JP7472665B2 - Radiation-sensitive composition, insulating film for display device, display device, method for forming insulating film for display device, and polymer - Google Patents

Description

The present invention relates to a radiation-sensitive composition, an insulating film for a display device, a display device, a method for forming an insulating film for a display device, and a polymer.

One type of light-emitting element that has been developed in recent years is an organic electroluminescence (EL) element having a laminated structure including an anode layer, an organic light-emitting layer, and a cathode layer. A known display device having an organic EL element is an organic EL device with a touch panel provided on the front surface of the device (see Patent Document 1).

An organic EL device with a touch panel is manufactured, for example, by attaching a touch panel to a substrate on which an organic EL element is formed via an adhesive layer or bonding layer. A touch panel is usually manufactured by providing a touch panel component such as a sensor electrode on a touch panel support substrate.

JP 2015-161806 A

As described above, when a touch panel is attached to a substrate on which an organic EL element is formed via an adhesive layer or a bonding layer, the overall thickness of the organic EL device with a touch panel increases. In the case of a device with a large thickness, it is easy for damage or a decrease in function to occur when it is bent. In addition, thinning itself is desired for various display devices. Therefore, it is considered that the overall thickness of a display device such as an organic EL device with a touch panel can be reduced by directly providing a touch panel on a substrate on which an organic EL element is formed by a method such as lithography or etching. However, in the conventional method using a material containing a polyfunctional (meth)acrylate or the like as a curable component, heating at a temperature of more than 100°C, preferably more than 120°C, is required to cure the insulating film for forming the touch panel. When an insulating layer is formed on a substrate on which an organic EL element is formed, there is the inconvenience that heating at a temperature of more than 100°C, especially more than 120°C, leads to deterioration of the organic light-emitting layer. On the other hand, when an insulating film is formed using conventional materials by heating at 120°C or less, particularly at 100°C or less, the resulting insulating film tends to be incapable of withstanding the etching solution and oxygen ashing used for wiring formation, making it difficult to fabricate a touch panel structure. There is a demand for the development of a radiation-sensitive composition that can obtain a cured film that has sufficient etching solution resistance and oxygen ashing resistance even when heated at a relatively low temperature, not only for insulating films for organic EL devices with touch panels, but also for various applications such as insulating films for other display devices.

The present invention has been made based on the above circumstances, and aims to provide a radiation-sensitive composition that has sufficient lithography performance and can give a cured film that has sufficient etching solution resistance and oxygen ashing resistance even when heated at a relatively low temperature (for example, 120°C or lower), an insulating film for a display device and a display device obtained using the radiation-sensitive composition, a method for forming an insulating film for a display device using the radiation-sensitive composition, and a polymer suitable as a component of the radiation-sensitive composition.

The invention made to solve the above-mentioned problems is a radiation-sensitive resin composition comprising: (A) a polymer containing an aromatic ring or a fused ring and having a weight average molecular weight of 500 to 100,000, the polymer having at least one group selected from the group represented by the following formulae (1a), (1b), (2a) and (2b); (B) a radiation-sensitive radical initiator; and (C) an organic solvent.

(In the formula, Z represents a sulfur atom or -NR ¹⁰ -, where R ¹⁰ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ¹ represents a hydrogen atom or a group represented by formula (3). R ⁵ represents a divalent organic group, R ² represents a monovalent organic group, and R ³ represents a divalent organic group. * represents a bonding position.)

Another invention made to solve the above problems is an insulating film for a display device formed from the radiation-sensitive composition.

Yet another invention made to solve the above problem is a display device having the insulating film for a display device.

Yet another invention made to solve the above problem is a method for forming an insulating film for a display device, comprising the steps of forming a coating film directly or indirectly on a substrate, irradiating at least a portion of the coating film with radiation, developing the coating film, and heating the coating film, in this order, and the coating film is formed from the radiation-sensitive composition.

Still another invention made to solve the above problems is a polymer having a first structural unit represented by the following formula (5a) and a second structural unit represented by the following formula (5b).

(In formulas (5a) and (5b), ^R7 represents a methylene group or an alkylene group having 2 to 12 carbon atoms. ^R8 represents a hydrogen atom or a methyl group.)

The present invention provides a radiation-sensitive composition that has sufficient lithography performance and can give a cured film that has sufficient etching solution resistance and oxygen ashing resistance even when heated at a relatively low temperature, an insulating film for a display device and a display device obtained using the radiation-sensitive composition, a method for forming an insulating film for a display device using the radiation-sensitive composition, and a polymer suitable as a component of the radiation-sensitive composition.

FIG. 1 is a cross-sectional view that illustrates a schematic diagram of an organic EL device with a touch panel according to an embodiment of the present invention.

<Radiation-sensitive composition>
A radiation-sensitive composition according to one embodiment of the present invention includes (A) a polymer, (B) a radiation-sensitive radical polymerization initiator, and (C) an organic solvent. The radiation-sensitive composition may further include (D) a polymerizable compound and other optional components. Each component will be described in detail.

The polymer (A) in the radiation-sensitive composition is a polymer containing an aromatic ring or a condensed ring and having a weight-average molecular weight of 1000 to 100,000, and having at least one group selected from the group of the following formulae (1a), (1b), (2a) and (2b). By including such a polymer, the composition can be cured at a temperature lower than the curing temperature of conventional curable compositions, exhibiting excellent curability, and can also exhibit sufficient lithography performance.

