Peripheral sealant for display element

Abstract

The purpose of the present invention is to provide a peripheral sealant for a display element, the peripheral sealant making it possible to achieve a display element that has excellent impact resistance while having excellent curability with respect to long-wavelength light and excellent adhesion with respect to a metal. The present invention provides a peripheral sealant for a display element, the peripheral sealant containing a curable resin and a photopolymerization initiator. The curable resin contains a monofunctional polymerizable compound that has one polymerizable functional group in each molecule, and a polyfunctional polymerizable compound that has two or more polymerizable functional groups in each molecule, wherein the monofunctional polymerizable compound includes: a monofunctional polymerizable compound A which does not have a hydroxyl group, a carboxyl group, or a phosphate group, while having one polymerizable functional group and at least one structure that is selected from the group consisting of a phenyl group, an imide bond, and an alicyclic hydrocarbon skeleton in each molecule; and a monofunctional polymerizable compound B which has one polymerizable functional group and at least one structure that is selected from the group consisting of a hydroxyl group, a carboxy group, and a phosphate group in each molecule. The photopolymerization initiator includes a photopolymerization initiator that has an absorption coefficient of 75 mL / g∙cm or more at a wavelength of 450 nm.

Description

Peripheral sealing agent for display elements

[0001] The present invention relates to a peripheral sealing agent for display elements.

[0002] In recent years, liquid crystal displays and organic light-emitting diodes (OLEDs) have been widely used as display elements that are thin, lightweight, and have low power consumption. In such display elements, curable resin compositions are typically used for encapsulating the liquid crystal or organic light-emitting material layer.

[0003] For example, a liquid crystal display element is typically manufactured using a liquid crystal dropping method, known as the dropping method, which uses a peripheral sealant made of a curable resin composition, as disclosed in Patent Documents 1 and 2. In the dropping method, first, a peripheral sealant is applied to one of two electrode-equipped substrates to form a frame-shaped seal pattern. Next, while the peripheral sealant is still uncured, tiny droplets of liquid crystal are dropped into the frame of the seal pattern, and the other substrate is placed on top under vacuum to cure the peripheral sealant and produce a liquid crystal display element. Furthermore, the organic light-emitting material layer and electrodes that constitute an organic EL display element have the problem that their properties are easily degraded by moisture, oxygen, etc. As a method for isolating the organic light-emitting material layer and electrodes from the atmosphere, for example, Patent Documents 3 and 4 disclose a method in which the top of a laminate having organic light-emitting material layers arranged on a substrate is covered with a sealing member, and the periphery is surrounded by a sealing wall formed of a peripheral sealant made of a curable resin composition.

[0004] Japanese Patent Publication No. 2001-133794, International Publication No. 02 / 092718, Japanese Patent Publication No. 2007-59094, Japanese Patent Publication No. 2011-526629

[0005] Typically, peripheral sealants are cured by irradiating them with ultraviolet light, using a photocurable resin composition. However, this method has problems such as the sealant hardening due to the light from the alignment lamp, or the display element material degrading due to ultraviolet irradiation. Therefore, there has been a need for a peripheral sealant that can be sufficiently cured with long-wavelength light such as visible light. In recent years, mobile devices with display panels, such as smartphones and portable game consoles, have seen a trend towards narrower bezels for the display area from the perspective of miniaturization and improved design. On the other hand, with the spread of mobile devices, display elements are required to have impact resistance so that they do not break or peel off even when subjected to external impacts such as drops. Peripheral sealants also need to have the ability to mitigate impacts applied to the entire display element, even if the coating width is narrowed due to the narrow bezel. Furthermore, there has been a need for a peripheral sealant that can accommodate diverse designs and has excellent adhesion not only to non-metals such as glass but also to metals such as copper.

[0006] The present invention aims to provide a peripheral sealant for display elements that can obtain a display element with excellent curability to long-wavelength light, excellent adhesion to metals, and excellent impact resistance.

