Photosensitive composition, cured product, organic electroluminescent display device, and method for producing photosensitive composition

Abstract

A photosensitive composition comprising a polymerizable compound and a photopolymerization initiator. The water concentration in the composition is 1 ppm or more and 50 ppm or less. In addition, when the toluene concentration in the composition is a and the toluene concentration in the cured film when the composition is made into a cured film is b, a-b is 50 ppm or less. The photosensitive composition is preferably used for sealing an organic electroluminescent element.

Description

Technical Field

[0001] The present invention relates to, for example, a photosensitive composition, a cured product, an organic electroluminescent display device, and a method for producing the photosensitive composition.

[0002] More specifically, the present invention relates to a photosensitive composition, a cured product thereof, an organic electroluminescent display device in which an organic electroluminescent element is sealed using the cured product thereof, and a method for producing a photosensitive composition for sealing an organic electroluminescent element. Background Art

[0003] Organic electroluminescent elements (hereinafter also referred to as organic EL elements) have attracted much attention as elements capable of emitting light with high brightness. However, organic EL elements have the problem of degradation due to oxygen and moisture, and reduced luminescence characteristics. In order to solve this problem, a technology for sealing organic EL elements to prevent degradation has been studied.

[0004] Patent document 1 describes a sealant for an organic EL display element, which contains a polymerizable compound and a polymerization initiator, and has a viscosity of 5 to 50 mPa·s at 25°C, a surface tension of 15 to 35 mN / m at 25°C, and a water content of less than 1000 ppm at 25°C after standing for 24 hours under environmental conditions of 25°C and 50% RH.

[0005] Patent Document 2 describes a resin composition suitable for a sealing material of an organic EL element, which contains a (meth)acrylate compound (A) having an aromatic hydrocarbon skeleton, a cyclic (meth)acrylate compound (B), and a polymerization initiator (C). Here, the cyclic (meth)acrylate compound (B) is at least one (meth)acrylate compound selected from (meth)acrylate compounds different from compound (A), i.e., (meth)acrylate compounds having an aromatic hydrocarbon skeleton, (meth)acrylate compounds having an alicyclic hydrocarbon skeleton, and (meth)acrylate compounds having a heterocyclic skeleton.

[0006] Patent Document 3 describes a sealant for an organic electroluminescent display element, which contains (A) an alkanediol di(meth)acrylate having 4 to 20 carbon atoms and (B) a photopolymerization initiator, wherein the amount of hydrophilic functional groups per (meth)acrylate is in the range of 4.80 to 7.60 mmol / g.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2019-040872

[0010] Patent Document 2: Japanese Patent Application Publication No. 2014-193970

[0011] Patent Document 3: International Publication No. 2019 / 203071 Summary of the invention

[0012] Problems to be solved by the invention

[0013] As described above, various compositions for sealing organic EL elements have been proposed so far. However, according to the findings of the present inventors, there is still room for improvement in compositions for sealing organic EL elements.

[0014] For example, a composition for sealing an organic EL element is preferably easy to handle industrially.

[0015] In addition, it is preferred to improve the reliability of the organic EL element by improving the composition for sealing the organic EL element.

[0016] The present invention has been made in view of the above circumstances. An object of the present invention is to provide a composition for sealing an organic EL element which is easy to handle industrially and can improve the reliability of the organic EL element.

[0017] Means for solving problems

[0018] The present inventors have completed the invention provided below and solved the above-mentioned problems.

[0019] According to the present invention, there is provided a photosensitive composition comprising a polymerizable compound photopolymerization initiator,

[0020] The water concentration in the composition is 1 ppm or more and 50 ppm or less.

[0021] When the toluene concentration in the composition is set to a,

[0022] The composition was irradiated with 1500 mJ / cm 2 When the toluene concentration in the cured film obtained by emitting light of 395 nm wavelength from an LED lamp is set to b,

[0023] ab is 50 ppm or less.

[0024] Furthermore, according to the present invention, a cured product of the above-mentioned photosensitive composition is provided.

[0025] Furthermore, according to the present invention, there is provided an organic electroluminescent display device in which an organic electroluminescent element is sealed with the above-mentioned cured product.

[0026] In addition, according to the present invention, there is provided a method for producing a photosensitive composition, which is the method for producing the above-mentioned photosensitive composition.

[0027] The production method includes a step of de-volatilizing the polymerizable compound at a pressure of 10 to 100° C. to 1000 Pa or less for 10 minutes or more.

[0028] Effects of the Invention

[0029] According to the present invention, there is provided a composition for sealing an organic EL element which is easy to handle industrially and can improve the reliability of the organic EL element. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described in detail.

[0031] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means greater than or equal to X and less than or equal to Y. For example, "1 to 5 mass %" means "1 mass % or more and 5 mass % or less".

[0032] In the description of the group (atomic group) in this specification, the description without recording whether it is substituted or unsubstituted includes both the group without a substituent and the group with a substituent. For example, "alkyl" includes not only the alkyl group without a substituent (unsubstituted alkyl group) but also the alkyl group with a substituent (substituted alkyl group).