(In the formula, Z represents a sulfur atom or -NR ¹⁰ -, where R ¹⁰ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ¹ represents a hydrogen atom or a group represented by formula (3). R ⁵ represents a divalent organic group, R ² represents a monovalent organic group, and R ³ represents a divalent organic group. * represents a bonding position.)

The polymer (A) in the radiation-sensitive composition contains an aromatic ring or a condensed ring, and is obtained by subjecting an epoxy resin that has been acid-modified with (meth)acrylic acid or the like to an addition reaction with a thiol compound. For example, the polymer obtained by the reaction formula shown below can be given.

In the formula, ^R7 represents a methylene group or an alkylene group having 2 to 12 carbon atoms, and ^R8 represents a hydrogen atom or a methyl group.
Examples of the polymer containing an aromatic ring or a condensed ring and having a weight average molecular weight of 500 to 100,000 include acid-modified cresol novolac type epoxy (meth)acrylate resin, phenol novolac type epoxy (meth)acrylate resin, bisphenol A type epoxy (meth)acrylate resin, bisphenol F type epoxy (meth)acrylate resin, biphenyl type epoxy (meth)acrylate resin, trisphenolmethane type epoxy (meth)acrylate resin, and cardo type resin.

Among the above-mentioned polymers (A), an acid-modified cresol novolac type epoxy (meth)acrylate resin is particularly preferred. In the acid-modified cresol novolac type epoxy (meth)acrylate resin, the polymerizable monomer preferably has a novolac skeleton in the unit structure.
The polymerizable monomer having a novolac skeleton is not particularly limited, and examples thereof include novolac epoxy (meth)acrylates such as phenol novolac epoxy (meth)acrylate, o-cresol novolac epoxy (meth)acrylate, m-cresol novolac epoxy (meth)acrylate, p-cresol novolac epoxy (meth)acrylate, naphthol-modified novolac epoxy (meth)acrylate, and halogenated phenol novolac epoxy (meth)acrylate. The general formula representing the novolac epoxy (meth)acrylate is shown in the following formula (6).

(In formula (6), R ⁹ represents a hydrogen atom or a methyl group, R ¹⁰ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R ¹¹ represents an atomic group derived from a polybasic acid anhydride and having a carboxyl group, and m and n each represent 0 or a positive integer.)

The polybasic acid anhydride is not particularly limited, and examples thereof include succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, itaconic anhydride, pyromellitic anhydride, trimellitic anhydride, etc. Among these, succinic anhydride, tetrahydrophthalic anhydride, and phthalic anhydride are preferred in terms of reactivity.

When the novolac epoxy (meth)acrylate has an alkali-soluble functional group, the preferred upper limit of the oxidation of the novolac epoxy (meth)acrylate is 250 mg KOH/g. If the oxidation of the novolac epoxy (meth)acrylate having the alkali-soluble functional group exceeds 250 mg KOH/g, the adhesion may decrease. A more preferred upper limit of the oxidation of the novolac epoxy (meth)acrylate having the alkali-soluble functional group is 200 mg KOH/g.

The commercially available novolac epoxy (meth)acrylate is not particularly limited, and examples thereof include EA-1020, EA-1025, EA-1026, EA-1028, EA-6320, EA-6340 (all manufactured by Shin-Nakamura Chemical Co., Ltd.), Ebecryl 150, Ebecryl 1150 (all manufactured by Daicel-Cytec Co., Ltd.), M-208, M 210 (all manufactured by Toa Gosei Co., Ltd.), PNA-161H, CNA-142H, PCR-1169 H, CCR-1159H, CCR-1358H, CCR-1316H (all manufactured by Nippon Kayaku Co., Ltd.), Epicron N-695, Epicron N-775 (all manufactured by DIC Corporation), PR-300, PR -310, PR-320, HRM-1004, HRM-1005, HRM-1011, HRM-1013, HRM-2019, HRM-2021, HRM-2027, HRM-2031 (all manufactured by Showa Polymer Co., Ltd.), Kyoeisha's "Epoxy Ester EX-5060P", etc.

Addition reaction methods include Michael addition reaction and enethiol reaction, with Michael addition reaction being preferred. Compounds to be added include monovalent thiol compounds and monovalent amine compounds, with monovalent thiol compounds being preferred. Specifically, compounds represented by the following formulae (SH-1) to (SH-4) are included, with the compound represented by the following formula (SH-1) being preferred.

Examples of bases used in the Michael addition reaction include trimethylamine, triethylamine, tripropylamine, imidazole, diazabicycloundecene, pyridine, morpholine, piperazine, piperidine, sodium hydroxide, potassium hydroxide, etc., with triethylamine being preferred.

The acid-modified novolac epoxy (meth)acrylate resin is reacted with at least one of the compounds represented by the above formulas (SH-1) to (SH-3) by addition reaction to introduce a substituent, which is at least one group selected from the group of the above formulas (1a), (1b), (2a) and (2b). By having such a substituent, the composition can be cured at a temperature lower than the curing temperature of conventional curable compositions, exhibiting excellent curability, and can also exhibit sufficient lithography performance.

The preferred lower limit of the weight-average molecular weight of the polymer (A) is 1,000, and the preferred upper limit is 100,000. If the weight-average molecular weight of the polymer (A) is less than 1,000, the amount of unreacted low molecular weight compounds in the resin increases, and the remaining low molecular weight compounds may dissolve into the liquid crystal, causing display defects in the panel. If the upper limit exceeds 100,000, residues may be generated during development, or the resulting protrusions may not be arched.

