JP7569983B2 - Ultraviolet-curable resin composition, optical component, method for manufacturing optical component, light-emitting device, and method for manufacturing light-emitting device - Google Patents

Description

The present invention relates to an ultraviolet-curable resin composition, an optical component, a method for manufacturing an optical component, a light-emitting device, and a method for manufacturing a light-emitting device. More specifically, the present invention relates to an ultraviolet-curable resin composition containing a cationic polymerizable compound and a photocationic polymerization initiator, an optical component containing a cured product of this ultraviolet-curable resin composition, a method for manufacturing this optical component, a light-emitting device including an encapsulant made of a cured product of this ultraviolet-curable resin composition, and a method for manufacturing this light-emitting device.

Light-emitting devices equipped with light-emitting elements such as organic EL elements and micro LEDs are used for lighting and display applications, and are expected to become more widespread in the future.

The light-emitting element in the light-emitting device is covered with a sealant to prevent the light-emitting element from deteriorating due to moisture. In this case, the light emitted by the light-emitting element passes through the sealant and is emitted to the outside. The sealant is made from a composition containing, for example, a cationic curable resin and a photocationic polymerization initiator (see Patent Document 1). In this case, the sealant can be made by curing the composition with ultraviolet light irradiation or the like, so that the sealant can be made without applying a thermal load to the light-emitting element.

Patent No. 5703429

The inventors have been conducting research and development into a technique for molding an ultraviolet-curable resin composition containing a cationic polymerizable compound by the inkjet method. In the process, the inventors have found a problem in that it is difficult to achieve a balance between the curability and storage stability of an ultraviolet-curable resin composition, particularly when the cationic polymerizable compound contains an epoxy compound. Specifically, when an ultraviolet-curable resin composition contains an epoxy compound, the curability is difficult to stabilize, and the molded product may not exhibit sufficient performance due to insufficient curing. In addition, if the amount of photocationic polymerization initiator is increased to stabilize the curability, the viscosity of the ultraviolet-curable resin composition increases over time, or even if the viscosity does not increase, the ultraviolet-curable resin composition becomes difficult to pass through a filter, which tends to deteriorate the moldability by the inkjet method.

The object of the present invention is to provide an ultraviolet-curable resin composition that is molded by an inkjet method, contains a cationic polymerizable compound including an epoxy compound, and is capable of enhancing curability while not impairing moldability by the inkjet method; an optical component that includes a cured product of this ultraviolet-curable resin composition; a method for manufacturing this optical component; a light-emitting device that includes an encapsulant made of a cured product of this ultraviolet-curable resin composition; and a method for manufacturing this light-emitting device.

The ultraviolet-curable resin composition according to one embodiment of the present invention contains a cationic polymerizable compound (A) and a photocationic polymerization initiator (B). The cationic polymerizable compound (A) contains an epoxy compound (A1). The total amount of potassium ions, calcium ions, sodium ions, magnesium ions, and ammonium ions in the epoxy compound (A1) is 20 mass ppm or less relative to the entire epoxy compound (A1). The ultraviolet-curable resin composition is molded by an inkjet method.

An optical component according to one aspect of the present invention includes a cured product of the ultraviolet-curable resin composition.

A method for producing an optical component according to one aspect of the present invention includes molding the ultraviolet-curable resin composition by an inkjet method, and then irradiating the ultraviolet-curable resin composition with ultraviolet light to cure it.

The light-emitting device according to one aspect of the present invention includes a light source and an optical component that transmits light emitted by the light source, and the optical component 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 invention is a method for manufacturing a light-emitting device including a light source and an optical component that transmits light emitted by the light source, and includes manufacturing the optical component by the method.

According to one aspect of the present invention, there are provided an ultraviolet-curable resin composition that contains a cationic polymerizable compound including an epoxy compound, has high curability, and is less likely to impair moldability by an inkjet method, an optical component that contains a cured product of this ultraviolet-curable resin composition, a method for manufacturing this optical component, a light-emitting device that includes an encapsulant made of a cured product of this ultraviolet-curable resin composition, and a method for manufacturing this light-emitting device.

1 is a schematic cross-sectional view showing a light-emitting device according to one embodiment of the present invention.

One embodiment of the present invention is described below.

The ultraviolet-curable resin composition according to this embodiment (hereinafter also referred to as composition (X)) contains a cationic polymerizable compound (A) and a photocationic polymerization initiator (B). The cationic polymerizable compound (A) contains an epoxy compound (A1). The total amount of potassium ions, calcium ions, sodium ions, magnesium ions, and ammonium ions in the epoxy compound (A1) is 20 mass ppm or less based on the total amount of the epoxy compound (A1). The composition (X) is molded by an inkjet method.

According to this embodiment, the curability of the composition (X) can be improved. This is presumably because, if the percentage of the total amount of impurity ions in the epoxy compound (A1) is 20 ppm by mass or less, the acid generated from the photocationic polymerization initiator (B) is less likely to be consumed by the impurity ions, and the photocationic polymerization reaction proceeds efficiently. Furthermore, even if the percentage of the total amount of impurity ions is thus 20 ppm by mass or less, the viscosity of the composition (X) does not easily increase over time, and the molecular weight does not easily increase, so that the moldability of the composition (X) by the inkjet method is not easily impaired.

When the curability of composition (X) is increased, the crosslink density of the cured product of composition (X) tends to increase, and therefore the properties of the cured product, such as hardness and barrier properties, tend to improve. In addition, when the curability of composition (X) is increased, the cured product tends to be less likely to discolor, and therefore the cured product tends to be less likely to yellow.

In addition, in this embodiment, the curability can be improved without increasing the amount of the photocationic polymerization initiator (B) in the composition (X). When the amount of the photocationic polymerization initiator is increased, the viscosity of the composition (X) is likely to increase. In addition, when the amount of the photocationic polymerization initiator is increased, the storage stability of the composition (X) is likely to decrease. That is, the reaction of the cationic polymerizable compound (F) in the composition (X) gradually progresses during storage, causing the viscosity of the composition (X) to increase over time, which makes it more likely to cause molding defects when molding by the inkjet method. Even if the viscosity does not increase, when the composition (X) is circulated in the inkjet device, the polymerized components tend to clog the filter. This deteriorates the moldability by the inkjet method. However, in this embodiment, the curability can be improved without increasing the amount of the photocationic polymerization initiator, so that the moldability by the inkjet method is less likely to deteriorate.

In addition, in this embodiment, by reducing the amount of photocationic polymerization initiator (B), the viscosity of composition (X) can be reduced and the increase in viscosity of composition (X) over time can be suppressed, so there is no need to set the viscosity of composition (X) to a value that takes into account the increase in viscosity, etc. This allows for a wider range of choices for components such as the epoxy compound (A1) in the cationically polymerizable compound (A).

It is preferable that the outgassing rate generated when the cured product of composition (X) is heated at 100°C for 30 minutes is 100 ppm or less. In this case, outgassing is unlikely to occur from the cured product. Therefore, it is possible to make it difficult for gaps due to outgassing to occur in a light-emitting device equipped with an optical component containing the cured product, for example. This makes it difficult for water and oxygen to reach the light-emitting element through the gap, making it difficult for the light-emitting element to deteriorate due to water and oxygen. It is more preferable that the outgassing rate is 100 ppm or less, and even more preferable that it is 50 ppm or less. The method and conditions for measuring the outgassing rate will be explained in detail in the Examples section below.