[0007] Disclosure 1 is a peripheral encapsulant for a display element containing a curable resin and a photopolymerization initiator, wherein the curable resin comprises a monofunctional polymerizable compound having one polymerizable functional group in one molecule and a polyfunctional polymerizable compound having two or more polymerizable functional groups in one molecule, wherein the monofunctional polymerizable compound does not have a hydroxyl group, a carboxyl group, or a phosphate group, and comprises monofunctional polymerizable compound A having one polymerizable functional group in one molecule and at least one structure selected from the group consisting of a phenyl group, an imide bond, and an alicyclic hydrocarbon skeleton, and monofunctional polymerizable compound B having one polymerizable functional group in one molecule and at least one structure selected from the group consisting of a hydroxyl group, a carboxyl group, and a phosphate group, and the photopolymerization initiator comprises a photopolymerization initiator having an extinction coefficient of 75 mL / g·cm or more at a wavelength of 450 nm. Disclosure 2 is a peripheral sealant for display elements of Disclosure 1, wherein the monofunctional polymerizable compound B has at least one structure selected from the group consisting of a carboxyl group and a phosphate group. Disclosure 3 is a peripheral sealant for display elements of Disclosure 1 or 2, wherein the polyfunctional polymerizable compound comprises a compound having two or more polymerizable functional groups and a linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms in one molecule. Disclosure 4 is a peripheral sealant for display elements of Disclosure 1, 2 or 3, wherein the polyfunctional polymerizable compound comprises a polyfunctional urethane (meth)acrylate having two or more (meth)acryloyl groups and a urethane bond in one molecule. Disclosure 5 is a peripheral sealant for display elements of Disclosure 1, 2 or 3, with a wavelength of 450 nm and an illuminance of 100 mW / cm ２ The peripheral sealant for display elements described in Disclosure 1, 2, 3, or 4 is characterized in that the cured product obtained by irradiating with light for 30 seconds exhibits a breaking elongation of 5.0% or more when subjected to a tensile test under the conditions of 25°C, a tensile speed of 10 mm / min, and a gripping distance of 25 mm. Disclosure 6 describes the peripheral sealant for display elements described in Disclosure 6 as being obtained by irradiating with light for 30 seconds, with a wavelength of 450 nm and an illuminance of 100 mW / cm². ２The peripheral sealant for display elements described in Disclosure 1, 2, 3, 4, or 5 is characterized in that the cured product obtained by irradiating with light for 30 seconds exhibits a breaking strength of 2.0 MPa or more when subjected to a tensile test under the conditions of 25°C, a tensile speed of 10 mm / min, and a gripping distance of 25 mm. Disclosure 7 describes the peripheral sealant for display elements described in Disclosure 7 as a product in which the peripheral sealant for display elements is applied to a copper substrate, and then a glass chip measuring 5 mm in length, 5 mm in width, and 0.6 mm in thickness is placed on top, and the irradiated with light at a wavelength of 450 nm and an illuminance of 100 mW / cm² is applied. ２ The peripheral sealant for display elements described in Disclosure 1, 2, 3, 4, 5, or 6 is characterized in that the laminate obtained by curing the peripheral sealant for display elements by irradiating it with light for 30 seconds exhibits a die shear strength of 5.0 MPa or more when subjected to a die shear test under the conditions of 25°C and a speed of 30 mm / min. The present invention is described in detail below.

[0008] The inventors investigated using a combination of a specific monofunctional polymerizable compound and a specific polyfunctional polymerizable compound as a curable resin in the peripheral encapsulant, and using a photopolymerization initiator whose absorption coefficient at a wavelength of 450 nm is above a specific value. As a result, they found that the obtained peripheral encapsulant for display elements exhibits excellent curability to long-wavelength light and adhesion to metals such as copper, and that it is possible to obtain a display element with excellent impact resistance, thus completing the present invention.