((B) Radiation-sensitive radical polymerization initiator)
Examples of the radiation-sensitive radical polymerization initiator (B) include compounds capable of generating active species capable of initiating a radical polymerization reaction of the polymer (A) upon exposure to radiation such as visible light, ultraviolet light, far ultraviolet light, electron beams, X-rays, etc. The radiation-sensitive radical polymerization initiator (B) may be used alone or in combination of two or more kinds.

(B) Specific examples of radiation-sensitive radical polymerization initiators include O-acyloxime compounds, α-aminoketone compounds, α-hydroxyketone compounds, acylphosphine oxide compounds, etc.

Examples of O-acyloxime compounds include 1-[9-ethyl-6-(2-methylbenzoyl)-9.H.-carbazol-3-yl]-ethan-1-one oxime-O-acetate, 1-[9-ethyl-6-benzoyl-9.H.-carbazol-3-yl]-octan-1-one oxime-O-acetate, 1-[9-ethyl-6-(2-methylbenzoyl)-9.H.-carbazol-3-yl]-ethan-1-one oxime-O-benzoate, 1-[9-n-butyl-6-(2-ethylbenzoyl)-9.H.-carbazol-3-yl]-ethan-1-one oxime-O-benzoate, ethanone, 1-[9-ethyl-6-(2-methyl-4-tetrahydrofuranylbenzoyl)-9.H. -Carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-(2-methyl-4-tetrahydropyranylbenzoyl)-9. H. -Carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-(2-methyl-5-tetrahydrofuranylbenzoyl)-9. H. -Carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl}-9. H. -Carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-(2-methyl-4-tetrahydrofuranylmethoxybenzoyl)-9. H. -carbazol-3-yl]-, 1-(O-acetyloxime), 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], etc.

Examples of α-aminoketone compounds include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone, and 1-[4-(2-hydroxyethylsulfanyl)phenyl]-2-methyl-2-(4-morpholino)propan-1-one.

Examples of α-hydroxyketone compounds include 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-(4-i-propylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, and 1-hydroxycyclohexylphenylketone.

Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

As the (B) radiation-sensitive radical polymerization initiator, from the viewpoint of further accelerating the curing reaction by radiation, O-acyloxime compounds, α-aminoketone compounds, and acylphosphine oxide compounds are preferred, O-acyloxime compounds and α-aminoketone compounds are more preferred, and O-acyloxime compounds are even more preferred.

The lower limit of the content of the radiation-sensitive radical polymerization initiator (B) in the radiation-sensitive composition is preferably 5 parts by mass, more preferably 10 parts by mass, even more preferably 15 parts by mass, even more preferably 20 parts by mass, and even more preferably 30 parts by mass, relative to 100 parts by mass of the polymer (A). On the other hand, the upper limit of this content is preferably 150 parts by mass, more preferably 100 parts by mass, even more preferably 70 parts by mass, even more preferably 60 parts by mass, and even more preferably 50 parts by mass. By setting the content of the radiation-sensitive radical polymerization initiator (B) to the above lower limit or more and the above upper limit or less, more sufficient lithography performance and curability can be exhibited.

((C) Organic Solvent)
The organic solvent (C) is not particularly limited, and examples thereof include alcohol solvents, ether solvents, ester solvents, ketone solvents, etc. The organic solvent (C) may be used alone or in combination of two or more kinds.

Examples of alcohol-based solvents include alkyl alcohols such as methanol, ethanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, t-butyl alcohol, 1-hexanol, 1-octanol, 1-nonanol, 1-dodecanol, 1-methoxy-2-propanol, and diacetone alcohol;
Examples of the alcohol include aromatic alcohols such as benzyl alcohol.

Examples of the ether solvent include ethylene glycol monoalkyl ethers such as diethylene glycol methyl ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether;
propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether;
diethylene glycol monoalkyl ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether;
diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether and diethylene glycol ethyl methyl ether;
Examples of the dipropylene glycol monoalkyl ethers include dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and dipropylene glycol monobutyl ether.

Examples of the ester solvent include carboxylic acid esters such as ethyl acetate, i-propyl acetate, n-butyl acetate, amyl acetate, ethyl lactate, methyl 3-methoxypropionate, and ethyl 3-ethoxypropionate;
Polyhydric alcohol carboxylate solvents such as propylene glycol diacetate;
Examples of suitable solvents include polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate.

Examples of ketone solvents include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and cycloheptanone.

Among these, ether-based solvents and ester-based solvents are preferred, ester-based solvents are more preferred, and polyhydric alcohol partial ether carboxylate-based solvents are even more preferred. Among the ether-based solvents and ester-based solvents, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, and methyl 3-methoxypropionate are preferred.

The content of the (C) organic solvent in the radiation-sensitive composition is not particularly limited, but it is preferable that the solid content is adjusted to be within the following range. The lower limit of the solid content in the radiation-sensitive composition is preferably 5% by mass, more preferably 10% by mass, and even more preferably 20% by mass. On the other hand, the upper limit of the solid content is preferably 60% by mass, more preferably 50% by mass, and even more preferably 40% by mass.