[0033] The term "(meth)acrylic acid" in this specification is a concept including both acrylic acid and methacrylic acid. The same applies to similar terms such as "(meth)acrylate".

[0034] The term "polyfunctional (meth)acrylate" in this specification refers to a compound having two or more (meth)acryloyl groups in one molecule. The term "monofunctional (meth)acrylate" refers to a compound having only one (meth)acryloyl group in one molecule.

[0035] Unless otherwise specified, the term "organic group" in this specification refers to an atomic group obtained by removing one or more hydrogen atoms from an organic compound. For example, a "monovalent organic group" means an atomic group obtained by removing one hydrogen atom from any organic compound.

[0036] In this specification, unless otherwise specified, the term "PET" means polyethylene terephthalate.

[0037] <Photosensitive composition>

[0038] The photosensitive composition of this embodiment contains a polymerizable compound and a photopolymerization initiator.

[0039] The photosensitive composition of the present embodiment is preferably used for sealing an organic electroluminescent element. That is, the photosensitive composition of the present embodiment is preferably used for sealing an organic EL element to produce an organic EL display device.

[0040] The dissolved oxygen concentration in the photosensitive composition of the present embodiment is preferably 0.1 mg / L or more and 20 mg / L or less.

[0041] The water concentration in the photosensitive composition of this embodiment is 1 ppm or more and 50 ppm or less.

[0042] The toluene concentration in the photosensitive composition of this embodiment is set to a, and the composition is irradiated with 1500 mJ / cm 2 When the toluene concentration in the cured film obtained by emitting light of a wavelength of 395 nm from an LED lamp is defined as b, ab is 50 ppm or less.

[0043] The photosensitive composition of this embodiment has a small ab and is less likely to pollute the environment. For example, in the current situation where reducing VOC emissions is important, the photosensitive composition of this embodiment with a small ab can be easily handled industrially.

[0044] In addition, a small ab, that is, less toluene released outside the film when the film is formed, means that less toluene is released during the manufacturing process of the organic EL display device, so toluene is not easy to corrode the organic EL element. That is, by using the photosensitive composition of this embodiment with a small ab to seal the organic EL element, the reliability of the organic EL display device can be improved.

[0045] Incidentally, the composition of the present embodiment is a "photosensitive composition". That is, the photosensitive composition of the present embodiment is cured by light irradiation. By sealing the organic EL element (curing the composition) with light instead of heat, the release of toluene and other components can be further reduced. That is, it is considered that the composition of the present embodiment is "photosensitive", and it is not necessary to heat for curing, and it is not easy to pollute the environment, and the reliability of the organic EL display device is improved.

[0046] In the photosensitive composition of this embodiment, it is considered that the water concentration is 1 ppm to 50 ppm, and the dissolved oxygen concentration is preferably 0.1 mg / L to 20 mg / L, which also contributes to the improvement of the reliability of the organic EL display device.

[0047] As a structure of an organic EL display device, an inorganic protective film with a film thickness of about 1 μm is usually provided between the organic EL element and the sealing material (cured material). When pinholes are generated in the inorganic protective film, water and oxygen invade the organic EL element from the pinholes, so that the reliability of the organic EL element is reduced. Therefore, by using a photosensitive composition having a water concentration of 1 ppm to 50 ppm (preferably a dissolved oxygen concentration of 0.1 mg / L to 20 mg / L) to seal the organic EL element, even if pinholes are generated in the inorganic protective film, the reliability of the organic EL element is not easily damaged (because the water and oxygen that invade the organic EL element from the pinholes are originally small).

[0048] The photosensitive composition of this embodiment is manufactured by selecting appropriate materials and selecting appropriate manufacturing conditions. Regarding "appropriate materials", for example, (i) using a polymerizable compound with low volatility, (ii) preparing the photosensitive composition substantially without solvent, etc. Regarding "appropriate manufacturing conditions", for example, (i) devolatilizing the polymerizable compound and the photopolymerization initiator of the raw material, (ii) dehydrating by molecular sieves, and (iii) deoxygenating by decompression and nitrogen bubbling. The details will be described later.

[0049] Next, the specific description regarding the photosensitive composition of this embodiment will be given.

[0050] (Polymerizable compound)

[0051] The polymerizable compound is not particularly limited as long as it is a compound that can be polymerized by an active species generated by a photopolymerization initiator described below.

[0052] In the present embodiment, the polymerizable compound preferably includes a (meth)acrylate compound. The (meth)acrylate compound will be described below.

[0053] The polymerizable compound preferably contains a polyfunctional (meth)acrylate compound. The use of a polyfunctional (meth)acrylate compound tends to improve the photocurability.

[0054] The polyfunctional (meth)acrylate compound may include, for example, a 2-6-functional (meth)acrylate compound, and specifically, a 2-4-functional (meth)acrylate compound. In terms of the balance of various properties, the polyfunctional (meth)acrylate compound preferably includes a 2-functional (meth)acrylate compound, that is, a di(meth)acrylate compound.

[0055] The polymerizable compound preferably contains a polyfunctional (meth)acrylate and a monofunctional (meth)acrylate. By using a polyfunctional (meth)acrylate and a monofunctional (meth)acrylate in combination, it is possible to adjust the polymerizability, adjust the physical properties of the cured film, and the like.

