Photocurable composition for forming a microcoating layer, microcoating layer, display device, and method for manufacturing the same.

Abstract

To provide a photocurable composition for forming a microcoating layer capable of obtaining a cured film having a high tensile elastic modulus, exhibiting a high elongation at break, and having excellent adhesion. 【Solution means】A photocurable composition for forming a microcoating layer disposed in a curved region connecting a display unit having a pixel array layer and a driving unit for driving the pixel array layer contains an N-substituted (meth)acrylamide, a compound represented by formula (1), and a radical polymerization initiator. In formula (1), R 1 and R 2 are each independently a hydrogen atom or a methyl group. R 3 is an alkanediyl group having 2 to 6 carbon atoms. n is an integer of 2 to 15. CH2=CR 1 -CO-O-(R 3 -O) n -CO-CR 2 =CH2…(1)

Description

Technical Field

[0001] The present invention relates to a photocurable composition for forming a microcoating layer, a microcoating layer, and a display device and a manufacturing method thereof.

Background Art

[0002] Various display devices such as organic electroluminescence (organic EL) display devices and liquid crystal display devices are widely used as touch panel-type devices typified by smartphones and tablet PCs, and multi-monitors installed by connecting multiple units. Further, in display devices, an attempt has been made to reduce the frame width in order to make the display area and the movable area wider. As one method for reducing the frame width of a display device, conventionally, in a flexible display mainly using a resin film as a base material, a drive unit that is usually arranged on the outer peripheral portion of the display area has been tried to be arranged on the back side of the display area (for example, see Patent Document 1 and Patent Document 2).

[0003] Patent Documents 1 and 2 disclose a liquid crystal panel including a display area provided with a pixel array layer and a drive unit connected to the pixel array layer via wiring, and curving a region connecting the display area and the drive unit to arrange the drive unit on the back side of the display area. In such a drive unit folded-back type display device, a microcoating layer (resin layer in Patent Document 2) is provided on the outer surface of the curved region connecting the display area and the drive unit, and the wiring arranged in the curved region is protected from the outside by the microcoating layer, and the stress applied to the curved region is relaxed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When manufacturing a display device in which a driving unit is disposed on the back side of a display area, first, a display unit having a pixel array layer and a driving unit of the pixel array layer are arranged side by side horizontally in a separated state, and after forming a microcoating layer between the display unit and the driving unit, the driving unit is disposed on the back side of the display unit by bending a region including the microcoating layer. Therefore, the microcoating layer is required to have physical properties that can withstand bending when the driving unit is disposed on the back side of the display unit. Specifically, it is required to have a high tensile elastic modulus, exhibit high elongation at break, and have excellent adhesion to the substrate.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a photocurable composition for forming a microcoating layer capable of obtaining a cured film having a high tensile elastic modulus, exhibiting high elongation at break, and having excellent adhesion. Another object is to provide a display device capable of achieving a narrow border while suppressing a decrease in product yield.

Means for Solving the Problems

[0007] According to the present invention, there are provided the following photocurable composition for forming a microcoating layer, a microcoating layer, a display device, and a method for manufacturing a display device.

[0008] 〔1〕 A photocurable composition for forming a microcoating layer disposed on an outer surface of a bending region connecting a display unit having a pixel array layer and a driving unit for driving the pixel array layer, the composition comprising an N-substituted (meth)acrylamide and the following formula (1): CH2=CR 1 -CO-O-(R 3 -O) n -CO-CR 2 =CH2…(1) (In formula (1), R 1 and R 2 are each independently a hydrogen atom or a methyl group. R 3is an alkandiyl group having 2 to 6 carbon atoms. n is an integer of 2 to 15. A plurality of Rs in the formula 3 are the same or different. ) A photocurable composition for forming a microcoating layer, containing a compound represented by and a radical polymerization initiator.

[0009] 〔2〕 The photocurable composition for forming a microcoating layer according to 〔1〕 above, wherein n in the above formula (1) is 4 or more. 〔3〕 The photocurable composition for forming a microcoating layer according to 〔1〕 or 〔2〕 above, further containing a (meth) acrylate compound having a phosphate group. 〔4〕 The photocurable composition for forming a microcoating layer according to 〔3〕 above, wherein the content of the (meth) acrylate compound having a phosphate group is 1 to 20 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds in the composition. 〔5〕 The photocurable composition for forming a microcoating layer according to any one of 〔1〕 to 〔4〕 above, wherein the content of the N-substituted (meth) acrylamide is 20 to 80 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds in the composition. 〔6〕 The photocurable composition for forming a microcoating layer according to any one of 〔1〕 to 〔5〕 above, wherein the content of the compound represented by the above formula (1) is 5 to 60 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds in the composition. 〔7〕 The photocurable composition for forming a microcoating layer according to any one of 〔1〕 to 〔6〕 above, wherein the content of the radical polymerization initiator is 0.2 to 15 parts by mass with respect to 100 parts by mass of the total amount of the polymerizable compounds in the composition. 〔8〕 The photocurable composition for forming a microcoating layer according to any one of 〔1〕 to 〔7〕 above, having a viscosity of 1.0 to 35.0 mPa·s measured under the conditions of 25 °C and 20 rpm using an E-type viscometer. 〔9〕 Irradiance 1000 mW / cm 2 and integrated light quantity 1000 mJ / cm 2A photocurable composition for forming a microcoating layer according to any one of [1] to [8] above, wherein the tensile modulus of a cured film with a thickness of 50 μm obtained by irradiating the photocurable composition with ultraviolet light of a wavelength of 395 nm under the conditions is 0.8 GPa or more.

[10] Illuminance 1000mW / cm 2 Furthermore, the integrated light intensity is 1000 mJ / cm². 2 A photocurable composition for forming a microcoating layer according to any one of [1] to [9] above, wherein the elongation at break of a cured film with a thickness of 50 μm obtained by irradiating the photocurable composition with ultraviolet light of a wavelength of 395 nm under the conditions is 20% or more.

[0010]

[11] A microcoating layer obtained by curing a photocurable composition for forming a microcoating layer as described in any of [1] to

[10] above.

[12] A display device comprising: a display unit having a pixel array layer; a drive unit for driving the pixel array layer; and a curved region connecting the display unit and the drive unit, wherein the curved region comprises a microcoating layer formed of a photocurable composition for forming a microcoating layer according to any one of [1] to

[10] above.

[13] A method for manufacturing a display device comprising a display unit having a pixel array layer and a drive unit for driving the pixel array layer, comprising the steps of: arranging the display unit and the drive unit side by side in the horizontal direction while spaced apart; applying a photocurable composition for forming a microcoating layer according to any one of [1] to

[10] above onto a substrate in a region including the space between the display unit and the drive unit; obtaining a microcoating layer by curing the photocurable composition for forming a microcoating layer on the substrate by irradiating it with radiation; and forming a curved region connecting the display unit and the drive unit by curving the region including the microcoating layer.