((D) Polymerizable Compound)
When the radiation-sensitive composition contains the polymerizable compound (D), the etching solution resistance and oxygen ashing resistance of the resulting cured film can be further improved. The polymerizable compound (D) is a compound having a plurality of polymerizable groups. However, the polymerizable compound (D) does not include the polymer (A). The polymerizable compound (D) is preferably a monomer, i.e., a non-polymer.

Examples of the polymerizable group possessed by the (D) polymerizable compound include a (meth)acryloyl group, a vinyl group, an N-alkoxymethylamino group, an oxiranyl group (epoxy group), an oxetanyl group, and an N-alkoxymethylamino group, with a (meth)acryloyl group and an N-alkoxymethylamino group being preferred, and a (meth)acryloyl group being more preferred. The lower limit of the number of polymerizable groups possessed by the (D) polymerizable compound is 2. On the other hand, the upper limit is not particularly limited, and may be, for example, 20, with 12 being preferred, and 8 being more preferred. As the (D) polymerizable compound, a compound having multiple (meth)acryloyl groups and a compound having multiple N-alkoxymethylamino groups are preferred, and a compound having multiple (meth)acryloyl groups is more preferred.

Examples of compounds having multiple (meth)acryloyl groups include a reaction product of an aliphatic polyhydroxy compound with (meth)acrylic acid [polyfunctional (meth)acrylate], a caprolactone-modified polyfunctional (meth)acrylate, an alkylene oxide-modified polyfunctional (meth)acrylate, a reaction product of a (meth)acrylate having a hydroxyl group with a polyfunctional isocyanate [polyfunctional urethane (meth)acrylate], a reaction product of a (meth)acrylate having a hydroxyl group with an acid anhydride [polyfunctional (meth)acrylate having a carboxyl group], etc. Among these, a reaction product of an aliphatic polyhydroxy compound with (meth)acrylic acid [polyfunctional (meth)acrylate] is preferred. Specific examples of aliphatic polyhydroxy compounds, (meth)acrylates having a hydroxyl group, polyfunctional isocyanates, and acid anhydrides include the compounds described in paragraph [0065] of JP 2015-232694 A, and examples of caprolactone-modified polyfunctional (meth)acrylates and alkylene oxide-modified polyfunctional (meth)acrylates include the compounds described in paragraph [0066] of the same publication.

Specific examples of compounds having multiple (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, succinic acid modified pentaerythritol tri(meth)acrylate, 2-hydroxyethane-1,1,1-triyltrismethylene tri(meth)acrylate, tris(2-(meth)acryloyloxyethyl) isocyanurate, trimethylolpropane polypropylene glycol tri(meth)acrylate, etc.

Examples of compounds having multiple N-alkoxymethylamino groups include compounds having a melamine structure, a benzoguanamine structure, or a urea structure. Specific examples of these include the compounds described in paragraph [0067] of JP 2015-232694 A.

The lower limit of the content of the polymerizable compound (D) in the radiation-sensitive composition is preferably 30 parts by mass, more preferably 100 parts by mass, even more preferably 200 parts by mass, and even more preferably 220 parts by mass, relative to 100 parts by mass of the polymer (A). By making the content of the polymerizable compound (D) equal to or greater than the above lower limit, it is possible to further increase the etching solution resistance and oxygen ashing resistance of the obtained cured film. On the other hand, the upper limit of this content is preferably 1,000 parts by mass, more preferably 600 parts by mass, even more preferably 400 parts by mass, even more preferably 300 parts by mass, and even more preferably 260 parts by mass. By making the content of the polymerizable compound (D) equal to or less than the above upper limit, it is possible to further improve lithography performance.

(Other ingredients)
The radiation-sensitive composition may further contain other components other than the above-mentioned (A) polymer, (B) radiation-sensitive radical polymerization initiator, (C) organic solvent, and (D) polymerizable compound. Examples of such other components include a curing agent, a curing accelerator, an adhesion aid, an antioxidant, a surfactant, etc. However, the content ratio of other components other than the (A) polymer, (B) radiation-sensitive radical polymerization initiator, (C) organic solvent, and (D) polymerizable compound in the radiation-sensitive composition may be preferably 10% by mass or less, and may be more preferably 1% by mass or less.

(Curing temperature)
As described above, the radiation-sensitive composition can provide a cured film having sufficient etching solution resistance and oxygen ashing resistance even by heating at a relatively low temperature. The radiation-sensitive composition is preferably a composition that can be cured by heating at a temperature range of, for example, 60° C. to 120° C., and more preferably a composition that can be cured by heating at a temperature range of 60° C. to 100° C.

(Method of Preparing Radiation-Sensitive Composition)
The radiation-sensitive composition can be prepared by mixing the components in a predetermined ratio and dissolving the mixture in an organic solvent (C). The prepared composition is preferably filtered through a filter having a pore size of about 0.2 μm.

<Insulating film for display device>
The insulating film for a display device according to one embodiment of the present invention is a cured film formed from the radiation-sensitive composition. The insulating film for a display device may be a patterned film. The insulating film for a display device is formed from a radiation-sensitive composition that can provide a cured film having sufficient etching solution resistance and oxygen ashing resistance even by heating at a relatively low temperature, and therefore has a high yield and excellent durability.

