WO2024101411A1 - Curable composition for organic el elements, cured product for organic el elements and method for producing same, organic el element, and polymer - Google Patents

Abstract

Disclosed is a curable composition for organic EL elements, the curable composition containing (A) a polymer that comprises a structural unit derived from a compound having an acidic group, and (B) a photosensitive compound, wherein: the polymer (A) comprises a structural unit (I) that is derived from an aromatic vinyl compound and a structural unit (II) that is derived from a maleimide compound, while containing, as the compound having an acidic group, at least one compound that is selected from the group consisting of an aromatic vinyl compound and a maleimide compound; and the ratio of the sum of the structural unit (I) and the structural unit (II) in the polymer (A) is 70% by mole or more relative to all structural units in the polymer (A).

Description

CURABLE COMPOSITION FOR ORGANIC EL DEVICE, CURED PRODUCT FOR ORGANIC EL DEVICE AND METHOD FOR PRODUCING SAME, ORGANIC EL DEVICE, AND POLYMER

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to Japanese Patent Application No. 2022-180340, filed on November 10, 2022, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a curable composition for an organic EL device, a cured product for an organic EL device and a method for producing the same, an organic EL device, and a polymer.

An organic electroluminescence element (organic EL element) is a light-emitting element that has a layered structure including an anode, an organic light-emitting layer, and a cathode. Organic EL elements are widely used in a variety of applications, such as display devices and lighting devices.

Organic EL elements are provided with insulating cured products such as planarizing films, partition walls, and interlayer insulating films. In recent years, these cured products have been formed using curable compositions containing a polymer component and a photosensitive compound (see, for example, Patent Document 1). Specifically, a coating film formed from the curable composition is irradiated with radiation through a mask having a pattern, and then developed, and then heat-cured by heating to obtain a patterned cured film.

JP 2021-157173 A

The organic light-emitting layer in an organic EL element is prone to deterioration when it comes into contact with moisture or oxygen. For example, there are concerns that moisture may seep into the element over a long period of operation, resulting in the formation of areas that do not emit light (dark spots), and that contact with moisture or oxygen may cause a deterioration in the light-emitting characteristics. For this reason, the cured material provided in an organic EL element is required to be resistant to the passage of moisture (hereinafter referred to as "low water permeability").

In recent years, the use of flexible displays that can be deformed into various shapes, such as by bending or folding, using flexible substrates such as resin films has been considered for devices such as smartphones equipped with organic light-emitting diode (OLED). Therefore, the cured film for the organic EL element in an organic EL display may be required to have bending resistance (hereinafter also referred to as "bending resistance") that can be used with flexible displays.

Furthermore, in recent years, a technology for embedding a camera under the display (Under Display Camera: UDC technology) has been considered for mobile organic EL displays, and as a result, organic EL elements are required to realize a further multilayer wiring structure while achieving a low dielectric constant. In addition, since the cured film may be subjected to high-temperature treatment (e.g., heat treatment at 200°C or higher) during the manufacturing process of the element, the cured film applied to the organic EL element is also required to have excellent heat resistance. In particular, with the recent demand for even higher definition and quality for organic EL display devices, there is a demand for curable compositions for organic EL elements that are highly sensitive while maintaining high heat resistance and high transmittance, achieving a low dielectric constant, and providing a well-balanced improvement in poor permeability and bending resistance, and that can form a cured product with excellent element reliability.

The present disclosure has been made in consideration of the above problems, and has as its main object to provide a curable composition for organic EL elements that can form a cured product that has high sensitivity, low dielectric constant, high transmittance, and excellent heat resistance, low water permeability, and bending resistance, and can provide a highly reliable organic EL element.

The present inventors have focused on using a copolymer of an aromatic vinyl compound and a maleimide compound as the polymer component constituting the cured material of an organic EL element, and have found that the above-mentioned problems can be solved by forming a curable composition containing a specific polymer. That is, according to the present disclosure, the following curable composition for an organic EL element, a cured material for an organic EL element and a method for producing the same, an organic EL element, and a polymer are provided.

[1] A curable composition for organic EL devices, comprising [A] a polymer containing a structural unit derived from a compound having an acidic group, and [B] a photosensitive compound, the [A] polymer containing a structural unit (I) derived from an aromatic vinyl compound and a structural unit (II) derived from a maleimide compound, the compound having an acidic group containing at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and the total proportion of the structural unit (I) and the structural unit (II) in the [A] polymer is 70 mol % or more relative to the total structural units of the [A] polymer.

[2] A method for producing a cured material for an organic electroluminescence device, comprising the steps of forming a coating film using the curable composition of [1] above, irradiating at least a portion of the coating film with radiation, developing the coating film after irradiation with radiation, and heating the developed coating film.

[3] A cured product for an organic EL device formed using the curable composition according to [1] above.
[4] An organic electroluminescence device comprising the cured product according to [3] above.

[5] A polymer comprising a structural unit derived from an aromatic vinyl compound and a structural unit derived from a maleimide compound, wherein the total ratio of the structural units derived from the aromatic vinyl compound and the structural units derived from the maleimide compound is 70 mol % or more based on all structural units of the polymer, the polymer comprises a structural unit derived from a compound having an acidic group and a structural unit derived from a compound having a crosslinkable functional group, and the compound having the acidic group and the compound having the crosslinkable functional group are at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and the compound having the acidic group is at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C( ^R1 )( ^R2 )-OH" (wherein ^R1 and ^R2 are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms, and "* ¹ " represents a bond to an aromatic ring), and a maleimide.

The disclosed curable composition for organic EL devices can form a cured product that has high sensitivity, low dielectric constant, high transmittance, and excellent heat resistance, low water permeability, and bending resistance. In addition, the disclosed curable composition for organic EL devices can provide a highly reliable organic EL device.

　Below, matters related to the embodiments will be explained in detail. In this specification, a numerical range described using "~" means that the numerical range includes the numerical values before and after "~" as the lower and upper limits. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and is a unit that is contained in at least two units in the main chain structure.

In this specification, the term "hydrocarbon group" includes chain-shaped hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain-shaped hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a cyclic structure in the main chain and are composed only of a chain structure. However, the chain-shaped hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" means a hydrocarbon group that includes only an alicyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. However, the alicyclic hydrocarbon group does not have to be composed only of an alicyclic hydrocarbon structure, and also includes those that have a chain structure as a part of it. The term "aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon group does not have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part of it. The ring structure of the alicyclic hydrocarbon group and the aromatic hydrocarbon group may have a substituent composed of a hydrocarbon structure. The term "cyclic hydrocarbon group" includes alicyclic hydrocarbon groups and aromatic hydrocarbon groups.

The expression "substituted or unsubstituted p-valent hydrocarbon group (where p is an integer of 1 or more)" includes p-valent hydrocarbon groups (i.e., unsubstituted p-valent hydrocarbon groups) and groups in which p hydrogen atoms have been removed from the hydrocarbon structural portion of a substituted hydrocarbon group. Examples of substituted or unsubstituted p-valent hydrocarbon groups include alkyl groups and fluoroalkyl groups where p=1, and alkanediyl groups and fluoroalkanediyl groups where p=2. Of these, fluoroalkyl groups are "substituted monovalent hydrocarbon groups" and fluoroalkanediyl groups are "substituted divalent hydrocarbon groups." The same applies to other groups to which "substituted or unsubstituted" is added.

In this specification, "(meth)acrylic" includes "acrylic" and "methacrylic". "(meth)acryloyl" includes "acryloyl" and "methacryloyl". In this specification, it is also referred to as "epoxy group" to include oxiranyl group and oxetanyl group.

<<Curable composition for organic EL device>>
The curable composition for organic EL devices of the present disclosure (hereinafter also referred to as "the composition") is used to form an insulating cured product to be provided in an organic EL device. The composition contains a polymer (hereinafter also referred to as "polymer [A]") containing a structural unit derived from a compound having an acidic group [A], and a photosensitive compound [B]. Each component contained in the composition and other components blended as necessary will be described in detail below. Note that, unless otherwise specified, each component may be used alone or in combination of two or more.

<Polymer (A)>
The polymer [A] is a copolymer containing a structural unit (I) derived from an aromatic vinyl compound and a structural unit (II) derived from a maleimide compound. In the polymer [A], the total ratio of the structural unit (I) and the structural unit (II) is 70 mol% or more based on the total structural units of the polymer [A]. If the total ratio of the structural unit (I) and the structural unit (II) is less than 70 mol% based on the total structural units of the polymer, the heat resistance and water impermeability of the cured product obtained from the curable composition are insufficient, and the dielectric constant of the cured product tends to be too high. In order to obtain a cured product having excellent heat resistance and water impermeability and a sufficiently low dielectric constant, the total ratio of the structural unit (I) and the structural unit (II) in the polymer [A] is preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and even more preferably 90 mol% or more based on the total structural units of the polymer [A].

In the polymer [A], the aromatic vinyl compound and the maleimide compound may be arranged randomly or alternately. From the viewpoint of obtaining a sufficient effect of improving the low dielectric constant, high transmittance, heat resistance, and water impermeability of the cured product obtained from this composition, and of achieving excellent device reliability, the molar ratio of the structural unit (I) to the structural unit (II) in the polymer [A] is preferably structural unit (I)/structural unit (II) = 60/40 to 40/60, more preferably 58/42 to 42/58, and even more preferably 56/44 to 44/56.

The polymer [A] may further contain a structural unit (III) derived from a monomer (e.g., a (meth)acrylic compound, a vinyl compound, a vinyl ether compound, a conjugated diene compound, a cycloolefin) different from the aromatic vinyl compound and the maleimide compound. The proportion of the structural unit (III) in the polymer [A] is 30 mol % or less, preferably 25 mol % or less, more preferably 20 mol % or less, even more preferably 15 mol % or less, and even more preferably 10 mol % or less, based on the total structural units of the polymer [A].

(Structural unit derived from a compound having an acidic group)
The polymer [A] contains a structural unit derived from a compound having an acidic group (hereinafter, also referred to as "structural unit (A1)"). When the polymer [A] contains the structural unit (A1), it is possible to increase the solubility in an alkaline developer (alkali solubility) and to increase the curing reactivity. In this specification, "alkali soluble" means that the polymer is soluble in an alkaline aqueous solution such as a 2.38% by mass concentration aqueous solution of tetramethylammonium hydroxide.

The structural unit (A1) is not particularly limited as long as it has an acidic group. Preferred examples of the structural unit (A1) include a structural unit having a phenolic hydroxyl group, a compound having a group "* ¹ -C(R ¹ )(R ² )-OH" (wherein R ¹ and R ² are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms. "* ¹ " represents a bond to an aromatic ring. The same applies below), a structural unit having a carboxyl group, a structural unit having a sulfonic acid group, a structural unit having a sulfonamide group, a structural unit having a phosphonic acid group, and a structural unit derived from maleimide. In terms of being able to sufficiently reduce the dielectric constant of the cured product, the structural unit (A1) is preferably a structural unit derived from at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C(R ¹ )(R ² )-OH", and maleimide. In this specification, the term "phenolic hydroxyl group" refers to a hydroxy group directly bonded to an aromatic ring (for example, a benzene ring, a naphthalene ring, an anthracene ring, etc.).