[14] A method for manufacturing a display device according to

[13] , wherein the photocurable composition for forming the microcoating layer is applied by inkjet coating. [Effects of the Invention]

[0011] According to the present invention, a microcoating layer with high tensile modulus, high elongation at break, and excellent adhesion can be obtained. Furthermore, by using a display device equipped with this microcoating layer, it is possible to narrow the bezel of the display panel while suppressing a decrease in the product yield rate. [Brief explanation of the drawing]

[0012] [Figure 1] A diagram showing the schematic configuration of the display device before the drive unit is placed on the back of the display unit. [Figure 2] This diagram shows a schematic configuration of a display device with the drive unit located on the back of the display unit. [Figure 3] Enlarged cross-sectional view of the portion including the curved area. [Modes for carrying out the invention]

[0013] The following describes in detail matters related to the embodiments. In this specification, numerical ranges indicated using "~" include the numbers indicated before and after "~" as the lower and upper limits, respectively.

[0014] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may also include a linear structure or an alicyclic hydrocarbon structure as part of it. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "Polymerizable compound" means a compound that has a polymerizable group that exhibits polymerizability upon irradiation with radiation.

[0015] 《Photocurable composition》 The photocurable composition disclosed herein (hereinafter also referred to as "this composition") is a composition for forming a microcoating layer provided on a display device. The microcoating layer is a resin layer provided on a curved portion of a display device (preferably a flexible display) that includes wiring extending from the display portion to the outside, and protects the wiring. In various display devices such as smartphones and tablet PCs, the bezel of the display device can be narrowed by placing the drive unit, which is normally located on the outer periphery of the display portion, on the back of the display portion.

[0016] This composition contains the following components (A), (B), and (C). Component (A): N-substituted (meth)acrylamide Component (B): Compound represented by the following formula (1) CH2=CR 1 -CO-O-(R 3 -O) n -CO-CR 2 =CH2…(1) (In formula (1), R 1and R 2 These are, independently of each other, a hydrogen atom or a methyl group. 3 R is an alkanediyl group having 2 to 6 carbon atoms. n is an integer from 2 to 15. Multiple R in the formula 3 They are either the same or different. Component (C): Radical polymerization initiator

[0017] The N-substituted (meth)acrylamide and the compound represented by formula (1) contained in this composition are polymerizable compounds that polymerize when light is applied in the presence of a radical polymerization initiator, due to the presence of an ethylenically unsaturated group (more specifically, a (meth)acryloyl group). Below, each component contained in this composition, and other components that may be added as needed, will be described in detail, along with the physical properties of this composition. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0018] <Component (A): N-substituted (meth)acrylamide> N-substituted (meth)acrylamide is (meth)acrylamide (CH2=CR 4 -CO-NH2, R 4 It has a substructure in which at least one hydrogen atom bonded to a nitrogen atom in a hydrogen atom or methyl group is removed, and an organic group is bonded to that nitrogen atom. Specific examples of N-substituted (meth)acrylamides include compounds represented by the following formula (2). CH2=CR 4 -CO-N(R 5 )(R 6 ) …(2) (In formula (2), R 4 R is a hydrogen atom or a methyl group. 5 and R 6 R 5 is a monovalent organic group, R 6 is a hydrogen atom or a monovalent organic group, or R 5 and R 6 When they are combined with each other, R 5 and R 6This represents a nitrogen-containing heterocyclic structure formed by the nitrogen atom to which it is bonded.

[0019] In equation (2) above, R 5 or R 6 The monovalent organic group represented by is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, with -O-, -S-, -CO-, -COO-, and -NR between the carbon-carbon bonds in the hydrocarbon group. 7 - or -CO-NR 7 - Groups containing (however, R 7 Examples include hydrogen atoms or monovalent organic groups having 1 to 20 carbon atoms. 7 Examples of monovalent organic groups having 1 to 20 carbon atoms represented by this formula include monovalent substituted or unsubstituted hydrocarbon groups having 1 to 10 carbon atoms, and the carbon-carbon bonds in such hydrocarbon groups containing -O-, -S-, -CO-, -COO-, and -NR. 7 - or -CO-NR 7 -Examples of groups including R 5 or R 6 When a monovalent organic group represented by has substituents, examples of such substituents include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.), hydroxyl groups, thiol groups, amino groups, carboxyl groups, and the like.

[0020] R 5 and R 6 When they are combined with each other, R 5 and R 6 The nitrogen-containing heterocyclic structure formed together with the bonded nitrogen atom is preferably an aliphatic ring structure, and more preferably a saturated aliphatic ring structure. Specific examples include pyrimidine ring structures, pyridazine ring structures, and morpholine ring structures. The heterocyclic structure constituting the nitrogen-containing heterocyclic structure may have substituents. Examples of such substituents include C1-C3 alkyl groups, C1-C3 alkoxy groups, hydroxyl groups, thiol groups, carboxyl groups, and amino groups.

[0021] In terms of having a high tensile modulus and excellent adhesion to the substrate, R 5 and R 6Each of these is either an alkyl group or R 5 and R 6 It is a nitrogen-containing heterocyclic structure formed together with the nitrogen atom to which it is bonded, or R 5 and R 6 It is preferable that at least one of them has a secondary amino group or a tertiary amino group.

[0022] Specific examples of N-substituted (meth)acrylamides include N-1 substituted (meth)acrylamides in which one of the two hydrogen atoms bonded to the nitrogen atom of (meth)acrylamide is substituted, N,N-2 substituted (meth)acrylamides in which both hydrogen atoms bonded to the nitrogen atom of (meth)acrylamide are substituted, and (meth)acrylamides having a nitrogen-containing heterocyclic structure.

[0023] Specific examples of these include N-1 substituted (meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-heptyl(meth)acrylamide, Nn-octyl(meth)acrylamide, N-tert-octyl(meth)acrylamide, N-lauryl(meth)acrylamide, N-stearyl(meth)acrylamide, N-oleyl(meth)acrylamide, and other N-alkyl(meth)acrylamides; N-alkoxyalkyl(meth)acrylamides such as N-methoxymethyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, N-propoxymethyl(meth)acrylamide, Nn-butoxymethyl(meth)acrylamide, and N-isobutoxymethyl(meth)acrylamide; Examples include N-hydroxyalkyl(meth)acrylamides such as N-hydroxyethyl(meth)acrylamide; and so on.