The insulating film for a display device is suitable as an interlayer insulating film, and may also be used as a planarizing film, a spacer, a protective film, etc. The insulating film for a display device can be used in display devices such as display devices equipped with liquid crystal display elements (liquid crystal display devices), display devices equipped with organic EL elements (organic EL devices), and electronic paper. As described below, the insulating film for a display device is also suitable as an interlayer insulating film for a touch panel in a display device equipped with a touch panel, such as an organic EL device equipped with a touch panel.

Even if the insulating film for a display device is relatively thick, cracks are unlikely to occur. Therefore, the insulating film for a display device can be made thicker. The lower limit of the average thickness of the insulating film for a display device may be, for example, 0.1 μm, but is preferably 0.5 μm, more preferably 1 μm, and even more preferably 2 μm. On the other hand, the upper limit of this average thickness is, for example, 10 μm, and may be 6 μm or 4 μm.

<Display Device>
A display device according to an embodiment of the present invention has the insulating film for a display device. Examples of the display device include a liquid crystal display device, an organic EL device, electronic paper, etc. Among these, the display device according to an embodiment of the present invention is preferably an organic EL device.

The organic EL device includes an organic EL element. The organic EL element usually has a laminated structure including an anode layer, an organic light-emitting layer, and a cathode layer. The organic EL device preferably includes a touch panel laminated on a substrate having an organic EL element. The insulating film for a display device according to one embodiment of the present invention is preferably used for at least a part of the insulating film in the touch panel. In particular, the insulating film for a display device according to one embodiment of the present invention is preferably used for the insulating film of the touch panel laminated on a substrate having an organic EL element without an adhesive layer or a bonding layer. In this way, the touch panel can be directly laminated on the substrate on which the organic EL element is formed, making it possible to make the organic EL device with a touch panel thinner. In addition, the radiation-sensitive composition can obtain a cured film having sufficient etching solution resistance and oxygen ashing resistance even by heating at a relatively low temperature, so that deterioration of the organic EL element in the manufacturing process can be suppressed and the yield can be increased. In addition, since the insulating film can be formed by heating at a relatively low temperature using the radiation-sensitive composition in this way, deterioration of the organic EL element in the manufacturing process can be suppressed, and the radiation-sensitive composition can be particularly suitably used for forming an insulating film in various organic EL devices equipped with an organic EL element other than an organic EL device with a touch panel.

Figure 1 shows one form of an organic EL device with a touch panel. The organic EL device with a touch panel 10 in Figure 1 includes an organic EL display substrate 20 and a touch panel 30. The organic EL display substrate 20 has a structure in which a support substrate 21, an anode layer 22, an organic light-emitting layer 23, a cathode layer 24, an adhesive layer 25, and a sealing substrate 26 are laminated in this order. Note that at least the anode layer 22, the organic light-emitting layer 23, and the cathode layer 24 constitute an organic EL element. For example, the organic light-emitting layer 23 may have a structure in which, from the anode layer 22 side, a hole injection layer, a hole transport layer, an organic EL light-emitting layer, an electron transport layer, and an electron injection layer are laminated in this order.

The touch panel 30 is a capacitance type in which a first sensor electrode 31, an interlayer insulating film 33, and a second sensor electrode 32 are laminated in this order. The touch panel 30 has the first sensor electrode 31, the second sensor electrode 32 arranged facing the first sensor electrode 31, the interlayer insulating film 33, and a transparent substrate 34 arranged on the outermost surface. In this embodiment, the first sensor electrode 31 is formed directly on the sealing substrate 26 of the organic EL display substrate 20. The interlayer insulating film 33 is a transparent insulating film that insulates the first sensor electrode 31 and the second sensor electrode 32, and is formed from the radiation-sensitive composition. Note that the touch panel is not limited to such a capacitance type.

<Method of forming insulating film for display device>
A method for forming an insulating film for a display device according to one embodiment of the present invention includes, in this order, a step of forming a coating film directly or indirectly on a substrate (hereinafter also referred to as a "coating film forming step"), a step of irradiating (exposing) at least a part of the coating film with radiation (hereinafter also referred to as a "radiation irradiation step"), a step of developing the coating film (hereinafter also referred to as a "developing step"), and a step of heating the coating film (hereinafter also referred to as a "heating step"), and the coating film is formed from a radiation-sensitive composition according to one embodiment of the present invention. The formation method may include, as an optional step, a step of heating the coating film (hereinafter also referred to as a "PEB step") between the radiation irradiation step and the development step.

According to this formation method, since the radiation-sensitive composition described above is used, it is possible to pattern an insulating film with a good shape, and even when heated at a relatively low temperature, it is possible to obtain an insulating film that has sufficient resistance to etching solutions and oxygen ashing. Furthermore, even if the substrate on which the coating film is formed contains an organic EL element, it is possible to suppress deterioration of the organic EL element by performing the heating process at a relatively low temperature. Each process will be described below.

(Coating film forming process)
In this step, the radiation-sensitive composition is applied directly or via another layer onto a substrate, and then the applied surface is preferably heated (prebaked) to remove the organic solvent and the like to form a coating film. Examples of the material of the substrate include glass, quartz, silicon, and resin. Specific examples of the resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, polyimide, addition polymers of cyclic olefins, ring-opening polymers of cyclic olefins, and hydrogenated products thereof.

The substrate may include an organic EL element or the like. The substrate may also have electrodes, wiring, and the like provided on the coated surface. An example of such a substrate is the organic EL display substrate 20 in FIG. 1 described above, on which the first sensor electrode 31 is formed.