[0009] The peripheral encapsulant for display elements of the present invention contains a curable resin. The curable resin includes a monofunctional polymerizable compound having one polymerizable functional group in one molecule and a polyfunctional polymerizable compound having two or more polymerizable functional groups in one molecule.

[0010] Examples of polymerizable functional groups that the above monofunctional polymerizable compound and the above polyfunctional polymerizable compound may possess include radical polymerizable functional groups and cationic polymerizable functional groups. Among these, radical polymerizable functional groups are preferred. The above monofunctional polymerizable compound and the above polyfunctional polymerizable compound may have the same polymerizable functional group or may have different polymerizable functional groups. Furthermore, the monofunctional polymerizable compound A and monofunctional polymerizable compound B described later may have the same polymerizable functional group or may have different polymerizable functional groups. In this specification, hydroxyl groups, carboxyl groups, and phosphate groups are not treated as polymerizable functional groups. In this specification, the above "phosphate group" means a group that includes a P=O bond derived from phosphoric acid and one or two OH groups bonded to the phosphorus atom.

[0011] The above radical polymerizable functional group is preferably a group having a reactive carbon-carbon double bond, and more preferably a (meth)acryloyl group. In this specification, "(meth)acryloyl" means acryloyl or methacryloyl.

[0012] Examples of the cationic polymerizable functional groups mentioned above include epoxy groups, oxetanyl groups, vinyl ether groups, and the like.

[0013] The above monofunctional polymerizable compounds include monofunctional polymerizable compound A, which does not have a hydroxyl group, a carboxyl group, or a phosphate group, and has one of the above polymerizable functional groups and at least one structure selected from the group consisting of a phenyl group, an imide bond, and an alicyclic hydrocarbon skeleton in one molecule, and monofunctional polymerizable compound B, which has one of the above polymerizable functional groups and at least one structure selected from the group consisting of a hydroxyl group, a carboxyl group, and a phosphate group in one molecule. By including monofunctional polymerizable compound A and monofunctional polymerizable compound B in combination with the above polyfunctional polymerizable compound, the peripheral sealant for display elements of the present invention exhibits excellent adhesion to metals such as copper and excellent toughness, and is excellent in mitigating the impact applied to the entire display element.

[0014] The above monofunctional polymerizable compound A has no hydroxyl group, carboxyl group, and phosphate group, and has one of the above polymerizable functional groups and at least one structure selected from the group consisting of a phenyl group, an imide bond, and an alicyclic hydrocarbon skeleton in one molecule. By containing the above monofunctional polymerizable compound A having such a structure, the peripheral sealant for display elements of the present invention can increase the elongation at break and breaking strength of the cured product described later. Among them, the above monofunctional polymerizable compound A preferably has at least one structure selected from the group consisting of a phenyl group and an alicyclic hydrocarbon skeleton from the viewpoint of further increasing the elongation at break of the cured product described later, and preferably has an imide bond from the viewpoint of further increasing the breaking strength of the cured product described later.

[0015] Specific examples of the above monofunctional polymerizable compound A include, for example, phenoxyethyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, N-(meth)acryloyloxyethyl hexaphthalimide, phenoxypolyethylene glycol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate and the like. In this specification, the above "(meth)acrylate" means acrylate or methacrylate.

[0016] The preferable lower limit of the content of the above monofunctional polymerizable compound A in 100 parts by mass of the above curable resin is 10 parts by mass, and the preferable upper limit is 80 parts by mass. When the content of the above monofunctional polymerizable compound A in 100 parts by mass of the above curable resin is within this range, the obtained peripheral sealant for display elements will be excellent in the effect of alleviating the impact applied to the entire display element.The more preferable lower limit of the content of the above monofunctional polymerizable compound A in 100 parts by mass of the above curable resin is 30 parts by mass, and the more preferable upper limit is 60 parts by mass.