It is preferable that the composition (X) does not contain a solvent, or the content of the solvent (percentage of the solvent to the entire composition (X)) is 1 mass% or less. In this case, outgassing due to the solvent is unlikely to occur from the composition (X) and the cured product of the composition (X). Therefore, the viscosity change of the composition (X) due to the evaporation of the solvent is unlikely to occur, and the storage stability of the composition (X) is improved. In addition, it is possible to make it difficult for voids due to outgassing to occur in the cured product. Therefore, it is possible to make it difficult for water to penetrate into the light-emitting device through the voids. In addition, it is possible to eliminate the need for a drying process for removing the solvent from the composition (X) and the cured product when producing the cured product. There may be a drying process for removing the solvent from at least one of the composition (X) and the cured product, but in this case, it is possible to reduce at least one of the heating temperature and the heating time in the drying process. Therefore, it is possible to make it difficult for outgassing to occur from the cured product without reducing the production efficiency of the cured product. Furthermore, if the composition (X) does not contain a solvent or the content of the solvent is 1% by mass or less, when the composition (X) is molded, particularly by the inkjet method, the thickness of the composition (X) after molding is unlikely to decrease due to the evaporation of the solvent, and therefore the thickness of the cured product is unlikely to decrease. Therefore, while molding by the inkjet method, the thickness of the cured product can be ensured to be as large as possible, and the wavelength conversion ability of the cured product can be ensured to be as large as possible. The content of the solvent 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. The content of the solvent in the composition (X) may be more than 1% by mass.

The glass transition temperature of the cured product of composition (X) is preferably 100°C or higher. That is, composition (X) preferably has the property of becoming a cured product with a glass transition temperature of 100°C or higher when cured. In this case, the cured product can have good heat resistance. Therefore, for example, when the cured product is subjected to a treatment accompanied by a temperature increase, the cured product is less likely to deteriorate. Therefore, for example, when a protective layer is produced by a deposition method such as a plasma CVD method to cover a molded product such as an optical part produced from composition (X), the molded product is less likely to deteriorate even if the molded product is heated. In addition, by increasing the heat resistance, the molded product can be adapted to an in-vehicle application that has strict requirements for heat resistance. It is more preferable that the glass transition temperature of the cured product is 120°C or higher. This glass transition temperature of the cured product can be achieved by the composition of composition (X) described in detail below. An example of a method for measuring the glass transition temperature will be described in detail in the Examples section below.

At least one of the viscosities of composition (X) at 25°C and 40°C is preferably 20 mPa·s or less. Examples of methods for measuring the viscosity are described in detail in the Examples section below.

If the viscosity of composition (X) at 25°C is 20 mPa·s or less, composition (X) can be easily molded by the inkjet method at room temperature. It is more preferable that this viscosity is 15 mPa·s or less. It is also preferable that this viscosity is 1 mPa·s or more, and it is also preferable that this viscosity is 5 mPa·s or more.

When the viscosity of composition (X) at 40°C is 20 mPa·s or less, it is possible to reduce the viscosity of composition (X) by slightly heating it, regardless of the viscosity of composition (X) at room temperature. Therefore, by heating, composition (X) can be easily molded by the inkjet method. In addition, since the viscosity of composition (X) can be reduced without significantly heating it, it is possible to reduce the change in the composition of composition (X) due to the volatilization of the components in composition (X). It is more preferable that this viscosity is 15 mPa·s or less. It is also preferable that this viscosity is 1 mPa·s or more, and it is also preferable that this viscosity is 5 mPa·s or more.

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

The volatility of 20 mg of composition (X) when heated at 100°C for 30 minutes using a thermogravimetric analyzer is preferably 40% or less. The volatility of composition (X) is defined as the percentage of the weight loss of composition (X) after treatment (the difference between the weight of composition (X) before treatment and the weight of composition (X) after treatment) relative to the weight of composition (X) before treatment. In this case, the low volatility of composition (X) can improve the storage stability of composition (X). In addition, outgassing is less likely to occur from the cured product. Therefore, voids due to outgassing are even less likely to occur in the cured product. The volatility of composition (X) can be determined by heating 20 mg of composition (X) at 100°C for 30 minutes using a thermogravimetric analyzer and calculating the weight loss of the weight after treatment relative to the weight before treatment. The volatility of 20 mg of composition (X) when heated at 100°C for 30 minutes using a thermogravimetric analyzer is more preferably 30% or less, and even more preferably 20% or less. The lower limit of the volatility of composition (X) is not particularly limited, but may be, for example, 0.1% or more.

When the cured product of composition (X) has a thickness dimension of 10 μm, the transmittance of light with a wavelength of 430 nm is preferably 95% or more. In this case, when the cured product is applied to an optical component such as the encapsulant 5 in the light-emitting device 1, the extraction efficiency of light that passes through the optical component 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) described in detail below. Details of the method for measuring the transmittance of the cured product will be described in detail in the examples below. Note that, depending on the application of composition (X), the cured product may not achieve the above transmittance.

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 discharged by an inkjet method, the discharge stability is good, and defective droplets called satellites are less likely to be generated. It is more preferable that the surface tension is 30 mN/cm or more and 40 mN/cm or less, and even more preferable that the surface tension is 31 mN/cm or more and 38 mN/cm or less.

This embodiment will be explained in more detail below.

The cationically polymerizable compound (A) is a compound having a cationically polymerizable functional group. The cationically polymerizable functional group is, for example, at least one group selected from the group consisting of an epoxy group, an oxetane group, and a vinyl ether group. In this embodiment, the cationically polymerizable compound (A) contains at least a compound having an epoxy group, i.e., an epoxy compound (A1).

As described above, the percentage of the total amount of potassium ions, calcium ions, sodium ions, magnesium ions and ammonium ions in the epoxy compound (A1) is 20 mass ppm or less based on the entire epoxy compound (A1). The potassium ions, calcium ions, sodium ions, magnesium ions and ammonium ions are impurities mixed in the epoxy compound (A1). Hereinafter, the potassium ions, calcium ions, sodium ions, magnesium ions and ammonium ions are also referred to as impurity ions. It is more preferable that the percentage of the total amount of impurity ions is 15 mass ppm or less, and even more preferable that it is 10 mass ppm or less. It is particularly preferable that the epoxy compound (A1) does not contain any impurity ions.

When the percentage of the total amount of impurity ions in the epoxy compound (A1) exceeds 20 mass%, it is preferable to subject the epoxy compound (A1) to a treatment to reduce the amount of impurity ions. For example, the amount of impurity ions in the epoxy compound (A1) can be reduced by washing the epoxy compound (A1) with water. Note that a treatment other than washing with water may be used to reduce the amount of impurity ions.

The epoxy compound (A1) can contain at least one of a monofunctional epoxy compound (A11) and a polyfunctional epoxy compound (A12).

The cationic polymerizable compound (A) may contain a compound other than the epoxy compound (A1). In particular, it is preferable that the cationic polymerizable compound (A) contains a compound having an oxetane group, i.e., the oxetane compound (A2). In this case, when the composition (X) is irradiated with ultraviolet light, the initial reactivity is increased by the epoxy compound (A1) and the final reactivity is increased by the oxetane compound (A2), so that the reactivity of the composition (X) is likely to be improved overall. When the cationic polymerizable compound (A) contains the oxetane compound (A2), the mass ratio of the epoxy compound (A1) to the oxetane compound (A2) is preferably from 20:80 to 60:40, more preferably from 25:75 to 55:45, and even more preferably from 30:70 to 50:50.

The oxetane compound (A2) can contain at least one of a monofunctional oxetane compound (A21) and a polyfunctional oxetane compound (A22).

The cationically polymerizable compound (A) may contain a compound having a vinyl ether group, i.e., a vinyl ether compound (A3). However, since the vinyl ether compound (A3) tends to have a low boiling point and also tends to lower the glass transition temperature of the cured product, it is preferable that the cationically polymerizable compound (A) does not contain the vinyl ether compound (A3), and if it does contain it, the percentage of the vinyl ether compound (A3) relative to the cationically polymerizable compound (A) is preferably 5 mass% or less.

The cationic polymerizable compound (A) will now be described in more detail.

The cationic polymerizable compound (A) contains, for example, at least one of a polyfunctional cationic polymerizable compound (W1) and a monofunctional cationic polymerizable compound (W2).

The polyfunctional cationic polymerizable compound (W1) can contain either or both of a polyfunctional cationic polymerizable compound (W11) that does not have a siloxane skeleton and a polyfunctional cationic polymerizable compound (W12) that has a siloxane skeleton.

