JP7555002B2 - Composition for sealing light-emitting element, and light-emitting device - Google Patents

Description

The present invention relates to a composition for sealing light-emitting elements and a light-emitting device, and more specifically, to a composition for sealing light-emitting elements used as a sealant for covering light-emitting elements, and a light-emitting device comprising a cured product of this composition for sealing light-emitting elements.

Light-emitting devices equipped with light-emitting elements such as light-emitting diodes are used for lighting and display purposes, and are expected to become even more widespread in the future.

When sealing the light-emitting element of a light-emitting device, for example, an ethylenically unsaturated compound such as an allyl compound and an acrylic compound is mixed into a composition, and the composition is applied so as to cover the light-emitting element and then cured to produce a sealant.

For example, Patent Document 1 discloses a curable composition containing an ethylenically unsaturated compound, a photopolymerization initiator, a polyfunctional thiol compound, an organic solvent, etc., and proposes creating a cured film from this curable composition and using it in an organic EL device, etc. It also discloses that this curable composition can be used in an inkjet method.

JP 2017-151321 A

However, the curable composition disclosed in Patent Document 1 has a problem in that the stability of the curable composition during storage is reduced because the viscosity is adjusted by including a solvent. In addition, when a solvent is blended into the composition, outgassing is likely to occur from a cured product produced from the composition. Furthermore, drying the composition or the cured product to prevent outgassing from the cured product leads to a decrease in the efficiency of producing the cured product.

The object of the present invention is to provide a composition for sealing light-emitting elements that can reduce the need for viscosity adjustment using a solvent when molding using an inkjet method, and a light-emitting device that uses this composition for sealing light-emitting elements.

The composition for sealing a light-emitting element according to one embodiment of the present invention contains a polythiol compound (A) having two or more thiol groups in one molecule, an acrylic compound (B), and a photopolymerization initiator (C). The viscosity of the polythiol compound (A) at 25°C is 2000 mPa·s or less. The composition for sealing a light-emitting element is molded by an inkjet method.

The light-emitting device according to one aspect of the present invention includes a light-emitting element and a sealant that covers the light-emitting element. The sealant is a cured product of the composition for sealing the light-emitting element.

One aspect of the present invention has the advantage of providing a composition for sealing light-emitting elements that can reduce the need for viscosity adjustment using a solvent when molding using an inkjet method, and a light-emitting device that includes a sealant made from this composition for sealing light-emitting elements.

1 is a schematic cross-sectional view showing a first example of a light emitting device according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a second example of a light emitting device according to one embodiment of the present invention.

1. Composition for sealing light-emitting device One embodiment of the present invention will be described below.

The composition for sealing a light-emitting element according to this embodiment (hereinafter also referred to as composition (X)) contains a polythiol compound (A) having two or more thiol groups in one molecule, an acrylic compound (B), and a photopolymerization initiator (C). The viscosity of the polythiol compound (A) at 25°C is 2000 mPa·s or less. This composition (X) is molded by the inkjet method.

The composition (X) of this embodiment contains the polythiol compound (A), which allows it to have good storage stability.

In addition, since the viscosity of the polythiol compound (A) at 25°C is 2000 mPa·s or less, the polythiol compound (A) is unlikely to increase the viscosity of the composition (X). Therefore, when molding the composition (X) by the inkjet method, the need for viscosity adjustment with a solvent can be reduced.

As a result, in this embodiment, even if composition (X) does not contain a solvent or contains a small amount of solvent, it is possible to mold composition (X) by the inkjet method. When composition (X) does not contain a solvent or contains a small amount of solvent, the composition and viscosity of the composition are unlikely to change due to evaporation of the solvent, and the storage stability of composition (X) is improved. In addition, outgassing is unlikely to occur from the cured product produced from composition (X). Therefore, the cured product of composition (X) can be suitably used as an encapsulant for encapsulating light-emitting elements.

Furthermore, when the composition (X) is molded, particularly by the inkjet method, foreign matter is less likely to be mixed into the composition (X) and its cured product, and therefore the yield is less likely to deteriorate when producing the sealant 5 that covers the light-emitting element 4. This makes it possible to improve the manufacturing efficiency of the light-emitting device 1 that includes the light-emitting element 4 and the sealant 5 that covers the light-emitting element 4.

The high storage stability of composition (X), good moldability in the inkjet method (inkjet printability), and suppression of outgassing can be achieved by the composition of composition (X), which will be described in detail below.

The viscosity of the composition (X) at 25°C is preferably 1 mPa ·s or more and 30 mPa· s or less. In this case, the composition (X) can be applied by the inkjet method at room temperature and molded. In particular, if the viscosity is 30 mPa·s or less, the discharge speed of the composition (X) from the nozzle is unlikely to decrease when the composition (X) is applied by the inkjet method. It is more preferable that the viscosity is 20 mPa·s or less, and even more preferable that the viscosity is 15 mPa·s or less. It is also preferable that the viscosity is 5 mPa·s or more.

It is also preferable that the viscosity of the composition (X) at 40°C is 1 mPa·s or more and 30 mPa·s or less. In this case, no matter what the viscosity of the composition (X) is at room temperature, it is possible to reduce the viscosity by slightly heating the composition (X). Therefore, if the composition (X) is heated, it is possible to mold the composition (X) by the inkjet method. In addition, since the viscosity of the composition (X) can be reduced without significantly heating it, it is possible to make it difficult for the composition of the composition (X) to change due to the volatilization of the components in the composition (X). It is more preferable that the viscosity is 20 mPa·s or less, and even more preferable that the viscosity is 15 mPa·s or less. It is also preferable that the viscosity is 5 mPa·s or more.

Such a low viscosity of composition (X) at 25°C or 40°C can also be achieved by the composition of composition (X) described in detail below.

When the cured product of composition (X) has a thickness dimension of 10 μm, the total light transmittance is preferably 90% or more. In this case, when the cured product is applied to the encapsulant 5 in the light-emitting device 1, the extraction efficiency of the light that passes through the encapsulant 5 and is emitted to the outside can be particularly improved. Such light transmittance of the cured product can also be achieved by the composition of composition (X), which will be described in detail below.

The components contained in composition (X) are described in more detail below.

First, we will explain the polythiol compound (A).

As described above, composition (X) contains polythiol compound (A). Polythiol compound (A) has two or more thiol groups in one molecule. Polythiol compound (A) can make it difficult for a curing reaction to occur in composition (X) during storage of composition (X), thereby improving the storage stability of composition (X).

In addition, since the viscosity of the polythiol compound (A) at 25°C is 2000 mPa·s or less, as described above, the polythiol compound (A) is unlikely to increase the viscosity of the composition (X). The viscosity of the polythiol compound (A) at 25°C is more preferably 1800 mPa·s or less, and even more preferably 1500 mPa·s or less. The lower limit of the viscosity of the polythiol compound (A) at 25°C is not particularly limited, but is, for example, 20 mPa ·s or more. The viscosity in this specification is measured using a rheometer under the condition of a shear rate of 1000 s ^-1 . As the rheometer, for example, a model number DHR-2 manufactured by Anton Paar Japan can be used.

In addition, polythiol compound (A) can reduce the occurrence of oxygen inhibition during the curing reaction of composition (X). Therefore, polythiol compound (A) can make it easier to cure composition (X) in an oxygen-containing atmosphere such as air.

The number of thiol groups in one molecule of the polythiol compound (A) is not particularly limited as long as it is two or more. For example, the polythiol compound (A) can contain at least one compound selected from the group consisting of a bifunctional thiol compound (A11) having two thiol groups in one molecule, a trifunctional thiol compound (A12) having three thiol groups in one molecule, and a tetrafunctional thiol compound (A13) having four thiol groups in one molecule. Of course, the polythiol compound (A) may contain a compound having five or more thiol groups in one molecule.

The thiol group of the polythiol compound (A) may contain any of a primary thiol group, a secondary thiol group, and a tertiary thiol group. When the polythiol compound (A) has, for example, two thiol groups, the polythiol compound (A) may contain a compound having two primary thiol groups, a compound having one primary thiol group and one secondary thiol group, a compound having two secondary thiol groups, a compound having one secondary thiol group and one tertiary thiol group, or a compound having two tertiary thiol groups. It is preferable that the polythiol compound (A) contains a compound having two or more secondary or higher thiol groups. In this case, the polythiol compound (A) can make it more difficult for the viscosity of the composition (X) to increase. This is presumably because in compounds having two or more secondary or higher thiol groups, the steric hindrance around the thiol groups becomes large, making the polythiol compound (A) particularly difficult to react with during storage of the composition (X).

As described above, the polythiol compound (A) can make oxygen inhibition less likely to occur during the curing reaction of the composition (X). In this embodiment, oxygen inhibition means that the polymerization reaction of the acrylic compound (B) is inhibited by the presence of oxygen in the reaction system during the polymerization reaction of the acrylic compound (B). It is believed that the reason why the polythiol compound (A) can make oxygen inhibition less likely to occur is that an ene-thiol reaction occurs between the acrylic compound (B) and the polythiol compound (A) during the curing reaction of the composition (X). Specifically, if oxygen is present during the polymerization reaction of the acrylic compound (B), radical species derived from the acrylic compound (B) during polymerization may react with oxygen to generate peroxides. The generated peroxides may terminate the polymerization reaction by coupling reaction between the peroxides themselves or by reacting with the growing radicals in the polymerization reaction. In this case, it is difficult to smoothly proceed with the polymerization reaction of the acrylic compound (B) in the composition (X) and to sufficiently cure it. Here, the polythiol compound (A) reacts with the peroxide of the acrylic compound (B) generated by the reaction with oxygen to generate a thiyl radical derived from the polythiol compound (A), and the radical species for proceeding with the propagation reaction in the polymerization reaction of the composition (X) can be regenerated. The polythiol compound (A) can also generate a thiyl radical by reacting with the photopolymerization initiator (C). Therefore, it is considered that the composition (X) contains the polythiol compound (A), and thus the deactivation of the radical species necessary for the polymerization reaction can be suppressed even in the presence of oxygen in the polymerization reaction of the composition (X), and the reaction of the composition (X) can be made less likely to be inhibited. Thus, the composition (X) is easily cured even under an atmosphere containing oxygen, such as an air atmosphere. Therefore, when preparing a cured product from the composition (X), the cured product of the composition (X) is easily prepared even under conditions such as an inert gas atmosphere, such as a nitrogen atmosphere, and under conditions that ensure airtightness. Therefore, it can also contribute to reducing the manufacturing cost and the manufacturing man-hours when preparing a cured product from the composition (X). The oxygen-containing atmosphere is, for example, an atmosphere having an oxygen concentration of 150 L/m ³ or more. In addition, the composition (X) is not limited to being cured under an oxygen-containing atmosphere, and may be cured, for example, under an inert gas atmosphere.