（式（ａ－１）～式（ａ－３）中、Ｒ^３、Ｒ^４、Ｒ^６、Ｒ^７及びＲ^８は、互いに独立して、水素原子、メチル基、ヒドロキシメチル基、シアノ基又はトリフルオロメチル基である。Ｒ^５は、置換若しくは無置換の炭素数１～２０の（ｒ１＋１）価の炭化水素基、又は、置換若しくは無置換の炭素数２～２０の炭化水素基における炭素－炭素結合間に－Ｏ－、－ＣＯ－、－ＣＯＯ－、－ＮＨ－、－ＣＯＮＨ－若しくは－Ｓ－を含む（ｒ１＋１）価の基である。Ａ^１は、置換又は無置換の炭素数６～２０の（ｒ２＋１）価の芳香環基である。Ｘ^１及びＸ^２は、互いに独立して、フェノール性水酸基、基「＊^１－Ｃ（Ｒ^１）（Ｒ^２）－ＯＨ」、カルボキシ基、スルホン酸基、スルホンアミド基又はホスホン酸基である。ｒ１及びｒ２は、互いに独立して１又は２である。） The polymer [A] contains, as the structural unit (A1), a structural unit derived from at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds (hereinafter also referred to as "structural unit (A1-1)"). Specific examples of the structural unit (A1-1) include structural units represented by the following formula (a-1), formula (a-2), or formula (a-3).

(In formulae (a-1) to (a-3), R ³ , R ⁴ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group. ^{R 5} is a substituted or unsubstituted (r1+1)-valent hydrocarbon group having 1 to 20 carbon atoms, or a (r1+1)-valent group containing -O-, -CO-, -COO-, -NH-, -CONH- or -S- between the carbon-carbon bonds in a substituted or unsubstituted hydrocarbon group having 2 to 20 carbon atoms. A ¹ is a substituted or unsubstituted (r2+1)-valent aromatic ring group having 6 to 20 carbon atoms. X ¹ and X ² are each independently a phenolic hydroxyl group, a group "* ¹ -C(R ¹ )(R ² ) -OH", a carboxy group, a sulfonic acid group, a sulfonamide group or a phosphonic acid group. r1 and r2 are each independently 1 or 2.

In the above formulae (a-1) to (a-3), R ³ , R ⁴ , R ⁶ , R ⁷ and R ⁸ are preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability.
When ^R5 is a (r1+1)-valent hydrocarbon group, examples of the (r1+1)-valent hydrocarbon group include a chain hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, and an aromatic hydrocarbon group having 6 to 20 carbon atoms.

Examples of the (r1+1)-valent chain hydrocarbon group having 1 to 10 carbon atoms represented by ^R5 include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms and linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms. Of these, linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms are preferred.

Examples of the (r1+1)-valent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by ^R5 include groups in which (r1+1) hydrogen atoms have been removed from a monocyclic saturated alicyclic hydrocarbon, a monocyclic unsaturated alicyclic hydrocarbon, or an alicyclic polycyclic hydrocarbon having 3 to 20 carbon atoms. Specific examples of these alicyclic hydrocarbons include monocyclic saturated alicyclic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; monocyclic unsaturated alicyclic hydrocarbons such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene; and alicyclic polycyclic hydrocarbons such as bicyclo[2.2.1]heptane (norbornane), bicyclo[2.2.2]octane, tricyclo[3.3.1.1 ^3,7 ]decane (adamantane), and tetracyclo[6.2.1.1 ^3,6 .0 ^2,7 ]dodecane.

Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms and a valence of (r1+1) represented by ^R5 include groups in which (r1+1) hydrogen atoms have been removed from an aromatic ring such as benzene, naphthalene, anthracene, indene, and fluorene.

From the viewpoint of being able to enhance the heat resistance, bending resistance and water impermeability of the cured product obtained from the present composition, and being able to form crosslinking points by irradiation with radiation or application of heat, the group represented by R ⁵ is preferably a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms and having a valence of (r1+1), and more preferably a (r1+1)-valent group (aromatic ring group) having 6 to 20 carbon atoms obtained by removing (r1+1) hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic hydrocarbon. Among these, the group represented by R ⁵ is preferably a group obtained by removing (r1+1) hydrogen atoms from the ring portion of a substituted or unsubstituted benzene ring or naphthalene ring.

The aromatic ring group represented by A ¹ is a group in which (r2+1) hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

When the group represented by ^R5 or the aromatic ring group represented by ^A1 has a substituent in the ring portion, examples of the substituent include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an acyl group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, a carboxy group, a cyano group, a nitro group, etc.

^X1 and ^X2 are preferably a phenolic hydroxyl group, a group "* ¹ -C( ^R1 )( ^R2 )-OH" or a carboxy group, and from the viewpoint of obtaining a cured product with a lower dielectric constant, a phenolic hydroxyl group or a group "* ¹ -C( ^R1 )( ^R2 )-OH" is more preferable.

（式中、Ｒ^４１、Ｒ^４２及びＲ^４３は、互いに独立して、水素原子、メチル基、ヒドロキシメチル基、シアノ基又はトリフルオロメチル基である。） Further specific examples of the structural unit (A1-1) include structural units represented by the following formulas.

(In the formula, R ⁴¹ , R ⁴² and R ⁴³ are each independently a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group.)

The polymer [A] may further contain a structural unit (A1) different from the structural unit (A1-1) (hereinafter also referred to as "structural unit (A1-2)"). The monomer that gives the structural unit (A1-2) is not particularly limited as long as it is a compound that has an acidic group as well as a polymerizable group that is copolymerizable with the monomer that gives the structural unit (A1-1). Examples of the monomer that gives the structural unit (A1-2) include vinyl compounds and (meth)acrylic compounds.

Specific examples of monomers that give the structural unit (A1-2) include unsaturated monocarboxylic acids such as (meth)acrylic acid, crotonic acid, and 4-vinylbenzoic acid that give structural units having a carboxy group; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid that give structural units having a sulfonic acid group; vinyl sulfonic acid, (meth)allylsulfonic acid, and (meth)acryloyloxyethylsulfonic acid that give structural units having a phenolic hydroxyl group; and hydroxyphenyl (meth)acrylate that gives structural units having a phenolic hydroxyl group.

The content of the structural unit (A1) in the polymer [A] is preferably 12 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more, based on all structural units constituting the polymer [A], from the viewpoint of imparting good solubility in an alkaline developer. On the other hand, if the content of the structural unit (A1) is too high, the difference in solubility in an alkaline developer between the exposed and unexposed parts becomes small, and it may become difficult to obtain a good pattern shape. From this viewpoint, the content of the structural unit (A1) is preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less, based on all structural units constituting the polymer [A].

The content of the structural unit (A1-1) in the polymer [A] is preferably 10 mol % or more, more preferably 15 mol % or more, and even more preferably 20 mol % or more, based on the total structural units constituting the polymer [A], from the viewpoint of imparting good solubility in an alkaline developer to the polymer and of obtaining a curable composition capable of obtaining a cured product that is heat resistant, has a low dielectric constant, has high transmittance, and is poorly water permeable, while maintaining high sensitivity. The content of the structural unit (A1-1) is preferably 80 mol % or less, more preferably 75 mol % or less, and even more preferably 70 mol % or less, based on the total structural units constituting the polymer [A].

When the polymer [A] contains the structural unit (A1-2), the content of the structural unit (A1-2) is preferably 10 mol % or less, more preferably 5 mol % or less, even more preferably 1 mol % or less, and even more preferably 0.5 mol % or less, based on the total structural units constituting the polymer [A], from the viewpoint of obtaining a cured product that is heat resistant, has a low dielectric constant, has high transmittance, and is poorly water permeable, while maintaining high sensitivity of the composition.

The polymer [A] may further contain structural units other than the structural unit (A1) (hereinafter also referred to as "other structural units"). Examples of the other structural units include structural units having a crosslinkable functional group, structural units having an acid-dissociable group, etc.

(Structural Unit Having a Crosslinkable Functional Group)
It is preferable that the polymer [A] further contains a structural unit having a crosslinkable functional group (excluding "structural unit (A1)"; hereinafter, also referred to as "structural unit (A2)"). When the polymer [A] has a crosslinkable functional group, a cured product exhibiting superior heat resistance and bending resistance can be formed. In this specification, a structural unit that exhibits crosslinkability but has a functional group that dissociates under the action of an acid to generate an acidic group is classified as a "structural unit having an acid-dissociable group" as described below.

The crosslinkable functional group of the structural unit (A2) is preferably a group that undergoes a crosslinking reaction by light or heat. Specific examples of the crosslinkable functional group include a cyclic ether group, a cyclic thioether group, a carboxy group, a cyclic carbonate group, an alcoholic hydroxyl group, an amino group, a protected amino group, a protected isocyanate group, a polymerizable unsaturated bond group, and a hydroxyalkylamide group. [A] In order to form a crosslinked structure between or within the molecules of the polymer and to improve the heat resistance and bending resistance of the cured product, the crosslinkable functional group of the structural unit (A2) is preferably at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group, and more preferably at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and an alkoxysilyl group, in order to achieve both reactivity and storage stability.

From the viewpoint of obtaining a cured product having excellent heat resistance and water impermeability and a low dielectric constant by sufficiently increasing the amount of structural unit (I) and structural unit (II), it is preferable that the polymer [A] contains, as structural unit (A2), at least one structural unit selected from the group consisting of aromatic vinyl compounds and maleimide compounds, which is derived from a compound having a crosslinkable functional group (hereinafter also referred to as "structural unit (A2-1)").

（式（ｂ－１）及び式（ｂ－２）中、Ｒ^１３、Ｒ^１４及びＲ^１６は、互いに独立して、水素原子、メチル基、ヒドロキシメチル基、シアノ基又はトリフルオロメチル基である。Ｒ^１５は、置換若しくは無置換の炭素数１～２０の（ｒ３＋１）価の炭化水素基、又は、置換若しくは無置換の炭素数２～２０の炭化水素基における炭素－炭素結合間に－Ｏ－、－ＣＯ－、－ＣＯＯ－、－ＮＨ－、－ＣＯＮＨ－若しくは－Ｓ－を含む（ｒ３＋１）価の基である。Ａ^１１は、置換又は無置換の炭素数６～２０の２価の芳香環基である。Ｒ^１７は、単結合、置換若しくは無置換の炭素数１～２０の（ｒ４＋１）価の炭化水素基、又は、置換若しくは無置換の炭素数２～２０の炭化水素基における炭素－炭素結合間に－Ｏ－、－ＣＯ－、－ＣＯＯ－、－ＮＨ－、－ＣＯＮＨ－若しくは－Ｓ－を含む（ｒ４＋１）価の基である。Ｘ^１１及びＸ^１２は、互いに独立して架橋性官能基である。ｒ３及びｒ４は、互いに独立して１又は２である。） Specific examples of the structural unit (A2-1) include structural units represented by the following formula (b-1) or formula (b-2).

(In formula (b-1) and formula (b-2), R ¹³ , R ¹⁴ , and R ¹⁶ are each independently a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group, or a trifluoromethyl group. ^{R 15} is a substituted or unsubstituted (r3+1)-valent hydrocarbon group having 1 to 20 carbon atoms, or a (r3+1)-valent group containing -O-, -CO-, -COO-, -NH-, -CONH-, or -S- between the carbon-carbon bonds in a substituted or unsubstituted hydrocarbon group having 2 to 20 carbon atoms. ^{A 11} is a substituted or unsubstituted divalent aromatic ring group having 6 to 20 carbon atoms. R ^X17 is a single bond, a substituted or unsubstituted (r4+1)-valent hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted (r4+1)-valent group containing -O-, -CO-, -COO-, -NH-, -CONH- or -S- between the carbon-carbon bonds in a substituted or unsubstituted hydrocarbon group having 2 to 20 carbon atoms. ^X11 and ^X12 are each independently a crosslinkable functional group. r3 and r4 are each independently 1 or 2.

In the above formulae (b-1) and (b-2), R ¹³ , R ¹⁴ and R ¹⁶ are preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability.
Specific and preferred examples of R ¹⁵ include the same groups as those exemplified in the explanation of R ⁵ in the above formula (a-1).
Specific examples of R ¹⁷ include the same groups as those exemplified in the description of R ⁵ in the above formula (a-1). ^{R 17} is preferably a single bond, a substituted or unsubstituted (r4+1)-valent chain hydrocarbon group having 1 to 20 carbon atoms, or a (r4+1)-valent group containing -O-, -CO-, -COO-, -NH-, -CONH- or -S- between the carbon-carbon bonds in a substituted or unsubstituted chain hydrocarbon group having 2 to 20 carbon atoms.
Specific and preferred examples of A ¹¹ include the same groups as those exemplified in the description of A ¹ in the above formula (a-2).
Specific and preferred examples of X ¹¹ and X ¹² include the same groups as those explained above as specific and preferred examples of the crosslinkable functional group.