[0024] Examples of N,N-2 substituted (meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-methylethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N,N-diisobutyl(meth)acrylamide, N,N-dipentyl(meth)acrylamide, N,N-dihexyl(meth)acrylamide, N,N-diheptyl(meth)acrylamide, N,N-dioctyl(meth)acrylamide, and other N,N-dialkyl(meth)acrylamides; N-alkoxyalkyl-N-alkyl(meth)acrylamides such as N-methoxymethyl-N-methyl(meth)acrylamide, N-methoxyethyl-N-methyl(meth)acrylamide, and Nn-butoxymethyl-N-methyl(meth)acrylamide; Examples include N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide, N,N-dipropylaminopropyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, N,N-dibutylaminopropyl(meth)acrylamide, and other N,N-dialkylaminoalkyl(meth)acrylamides.

[0025] Examples of (meth)acrylamides having a nitrogen-containing heterocyclic structure include (meth)acryloylmorpholine, (meth)acryloylthiomorpholine, N-(meth)acryloyl-4-methylpiperidine, N-(meth)acryloylpiperidine, N-(meth)acryloyl-3,5-dimethylpiperidine, and N-(meth)acryloylpyrrolidine.

[0026] In terms of high curability, among the above, the N-substituted (meth)acrylamide is preferably at least one selected from the group consisting of N,N-dialkyl(meth)acrylamide, N-alkoxyalkyl(meth)acrylamide, N-hydroxyalkyl(meth)acrylamide, N,N-dialkylaminoalkyl(meth)acrylamide, and (meth)acrylamides having a nitrogen-containing heterocyclic structure, and more preferably at least one selected from the group consisting of N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, Nn-butoxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide. Furthermore, in terms of having an even higher tensile modulus and being able to form a cured film with excellent adhesion to the substrate, at least one selected from the group consisting of N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, and N,N-dimethylaminopropyl(meth)acrylamide is particularly preferred.

[0027] The content of N-substituted (meth)acrylamide in this composition is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. By setting the content of N-substituted (meth)acrylamide within the above range, a cured film with a sufficiently high tensile modulus and superior adhesion to the substrate (especially polyimide substrate) can be obtained. Furthermore, from the viewpoint of suppressing a decrease in the elongation at break of the cured film, the content of N-substituted (meth)acrylamide is preferably 80 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 70 parts by mass or less, and even more preferably 68 parts by mass or less, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0028] <Component (B): Compound represented by formula (1)> The compound represented by formula (1) above (hereinafter also referred to as "compound (B)") is a bifunctional polymerizable compound. From the viewpoint of ensuring the curability of the photocurable composition, it is preferable to increase the content of the monofunctional compound and increase the concentration of polymerizable groups in the photocurable composition. On the other hand, if the concentration of polymerizable groups in the photocurable composition is increased, the cured film obtained using the composition will not have sufficient elongation at break and its adhesion to the substrate will also decrease. Therefore, when such a cured film is applied to a microcoating layer, there is a concern that the microcoating layer may peel off or break from the substrate when the display unit and the drive unit are bent to form a curved region in order to place the drive unit on the back side of the display unit. In this regard, this composition contains a bifunctional compound (B) having two or more repeating alkylene units together with a monofunctional N-substituted (meth)acrylamide, thereby ensuring the curability of the photocurable composition while forming a cured film with excellent tensile modulus, elongation at break, and adhesion to the substrate. Furthermore, compound (B) can suppress the increase in viscosity of this composition.

[0029] In the above equation (1), R 3 The alkanediyl group having 2 to 6 carbon atoms, represented by R, may be linear or branched. 3 Specific examples include ethylene group, 1,3-propanediyl group, 1,2-propanediyl group, 2,2-propanediyl group, 1,4-butanediyl group, 1,3-butanediyl group, 1,2-butanediyl group, 1,5-pentanediyl group, 1,4-pentanediyl group, 1,6-hexanediyl group, 1,5-hexanediyl group, etc. From the viewpoint of obtaining a cured film with better elongation at break and ease of availability, R 3 Of these, an alkanediyl group having 2 or 3 carbon atoms is preferred.

[0030] In order to obtain a more superior elongation at break of the cured film obtained using this composition, n in formula (1) is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and even more preferably 7 or more. Furthermore, from the viewpoint of the availability of compound (B), n is preferably 14 or less.

[0031] Specific examples of compound (B) include diethylene glycol di(meth)acrylate (n=2 in formula (1) above), triethylene glycol di(meth)acrylate (n=3), polyethylene glycol #200 di(meth)acrylate (n≒4), polyethylene glycol #400 di(meth)acrylate (n≒9), polyethylene glycol #600 di(meth)acrylate (n≒14), dipropylene glycol di(meth)acrylate (n=2), tripropylene glycol di(meth)acrylate (n=3), polypropylene glycol #400 di(meth)acrylate (n≒7), polypropylene glycol #700 di(meth)acrylate (n≒12), and the like.

[0032] From the viewpoint of ensuring the elongation at break and reliability of the cured film obtained using this composition, the content of compound (B) in this composition is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. Furthermore, from the viewpoint of ensuring the tensile modulus and adhesion to the substrate of the cured film, the content of compound (B) 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, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0033] Furthermore, from the viewpoint of improving the elongation at break of the cured film, it is preferable that the composition contains a compound in formula (1) where n is 4 or more. From the viewpoint of sufficiently obtaining the effect of improving the elongation at break while maintaining a high degree of tensile modulus and adhesion of the cured film obtained using the composition, the content of the compound in formula (1) where n is 4 or more is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in the composition. Furthermore, from the viewpoint of ensuring a high tensile modulus and good adhesion of the cured film, the content of the compound in formula (1) where n is 4 or more 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, based on 100 parts by mass of the total amount of polymerizable compounds contained in the composition.

[0034] The total amount of N-substituted (meth)acrylamide and compound (B) in this composition is preferably 25 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 65 parts by mass or more, even more preferably 75 parts by mass or more, and even more preferably 80 parts by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0035] <Component (C): Radical polymerization initiator> The radical polymerization initiator is preferably a photoradical polymerization initiator that generates radicals in response to radiation and initiates polymerization. Examples of radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light, X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. The radical polymerization initiator to be included in this composition is not particularly limited, but examples include O-acyloxime compounds, acetophenone compounds, biimidazole compounds, and acylphosphine oxide compounds.