[0056] From the viewpoint of balancing various properties, when a multifunctional (meth) acrylate and a monofunctional (meth) acrylate are used in combination, preferably more than 40% by mass of the entire polymerizable compound, more preferably more than 50% by mass of the entire polymerizable compound is a multifunctional (meth) acrylate. Preferably more than 70% by mass of the entire polymerizable compound, more preferably more than 80% by mass of the entire polymerizable compound, and most preferably more than 90% by mass of the entire polymerizable compound is a multifunctional (meth) acrylate. Preferably less than 100% by mass of the entire polymerizable compound, more preferably less than 95% by mass of the entire polymerizable compound is a multifunctional (meth) acrylate.

[0057] It should be noted that the polymerizable compound may contain only monofunctional (meth)acrylate as long as the performance is good.

[0058] As a specific example of the polyfunctional (meth)acrylate compound, the following compounds are mentioned, for example.

[0059] The following bifunctional (meth)acrylates. Bis(1-(meth)acryloyloxy-2-hydroxypropyl)phthalate, bis(2-(meth)acryloyloxyethyl)phosphate, bis((meth)acryloyloxy-2-hydroxypropyloxy)diethylene glycol, bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, bisphenol A di-(3-(meth)acryloyloxyethyl)ether, bisphenol A di-(3-(meth)acryloyloxy-2-hydroxypropyl)ether, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di-(3-(meth)acryloyloxy-2-hydroxypropyl)ether, 1,4-butylene glycol di(meth)acrylate acrylate, 1,3-butanediol bis((meth)acryloyloxypropionate), 1,4-butanediol bis((meth)acryloyloxypropionate), 2-butene-1,4-diol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, 2,2-dimethyl-1,3-propanediol di(meth)acrylate, dipentaerythritol ether di(meth)acrylate, diphenolic acid di-(3-(meth)acryloyloxy-2-hydroxypropyl) ether, dipropylene glycol di(meth)acrylate, 7,7,9-trimethylolpropane -3,13-dioxo-3,14-dioxa-5,12-diazahexadecane-1,16-diol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,2-ethylene glycol bis((meth)acryloyloxypropionate), 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,4-phenylene di(meth)acrylate, 1-phenyl-1,2-ethylene glycol di(meth)acrylate, polyoxyethyl-2,2-di(p-hydroxypropionate) 1,2-propylene glycol di(meth)acrylate, 1,3-propylene glycol di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, tetrabromobisphenol A di-(3-(meth)acryloyloxy-2-hydroxypropyl) ether, tetrachlorobisphenol A di-(3-(meth)acryloyloxy-2-hydroxypropyl) ether, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2,2,4-trimethyl-1,3-pentanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, dihydroxymethyl-tricyclodecane di(meth)acrylate.

[0060] The following trifunctional (meth)acrylates: 1,2,4-butanetriol tri(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, polyoxypropyl trimethylolpropane tri(meth)acrylate, silicone tri(meth)acrylate, 1,3,5-tri(meth)acryloylhexahydro-s-triazine, trimethylolethane tri(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate, 1,2,3-trimethylolpropane tri(meth)acrylate, 1,1,1-trimethylolpropane tri((meth)acryloyloxypropionate), 1,2,3-trimethylolpropane tri((meth)acryloyloxypropionate), tris-(2-(meth)acryloyloxyethyl)isocyanurate.

[0061] The following tetrafunctional (meth)acrylates: Pentaerythritol tetra(meth)acrylate, pentaerythritol tetra((meth)acryloyloxypropionate).

[0062] As a specific example of the monofunctional (meth)acrylate compound, the following can be mentioned, for example.

[0063] Methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, n-octyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate.

[0064] In the devolatilization process described later, from the viewpoint of fully devolatilizing toluene and leaving the polymerizable compound (non-volatile), the polymerizable compound preferably includes a polymerizable compound that is not easily volatile. Specifically, the polymerizable compound preferably includes a polymerizable compound with a molecular weight of 210 to 2000, more preferably includes a polymerizable compound with a molecular weight of 300 to 2000, further preferably includes a polymerizable compound with a molecular weight of 300 to 1000, and particularly preferably includes a polymerizable compound with a molecular weight of 300 to 600. That is, the photosensitive composition of the present embodiment preferably includes a photosensitive composition that meets the above molecular weight in the above-mentioned (meth) acrylate compound (especially multifunctional (meth) acrylate). More specifically, the photosensitive composition of the present embodiment preferably includes more than 50% by mass of polymerizable compounds that meet the above molecular weight in all polymerizable compounds.

[0065] It should be noted that even polymerizable compounds that do not meet the above molecular weights are not excluded from use in this embodiment.

[0066] (Photopolymerization Initiator)

[0067] The photopolymerization initiator is not particularly limited as long as it can polymerize the above-mentioned polymerizable compound.

