JP7847351B2 - UV-curable resin composition, light-emitting device, and method for manufacturing a light-emitting device - Google Patents

Description

This disclosure relates to an ultraviolet-curable resin composition, a light-emitting device, and a method for manufacturing a light-emitting device, and more specifically, to an ultraviolet-curable resin composition that can be applied by an inkjet method, a light-emitting device comprising a encapsulant made from a cured product of the ultraviolet-curable resin composition, and a method for manufacturing a light-emitting device using the ultraviolet-curable resin composition.

Organic EL (electroluminescent) light-emitting devices are being applied to lighting, displays, and other applications, and their widespread adoption is expected in the future.

In an organic EL light-emitting device, for example, organic EL elements are arranged on a support substrate, these organic EL elements are covered with an inorganic layer called a passivation layer, and the passivation layer is further covered with a encapsulating material made of organic resin.

It has been proposed to produce encapsulants for organic EL light-emitting devices using an inkjet method. For example, Patent Document 1 discloses the production of encapsulants by an inkjet method using an ink composition comprising 75 to 95 wt.% polyethylene glycol dimethacrylate monomer, 4 to 10 wt.% pentaerythritol tetraacrylate, and 1 to 15 wt.% of a spreading modifier having a viscosity in the range of about 14 to about 18 cps at 22°C and a surface tension in the range of about 35 to about 39 dynes/cm at 22°C.

Special table 2017-531049 publication

When a encapsulant is produced by applying the composition using an inkjet method, it is easier to produce the encapsulant with high positional accuracy and to reduce its thickness.

However, according to the inventor's own research, reducing the thickness of the encapsulant makes it easier for irregularities to form on the surface of the encapsulant due to the surface irregularities of the underlying inorganic material, making it difficult to smooth the surface of the encapsulant. This can easily lead to a decrease in the luminescence performance and durability of the organic EL light-emitting device.

Furthermore, to prevent moisture intrusion and thus prevent degradation of the organic EL elements, the encapsulant must be designed to minimize void formation. This requires high adhesion between the encapsulant and the underlying inorganic material, as well as minimal outgassing from the encapsulant.

The object of this disclosure is to provide an ultraviolet-curable resin composition that, when producing an encapsulant for sealing a light-emitting element by an inkjet method, is less likely to cause surface irregularities in the encapsulant, less likely to generate outgassing from the encapsulant, and can achieve high adhesion between the encapsulant and an inorganic material; a light-emitting device equipped with an encapsulant made from a cured product of this ultraviolet-curable resin composition; and a method for manufacturing a light-emitting device using this ultraviolet-curable resin composition.

An ultraviolet-curable resin composition according to one aspect of this disclosure,
A compound (A) consisting of at least one selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine;
Compound (B) represented by the following general formula (1),
CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3, R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in one molecule, each R is independently an alkylene group having 3 to 6 carbon atoms, and each X is independently a hydrogen atom or a methyl group.
A photopolymerization initiator (D) containing an acylphosphine oxide compound;
The viscosity at 25°C is 1 mPa·s or more and 40 mPa·s or less, and the viscosity at 40°C is 1 mPa·s or more and 40 mPa·s or less, satisfying at least one of these conditions.

A light-emitting device according to one aspect of the present disclosure comprises a light-emitting element and a sealing material for sealing the light-emitting element, wherein the sealing material includes a cured product of the ultraviolet-curable resin composition.

A method for manufacturing a light-emitting device according to one aspect of the present disclosure is a method for manufacturing a light-emitting device comprising a light-emitting element and a sealing material for sealing the light-emitting element, and includes producing the sealing material by applying the ultraviolet-curable resin composition by an inkjet method and then curing the ultraviolet-curable resin composition by irradiating it with ultraviolet light.

This is a schematic cross-sectional view of an organic EL light-emitting device in one embodiment of the present disclosure. This is a schematic perspective view of a semi-finished product of the same organic EL light-emitting device.

The following describes one embodiment of this disclosure. Note that the embodiment described below is only one of many embodiments of this disclosure. The following embodiment can be modified in various ways depending on the design, as long as the objectives of this disclosure are achieved.

The ultraviolet-curable resin composition according to this embodiment (hereinafter also referred to as composition (X)) is used to encapsulate light-emitting elements such as organic EL elements. Composition (X) contains compound (A), compound (B), and a photopolymerization initiator (D), and satisfies at least one of the following: a viscosity of 1 mPa·s or more and 40 mPa·s or less at 25°C, and a viscosity of 1 mPa·s or more and 40 mPa·s or less at 40°C. Due to the above configuration, composition (X) can be applied by inkjet method.

Compound (A) consists of at least one selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine.

Compound (B) is represented by the following formula.

CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3. R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in a molecule, each R is independently an alkylene group having 3 to 6 carbon atoms. X is independently a hydrogen atom or a methyl group.

The photopolymerization initiator (D) contains an acylphosphine oxide compound.

According to this embodiment, when a sealant is manufactured on an inorganic substrate, for example, when a sealant is manufactured by an inkjet method on a passivation layer made of an inorganic silicon compound, even if the substrate has irregularities, irregularities are less likely to form on the surface of the sealant, thereby improving the smoothness of the sealant. Furthermore, the sealant 5 can have high adhesion to the inorganic substrate and is less likely to generate outgassing from the sealant 5.

The above effects are presumed to have been achieved for the following reasons: Compound (A) can improve the adhesion between composition (X) and the inorganic material, making it easier for composition (X) to wet and spread on the inorganic material, thereby improving the smoothness of the sealant 5. Compound (B) is presumed to improve the adhesion between the sealant 5 and the inorganic material. Furthermore, the combination of compounds (A) and (B), along with the acylphosphine oxide compound, allows composition (X) to have good reactivity, which makes it difficult for unreacted substances to remain in the sealant 5, thus reducing outgassing. In addition, the combination of compounds (A) and (B) makes it easier to achieve viscosity and surface tension suitable for inkjet printing in composition (X). Moreover, since compounds (A) and (B) are relatively volatile, they do not impair the storage stability of composition (X).

Furthermore, the above mechanism is based on the inventor's speculation, and this embodiment is not bound by the aforementioned mechanism.

The cured product obtained by irradiating composition (X) with light and then heating it preferably has a glass transition temperature of 80°C or higher. In this case, the cured product can have good heat resistance. Therefore, for example, if the cured product is subjected to a treatment that involves a temperature increase, the cured product is less likely to deteriorate. The glass transition temperature of the cured product is more preferably 90°C or higher, and even more preferably 100°C or higher.