[0036] Examples of O-acyloxime compounds include 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethane-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime), 1-(9-ethyl-6-benzoyl-9H-carbazole-3-yl)-octan-1-oneoxime-O-acetate, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-ethane-1-oneoxime-O-benzoate, 1-[9-n-butyl-6-(2-ethylbenzoyl)-9H-carbazole-3-yl]-ethane-1-oneoxime-O-benzoate, and ethane-1 Examples include -[9-ethyl-6-(2-methyl-4-tetrahydrofuranylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime), ethanoone-1-[9-ethyl-6-(2-methyl-4-tetrahydropyranylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime), ethanoone-1-[9-ethyl-6-(2-methyl-5-tetrahydrofuranylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime), and ethanoone-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl}-9H-carbazole-3-yl]-1-(O-acetyloxime). Among O-acyloxime compounds, polymerization initiators having a carbazole skeleton in their molecule (for example, ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyloxime)) can be preferably used.

[0037] Examples of acetophenone compounds include α-aminoketone compounds and α-hydroxyketone compounds. Specific examples of these include α-aminoketone compounds such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)-butan-1-one, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-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-hydroxycyclohexylphenyl ketone.

[0038] Examples of biimidazole compounds include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, or 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0039] Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0040] From the viewpoint of ensuring good curability, the content of the radical polymerization initiator in this composition is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. Furthermore, the content of the radical polymerization initiator is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. By setting the content of the radical polymerization initiator to 15 parts by mass or less, it is possible to suppress the generation of outgassing from decomposition products while exhibiting good curability, and it is also possible to suppress the decrease in the tensile modulus of the cured film due to the radical polymerization initiator acting as a plasticizer component.

[0041] <Other ingredients> In addition to the N-substituted (meth)acrylamide, compound (B), and radical polymerization initiator described above, this composition may further contain components different from the N-substituted (meth)acrylamide, compound (B), and radical polymerization initiator (hereinafter also referred to as "other components"). Examples of other components include monofunctional polymerizable compounds different from N-substituted (meth)acrylamide (hereinafter also referred to as "monofunctional compound (D1)"), polyfunctional polymerizable compounds different from compound (B) (hereinafter also referred to as "polyfunctional compound (D2)"), surfactants, and the like.

[0042] • Monofunctional compound (D1) Monofunctional compound (D1) is a component copolymerizable with N-substituted (meth)acrylamide and compound (B), and can form a polymer together with N-substituted (meth)acrylamide and compound (B) upon irradiation with radiation. Monofunctional compound (D1) can be incorporated into this composition for purposes such as adjusting the viscosity of the composition, reinforcing the crosslinked structure, and adjusting various properties such as the elongation at break and adhesion to the substrate of the cured film.

[0043] As the monofunctional compound (D1), compounds having an ethylenically unsaturated group as a polymerizable group are preferably used. Specifically, examples include vinyl group-containing compounds, (meth)acryloyl group-containing compounds, aromatic vinyl compounds, etc. Among these, (meth)acrylate compounds are preferably used because of their copolymerizability with N-substituted (meth)acrylamide and compound (B), and because the viscosity of the composition can be adjusted relatively easily.

[0044] Specific examples of monofunctional compounds (D1) include alkyl (meth)acrylates, alicyclic (meth)acrylates, aromatic rings, alkoxyalkyl (meth)acrylates, amino (meth)acrylate compounds, hydroxyl (meth)acrylate compounds, phosphate (meth)acrylate compounds, urethane (meth)acrylate compounds, aromatic vinyl compounds, and the like.

[0045] Specific examples of the above compounds include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, n-undecyl methacrylate, n-lauryl methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, n-pentadecyl methacrylate, n-hexadecyl methacrylate, n-stearyl methacrylate, isostearyl methacrylate, n-nonadecyl methacrylate, and n-eicosyl methacrylate.

[0046] Examples of (meth)acrylic acid esters having an alicyclic structure include cyclohexyl (meth)acrylate, 2-methylcyclohexyl (meth)acrylate, and tricyclo(meth)acrylate [5.2.1.0 2,6 ] Decane-8-yl, (meth)acrylate tricyclo[5.2.1.0 2,5Examples include decane-8-yloxyethyl and isobornyl (meth)acrylate. Examples of (meth)acrylic acid esters having an aromatic ring structure include phenyl (meth)acrylate, benzyl (meth)acrylate, naphthylmethyl (meth)acrylate, naphthylethyl (meth)acrylate, phenoxyethyl (meth)acrylate, m-phenoxyphenylmethyl (meth)acrylate, and o-phenylphenoxyethyl (meth)acrylate.

[0047] Examples of (meth)acrylate alkoxyalkyl esters include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, n-propoxyethyl (meth)acrylate, n-butoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, ethoxybutyl (meth)acrylate, n-propoxybutyl (meth)acrylate, and n-butoxybutyl (meth)acrylate.

[0048] Examples of (meth)acrylate compounds having an amino group include dimethylaminomethyl (meth)acrylate, diethylaminomethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-(di-n-propylamino)ethyl (meth)acrylate, 2-dimethylaminopropyl (meth)acrylate, 2-diethylaminopropyl (meth)acrylate, 2-(di-n-propylamino)propyl (meth)acrylate, 3-dimethylaminopropyl (meth)acrylate, 3-diethylaminopropyl (meth)acrylate, and 3-(di-n-propylamino)propyl (meth)acrylate.

[0049] Examples of (meth)acrylate compounds having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0050] As (meth)acrylate compounds having a phosphate group, compounds are used in which one or more of the three hydroxyl groups in phosphoric acid (O=P(OH)3) are replaced with an organic group having a (meth)acryloyloxy group. Specific examples of (meth)acrylate compounds having a phosphate group include, for example, the Phosmer series from Unichemical (Phosmer-M, Phosmer-CL, Phosmer-PE, Phosmer-MH, Phosmer-PP); the KAYAMER series from Nippon Kayaku (e.g., KAYAMER PM-21, KAYAMER PM-2); PPME, PMR12, PPM-5P from Toho Chemical Industry; and the Light Ester series from Kyoeisha Chemical (e.g., Light Ester P-2M).

[0051] Examples of (meth)acrylate compounds having a urethane group include methylaminocarbonyloxyethylene (meth)acrylate, ethylaminocarbonyloxyethylene (meth)acrylate, propylaminocarbonyloxyethylene (meth)acrylate, butylaminocarbonyloxyethylene (meth)acrylate, pentylaminocarbonyloxyethylene (meth)acrylate, and hexylaminocarbonyloxyethylene (meth)acrylate. Examples of aromatic vinyl compounds include styrene, methylstyrene, α-methylstyrene, t-butoxystyrene, and vinylnaphthalene.

[0052] When a monofunctional compound (D1) is incorporated into this composition, the content of the monofunctional compound (D1) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, and most preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition (i.e., the total amount of N-substituted (meth)acrylamide, compound (B), monofunctional compound (D1), and polyfunctional compound (D2)). This is from the viewpoint of ensuring good adhesion of the cured film obtained from this composition to the substrate and maintaining high tensile modulus and elongation at break.