The polyfunctional cationic polymerizable compound (W11) does not have a siloxane skeleton and has two or more cationic polymerizable functional groups per molecule. The number of cationic polymerizable functional groups per molecule of the polyfunctional cationic polymerizable compound (W11) is preferably 2 to 4, and more preferably 2 to 3.

The polyfunctional cationic polymerizable compound (W11) contains at least one compound selected from the group consisting of, for example, polyfunctional alicyclic epoxy compounds (A121), polyfunctional heterocyclic epoxy compounds (A122), polyfunctional oxetane compounds (A221), alkylene glycol diglycidyl ethers (A123), and alkylene glycol monovinyl monoglycidyl ethers. The polyfunctional epoxy compound (A12) may contain at least one compound selected from the group consisting of polyfunctional alicyclic epoxy compounds (A121), polyfunctional heterocyclic epoxy compounds (A122), and alkylene glycol diglycidyl ethers (A123). The polyfunctional oxetane compound (A22) may contain a polyfunctional oxetane compound (A221). The alkylene glycol monovinyl monoglycidyl ether is a compound contained in the monofunctional epoxy compound (A11) and is also a compound contained in the vinyl ether compound (A3).

The polyfunctional alicyclic epoxy compound (A121) contains, for example, one or both of the compound shown in the following formula (1) and the compound shown in the following formula (20).

In formula (1), each of R ¹ to R ¹⁸ is independently a hydrogen atom, a halogen atom, or a hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably within the range of 1 to 20. The hydrocarbon group is, for example, an alkyl group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, or a propyl group; an alkenyl group having 2 to 20 carbon atoms, such as a vinyl group or an allyl group; or an alkylidene group having 2 to 20 carbon atoms, such as an ethylidene group or a propylidene group. The hydrocarbon group may contain an oxygen atom or a halogen atom. Each of R ¹ to R ¹⁸ is independently preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

In formula (1), X is a single bond or a divalent organic group, and the organic group is, for example, -CO-O-CH2-.

Examples of the compound represented by formula (1) include the compound represented by formula (1a) below and the compound represented by formula (1b) below.

In formula (20), each of R ¹ to R ¹² is independently a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms. The halogen atom is, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. The hydrocarbon group having 1 to 20 carbon atoms is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group; an alkenyl group having 2 to 20 carbon atoms such as a vinyl group or an allyl group; or an alkylidene group having 2 to 20 carbon atoms such as an ethylidene group or a propylidene group. The hydrocarbon group having 1 to 20 carbon atoms may contain an oxygen atom or a halogen atom.

Each of R ¹ to R ¹² independently is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a methyl group, and most preferably a hydrogen atom.

An example of the compound represented by formula (20) includes the tetrahydroindene diepoxide represented by the following formula (20a):

The polyfunctional heterocyclic epoxy compound (A122) contains, for example, a trifunctional epoxy compound as shown in the following formula (2).

The polyfunctional oxetane compound (A221) contains, for example, a bifunctional oxetane compound as shown in the following formula (3).

The alkylene glycol diglycidyl ether (A123) contains at least one compound selected from the group consisting of compounds represented by the following formulas (4) to (7).

The alkylene glycol monovinyl monoglycidyl ether contains, for example, the compound shown in formula (8) below.

More specifically, the polyfunctional cationic polymerizable compound (W11) can contain at least one component selected from the group consisting of, for example, CELLOXIDE 2021P and CELLOXIDE 8010 manufactured by Daicel, TEPIC-VL manufactured by Nissan Chemical, OXT-221 manufactured by Toagosei, and 1,3-PD-DEP, 1,4-BG-DEP, 1,6-HD-DEP, NPG-DEP, and butylene glycol monovinyl monoglycidyl ether manufactured by Yokkaichi Chemical.

It is also preferable that the polyfunctional cationically polymerizable compound (W11) contains a polyfunctional alicyclic epoxy compound (A121). In this case, the composition (X) can have particularly high cationic polymerization reactivity.

It is particularly preferable that the polyfunctional alicyclic epoxy compound (A121) contains either or both of the compound shown in formula (1) and the compound shown in formula (20). In this case, the composition (X) can have higher cationic polymerization reactivity.

When the polyfunctional alicyclic epoxy compound (A121) contains a compound represented by formula (1), the compound represented by formula (1) preferably contains a compound represented by formula (1a). In this case, the composition (X) can have a higher cationic polymerization reactivity and a particularly low viscosity.

In addition, since the compound shown in formula (20) has a low viscosity, when the compound shown in formula (20) is contained, the composition (X) can have good ultraviolet curing properties and a particularly low viscosity. Furthermore, the compound shown in formula (20) has a low viscosity but is difficult to volatilize. Therefore, even if the composition (X) contains the compound shown in formula (20), the composition (X) is unlikely to undergo a change in composition due to the volatilization of the compound shown in formula (20). Therefore, by containing the compound shown in formula (20), the viscosity of the composition (X) can be reduced without impairing storage stability.

The compound shown in formula (20) can be synthesized, for example, by oxidizing a cyclic olefin compound having a tetrahydroindene skeleton using an oxidizing agent.

The compound shown in formula (20) may contain four stereoisomers based on the stereoconfiguration of the two epoxy rings. The compound shown in formula (20) may contain any of the four stereoisomers. That is, the compound shown in formula (20) may contain at least one component selected from the group consisting of the four stereoisomers. In the compound shown in formula (20), the total percentage of the exo-endo isomer and the endo-endo isomer among the four stereoisomers is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total epoxy compound (A1). In this case, the heat resistance of the cured product can be improved. The percentage of a specific stereoisomer in the compound shown in formula (20) can be determined based on the peak area ratio appearing in a chromatogram obtained by gas chromatography.

In order to reduce the amount of exo-endo and endo-endo isomers in the compound represented by formula (20), appropriate methods can be applied, such as a method of subjecting the compound represented by formula (20) to precision distillation or a method of applying column chromatography using silica gel or the like as a packing material.

When the composition (X) contains a polyfunctional cationic polymerizable compound (W11), the percentage of the polyfunctional cationic polymerizable compound (W11) relative to the total amount of the resin components is preferably 5% by mass or more and 95% by mass or less. The resin components refer to compounds having cationic polymerizability in the composition (X), and include the polyfunctional cationic polymerizable compound (W1) and the monofunctional cationic polymerizable compound (W2). If the percentage of the polyfunctional cationic polymerizable compound (W11) is 5% by mass or more, the composition (X) can have particularly excellent reactivity during the photocationic polymerization reaction, and the cured product can have high strength (hardness). In addition, if the percentage of the polyfunctional cationic polymerizable compound (W11) is 95% by mass or less, when the composition (X) contains a moisture absorbent (E), the moisture absorbent (E) can be particularly easily dispersed uniformly in the composition (X). The percentage of this polyfunctional cationic polymerizable compound (W11) is more preferably 12% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. The percentage of this polyfunctional cationic polymerizable compound (W11) is more preferably 85% by mass or less, and even more preferably 60% by mass or less. For example, the percentage of the polyfunctional cationic polymerizable compound (W11) is preferably 20% by mass or more and 60% by mass or less.

When the polyfunctional cationic polymerizable compound (W11) contains a polyfunctional alicyclic epoxy compound (A121), the polyfunctional alicyclic epoxy compound (A121) may be a part or the whole of the polyfunctional cationic polymerizable compound (W11). The percentage of the polyfunctional alicyclic epoxy compound (A121) relative to the polyfunctional cationic polymerizable compound (W11) is preferably 15% by mass to 100% by mass or less. When this percentage is 15% by mass or more, the polyfunctional alicyclic epoxy compound (A121) can particularly contribute to improving the ultraviolet curing property of the composition (X).

The polyfunctional cationic polymerizable compound (W12) has a siloxane skeleton and two or more cationic polymerizable functional groups per molecule. The number of cationic polymerizable functional groups per molecule of the polyfunctional cationic polymerizable compound (W12) is preferably 2 to 6, more preferably 2 to 4. The polyfunctional cationic polymerizable compound (W12) can contribute to improving the cationic polymerization reactivity of the composition (X) and can also contribute to improving the heat discoloration resistance of the cured product and optical components. The polyfunctional cationic polymerizable compound (W12) can also contribute to lowering the elastic modulus of the cured product and optical components. When the composition (X) contains a moisture absorbent, the polyfunctional cationic polymerizable compound (W12) can also contribute to improving the dispersibility of the moisture absorbent in the composition (X) and the cured product.