（式中、Ｒ^６１、Ｒ^６２及びＲ^６３は、互いに独立して、水素原子、メチル基、ヒドロキシメチル基、シアノ基又はトリフルオロメチル基である。） Further specific examples of the structural unit (A2-1) include structural units represented by the following formulas.

(In the formula, R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group.)

The polymer [A] may further contain, as the structural unit (A2), a structural unit different from the structural unit (A2-1) (hereinafter also referred to as "structural unit (A2-2)"). The monomer that gives the structural unit (A2-2) is not particularly limited as long as it is a compound that has a crosslinkable functional group as well as a polymerizable group copolymerizable with the monomer that gives the structural unit (A1) and the structural unit (A2-1), and examples thereof include (meth)acrylic compounds and vinyl compounds. Specific examples of monomers that provide the structural unit (A2-2) include glycidyl (meth)acrylate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 2-(3,4-epoxycyclohexyl)ethyl (meth)acrylate, 3,4-epoxytricyclo[5.2.1.0 ^2,6 ]decyl (meth)acrylate, (3-methyloxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)(meth)acrylate, (oxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, and the like.

The content of the structural unit (A2) in the polymer [A] is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units constituting the polymer [A], from the viewpoint of imparting good heat resistance and bending resistance to the cured product. Also, from the viewpoint of obtaining a good pattern shape, the content of the structural unit (A2) is preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 60 mol% or less, based on all structural units constituting the polymer [A].

The content of the structural unit (A2-1) in the polymer [A] is preferably 2 mol % or more, more preferably 7 mol % or more, and even more preferably 15 mol % or more, based on the total structural units constituting the polymer [A], from the viewpoint of obtaining a curable composition capable of obtaining a cured product with low dielectric constant, high transmittance, and low water permeability while maintaining high sensitivity, in addition to improving the heat resistance and bending resistance of the resulting cured product. The content of the structural unit (A2-1) is preferably 70 mol % or less, more preferably 65 mol % or less, and even more preferably 60 mol % or less, based on the total structural units constituting the polymer [A].

When the polymer [A] contains the structural unit (A2-2), the content of the structural unit (A2-2) is preferably 30 mol % or less, more preferably 15 mol % or less, even more preferably 5 mol % or less, and even more preferably 1 mol % or less, based on the total structural units constituting the polymer [A], from the viewpoint of obtaining a cured product that exhibits good heat resistance, low dielectric constant, high transmittance, poor water permeability, and bending resistance while maintaining high sensitivity of the composition.

(Structural Unit Having an Acid-Dissociable Group)
The acid dissociable group is a group that replaces a hydrogen atom of an acidic group such as a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a silanol group, or a sulfo group, and is a group that dissociates under the action of an acid. By using a photoacid generator as the photosensitive compound [B] and the polymer [A] having an acid dissociable group, the composition can be made into a chemically amplified curable composition. That is, when a part of the curable composition is irradiated with radiation, the acid dissociable group is eliminated by the acid generated by the irradiation of radiation in the exposed part to generate an acidic group, while the hydrogen atom of the acidic group remains substituted by the acid dissociable group in the unexposed part. This allows the solubility in a developer to be different between the exposed part and the unexposed part, and then the curable composition after exposure can be developed to obtain a cured product having a pattern formed thereon.

Preferred specific examples of structural units having an acid-dissociable group (hereinafter also referred to as "structural unit (A3)") include a structural unit in which an acid-dissociable group is eliminated by the action of an acid to generate a carboxyl group (hereinafter also referred to as "structural unit (A3-1)"), a structural unit in which an acid-dissociable group is eliminated by the action of an acid to generate a phenolic hydroxyl group (hereinafter also referred to as "structural unit (A3-2)"), and a structural unit in which an acid-dissociable group is eliminated by the action of an acid to generate a hydroxyl group bonded to a silicon atom (hereinafter also referred to as "structural unit (A3-3)").

Regarding the structural unit (A3-1): The structural unit (A3-1) may be a structural unit derived from a protected unsaturated carboxylic acid. The unsaturated carboxylic acid to be used is not particularly limited, but examples thereof include unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, unsaturated acid anhydrides, and unsaturated polycarboxylic acids.

Examples of the acid-dissociable group contained in the structural unit (A3-1) include a tertiary carbon-containing hydrocarbon group, an acetal-based functional group, a tertiary alkyl carbonate group, and an alkyl group-containing silyl group. Of these, a tertiary carbon-containing hydrocarbon group or an acetal-based functional group is preferred because it is easily dissociated by an acid.

（式（Ｘ－１）中、Ｒ^３４、Ｒ^３５及びＲ^３６は、次の（１）又は（２）である。（１）Ｒ^３４、Ｒ^３５及びＲ^３６は、それぞれ独立して、炭素数１～１２のアルキル基又は炭素数３～２０の１価の脂環式炭化水素基である。（２）Ｒ^３４及びＲ^３５は、互いに合わせられＲ^３４及びＲ^３５が結合する炭素原子とともに構成される炭素数４～２０の脂環式炭化水素構造を表す。Ｒ^３６は、炭素数１～１２のアルキル基、炭素数２～１２のアルケニル基又は炭素数６～２０のアリール基である。「＊」は結合手を表す。） When the acid-dissociable group is a tertiary carbon-containing hydrocarbon group, the structural unit (A3-1) preferably has a group represented by the following formula (X-1) as the protected carboxy group.

(In formula (X-1), R ³⁴ , R ³⁵ and R ³⁶ are the following (1) or (2). (1) R ³⁴ , R ³⁵ and R ³⁶ are each independently an alkyl group having 1 to 12 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. (2) R ³⁴ and R ³⁵ , taken together, represent an alicyclic hydrocarbon structure having 4 to 20 carbon atoms formed together with the carbon atom to which R ³⁴ and R ³⁵ are bonded. R ³⁶ is an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, or an aryl group having 6 to 20 carbon atoms. "*" represents a bond.)

（式（Ｘ－２）中、Ｒ^３１、Ｒ^３２及びＲ^３３は、次の（１）又は（２）である。（１）Ｒ^３１は水素原子、炭素数１～１２のアルキル基又は炭素数３～２０の１価の脂環式炭化水素基である。Ｒ^３２及びＲ^３３は、互いに独立して、炭素数１～１２のアルキル基、炭素数３～２０の１価の脂環式炭化水素基、又は炭素数７～２０のアラルキル基である。（２）Ｒ^３１は、水素原子、炭素数１～１２のアルキル基又は炭素数３～２０の１価の脂環式炭化水素基である。Ｒ^３２及びＲ^３３は、互いに合わせられＲ^３２及びＯＲ^３３が結合する炭素原子とともに構成される環状エーテル構造を表す。「＊」は結合手を表す。） When the acid-dissociable group is an acetal functional group, the structural unit (A3-1) preferably has an acetal ester structure of a carboxylic acid as the protected carboxy group, and specifically, it preferably has a group represented by the following formula (X-2):

(In formula (X-2), R ³¹ , R ³² and R ³³ are the following (1) or (2). (1) R ³¹ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ³² and R ³³ are each independently an alkyl group having 1 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. (2) R ³¹ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms. R ³² and R ³³ are combined together to represent a cyclic ether structure formed together with the carbon atom to which R ³² and OR ³³ are bonded. "*" represents a bond.)

The alkyl group having 1 to 12 carbon atoms represented by R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ and R ³⁶ may be linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 6, and more preferably 1 to 4. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms represented by R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ , and R ³⁶ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an isobornyl group, an adamantyl group, etc. Examples of the aralkyl groups having 7 to 20 carbon atoms represented by R ³² and R ³³ include a phenylmethyl group, a phenylethyl group, a methylphenylmethyl group, etc.

The alkenyl group having 2 to 12 carbon atoms represented by R ³⁶ may be linear or branched. The number of carbon atoms in the alkenyl group is preferably 2 to 6, and more preferably 2 to 4. Specific examples include an ethenyl group, a 1-propenyl group, a 2-propenyl group, and a 1-butenyl group.
Examples of the aryl group having 6 to 20 carbon atoms represented by R ³⁶ include a phenyl group, a methylphenyl group, an ethylphenyl group, and a dimethylphenyl group.

Examples of the alicyclic hydrocarbon structure having 4 to 20 carbon atoms formed by combining R ³⁴ and R ³⁵ together include a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, and a cycloheptane structure.
The cyclic ether structure formed by combining R ³² and R ³³ with each other preferably has a ring member number of 5 or more. Specific examples thereof include a tetrahydrofuran ring structure and a tetrahydropyran ring structure.

Specific examples of the group represented by the above formula (X-1) include a tert-butoxycarbonyl group, a 1,1-dimethylpropyloxycarbonyl group, a 1-methyl-1-cyclopentyloxycarbonyl group, a 1-ethyl-1-cyclopentyloxycarbonyl group, a 1-methyl-1-cyclohexyloxycarbonyl group, and a 1-ethyl-1-cyclohexyloxycarbonyl group.

In the above formula (X-2), since "-C(R ³¹ )(R ³² )(OR ³³ )" is easily dissociated by the action of an acid, R ³¹ is preferably a hydrogen atom, a methyl group or an ethyl group, and more preferably a hydrogen atom.
Specific examples of the group represented by formula (X-2) above include a 1-methoxyethoxycarbonyl group, a 1-ethoxyethoxycarbonyl group, a 1-propoxyethoxycarbonyl group, a 1-butoxyethoxycarbonyl group, a 1-cyclohexyloxyethoxycarbonyl group, a 2-tetrahydrofuranyloxycarbonyl group, a 2-tetrahydropyranyloxycarbonyl group, and a 1-phenylmethoxyethoxycarbonyl group.

Regarding the structural unit (A3-2) The acid dissociable group contained in the structural unit (A3-2) is not particularly limited as long as it is capable of generating a phenolic hydroxyl group by being eliminated by the action of an acid. From the viewpoints of the sensitivity, pattern shape, storage stability, etc. of the present composition, the acid dissociable group contained in the structural unit (A3-2) is preferably an acetal functional group, a tertiary alkyl group, or an alkyl group-containing silyl group.

（式（Ｚ－１）中、Ａｒ^１は、置換又は無置換のアリーレン基である。Ｒ^３１、Ｒ^３２及びＲ^３３は式（Ｘ－２）と同義である。「＊」は結合手を表す。） Examples of the acetal functional group that can be used in the structural unit (A3-2) include the same acid-dissociable groups that can be used in the structural unit (A3-1). Among them, a phenolic hydroxyl group protected by a group represented by "-O-C(R ³¹ )(R ³² )(OR ³³ )" (wherein R ³¹ , R ³² and R ³³ are the same as those defined in formula (X-2)) is preferred. In this case, the protected phenolic hydroxyl group contained in the structural unit (A3-2) can be represented by the following formula (Z-1).

In formula (Z-1), Ar ¹ is a substituted or unsubstituted arylene group. R ³¹ , R ³² and R ³³ are the same as in formula (X-2). "*" represents a bond.