The method for applying the radiation-sensitive composition is not particularly limited, and any suitable method such as spraying, roll coating, rotary coating (spin coating), slit die coating, bar coating, etc., can be used. Among these coating methods, spin coating and slit die coating are particularly preferred. The pre-baking conditions vary depending on the types and blending ratios of each component, but may be, for example, a heating time of 1 to 10 minutes at a temperature of 60°C to 120°C, more preferably 100°C or less.

(Radiation Irradiation Step)
In this step, radiation is irradiated to at least a part of the coating film formed in the coating film forming step. Usually, radiation is irradiated through a photomask having a predetermined pattern when a part of the coating film is irradiated with radiation. Examples of the radiation that can be used include visible light, ultraviolet light, far ultraviolet light, electron beams, and X-rays. Among these radiations, radiation having a wavelength in the range of 190 nm to 450 nm is preferred, and radiation containing ultraviolet light of 365 nm is more preferred.

The lower limit of the exposure dose in this step is preferably 10 mJ/ ^cm2 , more preferably 50 mJ/ ^cm2 , as a value measured by an illuminometer ("OAI model 356" from OAI Optical Associates Inc.) for the intensity of radiation at a wavelength of 365 nm. The upper limit of the exposure dose is preferably 2,000 mJ/ ^cm2 , more preferably 1,000 mJ/ ^cm2 , as a value measured by the illuminometer.

(PEB process)
When a PEB step is performed, the PEB conditions vary depending on the types and blending ratios of each component, but may be, for example, a heating temperature of 60° C. to 120° C., more preferably 100° C. or less, for a heating time of 1 minute to 10 minutes.

(Developing process)
In this process, the coating film after irradiation is developed with a developer to form a predetermined pattern. The developer is preferably an alkaline developer. Examples of the alkaline developer include an alkaline aqueous solution in which at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, tetramethylammonium hydroxide, and tetraethylammonium hydroxide is dissolved. In addition, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol or a surfactant may be added to the alkaline developer.

As a developing method, for example, a suitable method such as a puddle method, a dipping method, a swing immersion method, a spray method, etc. can be used. The developing time varies depending on the composition of the radiation-sensitive composition, but is, for example, from 10 seconds to 180 seconds. Following such a developing process, for example, washing with running water is performed for a processing time of from 30 seconds to 90 seconds, and then the desired pattern can be formed by air drying with, for example, compressed air or compressed nitrogen.

(Heating process)
In this step, the coating film that has been developed and patterned is heated (post-baked) using a heating device such as a hot plate or oven to obtain an insulating film for a display device having a desired pattern. Between the development step and the heating step, the coating film may be irradiated with radiation such as ultraviolet rays. The exposure amount at this time may be, for example, 100 mJ/cm ² or more and 2,000 mJ/cm ² or less. The lower limit of the heating temperature is preferably 60° C., and may be 80° C. By setting the heating temperature to the lower limit or more, a sufficiently cured insulating film can be obtained. On the other hand, the upper limit of the heating temperature is preferably 120° C., and more preferably 100° C. By setting the heating temperature to the lower limit or more, for example, a sufficiently cured insulating film can be obtained while suppressing deterioration of an organic EL element provided on the substrate. In addition, by setting the heating temperature to the upper limit or less, excessive stress generation such as sudden film shrinkage can be suppressed, and therefore the occurrence of cracks can be suppressed. Thus, in the heating step, it is preferable to perform heating in a temperature range of 60° C. to 120° C. The heating time varies depending on the type of heating device, but for example, when heating on a hot plate, it may be 5 to 30 minutes, and when heating in an oven, it may be 10 to 90 minutes. The heating may be performed in air or in an inert gas atmosphere such as nitrogen or argon. It is also possible to use a step bake method in which two or more heating steps are performed.

(Other processes)
When manufacturing a touch panel or the like having the insulating film for a display device, after forming the insulating film for a display device, other processes are performed to form further electrodes, wiring, etc. (for example, the second sensor electrode 32 in the touch panel 30 of FIG. 1). Such processes include an electrode forming process, a wiring forming process, an etching process, an ashing process, etc. For forming the electrodes and wiring, a known method such as printing or vapor deposition can be adopted. Etching can be performed using a known etching solution such as an amine-based solution. Ashing can be performed by a known ashing method such as oxygen ashing. Note that when manufacturing a touch panel or the like, the formation of the insulating film and the formation of the electrodes, wiring, etc. may each be performed multiple times.

<Polymer>
The polymer of the present invention is a polymer having at least two or more structural units represented by the following formulas (5a), (5b), (5c) and (5d).


In formulae (5a), (5b), (5c), and (5d), ^R7 represents a methylene group or an alkylene group having 2 to 12 carbon atoms. ^R8 represents a hydrogen atom or a methyl group. Among (5a), (5b), (5c), and (5d), a combination of structural units represented by (5a) and (5b) and a combination of structural units represented by (5c) and (5d) are preferred.

The polymer can be suitably used as a component of a radiation-sensitive composition for forming an insulating film for a display device. The polymer is a suitable form of the polymer (A) in the radiation-sensitive composition according to one embodiment of the present invention described above.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Weight average molecular weight (Mw)]
The Mw was measured by gel permeation chromatography (GPC) under the following conditions.
Apparatus: Showa Denko's "GPC-101"
Column: Showa Denko's "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" connected together Mobile phase: Tetrahydrofuran 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

The following is an example of the synthesis of polymer (A). Polymer (A) can be obtained by subjecting acid-modified epoxy resin to a Michael addition reaction with a thiol compound. Examples of acid-modified epoxy resins are shown below. Polymer (A) of the present invention is not limited to the acid-modified epoxy resins shown below.