It is preferable that the polyfunctional cationic polymerizable compound (W12) is liquid at 25°C. In particular, it is preferable that the viscosity of the polyfunctional cationic polymerizable compound (W12) at 25°C is in the range of 10 to 300 mPa·s. In this case, the increase in viscosity of the composition (X) can be suppressed.

The cationically polymerizable functional group possessed by the multifunctional cationically polymerizable compound (W12) is, for example, at least one group selected from the group consisting of an epoxy group, an oxetane group, and a vinyl ether group.

The siloxane skeleton of the polyfunctional cationically polymerizable compound (W12) may be linear, branched, or cyclic. The number of Si atoms in the siloxane skeleton is preferably within the range of 2 to 14. In this case, the composition (X) can have a particularly low viscosity. The number of Si atoms is more preferably within the range of 2 to 10, even more preferably within the range of 2 to 7, and particularly preferably within the range of 3 to 6.

The polyfunctional cationically polymerizable compound (W12) can contain a polyfunctional epoxy compound (A221) having multiple epoxy groups in one molecule. The polyfunctional epoxy compound (A221) is included in the above-mentioned polyfunctional epoxy compound (A22).

The polyfunctional epoxy compound (A221) contains, for example, at least one of the compound shown in formula (10) and the compound shown in formula (11).

In each of formulas (10) and (11), R is a single bond or a divalent organic group, and is preferably an alkylene group. Y is a siloxane skeleton, which may be linear, branched, or cyclic, and the number of Si atoms is preferably within the range of 2 to 14, more preferably within the range of 2 to 10, even more preferably within the range of 2 to 7, and particularly preferably within the range of 3 to 6. n is an integer of 2 or more, and is preferably within the range of 2 to 4.

More specifically, for example, the polyfunctional epoxy compound (A221) contains a compound shown in the following formula (10a):

In formula (10a), R is a single bond or a divalent organic group, and is preferably an alkylene group having 1 to 4 carbon atoms. In formula (10a), n is an integer of 0 or more. n is preferably in the range of 0 to 12, more preferably in the range of 0 to 8, even more preferably in the range of 0 to 5, and particularly preferably in the range of 1 to 4.

The compound represented by formula (10a) preferably contains a compound represented by the following formula (30). In other words, the polyfunctional epoxy compound (A221) preferably contains a compound represented by the following formula (30).

More specifically, the polyfunctional epoxy compound (A221) preferably contains at least one component selected from the group consisting of product numbers X-40-2669, X-40-2670, X-40-2715, X-40-2732, X-22-169AS, X-22-169B, X-22-2046, X-22-343, X-22-163, and X-22-163B manufactured by Shin-Etsu Chemical Co., Ltd.

The polyfunctional epoxy compound (A221) preferably has an alicyclic epoxy structure, and it is particularly preferred if the polyfunctional epoxy compound (A221) contains a compound represented by formula (10a). The compound represented by formula (10a) can particularly contribute to improving the cationic polymerization reactivity and reducing the viscosity of the composition (X), and can also particularly contribute to improving the heat discoloration resistance and reducing the elastic modulus of the cured product and optical components. When the composition (X) contains a moisture absorbent (E), it can also particularly contribute to improving the dispersibility of the moisture absorbent (E) in the composition (X).

When the composition (X) contains a polyfunctional cationic polymerizable compound (W12), the percentage of the polyfunctional cationic polymerizable compound (W12) relative to the total amount of the resin components is preferably 5% by mass or more and 95% by mass or less. In this case, when the composition (X) contains a moisture absorbent (E), the dispersibility of the moisture absorbent (E) in the composition (X) and in the cured product is particularly improved, and the composition (X) can have a particularly high photocationic polymerization reactivity.

The monofunctional cationically polymerizable compound (W2) has only one cationically polymerizable functional group per molecule. The cationically polymerizable functional group is, for example, at least one group selected from the group consisting of an epoxy group, an oxetane group, and a vinyl ether group.

The viscosity of the monofunctional cationic polymerizable compound (W2) at 25°C is preferably 8 mPa·s or less. In this case, even if the composition (X) does not contain a solvent, the monofunctional cationic polymerizable compound (W2) can reduce the viscosity of the composition (X). In particular, the viscosity of the monofunctional cationic polymerizable compound (W2) at 25°C is preferably within the range of 0.1 to 8 mPa·s.

The monofunctional cationic polymerizable compound (W2) can contain at least one compound selected from the group consisting of the compounds shown in the following formulas (12) to (17) and limonene oxide. That is, the above monofunctional epoxy compound (A11) can contain at least one compound selected from the group consisting of the compound shown in the following formula (13), the compound shown in the following formula (14), the compound shown in the following formula (15), and limonene oxide. The above monofunctional oxetane compound (A21) can contain at least one of the compound shown in the following formula (12) and the compound shown in the following formula (17).

The percentage of the monofunctional cationic polymerizable compound (W2) relative to the total amount of the resin components is preferably 5% by mass or more and 50% by mass or less. If the percentage of the monofunctional cationic polymerizable compound (W2) is 5% by mass or more, the viscosity of the composition (X) can be particularly reduced. Furthermore, if the percentage of the monofunctional cationic polymerizable compound (W2) is 50% by mass or less, the composition (X) can have particularly excellent reactivity during the photocationic polymerization reaction, and the cured product can have high strength (hardness). The percentage of this monofunctional cationic polymerizable compound (W2) is more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the percentage of this monofunctional cationic polymerizable compound (W2) is more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. If the percentage of the monofunctional cationic polymerizable compound (W2) is particularly 35% by mass or less, the amount of volatilization of the components in the composition (X) during storage of the composition (X) can be effectively reduced, and therefore the properties of the composition (X) are less likely to be impaired even if the composition (X) is stored for a long period of time. Furthermore, the occurrence of tack in the cured product can be particularly suppressed. For example, it is preferable that the percentage of the monofunctional cationic polymerizable compound (W2) is 10% by mass or more and 35% by mass or less.

In particular, when the composition (X) contains a polyfunctional cationic polymerizable compound (W11) and a polyfunctional cationic polymerizable compound (W12), the percentage of the polyfunctional cationic polymerizable compound (W11) is preferably 30% by mass or more and 60% by mass or less, the percentage of the polyfunctional cationic polymerizable compound (W12) is preferably 15% by mass or more and 30% by mass or less, and the percentage of the monofunctional cationic polymerizable compound (W2) is preferably 15% by mass or more and 40% by mass or less, based on the total amount of the resin components. In this case, the composition (X) can achieve a good balance of good storage stability, low viscosity, and good cationic polymerization reactivity, and further achieve a good balance of excellent transparency, excellent moisture absorption, and high refractive index of the cured product.

If the cationic polymerizable compound (A) contains a compound shown in formula (3) and a compound shown in formula (16), by adjusting the ratio of the two, it is possible to appropriately adjust the ease with which the curing reaction proceeds when preparing a photocured product from composition (X), while achieving a low viscosity and improved storage stability of composition (X).

The amount of the compound shown in formula (16) is appropriately adjusted so that composition (X) has the above-mentioned properties. For example, the amount of the compound shown in formula (16) is preferably 10% by mass or more and 40% by mass or less with respect to the total amount of the resin components.

The cationic polymerizable compound (A) may contain a compound (f1) represented by the following formula (30) (hereinafter also referred to as aromatic epoxy compound (f1)). That is, the monofunctional epoxy compound (A11) may contain a compound represented by the following formula (30) in which n is 1. The polyfunctional epoxy compound (A12) may contain a compound represented by the following formula in which n is 2 to 5.