Preferred specific examples of the group represented by "-C(R ³¹ )(R ³² )(OR ³³ )" contained in the structural unit (A3-2) include 1-alkoxyalkyl groups and 1-arylalkoxyalkyl groups, and specific examples include a 1-ethoxyethyl group, a 1-methoxyethyl group, a 1-butoxyethyl group, a 1-isobutoxyethyl group, a 1-(2-ethylhexyloxy)ethyl group, a 1-propoxyethyl group, a 1-cyclohexyloxyethyl group, a 1-(2-cyclohexylethoxy)ethyl group, and a 1-benzyloxyethyl group.
Specific examples of the tertiary alkyl group include a tert-butyl group and a 1,1-dimethylpropyl group.
Specific examples of the alkyl group-containing silyl group include a trimethylsilyl group, a triethylsilyl group, a triisopropylsilyl group, a tert-butyldimethylsilyl group, and a tert-butyldiphenylsilyl group.

Regarding the structural unit (A3-3): The structural unit (A3-3) has a functional group that is eliminated by the action of an acid to generate a silanol group (Si-OH). Specifically, the structural unit (A3-3) preferably has a group "-Si(Y ¹ )(Y ² )(Y ³ )" (wherein Y ¹ , Y ² and Y ³ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 10 carbon atoms or a phenyl group, and at least one of Y ¹ , Y ² and Y ³ is an alkoxy group having 1 to 6 carbon atoms).

Here, the alkoxy group represented by Y ¹ to Y ³ preferably has 1 to 3 carbon atoms, and is more preferably a methoxy group or an ethoxy group. The alkyl group represented by Y ¹ to Y ³ is preferably a methyl group, an ethyl group, or a propyl group. One of the groups represented by Y ¹ to Y ³ is an alkoxy group having 1 to 6 carbon atoms. The remaining group is preferably a hydroxy group, an alkoxy group having 1 to 6 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, more preferably a hydroxy group, an alkoxy group having 1 to 3 carbon atoms, or an alkyl group having 1 to 3 carbon atoms, and even more preferably an alkoxy group having 1 to 3 carbon atoms, or an alkyl group having 1 to 3 carbon atoms.

（式（３－１）、式（３－２）及び式（３－３）中、Ｘ^２１及びＸ^２２は、それぞれ独立して、ハロゲン原子、ヒドロキシ基、炭素数１～６のアルキル基又は炭素数１～６のアルコキシ基である。ｎ１は０～４の整数である。ｎ２は０～６の整数である。ただし、ｎ１が２以上の場合、複数のＸ^２１は、互いに同一又は異なる。ｎ２が２以上の場合、複数のＸ^２２は、互いに同一又は異なる。Ｒ^５０はアルカンジイル基である。Ｙ^１、Ｙ^２及びＹ^３は上記と同義である。「＊」は、結合手を表す。） The group "-Si(Y ¹ )(Y ² )(Y ³ )" is preferably bonded to a benzene ring, a naphthalene ring, or an alkyl chain. Specifically, the structural unit (A3-3) preferably has at least one selected from the group consisting of a group represented by the following formula (3-1), a group represented by the following formula (3-2), and a group represented by the following formula (3-3).

(In formula (3-1), formula (3-2), and formula (3-3), ^X21 and ^X22 each independently represent a halogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. n1 is an integer from 0 to 4. n2 is an integer from 0 to 6. However, when n1 is 2 or more, multiple ^X21 are the same as or different from each other. When n2 is 2 or more, multiple ^X22 are the same as or different from each other. ^R50 is an alkanediyl group. ^Y1 , ^Y2 , and ^Y3 are as defined above. "*" represents a bond.)

In order to improve the heat resistance and bending resistance of the cured product obtained from this composition, it is preferable that the structural unit (A3-3) has at least one type selected from the group consisting of the group represented by formula (3-1) and the group represented by formula (3-2) among the above formulas (3-1) to (3-3).

（式中、Ｒ^５１、Ｒ^５２及びＲ^５３は、互いに独立して、水素原子、メチル基、ヒドロキシメチル基、シアノ基又はトリフルオロメチル基である。） From the viewpoint of sufficiently increasing the amount of the structural unit (I) and the structural unit (II) introduced and thereby obtaining a cured product having excellent heat resistance and poor water permeability and a sufficiently low dielectric constant, the structural unit (A3) is preferably a structural unit derived from at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds. Specific examples of the structural unit (A3) include structural units represented by the following formulas.

(In the formula, R ⁵¹ , R ⁵² and R ⁵³ are each independently a hydrogen atom, a methyl group, a hydroxymethyl group, a cyano group or a trifluoromethyl group.)

When a photoacid generator is used as the photosensitive compound [B], it is preferable that the polymer [A] contains the structural unit (A3). In this case, the content of the structural unit (A3) in the polymer [A] is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on all structural units constituting the polymer [A]. The content of the structural unit (A3) is preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less, based on all structural units constituting the polymer [A]. By setting the content of the structural unit (A3) within the above range, when a photoacid generator is used as the photosensitive compound [B], it is preferable in that the sensitivity of the composition can be increased and the coating film shows better resolution.

　Other examples of monomers that provide other structural units include, in addition to the above, (meth)acrylic acid alkyl esters, (meth)acrylic acid esters having an alicyclic structure, (meth)acrylic acid esters having an aromatic ring structure, vinyl compounds having a heterocyclic structure, vinyl ether compounds, conjugated diene compounds, nitrogen-containing vinyl compounds, unsaturated dicarboxylic acid dialkyl ester compounds, cycloolefins, and aromatic vinyl compounds or N-substituted maleimide compounds that are different from the structural units (A1) to (A3).

Specific examples of the above monomers include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-lauryl (meth)acrylate, and n-stearyl (meth)acrylate;
Examples of (meth)acrylic acid esters having an alicyclic structure include cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, tricyclo[5.2.1.0 ^2,6 ]decan-8-yl (meth)acrylate, tricyclo[5.2.1.0 ^2,5 ]decan-8-yloxyethyl (meth)acrylate, isobornyl (meth)acrylate, and α-methylene-γ-butyrolactone;
Examples of (meth)acrylic acid esters having an aromatic ring structure include phenyl (meth)acrylate and benzyl (meth)acrylate;
Examples of vinyl compounds having a heterocyclic structure include tetrahydrofurfuryl (meth)acrylate, tetrahydropyranyl (meth)acrylate, 5-ethyl-1,3-dioxan-5-ylmethyl (meth)acrylate, 5-methyl-1,3-dioxan-5-ylmethyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, 2-(meth)acryloyloxymethyl-1,4,6-trioxaspiro[4,6]undecane, (γ-butyrolactone-2-yl) (meth)acrylate, glycerin carbonate (meth)acrylic acid, (γ-lactam-2-yl) (meth)acrylate, N-(meth)acryloyloxyethylhexahydrophthalimide, 2-vinyl-2-oxazoline, isopropenyloxazoline, N-vinyl-2-pyrrolidone, and itaconimide;
Examples of vinyl ether compounds include ethyl vinyl ether, butyl vinyl ether, vinyl glycidyl ether, 2-(glycidyloxy)ethyl vinyl ether, and 4-(glycidyloxy)butyl vinyl ether;
Conjugated diene compounds include 1,3-butadiene and isoprene;
Nitrogen-containing vinyl compounds include (meth)acrylonitrile and (meth)acrylamide;
As the unsaturated dicarboxylic acid dialkyl ester compound, diethyl itaconate, etc.
Examples of cycloolefins include cyclopentene, cyclohexene, cycloheptene, norbornene, etc. Examples of monomers that provide other structural units include, in addition to the above, monomers such as vinyl chloride, vinylidene chloride, vinyl acetate, etc.

In addition, examples of aromatic vinyl compounds or N-substituted maleimide compounds that are different from the structural units (A1) to (A3) include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 5-t-butyl-2-methylstyrene, divinylbenzene, trivinylbenzene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, diphenylethylene, vinylnaphthalene, and vinylpyridine;
Examples of the N-substituted maleimide compounds include N-cyclohexylmaleimide, N-cyclopentylmaleimide, N-(2-methylcyclohexyl)maleimide, N-(4-methylcyclohexyl)maleimide, N-(4-ethylcyclohexyl)maleimide, N-(2,6-dimethylcyclohexyl)maleimide, N-norbornylmaleimide, N-tricyclodecylmaleimide, N-adamantylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, N-(4-methylphenyl)maleimide, N-(4-ethylphenyl)maleimide, N-(2, 6-dimethylphenyl)maleimide, N-benzylmaleimide, N-naphthylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-n-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, N-s-butylmaleimide, N-t-butylmaleimide, N-n-pentylmaleimide, N-n-hexylmaleimide, N-n-heptylmaleimide, N-n-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide, and N-2-ethylhexylmaleimide.

From the viewpoint of further improving the water impermeability, heat resistance, and bending resistance of the cured product, N-substituted maleimide compounds having a cyclic structure in the substituted portion are preferred, and compounds having a benzene ring or cyclohexane ring are more preferred.

When the polymer [A] contains structural units other than the structural units (A2) and (A3) as other structural units, the content of the structural units is preferably 70 mol % or less, and more preferably 60 mol % or less, based on the total structural units of the polymer [A].

(Synthesis of polymer [A])
The polymer [A] can be produced, for example, by using a monomer capable of introducing each of the structural units described above in a suitable solvent in the presence of a polymerization initiator, according to a known method such as radical polymerization. Examples of the polymerization initiator include an azo compound and an organic peroxide. Examples of the azo compound include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(isobutyric acid) dimethyl. Examples of the organic peroxide include benzoyl peroxide and di-tert-butyl peroxide. The proportion of the polymerization initiator used is preferably 0.01 to 30 parts by mass relative to 100 parts by mass of the total amount of the monomers used in the reaction. Examples of the polymerization solvent include alcohols, ethers, ketones, esters, and hydrocarbons. The amount of the polymerization solvent used is preferably such that the total amount of the monomers used in the reaction is 0.1 to 60% by mass relative to the total amount of the reaction solution.

In the polymerization, the reaction temperature is usually 30°C to 180°C. The reaction time can be set depending on the type of polymerization initiator and monomer, and the reaction temperature. The reaction time is usually 0.5 to 10 hours. The polymer obtained by the polymerization reaction may be used in the preparation of the present composition while still dissolved in the reaction solution, or may be used in the preparation of the present composition after being isolated from the reaction solution. The polymer can be isolated by known isolation methods, such as a method of pouring the reaction solution into a large amount of poor solvent and drying the resulting precipitate under reduced pressure, or a method of distilling the reaction solution under reduced pressure using an evaporator.

The weight average molecular weight (Mw) of the polymer [A] in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 3,000 or more. Mw of 3,000 or more is preferable in that a cured product having sufficiently high heat resistance, bending resistance, and chemical resistance and good developability can be obtained. The Mw of the polymer [A] is more preferably 5,000 or more, and even more preferably 6,000 or more. In addition, from the viewpoint of improving film-forming properties, the Mw of the polymer [A] is preferably 150,000 or less, more preferably 100,000 or less, and even more preferably 80,000 or less.

[A] For the polymer, the molecular weight distribution (Mw/Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less.

<[B] Photosensitive compound>
The photosensitive compound may be any component that changes the solubility of the composition by irradiation with radiation, and examples of such compounds include quinone diazide compounds, photoacid generators, and photopolymerization initiators. Among these, quinone diazide compounds and photoacid generators are preferably used. Here, in this specification, a "quinone diazide compound" is a substance that changes to an indene carboxylic acid by irradiation with radiation, and a "photoacid generator" is a substance that generates an acid by irradiation with radiation and eliminates an acid-dissociable group possessed by a component in the composition.

(Quinone diazide compounds)
The quinone diazide compound may be a condensate of a phenolic compound or an alcoholic compound (hereinafter also referred to as "mother nucleus") with an orthonaphthoquinone diazide compound. Of these, the quinone diazide compound used is preferably a condensate of a compound having a phenolic hydroxyl group as the mother nucleus with an orthonaphthoquinone diazide compound. Specific examples of the mother nucleus include the compounds described in paragraphs 0065 to 0070 of JP-A-2014-186300. The orthonaphthoquinone diazide compound is preferably 1,2-naphthoquinone diazide sulfonic acid halide.