[0068] The photopolymerization initiator preferably contains a photoradical polymerization initiator. Examples of the photoradical polymerization initiator include benzophenone and its derivatives, benzil and its derivatives, anthraquinone and its derivatives, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzoin derivatives such as benzil dimethyl ketal, diethoxyacetophenone, acetophenone derivatives such as 4-tert-butyltrichloroacetophenone, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone and its derivatives, camphorquinone, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid-2-bromoethyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid-2-methyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid-2-methyl ester, [2.2.1] Camphorquinone derivatives such as heptane-1-carbonyl chloride, α-aminoalkylphenone derivatives such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzoyldiethoxyphosphine oxide, 2,4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, phenyl-glyoxylic acid methyl ester, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, etc.

[0069] The photopolymerization initiator can be used alone or in combination of two or more.

[0070] As a photopolymerization initiator, when curing, only visible light of 390 nm or more can be used to cure it. From the perspective of being able to cure it without damaging the organic EL display element, acylphosphine oxide derivatives are preferred. Among the acylphosphine oxide derivatives, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is most preferred from the perspective of not reducing the transmittance under visible light when making an organic EL display device and being able to cure it only using light of 395 nm or more. As 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, "Omnirad TPO" manufactured by IGM Resins Co., Ltd. can be cited.

[0071] The content of the photopolymerization initiator is preferably 0.05 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, further preferably 1 to 5 parts by mass, and particularly preferably 2 to 5 parts by mass. By using an appropriate amount of photopolymerization initiator, sufficient sensitivity / curing speed can be easily obtained, and the transparency of the sealing material can be fully ensured.

[0072] (Other optional ingredients)

[0073] The photosensitive composition of the present embodiment may or may not contain other components in addition to the polymerizable compound and the photopolymerization initiator in order to adjust the performance.

[0074] Examples of other components include antioxidants, surfactants, and sensitizers.

[0075] It is not excluded that the photosensitive composition of the present embodiment contains an organic solvent. However, from the viewpoint of making ab less than 50 ppm, the photosensitive composition of the present embodiment preferably does not substantially contain an organic solvent, or even if it contains, it is a small amount. Specifically, the amount of the organic solvent is preferably less than 5% by mass in the photosensitive composition as a whole, more preferably less than 3% by mass, further preferably less than 1% by mass, and particularly preferably less than 0.1% by mass. Ideally, the photosensitive composition of the present embodiment does not substantially contain an organic solvent.

[0076] Many organic solvents that are easily used industrially contain toluene as an impurity. Therefore, by preparing a photosensitive composition substantially without using an organic solvent, it is easy to prepare a photosensitive composition having ab of 50 ppm or less.

[0077] (About the addition and supplementary explanation of various numerical values)

[0078] As described above, ab only needs to be 50 ppm or less, preferably 30 ppm or less, and more preferably 15 ppm or less. ab is ideally zero, but in practice, ab is, for example, 1 ppm or more, specifically, 3 ppm or more.

[0079] The value of the toluene concentration a itself is preferably 1 ppm to 100 ppm, more preferably 1 ppm to 80 ppm, and even more preferably 1 ppm to 50 ppm. The value of the toluene concentration b itself is also preferably the same. By making the toluene concentration a and / or b within the above numerical range, for example, the corrosion of the organic EL element caused by toluene can be further suppressed, and the reliability of the organic EL display device can be further improved.

[0080] For details of the method for measuring the toluene concentration a and the toluene concentration b, refer to the examples described later.

[0081] As described above, the dissolved oxygen concentration in the photosensitive composition of this embodiment is preferably 0.1 mg / L to 20 mg / L, more preferably 0.1 mg / L to 10 mg / L, and particularly preferably 0.1 mg / L to 5 mg / L.

[0082] For the method of measuring the dissolved oxygen concentration, please refer to the description of Examples described later.

[0083] The viscosity of the photosensitive composition of this embodiment is preferably 3 mPa·s to 50 mPa·s, more preferably 5 mPa·s to 30 mPa·s. This viscosity improves the ease of ejection and film formation when the inkjet method is applied.

[0084] The viscosity change of the photosensitive composition of this embodiment at 80°C for 16 hours is preferably less than 3 mPa·s, more preferably less than 2 mPa·s, and further preferably less than 1 mPa·s. By designing the photosensitive composition in this way, the storage property of the photosensitive composition is improved, that is, the ease of industrial handling is further improved. In addition, if a film is formed under certain conditions, it is usually easy to obtain a cured film with certain properties, which is effective for improving the yield of organic EL display devices.

[0085] The inventors of the present invention have found that by mainly using methacrylate, which has a lower reactivity than acrylate, as the polymerizable compound, it is easy to design the viscosity change after 16 hours at 80° C. to fall within the above range.

[0086] The viscosity can be measured, for example, using a cone-plate viscometer (manufactured by Eiko Seiki Co., Ltd., product number: HB DV3T, etc.) at 25° C. and 200 to 250 rpm (preferably 250 rpm).

[0087] The mass reduction of the photosensitive composition of the present embodiment when left to stand at 23° C. for 16 hours is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less.