In formula (30), X is at least one selected from the group consisting of halogen, H, a hydrocarbon group, and an alkylene glycol group, and when there are multiple Xs in one molecule, they may be the same or different from each other. The hydrocarbon group is, for example, an alkyl group or an aryl group. When X is a hydrocarbon group, the number of carbon atoms of X is, for example, in the range of 1 to 10. R is a single bond or a divalent organic group. When R is a divalent organic group, the divalent organic group is, for example, an alkylene group, an oxyalkylene group, a carbonyloxyalkylene group (for example, -CO-O-CH ₂ -), or a -C(Ph) ₂ -O-CH ₂ - group. Y is H or a monovalent organic group. When Y is a monovalent organic group, the monovalent organic group is, for example, an alkyl group or an aryl group. n is a number from 1 to 5.

When the cationic polymerizable compound (A) contains an aromatic epoxy compound (f1), the aromatic epoxy compound (f1) has a low viscosity, so that the aromatic epoxy compound (f1) tends to reduce the viscosity of the composition (X). In addition, the aromatic epoxy compound (f1) is not easily volatilized, so that even if the composition (X) is stored, the composition (X) is not easily changed in composition due to the volatilization of the aromatic epoxy compound (f1). Therefore, the aromatic epoxy compound (f1) tends to increase the storage stability of the composition (X). In addition, since the aromatic epoxy compound (f1) has high reactivity, unreacted components are not easily left in the cured product, so that outgassing is not easily generated from the cured product. Furthermore, the aromatic epoxy compound (f1) tends to increase the glass transition temperature of the cured product, so that the heat resistance of the cured product is easily increased.

In addition, the aromatic epoxy compound (f1) is less likely to produce defective droplets called satellites when the composition (X) is ejected by an inkjet method.

It is preferable that R in formula (30) is a single bond or an alkylene group. When n in formula (30) is 2 or 3, it is preferable that at least one of the multiple R in formula (30) is a single bond or an alkylene group. In these cases, the reactivity of the aromatic epoxy compound (f1) tends to be high, and therefore the curability of composition (X) tends to be high when composition (X) is irradiated with ultraviolet light.

The aromatic epoxy compound (f1) preferably contains at least one compound selected from the group consisting of the compounds represented by the following formulas (301) to (318):

In particular, it is preferable that the aromatic epoxy compound (f1) contains at least one component selected from the group consisting of the compounds represented by the formulas (301) to (305), (312), (314) and (318). These compounds tend to have high reactivity because at least one epoxy group (oxirane) in the compound is bonded to the benzene ring via a single bond or an alkylene group, and therefore tend to enhance the curability of the composition (X).

The percentage of the aromatic epoxy compound (f1) relative to the total amount of the cationic polymerizable compound (A) is preferably 5% by mass or more. In this case, the above-mentioned effect of the aromatic epoxy compound (f1) is particularly likely to be obtained. This percentage is also preferably 95% by mass or less. In this case, the storage properties of the composition (X) tend to be good. This percentage is more preferably 10% by mass or more and 90% by mass or less, and even more preferably 20% by mass or more and 85% by mass or less.

It is also preferable that the cationic polymerizable compound (A) contains a compound (f2) having an oxyalkylene skeleton. The oxyalkylene skeleton is a linear skeleton consisting of one or more linear oxyalkylene units.

When the cationic polymerizable compound (A) contains the compound (f2), the compound (f2) has a low viscosity, and therefore the compound (f2) tends to reduce the viscosity of the composition (X). In addition, the compound (f2) is not easily volatilized, and therefore, even when the composition (X) is stored, the composition (X) is not easily changed in composition due to the volatilization of the aromatic epoxy compound (f1). Therefore, the compound (f2) tends to increase the storage stability of the composition (X).

In addition, compound (f2) is less likely to produce defective droplets called satellites when composition (X) is discharged by the inkjet method. Furthermore, compound (f2) can make it difficult for satellites to be produced even if the speed of droplets discharged by the inkjet method is increased. Therefore, although it depends on the inkjet conditions, it is possible to make the discharge speed of droplets by the inkjet method 4 m/s or more without producing satellites, for example. If the droplet speed can be increased, the trajectory of the droplets is less susceptible to disturbances, so that the dimensional accuracy of the cured product produced from composition (X) can be improved. Furthermore, compound (f2) can increase the storage stability of composition (X) as described above, so that the characteristic of composition (X) of being less likely to produce satellites is easily maintained even if composition (X) is stored for a long period of time.

It is particularly preferable that the oxyalkylene skeleton contains a structure of "-C-C-O-", i.e., an oxymethylene unit. In this case, satellites are particularly unlikely to occur, and even if the driving frequency is changed when ejecting composition (X) by an inkjet method, satellites are unlikely to occur. In addition, compound (f2) is less likely to volatilize and is more likely to have a lower viscosity, and furthermore, the affinity (wettability) of composition (X) to inorganic materials is likely to be increased.

The number of oxyalkylene units in the oxyalkylene skeleton of compound (f2) is preferably 1 or more and 8 or less. In this case, compound (f2) tends to have a lower viscosity, making it particularly unlikely for satellites to form, and the crosslink density of the cured product tends to be high, making the glass transition temperature of the cured product particularly high. The number of oxyalkylene units is more preferably 1 or more and 6 or less, and even more preferably 1 or more and 4 or less.

In addition, the oxyalkylene units in the oxyalkylene skeleton of compound (f2) may have a substituent group other than hydrogen bonded thereto. For example, the oxymethylene units contained in the oxyalkylene skeleton may have the structure "-CH(CH3)-CH2-O-".

The percentage of compound (f2) is preferably 10% by weight or more relative to the cationically polymerizable compound (A). In this case, the inkjet properties are good and the wettability to the substrate is good. It is also preferable that this percentage is 70% by weight or less. In this case, the glass transition temperature can be sufficiently increased. This percentage is more preferably 15% by weight or more and 60% by weight or less, and even more preferably 20% by weight or more and 50% by weight or less.

Compound (f2) contains at least one compound selected from, for example, compound (f21) having an oxyalkylene skeleton and an epoxy group, and compound (f22) having an oxyalkylene group and an oxetane group. That is, epoxy compound (A11) can contain compound (f21). Also, oxetane compound (A12) can contain compound (f22).

Compound (f21) contains at least one compound selected from the group consisting of the compound shown in formula (1b), the compound shown in formula (4), the compound shown in formula (5), the compound shown in formula (6), the compound shown in formula (7), the compound shown in formula (8), the compound shown in formula (13), and the compound shown in formula (14). Note that the components that compound (f21) can contain are not limited to the above.

Compound (f22) contains at least one compound selected from the group consisting of compounds shown in formula (3), compounds shown in formula (12), compounds shown in formula (16), and compounds shown in formula (17). Note that the components that compound (f22) may contain are not limited to the above.

It is also preferable that the cationic polymerizable compound (A) contains the epoxy compound (A1) and the above-mentioned compound (f22). When the cationic polymerizable compound (A) contains the epoxy compound (A1) and the compound (f22), the curability of the composition (X) when the composition (X) is irradiated with ultraviolet light is easily increased, and the composition (X) is less likely to be cured too rapidly at this time, so that the cured product is less likely to have a deterioration in transparency due to white turbidity. In this case, the percentage of the compound (f22) to the cationic polymerizable compound (A) is preferably 20% by mass or more. In this case, the compound (f22) is particularly easy to reduce the viscosity of the composition (X) and is particularly easy to increase the storage stability of the composition (X). Furthermore, the compound (f22) is particularly easy to increase the curability of the composition (X). It is also preferable that the percentage of the compound (f22) is 90% by mass or less. In this case, the curability of the cured product can be sufficiently increased. The percentage of compound (f22) is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less. In this case, the percentage of the epoxy compound is preferably 10% by mass or more and 90% by mass or less, more preferably 20% by mass or more and 80% by mass or less, and even more preferably 25% by mass or more and 75% by mass or less, based on the total amount of the cationic polymerizable compound (A). In these cases, the unreacted groups in the cured product can be sufficiently reduced, and the curability of the cured product can be sufficiently increased.