The viscosity of composition (X) at 25°C is preferably 1 mPa·s or more and 40 mPa·s or less. In this case, composition (X) can be applied and molded at room temperature by a casting method, an inkjet method, or the like. A viscosity of 35 mPa·s or less is more preferable, 30 mPa·s or less is even preferable, 20 mPa·s or less is particularly preferable, and 15 mPa·s or less is most preferable. A viscosity of 5 mPa·s or more is also preferable, and 8 mPa·s or more is more preferable. For example, a viscosity of 8 mPa·s or more and 35 mPa·s or less is preferable.

It is also preferable that the viscosity of composition (X) at 40°C is 1 mPa·s or more and 40 mPa·s or less. In this case, regardless of the viscosity of composition (X) at room temperature, it is possible to reduce the viscosity by slightly heating composition (X). Therefore, heating makes it easy to mold composition (X) by methods such as casting, and it is also possible to mold composition (X) by inkjet. Furthermore, since the viscosity can be reduced without significantly heating composition (X), it is possible to reduce the likelihood of changes in the composition of composition (X) due to the volatilization of components in composition (X). It is more preferable if this viscosity is 35 mPa·s or less, even more preferable if it is 30 mPa·s or less, particularly preferable if it is 20 mPa·s or less, and most preferable if it is 15 mPa·s or less. It is also preferable if this viscosity is 5 mPa·s or more, and more preferable if it is 8 mPa·s or more. For example, it is preferable if this viscosity is 8 mPa·s or more and 35 mPa·s or less.

The low viscosity of such composition (X) at 25°C or 40°C can be achieved by the composition of composition (X) as described in detail below.

When the thickness of the cured product of composition (X) is 10 μm, the total light transmittance is preferably 90% or more. In this case, when the cured product is applied to optical components such as the encapsulant 5 in the organic EL light-emitting device 1, the efficiency of extracting light that passes through the optical components 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.

It is also preferable that the surface tension of composition (X) is 20 mN/cm or more and 40 mN/cm or less. In this case, when composition (X) is applied by inkjet method, the ejection stability is good and it is less likely to produce defective droplets called satellites. It is more preferable if the surface tension is 25 mN/cm or more and 40 mN/cm or less, and even more preferable if it is 27 mN/cm or more and 38 mN/cm or less.

The embodiment will be described in more detail below.

1. Structure of an Organic EL Light-Emitting Device First, the structure of an organic EL light-emitting device 1, which is an example of a light-emitting device, will be explained. EL stands for electroluminescence. The organic EL light-emitting device 1 comprises an organic EL element 4, which is a light-emitting element, and a encapsulating material 5 that covers the organic EL element 4. The organic EL element 4 is also called an organic light-emitting diode. The encapsulating material 5 may cover the organic EL element 4 in direct contact with it, or it may cover the organic EL element 4 with some layer interposed between the encapsulating material 5 and the organic EL element 4. The organic EL light-emitting device 1 may be, for example, a lighting device or a display device (display).

The structure of the organic EL light-emitting device 1 will now be described. The organic EL light-emitting device 1 comprises an organic EL element 4 (organic light-emitting diode), a encapsulating material 5 covering the organic EL light-emitting element 4, and a passivation layer 6. The encapsulating material 5 and the passivation layer 6 overlap. EL stands for electroluminescence.

An example of the structure of the organic EL light-emitting device 1 will be described with reference to Figure 1. This organic EL light-emitting device 1 is a top-emission type. The organic EL light-emitting device 1 comprises a support substrate 2, a transparent substrate 3 facing the support substrate 2 at a distance, a partition wall 7 (black matrix) and an organic EL light-emitting element 4 located on the surface of the support substrate 2 facing the transparent substrate 3, and a passivation layer 6 and a sealing material 5 covering the organic EL light-emitting element 4.

The support substrate 2 is made from, for example, a resin material, but is not limited thereto. The transparent substrate 3 is made from a light-transmitting material. The transparent substrate 3 is, for example, a glass substrate or a transparent resin substrate. The light-emitting element 4 comprises, for example, a pair of electrodes 41 and 43 and an organic light-emitting layer 42 between the electrodes 41 and 43. The organic light-emitting layer 42 comprises, 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 order described above.

The partition walls 7 demarcate the surface of the support substrate 2. An organic EL element 4 is placed between two adjacent partition walls 7. The partition walls 7 are manufactured, for example, by molding a photosensitive resin material using a photolithography method. The partition walls 7 are arranged, for example, in a stripe pattern, that is, multiple partition walls 7 that are long in one direction are spaced apart in a direction perpendicular to their longitudinal direction. However, the arrangement of the partition walls 7 is not limited to the above, and for example, the partition walls 7 may be arranged in a grid pattern. The height of the partition walls 7 is, for example, 0.1 μm to 1.5 μm. The spacing between adjacent partition walls 7 is, for example, 30 μm to 150 μm.

The organic EL element 4 comprises, for example, a pair of electrodes 41 and 43 and an organic light-emitting layer 42 located between the electrodes 41 and 43. The organic light-emitting layer 42 comprises, 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 order described above. The organic EL light-emitting device 1 comprises a plurality of organic light-emitting elements 4, and the plurality of organic EL light-emitting elements 4 constitute an array 9 (hereinafter referred to as the element array 9) on the support substrate 2. The element array 9 also includes connecting wiring 8 that electrically connects the electrodes 43 and electron transport layers 424 of adjacent organic EL light-emitting elements 4. The connecting wiring 8 is provided so as to span across the partition wall 7.

The partition wall 7 protrudes from the organic EL element 4 on the side opposite to the support substrate 2, and the protrusion dimension of the partition wall 7 from the organic EL element 4 is, for example, 0.1 μm or more and 1.5 μm or less.

The passivation layer 6 is preferably made from 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 organic EL element 4 by covering the element array 9 while in direct contact with it. The first passivation layer 61 covers the surface of the organic EL element 4 and the top of the partition wall 7 that protrudes beyond the organic EL element 4. Therefore, the surface of the first passivation layer 61 has an uneven shape with protrusions corresponding to the position of the partition wall 7 (see Figure 2).

The second passivation layer 62 is positioned on the opposite side of the element array 9 from the first passivation layer 61, and there is a gap between the second passivation layer 62 and the first passivation layer 61.

A sealing material 5 is filled between the first passivation layer 61 and the second passivation layer 62. In other words, the first passivation layer 61 is interposed between the organic EL element 4 and the sealing material 5 covering the organic EL element 4.