The polythiol compound (A) contains at least one compound selected from the group consisting of pentaerythritol tetrakis (3-mercaptobutyrate), 1,4-bis (3-mercaptobutyryloxy) butane, and pentaerythritol tetrakis (mercaptopropionate). Note that the components that can be contained in the polythiol compound (A) are not limited to those mentioned above.

The content of the polythiol compound (A) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is preferably 0.5% by mass or more and 10% by mass or less. When the content of the polythiol compound (A) is 0.5% by mass or more, the viscosity of the composition (X) can be further reduced, and the storage stability of the composition (X) is particularly likely to be obtained. In addition, when the content of the polythiol compound (A) is 10% by mass or less, the curability of the composition (X) can be further improved. The content of the polythiol compound (A) is more preferably 1% by mass or more and 8% by mass or less, and even more preferably 2% by mass or more and 6% by mass or less.

As described above, composition (X) contains an acrylic compound (B).

The viscosity of the entire acrylic compound (B) at 25°C is preferably 50 mPa·s or less. In this case, the acrylic compound (B) can contribute to lowering the viscosity of the composition (X). The viscosity of the entire acrylic compound (B) is more preferably 30 mPa·s or less, and even more preferably 20 mPa·s or less. The viscosity of the entire acrylic compound (B) is, for example, 3 mPa·s or more.

It is also preferable that the viscosity of the entire acrylic compound (B) at 40°C is 50 mPa·s or less. In this case, the acrylic compound (B) can particularly reduce the viscosity of the composition (X) when heated. It is more preferable that the viscosity of the entire acrylic compound (B) is 30 mPa·s or less, and particularly preferable that the viscosity is 20 mPa·s or less. In addition, the viscosity of the entire acrylic compound (B) is, for example, 3 mPa·s or more.

The following describes the compounds that the acrylic compound (B) may contain.

The acrylic compound (B) has one or more (meth)acryloyl groups in one molecule. That is, the acrylic compound (B) includes a polyfunctional (meth)acrylic compound (B10) having two or more (meth)acryloyl groups in one molecule, and a monofunctional (meth)acrylic compound (B20) having only one (meth)acryloyl group in one molecule. Note that "(meth)acryl" means at least one of "acryl" and "methacryl". In addition, in the acrylic compound (B), a compound having one or more acryloyl groups in one molecule is also called compound (B1), and a compound having one or more methacryloyl groups in one molecule is also called compound (B2). Compound (B1) and compound (B2) can be included in either the polyfunctional (meth)acrylic compound (B10) or the monofunctional (meth)acrylic compound (B20).

The acrylic compound (B) preferably contains a compound (B1) and a compound (B2), and the mass ratio of the compound (B1) to the compound (B2) is preferably 1 or more. In this case, when the composition (X) is cured, the curability of the composition (X) can be further improved.

It is preferable that the acrylic compound (B) contains a polyfunctional (meth)acrylic compound (B10). In this case, the polyfunctional (meth)acrylic compound (B10) can increase the glass transition temperature of the cured product of the composition (X), and therefore the heat resistance of the cured product can be improved. The amount of the polyfunctional (meth)acrylic compound (B10) is, for example, 50% by mass or more and 100% by mass or less based on the total amount of the acrylic compound (B). The acrylic compound (B) may contain only the polyfunctional (meth)acrylic compound (B10).

Examples of polyfunctional (meth)acrylic compounds (B10) include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol oligoacrylate, diethylene glycol diacrylate, 1,6-hexanediol oligoacrylate, neopentyl glycol diacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, cyclohexane dimethanol diacrylate, tricyclodecane dimethanol diacrylate, bisphenol A polyethoxy diacrylate, bisphenol F polyethoxy diacrylate, pentatriestrol tetraacrylate, propoxylated (2) neopentyl glycol diacrylate, trimethylolpropane triacrylate, tris(2-hydroxyethyl) Isocyanurate triacrylate, pentaerythritol triacrylate, ethoxylated (3) trimethylolpropane triacrylate, propoxylated (3) glyceryl triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated (4) pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, 2-(2-ethoxyethoxy)ethyl acrylate, hexadiol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, tripropylene glycol triacrylate, bispentaerythritol hexaacrylate, ethylene glycol diacrylate, 1,6-hexanediol diacrylate, ethoxylated 1,6-hexanediol diacrylate acrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,9-nonanediol diacrylate, tetraethylene glycol diacrylate, 2-n-butyl-2-ethyl-1,3-propanediol diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, hydroxypivalic acid trimethylolpropane triacrylate, ethoxylated phosphoric acid triacrylate, ethoxylated tripropylene glycol diacrylate, neopentyl glycol modified trimethylolpropane diacrylate, stearic acid modified pentaerythritol diacrylate, tetramethylolpropane triacrylate, tetramethylolmethane triacrylate, caprolactone modified trimethylolpropane triacrylate, glyceryl propoxylate It contains at least one compound selected from the group consisting of triacrylate, tetramethylolmethane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, neopentyl glycol oligoacrylate, trimethylolpropane oligoacrylate, pentaerythritol oligoacrylate, ethoxylated neopentyl glycol di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

The acrylic equivalent of the polyfunctional (meth)acrylic compound (B10) is preferably 150 g/eq or less, and more preferably 90 g/eq or more and 150 g/eq or less. The weight average molecular weight of the polyfunctional (meth)acrylic compound (B10) is, for example, 100 or more and 1000 or less, and more preferably 200 or more and 800 or less.

The polyfunctional (meth)acrylic compound (B10) may contain a compound having at least one of a benzene ring, an alicyclic ring, and a polar group. The polar group is, for example, at least one of an OH group and an NHCO group. In this case, the shrinkage when the composition (X) is cured can be particularly reduced. Furthermore, the adhesion between the cured product and a member made of an inorganic material can be increased. The polyfunctional (meth)acrylic compound (B10) may contain at least one compound selected from the group consisting of tricyclodecane dimethanol diacrylate, bisphenol A polyethoxy diacrylate, bisphenol F polyethoxy diacrylate, trimethylolpropane triacrylate, and pentatriestrol tetraacrylate. These compounds can particularly reduce the shrinkage when the composition (X) is cured. Furthermore, these compounds can also increase the adhesion between the cured product and a member made of an inorganic material.

It is particularly preferable that the polyfunctional (meth)acrylic compound (B10) contains a compound (B101) having the structure shown in the following formula (1).

CH ₂ =CR ¹ -COO-(R ³ -O) _n -CO-CR ² =CH ₂ ...(1)
In formula (1), ^R1 and ^R2 each represent a hydrogen atom or a methyl group, n represents an integer of 1 or more, and ^R3 represents an alkylene group having 3 or more carbon atoms. When n is 2 or more, Multiple ^R3 's may be the same or different.

Compound (B101) has a structure shown in formula (1), and in particular, the carbon number of R ³ in formula (1) is 3 or more, so that the affinity of the sealing material 5 with water is not easily increased. Therefore, the light-emitting element 4 is not easily deteriorated by water. The carbon number of R ³ is, for example, 3 or more and 15 or less. In addition, compound (B101) has a structure shown in formula (1), and in particular, has two (meth)acryloyl groups in one molecule, so that the glass transition temperature of the cured product can be increased, and therefore the heat resistance of the cured product can be increased. In addition, n in formula (1) is, for example, an integer of 1 to 12.

The percentage of compound (B101) relative to acrylic compound (B) is preferably 50% by mass or more. In this case, it is difficult to increase the affinity of the cured product for water. The percentage of compound (B101) relative to acrylic compound (B) is, for example, 100% by mass or less, or 95% by mass or less, and preferably 80% by mass or less.

It is preferable that the compound (B101) contains a compound (B102) having a boiling point of 270°C or higher. That is, it is preferable that the acrylic compound (B) contains a compound (B102) having a structure shown in formula (1) and a boiling point of 270°C or higher. In this case, the acrylic compound (B) is unlikely to volatilize from the composition (X) during storage of the composition (X) and when the composition (X) is heated. Therefore, the storage stability of the composition (X) is unlikely to be impaired. In addition, even if the compound (A12) remains unreacted in the cured product of the composition (X), outgassing due to the compound (B102) is unlikely to occur from the cured product. Therefore, voids due to outgassing are unlikely to occur in the light-emitting device 1. If there are voids in the light-emitting device 1, moisture may penetrate into the light-emitting element 4 through the voids, but if voids are unlikely to occur, moisture is unlikely to penetrate into the light-emitting element 4. The boiling point is the boiling point under normal pressure obtained by converting the boiling point under reduced pressure, and is determined, for example, by the method shown in Science of Petroleum, Vol. II. P. 1281 (1938). The boiling point of compound (B102) is preferably 280°C or higher.

The percentage of the compound (B102) relative to the acrylic compound (B) is preferably 50% by mass or more. In this case, the storage stability of the composition (X) is effectively increased, outgassing from the sealant 5 is effectively reduced, and the affinity of the sealant 5 for water is not particularly increased. The percentage of the compound (B102) relative to the acrylic compound (B) is, for example, 100% by mass or less, or 95% by mass or less, and preferably 80% by mass or less.