(E-1): Nippon Kayaku's "CCR-1358H"
Acid anhydride modified cresol novolac type epoxy acrylate resin (E-2): "CCR-1316H" by Nippon Kayaku Co., Ltd.
Acid anhydride-modified cresol novolac epoxy acrylate resin (E-3): Kyoeisha's "Epoxy Ester EX-5060P"
Acid-modified cardo-based resin cresol novolac type epoxy acrylate resin having acryloyl and carboxy groups

The thiol group-containing compounds used in the Michael addition reaction were Compound (SH-1) to Compound (SH-4) shown below.

Synthesis Example 1 Synthesis of Polymer (A-1-1) Using Michael Addition Reaction In a 1 L three-neck Classco equipped with a thermometer, 200 g of CCR-1358H (manufactured by Nippon Kayaku Co., Ltd., solids concentration 50.5%, propylene glycol monomethyl ether acetate solution, 100 mol% calculated as (meth)acryloyl groups) and 8.38 g (25 mol%) of mercaptopropionic acid were added, and 16.0 g (50 mol%) of triethylamine was slowly added, followed by stirring at 50° C. for 5 hours.
After the reaction was completed, 1 L of ethyl acetate and 1 L of 1M aqueous hydrochloric acid were added to remove the aqueous layer, and the mixture was washed with water three times. Next, the solvent was replaced twice with propylene glycol monomethyl ether acetate to obtain 205 g of polymer (A-1) having a solid content of 50%. The structure was confirmed by ¹ H-NMR and FT-IR.

The polymers (A-2) to (A-5) obtained in [Synthesis Examples 2] to [Synthesis Examples 5] were prepared in the same manner as in Synthesis Example 1, except that the type and amount of the thiol compound were changed as shown in Table 1.

[Synthesis Example 6]
In a 1 L three-necked Classco equipped with a thermometer, 150 g of epoxy ester EX-5060P (Kyoeisha, solid content concentration 59.9%, propylene glycol monomethyl ether acetate solution, 100 mol% calculated as (meth)acryloyl group) and 16.5 g (50 mol%) of mercaptopropionic acid were added, and 31.4 g (100 mol%) of triethylamine was slowly added, followed by stirring at 50°C for 5 hours. After completion of the reaction, 1 L of ethyl acetate and 1 L of 1M hydrochloric acid were added to remove the aqueous layer, followed by washing with water three times. Next, solvent replacement was performed twice with propylene glycol monomethyl ether acetate to obtain 201 g of polymer (A-6) with a solid content concentration of 50%. The structure was confirmed by ¹ H-NMR and FT-IR.
[Synthesis Example 7], [Synthesis Example 8]
The same procedure as in Synthesis Example 6 was repeated except that the type and amount of the thiol compound were changed as shown in Table 1.
Polymer (A-8) was obtained from polymer (A-7).

The components used in preparing the radiation-sensitive compositions of the Examples and Comparative Examples are shown below.
(A) Polymers (A-1) to (A-8)
Polymers (A-1) to (A-8) Synthesized in Synthesis Examples 1 to 8

(B) Radiation-sensitive radical polymerization initiator (B-1): Oxime-based photoradical polymerization initiator ("NCI-930" from ADEKA Corporation)
(B-2): "IrgacureOxe01" from BASF Japan
(B-3): Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (B-4): 2-(dimethylamino)-1-(4-morpholinophenyl)-2-benzyl-1-butanone (B-5): 1-[4-(2-hydroxyethylsulfanyl)phenyl]-2-methyl-2-(4-morpholino)propan-1-one

(D) Polymerizable Compound (D-1): 2-hydroxyethane-1,1,1-triyltrismethylene triacrylate (D-2): pentaerythritol tetraacrylate (D-3): dipentaerythritol hexaacrylate (D-4): tris(2-acryloyloxyethyl) isocyanurate
(D-5): Trimethylolpropane polypropylene glycol triacrylate

(R) Polymer used in comparative example (RA-1): "CCR-1358H" from Nippon Kayaku Co., Ltd.
Acid anhydride modified cresol novolac type epoxy acrylate resin (RA-2): "CCR-1316H" by Nippon Kayaku Co., Ltd.
Acid anhydride modified cresol novolac type epoxy acrylate resin (RA-3): "WR-301" by ADEKA Corporation
Acid-modified cardo resin having acryloyl and carboxy groups

Preparation Example 1 Preparation of Radiation-Sensitive Composition (C-1) 200 parts by mass of propylene glycol monomethyl ether acetate (PGMEA) containing (A-1) as a polymer (100 parts by mass of (A-1) as a resin solid content), 5 parts by mass of (B-1) as a radiation-sensitive radical polymerization initiator (B), and 0.15 parts by mass of a surfactant (DOWSIL 8019 Additive from Dow Corning Toray Co., Ltd.) were mixed. The mixture was then diluted with PGMEA to a total solid content concentration of 30% by mass, and filtered through a membrane filter having a pore size of 0.2 μm to prepare radiation-sensitive composition (C-1).