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

The passivation layer 6 is preferably made from silicon nitride or silicon oxide, and is particularly preferably made from silicon nitride. In the example shown in Figure 1, the passivation layer 6 includes a first passivation layer 61 and a second passivation layer 62. The first passivation layer 61 covers the light-emitting element 4 by covering the element array 9 while in direct contact with the element array 9. The second passivation layer 62 is positioned on the opposite side of the element array 9 from the first passivation layer 61, and there is a gap between the second passivation layer 62 and the first passivation layer 61. The sealing material 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 sealing material 5 that covers the light-emitting element 4.

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

2. UV-curable resin composition The components of composition (X) will be described in detail. In this specification, "(meth)acrylate" means "acrylate or methacrylate," and "(meth)acryloyl group" means "acryloyl group or methacryloyl group." Furthermore, di(meth)acrylate means that the two (meth)acrylates may be the same or different.

Composition (X) contains a radical polymerizable compound, the radical polymerizable compound containing at least compound (A) and compound (B).

Compound (A) consists of at least one selected from the group comprising N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine, as described above.

Compound (A), by possessing nitrogen atoms, can enhance the affinity between the sealant 5 and the inorganic material. Therefore, when composition (X) is applied to an inorganic material substrate by inkjet printing, composition (X) is more likely to spread easily on the substrate, thereby improving the smoothness of the sealant 5.

Furthermore, compound (A) has low viscosity and low volatility. Therefore, compound (A) can reduce the viscosity of composition (X), making it suitable for application by inkjet printing, and can also improve the storage stability of composition (X). Additionally, it can reduce outgassing from the encapsulant 5. Moreover, because compound (A) has good reactivity, it can efficiently cure composition (X) to produce the encapsulant 5.

The proportion of compound (A) is preferably 20% by mass or more and 80% by mass or less of the total composition (X). When this proportion is 20% by mass or more, the smoothness of the sealant 5 tends to be particularly high. When this proportion is 80% by mass or less, the composition (X) and the sealant 5 are less likely to absorb excessive moisture, and therefore, the sealant 5 is less likely to peel off from the substrate due to expansion of the sealant 5 due to moisture. More preferably, this proportion is 25% by mass or more and 70% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

A preferred form of compound (A) contains at least N-acryloylmorpholine. The proportion of N-acryloylmorpholine is preferably 5% by mass or more and 60% by mass or less of the total composition (X). When this proportion is 5% by mass or more, the photocurability of the sealant 5 tends to be particularly high. When this proportion is 60% by mass or less, the composition (X) and the sealant 5 are less likely to absorb excessive moisture, and therefore, the sealant 5 is less likely to peel off from the substrate due to expansion of the sealant 5 due to moisture. This proportion is preferably 20% by mass or more and 55% by mass or less, more preferably 25% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

Compound (A) preferably contains N-acryloylmorpholine and at least one of N,N-dimethylacrylamide and N,N-diethylacrylamide. In this case, the smoothness of the sealant 5 tends to be higher. The total amount of N,N-dimethylacrylamide and N,N-diethylacrylamide is preferably 5% by mass or more and 20% by mass or less of the total amount of composition (X). When this percentage is 5% by mass or more, the smoothness of the sealant 5 tends to be particularly high. When this percentage is 20% by mass or less, composition (X) and the sealant 5 are less likely to absorb excessive moisture, and therefore the sealant 5 is less likely to peel off from the substrate due to expansion of the sealant 5 due to moisture. This percentage is more preferably 5% by mass or more and 18% by mass or less, and even more preferably 8% by mass or more and 15% by mass or less.

Composition (X) may further contain an N-substituted (meth)acrylamide (A-3) other than compound (A). The N-substituted (meth)acrylamide (A-3) can also increase the affinity between composition (X) and the inorganic material. The N-substituted (meth)acrylamide (A-3) includes, for example, at least one selected from the group consisting of N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-methyl-N-ethyl(meth)acrylamide, N-n-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide. The proportion of N-substituted (meth)acrylamide (A-3) in composition (X) is preferably 10% by mass or less.

Compound (B) is represented by the following general formula (1), as described above.

CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3. R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in one molecule, each R is independently an alkylene group having 3 to 6 carbon atoms. X is independently either an H or a methyl group.

Compound (B) is polar, which can increase the affinity between the sealant 5 and the inorganic material. Therefore, when composition (X) is applied to an inorganic material substrate by inkjet printing, composition (X) spreads more easily on the substrate, which is thought to improve the smoothness of the sealant 5. In addition, because R has three or more carbon atoms, the sealant 5 is less likely to absorb excessive moisture, which suppresses expansion of the sealant 5 due to moisture absorption. This also is thought to improve the smoothness of the sealant 5.

Furthermore, compound (B) has low viscosity and low volatility. Therefore, compound (B) can reduce the viscosity of composition (X), making it possible to apply it by inkjet method, and it can also improve the storage stability of composition (X), and further reduce outgassing from the sealant 5. In addition, because compound (B) has good reactivity, it can efficiently cure composition (X) to produce the sealant 5. Also, compound (B) can raise the glass transition temperature of the sealant 5. Therefore, the heat resistance of the sealant 5 can be improved.

Compound (B) preferably contains at least one selected from the group consisting of dipropylene glycol diacrylate, tripylene glycol diacrylate, neopentyl glycol diacrylate, and 3-methyl-1,5-pentanediol diacrylate. In this case, the above-mentioned effects of compound (B) are particularly easily obtained.

The proportion of compound (B) is preferably 5% by mass or more and 75% by mass or less of the total composition (X). A proportion of 5% by mass or more reduces outgassing from the sealant 5. A proportion of 75% by mass or less has the advantage of particularly increasing the smoothness of the sealant 5. More preferably, this proportion is 15% by mass or more and 65% by mass or less, and even more preferably 25% by mass or more and 60% by mass or less.

Composition (X) may further contain at least one of the following compounds other than compound (A), N-substituted (meth)acrylamide (A-3), and compound (B): a monofunctional (meth)acrylic compound (B2) and a difunctional (meth)acrylic compound (B3).

The monofunctional (meth)acrylate (B2) contains at least one selected from the group consisting of, for example, esters of alcohols having 2 to 30 carbon atoms and (meth)acrylic acid, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl acrylate, mono(meth)acrylate of o-, m-, or p-phenylphenol, mono(meth)acrylate of 3,3'-diphenyl-4,4'-dihydroxybiphenyl, and nonylphenoxypolyethylene glycol (meth)acrylate.