It is preferable that the epoxy compound (A1) contains a compound having at least one oxirane ring that does not constitute a glycidyl ether group. In this case, the epoxy compound (A1) is particularly likely to enhance the curability of the composition (X). It is more preferable that the epoxy compound (A1) contains a compound having two or more oxirane rings that do not constitute a glycidyl ether group. It is also preferable that the epoxy compound (A1) contains a compound that does not have a glycidyl ether group. It is particularly preferable that the epoxy compound (A1) contains a compound that has two or more oxirane rings that do not constitute a glycidyl ether group and does not have a glycidyl ether group.

It is particularly preferred that the cationic polymerizable compound (A) contains the compound (f2) and the epoxy compound (A1), and that the epoxy compound (A1) further contains the aromatic epoxy compound (f1) described above. In this case, the composition (X) is particularly likely to have excellent storage stability, and when the composition (X) is discharged by the inkjet method, defective droplets called satellites are particularly unlikely to be generated. Furthermore, even if the speed of the droplets discharged by the inkjet method is increased, satellites are particularly unlikely to be generated. Furthermore, even if the composition (X) is stored for a long period of time, the characteristic of the composition (X) that satellites are not likely to be generated is particularly likely to be maintained. In this case, it is particularly preferred that the compound (f2) contains the compound (f22).

The total percentage of the aromatic epoxy compound (f1) and the compound (f22) relative to the cationic polymerizable compound (A) is preferably 55% by mass or more. In this case, the effect of the combination of the aromatic epoxy compound (f1) and the compound (f22) is particularly pronounced. This percentage is more preferably 60% by mass or more, and even more preferably 70% by mass or more. It is particularly preferable that the cationic polymerizable compound (A) contains only the aromatic epoxy compound (f1) and the compound (f22).

There are no particular limitations on the photocationic polymerization initiator (B) as long as it is a catalyst that generates a protonic acid or a Lewis acid upon irradiation with light. The photocationic polymerization initiator (B) can contain at least one of an ionic photoacid-generating cationic curing catalyst and a nonionic photoacid-generating cationic curing catalyst.

The ionic photoacid generating cationic curing catalyst can contain at least one of onium salts and organometallic complexes. Examples of onium salts include aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts. Examples of organometallic complexes include iron-arene complexes, titanocene complexes, and arylsilanol-aluminum complexes. The ionic photoacid generating cationic curing catalyst can contain at least one of these components.

The non-ionic photoacid generating cationic curing catalyst may contain at least one component selected from the group consisting of, for example, nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenolsulfonic acid esters, diazonaphthoquinones, and N-hydroxyimide phosphonates. Note that the components that the non-ionic photoacid generating cationic curing catalyst may contain are not limited to the above.

More specific examples of the compound that can contain the photocationic polymerization initiator (B) include Midori Chemical's DPI series (105, 106, 109, 201, etc.), BI-105, MPI series (103, 105, 106, 109, etc.), BBI series (101, 102, 103, 105, 106, 109, 110, 200, 210, 300, 301, etc.), and TSP series. Series (102, 103, 105, 106, 109, 200, 300, 1000, etc.), HDS-109, MDS series (103, 105, 109, 203, 205, 209, etc.), BDS-109, MNPS-109, DTS series (102, 103, 105, 200, etc.), NDS series (103, 105, 155, 165, etc.), DAM series (1 01, 102, 103, 105, 201, etc.), SI series (105, 106, etc.), PI-106, NDI series (105, 106, 109, 1001, 1004, etc.), PAI series (01, 101, 106, 1001, 1002, 1003, 1004, etc.), MBZ-101, PYR-100, NB series (101, 201, etc.), NAI series Series (100, 1002, 1003, 1004, 101, 105, 106, 109, etc.), TAZ series (100, 101, 102, 103, 104, 107, 108, 109, 110, 113, 114, 118, 122, 123, 203, 204, etc.), NBC-101, ANC-101, TPS-Acetate, DTS-Acetate, Di-Boc Bisphinol A, tert-Butyl lithocholate, tert-Butyl deoxycholate, tert-Butyl cholate, BX, BC-2, MPI-103, BDS-105, TPS-103, NAT-103, BMS -105, and TMS-105;
Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990, and Cyracure UVI-950 manufactured by Union Carbide Corporation, USA;
Irgacure 250, Irgacure 261, and Irgacure 264 manufactured by BASF;
Ciba-Geigy CG-24-61;
ADEKA OPTOMER SP-150, ADEKA OPTOMER SP-151, ADEKA OPTOMER SP-170, and ADEKA OPTOMER SP-171 manufactured by ADEKA Corporation;
DAICAT II manufactured by Daicel Corporation;
UVAC1590 and UVAC1591 manufactured by Daicel-Cytec Co., Ltd.;
CI-2064, CI-2639, CI-2624, CI-2481, CI-2734, CI-2855, CI-2823, CI-2758, and CIT-1682 manufactured by Nippon Soda Co., Ltd.;
PI-2074, tetrakis(pentafluorophenyl)borate toluylcumyl iodonium salt from Rhodia;
FFC509 manufactured by 3M;
CD-1010, CD-1011 and CD-1012 manufactured by Sartomer Corporation, USA;
CPI-100P, CPI-101A, CPI-110P, CPI-110A, and CPI-210S manufactured by San-Apro Ltd., and UVI-6992 and UVI-6976 manufactured by The Dow Chemical Company. The photocationic polymerization initiator (B) can contain at least one compound selected from the group consisting of these compounds.

The percentage of the photocationic polymerization initiator (B) relative to the cationic polymerizable compound (A) is preferably 1.5% by mass or less. In this case, the composition (X) can have good storage stability, and the manufacturing cost can be reduced by not containing an excessive amount of the photocationic polymerization initiator (B). In addition, in this embodiment, as described above, the percentage of the total amount of impurity ions in the epoxy compound (A1) is 20% by mass or less, so that the reactivity of the composition (X) is increased, and even if the percentage of the photocationic polymerization initiator (B) is 1.5% by mass or less, high reactivity is easily obtained. Therefore, it is easy to achieve both high reactivity and good storage stability of the composition (X). The percentage of the photocationic polymerization initiator (B) is more preferably 1.2% by mass or less, and even more preferably 1.0% by mass or less. In addition, the percentage of the photocationic polymerization initiator (B) is preferably 0.3% by mass or more. In this case, the composition (X) can have particularly good cationic polymerization reactivity. The percentage of the photocationic polymerization initiator (B) is preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more.

The composition (X) may contain a sensitizer (C). The sensitizer (C) contains, for example, either one or both of 9,10-dibutoxyanthracene and 9,10-diethoxyanthracene. The percentage of the sensitizer (C) relative to the total amount of the resin components is preferably in the range of more than 0 mass% and not more than 1 mass%. In this case, the sensitizer (C) is less likely to inhibit the transparency of the cured product, and therefore the cured product can have good transparency. It is more preferable that the amount of the sensitizer (C) is more than 0 mass% and not more than 0.8 mass% relative to the total amount of the resin components.

The composition (X) may further contain a moisture absorbent (D). When the composition (X) contains the moisture absorbent (D), the cured product can have excellent moisture absorption. It is preferable that the average particle size of the moisture absorbent (D) is 200 nm or less. In this case, the cured product can have high transparency despite containing the moisture absorbent (D). In addition, particularly when the composition (X) is discharged by an inkjet method, if the average particle size of the moisture absorbent (D) is 200 nm or less, there is an advantage that the composition (X) is less likely to clog the nozzle. Furthermore, if the average particle size of the moisture absorbent (D) is 200 nm or less, the moisture absorbent (D) is less likely to impair the smoothness of the surface of the optical component made from the composition (X). Therefore, the surface of the optical component can have good smoothness.

The moisture absorbent (D) 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 (D) contains zeolite particles.

The average particle size of the moisture absorbent (D) 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 (D) 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 from Microtrac Bell Co., Ltd. can be used. It is also preferable that the cumulative 90% diameter (D90) of the moisture absorbent (D) is 100 nm or less. In this case, the cured product can have particularly high transparency.