[0088] Here, the mass reduction is calculated as follows: a film of a photosensitive composition is formed on an alkali-free glass using an inkjet device, the resultant is left to stand at 23°C for 16 hours, and the weight is calculated based on the mathematical formula {(weight before standing - weight after standing) / weight before standing} × 100 (%). The weight before standing and the weight after standing are calculated by subtracting the weight of the alkali-free glass from the weight of "alkali-free glass + the photosensitive composition on which the film is formed". For details of the measurement conditions, please refer to the Examples described below.

[0089] <Method for producing photosensitive composition>

[0090] The photosensitive composition of this embodiment can be produced by using the above-mentioned components and adopting an appropriate production method. Specifically, the photosensitive composition of this embodiment can be produced by going through each process of (1) devolatilization of raw materials, (2) mixing of raw materials, (3) dehydration, (4) deoxidation, and (5) filtration.

[0091] These steps are described below.

[0092] (1) Devolatilization process of raw materials

[0093] It is preferred to fully devolatilize a part or all of the raw materials before mixing. By performing this process, it is particularly easy to produce a photosensitive composition with ab of 50 ppm or less. It is particularly preferred to devolatilize a polymerizable compound used in a large amount.

[0094] The temperature during devolatilization is preferably 10°C to 100°C, more preferably about 30°C to 80°C.

[0095] The time for devolatilization is preferably 10 minutes or longer, more preferably 10 minutes or longer and 60 minutes or shorter.

[0096] The pressure during devolatilization can be preferably set to 1000 Pa or less, and more preferably 1 Pa or more and 1000 Pa or less.

[0097] The devolatilization treatment can be carried out on a laboratory scale, for example, by placing a stirrer in a flask and connecting a vacuum pump and a vacuum gauge to reduce the pressure. When it is desired to heat to volatilize the volatile components more actively, it is preferable to use an oil bath.

[0098] In order to maintain an appropriate vacuum degree, air may be bubbled (blown into the liquid) because if the concentration of oxygen that deactivates polymerization active species is excessively reduced, the polymerizable compound may polymerize.

[0099] When the devolatilization treatment is performed on a large scale, it can be performed in, for example, a stainless steel pressure vessel equipped with a stirrer.

[0100] (2) Raw material mixing process

[0101] The devolatilized raw materials in the above (1) are mixed in appropriate amounts to obtain a mixture. The mixing method is not particularly limited, and a known stirrer can be used for stirring.

[0102] (3) Dehydration process

[0103] Water is removed as much as possible from the mixture obtained in (2) above. The method for reducing the water content is not particularly limited, and examples thereof include the following methods.

[0104] (i) Use a desiccant. After removing the water, separate the desiccant by decantation or filtration. The desiccant is not particularly limited as long as it has no effect on the composition. Examples of desiccant include polymer adsorbents (molecular sieves, synthetic zeolites, alumina, silica gel, etc.), inorganic salts (calcium chloride, anhydrous magnesium sulfate, quicklime, anhydrous sodium sulfate, anhydrous calcium sulfate, etc.), solid alkalis (sodium hydroxide, potassium hydroxide, etc.), etc.

[0105] (ii) Heating under reduced pressure.

[0106] (iii) Purification by distillation under reduced pressure.

[0107] (iv) An inert gas such as dry nitrogen or dry argon is blown into each component.

[0108] (v) freeze-drying.

[0109] As a method for reducing the water content, a method using a molecular sieve is preferred from the viewpoints of simplicity and suppression of degradation of components.

[0110] (4) Deoxidation process

[0111] The deoxygenation step can reduce the amount of dissolved oxygen in the mixture. The method for reducing dissolved oxygen is not particularly limited, and examples thereof include the following methods.

[0112] (i) exposing the mixture to reduced pressure.

[0113] (ii) An inert gas such as dry nitrogen or dry argon is blown into the mixture.

[0114] (iii) Exposure to low oxygen concentrations.

[0115] In addition, the dissolved oxygen may be reduced by combining two or more of the above methods. For example, the dissolved oxygen content in the mixture may be reduced by combining methods (i) and (ii), i.e., blowing an inert gas such as dry nitrogen or dry argon into the mixture under reduced pressure.

[0116] (5) Filtration process

[0117] The mixture obtained through the above steps (1) to (4) is filtered using an appropriate filter. Thus, the photosensitive composition of the present embodiment can be obtained. The filter that can be used is not particularly limited, but in order to obtain a photosensitive composition of the specifications required for the sealing application of an organic EL element, a filter with a pore size of 1 μm or less is preferably used.

[0118] <Solidified materials, organic EL display devices>

[0119] By irradiating the photosensitive composition of this embodiment with light, a cured product can be obtained. In addition, by sealing an organic EL element with the photosensitive composition of this embodiment, an organic EL display device can be manufactured.

[0120] The light source used to cure the photosensitive composition is not particularly limited, and examples thereof include halogen lamps, metal halide lamps, high-power metal halide lamps (containing indium, etc.), low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, xenon excimer lamps, xenon flash lamps, LEDs, and the like.