The viscosity of compound (B102) at 25°C is preferably 25 mPa·s or less. In this case, compound (B102) can reduce the viscosity of composition (X). The viscosity of compound (B102) at 25°C is more preferably 25 mPa·s or less, even more preferably 20 mPa·s or less, and particularly preferably 15 mPa·s or less. The viscosity of compound (B102) at 25°C is, for example, 1 mPa·s or more, preferably 3 mPa·s or more, and even more preferably 5 mPa·s or more.

The compound (B102) contains at least one compound selected from the group consisting of, for example, di(meth)acrylic acid esters of alkylene glycols, di(meth)acrylic acid esters of polyalkylene glycols, and di(meth)acrylic acid esters of alkylene oxide-modified alkylene glycols.

The di(meth)acrylic acid ester of alkylene glycol is a compound in which n is 1 in formula (1). In this case, the carbon number of R ³ in formula (1) is preferably 4 to 12. R ³ may be linear or branched. In particular, the di(meth)acrylic acid ester of alkylene glycol preferably contains at least one compound selected from the group consisting of 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and 1,12-dodecanediol dimethacrylate. Examples of di(meth)acrylic acid esters of alkylene glycol include SR213 manufactured by Sartomer, V195 manufactured by Osaka Organic Chemical Industry Co., Ltd., SR212 manufactured by Sartomer, SR247 manufactured by Sartomer, Light Acrylate NP-A manufactured by Kyoei Chemical Industry Co., Ltd., SR238NS manufactured by Sartomer, V230 manufactured by Osaka Organic Chemical Industry Co., Ltd., HDDA manufactured by Daicel Corporation, 1,6HX-A manufactured by Kyoei Chemical Industry Co., Ltd., V260 manufactured by Osaka Organic Chemical Industry Co., Ltd., 1,9-ND-A manufactured by Kyoei Chemical Industry Co., Ltd., A-NOD-A manufactured by Shin-Nakamura Chemical Co., Ltd., CD595 manufactured by Sartomer, and L-NOD-A manufactured by Shin-Nakamura Chemical Co., Ltd. It is preferable that the composition contains at least one compound selected from the group consisting of: No. SR214NS, product number BD made by Shin-Nakamura Chemical Co., Ltd., product number SR297 made by Sartomer, product number SR248 made by Sartomer, product name Light Ester NP made by Kyoei Chemical Co., Ltd., product number SR239NS made by Sartomer, product name Light Ester 1,6HX made by Kyoei Chemical Co., Ltd., product number HD-N made by Shin-Nakamura Chemical Co., Ltd., product name Light Ester 1,9ND made by Kyoei Chemical Co., Ltd., product number NOD-N made by Shin-Nakamura Chemical Co., Ltd., product name Light Ester 1,10DC made by Kyoei Chemical Co., Ltd., product number DOD-N made by Shin-Nakamura Chemical Co., Ltd., and product number SR262 made by Sartomer.

The di(meth)acrylic acid ester of polyalkylene glycol is a compound represented by formula (1) in which n is 2 or more. n is, for example, 2 to 10, preferably 2 to 7, more preferably 2 to 6, and even more preferably 2 to 3. The number of carbon atoms in ^R3 is, for example, 2 to
5. The greater the number of carbon atoms, the higher the hydrophobicity of the cured product, and the less moisture is permeable through the sealing material 5. The di(meth)acrylic acid ester of polyalkylene glycol preferably contains at least one compound selected from the group consisting of diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, hexaethylene glycol dimethacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, and tritetramethylene glycol diacrylate. In addition, examples of the di(meth)acrylic acid ester of polyalkylene glycol include, in particular, SR230 manufactured by Sartomer, SR508NS manufactured by Sartomer, DPGDA manufactured by Daicel, SR306NS manufactured by Sartomer, TPGDA manufactured by Daicel, V310HP manufactured by Osaka Organic Chemical Industry Co., Ltd., APG200 manufactured by Shin-Nakamura Chemical Co., Ltd., Light Acrylate PTMGA-250 manufactured by Kyoei Chemical Industry Co., Ltd., and It is preferable that the composition contains at least one compound selected from the group consisting of Sartomer Corporation (product number SR231NS), Kyoei Chemical Industry Co., Ltd. (product name Light Ester 2EG), Kyoei Chemical Industry Co., Ltd. (product number SR205NS), Kyoei Chemical Industry Co., Ltd. (product name Light Ester 3EG), Sartomer Corporation (product number SR210NS), Kyoei Chemical Industry Co., Ltd. (product name Light Ester 4EG), Mitsubishi Chemical Corporation (product name Acrylatester HX), and Shin-Nakamura Chemical Co., Ltd. (product number 3PG).

The di(meth)acrylic acid ester of alkylene oxide modified alkylene glycol contains, for example, propylene oxide modified neopentyl glycol. The di(meth)acrylic acid ester of alkylene oxide modified alkylene glycol contains, for example, EBECRYL145 manufactured by Daicel Corporation.

It is preferable that the percentage of components in the acrylic compound (B) having a boiling point of 270°C or higher is 80% by mass or more. When the acrylic compound (B) contains the compound (B102), it is preferable that the percentage of components in the acrylic compound (B) having a boiling point of 270°C or higher, including the compound (B102), is 80% by mass or more. In this case, the storage stability of the composition (X) is particularly unlikely to be impaired, and outgassing is particularly unlikely to occur from the cured product. It is even more preferable that the percentage of components in the acrylic compound (B) having a boiling point of 280°C or higher is 80% by mass or more.

Compound (B101) may contain a compound (B103) other than compound (B102).

The polyfunctional (meth)acrylic compound (B10) may contain a compound (B104) having three or more (meth)acryloyl groups in one molecule. That is, the acrylic compound (B) may contain the compound (B104). In this case, the compound (B104) may contain at least one selected from the group consisting of, for example, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate. When the acrylic compound (B) contains the compound (B104), the compound (B104) can particularly increase the glass transition temperature of the cured product, and therefore, can particularly increase the heat resistance of the cured product.

When the acrylic compound (B) contains the compound (B104), the percentage of the compound (B104) relative to the acrylic compound (B) is preferably greater than 0% by mass and less than or equal to 25% by mass. The percentage of the compound (B104) is more preferably 10% by mass or more. In this case, the glass transition temperature of the cured product can be particularly increased. Furthermore, when the compound (B104) is 25% by mass or less, the viscosity of the composition (X) is less likely to increase due to the compound (B104). When the percentage of the compound (B104) is 20% by mass or less, the viscosity of the composition (X) is particularly less likely to increase.

When the acrylic compound (B) contains a compound (B101) having a structure represented by formula (1), it is preferable that the compound (B101) does not contain a compound in which the value of n in formula (1) is 5 or more. When (R ³ -O) _n is a polyethylene glycol skeleton, it is particularly preferable that the compound in which the value of n in formula (1) is greater than 5 is not contained. Even when the compound (B101) contains a compound in which the value of n in formula (1) is greater than 5, the percentage of the compound in which the value of n in formula (1) is greater than 5 relative to the acrylic compound (B) is preferably 20 mass % or less. Also, even when the compound (B101) contains a compound in which the value of n in formula (1) is greater than 5, it is preferable that the compound (B101) does not contain a compound in which the value of n is greater than 9, and more preferably does not contain a compound in which the value of n is greater than 7. In these cases, the viscosity increase of the composition (X) is particularly unlikely to occur.

As described above, the acrylic compound (B) can contain a monofunctional (meth)acrylic compound (B20). The monofunctional (meth)acrylic compound (B20) can suppress the shrinkage of the composition (X) during curing. In addition, the monofunctional (meth)acrylic compound (B20) can contribute to reducing the viscosity of the composition (X). When the acrylic compound (B) contains the monofunctional (meth)acrylic compound (B20), the percentage of the monofunctional (meth)acrylic compound (B20) relative to the total amount of the acrylic compound (B) is preferably greater than 0% by mass and less than or equal to 70% by mass. If the percentage of the monofunctional (meth)acrylic compound (B20) is greater than 0% by mass, the monofunctional (meth)acrylic compound (B20) can suppress the shrinkage of the composition (X) during curing. It is even more preferable if the percentage of the monofunctional (meth)acrylic compound (B20) is 5% by mass or more. If the percentage of the monofunctional (meth)acrylic compound (B20) is 70% by mass or less, outgassing due to the monofunctional (meth)acrylic compound (B20) is unlikely to occur from the composition (X) and the cured product. In addition, if the amount of the monofunctional (meth)acrylic compound (B20) is 70% by mass or less, the amount of the polyfunctional component in the acrylic compound (B) can be secured, and the heat resistance of the cured product can be particularly improved by the polyfunctional component. It is more preferable that the percentage of the monofunctional (meth)acrylic compound (B20) is 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less.

Monofunctional (meth)acrylic compounds (B20) include, for example, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-tertiarybutylcyclohexyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isooctyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3 -Methoxybutyl (meth)acrylate, ethoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydixylethyl (meth)acrylate, ethyl diglycol (meth)acrylate, cyclic trimethylolpropane formal mono(meth)acrylate, imide (meth)acrylate, isoamyl (meth)acrylate, ethoxylated succinic acid (meth)acrylate, trifluoroethyl (meth)acrylate, ω-carboxypolycaprolactone mono(meth)acrylate, cyclohexyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, stearyl (meth)acrylate, diethylene glycol mono Butyl ether (meth)acrylate, lauryl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, octyl/decyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate, ethoxylated (4) nonylphenol (meth)acrylate, methoxypolyethylene glycol (350) mono(meth)acrylate, methoxypolyethylene glycol (550) mono(meth)acrylate, phenoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate It contains at least one compound selected from the group consisting of caprolactone-modified tetrahydrofurfuryl (meth)acrylate, tribromophenyl (meth)acrylate, ethoxylated tribromophenyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, an ethylene oxide adduct of 2-phenoxyethyl (meth)acrylate, acryloylmorpholine, a propylene oxide adduct of 2-phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-methacryloyloxymethylcyclohexene oxide, and 3-(meth)acryloyloxymethylcyclohexene oxide.

The monofunctional (meth)acrylic compound (B20) preferably contains a compound having an alicyclic structure. The compound having an alicyclic structure contains at least one compound selected from the group consisting of, for example, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and 4-tert-butylcyclohexyl (meth)acrylate.