The difunctional (meth)acrylic compound (B3) contains at least one selected from the group consisting of, for example, an ester of a polyhydric (preferably 2-8 valent) alcohol having 2 to 30 carbon atoms and (meth)acrylic acid, an ester of an alkylene oxide (alkylene group with 2 to 4 carbon atoms) adduct of a polyhydric (preferably 2-8 valent) alcohol having 2 to 30 carbon atoms and (meth)acrylic acid (excluding compound (B)), an OH group-containing epoxy acrylate at both ends, a di(meth)acrylate of an ethylene oxide adduct of bisphenol A, and a di(meth)acrylate of an ethylene oxide adduct of fluorene.

The composition (X) preferably further contains a compound (C) having three or more (meth)acryloyl groups in one molecule. Compound (C) can increase the reactivity of composition (X) and can also increase the glass transition temperature of the encapsulant 5, thereby improving its heat resistance.

Compound (C) contains at least one selected from the group consisting of, for example, a trifunctional (meth)acryloyl compound having three (meth)acryloyl groups, a tetrafunctional (meth)acryloyl compound having four (meth)acryloyl groups, a pentafunctional (meth)acryloyl compound having five (meth)acryloyl groups, and a hexafunctional (meth)acryloyl compound having six (meth)acryloyl groups.

The trifunctional (meth)acryloyl compound contains at least one selected from the group consisting of, for example, esterified (meth)acrylic acid of a trivalent or higher (preferably 3 to 8 valent) alcohol having 3 to 30 carbon atoms [e.g., tri(meth)acrylate of glycerin, tri(meth)acrylate of trimethylolpropane, tri(meth)acrylate of pentaerythritol], and esterified (meth)acrylic acid of an alkylene oxide (alkylene group with 2 to 4 carbon atoms) adduct of a trivalent or higher (preferably 3 to 8 valent) alcohol having 3 to 30 carbon atoms [e.g., tri(meth)acrylate of an ethylene oxide adduct of trimethylolpropane].

The tetrafunctional (meth)acryloyl compound contains at least one selected from the group consisting of, for example, esterified (meth)acrylic acid of a tetravalent or higher (preferably tetravalent to octavalent) alcohol having 5 to 30 carbon atoms [e.g., tetra(meth)acrylate of pentaerythritol and tetra(meth)acrylate of dipentaerythritol]; and esterified (meth)acrylic acid of a 1 to 30 molar adduct of an alkylene oxide (alkylene group with 2 to 4 carbon atoms) of a tetravalent or higher (preferably octavalent) alcohol having 5 to 30 carbon atoms [e.g., tetra(meth)acrylate of an ethylene oxide adduct of pentaerythritol, tetra(meth)acrylate of an ethylene oxide adduct of dipentaerythritol].

The pentafunctional (meth)acryloyl compounds and hexafunctional (meth)acryloyl compounds contain at least one selected from the group consisting of, for example, esterified (meth)acrylic acid of a tetravalent or higher (preferably tetravalent to octavalent) alcohol having 5 to 30 carbon atoms [e.g., penta(meth)acrylate of dipentaerythritol and hexa(meth)acrylate of dipentaerythritol]; and esterified (meth)acrylic acid of a 1 to 30 molar adduct of an alkylene oxide (alkylene group with 2 to 4 carbon atoms) of a tetravalent or higher (preferably octavalent) alcohol having 5 to 30 carbon atoms [e.g., penta(meth)acrylate of the ethylene oxide adduct of dipentaerythritol, penta(meth)acrylate of the propylene oxide adduct of dipentaerythritol].

Compound (C) preferably contains at least one of a trifunctional (meth)acryloyl compound and a tetrafunctional (meth)acryloyl compound, and more preferably contains at least one selected from the group consisting of trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

The proportion of compound (C) is preferably more than 0% by mass and 10% by mass or less relative to the total composition (X). When this proportion is 10% by mass or less, the increase in viscosity of composition (X) is suppressed. More preferably, this proportion is 8% by mass or less, and even more preferably 5% by mass or less.

As described above, composition (X) contains a photopolymerization initiator (D), and the photopolymerization initiator (D) contains an acylphosphine oxide compound. Therefore, as described above, outgassing from the encapsulant 5 can be made less likely. The acylphosphine oxide compound contains at least one selected from the group consisting of, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

The photopolymerization initiator (D) may further contain compounds other than acylphosphine oxide compounds, for example, at least one selected from the group consisting of benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, α-aminoalkylphenone compounds, and oxime ester compounds. The benzoin compound may contain at least one selected from the group consisting of benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-hydroxycyclohexylphenyl ketone. The acetophenone compound contains, for example, at least one selected from the group consisting of acetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methylphenylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one. The anthraquinone compound contains, for example, at least one selected from the group consisting of 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-chloroanthraquinone, and 2-amylanthraquinone. The thioxanthone compound contains, for example, at least one selected from the group consisting of 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone. The ketal compound contains at least one selected from the group consisting of, for example, acetophenone dimethyl ketal and benzyl dimethyl ketal. The benzophenone compound contains at least one selected from the group consisting of, for example, benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide and 4,4'-bismethylaminobenzophenone. The α-aminoalkylphenone compound contains at least one selected from the group consisting of, for example, 2-methyl-1- [ 4- ( methylthio ) phenyl ] -2-morpholino -1- propanone and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone]. The oxime ester compound contains at least one selected from the group consisting of 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)] and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime), etc.

The proportion of the acylphosphine oxide compound is preferably 5% by mass or more and 20% by mass or less of the total composition (X). A proportion of 5% by mass or more particularly enhances the reactivity of composition (X) and suppresses outgassing from the sealant 5. A proportion of 20% by mass or less makes it easier to maintain a low viscosity of composition (X). More preferably, this proportion is 6% by mass or more and 19% by mass or less, and even more preferably 7% by mass or more and 18% by mass or less.

The composition (X) preferably contains a surfactant (E). In this case, the smoothness of the encapsulant 5 is further improved.

The surfactant (E) preferably contains at least one of a silicone-based surfactant and a fluorine-based surfactant. In this case, the composition (X) becomes more easily wettable and spreads on the inorganic material, which further enhances the smoothness of the sealant 5. In particular, when the surfactant (E) contains a silicone-based surfactant, the composition (X) becomes more easily wettable and spreads beyond the substrate and the protrusions. That is, for example, if the inorganic material substrate has striped protrusions as shown in Figure 2, when the composition (X) is applied to the substrate, the composition (X) becomes more easily wettable and spreads on the substrate in a direction perpendicular to the longitudinal direction of the protrusions. For this reason, the smoothness of the sealant 5 is particularly enhanced.