As the quinone diazide compound, a condensation product of a phenolic compound or alcoholic compound as the mother nucleus and 1,2-naphthoquinone diazide sulfonic acid halide can be preferably used, and a condensation product of a phenolic compound and 1,2-naphthoquinone diazide sulfonic acid halide can be more preferably used.

Specific examples of quinone diazide compounds include 4,4'-dihydroxydiphenylmethane, 2,3,4,2',4'-pentahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, tri(p-hydroxyphenyl)methane, 1,1,1-tri(p-hydroxyphenyl)methane, 1,1,1-tri(p-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,3-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene, 1, Examples include ester compounds of a phenolic hydroxyl group-containing compound selected from 4-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene, 4,6-bis[1-(4-hydroxyphenyl)-1-methylethyl]-1,3-dihydroxybenzene, and 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol with 1,2-naphthoquinone diazide-4-sulfonic acid chloride or 1,2-naphthoquinone diazide-5-sulfonic acid chloride.

In the condensation reaction to obtain the above condensation product, the ratio of the mother nucleus to the 1,2-naphthoquinone diazide sulfonic acid halide is preferably such that the amount of 1,2-naphthoquinone diazide sulfonic acid halide used is an amount equivalent to 30 to 85 mol %, and more preferably an amount equivalent to 50 to 70 mol %, of the number of OH groups in the mother nucleus. The above condensation reaction can be carried out according to a known method.

When a quinone diazide compound is used as the photosensitive compound, the content of the quinone diazide compound in the composition is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the polymer [A] contained in the composition. The content of the quinone diazide compound is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the polymer [A] contained in the composition.

When the content of the quinone diazide compound is 2 parts by mass or more, sufficient acid is generated by irradiation with actinic rays, and the difference in solubility in the developer between exposed and unexposed areas can be sufficiently large. This allows for good patterning. In addition, the amount of acid involved in the reaction with the polymer component can be increased, and the heat resistance and bending resistance of the cured product obtained using this composition can be sufficiently ensured. On the other hand, when the content of the quinone diazide compound is 60 parts by mass or less, the amount of unreacted quinone diazide compound can be sufficiently reduced, which is preferable in that it can suppress the decrease in developability and transparency caused by remaining quinone diazide compound.

(Photoacid generator)
As the photoacid generator, a compound that responds to actinic rays having a wavelength of 300 nm or more (preferably 300 to 450 nm) and generates an acid can be preferably used. When a photoacid generator that does not directly respond to actinic rays having a wavelength of 300 nm or more is used, it may be used in combination with a sensitizer so that it responds to actinic rays having a wavelength of 300 nm or more and generates an acid.

As the photoacid generator, a compound that generates an acid with an acid dissociation constant (pKa) of 4 or less can be preferably used. The acid dissociation constant of the acid generated by the photoacid generator is more preferably 3 or less, and even more preferably 2 or less.

Specific examples of photoacid generators include oxime sulfonate compounds, onium salts (sulfonium salts, iodonium salts, quaternary ammonium salts, etc.), sulfonimide compounds, halogen-containing compounds, diazomethane compounds, sulfone compounds, sulfonic acid ester compounds, and carboxylate compounds.

Specific examples of the oxime sulfonate compounds, onium salts, sulfonimide compounds, halogen-containing compounds, diazomethane compounds, sulfone compounds, sulfonate compounds, and carboxylate compounds include the compounds described in paragraphs 0034 to 0038 of JP 2012-252343 A, the compounds described in paragraphs 0078 to 0106 of JP 2014-157252 A, and the compounds described in WO 2016/124493. Of these, at least one selected from the group consisting of oxime sulfonate compounds, onium salts, sulfonimide compounds, halogen-containing compounds, sulfone compounds, and sulfonate compounds can be preferably used as the photoacid generator.

Specific examples of these compounds include oxime sulfonate compounds such as (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (5-octylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (camphorsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, (5-p-toluenesulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile, {2-[2-(4-methylphenylsulfonyloxyimino)]-2,3-dihydrothiophen-3-ylidene}-2-(2-methylphenyl)acetonitrile), 2-(octylsulfonyloxyimino)-2-(4-methoxyphenyl)acetonitrile, and the compounds described in WO 2016/124493. Commercially available oxime sulfonate compounds include Irgacure PAG121 manufactured by BASF.

Specific examples of sulfonimide compounds include N-(trifluoromethylsulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, N-(4-methylphenylsulfonyloxy)succinimide, N-(2-trifluoromethylphenylsulfonyloxy)succinimide, N-(4-fluorophenylsulfonyloxy)succinimide, N-(trifluoromethylsulfonyloxy)phthalimide, N-(camphorsulfonyloxy)phthalimide, N-(2-trifluoromethylphenylsulfonyloxy)phthalimide, N-(2-fluorophenylsulfonyloxy)phthalimide, N-(trifluoromethylsulfonyloxy)diphenylmaleimide, N-(camphorsulfonyloxy)diphenylmaleimide, 4-methylphenylsulfonyloxy)diphenylmaleimide, and trifluoromethanesulfonic acid-1,8-naphthalimide (naphthalimide trifluoromethanesulfonate).

Specific examples of onium salts include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalenesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfon ... Examples include phenylsulfonium 10-camphorsulfonate, triphenylsulfonium hexafluoroantimonate, 2-oxocyclohexyldicyclohexylsulfonium trifluoromethanesulfonate, 1-naphthyldiethylsulfonium trifluoromethanesulfonate, 1-(4-benzyloxy)tetrahydrothiophenium trifluoromethanesulfonate, 1-(naphthylacetomethyl)tetrahydrothiophenium trifluoromethanesulfonate, and 4,7-di-n-butoxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate.

Specific examples of halogen-containing compounds include phenylbis(trichloromethyl)-s-triazine, 4-methoxyphenylbis(trichloromethyl)-s-triazine, and 1-naphthylbis(trichloromethyl)-s-triazine. Specific examples of sulfone compounds include 4-trisphenacylsulfone, mesitylphenacylsulfone, and bis(phenylsulfonyl)methane. Examples of sulfonic acid ester compounds include benzoin tosylate, pyrogallol tris(trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo[2,2,1]hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide trifluoromethanesulfonate, and 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate.

When a photoacid generator is used as the photosensitive compound, the content of the photoacid generator in the composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the polymer [A] contained in the composition. The content of the photoacid generator is preferably 35 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the polymer [A] contained in the composition. When the content of the photoacid generator is 0.5 parts by mass or more, sufficient acid is generated in the exposed part by irradiation with radiation, and the difference in solubility between the exposed part and the unexposed part in the alkaline solution can be sufficiently increased. This allows good patterning to be performed. In addition, the amount of acid involved in the reaction with the polymer [A] can be increased, and the heat resistance and bending resistance of the obtained cured product can be sufficiently ensured. On the other hand, by setting the content of the photoacid generator to 35 parts by mass or less, the amount of unreacted photoacid generator after exposure can be sufficiently reduced, and the decrease in developability due to the remaining photoacid generator can be suppressed.

<Other ingredients>
The composition may further contain components other than the polymer [A] and the photosensitive compound [B] (hereinafter also referred to as "other components"). Examples of the other components include a compound [C] having two or more crosslinkable functional groups (excluding the polymer [A]; hereinafter also simply referred to as "compound [C]"), an adhesion aid [D], a surfactant [E], and a solvent [F].

([C] Compound)
The compound [C] is a component that forms a crosslinked structure between or within the molecules of the polymer [A] by light or heat, or forms a bond between the compounds [C] themselves. It is preferable that the polymer [A] contains the structural unit (A2) together with the structural unit (A1) in the present composition, or that the curable composition contains the polymer [A] and the compound [C], in that the heat resistance and bending resistance of the cured product obtained by using the present composition can be further improved.

Examples of the crosslinkable functional group possessed by the compound [C] include a cyclic ether group, a cyclic thioether group, a carboxy group, a cyclic carbonate group, an alcoholic hydroxyl group, an amino group, a protected amino group, a protected isocyanate group, a polymerizable unsaturated bond group, a hydroxyalkylamide group, an oxazoline group, and an alkoxymethylphenyl group. The crosslinkable functional group reacts with the polymer [A] to form a crosslinked structure between or within the molecules of the polymer [A], and from the viewpoint of making the heat resistance and bending resistance of the cured product excellent, at least one type selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group is preferable, and at least one type selected from the group consisting of an oxiranyl group, an oxetanyl group, a hydroxyalkylamide group, a hydroxymethylphenyl group, and an alkoxymethylphenyl group is more preferable.

The number of crosslinkable functional groups that the compound [C] has in one molecule is preferably 2 to 10, and more preferably 3 to 8, from the viewpoint of sufficiently improving the heat resistance and bending resistance of the cured product and suppressing film shrinkage.

Specific examples of the compound [C] include compounds having an epoxy group, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, triglycidyl isocyanurate, glycerol polyglycidyl ether, pentaerythritol tetraglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, N,N',N',N''-tetraglycidyl glycoluril, 1,6-hexanediol diglycidyl ether, trimethyl arylpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, N,N-diglycidyl-cyclohexylamine, epoxidation reaction product of 2,2'-diallyl bisphenol A diallyl ether with hydrogen peroxide, etc.;
As a compound having a cyclocarbonate group, a compound in which the epoxy group of the above-exemplified compound having an epoxy group is protected (for example, N,N,N',N'-tetra[(2-oxo-1,3-dioxolan-4-yl)ethyl]-4,4'-diaminodiphenylmethane);
As the compound having a thiirane group, the above-exemplified compounds in which the epoxy group is replaced with a thiirane group are included;
Examples of the compound having a hydroxyalkylamide group include compounds represented by the following formulas (c-1) to (c-7):
Examples of compounds having one or both of a hydroxymethylphenyl group and an alkoxymethylphenyl group include 2,2-bis(4-hydroxymethylphenyl)propane, 2,2-bis(2,3,4-trihydroxymethylphenyl)propane, and compounds represented by the following formulas (c-8) to (c-16):
Examples of compounds having a protected isocyanate group include compounds in which the isocyanate group in tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, or diphenylmethane diisocyanate is protected.

When the composition contains the [C] compound, the content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the [A] polymer contained in the composition. The content of the [C] compound is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the [A] polymer contained in the composition.

([D] Adhesion Aid)
The adhesion aid is a component that improves the adhesion between the cured product formed by using the composition and the substrate. As the adhesion aid, a functional silane coupling agent having a reactive functional group can be preferably used. Examples of the reactive functional group of the functional silane coupling agent include a carboxy group, a (meth)acryloyl group, an epoxy group, a vinyl group, and an isocyanate group.

Specific examples of functional coupling agents include trimethoxysilylbenzoic acid, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

If the composition contains an adhesion aid, the content is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer [A] contained in the composition.

([E] Surfactant)
The surfactant can be used to improve the coating properties of the composition (wetting and spreading properties and reducing coating unevenness). Examples of the surfactant include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. The surfactant can be selected from known ones such as these commercially available products.

When a surfactant is blended in the composition, the content of the surfactant is preferably 0.01 to 1.5 parts by mass, more preferably 0.02 to 1.2 parts by mass, and even more preferably 0.05 to 1.0 parts by mass, per 100 parts by mass of the polymer [A] contained in the composition.

([F] Solvent)
The present composition is preferably a liquid composition in which the polymer [A], the photosensitive compound [B], and components to be blended as necessary are dissolved or dispersed in a solvent. The solvent to be used is preferably an organic solvent that dissolves each component to be blended in the present composition and does not react with each component.

Specific examples of solvents include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, and ethyl 3-ethoxypropionate; ethers such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, ethylene diglycol monomethyl ether, ethylene diglycol ethyl methyl ether, dimethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and diethylene glycol ethyl methyl ether; amides such as dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

Among these, the solvent preferably contains at least one selected from the group consisting of ethers and esters, and more preferably contains at least one selected from the group consisting of ethylene glycol alkyl ether acetate, diethylene glycols, propylene glycol monoalkyl ether, and propylene glycol monoalkyl ether acetate.