It is also preferable that the monofunctional (meth)acrylic compound (B20) contains a compound (B201) represented by the following formula (10). In this case, the viscosity of the composition (X) is easily reduced, and the sealing material 5 made from the composition (X) is easily provided with adhesion to inorganic material members such as the passivation layer 6. In addition, the compound (B201) has a low viscosity but is not easily volatilized. Therefore, even if the composition (X) is stored, the composition (X) is not easily changed in composition due to the volatilization of the monofunctional (meth)acrylic compound (B20).

In formula (10), R ⁰ is H or a methyl group. X is a single bond or a divalent hydrocarbon group. Each of ^{R 1} to R ¹¹ is H, an alkyl group or -R ¹² -OH, R ¹² is an alkylene group, and at least one of R ¹ to R ¹¹ is an alkyl group or -R ¹² -OH. R ¹ to R ¹¹ are not chemically bonded to each other.

When X is a divalent hydrocarbon group, the carbon number of X is preferably 1 to 5, more preferably 1 to 3. The divalent hydrocarbon group is, for example, a methylene group, an ethylene group, or a propylene group. It is particularly preferable that X is a single bond or a methylene group. In this case, the compound (B201) has the advantages of a small molecular weight and low viscosity.

When at least one of R ¹ to R ¹¹ is an alkyl group, the number of carbon atoms of the alkyl group is preferably 1 or more and 8 or less. The alkyl group is, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group. The alkyl group may be linear or branched. That is, for example, when the alkyl group is a butyl group, the butyl group may be a t-butyl group, a n-butyl group, or a sec-butyl group. When the alkyl group is a hexyl group, the hexyl group may be a t-hexyl group, a n-hexyl group, or a sec-hexyl group. When the alkyl group is an octyl group, the octyl group may be, for example, a t-octyl group. It is particularly preferable that the alkyl group is a methyl group or a t-butyl group. In this case, there is an advantage that the compound (A21) has a small molecular weight and a low viscosity.

In formula (10), it is preferable that an alkyl group or -R ¹² -OH is connected only to the 4-position of the cyclohexane ring. That is, it is preferable that at least one of R ⁶ and R ⁷ among R ¹ to R ¹¹ is an alkyl group or -R ¹² -OH, and the remaining ones are each H. It is particularly preferable that only R ⁶ among R ¹ to R ¹¹ is an alkyl group or -R ¹² -OH, and the remaining ones are each H. In this case, the compound shown in formula (10) can have good reactivity and is particularly likely to impart adhesion to the sealing material 5 with inorganic material members. This is thought to be because the cyclohexane ring in the compound shown in formula (10) has a boat-type conformation, and the bulky alkyl group or -R ¹² -OH at the 4-position is likely to be located in a pseudo-equatorial position. It is thought that the reactivity of the (meth)acryloyl group in the compound shown in formula (10) is enhanced by the compound shown in formula (10) having such a structure. Furthermore, when the compound represented by formula (10) has such a structure, the compound represented by formula (10) can increase the free volume in the sealing material 5. Therefore, it is considered that the interfacial free energy between the sealing material 5 and the member made of an inorganic material is likely to be small, and therefore the adhesion between the sealing material 5 and the member made of an inorganic material is likely to be high. The more bulky the alkyl group or -R ¹² -OH is, the more likely the alkyl group or -R ¹² -OH is to be located in a pseudo-equatorial position. From this viewpoint, the more carbon atoms the alkyl group or -R ¹² -OH has, the more preferable it is, and it is also preferable that the alkyl group or -R ¹² -OH has a branch. For example, it is preferable that the alkyl group or -R ¹² has a t-butyl group.

In formula (10), it is also preferred that an alkyl group or -R ¹² -OH is connected only to each of the 3-position and 5-position of the cyclohexane ring. That is, it is preferred that, among R ¹ to R ¹¹ , at least one of R ⁴ and R ⁵ is an alkyl group or -R ¹² -OH, at least one of R ⁸ and R ⁹ is an alkyl group or -R ¹² -OH, and the remaining groups are each H. It is more preferred that, among R ¹ to R ¹¹ , at least one of R ⁴ and R ⁵ is an alkyl group or -R ¹² -OH, at least one of R ⁸ and R ⁹ is an alkyl group or -R ¹² -OH, and the remaining groups are each H. It is also more preferred that, among ^{R 1} to R ¹¹ , at least one of R ⁴ and R ⁵ is an alkyl group or -R ¹² -OH, at least one of R ⁸ and R ⁹ is an alkyl group or -R ¹² -OH, and the remaining groups are each H. In this case, too, the compound represented by formula (10) can have good reactivity, and is particularly likely to impart adhesion to the sealing material 5 with inorganic material members. This is believed to be because the cyclohexane ring in the compound represented by formula (10) has a boat-type conformation, and the bulky alkyl group or -R ¹² -OH at each of the 3-position and 5-position is likely to be located at a pseudo-equatorial position. For this reason, similar to the case where an alkyl group or -R ¹² -OH is connected only to the 4-position of the cyclohexane ring, it is believed that the reactivity of the (meth)acryloyl group in the compound represented by formula (10) is enhanced, and the adhesion between the sealing material 5 and inorganic material members is likely to be enhanced. The bulkier the alkyl group or -R ¹² -OH, the more likely the alkyl group or -R ¹² -OH is to be located at a pseudo-equatorial position. From this viewpoint, the more carbon atoms the alkyl group or -R ¹² -OH has, the more preferable it is, and it is also preferable that the alkyl group or -R ¹² -OH has a branch. For example, it is preferred that the alkyl group or --R ¹² has a t-butyl group.

When at least one of R ¹ to R ¹¹ is -R ¹² -OH, the carbon number of R ¹² is preferably 1 to 5, and more preferably 1 to 3. R ¹² is, for example, a methylene group, an ethylene group, or a propylene group. It is particularly preferable that R ¹² is a methylene group. In this case, the compound (B201) has the advantages of a small molecular weight and low viscosity.

In formula (10), it is particularly preferred that each of R ¹ to R ¹¹ is H or an alkyl group, and at least one of R ¹ to R ¹¹ is an alkyl group. In this case, the compound represented by formula (10) can have a particularly low viscosity, and therefore composition (X) can have a particularly low viscosity. Therefore, composition (X) can be particularly easily molded by the inkjet method.

It is preferable that compound (B201) contains at least one compound selected from the group consisting of compounds shown in the following formula (11), compounds shown in the following formula (12), and compounds shown in the following formula (13).

It is particularly preferred that the monofunctional (meth)acrylic compound (B20) contains at least one of the compounds shown in formula (11) and formula (12). In this case, it is particularly easy to reduce the viscosity of the composition (X), particularly easy to increase the glass transition temperature of the sealing material 5, and particularly easy to increase the adhesion between the sealing material 5 and the member made of an inorganic material. In addition, the compounds shown in formula (11) and formula (12) are not easily volatilized, and therefore it is easy to improve the storage stability of the composition (X).

It is also preferable that the monofunctional (meth)acrylic compound (B20) contains a compound having a cyclic ether structure. The number of ring members in the cyclic ether structure in the compound having a cyclic ether structure is preferably 3 or more, more preferably 3 to 4. The number of carbon atoms contained in the cyclic ether structure is preferably 2 to 9, more preferably 2 to 6. The compound having a cyclic ether structure contains at least one compound selected from the group consisting of, for example, 3-methacryloyloxymethylcyclohexene oxide and 3-acryloyloxymethylcyclohexene oxide.

It is preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound having a viscosity of 20 mPa·s or less at 25°C. In this case, the viscosity of the composition (X) can be reduced.

It is preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound having a glass transition temperature of 80°C or higher. In this case, the cured product of the composition (X) may have a high glass transition temperature. It is more preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound having a glass transition temperature of 90°C or higher, and even more preferable that it contains at least one compound having a glass transition temperature of 100°C or higher.

It is preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound having a boiling point of 200°C or higher. In this case, the monofunctional (meth)acrylic compound (B20) is less likely to reduce the storage stability of the composition (X). It is even more preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound having a boiling point of 250°C or higher.

It is particularly preferred if the monofunctional (meth)acrylic compound (B20) contains at least one compound having a viscosity of 20 mPa·s or less at 25°C and a glass transition temperature of 80°C or more. It is also preferred if the monofunctional (meth)acrylic compound (B20) contains at least one compound having a viscosity of 20 mPa·s or less at 25°C and a boiling point of 200°C or more. It is also preferred if the monofunctional (meth)acrylic compound (B20) contains at least one compound having a glass transition temperature of 80°C or more and a boiling point of 200°C or more. It is particularly preferred if the monofunctional (meth)acrylic compound (B20) contains at least one compound having a viscosity of 20 mPa·s or less at 25°C, a glass transition temperature of 80°C or more, and a boiling point of 200°C or more.

In particular, it is preferable that the monofunctional (meth)acrylic compound (B20) contains at least one compound selected from the group consisting of isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and 4-tertiarybutylcyclohexyl (meth)acrylate. Isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and 4-tertiarybutylcyclohexyl (meth)acrylate have high glass transition temperatures, low viscosities, and high boiling points, and therefore can particularly enhance the properties of the composition (X) and the curing agent.

It is preferable that the acrylic compound (B) further contains at least one compound selected from the group consisting of a compound (B41) having silicon in the molecular skeleton, a compound (B42) having phosphorus in the molecular skeleton, and a compound (B43) having nitrogen in the molecular skeleton. In this case, the adhesion between the cured product and the sealing material 5 and the inorganic material member such as the passivation layer 6 is improved. For this reason, a gap is unlikely to occur between the sealing material 5 and the inorganic material member, and moisture is unlikely to penetrate into the light-emitting element 4 through this gap. It is particularly preferable that the acrylic compound (B) contains a compound (B43) having nitrogen in the molecular skeleton (hereinafter also referred to as a nitrogen-containing acrylic compound (B43)), and the content of the nitrogen-containing acrylic compound (B43) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is preferably 10 mass% or more. In this case, the adhesion between the cured product and the sealing material 5 and the inorganic material member can be improved, and the curability of the composition (X) can be further improved when the composition (X) is cured. The content of the nitrogen-containing acrylic compound (B43) is more preferably 12% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 35% by mass or less. The compounds (B41), (B42) and (B43) are defined by the type of atoms in the molecular skeleton. Therefore, the compounds contained in each of the polyfunctional (meth)acrylic compound (B10) and the monofunctional (meth)acrylic compound (B20) may overlap with the compounds contained in each of the compounds (B41), (B42) and (B43).