[0053] As the monofunctional compound (D1), at least one selected from the group consisting of alkyl (meth)acrylates and (meth)acrylate compounds having a phosphate group can be preferably used, as it can improve the elongation at break and adhesion of the cured film obtained from this composition.

[0054] If this composition further contains an alkyl (meth)acrylate, the elongation at break of the cured film obtained from this composition can be further improved. From the viewpoint of enhancing the effect of improving the elongation at break of the cured film, the alkyl (meth)acrylate blended into this composition preferably has an alkyl group having 6 or more carbon atoms, and more preferably has an alkyl group having 10 or more carbon atoms.

[0055] When an alkyl (meth)acrylate is incorporated into this composition, the amount of alkyl (meth)acrylate is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, per 100 parts by mass of the total amount of polymerizable compounds contained in this composition, from the viewpoint of sufficiently obtaining the effect of improving the elongation at break of the cured film obtained from this composition. Furthermore, from the viewpoint of ensuring the adhesion and tensile modulus of the cured film, the amount of alkyl (meth)acrylate is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0056] From the viewpoint of further improving the adhesion of the cured film obtained from this composition to the substrate, it is preferable that this composition further contains a (meth)acrylate compound having a phosphate group. When a (meth)acrylate compound having a phosphate group is blended into this composition, the content of the (meth)acrylate compound having a phosphate group is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of the total amount of polymerizable compounds contained in this composition. Furthermore, from the viewpoint of moderately lowering the viscosity of this composition and increasing the tensile modulus of the cured film obtained using this composition, the content of the (meth)acrylate compound having a phosphate group is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0057] On the other hand, when a (meth)acrylate compound having a urethane group is incorporated into this composition, the cured film (microcoating layer) is prone to deterioration under high temperature and high humidity, which can easily lead to a decrease in the reliability of the display device. In particular, the microcoating layer may be placed on the outermost layer of the display panel and may come into contact with the atmosphere, so it is required to maintain its performance under more severe conditions. From this viewpoint, it is preferable that the content of the (meth)acrylate compound having a urethane group in this composition be as low as possible. Specifically, the content of the (meth)acrylate compound having a urethane group is preferably 3 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, and most preferably 0.5 parts by mass or less, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition. Furthermore, it is particularly preferable that this composition does not contain a (meth)acrylate compound having a urethane group.

[0058] The total amount of N-substituted (meth)acrylamide, compound (B), alkyl (meth)acrylate, and (meth)acrylate compound having a phosphate group in this composition is preferably 75 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0059] ·Multifunctional compound (D2) The polyfunctional compound (D2), like the monofunctional compound (D1), is copolymerizable with N-substituted (meth)acrylamide and compound (B), and can form polymers together with N-substituted (meth)acrylamide and compound (B) upon irradiation. The polyfunctional compound (D2) can be incorporated into this composition for purposes such as adjusting the viscosity of the composition or reinforcing the crosslinked structure.

[0060] As the polyfunctional compound (D2), a compound having an ethylenically unsaturated group as a polymerizable group is preferably used. (Meth)acrylate compounds are preferably used as the polyfunctional compound (D2) because of their copolymerizability with N-substituted (meth)acrylamide and compound (B), and because the viscosity of this composition can be adjusted relatively easily.

[0061] Specific examples of polyfunctional compounds (D2) include difunctional (meth)acrylic acid esters and trifunctional or more (meth)acrylic acid esters. Examples of these include difunctional (meth)acrylic acid esters such as neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and 1,10-decanediol di(meth)acrylate.

[0062] Examples of trifunctional or more (meth)acrylic acid esters include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, tri(2-(meth)acryloyloxyethyl)phosphate, succinate Examples include acid-modified pentaerythritol tri(meth)acrylate, succinic acid-modified dipentaerythritol penta(meth)acrylate, carboxyl group-containing polybasic acid-modified (meth)acrylic oligomers, and polyfunctional urethane acrylate compounds obtained by reacting a compound having a linear alkylene group and an alicyclic structure and two or more isocyanate groups with a compound having one or more hydroxyl groups in the molecule and three, four, or five (meth)acryloyloxy groups.

[0063] From the viewpoint of ensuring the curability of the composition and suppressing a decrease in the elongation at break and adhesion of the cured film to the substrate, the content of the polyfunctional compound (D2) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the total amount of polymerizable compounds contained in the composition.

[0064] • Surfactants Surfactants can be used to further improve the applicability of this composition (specifically, by improving wetting spread and reducing uneven application). Examples of surfactants include fluorinated surfactants (including fluorinated nonionic surfactants), silicone surfactants, and nonionic surfactants.

[0065] Specific examples of surfactants include fluorine-based surfactants such as Megafac F-171, F-172, F-173, F-251, F-430, F-554, and F-563 (manufactured by DIC Corporation); Florard FC430 and FC431 (manufactured by Sumitomo 3M Corporation); Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106, and S-611 (manufactured by AGC Seimi Chemical Co., Ltd.); Polyflow No. 75 and No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.); FTX-218 (manufactured by Neos Co., Ltd.); and Ftop EF301, EF303, and EF352 (manufactured by Shin Akita Chemical Co., Ltd.).

[0066] Examples of silicone-based surfactants include the following product names: SH200-100cs, SH28PA, SH30PA, SH89PA, SH190, SH8400, SH193, SZ6032, SF8428, DC57, DC190, PAINTAD19, FZ-2101, FZ-77, FZ-2118, L-7001, L-7002 (manufactured by Toray Dow Corning); organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); BYK-300, BYK-306, BYK-310, BYK-330, BYK-333, BYK-335, BYK-341, BYK-344, BYK-370, BYK-340, BYK-345 (manufactured by BIC Chemie Japan).

[0067] Examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate.

[0068] When a surfactant is incorporated into this composition, the surfactant content is preferably 0.01 to 3 parts by mass, more preferably 0.02 to 2 parts by mass, and even more preferably 0.1 to 1.0 parts by mass, based on 100 parts by mass of the total amount of polymerizable compounds contained in this composition.

[0069] Other components, in addition to those mentioned above, include polymerization inhibitors, antioxidants, sensitizers, softeners, plasticizers, adhesion aids, and organic solvents. The proportions of these components are appropriately selected according to each component, within a range that does not impair the effects of this disclosure.

[0070] Organic solvents may be added to this composition for purposes such as dissolving each component. On the other hand, from the viewpoint of enabling the formation of a cured film (i.e., a microcoating layer) without heat treatment, it is preferable to minimize the amount of organic solvent used. Specifically, the content of organic solvents in this composition is preferably 0% by mass or more and 3% by mass or less, more preferably 0% by mass or more and 2% by mass or less, and particularly preferably substantially absent. Hereinafter, "substantially absent organic solvents" means that the amount of organic solvent contained in this composition is 1% by mass or less, preferably 0.5% by mass or less.

