjet ejection properties Head temperature 35℃ Apply voltage 35 V After mixing OK OK OK OK OK OK OK OK OK OK NG OK After refrigerating at 5℃ for 7 days OK OK OK OK OK OK OK OK OK OK NG NG End retention determination OK OK OK OK OK OK OK OK OK OK NG OK Coating width (mm) 20.18 20.08 20.10 20.12 20.13 20.09 20.1 20.13 20.10 20.09 20.8 20.10

[0155] *The viscosity units in Table 1 are mPa·sec (millipascal second). *The unit for Drop diameter in Table 1 is μm (micron).

[0156] According to Table 1, the sealants obtained in each embodiment exhibit high levels of preservation stability and high end retention due to the presence of a leveling agent and a drop diameter ratio R within a specific range. Therefore, by using the sealants in each embodiment for sealing organic EL display elements, an organic EL display device with excellent reliability can be obtained.

[0157] This application claims priority based on Japanese Patent Application No. 2021-080497, filed on May 11, 2021, and all disclosures thereof are incorporated herein by reference.

[0158] 10: Light-emitting element 21: Barrier layer, touch panel layer, or surface protective layer 22: Sealing layer, outer coating, or barrier layer 23: Planarization layer or sealing layer 24: Barrier layer 50: Substrate layer 100: Display device

Claims

1. A sealant for display elements, comprising the following components (A) to (C): (A) a cationic polymerizable compound, (B) a cationic polymerization initiator, and (C) a leveling agent, wherein the droplet diameter ratio R of the sealant for display elements, measured in the following order, is 0.5 or more and 1.1 or less, wherein component (A) comprises an epoxy compound, and the epoxy compound comprises an alicyclic epoxy compound, [Measurement order] (i) After setting the sealant for display elements to 23°C, a portion of the sealant for display elements is collected and inkjet coated onto a SiN substrate under the following conditions: (a) Ejection volume: 7 picoliters (b) Temperature of the SiN substrate and ambient temperature: 23°C After landing, the diameter of the landing droplet of the sealant for display elements is measured after 180 seconds; the measurement result is set as D1; ​​(ii) 9 g to 11 g of the sealant for display elements set to 23°C in step (i) is used. After g is introduced into a 19 mL glass container, the container cap is tightened; the container containing the sealant for the display element is refrigerated at 5°C for 7 days; (iii) the sealant for the display element after refrigeration in step (ii) is collected and inkjet coated onto a SiN substrate under the following conditions: (a) spray volume: 7 picoliters (b) temperature of SiN substrate and ambient temperature: 23°C After landing, the diameter of the droplet of the sealant for the display element is measured after 180 seconds; the measurement result is set as D2; (iv) the droplet diameter ratio R = D2 / D1 is calculated based on D1 and D2.

2. The sealant for display elements as claimed in claim 1, wherein the component (A) further comprises one or both of an aliphatic epoxy compound and an oxetane compound.

3. The sealant for display elements as claimed in claim 1 or claim 2, wherein the component (C) is one or more selected from the group consisting of silicone polymers and acrylate polymers.

4. The sealant for display elements as claimed in claim 1 or claim 2, wherein the component (C) is a silicone polymer having an intramolecular polymethylsiloxane structure or a polydimethylsiloxane structure.

5. A sealant for a display element as claimed in claim 1 or claim 2, wherein the component (C) is a polymer comprising structural units derived from alkyl (meth)acrylates.

6. The sealant for a display element as claimed in claim 1 or claim 2, wherein the content of said component (C) is 0.01% by mass or more and 5% by mass or less relative to 100% by mass of said component (A).

7. The sealant for display elements as claimed in claim 1 or claim 2, wherein the component (B) is a photocationic polymerization initiator of a cationic species that generates polymerization by light.

8. The sealant for display elements as claimed in claim 1 or claim 2, wherein the viscosity at 25°C and 20 rpm, as measured by a type E viscometer, is 5 mPa·s or more and 80 mPa·s or less.

9. A sealant for display elements as described in claim 1 or claim 2, used for sealing organic electroluminescent display elements.

10. A hardened material formed by hardening a display element as described in any one of claims 1 to 9 with a sealant.

11. A display device, comprising: substrate; A display element is disposed on the substrate; And a sealing layer covering the display element, and the sealing layer comprising a hardened form of a sealant for a display element as described in any one of claims 1 to 9.

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