[0121] As a method for manufacturing an organic EL display device, for example, the following method can be cited: (i) forming a film (uncured film) based on the photosensitive composition of this embodiment on the surface of the substrate provided with the organic EL element; (ii) irradiating the film with light. Thus, the organic EL element can be sealed with the cured product of the photosensitive composition of this embodiment. As described above, by sealing the organic EL element with the cured product of the photosensitive composition of this embodiment, the reliability of the organic EL display device finally obtained can be improved.

[0122] Furthermore, after the above step (ii), an inorganic protective film such as SiN may be further provided on the surface of the cured product.

[0123] In the film formation of (i) above, it is preferable to use an inkjet method. In the manufacture of an organic EL display device, it is necessary to uniformly form a film on a large-area substrate on which a plurality of organic EL elements are provided, and therefore it is preferable to form the film using an inkjet method.

[0124] In the film formation of (i) above, the film thickness is, for example, 1 μm to 10 μm, preferably 3 μm to 9 μm. By forming a film of 1 μm or more and then curing it, it is easy to obtain sufficient sealing ability as a sealing material. In addition, by making the film thickness less than 10 μm, it is possible to achieve miniaturization of the organic EL display device and reduce manufacturing costs.

[0125] The embodiments of the present invention are described above, but these are examples of the present invention, and various configurations other than the above can be adopted. In addition, the present invention is not limited to the above-mentioned embodiments, and modifications and improvements within the scope of achieving the purpose of the present invention are included in the present invention.

[0126] Example

[0127] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. It should be noted that the present invention is not limited to the Examples.

[0128] <Production of photosensitive composition>

[0129] (Examples 1 to 8)

[0130] The photosensitive compositions of Examples 1 to 8 were prepared using the polymerizable compounds and photopolymerization initiators described in the tables below. The specific procedures are as follows.

[0131] (1) Devolatilization process

[0132] The polymerizable compound was subjected to devolatilization treatment under the conditions of 23° C. or higher, 15 minutes or higher, and 1000 Pa or lower.

[0133] (2) Mixing process

[0134] The devolatilized polymerizable compound and the photopolymerization initiator were weighed in the amounts (unit: parts by mass) listed in the table, and stirred at 200 rpm and 23° C. for 3 hours using a stirrer (Three-One Motor). Thus, a mixture was obtained.

[0135] (3) Dehydration process

[0136] To the mixture obtained in the above (2), 10 mass % of a dehydrating agent (molecular sieve 5A) was added, and the mixture was allowed to stand at 23° C. for 16 hours.

[0137] (4) Deoxidation process

[0138] The mixture that has undergone the dehydration step (3) is bubbled with nitrogen gas at a pressure of 1000 Pa or less for 30 minutes or more.

[0139] (5) Filtration process

[0140] The mixture that has been subjected to the deoxidation step (4) is filtered through a filter having a pore size of 1 μm or less to remove foreign matter.

[0141] In this way, a photosensitive composition is produced.

[0142] (Comparative Example 1)

[0143] (1) A photosensitive composition was produced in the same manner as in Example 2 except that the devolatilization step was not performed.

[0144] (Comparative Example 2)

[0145] (3) A photosensitive composition was produced in the same manner as in Example 1 except that the dehydration step was not performed.

[0146] (Comparative Example 3)

[0147] Photosensitive compositions were prepared in the same manner as in Examples 1 to 8 except that the type and amount of the polymerizable compound were changed as described in the table.

[0148] For reference, the methods of obtaining the polymerizable compound and initiator used this time are described.

[0149] SR262 (1,12-dodecanediol dimethacrylate, molecular weight 338): Arkema

[0150] · BPE200 (ethoxylated bisphenol A dimethacrylate (m+n=4 in the following chemical formula), molecular weight 540): Shin-Nakamura Chemical Industry Co., Ltd.

[0151] [Chemical formula 1]

[0152]

[0153] · A-LEN-10 (ethoxylated o-phenylphenol acrylate (2-(o-phenylphenoxy)ethyl acrylate), molecular weight 268): Shin-Nakamura Chemical Industry Co., Ltd.

[0154] ·TMPTA (trimethylolpropane triacrylate, molecular weight 296): Osaka Organic Chemical Industry Co., Ltd.

[0155] ·DCP (dihydroxymethyl-tricyclodecane dimethacrylate, molecular weight 332): Shin-Nakamura Chemical Industry Co., Ltd.

[0156] LA (lauryl acrylate, molecular weight 240): Osaka Organic Chemical Industry Co., Ltd.

[0157] · EHMA (2-ethylhexyl methacrylate, molecular weight 198): MITSUBISHI GAS CHEMICAL

[0158] ·TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide): IGM Resins

[0159] <Various Measurements / Evaluations>

[0160] (Toluene concentration a in the composition)

[0161] 0.200 g of the photosensitive composition was weighed in a 20 mL volumetric flask, and acetone was added to the target mark. The mixture was then shaken and mixed thoroughly to prepare a sample for measurement. The sample for measurement was then added to a gas chromatograph to quantify the toluene concentration. The details of the gas chromatograph are as follows.