[0071] When an organic solvent is incorporated into this composition, it is preferable to use an organic solvent that can dissolve or disperse each component incorporated into this composition and does not react with each component. Specifically, examples include alcohols, ketones, esters, ethers, aromatic hydrocarbons, and amides.

[0072] Specific examples of these include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, γ-butyrolactone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and methyl-3-methoxypropionate; ethers such as polyoxyethylene lauryl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, and diethylene glycol methyl ethyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0073] <Preparation of photocurable compositions> This composition can be prepared by mixing N-substituted (meth)acrylamide, compound (B), a radical polymerization initiator, and other components as needed. The amount of polymerizable compounds in this composition (i.e., the total amount of N-substituted (meth)acrylamide, compound (B), monofunctional compound (D1), and polyfunctional compound (D2)) is preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 90 parts by mass or more, based on 100 parts by mass of the total amount of this composition, from the viewpoint of providing a photocurable composition with good sensitivity to radiation and forming a highly reliable cured film.

[0074] <Viscosity> The viscosity of this composition, as measured using an E-type viscometer at 25°C and 20 rpm, is preferably in the range of 1.0 to 35.0 mPa·s. When the viscosity of this composition is 35.0 mPa·s or less, the wettability and spreadability are good when the composition is applied to a substrate by inkjet coating, and uneven coating due to repellency, etc., can be suppressed. Furthermore, when the viscosity of this composition is 1.0 mPa·s or more, a sufficient film thickness can be ensured when the composition is applied to a substrate. This composition is suitable as a curable composition for inkjet coating.

[0075] From the viewpoint of obtaining a photocurable composition with excellent inkjet coating properties, the viscosity of this composition is more preferably 30.0 mPa·s or less, even more preferably 25.0 mPa·s or less, and even more preferably 22.0 mPa·s or less. Furthermore, from the viewpoint of stable inkjet ejection and ensuring sufficient film thickness, the viscosity of this composition is more preferably 2.0 mPa·s or more, even more preferably 5.0 mPa·s or more, and even more preferably 10.0 mPa·s or more. In this specification, the viscosity of the photocurable composition is a value measured in accordance with JIS K2283.

[0076] <Tensile modulus> By curing this composition, a cured film with a sufficiently high tensile modulus can be obtained. Specifically, when this composition is exposed to an illuminance of 1000 mW / cm²... 2 Furthermore, the integrated light intensity is 1000 mJ / cm². 2For a 50 μm thick cured film obtained by irradiation with ultraviolet light at a wavelength of 395 nm under the specified conditions, the tensile modulus measured at 23°C in accordance with the tensile test method based on JIS K6911 is preferably 0.8 GPa or higher. From the viewpoint of obtaining a microcoating layer with excellent bending resistance, the tensile modulus of the cured film measured under these conditions is more preferably 0.9 GPa or higher, and even more preferably 1.0 GPa or higher. Furthermore, the tensile modulus of the cured film measured under the above conditions is preferably 2.5 GPa or lower, and more preferably 2.0 GPa or lower. For details on the measurement method for the tensile modulus of the cured film, please refer to the method described in the examples below.

[0077] <Elongation at break> Furthermore, by curing this composition, a cured film with sufficiently high elongation at break can be obtained. Specifically, when this composition is subjected to an illuminance of 1000 mW / cm²... 2 Furthermore, the integrated light intensity is 1000 mJ / cm². 2 For a 50 μm thick cured film obtained by irradiation with ultraviolet light at a wavelength of 395 nm under the specified conditions, the elongation at break measured at 23°C in accordance with the tensile test method based on JIS K6911 is preferably 20% or more. From the viewpoint of obtaining a microcoating layer with excellent bending resistance, the elongation at break of the cured film measured under these conditions is more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more. Furthermore, from the viewpoint of ensuring the reliability of the device, the elongation at break of the cured film measured under the above conditions is preferably 180% or less, and more preferably 150% or less. Details of the measurement method for the elongation at break of the cured film will be described in the examples below.

[0078] Microcoating layer and display device The microcoating layer of this disclosure is formed from a photocurable composition prepared as described above. This composition makes it possible to obtain a cured film with excellent bending resistance and adhesion to a substrate (especially a resin substrate). Such a composition is suitable as a material for forming a microcoating layer that protects wiring from the outside in a curved region connecting the display unit of a display device and a drive unit located on the back side of the display unit, where wiring extending from the display unit to the drive unit is provided.

[0079] An embodiment of an organic EL display device incorporating a microcoating layer formed by this composition will be described with reference to Figures 1 to 3. Figure 1 shows the display device before the drive unit is placed on the back of the display unit, and Figure 2 shows the display device with the drive unit placed on the back of the display unit. Figure 3 is an enlarged cross-sectional view of the portion of Figure 2 that includes the curved region SD.

[0080] As shown in Figures 1 and 2, the display device 10 comprises a display unit 12 having a pixel array layer 11 and a drive unit 13 for driving the pixel array layer 11. The pixel array layer 11 is an organic EL layer in which thin-film transistors, electrode layers, planarization layers, transport layers, bank layers, organic light-emitting layers, encapsulation layers, etc., are stacked on a substrate 14. Since the pixel array layer 11 is a known organic EL layer, a detailed explanation is omitted here.

[0081] The substrate 14 is a flexible transparent resin film. Examples of resins that can form the substrate 14 include polyester, polyolefin, polystyrene, polyimide, polyamide, polyamideimide, polyetherimide, polyarylate, polyethersulfone, polysulfone, polyetheretherketone, polycarbonate, polyvinyl chloride, polyvinylidene chloride, and polyurethane. The substrate 14 may also be a glass substrate. In addition to the pixel array layer 11, the display unit 10 has an optical film, a polarizing plate, a cover glass, and the like laminated on it.

[0082] The drive unit 13 includes a driver IC 16 placed on the substrate 15 and controls the driving of the pixel array layer 11. The substrate 15 may be a flexible transparent resin film, and the drive unit 13 may have a chip-on-film structure. The drive unit 13 is connected to the pixel array layer 11 via wiring 17. The drive unit 13 displays an image on the display unit 12 by outputting a signal to the pixel array layer 11 based on a signal received from the circuit board 18.

[0083] The drive unit 13 is positioned in a non-display area SB on the substrate 14, spaced apart from the display unit 12. In the non-display area SB, a wiring area SC is provided between the display unit 12 and the drive unit 13, where the wiring 17 is arranged. Before the drive unit 13 is positioned on the back side of the display unit 12, the display unit 12 and the drive unit 13 are positioned horizontally side by side, separated by the wiring area SC (see Figure 1). A microcoating layer 19 is formed in the wiring area SC, covering the wiring 17. The microcoating layer 19 is formed by curing this composition. The microcoating layer 19 is positioned as the outermost layer of the wiring area SC so as to cover the entire wiring 17, and has a predetermined thickness (e.g., 10 to 150 μm).