Furthermore, surfactant (E) may contain components other than silicone-based surfactants and fluorine-based surfactants.

The proportion of surfactant (E) is preferably 0.02% by mass or more and 1.0% by mass or less relative to the total composition (X). When this proportion is 0.02% by mass or more, the wettability of composition (X) to inorganic materials becomes particularly high, and the smoothness of the sealant 5 tends to be particularly high. Also, when this proportion is 1% by mass or less, the coating film produced by applying composition (X) to a substrate becomes less prone to foaming, and the smoothness of the sealant 5 tends to be high.

Composition (X) may contain various additives to exhibit various functionalities as needed. Specifically, the additive may contain at least one selected from the group consisting of light stabilizers, surface treatment agents, antioxidants, anti-aging agents, crosslinking accelerators, polymerization inhibitors, plasticizers, preservatives, pH adjusters, defoamers, and humectants. The total amount of additives is, for example, 1.0% by mass or less, 0.5% by mass or less, or 0.4% by mass or less, relative to the total amount of composition (X). This percentage is, for example, 0.05% by mass or more.

Composition (X) may further contain a desiccant (F). When composition (X) contains a desiccant (F), the cured product can have excellent hygroscopic properties. Preferably, the average particle size of the desiccant (F) is 200 nm or less. In this case, despite containing a desiccant (F), the cured product can have high transparency. Furthermore, when composition (X) is applied by inkjet printing, if the average particle size of the desiccant (F) is 200 nm or less, composition (X) is less likely to clog the nozzle. Moreover, if the average particle size of the desiccant (F) is 200 nm or less, the desiccant (F) is less likely to impair the smoothness of the surface of the sealant 5. Therefore, the surface of the sealant 5 can have good smoothness.

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

The average particle size of the desiccant (F) is preferably between 10 nm and 200 nm. If the average particle size is 200 nm or less, the sealing material 5 can have particularly high transparency. If the average particle size is 10 nm or more, the good hygroscopic properties of the desiccant (F) can be maintained. This average particle size is the median diameter, i.e., the cumulative 50% diameter (D50), calculated from the measurement results by dynamic light scattering. As the measuring device, the Nanotrac Wave series from Microtrac-Bell Co., Ltd. can be used.

The average particle size of the desiccant (F) is more preferably 150 nm or less, even more preferably 100 nm or less, and particularly preferably 70 nm or less. Furthermore, the average particle size of the desiccant (F) is preferably 20 nm or more, and more preferably 50 nm or more. In this case, the sealing material 5 can have particularly good transparency and hygroscopic properties.

It is also preferable that the cumulative 90% diameter (D90) of the hygroscopic agent (F) is 100 nm or less. In this case, the cured product can have particularly high transparency.

The proportion of the desiccant (F) to the total amount of composition (X) is preferably 1% by mass or more and 20% by mass or less. If the proportion of the desiccant (F) is 1% by mass or more, the cured product can have particularly high hygroscopicity. Also, if the proportion of the desiccant (F) is 20% by mass or less, the viscosity of composition (X) can be particularly reduced, and composition (X) can have a sufficiently low viscosity to be applied by inkjet method. The proportion of the desiccant (F) is more preferably 3% by mass or more, and particularly preferably 5% by mass or more. Also, the proportion of the desiccant (F) is more preferably 15% by mass or less, and particularly preferably 13% by mass or less.

Composition (X) may further contain inorganic fillers other than the hygroscopic agent (F). In particular, it is preferable that composition (X) contains nano-sized high refractive index particles. Examples of high refractive index particles include zirconia particles. When 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, the efficiency of light extraction that passes through the encapsulant 5 in the organic EL light-emitting device 1 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 to 30 nm, and more preferably in the range of 10 to 20 nm.

The proportion of high-refractive-index particles in composition (X) is appropriately designed so that the encapsulant 5 has a desired refractive index. In particular, it is preferable that the high-refractive-index particles are included in composition (X) such that the refractive index of the cured product is within the range of 1.45 or more and less than 1.55. In this case, the light extraction efficiency of the organic EL light-emitting device 1 is particularly improved.

If composition (X) contains a hygroscopic agent (F), it is preferable that composition (X) further contains a dispersant (G). In this case, the dispersant (G) can improve the dispersibility of the hygroscopic agent (F) in composition (X). Therefore, composition (X) is less likely to experience an increase in viscosity and a decrease in storage stability due to the hygroscopic agent (F).

The dispersant (G) is a surfactant that can adsorb to particles. The dispersant (G) has an adsorption group (generally also called an anchor) that can be adsorbed to particles, and a molecular skeleton (generally also called a tail) that adheres to the particles when the adsorption group is adsorbed to them. The dispersant (G) contains at least one component selected from the group consisting of, for example, an acrylic dispersant in which the tail is an acrylic molecular chain, a urethane dispersant in which the tail is a urethane molecular chain, and a polyester dispersant in which the tail is a polyester molecular chain. The adsorption group includes at least one of, for example, a basic polar functional group and an acidic polar functional group. The basic polar functional group includes at least one group selected from the group consisting of, for example, an amino group, an imino group, an amide group, an imide group, and a nitrogen-containing heterocyclic group. The acidic polar functional group includes at least one group selected from the group consisting of, for example, a carboxyl group and a phosphate group. The dispersant (G) may contain at least one compound selected from the group consisting of, for example, the Solspers series manufactured by Nippon Ruble Resol Co., Ltd., the DISPERBYK series manufactured by BIC Chemie Japan Co., Ltd., and the Azisper series manufactured by Ajinomoto Fine Techno Co., Ltd.

When composition (X) contains a hygroscopic agent (F), the amount of dispersant (G) per 100 parts by mass of hygroscopic agent (F) is preferably 5 parts by mass or more and 60 parts by mass or less. An amount of 5 parts by mass or more of dispersant (G) allows the function of the dispersant (G) to be effectively expressed, and an amount of 60 parts by mass or less suppresses the free molecules of dispersant (G) in the sealing material 5 from hindering the adhesion between the sealing material 5 and the inorganic material component. Furthermore, an amount of dispersant (G) of 15 parts by mass or more is more preferable, 50 parts by mass or less is even more preferable, 40 parts by mass or less is even more preferable, and 30 parts by mass or less is particularly preferable.

It is preferable that composition (X) does not contain a solvent, or that the solvent content is 1% by mass or less. In this case, it is not necessary to dry composition (X) to volatilize the solvent when preparing a cured product from composition (X). Furthermore, the storage stability of composition (X) is further improved. 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 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. It is preferable that composition (X) is liquid at 25°C.