The percentage of the moisture absorbent (D) relative to the total amount of the composition (X) is preferably 1% by mass or more and 20% by mass or less. If the percentage of the moisture absorbent (D) is 1% by mass or more, the cured product can have particularly high moisture absorption. If the percentage of the moisture absorbent (D) 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 that can be ejected by an inkjet method. The percentage of the moisture absorbent (D) is more preferably 3% by mass or more, and particularly preferably 5% by mass or more. The percentage of the moisture absorbent (D) 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 (D).

When the composition (X) contains the moisture absorbent (D), the composition (X) may further contain a dispersant (E). The dispersant (E) is a surfactant that can be adsorbed to the moisture absorbent (D). The dispersant (E) has, for example, an adsorption group (also called an anchor) that can be adsorbed to particles of the moisture absorbent (D), and a tail that is a chain-like or comb-like molecular skeleton that adheres to the particles of the moisture absorbent (D) when the adsorption group is adsorbed to the particles. The dispersant (E) contains at least one component selected from the group consisting of 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.

When the composition (X) contains the dispersant (E), the moisture absorbent (D) can be well dispersed in the composition (X) and the cured product. Therefore, even though the cured product and the optical component contain the moisture absorbent (D), the transparency of the cured product and the optical component is not easily reduced by the moisture absorbent (D). In addition, the dispersant (E) can effectively suppress the aggregation of the moisture absorbent (D) during storage of the composition (X). Therefore, the storage stability of the composition (X) is not easily reduced by the moisture absorbent (D). Furthermore, the adhesion between the cured product and the silicon nitride and silicon oxide is not easily reduced by the dispersant (E). This is thought to be because the dispersant (E) is easily adsorbed to the moisture absorbent (D) as described above, and therefore the dispersant (E) is not easily affected by the interface between the cured product and the silicon nitride and silicon oxide. Therefore, the optical component can have high adhesion to the glass substrate. In addition, silicon nitride and silicon oxide are sometimes used as materials for the passivation layer 6 in the light-emitting device 1. Therefore, when the passivation layer 6 is made of silicon nitride or silicon oxide, optical components such as the encapsulant 5 can have high adhesion to the passivation layer 6.

The structure of the light-emitting device 1 will be described. The light-emitting device 1 includes a light source and an optical component that transmits the light emitted by the light source. For example, the light-emitting device 1 includes a light-emitting element 4, and a sealant 5 and a passivation layer 6 that cover the light-emitting element 4. In this case, the light-emitting element 4 is the light source, the sealant 5 is the optical component, and the passivation layer 6 is an inorganic layer. The sealant 5 and the passivation layer 6 overlap each other.

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 is an abbreviation for electroluminescence.

An 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 includes 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 passivation layer 6 and a sealing material 5 that cover the light-emitting element 4.

The support substrate 2 is made of, for example, but not limited to, a resin material. 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. The light-emitting element 4 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 passivation layer 6 is preferably made of silicon nitride or silicon oxide, and is particularly preferably made of silicon nitride. In the example shown in FIG. 1, 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 covering 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.

A method for producing the encapsulant 5 using 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 ultraviolet light to harden it, 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 20 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 20 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 of 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 7 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, for example, by an inkjet method to form 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. Next, the coating film of composition (X) is cured by irradiating it with ultraviolet light to form the encapsulant 5.

When irradiating composition (X) with ultraviolet light, composition (X) may be irradiated with ultraviolet light in an atmosphere containing oxygen, such as an air atmosphere, or composition (X) may be irradiated with ultraviolet light in an inert atmosphere, such as a nitrogen atmosphere.

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

As described above, in this embodiment, it is possible to prevent a decrease in luminous efficiency caused by the passivation layer 6 and the sealing material 5 in the light-emitting device 1.

The thickness of the sealing material 5 is, for example, 1 μm or more and 20 μm or less. The thickness of the sealing material 5 may be 15 μm or less. In this case, by thinning the sealing material 5, the light-emitting device 1 can be thinned, and a bendable light-emitting device 1 can be obtained. Even if the thickness of the sealing material 5 is 10 μm or less, the composition (X) can have high curability, so that the sealing material 5 can have high barrier properties. It is more preferable that the thickness of the sealing material 5 is 8 μm or less. In order to effectively suppress moisture to the light-emitting element 4 by the sealing material 5, the thickness of the sealing material 5 is preferably 3 μm or more, and more preferably 5 μm or more.

The thickness of the passivation layer 6 overlapping the sealing material 5 is, for example, 0.1 μm or more and 2 μm or less. When the passivation layer 6 includes the first passivation layer 61 and the second passivation layer 62 as described above, it is preferable that the thickness of each of the first passivation layer 61 and the second passivation layer 62 is 0.1 μm or more and 2 μm or less, and more preferably 0.1 μm or more and 1 μm or less. As described above, in this embodiment, since the curability of the composition (X) is high, the sealing material 5 can have high barrier properties, so that even if the thickness of the passivation layer 6 is 1 μm or less, the penetration of moisture into the light-emitting element 4 can be suppressed. By reducing the thickness of the passivation layer 6 in this way, it becomes easier to realize a foldable light-emitting device 1.

The use of the composition (X) according to this embodiment is not limited to the preparation of the encapsulant 5 for the light-emitting element 4. The composition (X) can be used to prepare various optical components that transmit light emitted by a light source. For example, the optical component may be a color resist. That is, for example, a phosphor may be contained in the composition (X), and a color resist in a color filter may be prepared from this composition (X). This color filter can be provided in a display device such as an organic EL display or a micro LED display, which is a light-emitting device.

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

1. Preparation of Compositions The 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 the following components is a value measured using a rheometer (manufactured by Anton Paar Japan, model number DHR-2) at a temperature of 25°C and a shear rate of 1000 s ^-1 . The impurity ion content of the following components is a ratio of the total amount of impurity ions, and is a value measured as follows. A sample solution is obtained by thoroughly mixing 10 g of the target component with 100 g of ion-exchanged water. The sample solution is placed in a constant temperature bath at 95°C for 15 minutes, and then returned to room temperature, and then the impurity ions in the sample solution are measured using an ion chromatograph. The ratio of the total amount of potassium ions, calcium ions, sodium ions, magnesium ions, and ammonium ions in the impurity ions in the sample solution obtained in this way to the mass (10 g) of the target component is calculated as the impurity content. The impurity ion content in an epoxy compound may vary depending on the manufacturing lot even if the product number is the same.
-THI-DE/impurity ions 35 ppm: manufactured by ENEOS Corporation, product number THI-DE, compound represented by formula (20a), boiling point 260° C., viscosity 20 mPa·s, impurity ion content 35 ppm by mass.
-THI-DE/purified product, impurity ion 15 ppm: The above THI-DE and the same amount of ion-exchanged water were mixed in a disperser at a rotation speed of 500 rpm for 1 hour, and the resulting solution was distilled twice to be purified. Impurity ion content 15 ppm by mass.
-THI-DE/purified product, impurity ion 25 ppm: The above THI-DE and the same amount of ion-exchanged water were mixed in a disperser at a rotation speed of 500 rpm for 1 hour, and the resulting solution was distilled and purified. Impurity ion content 25 ppm by mass.
- D1586 / impurity ion 38 ppm: 1,7-octadiene diepoxide, manufactured by Tokyo Chemical Industry Co., Ltd., product number D1586, boiling point 240°C, viscosity 3 mPa·s, impurity ion content 38 ppm by mass.
- D1586/purified product, impurity ion 19 ppm: The above D1586 was mixed with the same amount of ion-exchanged water in a disperser at 500 rpm for 1 hour, and the resulting solution was distilled twice to refine it. Impurity ion content 19 ppm by mass.
-OXT-221: manufactured by Toagosei, product number OXT-221, compound represented by formula (3), boiling point 275°C, viscosity 11 mPa·s.
-OXT-212: Manufactured by Toagosei, product number OXT-212, compound represented by formula (3), boiling point 255°C, viscosity 5 mPa·s.
- CPI-210S: a triarylsulfonium salt type photoacid generator manufactured by San-Apro Co., Ltd., anion species (Rf) _n PF _6-n ^- , product number CPI-210S.
-UVS1101: 9,10-diethoxyanthracene, manufactured by Kawasaki Chemical Industries, Ltd., product number UVS1101.