The content of the solvent in the composition (the total amount when two or more types of solvents are included) is preferably 50 to 95 parts by mass, and more preferably 60 to 90 parts by mass, per 100 parts by mass of all components of the composition.

Other components may include, in addition to those mentioned above, known additives such as acid diffusion control agents, sensitizers, antioxidants, thermal radical generators, thermal acid generators, ultraviolet absorbers, thickeners, development accelerators, acid multipliers, plasticizers, suspending agents, polymerization inhibitors, and chain transfer agents. The blending ratio of these components is appropriately selected according to each component within a range that does not impair the effects of the present disclosure.

The solids concentration of the present composition (the ratio of the total mass of the components other than the solvent in the curable composition to the total mass of the curable composition) is appropriately selected taking into consideration the viscosity, volatility, etc. The solids concentration of the present composition is preferably in the range of 5 to 60 mass%. If the solids concentration is 5 mass% or more, a sufficient thickness of the coating film can be ensured when the present composition is applied to a substrate. If the solids concentration is 60 mass% or less, the thickness of the coating film does not become too large, and the viscosity of the present composition can be appropriately increased, ensuring good coatability. The solids concentration of the present composition is more preferably 10 to 55 mass%, and even more preferably 12 to 50 mass%.

<Cured material for organic EL device and method for producing same>
The cured product of the present disclosure is formed by the present composition prepared as described above. With this composition, a pattern film can be formed that has high radiation sensitivity, high transmittance, low dielectric constant, and excellent heat resistance, low water permeability, and bending resistance. Such a present composition can be preferably used as a composition for forming a cured product of an organic EL element, and particularly, can be preferably used as a composition for forming a planarizing film, a partition wall, or an interlayer insulating film in an organic EL element.

When producing a cured product from the present composition, either positive development, which removes the irradiated portion, or negative development, which removes the non-irradiated portion, may be used. The present composition is particularly preferably used for forming a positive cured product. The cured product of the present disclosure can be produced using the present composition by a method including, for example, the following steps 1 to 4.
(Step 1) A step of forming a coating film using the present composition.
(Step 2) A step of irradiating at least a portion of the coating film with radiation.
(Step 3) A step of developing the coating film after irradiation.
(Step 4) A step of heating the developed coating film.
Each step will be described in detail below.

[Step 1: Coating film formation step]
In step 1, the composition is applied to a substrate. Examples of the substrate include glass substrates, silicon substrates, and resin substrates. The surface of the substrate on which the coating film is formed may have a thin metal film formed thereon according to the application, or may have been subjected to various surface treatments such as HMDS (hexamethyldisilazane) treatment.

　Examples of methods for applying the composition include spraying, roll coating, spin coating, slit die coating, bar coating, and inkjet coating. Among these, spin coating, slit die coating, and bar coating are preferred.

In step 1, the composition applied to the substrate is preferably subjected to a heat treatment (pre-baking) to remove the solvent in the composition and form a coating film on the substrate. Pre-baking conditions vary depending on the type and content ratio of each component in the composition, but are, for example, 60 to 130°C for 0.5 to 10 minutes. The thickness of the coating film formed (i.e., the film thickness after pre-baking) is preferably 0.1 to 12 μm. The composition applied to the substrate may be subjected to reduced pressure drying (VCD) before pre-baking.

[Step 2: Irradiation step]
In step 2, at least a part of the coating film made of the present composition formed in step 1 is irradiated with radiation. In this case, by irradiating the coating film with radiation through a mask having a predetermined pattern, a cured product having a pattern can be formed. Examples of radiation include charged particle beams such as ultraviolet rays, far ultraviolet rays, visible rays, X-rays, and electron beams. Among these, ultraviolet rays are preferred, and examples thereof include g-rays (wavelength 436 nm) and i-rays (wavelength 365 nm). The exposure dose of radiation is preferably 0.1 to 20,000 J/ ^m2 .

[Step 3: Development step]
In step 3, the coating film irradiated in step 2 is developed. The developer may be an aqueous solution of an alkali (basic compound). Examples of the alkali include sodium hydroxide, tetramethylammonium hydroxide, and the alkalis exemplified in paragraph [0127] of JP2016-145913A. The alkali concentration in the aqueous alkali solution is preferably 0.1 to 5% by mass from the viewpoint of obtaining suitable developability.

The development method may be a suitable method such as a puddle method, a dipping method, a rocking immersion method, or a shower method. The development time varies depending on the composition of the composition, but is, for example, 30 to 120 seconds. After the development step, it is preferable to perform a rinse process by washing the patterned coating film with running water.

[Step 4: Heat curing step]
In step 4, the coating film developed in step 3 is heated (post-baked). Post-baking can be performed using a heating device such as an oven or a hot plate. Regarding post-baking conditions, the heating temperature is, for example, 120 to 260° C. The heating time is, for example, 5 to 40 minutes when the heating treatment is performed on a hot plate, and 10 to 80 minutes when the heating treatment is performed in an oven. This heating treatment causes a curing reaction to proceed, and a cured product having a desired pattern can be formed on a substrate. The shape of the pattern of the cured product is not particularly limited, and examples thereof include a line and space pattern, a dot pattern, a hole pattern, and a lattice pattern.

The cured product obtained from this composition can also be used as a dry etching resist. When using the cured product as a dry etching resist, dry etching processes such as ashing, plasma etching, and ozone etching can be used as the etching process.

<Organic EL element>
The organic EL element of the present disclosure includes a cured product formed using the present composition. The type of the cured product is not particularly limited, but examples thereof include a planarizing film, a partition wall, or an interlayer insulating film that is included in an organic EL element. The present composition is particularly suitable as a planarizing film-forming composition for an organic EL element, that is, a planarizing film-forming composition for forming a planarizing film that is an insulating layer that covers steps of TFT circuits and wirings formed on a substrate, since the present composition can provide a cured product that exhibits excellent bending resistance.

The cured product formed using this composition is poorly permeable and has excellent bending resistance, and is therefore suitable for use as an organic EL element for flexible displays. Examples of flexible displays include foldable displays that can be folded, bendable displays that can be folded back or bent, and rollable displays that can be rolled up. The cured product formed using this composition is particularly suitable as a cured product to be provided in an organic EL element for a bendable display, and is particularly suitable as a planarizing film for a bendable organic EL display.

According to the present disclosure described above in detail, the following means are provided.
[Means 1] A curable composition for an organic EL device comprising: [A] a polymer including a structural unit derived from a compound having an acidic group; and [B] a photosensitive compound, wherein the polymer [A] includes a structural unit (I) derived from an aromatic vinyl compound and a structural unit (II) derived from a maleimide compound, and the compound having an acidic group includes at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and the total proportion of the structural unit (I) and the structural unit (II) in the polymer [A] is 70 mol % or more based on all structural units of the polymer [A].
[Means 2] The curable composition for an organic EL device according to [Means 1], wherein a molar ratio of the structural unit (I) to the structural unit (II) in the polymer [A] is structural unit (I)/structural unit (II)=60/40 to 40/60.
[Means 3] The curable composition for an organic EL device according to [Means 1] or [Means 2], wherein the polymer [A] has a crosslinkable functional group.
[Means 4] The curable composition for an organic EL device according to [Means 3], wherein the crosslinkable functional group is at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group.
[Means 5] The curable composition for an organic EL device according to [Means 3] or [Means 4], wherein the polymer [A] is at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and further contains a structural unit derived from a compound having a crosslinkable functional group.
[Means 6] The curable composition for an organic EL device according to any one of [Means 1] to [Means 5], further comprising [C] a compound having two or more crosslinkable functional groups (excluding the polymer [A]).
[Means 7] The curable composition for an organic EL device according to [Means 6], wherein the compound [C] has two or more of at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group.
[Means 8] The curable composition for an organic EL device according to any one of [Means 1] to [Means 7], wherein the photosensitive compound [B] is a quinone diazide compound.
[0023] [Measures 9] The curable composition for an organic EL device according to any one of [Measures 1] to [Measures 7], wherein the photosensitive compound [B] is a photoacid generator.
[Means 10] The curable composition for organic EL devices according to any one ^of [Means ¹ ] to [Means ⁹ ], wherein the compound having an acidic group is at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C(R ¹ )(R ² )-OH" (wherein R 1 and R 2 are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms, and "* 1 " represents a bond to an aromatic ring), and maleimide.
[Means 11] A method for producing a cured product for an organic EL device, comprising: forming a coating film using the curable composition according to any one of [Means 1] to [Means 10]; irradiating at least a part of the coating film with radiation; developing the coating film after irradiation with radiation; and heating the developed coating film.
[Means 12] A cured product for an organic EL device formed using the curable composition according to any one of [Means 1] to [Means 10].
[Means 13] The cured product for an organic EL device according to [Means 12], which is a planarizing film, a partition wall, or an interlayer insulating film.
[Means 14] An organic EL device comprising the cured product according to [Means 12].
[Means 15] A polymer comprising a structural unit derived from an aromatic vinyl compound and a structural unit derived from a maleimide compound, wherein the total ratio of the structural units derived from the aromatic vinyl compound and the structural units derived from the maleimide compound is 70 mol % or more based on all structural units of the polymer, the polymer comprises a structural unit derived from a compound having an acidic group and a structural unit derived from a compound having a crosslinkable functional group, and the compound having the acidic group and the compound having the crosslinkable functional group are at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and the compound having the acidic group is at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C( ^R1 )( ^R2 )-OH" (wherein ^R1 and ^R2 are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms, and "* ¹ " represents a bond to an aromatic ring), and a maleimide.

The polymer of [Means 15] above is suitable as a polymer component of a curable composition for forming a cured product for an organic EL device (preferably a planarizing film, an interlayer insulating film, or a partition wall). That is, the polymer of [Means 15] above is a suitable embodiment of the polymer [A] contained in the curable composition for an organic EL device of the present disclosure. The specific configuration and manufacturing method of the polymer are as described above.

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to these examples. Note that "parts" and "%" in the examples and comparative examples are by mass unless otherwise specified.

[Weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn)]
The Mw and Mn of the polymers synthesized in the following Synthesis Examples were measured by gel permeation chromatography (GPC) using the following apparatus and conditions. The molecular weight distribution (Mw/Mn) was calculated from the measured Mw and Mn.
Apparatus: GPC-101 manufactured by Showa Denko Co., Ltd.
GPC column: Shimadzu GLC's GPC-KF-801, GPC-KF-802, GPC-KF-803, and GPC-KF-804 combined Mobile phase: Tetrahydrofuran (in the case of styrene-maleimide resin), or N,N-dimethylformamide solution containing lithium bromide and phosphoric acid (in the case of polyimide)
Column temperature: 40°C
Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
・Detector: Differential refractometer ・Standard material: Monodisperse polystyrene

[Monomer]
The abbreviations of the monomers used in the synthesis of the polymer are as follows.
<<Monomer having an acidic group (aromatic vinyl compound, maleimide compound): M1>>
MI-1 to MI-3, OL-1 to OL-3: Compounds represented by the following formulae (MI-1) to (MI-3) and (OL-1) to (OL-3), respectively.

<<Monomer having a crosslinkable functional group (aromatic vinyl compound, maleimide compound): M2>>
MI-4, OL-4 to OL-7: Compounds represented by the following formulas (MI-4), (OL-4) to (OL-7), respectively.

<<Monomer having an acid-dissociable group (aromatic vinyl compound, maleimide compound): M3>>
MI-5, MI-6, OL-8: Compounds represented by the following formulae (MI-5), (MI-6), and (OL-8), respectively.