The moisture content of composition (X) is preferably 100 ppm or less, more preferably 70 ppm or less, and particularly preferably 50 ppm or less, from the viewpoint of reducing outgassing.

3. Method for producing encapsulating material and method for producing organic EL light-emitting device A method for producing encapsulating material 5 using composition (X) and a method for producing organic EL light-emitting device 1 will be described.

In this embodiment, it is preferable to produce a coating film by forming the composition (X) using an inkjet method, then irradiate the coating film with ultraviolet light, and subsequently heat it to produce the sealing material 5. In this embodiment, it is possible to apply and form the composition (X) using an inkjet method.

When applying composition (X) by 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, and particularly 15 mPa·s or less, then composition (X) can be molded by applying it by inkjet method without heating.

If composition (X) has the property of becoming less viscous when heated, composition (X) may be heated and then coated and molded using an inkjet method. If the viscosity of composition (X) at 40°C is 30 mPa·s or less, particularly 15 mPa·s or less, the viscosity of composition (X) can be reduced by only slight heating, and this reduced-viscosity composition (X) can be ejected using an inkjet method. The heating temperature of composition (X) is, for example, 20°C to 50°C.

When curing a coating film obtained by molding composition (X) by irradiating it with light, the light irradiated onto the coating film is, for example, ultraviolet light. Ultraviolet light refers to light rays with a wavelength in the range of 200 nm to 410 nm. The wavelength of the light irradiated onto the coating film is preferably in the range of 350 nm to 410 nm, and more preferably 385 nm to 405 nm. One representative example of light irradiated onto the coating film is light with a wavelength of 395 nm. However, the wavelength of the light irradiated onto the coating film is not limited to the above description, as long as it can cure the coating film.

The irradiation intensity of the light applied to the coating film is preferably 20 mW/ ^m² or more and 20 W/ ^cm² or less. However, the irradiation intensity of the light is not limited to the above description as long as it can cure the coating film.

When irradiating a coating with light, the shape of the area illuminated by the light can be either an area type with a certain surface area or a line type. In the case of a line type, the entire coating can be irradiated with light by moving the coating relative to the light source, or by moving the light source relative to the coating. In this case, it is easy to adjust the time that the coating is irradiated with light, and by adjusting this time, it is easy to adjust the cumulative amount of light.

In this embodiment, the coating film may be cured by irradiating it with light in the atmosphere. In this embodiment, since composition (X) can have good reactivity, the reaction of composition (X) can proceed and be cured even in the atmosphere. It is particularly preferable to cure the coating film by irradiating it with light in a dry atmosphere. In this case, the absorption of moisture by composition (X) and the sealant 5 can be suppressed.

When further heating a cured coating, the heating temperature is preferably 90°C or higher. In this case, the curing of the coating is further advanced, making it easier to lower the coefficient of thermal expansion of the sealant 5.

More specifically, for example, first a support substrate 2 is prepared. A partition wall 7 (black matrix) is fabricated on one surface of this support substrate 2 using a photolithography method, for example, with a photosensitive resin material. Subsequently, a plurality of organic EL elements 4 are placed on one surface of the support substrate 2. The organic EL elements 4 can be fabricated by appropriate methods such as vapor deposition or coating. It is particularly preferable to fabricate the organic EL elements 4 using a coating method such as inkjet. This creates an element array 9 on the support substrate 2.

Next, a first passivation layer 61 is provided so as to cover the organic EL element 4 and the partition wall 7. The first passivation layer 61 can be fabricated by a deposition method such as plasma CVD. The surface of the first passivation layer 61 has an uneven shape with protrusions corresponding to the position of the partition wall 7, as shown in Figure 2 (see Figure 2).

Next, composition (X) is applied to the first passivation layer 61 by an inkjet method to create a coating film. Applying the inkjet method to both the formation of the organic EL element 4 and the application of composition (X) can particularly improve the manufacturing efficiency of the organic EL light-emitting device 1. Subsequently, the coating film is cured by irradiating it with ultraviolet light to create a encapsulant 5. In this embodiment, as described above, the surface of the encapsulant 5 is easily smoothed.

The thickness of the encapsulant 5 is, for example, 2 μm to 50 μm. It is also preferable that the thickness of the encapsulant 5 be 2 μm to 30 μm, and even more preferable that it be 2 μm to 15 μm. As described above, in this embodiment, it is easy to form small droplets of composition (X) at high density using the inkjet method, making it easy to realize a thin encapsulant 5 of 2 μm to 15 μm. By thinning the encapsulant 5 in this way, tensile and compressive stresses are less likely to occur in the encapsulant 5 within the organic EL light-emitting device 1. Therefore, it becomes easier to realize a flexible organic EL light-emitting device 1. In this embodiment, even when the encapsulant 5 is thinned, as described above, it is easy to smooth the surface of the encapsulant 5.

Next, a second passivation layer 62 is provided on top of the sealing material 5. The second passivation layer 62 can be fabricated by a vapor deposition method such as plasma CVD. In this embodiment, as described above, the sealing material 5 is easy to smooth, so defects caused by irregularities in the underlying sealing material 5 are less likely to occur in the second passivation layer 62.

Next, an ultraviolet-curable resin material is provided on 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, ultraviolet light is irradiated onto the transparent substrate 3 from the outside. The ultraviolet light passes through the transparent substrate 3 and reaches the ultraviolet-curable resin material. As a result, the ultraviolet-curable resin material hardens, and the second encapsulant 52 is produced.

The following are specific embodiments of this disclosure. However, this disclosure is not limited to the embodiments described below.

1. Preparation of Compositions The compositions of the Examples and Comparative Examples were prepared by mixing the components shown in the "Composition" column of the table below.