[0162] Device: Agilent 7890B

[0163] Chromatographic column (Col.):

[0164] Column temperature (Col. Temp.): Keep at 40°C for 1 minute, then increase the temperature to 180°C at a rate of 20°C / min, then increase the temperature to 300°C at a rate of 10°C / min, and then keep at this temperature for 50 minutes

[0165] Inj.Temp.: 300℃

[0166] Detection temperature (Det.Temp.): 300℃

[0167] Flow rate: 1 mL / min x 22 min, then 0.1 mL / min, then 2 mL / min, split 1 / 20

[0168] Injection volume (Inj): 1μL

[0169] (Toluene concentration in cured film b)

[0170] The toluene concentration b was calculated by the following steps.

[0171] (1) A photosensitive composition was applied (dropped) onto a first PET film with a spacer tape having a thickness of 100 μm, and a second PET film was laminated from above to obtain a sample in which an uncured photosensitive composition was sandwiched between the first PET film and the second PET film.

[0172] (2) Irradiate the sample with 750 mJ / cm2 of radiation from the front and back of the sample. 2 (Total 1500mJ / cm 2 ) is emitted from an LED lamp with a wavelength of 395 nm. Thus, a cured film of the photosensitive composition is obtained.

[0173] (3) Carefully peel the cured film from the first PET film and the second PET film.

[0174] (4) 0.5 g of the cured film was cut into pieces of 5 mm square or less, then placed in a screw-cap bottle, injected with 5 mL of acetone, and ultrasonic waves were applied for 30 minutes. Then, it was left for a day and night, and filtered with a membrane filter with a pore size of 0.45 μm to obtain a filtrate. The filtrate was added to a gas chromatograph to quantify the toluene concentration (the various conditions of the gas chromatograph were the same as those described above (determination of the toluene concentration a in the composition)).

[0175] (Dissolved oxygen concentration)

[0176] The dissolved oxygen concentration in the photosensitive composition was measured at 23° C. under stirring using a dissolved oxygen meter, DO meter B-506S (diaphragm type galvanic cell type) manufactured by Iijima Electronics Co., Ltd.

[0177] (Water concentration (water content))

[0178] AQUAMICRON AX (manufactured by Mitsubishi Chemical Corporation) was used as a Karl Fischer solution, and the measurement was performed with a trace water content measuring apparatus CA-06 (manufactured by Mitsubishi Chemical Corporation).

[0179] (Mass reduction (volatility))

[0180] The material obtained by forming a film of a photosensitive composition on an alkali-free glass using an inkjet device was left to stand at 23° C. for 16 hours. Then, the mass reduction was calculated based on the mathematical formula of {(mass before standing - mass after standing) / mass before standing}×100(%). The mass before standing and the mass after standing in the formula were obtained by subtracting the mass of the alkali-free glass from the mass of "alkali-free glass + the photosensitive composition on which the film was formed".

[0181] The details are supplemented below.

[0182] Inkjet device: FUJIFILM, DMP2850

[0183] Inkjet conditions: At 23°C, ink droplets were ejected in a 35 mm square area to a film thickness of 10 μm.

[0184] Static conditions: open system (air), clean room (class 1000), under yellow light, humidity about 40%

[0185] (Viscosity and its changes (heating stability))

[0186] The viscosity of the photosensitive composition was measured at 25° C. and 250 rpm using a cone-plate viscometer (manufactured by Eikon Seiki Co., Ltd., HB DV3T, cone-plate: CPA-40Z).

[0187] The photosensitive composition was subjected to the same operation to measure the viscosity after 16 hours at 80° C. to evaluate the heating stability. As the evaluation criteria, a viscosity change of less than 3 mPa·s was regarded as 0 (no change), and a viscosity change of 3 mPa·s or more was regarded as × (increased viscosity).

[0188] (Reliability Evaluation of Organic EL Display Devices (Organic EL Reliability))

[0189] ·Production of organic EL display elements for evaluation

[0190] A 30 mm square glass substrate with an ITO electrode (thickness 700 μm) was cleaned using acetone and isopropanol, respectively. Then, the following compounds were sequentially deposited in a thin film manner using a vacuum evaporation method to obtain a substrate having an organic EL element of 2 mm square consisting of an anode / hole injection layer / hole transport layer / luminescent layer / hole blocking layer / electron transport layer / electron injection layer / cathode. The composition of each layer is as follows.

[0191] Anode (ITO): 150nm / polymer

[0192] Hole injection layer (polymer HIL): 60nm

[0193] Hole transport layer (α-NPD): 30nm

[0194] Light-emitting layer (Ir(ppy)3+CBP[6%]): 30nm

[0195] Void blocking layer (BAlq): 10nm

[0196] Electron transport layer (Alq3): 30nm

[0197] Electron injection layer (LiF): 0.8nm

[0198] Cathode (MgAg / IZO): 10nm / 100nm

[0199] Next, in a nitrogen atmosphere, an inkjet device (product number: DMP2850) manufactured by FUJIFILM was used to eject ink droplets in a manner that covered an organic EL element of 2 mm × 2 mm, thereby obtaining a photosensitive resin film with a thickness of 10 μm. Then, in an N2 environment, an LED lamp (UV-LED LIGHT SOURCE H-4MLH200-V1 manufactured by HOYA) emitting light at a wavelength of 395 nm was used, with a cumulative light amount of 1,500 mJ / cm at a wavelength of 395 nm. 2 The photosensitive film is irradiated with light under the conditions of . Thus, a cured film is obtained.