Other Monomers
MMA: methyl methacrylate MAA: methacrylic acid GMA: glycidyl methacrylate MI-7 to MI-10, OL-9 to OL-13: compounds represented by the following formulas (MI-7) to (MI-10), (OL-9) to (OL-13), respectively.

1. Polymer synthesis [Synthesis Example 1] Synthesis of polymer P-1 (styrene-maleimide resin) In a 100 mL two-neck flask, 50 mol parts of maleimide and 50 mol parts of styrene as polymerization monomers, 5 mass parts of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator, and N-methyl-2-pyrrolidone (NMP) as a solvent were added under nitrogen to a concentration of 20 mass%, and polymerization was carried out at 70°C for 6 hours. After polymerization, the solid matter obtained by reprecipitation in an aqueous methanol solution was filtered and vacuum dried at room temperature for 8 hours to obtain polymer P-1 (styrene-maleimide resin). The Mw of the obtained polymer P-1 was 41,300, and the molecular weight distribution (Mw/Mn) was 2.52.

[Synthesis Examples 2 to 18, 20, 21] Synthesis of polymers P-2 to P-18, 20, 21 (styrene-maleimide resins) Polymerization was carried out in the same manner as in Synthesis Example 1, except that the type and amount of monomers used in polymerization were changed as shown in Table 1, to obtain polymers P-2 to P-18, 20, 21. In Table 1, the numbers in parentheses indicate the amount (unit: mol%) of each monomer relative to the total amount of monomers used in each polymerization. The numbers in the "Total amount T (S/M)" column indicate the total amount (unit: mol%) of aromatic vinyl compounds and maleimide compounds out of all monomers used in the synthesis of the polymers.

Synthesis Example 19 Synthesis of Polymer P-19 (Polyimide) 100 parts by mole of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane was dissolved in N-methyl-2-pyrrolidone (NMP), and 100 parts by mole of 4,4′-oxydiphthalic anhydride was added thereto and reacted at 40° C. for 8 hours to obtain a polyamic acid solution containing 20% by mass of polyamic acid.
Next, NMP was added to the obtained polyamic acid solution to make the concentration of polyamic acid 10% by mass, and pyridine and acetic anhydride were added thereto, and a dehydration ring-closing reaction was carried out at 90° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a polyimide solution containing 15% by mass of polyimide with an imidization rate of about 70%. The obtained polyimide solution was added to methanol, and the precipitated solid was washed with an aqueous methanol solution. The obtained solid was dried to obtain polymer P-19 (polyimide). The Mw of the obtained polymer P-19 was 32,000, and the molecular weight distribution (Mw/Mn) was 2.21.

2. Preparation and evaluation of curable compositions [Example 1]
(1) Preparation of Curable Composition R-1 100 parts by mass of polymer P-1 as a resin, 20 parts by mass of a quinone diazide compound (condensate of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol (1.0 mol) and 1,2-naphthoquinone diazide-5-sulfonic acid chloride (2.0 mol)) as a photosensitive compound, 5 parts by mass of an adhesion assistant (γ-glycidoxypropyltrimethoxysilane), and 0.5 parts by mass of a surfactant ("FTX-218", manufactured by NEOS Corporation) were mixed. Further, a mixed solution of gamma-butyrolactone and diethylene glycol ethyl methyl ether (gamma-butyrolactone:diethylene glycol ethyl methyl ether=50:50 (mass ratio)) was added as a solvent so that the solid content concentration was 20 mass%, and then the mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a curable composition R-1.

(2) Evaluation of Sensitivity (Radiation Sensitivity) Using a spinner, the curable composition R-1 was applied onto a silicon substrate that had been subjected to HMDS treatment at 60° C. for 60 seconds, and then prebaked on a hot plate at 90° C. for 2 minutes to form a coating film having a thickness of 3.0 μm. This coating film was irradiated with a predetermined amount of ultraviolet light through a pattern mask having a line-and-space pattern with a width of 10 μm, using a Canon Inc. "MPA-600FA" exposure machine. Next, development treatment was performed at 25° C. for 60 seconds using a developer (a 2.38% by mass aqueous solution of tetramethylammonium hydroxide), and then washed with running ultrapure water for 1 minute. The minimum exposure dose capable of forming a 10 μm wide line and space pattern was measured, and the measured value was rated as "excellent (◎)" when it was less than 1000 J/m ² , "good (○)" when it was 1000 J/m ² or more and less than 2000 J/m ² , "fair (△)" when a 10 μm wide line and space pattern was obtained but the minimum exposure dose was 2000 J/m ² or more, and "not good (×)" when a 10 μm wide line and space pattern was not obtained. The sensitivity was evaluated as "good (○)" in this example.

(3) Evaluation of transmittance (light transmittance) Using a spinner, the curable composition R-1 was applied onto a glass substrate, and then prebaked on a hot plate at 90 ° C. for 2 minutes to form a coating film with a thickness of 3.0 μm. Next, using a proximity exposure machine (Canon's "MA-1200" (ghi line mixed)), 3000 J / m ² of light was irradiated onto the entire substrate, and then the glass substrate was heated at 250 ° C. for 60 minutes in a clean oven substituted with nitrogen to form a cured film. The transmittance of the formed cured film was measured with an ultraviolet-visible spectrophotometer (JASCO Corporation's "V-630"). The transmittance of light with a wavelength of 380 nm was evaluated as "good (○)" when it was 70% or more, "acceptable (△)" when it was 50% or more and less than 70%, and "not acceptable (×)" when it was less than 50%. As a result, in this example, it was evaluated as "good (○)".

(4) Evaluation of heat resistance Using a spinner, the curable composition R-1 was applied onto a silicon substrate, and then prebaked on a hot plate at 90 ° C. for 2 minutes to form a coating film with a thickness of 3.0 μm. Next, a proximity exposure machine (Canon's "MA-1200" (ghi line mixed)) was used to irradiate the entire substrate with 3000 J / m ² light, and then the silicon substrate was heated at 250 ° C. for 60 minutes in a clean oven substituted with nitrogen to form a cured film. The 1% thermal weight loss temperature of the formed cured film was measured under air using a differential thermal / thermogravimetric simultaneous measurement device (Hitachi High-Tech Science's "TG / DTA220U"). The heat resistance was evaluated as "good (○)" when the 1% weight loss temperature was 300 ° C. or more, "acceptable (△)" when the temperature was 250 ° C. or more and less than 300 ° C., and "not acceptable (×)" when the temperature was less than 250 ° C. As a result, in this example, it was rated as "good (○)".

(5) Evaluation of dielectric constant (measurement of relative dielectric constant)
After applying the curable composition R-1 onto a SUS304 substrate whose surface had been smoothed by polishing with a sisal buff (hemp buff), the solvent was removed from the curable composition R-1 on the substrate under vacuum with an ultimate pressure set to 100 Pa, and the substrate was prebaked at 90°C for 2 minutes to form a coating film having an average thickness of 3.0 μm. Next, a proximity exposure machine (Canon's "MA-1200" (ghi line mixture)) was used to irradiate the entire surface of the substrate with light of 3000 J/ ^m2 , and then the substrate was heated at 250°C for 60 minutes in a nitrogen-substituted clean oven to form a cured film (insulating film) on the substrate. A Pt/Pd electrode pattern was formed on the insulating film by vapor deposition to prepare a sample for measuring dielectric constant.
Using the prepared dielectric constant measurement sample, the dielectric constant was measured by the CV method at a frequency of 10 kHz using an LCR meter (HP16451B electrode and HP4284A precision LCR meter manufactured by Hewlett-Packard Japan, LLC). The dielectric constant was evaluated as follows: when the dielectric constant was 3.0 or less, it was rated as "excellent (◎)", when it was more than 3.0 and less than 3.2, it was rated as "good (○)", when it was more than 3.2 and less than 3.5, it was rated as "passable (△)", and when it was more than 3.5, it was rated as "unacceptable (×)". As a result, in this example, the dielectric constant was rated as "excellent (◎)".

(6) Evaluation of Water Permeability The curable composition R-1 was applied to a polyimide sheet having a thickness of 25 μm by spin coating to a film thickness of 10 μm, and prebaked at 80 ° C. for 1.5 minutes. Next, using a proximity exposure machine (Canon's "MA-1200" (ghi line mixture)), the entire surface of the substrate was irradiated with light of 3000 J / m ² , and then heated at 250 ° C. for 60 minutes to form a cured film on the polyimide sheet. The laminated film of this polyimide sheet and the cured film was placed in the opening of an aluminum cup containing 15 g of distilled water with the surface of the cured film facing inward, and the opening of the aluminum cup was covered so as to be sealed with the laminated film. This was placed in a thermostatic chamber at 50 ° C., and the weight loss of the cup after 150 hours was measured, and the water permeability per unit area was calculated. The permeability was evaluated as follows: if the weight loss value was 500 g/ ^cm2 or less, it was rated as "good (○)", if it was more than 500 g/ ^cm2 and less than 700 g/ ^cm2 , it was rated as "passable (△)", and if it was more than 700 g/ ^cm2 , it was rated as "not good (×)". When this value is 500 g/ ^cm2 or less, the permeability is sufficiently low. As a result, this example was rated as "good (○)".

(7) Evaluation of bending resistance (bending resistance) After applying the curable composition R-1 onto a polyimide film substrate using a spin coater, the ultimate pressure was set to 100 Pa from the curable composition R-1 on the substrate, and the solvent was removed under vacuum, and the substrate was prebaked at 90 ° C. for 2 minutes to form a coating film with an average film thickness of 3.0 μm. Next, a developer (a 2.38% by mass aqueous solution of tetramethylammonium hydroxide) was used to perform a development process at 25 ° C. for 60 seconds, and then the substrate was washed with running ultrapure water for 1 minute. The obtained coating film was irradiated with 3000 J / m ² light on the entire substrate using a proximity exposure machine (Canon's "MA-1200" (ghi line mixing)), and then heated at 250 ° C. for 1 hour in a nitrogen-substituted clean oven to form a cured film on the substrate.
The obtained substrate with the cured film was cut into a size of 50 mm long x 50 mm wide. Next, the substrate with the cured film was folded so that the surface on which the cured film was formed was inward and the cured film was in contact with each other, and the substrate was kept in this state for 10 minutes. After 10 minutes from folding, the folded substrate with the cured film was opened, and the folded part of the surface of the cured film was observed using an optical microscope, and the bending resistance (bending resistance) was evaluated based on the change in appearance. The evaluation criteria were as follows: when there were no cracks in the cured film, it was rated as "good (○)", when there were cracks in a part of the cured film, it was rated as "passable (△)", and when there were cracks in the entire cured film, it was rated as "unacceptable (×)". As a result, in this example, it was rated as "passable (△)".