2. Evaluation Tests The following evaluation tests were carried out for the Examples, Reference Examples, and Comparative Examples. The results are shown in the table below. Note that for Comparative Example 2, some evaluations could not be carried out because the composition could not be sufficiently cured under the test conditions.

(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) Volatility Using a thermogravimetric analyzer, the weight change rate was measured when the composition was heated for 30 minutes at 100° C. As a result, the weight change rate was rated as "A" when it was 10% by mass or less, "B" when it was more than 10% by mass and 20% by mass or less, and "C" when it was more than 20% by mass.

(3) Inkjet properties The composition was placed in a cartridge of an inkjet printer (manufactured by Ricoh Co., Ltd., model number MH2420), 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. The appearance of the droplets of the composition being discharged from the nozzle was photographed with a high-speed camera, and it was confirmed whether the droplets separated and satellites were generated. As a result, the case where the droplets did not separate was evaluated as "A", the case where the satellites separated from the original droplets and then integrated with the original droplets to form one droplet again was evaluated as "B", and the case where the satellites separated from the original droplets and did not integrate with each other was evaluated as "C".

(4) Curability The composition was applied to prepare a coating film having a thickness of 10 μm and a coating film having a thickness of 5 μm. The coating film was irradiated with ultraviolet light under atmospheric conditions at an irradiation intensity of 3 W/cm ² and an integrated light quantity of 1500 mJ/cm ² using an LED-UV irradiator (model number E075IIHD, peak wavelength 395 nm) manufactured by Ushio Inc. A finger touch test was performed on the coating film after irradiation with ultraviolet light. If no tack was observed, the coating film was judged to have cured, and if tack was observed, the coating film was judged not to have cured. As a result, if both the 10 μm-thick coating film and the 5 μm-thick coating film were cured, the coating film was rated as "A", if the 10 μm-thick coating film was cured but the 5 μm-thick coating film was not cured, the coating film was rated as "B", and if neither the 10 μm-thick coating film nor the 5 μm-thick coating film was cured, the coating film was rated as "C".

The fact that a coating film with a thickness of 5 μm hardens is presumably because the composition is less susceptible to polymerization inhibition caused by water in the air, and therefore hardening of the coating film is less likely to be inhibited even if the ratio of the surface area of the coating film to the volume of the coating film is large.

(5) Glass Transition Temperature A coating film was prepared by coating the composition, and the coating film was photocured by irradiating the coating film with ultraviolet light under an atmospheric condition at an irradiation intensity of 5 W/ ^cm2 and an accumulated light quantity of 5000 mJ/ ^cm2 using a Unijet E075IIHD (peak wavelength 395 nm) manufactured by Ushio Inc., to prepare a film having a thickness of 200 μm. The glass transition temperature of a sample cut out from the film was measured at a heating rate of 5° C./min using a viscoelasticity measuring device (manufactured by Hitachi High-Tech Science Corporation, model number DMA7100).

(6) Outgassing Evaluation The outgassing when the cured product of the composition was heated was sampled by the headspace method and measured by gas chromatography. In detail, 100 mg of the composition was first placed in a headspace vial with a volume of 22 mL. Next, the composition was cured by irradiating the composition with ultraviolet light under atmospheric conditions at an irradiation intensity of 5 W/cm ² and an accumulated light quantity of 1500 mJ/cm ² using a Unijet E075IIHD (peak wavelength 395 nm) manufactured by Ushio Electric Co., Ltd., and then the vial was sealed. Next, the composition was heated at 100° C. for 30 minutes, and then the gas phase portion in the vial was introduced into a gas chromatograph for analysis. As a result, the concentration of the outgassing generated from the composition was specified based on the peak area of the obtained gas chromatogram. The concentration of the outgassing is the volume fraction of the 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 standard substance. Specifically, two standard samples with toluene concentrations of 1000 ppm and 100 ppm were prepared by volatilizing toluene in a vial. Each standard sample was introduced into a gas chromatograph for analysis. From the peak areas of the two chromatograms obtained in this way, the relationship between peak area and concentration was determined, and the outgassing concentration was determined based on this result. If the outgassing concentration (volume fraction) is 100 ppm or less, it can be determined that the amount of outgassing is low.

(7) Transmittance The composition was applied onto a silicon nitride plate, and then cured by irradiating the composition with ultraviolet light in the atmosphere using an LED-UV irradiator (model number E075IIHD, peak wavelength 395 nm) manufactured by Ushio Inc. under conditions of an irradiation intensity of 3 W/ ^cm2 and an accumulated light quantity of 1500 mJ/ ^cm2 . This produced a film with a thickness of 10 μm. The transmittance of this film to light with a wavelength of 430 nm was measured. A spectrophotometer (U-4100 manufactured by Hitachi, Ltd.) was used for the measurement.

(8) Durability A film was prepared using the same method and conditions as in the above "(7) Transmittance". This film was exposed to conditions of 85°C and 85% RH for 1000 hours, and then the transmittance of the film was measured. As a result, the film was rated as "A" when the transmittance was 97% or more, "B" when the transmittance was 95% or more, and "C" when the transmittance was 95% or less.

(9) Storage Stability The composition was irradiated with ultraviolet light having a peak wavelength of 395 nm using a UV irradiator (manufactured by CCS, model number CKL-200) under conditions of an irradiation intensity of 100 mW/ ^cm2 and an integrated light quantity of 1.5 J/ ^cm2 . The amount of heat generated by the composition upon irradiation with ultraviolet light was measured using a DSC (manufactured by SII, model number 7020).

The composition was also left at 40°C for 4 weeks, after which the heat generation of the composition was measured under the same conditions as above.

When the rate of change in heat generation due to leaving the composition standing was less than 10%, it was rated as "A", when it was 10% or more but less than 20%, it was rated as "B", and when it was 20% or more, it was rated as "C". The smaller the rate of change, the less likely it is that the reaction of the components in the composition will proceed when the composition is left standing.

Claims (9)

Contains a cationic polymerizable compound (A) and a photocationic polymerization initiator (B),
The cationically polymerizable compound (A) contains only an epoxy compound (A1) and an oxetane compound (A2) ,
the mass ratio of the epoxy compound (A1) to the oxetane compound (A2) is from 20:80 to 60:40;
the total amount of potassium ions, calcium ions, sodium ions, magnesium ions and ammonium ions in the epoxy compound (A1) is 20 ppm by mass or less based on the entire epoxy compound (A1);
Formed by the inkjet method,
For manufacturing optical components.
UV curable resin composition. The ultraviolet-curable resin composition according to claim 1, wherein at least one of the viscosity at 25°C and the viscosity at 40°C is 20 mPa·s or less. The percentage of the photocationic polymerization initiator (B) relative to the ultraviolet curable resin composition is 1.5 mass% or less.
The ultraviolet-curable resin composition according to claim 1 or 2. The rate of outgassing generated when the cured product of the ultraviolet curable resin composition is heated at 100° C. for 30 minutes is 100 ppm or less.
The ultraviolet-curable resin composition according to claim 1 . The transmittance of the cured product of the ultraviolet curable resin composition to light having a wavelength of 430 nm is 95% or more when the thickness dimension is 10 μm.
The ultraviolet-curable resin composition according to claim 1 . A cured product of the ultraviolet-curable resin composition according to any one of claims 1 to 5.
Optical components. A method for producing an optical component, comprising: molding the ultraviolet-curable resin composition according to claim 1 by an inkjet method; and curing the ultraviolet-curable resin composition by irradiating it with ultraviolet light. A light source and an optical component that transmits light emitted by the light source, the optical component including a cured product of the ultraviolet-curable resin composition according to any one of claims 1 to 5.
Light emitting device. A method for manufacturing a light emitting device including a light source and an optical component that transmits light emitted by the light source, comprising the steps of:
The optical component is manufactured by the method of claim 7.
A method for manufacturing a light emitting device.

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