[0200] A mask (cover) having an opening of 10 mm×10 mm was set to cover the entire obtained cured film, and then a SiN film was formed by plasma CVD. The thickness of the formed SiN (inorganic film) was about 1 μm. Thus, an organic EL element was obtained.

[0201] The obtained organic EL element was bonded to alkali-free glass (Eagle XG manufactured by Corning) of 30 mm×30 mm×0.7 mmt using a transparent double-sided tape without a substrate of 30 mm×30 mm×25 μmt. Thus, an organic EL display device for evaluation was prepared.

[0202] Reliability test

[0203] The organic EL display device for evaluation obtained as described above was placed in a high temperature and high humidity environment of 85°C and 85%RH for 500 hours for treatment. Before and after the high temperature and high humidity treatment, a current was passed through the organic EL display device for evaluation, and the luminous surface was photographed. The image analysis software "Quick Grain" of Innotech was used to analyze the photographed images (before and after the high temperature and high humidity treatment) to find the luminous area. Then, the luminous area reduction rate (%) before and after the high temperature and high humidity treatment was calculated.

[0204] Information related to Examples and Comparative Examples is summarized in the following table.

[0205] [Table 1]

[0206]

[0207] As shown in the above table, ab of the photosensitive compositions of Examples 1 to 8 was 1 ppm or more and 50 ppm or less. That is, it can be said that the photosensitive compositions of Examples 1 to 8 are unlikely to pollute the environment and are easy to handle industrially.

[0208] Furthermore, it can be understood from the evaluation results of the light emitting area reduction rate that the reliability of the organic EL display devices produced using the photosensitive compositions of Examples 1 to 8 is better than that of the comparative example.

[0209] In addition, as can be understood from the comparison between Examples 1 to 7 and Example 8, there is a tendency that the reliability of the organic EL display device can be further improved by reducing the dissolved oxygen concentration of the photosensitive composition.

[0210] For reference, comparative examples are supplemented.

[0211] Comparative Example 1: It is considered that the reliability of the organic EL display device was reduced because the ab of the photosensitive composition was large (that is, because a large amount of toluene was released when the organic EL element was sealed).

[0212] Comparative Example 2: It is considered that the reliability of the organic EL display device was reduced because the water concentration of the photosensitive composition was high.

[0213] Comparative Example 3: ab of the photosensitive composition is large. In Comparative Example 3, the polymerizable compound TMPTA thickened during the devolatilization treatment during the production of the photosensitive composition, and thus a photosensitive composition having a viscosity sufficient for inkjetting could not be produced.

[0214] This application claims the benefit of priority based on Japanese patent application No. 2020-063227, filed on March 31, 2020, the disclosure of which is incorporated herein in its entirety.

Claims

1. A photosensitive composition comprising a polymerizable compound and a photopolymerization initiator, The water concentration in the composition is 1 ppm or more and 50 ppm or less. When the toluene concentration in the composition is set to a, The composition was irradiated with 1500 mJ / cm 2 When the toluene concentration in the cured film obtained by emitting light of 395 nm wavelength from an LED lamp is set to b, ab is less than 50ppm, The photosensitive composition had a viscosity change of less than 3 mPa·s after being heated at 80° C. for 16 hours.

2. The photosensitive composition according to claim 1, wherein The dissolved oxygen concentration in the composition is 0.1 mg / L or more and 20 mg / L or less. 3 . The photosensitive composition according to claim 1 , which has a viscosity of 3 mPa·s to 50 mPa·s.

4. The photosensitive composition according to claim 1 or 2, wherein The mass reduction of the photosensitive composition when left to stand at 23° C. for 16 hours was 10% or less.

5. The photosensitive composition according to claim 1 or 2, wherein The toluene concentration a is greater than 1 ppm and less than 100 ppm, The toluene concentration b is greater than or equal to 1 ppm and less than or equal to 100 ppm.

6. The photosensitive composition according to claim 1 or 2, wherein The polymerizable compound includes a polymerizable compound having a molecular weight of 300 to 2000.

7. The photosensitive composition according to claim 1 or 2, wherein The polymerizable compound includes a (meth)acrylate compound.

8. The photosensitive composition according to claim 1 or 2, which is used for sealing an organic electroluminescent element. 9 . A cured product of the photosensitive composition according to claim 1 .

10. An organic electroluminescent display device, wherein an organic electroluminescent element is sealed with the cured product according to claim 9.

11. A method for producing a photosensitive composition, which is the method for producing a photosensitive composition according to any one of claims 1 to 8, The manufacturing method comprises: A process of decompressing the polymerizable compound to below 1000 Pa at 10-100° C. for more than 10 minutes; A mixing step of mixing the devolatilized polymerizable compound and the photopolymerization initiator to obtain a mixture; a dehydration step to reduce the water content of the mixture; and A deoxygenation step is performed to reduce the amount of dissolved oxygen in the mixture.

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