(8) Element Evaluation <Fabrication of Organic EL Element Substrate>
Using a spinner, the prepared composition was applied onto a glass substrate (manufactured by Nippon Electric Glass Co., Ltd., "OA-10") on which an ITO transparent electrode was formed in an array, and then prebaked on a hot plate at 90°C for 2 minutes to form a coating film with a thickness of 3.0 μm. This coating film was irradiated with a predetermined amount of ultraviolet light through a pattern mask having a 10 μm contact hole pattern using a Canon Inc. "MPA-600FA" exposure machine. Next, a development process was performed at 25°C for 60 seconds using a developer (a 2.38% by mass aqueous solution of tetramethylammonium hydroxide), and then washed with running ultrapure water for 1 minute. At this time, the minimum exposure dose capable of forming a 10 μm contact hole pattern was measured. Next, using a proximity exposure machine (Canon's "MA-1200" (mixed ghi line)), the entire surface of the substrate was irradiated with light of 3000 J/ ^m2 , and then heated at 250°C for 1 hour in a nitrogen-substituted clean oven to form a cured film (also referred to as a "patterned cured resin layer") having contact holes on the glass substrate.
For a glass substrate having a patterned cured resin layer, an Al film having a thickness of 100 nm was formed on the patterned cured resin layer by DC sputtering using an Al target through a metal mask having a predetermined pattern. An ITO film having a thickness of 20 nm was formed on the Al film by RF sputtering using an ITO target. In this way, an anode layer consisting of an Al film and an ITO film was formed.
A coating film was formed on the anode layer using a resist material ("OPTOMER NN803" manufactured by JSR Corporation), and a series of treatments including i-line (wavelength 365 nm) irradiation, development, washing with running water, air drying, and heat treatment were performed to form a pixel-defining layer having a part of the anode layer as an opening region.
The substrate on which the anode and the pixel defining layer were formed was moved to a vacuum deposition chamber, and the deposition chamber was evacuated to 1E-4 Pa. After that, molybdenum oxide (MoOx) having hole injection properties was deposited on the substrate by a resistance heating deposition method using a deposition mask having a predetermined pattern under conditions of a deposition rate of 0.004 to 0.005 nm/sec, thereby forming a hole injection layer with a thickness of 1 nm.
On the hole injection layer, a film of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD) having hole transport properties was formed by resistance heating deposition under the same exhaust conditions as those for the hole injection layer, using a deposition mask with a predetermined pattern, to form a hole transport layer with a thickness of 35 nm. The film formation rate was 0.2 to 0.3 nm/sec.
On the hole transport layer, an alkylate complex of tris(8-quinolinolato)aluminum was deposited as a green light emitting material by resistance heating deposition under the same deposition conditions as those for the hole transport layer, using a deposition mask with a predetermined pattern, to form a light emitting layer with a thickness of 35 nm. The deposition rate was 0.5 nm/sec or less.
On the light-emitting layer, lithium fluoride was deposited by resistance heating deposition under the same exhaust conditions as those for the hole injection layer, using a deposition mask with a predetermined pattern, to form a film of 0.8 nm in thickness at a deposition rate of 0.004 nm/sec or less.
Next, Mg and Ag were simultaneously deposited on the electron injection layer by resistance heating deposition under the same exhaust conditions as those for the hole injection layer, using a deposition mask with a predetermined pattern, to form a first cathode layer with a thickness of 5 nm. The deposition rate was 0.5 nm/sec or less.
Next, the substrate was transferred to another film formation chamber (sputtering chamber), and a second cathode layer having a thickness of 100 nm was formed on the first cathode layer by RF sputtering using a mask having a predetermined pattern and an ITO target.
In this manner, an organic EL element was formed on the substrate, and an organic EL element substrate was obtained.

<Thin film encapsulation of organic EL elements>
On the organic EL element obtained above, a thin film sealing layer was formed by the following procedure.
The organic EL element substrate was transferred to a film-forming chamber (sputtering chamber), and an inorganic sealing layer (SiNx film) having a thickness of 100 nm was formed on the cathode layer by RF sputtering using a SiNx target using a mask having a predetermined pattern. The organic EL element substrate was then transferred to a glove box substituted with _N2 , and a curable composition containing an epoxy compound, an oxetane compound, and a polymerization initiator was discharged in a predetermined pattern by a piezoelectric inkjet printer. Then, an exposure dose of 1000 mJ/ ^cm2 was applied using a UniJetE110ZHD 395 nm LED lamp manufactured by Ushio Inc., and the formed curable composition was cured to form an organic sealing layer having a thickness of 10 μm. The organic EL element substrate was transferred to a film-forming chamber (sputtering chamber), and an inorganic sealing layer (SiNx film) having a thickness of 100 nm was formed on the organic sealing layer by RF sputtering using a mask having a predetermined pattern using a SiNx target. In this manner, an organic EL element substrate with a sealing layer was obtained.

<Reliability evaluation of organic EL elements>
The obtained organic EL element substrate with the patterned cured resin layer was subjected to reliability evaluation by the following procedure. The organic EL element substrate with the patterned cured resin layer was stored in an oven set at 60°C and humidity of 90% for 300 hours, and then a current was passed between the anode layer and the cathode layer of the organic EL element at a density of 20 mA/ ^cm2 from a constant current source via an organic EL lighting jig to light the organic EL element. Next, the luminance of the organic EL element in the front direction was measured by a luminance meter.
The lighting of the organic EL element and the measurement of the front brightness by a luminance meter were performed on the organic EL element substrate with the patterned cured resin layer and the reference organic EL element substrate without the patterned cured resin layer. The less impurities generated from the patterned cured resin layer and the less moisture that permeated the patterned cured resin layer and the less the impact of the impurities and moisture on the organic EL element, the closer the front brightness of the organic EL element substrate with the sealing layer is to the front brightness of the reference organic EL element substrate. The reliability of the organic EL element was evaluated as "good (○)" when the organic EL element substrate with the sealing layer was lit with a brightness of 80% or more compared to the front brightness of the reference organic EL element substrate, "passable (△)" when it was lit with a brightness of 50% or more and less than 80%, and "not good (×)" when it was not lit normally. As a result, in this example, it was evaluated as "good (○)".

[Examples 2 to 14, 18 to 21, Comparative Examples 1 to 6]
Curable compositions R-2 to R-14 and R-18 to R-27 were prepared with the same solvent composition and solid content concentration as in Example 1, except that the blending composition was changed as shown in Table 2. In addition, in Examples 2 to 14, 18 to 21 and Comparative Examples 1 to 6, the same types and blending amounts of adhesion aid and surfactant as in Example 1 were blended. In Examples 2 to 7, 11, 18 to 21 and Comparative Example 2, a crosslinking agent was blended. In addition, various evaluations were performed in the same manner as in Example 1 using each curable composition. The evaluation results are shown in Table 2. In addition, in Comparative Example 2 and Comparative Example 5, a line and space pattern with a width of 10 μm was not obtained in "(2) Evaluation of sensitivity (radiation sensitivity)", so no subsequent evaluation was performed, and therefore the evaluation items other than sensitivity are indicated as "-" in Table 2.

[Examples 15 to 17]
Curable compositions R-15 to R-17 were prepared with the same solvent composition and solid content concentration as in Example 1, except that the blending composition was changed as shown in Table 2. In addition, the same types and amounts of adhesion assistants and surfactants as in Example 1 were blended in Examples 15 to 17. A crosslinking agent was blended in Example 16. In addition, various evaluations were performed in the same manner as in Example 1 using each curable composition. However, in preparing the patterned cured resin layer of the organic EL element substrate, in Examples 15 to 17, after the development process and running water washing, the substrate was not irradiated with 3000 J/m ² light using a proximity exposure machine (Canon's "MA-1200" (ghi line mixing)) but was heated for 1 hour at 250 ° C. in a nitrogen-substituted clean oven. The evaluation results are shown in Table 2. The units of values in Table 2 are parts by mass.

In Table 2, the abbreviations of the compounds are as follows.
NQD: quinone diazide compound (condensation product of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol (1.0 mol) and 1,2-naphthoquinone diazide-5-sulfonic acid chloride (2.0 mol))
CAR: 4,7-di-n-butoxy-1-naphthyltetrahydrothiophenium trifluoromethanesulfonate Add-1 to Add-6: Compounds represented by the following formulas (Add-1) to (Add-6), respectively

As shown in Table 2, the curable compositions of Examples 1 to 21 were evaluated as "excellent", "good" or "fair" in sensitivity, transmittance, heat resistance, dielectric constant, poor water permeability, bending resistance and element reliability, and various properties were improved in a well-balanced manner. Among these, in particular, in Examples 2 to 6, 8 to 10, 12 to 16, 20 and 21 in which a crosslinkable functional group was introduced into the polymer [A] or any of Add-1 to Add-5 was blended as a crosslinking agent, the heat resistance and bending resistance were evaluated as good. In addition, by including a polymer using one or more of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C(R ¹ )(R ² )-OH" and maleimide as a monomer having an acidic group, a cured film having a lower dielectric constant could be obtained compared to the case in which a compound having a carboxy group was used (Example 8).

In contrast, Comparative Examples 1 and 4, which used polymers in which the total ratio of structural units (I) and structural units (II) was less than 70 mol %, were either "passable" or "failable" in heat resistance, dielectric constant, water impermeability, and element reliability, and were generally inferior to Examples 1 to 21. Comparative Example 3, which used polyimide as the polymer component, did not have sufficient sensitivity, transmittance, and dielectric constant, and Comparative Example 6, which used a copolymer of cycloolefin and a styrene compound, was rated "passable" in heat resistance, dielectric constant, and water impermeability, but "failable" in bending resistance and element reliability. Comparative Examples 2 and 5 were not photosensitive and could not be used as photosensitive compositions.

Claims (15)

[A] a polymer including a structural unit derived from a compound having an acidic group;
[B] a photosensitive compound,
Contains
The polymer (A) contains a structural unit (I) derived from an aromatic vinyl compound and a structural unit (II) derived from a maleimide compound,
The compound having an acidic group includes at least one selected from the group consisting of an aromatic vinyl compound and a maleimide compound,
a curable composition for an organic EL device, wherein a total ratio of the structural unit (I) and the structural unit (II) in the polymer (A) is 70 mol % or more based on all structural units of the polymer (A). The curable composition for organic EL devices according to claim 1, wherein the molar ratio of the structural unit (I) to the structural unit (II) in the polymer [A] is structural unit (I)/structural unit (II) = 60/40 to 40/60. The curable composition for organic EL devices according to claim 1, wherein the polymer [A] has a crosslinkable functional group. The curable composition for organic EL devices according to claim 3, wherein the crosslinkable functional group is at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group. The curable composition for organic EL devices according to claim 3, wherein the polymer [A] is at least one selected from the group consisting of aromatic vinyl compounds and maleimide compounds, and further contains a structural unit derived from a compound having a crosslinkable functional group. The curable composition for organic EL devices according to claim 1, further comprising [C] a compound having two or more crosslinkable functional groups (excluding the polymer [A]). The curable composition for organic EL devices according to claim 6, wherein the compound [C] has two or more of at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a thiirane group, a hydroxyalkylamide group, a hydroxymethylphenyl group, an alkoxymethylphenyl group, a cyclocarbonate group, and a protected isocyanate group. The curable composition for organic EL devices according to claim 1, wherein the photosensitive compound [B] is a quinone diazide compound. The curable composition for organic EL devices according to claim 1, wherein the photosensitive compound [B] is a photoacid generator. The curable composition for an organic EL device according to claim 1, wherein the compound having an acidic group ^is at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C(R1)( ^R2 )-OH" (wherein ^R1 and ^R2 are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms, and "* ¹ " represents a bond to an aromatic ring), and maleimide. A step of forming a coating film using the curable composition according to any one of claims 1 to 10;
exposing at least a portion of the coating to radiation;
developing the coating film after irradiation;
heating the developed coating;
The method for producing a cured material for an organic EL element comprising the steps of: A cured product for an organic EL device formed using the curable composition according to any one of claims 1 to 10. The cured material for organic EL devices according to claim 12, which is a planarizing film, a partition wall, or an interlayer insulating film. An organic EL element comprising the cured product according to claim 12. A polymer comprising a structural unit derived from an aromatic vinyl compound and a structural unit derived from a maleimide compound,
the total proportion of structural units derived from an aromatic vinyl compound and structural units derived from a maleimide compound is 70 mol % or more based on the total structural units of the polymer,
a structural unit derived from a compound having an acidic group and a structural unit derived from a compound having a crosslinkable functional group, the compound having an acidic group and the compound having a crosslinkable functional group being at least one selected from the group consisting of an aromatic vinyl compound and a maleimide compound;
The compound having an acidic group is at least one selected from the group consisting of a compound having a phenolic hydroxyl group, a compound having a group "* ¹ -C( ^R1 )( ^R2 )-OH" (wherein ^R1 and ^R2 are each independently a cyano group or a fluoroalkyl group having 1 to 3 carbon atoms, and "* ¹ " represents a bond to an aromatic ring), and a maleimide.