Compound (B41) contains at least one compound selected from the group consisting of, for example, 3-(trimethoxysilyl)propyl acrylate (e.g., product number KBM5103 manufactured by Shin-Etsu Chemical Co., Ltd.) and (meth)acrylic group-containing alkoxysilane oligomer (e.g., product number KR-513 manufactured by Shin-Etsu Chemical Co., Ltd.). However, since the boiling point of 3-(trimethoxysilyl)propyl acrylate is 260°C, when acrylic compound (A) contains 3-(trimethoxysilyl)propyl acrylate, the percentage of 3-(trimethoxysilyl)propyl acrylate relative to acrylic compound (A) must be 10 mass% or less.

Compound (B42) includes, for example, acid phosphooxy (meth)acrylate, such as acid phosphooxy polyoxypropylene glycol monomethacrylate.

The nitrogen-containing acrylic compound (B43) includes, for example, at least one compound selected from the group consisting of acryloylmorpholine, hydroxyethylacrylamide, diethylacrylamide, dimethylaminopropylacrylamide, and pentamethylpiperidyl methacrylate.

When the acrylic compound (B) contains at least one compound selected from the group consisting of the compound (B41), the compound (B42), and the nitrogen-containing acrylic compound (B43), the percentage of the total amount of the compound (B41), the compound (B42), and the nitrogen-containing acrylic compound (B43) relative to the acrylic compound (B) is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 15% by mass or less.

The composition (X) may contain a radical polymerizable compound (G1) other than the acrylic compound (B). The radical polymerizable compound (G1) may contain either one or both of a polyfunctional radical polymerizable compound (G11) having two or more radical polymerizable functional groups in one molecule and a monofunctional radical polymerizable compound (G12) having only one radical polymerizable functional group in one molecule. The amount of the radical polymerizable compound (G1) relative to the total amount of the acrylic compound (B) and the radical polymerizable compound (G1) is, for example, 10 mass% or less. The polyfunctional radical polymerizable compound (G11) may contain at least one compound selected from the group consisting of aromatic urethane oligomers, aliphatic urethane oligomers, epoxy acrylate oligomers, polyester acrylate oligomers, and other special oligomers having two or more ethylenic double bonds in one molecule. Note that the components that the polyfunctional radical polymerizable compound (G11) may contain are not limited to the above. The monofunctional radical polymerizable compound (G12) contains at least one compound selected from the group consisting of, for example, N-vinylformamide, vinylcaprolactam, vinylpyrrolidone, phenylglycidyl ether, p-tert-butylphenylglycidyl ether, butylglycidyl ether, 2-ethylhexylglycidyl ether, allylglycidyl ether, 1,2-butylene oxide, 1,3-butadiene monoxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-vinylcyclohexene oxide, 4-vinylcyclohexene oxide, N-vinylpyrrolidone, and N-vinylcaprolactam. Note that the components that the monofunctional radical polymerizable compound (G12) may contain are not limited to those mentioned above.

The photopolymerization initiator (C) is not particularly limited as long as it is a compound that generates radical species when irradiated with light. The photopolymerization initiator (C) contains at least one compound selected from the group consisting of aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having carbon-halogen bonds, and alkylamine compounds. The amount of the photopolymerization initiator (C) relative to 100 parts by mass of the composition (X) is, for example, 1 part by mass or more and 10 parts by mass or less. The amount of the photopolymerization initiator (C) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is, for example, 1% by mass or more and 12% by mass or less.

The photopolymerization initiator (C) preferably contains at least one compound selected from the group consisting of an aminoacetophenone compound (C1) and an acylphosphine oxide compound (C2), and the photopolymerization initiator (C) more preferably contains an aminoacetophenone compound (C1). When the photopolymerization initiator (C) contains an aminoacetophenone compound (C1), the content of the aminoacetophenone compound (C1) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is preferably 1.0% by mass or more and 15% by mass or less. In this case, when the composition (X) is irradiated with light to cure it, the curability of the composition (X) can be further improved. In particular, when the content of the aminoacetophenone compound (C1) is 1.0% by mass or more, the generation of outgassing derived from the uncured acrylic compound (B) can be further suppressed. In addition, when the content is 100% by mass or less, the storage stability of the composition (X) can be well maintained. The content of the aminoacetophenone compound (C1) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is more preferably 1.5% by mass or more and 10% by mass or less, and even more preferably 2% by mass or more and 5% by mass or less.

Examples of aminoacetophenone compounds (C1) include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone.

Examples of acylphosphine oxides (C2) include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)diphenylphosphine oxide, etc.

It is also preferable that the photopolymerization initiator (C) contains a sensitizer (D) as part of the photopolymerization initiator (C). The sensitizer (D) can promote the radical generation reaction of the photopolymerization initiator (C), thereby improving the reactivity of the radical polymerization and improving the crosslinking density.

The content of sensitizer (D) in composition (X) is, for example, 0.1 parts by mass or more and 5 parts by mass or less, and preferably 0.1 parts by mass or more and 3 parts by mass or less, per 100 parts by mass of the solid content of composition (X). If the content of the sensitizer is within such a range, composition (X) can be more easily cured in an oxygen-containing atmosphere.

Sensitizers (D) include, for example, thioxanthone-based sensitizers such as thioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, and 2,4-diethylthioxanthone; anthracene-based sensitizers such as 9,10-dibutoxyanthracene and 9-hydroxymethylanthracene; anthraquinone-based sensitizers such as anthraquinone, 1,2-dihydroxyanthraquinone, and 2-ethylanthraquinone; 1,4-diethoxynaphthalene; p-dimethylamine; The photopolymerization initiator (C) may contain at least one compound selected from the group consisting of acetophenone-based sensitizers such as p-dimethylaminobenzophenone, p-diethylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and the like; benzophenone-based sensitizers such as p-dimethylaminobenzaldehyde, p-diethylaminobenzaldehyde, and the like; and benzaldehyde-based sensitizers such as p-dimethylaminobenzaldehyde, p-diethylaminobenzaldehyde, and the like. The sensitizer (D) preferably contains a thioxanthone-based sensitizer (D1). The content of the thioxanthone-based sensitizer (D1) relative to the photopolymerization initiator (C) is preferably 1.0% by mass or more and 90% by mass or less. In this case, the curability of the composition (X) can be further improved. The content of the thioxanthone sensitizer (D1) relative to the photopolymerization initiator (C) is more preferably 10% by mass or more and 80% by mass or less, and even more preferably 20% by mass or more and 70% by mass or less. In particular, when the photopolymerization initiator (C) contains an aminoacetophenone compound (C1), the content of the thioxanthone sensitizer (D1) relative to the aminoacetophenone compound (C1) is preferably 1.0% by mass or more and 100% by mass or less. In this case, the effect of the sensitizer (D) is particularly pronounced.

The composition (X) may contain a polymerization accelerator in addition to the photopolymerization initiator (C). The polymerization accelerator contains, for example, an amine compound such as ethyl p-dimethylaminobenzoate, 2-ethylhexyl p-dimethylaminobenzoate, methyl p-dimethylaminobenzoate, 2-dimethylaminoethyl benzoate, or butoxyethyl p-dimethylaminobenzoate.

The composition (X) may contain a polymerization inhibitor. In particular, when the polythiol compound (A) in the composition (X) has a primary thiol group, the storage stability of the composition (X) can be further improved. The content of the polymerization inhibitor relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is preferably 0.5% by mass or more and 5% by mass or less. Examples of the polymerization inhibitor include at least one compound selected from the group consisting of hydroquinone, hydroquinone monomethyl ether, 1,4-benzoquinone, tert-butylhydroquinone, and 4-tert-butylpyrocatechol.

It is preferable that the composition (X) further contains a moisture absorbent (E). In this case, even if the cured product of the composition (X) is exposed to moisture, the moisture absorbent (E) absorbs the moisture, so that the cured product and the light-emitting element 4 in the light-emitting device 1 are less likely to deteriorate. The average particle size of the moisture absorbent (E) is preferably 10 nm or more and 200 nm or less. In this case, the cured product can have high transparency.

The moisture absorbent (E) is preferably an inorganic particle having moisture absorbing properties, and preferably contains at least one component selected from the group consisting of zeolite particles, silica gel particles, calcium chloride particles, and titanium oxide nanotube particles. It is particularly preferable that the moisture absorbent (E) contains zeolite particles.

Zeolite particles with an average particle size of 200 nm or less can be produced, for example, by crushing general industrial zeolite. When producing zeolite particles, the zeolite may be crushed and then crystallized by hydrothermal synthesis or the like, in which case the zeolite particles can have particularly high hygroscopicity. Examples of methods for producing such zeolite particles are disclosed in JP 2016-69266 A, JP 2013-049602 A, and the like.

The zeolite particles preferably contain sodium ions, and therefore the zeolite particles are preferably produced using a zeolite containing sodium ions as a raw material. It is more preferable to use at least one type of zeolite selected from the group consisting of A-type zeolite, X-type zeolite, and Y-type zeolite as a raw material among the zeolites containing sodium ions. It is particularly preferable to produce the zeolite particles using 4A-type zeolite as a raw material among the A-type zeolites. In these cases, the zeolite particles have a crystal structure suitable for adsorbing moisture.