The details of the ingredients shown in the table are as follows:
-N,N-dimethylacrylamide: Trade name DMAA, manufactured by KJ Chemicals Co., Ltd.
-N-Acryloylmorpholine: Trade name ACMO, manufactured by KJ Chemicals Co., Ltd.
-N,N-diethylacrylamide: Trade name DEAA, manufactured by KJ Chemicals Co., Ltd.
-N-hydroxyethylacrylamide: Trade name HEAA, manufactured by KJ Chemicals Co., Ltd.
- Dipropylene glycol diacrylate: Trade name NK Ester APG100, manufactured by Shin Nakamura Chemical Industry Co., Ltd.
- Tripropylene glycol diacrylate: Trade name NK Ester APG-200, manufactured by Shin Nakamura Chemical Industry Co., Ltd.
- Neopentyl glycol diacrylate: Product name Light Acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.
-3-methyl-1,5-pentanediol diacrylate: trade name Light Acrylate MPD-A, manufactured by Kyoeisha Chemical Co., Ltd.
- Diethylene glycol diacrylate: Product name Funcryl FA-222A, manufactured by Hitachi Chemical Co., Ltd.
- Polyethylene glycol diacrylate: Product name NK Ester A-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.
- Polypropylene glycol diacrylate: Product name NK Ester APG-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.
- Pentaerythritol triacrylate: Product name Light Acrylate PE-3A, manufactured by Kyoeisha Chemical Co., Ltd.
- Dipentaerythritol hexaacrylate, trade name Neomer DA-600, manufactured by Sanyo Chemical Industries, Ltd.
-Bis(2,4,6-trimethylbenzoyl) -phenylphosphine oxide, trade name Omnirad819, manufactured by IGMResin.
- Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, trade name OmniradTPOH, manufactured by IGMResin.
-2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one: trade name Omnirad907, manufactured by IGMResin.
- Anthracure UVS-581: Manufactured by Kawasaki Chemical Industries, Ltd.
- Silicone-based surfactant 1: Product name TEGOTwin4000, manufactured by Evonik.
- Silicone-based surfactant 2: Product name TEGOTwin4200, manufactured by Evonik.
- Fluorine-based surfactant: Product name Surflon S-386, manufactured by AGC Seimi Chemical Co., Ltd.

2. Evaluation Tests The following evaluation tests were conducted on the examples and comparative examples. The results are shown in the table.

(1) Transmittance The composition was applied to a smooth surface, and then photocured in a dry atmosphere using an LED-UV irradiator manufactured by CCS Corporation under the conditions of a peak wavelength of 395 nm, an output of 1 W/ ^cm² , and an integrated light intensity of 1.5 J/ ^cm² . A film with a thickness of 15 μm was produced. The transmittance of this film at a wavelength of 430 nm was measured. A spectrophotometer (Hitachi, Ltd. U-4100) was used for the measurement.

(2) Viscosity The viscosity of the composition was measured using an E-type viscometer (TVE-35, manufactured by Toki Sangyo Co., Ltd.) under conditions of a rotation speed of 20 rpm and a temperature of 25°C.

(3) Surface Tension The surface tension of the composition was measured using the Wilhelmi method. For the measurement, a surface tension meter (Kyowa Interface Chemical Co., Ltd. Automatic Surface Tension Measuring Machine DY-300) was used, and the measurement was performed at a temperature of 25°C.

(4) Moisture content The moisture content of the composition was measured using a trace moisture analyzer (AQ-300 manufactured by Hiranuma Sangyo Co., Ltd.).

(5) Inkjet properties (initial)
The composition was placed in a cartridge of an inkjet printer (Ricoh, model MH2420), and after confirming that the composition could be ejected from the nozzles of the inkjet printer, the composition was ejected from the nozzles and test patterns were printed continuously. The ejection of the composition droplets from the nozzles was filmed with a high-speed camera to check whether the droplets separated and satellites were generated. The results were evaluated as follows: "A" if the droplets did not separate, "B" if the satellites separated from the original droplet and then integrated with the original droplet to become a single droplet again, and "C" if the satellites remained separated from the original droplet and did not integrate.

(6) Inkjet-resistant (after 24 hours)
The composition was subjected to a 24-hour storage process while circulating within an inkjet device. The circulation rate was 1 ml/min. Subsequently, the inkjet properties were evaluated using the same method as in the case of "(4) Inkjet properties (initial)" described above.

(7) Smoothness A pre-baked film was prepared by coating a glass substrate with a photosensitive polyimide resin (Toray Industries, product name Photoneece DL-1000) and heating it at 120°C for 3 minutes using a hot plate. The thickness of the pre-baked film was measured to be 2 μm using a Hitachi High Technology spectrophotometer (U-4100). This pre-baked film was exposed to light through a photomask, developed by immersing it in a developer solution (2.38% by mass solution of tetramethylammonium hydroxide) for 60 seconds, and then heated in a clean oven at 250°C for 60 minutes. This created a grid-like arrangement of partitions (black matrix) with a height of 0.5 μm on the glass substrate. The planar dimensions of the opening surrounded by the partitions were 70 μm × 250 μm.

A silicon nitride film with a thickness of 500 nm was formed on the entire surface of the glass substrate where the partition wall was formed, so as to cover the partition wall.

The composition was placed in a cartridge of an inkjet printer (Fujifilm MP2831 material printer). After confirming that the composition could be ejected from the nozzle of the inkjet printer, droplets of the composition were ejected from the nozzle at 600 dpi to produce a coating film with a maximum thickness of 5 μm.

Five minutes after preparing the coating film, the coating film was photocured in a dry atmosphere using an LED-UV irradiator manufactured by CCS Corporation under the conditions of a peak wavelength of 395 nm, an output of 100 mW/ ^cm² , and an integrated light intensity of 1500 mJ/ ^cm² to produce a sealant.

The coating film was observed 5 minutes after its preparation, immediately before irradiation with light. A flat surface of the coating film was evaluated as "A".

If the coating was not rated "A", the coating was left for 20 minutes without light irradiation after preparation, and then observed. If the surface of the coating was flat, it was rated "B", and if the surface was wavy, it was rated "C".

(8) Outgassing Evaluation When the cured composition was heated, the outgassing was sampled using the headspace method and measured by gas chromatography. Specifically, first, 100 mg of the composition was placed in a 22 mL headspace vial. Next, the composition was cured by irradiating it with light under atmospheric conditions using an LED-UV irradiator manufactured by CCS Corporation at a peak wavelength of 395 nm and approximately 100 mW/ ^cm² , and then the vial was sealed. Subsequently, the composition was heated at 80°C for 30 minutes, and the gas phase portion in the vial was introduced into a gas chromatograph and analyzed. As a result, the concentration of outgassing generated from the composition was determined based on the peak area of the obtained gas chromatogram. The outgassing concentration is the volume fraction of outgassing in the gas phase of the vial relative to the volume of the vial (22 mL).

The outgassing concentration was determined using toluene as the reference substance. Specifically, two reference samples with toluene concentrations of 1000 ppm and 100 ppm were prepared by volatilizing toluene in a vial. Each reference sample was introduced into a gas chromatograph and analyzed. From the peak areas of the two resulting chromatograms, the relationship between peak area and concentration was defined, and based on this result, the mass ratio of the outgassing concentrations was determined and evaluated according to the following criteria. In order for outgassing to be less likely to occur, this result is preferably 200 ppm or less, more preferably 100 ppm or less, even more preferably 70 ppm or less, and particularly preferably 50 ppm or less.
A: 50 ppm or less.
B: More than 50 ppm and 70 ppm or less.
C: More than 100 ppm.