[0084] To obtain the display device 10 shown in Figure 2, the substrate 14 is folded back at the wiring region SC (fold line LA in Figure 1) so that the drive unit 13 is positioned on the back side of the display unit 12. This forms a curved region SD on the display device 10 (see Figure 2). As shown in Figure 3, wiring 17 and a micro-coating layer 19 covering the surface of the wiring 17 are arranged in the curved region SD. With the curved region SD formed, the back surface 12a of the display unit 12 and the back surface 13a of the drive unit 13 face each other. In other words, in the display device 10, the display unit 12 is positioned on the front side of the display device 10 (the observer side of the display device 10), and the drive unit 13 is positioned on the back side of the display device 10. This makes it possible to narrow the bezel of the display device 10.

[0085] <Method for manufacturing a display device> Next, a method for manufacturing the display element of the present disclosure will be described. The display device of the present disclosure can be manufactured by a method comprising the following steps 1 to 4. Step 1: The process of arranging the display unit and the drive unit side by side horizontally, with space between them. Step 2: A step of applying the composition to the substrate in the area including the space between the display unit and the drive unit. Step 3: A step to obtain a microcoating layer by irradiating the composition on the substrate with radiation and curing it. Step 4: A step to form a curved region connecting the display unit and the drive unit by curving the region containing the microcoating layer.

[0086] In step 1, the method for arranging the display unit and the drive unit horizontally side by side while spacing them apart is not particularly limited and can be carried out according to known methods. In step 1, the display unit and the drive unit may be arranged on the same surface of the same substrate. Alternatively, the display unit and the drive unit may be arranged on different substrates, and the display unit and the drive unit may be arranged horizontally side by connecting the first substrate on which the display unit is arranged and the second substrate on which the drive unit is arranged directly or via a third substrate.

[0087] In step 2, examples of methods for applying the composition include spray coating, roll coating, spin coating, slit die coating, bar coating, and inkjet coating. Of these, the inkjet coating method is preferred in terms of throughput and thin film formation. In particular, the composition exhibits excellent curability despite its low viscosity, and the occurrence of uneven coating is suppressed, making it suitable for inkjet coating.

[0088] In step 3, the coating film formed in step 2 is irradiated with radiation to cure the coating film, thereby obtaining a cured film as a microcoating layer. Examples of radiation include charged particle beams such as ultraviolet light, far ultraviolet light, visible light, X-rays, and electron beams. Among these, ultraviolet light is preferred, and for example, ultraviolet light with a wavelength of 350 to 400 nm can be preferably used as the irradiation light. The radiation exposure dose is 100 to 3,000 J / m 2is preferred. From the viewpoint of sufficiently protecting the wiring, the thickness of the cured film is about 5 to 150 μm.

[0089] In Step 4, for a device including a display unit and a drive unit arranged side by side in the horizontal direction, by folding back the region including the microcoating layer (that is, the wiring region SC in FIG. 1), the drive unit is arranged on the back side of the display unit. As a result, the region connecting the display unit and the drive unit is folded back to form a curved region SD (see FIG. 2).

Example

[0090] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0091] 1. Preparation of photocurable composition The types and abbreviations of N-substituted (meth)acrylamide, compound (B), monofunctional compound (D1), polyfunctional compound (D2), radical polymerization initiator, and surfactant used in the preparation of the photocurable composition are shown below. <N-substituted (meth)acrylamide> A-1: Acryloylmorpholine [trade name: ACMO, manufactured by KJ Chemicals] A-2: N,N-Diethylacrylamide [trade name: DEAA, manufactured by KJ Chemicals] <Compound (B)> B-1: Polyethylene glycol #200 diacrylate [trade name: NK Ester A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.] B-2: Polypropylene glycol #400 diacrylate [trade name: NK Ester APG-400, manufactured by Shin-Nakamura Chemical Co., Ltd.] B-3: Polypropylene glycol #700 diacrylate [trade name: NK Ester APG-700, manufactured by Shin-Nakamura Chemical Co., Ltd.]

[0092] <Monofunctional compound (D1)> D1-1: Isostearyl acrylate [trade name: ISTA, manufactured by Osaka Organic Chemical Industry Co., Ltd.] D1-2: Isobornyl acrylate [Product name: IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.] D1-3: 1-Naphthylmethylacrylate [Product name: Light Acrylate 1-NMTA, manufactured by Kyoeisha Chemical Co., Ltd.] D1-4: Phosphate group-containing (meth)acrylate compound [Trade name PPM-5P, manufactured by Toho Chemical Co., Ltd.]

[0093] <Polyfunctional compound (D2)> D2-1: 1,9-nonanediol diacrylate [Product name: NK ester A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.] <Radical polymerization initiator> C-1: Omnirad 819 [Product name: Omnirad 819, manufactured by IGM Resin] C-2:TR-PBG-345 [Product name: TR-PBG-345, manufactured by Changzhou Strong Advanced Electronic Materials Co., Ltd.] <Surfactants> E-1: Silicone-based surfactant [Product name: BYK-333, manufactured by Bic Chemie Japan Co., Ltd.]

[0094] [Example 1] 70.0 parts by mass of compound (A-1), 30 parts by mass of compound (B-3), 1 part by mass of radical polymerization initiator (C-1), and 0.1 parts by mass of surfactant (E-1) were combined in a glass sample bottle and homogeneously mixed to obtain a mixture. This mixture was filtered using a PTFE filter to obtain a photocurable composition (R-1).

[0095] [Examples 2-7, Comparative Examples 1-3] The photocurable compositions (R-2) to (R-7) and (CR-1) to (CR-3) of Examples 2 to 7 and Comparative Examples 1 to 3 were prepared using the same method as in Example 1, except that the components used were of the types and amounts (parts by mass) shown in Table 1.

[0096] 2. Evaluation The viscosity of the photocurable compositions in Examples 1-7 and Comparative Examples 1-3 was measured. Furthermore, cured films were formed using the photocurable compositions in Examples 1-7 and Comparative Examples 1-3, and evaluated using the method described below. The evaluation results are shown in Table 1.