The average particle size of the moisture absorbent (E) is preferably 10 nm or more and 200 nm or less. If the average particle size is 200 nm or less, the cured product can have particularly high transparency. If the average particle size is 10 nm or more, the moisture absorbent (E) can maintain good moisture absorption. The average particle size is the median diameter calculated from the measurement results by dynamic light scattering, that is, the cumulative 50% diameter (D50). As a measuring device, the Nanotrac Wave series of Microtrac Bell Co., Ltd. can be used. The average particle size of the moisture absorbent (E) is more preferably 150 nm or less, even more preferably 100 nm or less, and particularly preferably 70 nm or less. The average particle size of the moisture absorbent (E) is preferably 20 nm or more, and more preferably 50 nm or more. In this case, the cured product can have particularly good transparency and moisture absorption.

The cumulative 90% diameter (D90) of the moisture absorbent (E) is preferably 300 nm or less, and more preferably 100 nm or less. In this case, the cured product can have particularly high transparency.

When the composition (X) contains the moisture absorbent (E), the ratio of the moisture absorbent (E) to the total amount of the composition (X) is preferably 1% by mass or more and 20% by mass or less. If the ratio of the moisture absorbent (E) is 1% by mass or more, the cured product can have particularly high moisture absorption. If the ratio of the moisture absorbent (E) is 20% by mass or less, the viscosity of the composition (X) can be particularly reduced, and the composition (X) can have a sufficiently low viscosity to be applicable by the inkjet method. The ratio of the moisture absorbent (E) is more preferably 3% by mass or more, and particularly preferably 5% by mass or more. The ratio of the moisture absorbent (E) is more preferably 15% by mass or less, and particularly preferably 13% by mass or less.

The composition (X) may further contain an inorganic filler other than the moisture absorbent (E). In particular, the composition (E) preferably contains nano-sized high refractive index particles. Examples of high refractive index particles include zirconia particles. When the composition (X) contains high refractive index particles, the refractive index of the cured product can be increased while maintaining good transparency of the cured product. Therefore, when the cured product of the composition (X) is applied to the encapsulant 5 in the light-emitting device 1, the extraction efficiency of the light that passes through the encapsulant 5 and is emitted to the outside can be improved. The average particle size of the high refractive index particles is preferably in the range of 5 nm to 30 nm, and more preferably in the range of 10 nm to 20 nm.

The proportion of high refractive index particles in composition (X) is appropriately designed so that the cured product has the desired refractive index. In particular, it is preferable that the high refractive index particles are contained in composition (X) so that the refractive index of the cured product is in the range of 1.45 or more and less than 1.55. In this case, the light extraction efficiency of the light emitting device 1 is particularly improved.

The composition (X) may contain a dispersant (F). The dispersant (F) can improve the dispersibility of the components in the composition (X). Therefore, the dispersant (F) can prevent the increase in viscosity and the decrease in storage stability of the composition (X) caused by the polythiol compound (A) from occurring. The dispersant (F) is a surfactant that can be adsorbed to particles. In addition, when the composition (X) contains an adsorbent (E), the dispersant (F) can disperse the adsorbent (E) well, so that the transparency of the cured product and the sealant 5 is not easily reduced by the adsorbent (E) even though the cured product and the sealant 5 contain the adsorbent (E). In addition, the dispersant (F) can effectively suppress the aggregation of the adsorbent (E) during storage of the composition (X). Therefore, the storage stability of the composition (X) is not easily reduced by the adsorbent (E).

The dispersant (F) has an adsorption group (generally also called an anchor) that can be adsorbed to a particle, and a molecular skeleton (generally also called a tail) that attaches to the particle by adsorbing the adsorption group to the particle. The dispersant (F) contains at least one component selected from the group consisting of, for example, an acrylic dispersant whose tail is an acrylic molecular chain, a urethane dispersant whose tail is a urethane molecular chain, and a polyester dispersant whose tail is a polyester molecular chain. The adsorption group includes, for example, at least one of a basic polar functional group and an acidic polar functional group. The basic polar functional group includes, for example, at least one group selected from the group consisting of an amino group, an imino group, an amide group, an imide group, and a nitrogen-containing heterocyclic group. The acidic polar functional group includes, for example, at least one group selected from the group consisting of a carboxyl group and a phosphate group. The dispersant (F) can contain at least one compound selected from the group consisting of, for example, the Solsperse series manufactured by Nippon Louvre Resol Co., Ltd., the DISPERBYK series manufactured by BYK Japan Co., Ltd., and the AJISPER series manufactured by Ajinomoto Fine-Techno Co., Ltd.

When the composition (X) contains a moisture absorbent (E), the amount of the dispersant (F) relative to 100 parts by mass of the moisture absorbent (E) is preferably 5 parts by mass or more and 60 parts by mass or less. When the amount of the dispersant (F) is 5 parts by mass or more, the function of the dispersant (F) can be effectively expressed, and when the amount is 60 parts by mass or less, the free molecules of the dispersant (F) in the cured product (sealant) of the composition (X) can be prevented from impairing the adhesion between the sealant and the inorganic material member. In addition, the amount of the dispersant (D) is more preferably 15 parts by mass or more, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

Dispersant (F) is blended with composition (X) as necessary. For example, when composition (X) does not contain adsorbent (E) or when adsorbent (E) is one that does not easily reduce dispersibility, composition (X) has storage stability even without containing a dispersant.

It is preferable that the composition (X) does not contain a solvent or that the solvent content is 1% by mass or less. In this case, when preparing a cured product from the composition (X), it is not necessary to dry the composition (X) to volatilize the solvent. Therefore, even if the composition (X) contains the polythiol compound (A), outgassing is unlikely to occur from the composition (X) and the cured product. In addition, the storage stability of the composition (X) is further improved. And, by preparing a sealant from the composition (X), it is possible to realize that the sealant 5 is substantially free of solvent. Therefore, in the light-emitting device 1, it is possible to make it difficult for voids due to outgassing generated from the sealant 5 to occur. The solvent content is more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less. It is particularly preferable that the composition (X) does not contain a solvent or contains only a solvent that is inevitably mixed in.

Composition (X) can be prepared by mixing the above-mentioned components. Composition (X) is preferably liquid at 25°C.

2. Structure of the Light-Emitting Device Next, the structure of the light-emitting device 1 will be described. The light-emitting device 1 includes a light-emitting element 4 and a sealing material 5 that covers the light-emitting element 4. The sealing material 5 may cover the light-emitting element 4 in a state of direct contact with the light-emitting element 4, or may cover the light-emitting element 4 with some layer interposed between the sealing material 5 and the light-emitting element 4. The light-emitting device 1 may be, for example, a lighting device or a display device 10 (display).

The light-emitting element 4 includes, for example, a light-emitting diode. The light-emitting diode includes, for example, at least one of an organic EL element (organic light-emitting diode) and a micro light-emitting diode. When the light-emitting element 4 includes an organic light-emitting diode, the light-emitting device 1 including the light-emitting element 4 is, for example, an organic EL display. When the light-emitting element 4 includes a micro light-emitting diode, the light-emitting device 1 including the light-emitting element 4 is, for example, a micro LED display. Note that EL stands for electroluminescence, and LED stands for light-emitting diode.

The sealing material 5 is preferably a cured product of the composition for sealing light-emitting elements described above.

A first example of the structure of the light-emitting device 1 will be described with reference to FIG. 1. This light-emitting device 1 is a top-emission type. The light-emitting device 1 comprises a support substrate 2, a transparent substrate 3 that faces the support substrate 2 with a gap therebetween, a light-emitting element 4 on the surface of the support substrate 2 that faces the transparent substrate 3, and a sealant 5 that fills between the support substrate 2 and the transparent substrate 3. In addition, in the first example, the light-emitting device 1 comprises a passivation layer 6 that covers the surface of the support substrate 2 that faces the transparent substrate 3 and the light-emitting element 4. That is, the passivation layer 6 is interposed between the light-emitting element 4 and the sealant 5 that covers the light-emitting element 4.

The support substrate 2 is made of, for example, a resin material, but is not limited thereto. The transparent substrate 3 is made of a material having light transmissivity. The transparent substrate 3 is, for example, a glass substrate or a transparent resin substrate. When the light-emitting element 4 includes an organic EL element, the organic EL element includes, for example, a pair of electrodes and an organic light-emitting layer between the electrodes. The organic light-emitting layer includes, for example, a hole injection layer, a hole transport layer, an organic light-emitting layer, and an electron transport layer, and these layers are stacked in the above order. Although only one light-emitting element 4 is shown in FIG. 1, the light-emitting device 1 may include multiple light-emitting elements 4, and the multiple light-emitting elements 4 may form an array on the support substrate 2. The passivation layer 6 is preferably made of silicon nitride or silicon oxide.

A second example of the structure of the light-emitting device 1 will be described with reference to FIG. 2. Elements in FIG. 2 that are common to the first example shown in FIG. 1 are given the same reference numerals as in FIG. 1, and detailed descriptions will be omitted as appropriate. The light-emitting device 1 shown in FIG. 2 is also of a top-emission type. The light-emitting device 1 comprises a support substrate 2, a transparent substrate 3 that faces the support substrate 2 with a gap therebetween, a light-emitting element 4 on the surface of the support substrate 2 that faces the transparent substrate 3, and a sealant 5 that covers the light-emitting element 4.

When the light-emitting element 4 includes an organic EL element, the organic EL element, as in the first example, includes, for example, a pair of electrodes 41, 43 and an organic light-emitting layer 42 between the electrodes 41, 43. The organic light-emitting layer 42 includes, for example, a hole injection layer 421, a hole transport layer 422, an organic light-emitting layer 423, and an electron transport layer 424, and these layers are stacked in the above order.

The light-emitting device 1 includes a plurality of light-emitting elements 4, which form an array 9 (hereinafter referred to as element array 9) on a support substrate 2. The element array 9 also includes a partition 7. The partition 7 is on the support substrate 2 and separates two adjacent light-emitting elements 4. The partition 7 is fabricated, for example, by forming a photosensitive resin material using a photolithography method. The element array 9 also includes connection wiring 8 that electrically connects the electrodes 43 and the electron transport layers 424 of adjacent light-emitting elements 4. The connection wiring 8 is provided on the partition 7.