[Preparation Examples 2 to 36 , Comparative Preparation Examples 1 to 3] Preparation of radiation-sensitive compositions (C-2) to (C- 36 ) and (R-1) to (R-3) Radiation-sensitive compositions (C-2) to (C-36) and (R-1) to (R-3) of Preparation Examples 2 to 36 and Comparative Preparation Examples 1 to 3 were prepared in the same manner as Preparation Example 1, except that the types and amounts of each component shown in Table 2 were used instead of 100 parts by mass of (A- 1 ) and 30 parts by mass of (B-1) in Preparation Example 1. A blank column in Table 2 indicates that the component was not used.

[Example 1]
(Formation of insulating film)
The radiation-sensitive composition (C-1) was spin-coated on a silicon substrate to a thickness of 2.0 μm. Then, the substrate was pre-baked at 85° C. for 2 minutes using a hot plate to form a coating film. This coating film was exposed to light by a scanning method (illuminance=500 mW, NA=0.10, λ=ghi line, 120 mJ/cm ² ) using a SUS DSC-200 through a 5 μm×5 μm square hole pattern mask. Then, the substrate was developed at 25° C. for 1 minute using an aqueous tetramethylammonium hydroxide solution (concentration 2.38%). Then, the substrate was washed with running water and dried to form a pattern on the substrate. Next, the substrate was irradiated with 600 mJ/cm ² ultraviolet light using a TOPCON TME-400PRJ with ghi mixed rays, and further heated in an oven at 85° C. for 60 minutes to obtain an insulating film with an average thickness of 2.0 μm.

(Evaluation of Lithography Performance)
The insulating film (patterned thin film) obtained by the above method was observed with a scanning electron microscope (SEM) for the presence or absence of residues in holes and the dimensions of the bottoms, and was evaluated according to the following criteria. The evaluation results are shown in Table 3.
A: No residue, and bottom dimension is 3 μm or more. B: No residue, and bottom dimension is 2 μm or more and less than 3 μm. C: No residue, and bottom dimension is 1 μm or more and less than 2 μm. D: Residue is present, or no residue is present, and bottom dimension is less than 1 μm.

(Evaluation of etching chemical resistance)
The silicon substrate on which the insulating film was formed by the above method was immersed in an amine-based stripping solution (etching solution) at 60° C. for 60 seconds. The insulating film was evaluated according to the following criteria based on the film thickness ratio before and after immersion ((film thickness after immersion/film thickness before immersion)×100%). The evaluation results are shown in Table 3.
A: 95% or more and less than 97%, or 103% or more and less than 105% B: Less than 95%, or 105% or more C: The insulating film peels off

(Evaluation of oxygen ashing resistance)
When forming the insulating film, exposure was performed over the entire surface without using a 5 μm×5 μm square hole pattern mask, forming an insulating film with an average thickness of 2.0 μm. The insulating film thus formed on the silicon substrate was ashed under predetermined conditions (300 W, 30 s, O2 30 (SCCM), 25° C.), and the remaining film rate ((average film thickness after ashing/average film thickness before ashing)×100%) was measured and evaluated according to the following criteria. The evaluation results are shown in Table 3.
A: 93% or more B: 90% or more but less than 93% C: Less than 90%

As shown in Table 3, it can be seen that Examples 1 to 40 have sufficient lithography performance (A to C), and can form cured films (insulating films) that have sufficient etching solution resistance (A to C) and sufficient oxygen ashing resistance (A to C) even when heated to 120° C. or less.

The radiation sensitivity of the present invention makes it suitable for use as a material for forming insulating films, etc. in display devices.

REFERENCE SIGNS LIST 10: organic EL device with touch panel 20: organic EL display substrate 21: support substrate 22: anode layer 23: organic light-emitting layer 24: cathode layer 25: adhesive layer 26: sealing substrate 30: touch panel 31: first sensor electrode 32: second sensor electrode 33: interlayer insulating film 34: transparent substrate

Claims (9)

(A ) a polymer having a weight average molecular weight of 1,000 to 100,000, represented by the following formula (7): (B) a radiation-sensitive radical initiator; and (C) an organic solvent.

(In formula (7), R ⁸ represents a hydrogen atom or a methyl group. R ¹⁰ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. R ¹² represents --R ⁷ --COOH or a group represented by the following formula. R ⁷ represents a methylene group or an alkylene group having 2 to 12 carbon atoms.)

The radiation -sensitive composition for an insulating film of a display device according to claim 1 , further comprising (D) a polymerizable compound. An insulating film for a display device, formed from the radiation-sensitive composition for an insulating film of a display device according to claim 1 or 2 . A display device comprising the insulating film for a display device according to claim 3 . 5. The display device of claim 4 which is an organic electroluminescent device. The display device according to claim 5 , which is an organic electroluminescence device with a touch panel. A step of directly or indirectly forming a coating film on a substrate;
irradiating at least a portion of the coating with radiation;
A method for forming an insulating film for a display device, comprising the steps of: developing the coating film; and heating the coating film, in this order, wherein the coating film is formed from the radiation-sensitive composition for an insulating film of a display device according to claim 1 or 2 . 8. The method for forming an insulating film for a display device according to claim 7 , wherein the substrate includes an organic electroluminescence element. 9. The method for forming an insulating film for a display device according to claim 7 , wherein the heating is carried out at a temperature in the range of 60° C. or more and 120° C. or less .