[0097] <Viscosity Measurement> The viscosity (mPa·s) of each photocurable composition was measured using an E-type viscometer (RE-85L, manufactured by Toki Sangyo Co., Ltd.) under the following conditions. [Measurement conditions] Cone rotor: Standard cone rotor (1°34' × R24) Measurement temperature: 25℃ Measurement range: M Rotation speed: 20 rpm

[0098] <Tensile modulus of elasticity, elongation at break> Each photocurable composition was applied to alkali-free glass using a spin coater so that the cured thickness was 50 μm. Next, each photocurable composition on the alkali-free glass was exposed to 395 nm ultraviolet light at an irradiance of 1,000 mJ / cm using an LED UV lamp. 2 , cumulative light intensity 1,000 mJ / cm 2 The film was cured by irradiation under the specified conditions. A UniJet E110Z HD (Type U395A-455, manufactured by Ushio Inc.) was used as the LED UV lamp. The resulting cured film was cut into strips 6 mm wide, and the tensile modulus of elasticity and the maximum elongation at break (elongation at break) of the cured film at 23°C were measured using the tensile test method based on JIS K6911 at a test length of 25 mm.

[0099] <Adhesion> A polyimide film (trade name Kapton®, manufactured by Toray DuPont) was attached to a silicon wafer, and each photocurable composition was coated using a spin coater to achieve a cured thickness of 10 μm. Next, each photocurable composition on the polyimide film was exposed to 395 nm ultraviolet light at a rate of 1,000 mJ / cm² using an LED UV lamp. 2The material was cured by irradiation with the specified irradiation dose. The LED UV lamp used was a UniJet E110Z HD (Type U395A-455, manufactured by Ushio Inc.). The obtained cured film was cross-cut into 1mm x 1mm squares (grid pattern) to form 100 regions surrounded by the cuts. Adhesive release tape was applied over the 100 regions, and then the tape was peeled off. The adhesion of the cured film to the polyimide film was evaluated by the number of regions from which the cured film peeled off when the tape was removed. A smaller number of peeled regions indicates better adhesion of the cured film to the polyimide film. Table 2 shows the number of peeled regions out of the 100 regions formed on the cured film. Scotch #610, 3M: 402N / 100mm (vertical direction) was used as the release tape.

[0100] [Table 1]

[0101] As shown in Table 1, the cured films obtained from the photocurable compositions (R-1) to (R-7) of Examples 1 to 7 exhibited high tensile modulus and elongation at break, as well as excellent adhesion to the substrate. In contrast, the cured film obtained from the photocurable composition (CR-1) of Comparative Example 1, which did not contain compound (B), did not exhibit sufficient elongation at break. Furthermore, the cured films obtained from the photocurable compositions (CR-2) and (CR-3) of Comparative Examples 2 and 3, which did not contain N-substituted (meth)acrylamide, exhibited low elongation at break and poor adhesion to the substrate. [Explanation of symbols]

[0102] 10...Display device, 11...Pixel array layer, 12...Display unit, 13...Drive unit, 14...Substrate, 17...Wiring, 19...Microcoating layer, SB...Non-display area, SC...Wiring area, SD...Curved area

Claims

1. A photocurable composition for forming a microcoating layer disposed in a curved region connecting a display unit having a pixel array layer and a drive unit that drives the pixel array layer, N-substituted (meth)acrylamide and The following formula (1): CH ２ =CR １ -CO-O-(R ３ -O) ｎ -CO-CR ２ =CH ２ …(1) (In formula (1), R １ and R ２ are, independently of each other, a hydrogen atom or a methyl group. R ３ is an alkanediyl group having 2 to 6 carbon atoms. n is an integer of 2 to 15. A plurality of R ３ in the formula are the same or different.) Compounds represented by, Radical polymerization initiator and A photocurable composition for forming a microcoating layer, containing the following:

2. The photocurable composition for forming a microcoating layer according to claim 1, wherein n in formula (1) above is 4 or more.

3. The photocurable composition for forming a microcoating layer according to claim 1, further comprising a (meth)acrylate compound having a phosphate group.

4. The photocurable composition for forming a microcoating layer according to claim 3, wherein the content of the (meth)acrylate compound having a phosphate group is 1 to 20 parts by mass per 100 parts by mass of the total amount of polymerizable compounds in the composition.

5. The photocurable composition for forming a microcoating layer according to claim 1, wherein the content of the N-substituted (meth)acrylamide is 20 to 80 parts by mass per 100 parts by mass of the total amount of polymerizable compounds in the composition.

6. The photocurable composition for forming a microcoating layer according to claim 1, wherein the content of the compound represented by the above formula (1) is 5 to 60 parts by mass per 100 parts by mass of the total amount of polymerizable compounds in the composition.

7. The photocurable composition for forming a microcoating layer according to claim 1, wherein the content of the radical polymerization initiator is 0.2 to 15 parts by mass per 100 parts by mass of the total amount of polymerizable compounds in the composition.

8. The photocurable composition for forming a microcoating layer according to claim 1, wherein the viscosity measured using an E-type viscometer at 25°C and 20 rpm is 1.0 to 35.0 mPa·s.

9. Illuminance 1000mW / cm ２ Furthermore, the cumulative light intensity is 1000 mJ / cm². ２ The photocurable composition for forming a microcoating layer according to claim 1, wherein the tensile modulus of a cured film with a thickness of 50 μm obtained by irradiating the photocurable composition with ultraviolet light of a wavelength of 395 nm under the conditions is 0.8 GPa or more.

10. Illuminance 1000mW / cm ２ Furthermore, the cumulative light intensity is 1000 mJ / cm². ２ The photocurable composition for forming a microcoating layer according to claim 1, wherein the elongation at break of a cured film with a thickness of 50 μm obtained by irradiating the photocurable composition with ultraviolet light of a wavelength of 395 nm under the conditions is 20% or more.

11. A microcoating layer obtained by curing a photocurable composition for forming a microcoating layer according to any one of claims 1 to 10.

12. A display unit having a pixel array layer, A drive unit for driving the aforementioned pixel array layer, A curved region connecting the display unit and the drive unit, Equipped with, The curved region comprises a microcoating layer formed with a photocurable composition for forming a microcoating layer according to any one of claims 1 to 10, wherein the curved region is a display device.

13. A method for manufacturing a display device comprising a display unit having a pixel array layer and a drive unit for driving the pixel array layer, The steps include: arranging the display unit and the drive unit side by side in the horizontal direction while keeping them separated from each other; A step of applying a photocurable composition for forming a microcoating layer according to any one of claims 1 to 10 onto a substrate in a region including the area between the display unit and the drive unit, A step of obtaining a microcoating layer by curing the photocurable composition for forming the microcoating layer on the substrate by irradiating it with radiation, A step of forming a curved region connecting the display unit and the drive unit by curving the region including the microcoating layer, A method for manufacturing a display device, including the method described above.

14. A method for manufacturing a display device according to claim 13, wherein the photocurable composition for forming the microcoating layer is applied by inkjet coating.

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