The light emitting device 1 also includes a passivation layer 6 that covers the light emitting element 4. The passivation layer 6 is preferably made of silicon nitride or silicon oxide. The passivation layer 6 includes a first passivation layer 61 and a second passivation layer 62. The first passivation layer 61 covers the element array 9 while being in direct contact with the element array 9, thereby covering the light emitting element 4. The second passivation layer 62 is disposed on the opposite side of the element array 9 with respect to the first passivation layer 61, and a gap is provided between the second passivation layer 62 and the first passivation layer 61. The sealant 5 is filled between the first passivation layer 61 and the second passivation layer 62. That is, the first passivation layer 61 is interposed between the light emitting element 4 and the sealant 5 that covers the light emitting element 4.

Furthermore, a second sealing material 52 is filled between the second passivation layer 62 and the transparent substrate 3. The second sealing material 52 is made of, for example, a transparent resin material. The material of the second sealing material 52 is not particularly limited. The material of the second sealing material 52 may be the same as or different from the sealing material 5.

The encapsulant 5 in the light-emitting device 1 having the structure exemplified above can be produced from the composition for encapsulating a light-emitting element according to this embodiment. That is, the composition for encapsulating a light-emitting element is used to produce the encapsulant 5 for the light-emitting element 4. In other words, the composition for encapsulating a light-emitting element is preferably a composition for producing an encapsulant, a composition for encapsulating a light-emitting element, or a composition for manufacturing a light-emitting device.

3. Method for Producing Encapsulant and Method for Producing Light-Emitting Device A method for producing the encapsulant 5 using the composition (X) and a method for producing the light-emitting device 1 will be described.

In this embodiment, it is preferable to mold the composition (X) by the inkjet method, and then irradiate the composition (X) with light such as ultraviolet light to harden the composition (X), thereby producing the sealing material 5. In this embodiment, the composition (X) can be applied and molded by the inkjet method.

When applying composition (X) by the inkjet method, if composition (X) has a sufficiently low viscosity at room temperature, for example, if the viscosity at 25°C is 30 mPa·s or less, particularly 15 mPa·s or less, composition (X) can be molded by applying it by the inkjet method without heating.

When composition (X) has the property of being reduced in viscosity by heating, composition (X) may be heated and then applied and molded by an inkjet method. When composition (X) has a viscosity of 30 mPa·s or less, particularly 15 mPa·s or less at 40°C, composition (X) can be reduced in viscosity by simply heating it slightly, and this reduced-viscosity composition (X) can be ejected by an inkjet method. The heating temperature for composition (X) is, for example, 20°C or higher and 50°C or lower.

More specifically, for example, first, a support substrate 2 is prepared. A partition wall is fabricated on one surface of the support substrate 2 by photolithography using, for example, a photosensitive resin material. Next, a plurality of light-emitting elements 4 are provided on one surface of the support substrate 2. The light-emitting elements 4 can be fabricated by an appropriate method such as a vapor deposition method or a coating method. It is particularly preferable to fabricate the light-emitting elements 4 by a coating method such as an inkjet method. In this way, an element array 9 is fabricated on the support substrate 2.

Next, a first passivation layer 61 is provided on the element array 9. The first passivation layer 61 can be produced by a deposition method such as a plasma CVD method.

Next, composition (X) is formed on the first passivation layer 61 by, for example, an inkjet method to produce a coating film. If the inkjet method is used for both the formation of the light-emitting element 4 and the application of composition (X), the manufacturing efficiency of the light-emitting device 1 can be particularly improved. Note that composition (X) may be formed by a method other than the inkjet method, for example, a casting method.

Next, the coating film is irradiated with light to harden it, producing the sealant 5. The thickness of the sealant 5 is, for example, 5 μm or more and 50 μm or less. The wavelength of the light irradiated to the coating film may be appropriately adjusted depending on the composition of the composition (X), and may be, for example, visible light or ultraviolet light. The wavelength of the light irradiated to the coating film is, for example, 385 nm or more. For example, an LED can be used as a light source for irradiating light. When the wavelength of the irradiated light is in this wavelength range, the composition (X) can be hardened particularly efficiently.

As described above, the composition (X) of this embodiment contains the polythiol compound (A), the acrylic compound (B), and the photopolymerization initiator (C), and therefore when the composition (X) is irradiated with light, it can be cured even in an atmosphere that contains oxygen, such as the air atmosphere. Therefore, when producing the sealing material 5 from the composition (X), it is possible to reduce the manufacturing costs and the manufacturing steps.

It is also preferable that the thickness of the sealing material 5 is 4 μm or more and 50 μm or less, and more preferably 4 μm or more and 15 μm or less. As described above, in this embodiment, since small droplets of the composition (X) can be easily formed at high density by the inkjet method, it is easy to realize a thin sealing material 5 of 4 μm or more and 15 μm or less. By thinning the sealing material 5 in this way, tensile stress and compressive stress are less likely to occur in the sealing material 5 within the light-emitting device 1. Therefore, it is easier to realize a flexible light-emitting device 1.

Next, a second passivation layer 62 is provided on the sealing material 5. The second passivation layer 62 can be produced by a deposition method such as plasma CVD.

Next, a curable resin material is applied to one surface of the support substrate 2 so as to cover the second passivation layer 62, and then the transparent substrate 3 is placed on top of this resin material. The transparent substrate 3 is, for example, a glass substrate or a transparent resin substrate.

Next, light is applied from the outside toward the transparent substrate 3. The light passes through the transparent substrate 3 and reaches the curable resin material. This causes the curable resin material to harden, producing the second sealing material 52.

Furthermore, as described above, the sealant 5 made of the cured product of composition (X) has good heat resistance. Therefore, when a passivation layer 6 (second passivation layer 62) is produced on top of the sealant 5 by a deposition method such as plasma CVD, the sealant 5 is unlikely to deteriorate even if the temperature of the sealant 5 rises. Furthermore, the sealant 5 is unlikely to deteriorate even if the temperature of the light-emitting device 1 rises during use of the light-emitting device.

In the above description, it has been explained that the composition for sealing light-emitting elements of this embodiment is particularly suitable for producing a sealing material for sealing light-emitting elements, but the composition (X) can be used to produce various objects formed by the inkjet method. Therefore, the use of the composition (X) is not limited to this, and it may be used for other purposes such as a material for a color resist constituting a color filter, an interlayer insulating material for insulating between ITO electrodes, and an index matching layer for adjusting the reflectance and transmittance of light in a display device. As a specific example, for example, a phosphor may be contained in the composition (X), and a color resist in a color filter may be produced from this composition (X). In this case, it is easy to produce the color resist in the color filter with high density and high accuracy. This color filter can be provided in a display device such as an organic EL display or a micro LED display.

Specific examples of the present invention are presented below. However, the present invention is not limited to these examples.

1. Preparation of Compositions Compositions of the examples and comparative examples were prepared by mixing the components shown in the table below.

The details of the components shown in the table are as follows: The viscosity of each component was measured using a rheometer (manufactured by Anton Paar Japan, model DHR-2) at a temperature of 25° C. and a shear rate of 1000 s ^-1 .

(1) Acrylic Compounds (1-1) Polyfunctional Acrylic Compounds Acrylic compound 1: trimethylolpropane triacrylate, which is a trifunctional acrylic compound, has a viscosity of 106 mPa·s, a glass transition temperature of 62° C., a refractive index of 1.472, and a boiling point of 300° C. or higher, manufactured by Sartomer Corporation, product number SR351S.
Acrylic compound 2: Polyethylene glycol 200 dimethacrylate, a bifunctional methacrylic compound, viscosity 14 mPa·s, manufactured by Shin-Nakamura Chemical Co., Ltd., product name A-200.
Acrylic compound 3: polyethylene glycol 200 diacrylate, a bifunctional acrylic compound, viscosity 17 mPa·s, manufactured by Shin-Nakamura Chemical Co., Ltd., product name 4G.

(1-2) Monofunctional acrylic compound. Acrylic compound 4: isobornyl acrylate, viscosity 8 mPa·s, glass transition temperature 97° C., boiling point 260° C., manufactured by Osaka Organic Chemical Industry Ltd., product name IBXA.
Acrylic compound 5: dicyclopentanyl acrylate, viscosity 13 mPa·s, glass transition temperature 120° C., manufactured by Hitachi Chemical Co., Ltd., product name FA-513AS.
Acrylic compound 6: dicyclopentanyl methacrylate, viscosity 12 mPa·s, glass transition temperature 175° C., manufactured by Hitachi Chemical Co., Ltd., product name FA513M.
Acrylic compound 7: acryloylmorpholine, a nitrogen-containing acrylic compound, having a viscosity of 12 mPa·s and a glass transition temperature of 145° C., manufactured by KJ Chemicals Co., Ltd.
Acrylic compound 8: hydroxyethylacrylamide, a nitrogen-containing compound, having a viscosity of 280 mPa·s and a glass transition temperature of 98°C.

(2) Thiol Compounds Thiol compound 1: Pentaerythritol tetrakis(3-mercaptobutyrate). A tetrafunctional secondary thiol compound having four thiol groups in one molecule. Viscosity 1100 mPa·s (25°C), manufactured by Showa Denko K.K., product name Karenz MT (registered trademark) PE1.
Thiol compound 2: 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. A trifunctional secondary thiol compound having three thiol groups in one molecule. Viscosity 7500 mPa·s (25°C), manufactured by Showa Denko K.K., product name Karenz MT (registered trademark) NR1.
Thiol compound 3: 1,4-bis(3-mercaptobutyryloxy)butane. A bifunctional secondary thiol compound having two thiol groups in one molecule. Viscosity 21 mPa·s (25°C), manufactured by Showa Denko K.K., product name Karenz MT (registered trademark) BD1.
Thiol compound 4: pentaerythritol tetrakis(mercaptopropionate). A tetrafunctional primary thiol compound having four thiol groups in one molecule. Viscosity 430 mPa·s (25°C), manufactured by Sakai Chemical Industry Co. , Ltd.

(3) Polymerization initiator/photopolymerization initiator 1: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, an acylphosphine oxide-based photopolymerization initiator, manufactured by BASF Corporation, product name Irgacure TPO.
Photopolymerization initiator 2: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, an aminoacetophenone-based photopolymerization initiator, manufactured by BASF Corporation, product name Irgacure 907.
Photosensitizer 1: 2,4-diethylthioxanthen-9-one. A thioxanthone-based sensitizer.