(9) Adhesion A SiN film with a refractive index of 1.83 and a thickness of 0.5 μm was formed on the surface of a quartz glass piece (dimensions 50 mm × 25 mm × 1 mm) by plasma CVD. The composition was applied to the surface of the SiN film to create a coating with a thickness of 50 μm. Another quartz glass piece was placed on top of this coating so that the dimensions of the area where the two pieces were in contact were 12.5 mm × 25 mm. The composition was photocured in an atmospheric environment by irradiating it with ultraviolet light using an LED-UV irradiator manufactured by CCS Corporation under the conditions of a peak wavelength of 395 nm, an irradiation intensity of 5 W/ ^cm² , and an integrated light amount of 3000 mJ/ ^cm² .

Next, the adhesion strength between the two quartz glass pieces was measured by a tensile shear test (tensile speed 5 mm/min) in accordance with JIS K6850. The results were evaluated according to the following criteria.
A: 15N/ ^mm2 or more.
B: 5 N/ ^mm² or more and less than 15 N/ ^mm² .
C: Less than 5 N/ ^mm² .

The results in the table show that the compositions of Examples 1 to 27 have low initial viscosity and excellent inkjetability and smoothness. Furthermore, the cured products obtained by curing the compositions of Examples 1 to 27 do not generate outgassing easily and have excellent adhesion to inorganic materials. On the other hand, Comparative Example 1, which does not contain compound (A), has poor wettability with inorganic materials, poor smoothness, and poor adhesion. Similarly, the composition of Comparative Example 2, which contains only N-substituted (meth)acrylamide (A-3) other than compound (A), has poor smoothness and poor adhesion, just like Comparative Example 1. Comparative Example 2 also has high viscosity and poor inkjetability, making it unsuitable for inkjet methods. The composition of Comparative Example 3, which does not contain any bifunctional (meth)acrylic compound, is prone to outgassing from the encapsulant. Comparative Examples 4 to 6, which contain a bifunctional (meth)acrylic compound (B3) but do not contain compound (B), have poor adhesion to the encapsulant. Comparative Example 7, which does not contain an acylphosphine oxide initiator, is prone to outgassing from the encapsulant.

Claims (12)

A compound (A) consisting of at least one selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine;
Compound (B) represented by the following general formula (1),
CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3, R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in one molecule, each R is independently an alkylene group having 3 to 6 carbon atoms, and each X is independently a hydrogen atom or a methyl group.
A photopolymerization initiator (D) containing an acylphosphine oxide compound;
The viscosity at 25°C is 1 mPa·s or more and 40 mPa·s or less, and the viscosity at 40°C is 1 mPa·s or more and 40 mPa·s or less, satisfying at least one of these conditions.
For fabricating a sealing material to enclose a light-emitting element,
UV curable resin composition. The compound (B) contains at least one selected from the group consisting of dipropylene glycol diacrylate, tripylene glycol diacrylate, neopentyl glycol diacrylate, and 3-methyl-1,5-pentanediol diacrylate.
The ultraviolet-curable resin composition according to claim 1. The ultraviolet-curable resin composition according to claim 1 or 2, wherein the compound (A) comprises at least the N -acryloylmorpholin. The compound (A) comprises the N -acryloylmorpholine and at least one of the N,N-dimethylacrylamide and the N,N-diethylacrylamide.
The ultraviolet-curable resin composition according to claim 3. The total amount ratio of N,N-dimethylacrylamide and N,N-diethylacrylamide is 5% by mass or more and 20% by mass or less of the total amount of the UV-curable resin composition.
The ultraviolet-curable resin composition according to claim 4. The proportion of N-acryloylmorpholin is 5% by mass or more and 60% by mass or less of the total UV-curable resin composition.
The ultraviolet-curable resin composition according to any one of claims 3 to 5. The compound (C) further contains three or more (meth)acryloyl groups in one molecule.
The ultraviolet-curable resin composition according to any one of claims 1 to 6. It further contains surfactant (E),
The ultraviolet-curable resin composition according to any one of claims 1 to 7. The surfactant (E) contains at least one of a silicone-based surfactant and a fluorine-based surfactant.
The ultraviolet-curable resin composition according to claim 8. The moisture content of the UV -curable resin composition is 100 ppm or less.
The ultraviolet-curable resin composition according to any one of claims 1 to 9. The device comprises a light-emitting element and a sealing material that seals the light-emitting element, wherein the sealing material includes a cured product of an ultraviolet- curable resin composition .
The UV-curable resin composition is
A compound (A) consisting of at least one selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine;
Compound (B) represented by the following general formula (1),
CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3, R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in one molecule, each R is independently an alkylene group having 3 to 6 carbon atoms, and each X is independently a hydrogen atom or a methyl group.
A photopolymerization initiator (D) containing an acylphosphine oxide compound;
A light-emitting device that satisfies at least one of the following conditions: a viscosity of 1 mPa·s or more and 40 mPa·s or less at 25°C, and a viscosity of 1 mPa·s or more and 40 mPa·s or less at 40°C . A method for manufacturing a light-emitting device comprising a light-emitting element and a sealing material for sealing the light-emitting element,
The process includes applying an ultraviolet- curable resin composition by an inkjet method, and then curing the ultraviolet-curable resin composition by irradiating it with ultraviolet light to produce the sealing material.
The UV-curable resin composition is
A compound (A) consisting of at least one selected from the group consisting of N,N-dimethylacrylamide, N,N-diethylacrylamide, and N-acryloylmorpholine;
Compound (B) represented by the following general formula (1),
CH ₂ =CXCO-O-(R-O) _n -COCX=CH ₂ (1)
n is an integer between 1 and 3, R is an alkylene group having 3 to 6 carbon atoms, provided that if there are multiple R groups in one molecule, each R is independently an alkylene group having 3 to 6 carbon atoms, and each X is independently a hydrogen atom or a methyl group.
A photopolymerization initiator (D) containing an acylphosphine oxide compound;
The viscosity at 25°C is 1 mPa·s or more and 40 mPa·s or less, and the viscosity at 40°C is 1 mPa·s or more and 40 mPa·s or less, satisfying at least one of these conditions.
A method for manufacturing a light-emitting device.