(4) Moisture absorbent (4-1) Zeolite particles 1
Zeolite particles 1 are produced by the following method, and have a D50 of 60 nm, a D90 of 110 nm, and a pH of 11.

Zeolite 4A sodium ion powder with an average particle size of 5 μm was prepared as the starting material, and 100 g of this zeolite powder was mixed with 100 g of ion-exchanged water to prepare a slurry.

400 g of zirconia beads with a particle size of 100 μm were added to this slurry, and the zeolite powder in the slurry was pulverized in a bead mill for 3 hours to obtain an average particle size of 120 nm for the Na-based zeolite. The slurry flow rate at this time was 10 kg/h, and the slurry viscosity was 10 mPa·s.

Next, the zirconia beads with a particle size of 100 μm were removed from the slurry and replaced with 400 g of zirconia beads with a particle size of 50 μm. The Na-based zeolite in the slurry was then pulverized for 1 hour using a bead mill pulverizer, resulting in an average particle size of the zeolite powder of 70 nm. The slurry flow rate at this time was 10 kg/h, and the slurry viscosity was 6 mPa·s.

Next, the zirconia beads with a particle size of 50 μm were removed from the slurry and replaced with 450 g of zirconia beads with a particle size of 30 μm. The zeolite powder in the slurry was then pulverized for 1 hour using a bead mill pulverizer, resulting in an average particle size of the zeolite powder of 60 nm. The slurry flow rate at this time was 10 kg/h, and the slurry viscosity was 4 mPa·s.

The slurry was then left to stand at 180°C for 2 to 3 hours to obtain finely pulverized zeolite powder. This zeolite powder was crushed in a mortar and passed through a mesh to adjust the particle size, obtaining zeolite particles 1.

The pH of the zeolite particles was measured as follows: 0.05 g of zeolite particles and 99.95 g of ion-exchanged water were placed in a polyethylene bottle, which was then placed in a thermostatic chamber and heated at 90°C for 24 hours. The pH of the supernatant liquid in the bottle was then measured using a compact pH meter (LAQUAtwin) B-711 manufactured by Horiba, Ltd.

(4-2) Zeolite particles 2
Zeolite particles 2 are produced by the following method, and have a D50 of 150 nm, a D90 of 250 nm, and a pH of 11.

Zeolite 4A sodium ion with an average particle size of 5 μm was prepared as the starting zeolite powder, and 100 g of this zeolite powder was mixed with 100 g of ion-exchanged water to prepare a slurry. The zeolite powder in this slurry was pulverized to an average particle size of 150 nm using a method similar to that for zeolite particles 1.

The slurry was then left to stand at 180°C for 2 to 3 hours to obtain finely pulverized zeolite powder. This zeolite powder was crushed in a mortar and passed through a mesh to adjust the particle size, obtaining zeolite particles 2.

(5) Dispersants Dispersant 1: Product name SOLSPERSE 41000, manufactured by Lubrizol Corporation, a surfactant containing a phosphate group.

2. Evaluation Tests The following evaluation tests were carried out on the Examples and Comparative Examples. The results are shown in the Table.

2.1 Viscosity The viscosity of the composition was measured using a rheometer (Model DHR-2, manufactured by Anton Paar Japan) at a temperature of 25° C. and a shear rate of 1000 s ⁻¹ .

2.2. Tackiness (curing property)
The composition was applied onto a smooth table, and then photocured by irradiating the composition with light for 15 seconds using an LED-UV irradiator manufactured by CCS Inc. under the conditions of a peak wavelength of 395 nm and an output of 100 mW/cm ^2. The atmosphere in which the light was irradiated was an oxygen-containing atmosphere (oxygen concentration 210 L/m ³ ) in Examples 1 to 14, 16 to 18, and Comparative Examples 1 and 2, and a nitrogen atmosphere (oxygen concentration 5 L/m ³ ) in Example 15. This resulted in a film having a thickness of 10 μm. The tester touched the surface of the film with his finger to judge whether or not it had tack. It was found that Examples 1 to 14 and 16 to 18 could achieve the same curability as Example 15, which was irradiated with light in a nitrogen atmosphere.
As a result, the tester rated the sample as "A" when the tester did not feel any tackiness, and as "C" when the tester felt a tackiness.

2.3. Transmittance A coating film was prepared by applying the composition, and this coating film was irradiated with light for 15 seconds using an LED-UV irradiator manufactured by CCS Inc. under conditions of a peak wavelength of 395 nm and approximately 100 mW/ ^cm2 to photocure the film, thereby preparing a film having a thickness of 10 μm. The atmosphere during light irradiation was the same as in 2.2 above. The total light transmittance of this film was measured according to JIS K7361-1.

2.4. Evaluation of outgassing of cured product When the cured product of the composition was heated, the outgassing was sampled by the headspace method and measured by gas chromatography. 100 mg of the composition was placed in a headspace vial, and the composition was irradiated with light at a peak wavelength of 395 nm and approximately 100 mW/ ^cm2 using an LED-UV irradiator manufactured by CCS Inc. to cure the composition, and then the vial was sealed and heated at 80°C for 30 minutes, after which the gas phase in the vial was introduced into a gas chromatograph for analysis. As a result, the case where the generated gas was 300 ppm or less was evaluated as "A", the case where the generated gas was more than 300 ppm but less than 500 ppm was evaluated as "B", and the case where the generated gas was 500 ppm or more was evaluated as "C".

2.5. Inkjet printability Using an inkjet printer, model MH2420 manufactured by Ricoh Co., Ltd., the composition was placed in the inkjet printer cartridge, and after confirming that the composition in the cartridge could be discharged from the nozzle of the inkjet printer, the composition was discharged from the nozzle to continuously print a test pattern. As a result, the composition was rated as "A" when it could be discharged for 1 hour and the discharge operation was stable, "B" when it could be discharged for 1 hour but the discharge operation became intermittently unstable, and "C" when the nozzle became clogged before 1 hour had passed since the start of discharge and it became impossible to discharge the composition.

2.6. Adhesion A silicon nitride film (refractive index 1.81) having a thickness of 100 nm was prepared on the surface of a quartz glass piece (dimensions 50 mm x 25 mm x 1 mm) by plasma CVD. A composition was applied onto the silicon nitride film to prepare a coating film having a thickness of 50 μm. This produced a first test piece.

A 100 nm thick silicon nitride film (refractive index 1.81) was produced on the surface of another piece of quartz glass (dimensions 76 mm x 52 mm x 1 mm) by plasma CVD. This produced a second test piece.

The silicon nitride film of the second test piece was placed on top of the coating film of the first test piece so that the area where the two contacted was 25 mm x 25 mm. The coating film was then cured by irradiating it with light for 15 seconds using an LED-UV irradiator manufactured by CCS Inc. under conditions of a peak wavelength of 395 nm and approximately 100 mW/ ^cm2 . The atmosphere during light irradiation was the same as in 2.2 above.

Next, the adhesion strength between the two quartz glass pieces was evaluated by conducting a tensile shear test (tensile speed 5 mm/min) in accordance with JIS-K-6850.

2.7 Storage stability The composition was left to stand for one month at 40°C under a nitrogen atmosphere. The viscosity of the composition before and after the test was measured using a rheometer (Anton Paar Japan, model DHR-2) at a temperature of 25°C and a shear rate of 1000 s ^-1 , and the rate of change in viscosity was calculated from the results. A rate of change of less than 5% was rated as "A", a rate of change of 5% or more but less than 10% was rated as "B", and a rate of change of 10% or more was rated as "C".

Claims (9)

A polythiol compound (A) having two or more thiol groups in one molecule;
An acrylic compound (B),
A photopolymerization initiator (C),
The viscosity of the polythiol compound (A) at 25° C. is 20 mPa ·s or more and 2000 mPa·s or less,
The acrylic compound (B) contains a monofunctional (meth)acrylic compound (B20),
The percentage of the monofunctional (meth)acrylic compound (B20) relative to the total amount of the acrylic compound (B) is more than 0 mass % and 70 mass% or less,
The content of the polythiol compound (A) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is 0.5% by mass or more and 10% by mass or less,
does not contain a radical polymerizable compound (G1) other than the acrylic compound (B), or contains the radical polymerizable compound (G1), and the amount of the radical polymerizable compound (G1) relative to the total amount of the acrylic compound (B) and the radical polymerizable compound (G1) is 10 mass% or less;
Contains no solvent or contains a solvent content of 1% by mass or less;
Formed by the inkjet method,
A composition for sealing a light-emitting element. The photopolymerization initiator (C) contains an aminoacetophenone compound (C1),
The content of the aminoacetophenone compound (C1) relative to the total amount of the polythiol compound (A) and the acrylic compound (B) is 1.0 mass% or more and 15 mass% or less.
The composition for sealing a light-emitting element according to claim 1 . The photopolymerization initiator (C) contains a sensitizer (D),
The sensitizer (D) includes a thioxanthone-based sensitizer (D1),
The content of the thioxanthone-based sensitizer (D1) relative to the photopolymerization initiator (C) is 1.0% by mass or more and 90% by mass or less.
The composition for sealing a light-emitting element according to claim 1 . The acrylic compound (B) includes a compound (B1) having an acryloyl group and a compound (B2) having a methacryloyl group,
a mass ratio of the compound (B1) to the compound (B2) is 1 or more and 74/25 or less;
The composition for sealing a light-emitting element according to claim 1 . Further containing a moisture absorbent (E),
The composition for sealing a light-emitting element according to claim 1 . The moisture absorbent (E) contains zeolite particles.
The composition for sealing a light-emitting element according to claim 5 . Contains no solvent or has a solvent content of 0.1% by mass or less;
The composition for sealing a light-emitting element according to claim 1 . A light emitting element and a sealing material that covers the light emitting element,
The encapsulant is a cured product of the composition for sealing a light-emitting element according to claim 1 .
Light emitting device. The light-emitting device according to claim 8 , which is a display device.

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