[0017] The monofunctional polymerizable compound B has at least one structure selected from the group consisting of a polymerizable functional group and a hydroxyl group, a carboxyl group, and a phosphate group in one molecule. By containing the monofunctional polymerizable compound B having such a structure, the peripheral sealant for a display element of the present invention can increase the adhesive force to a metal such as copper. Among them, from the viewpoint of further increasing the adhesive force to a metal such as copper, the monofunctional polymerizable compound B preferably has at least one structure selected from the group consisting of a carboxyl group and a phosphate group, and more preferably has a phosphate group.

[0018] Specific examples of the monofunctional polymerizable compound B include 2-hydroxyethyl (meth)acrylate acid phosphate, (meth)acryloyloxypolypropylene glycol phosphate, (meth)acryloyloxypolyethylene glycol phosphate, mono-2-((meth)acryloyloxy)ethyl phthalate, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, and the like.

[0019] The preferable lower limit of the content of the monofunctional polymerizable compound B in 100 parts by mass of the curable resin is 0.1 part by mass, and the preferable upper limit is 20 parts by mass. When the content of the monofunctional polymerizable compound B in 100 parts by mass of the curable resin is within this range, the obtained peripheral sealant for a display element will be excellent in the effect of mitigating the impact applied to the entire display element and the adhesiveness to a metal such as copper. The more preferable lower limit of the content of the monofunctional polymerizable compound B in 100 parts by mass of the curable resin is 1 part by mass, and the more preferable upper limit is 5 parts by mass.

[0020] The polyfunctional polymerizable compound has two or more of the polymerizable functional groups in one molecule. Among them, from the viewpoints of reactivity and adhesion to an adherend, etc., the number of the polymerizable functional groups that the polyfunctional polymerizable compound has in one molecule is preferably two or more and six or less.

[0021] The polyfunctional polymerizable compound preferably contains a compound having two or more polymerizable functional groups and a linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms in one molecule. The presence of the linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms in the polyfunctional polymerizable compound allows for greater elongation at break of the cured product, as described later. In particular, the preferred lower limit for the number of carbon atoms in the linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms is 5. Furthermore, from the viewpoint of ease of synthesis, the preferred upper limit for the number of carbon atoms in the linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms is 30. In addition, when the polyfunctional polymerizable compound has the linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms, the number of linear or branched chain hydrocarbon skeletons having 5 or more carbon atoms in one molecule of the polyfunctional polymerizable compound may be one or two or more.

[0022] The above polyfunctional polymerizable compounds preferably have at least one of a ring-opening structure of a lactone and a structure derived from a dibasic acid. Specifically, examples include the compound represented by the following formula (1) and the compound represented by the following formula (3).

[0023]

[0024] In formula (1), R １ R represents a hydrogen atom or a methyl group. ２ represents a group represented by the following formulas (2-1), (2-2), or (2-3), where Ar represents an optionally substituted arylene group, X represents the ring-opening structure of the lactone, n is between 1 and 5 (average value), and Ep represents a structure derived from an epoxy compound.

[0025]

[0026] In formulas (2-1) to (2-3), * and ** represent bond positions. In formula (2-2), a is an integer between 1 and 8, in formula (2-3), b is an integer between 1 and 8, c is an integer between 1 and 3, and d is an integer between 1 and 8. In formulas (2-1) and (2-3), of the bond positions * and **, * is the bond position with the (meth)acryloyloxy group in formula (1).

[0027]

[0028] In formula (3), R ３ The first two Zs represent a hydrogen atom or a methyl group, Y represents a linear or branched hydrocarbon skeleton with 6 to 20 carbon atoms, and the two Zs each independently represent a structure containing an aromatic ring.

[0029] Furthermore, it is preferable that the above-mentioned polyfunctional polymerizable compound contains a polyfunctional urethane (meth)acrylate having two or more (meth)acryloyl groups and urethane bonds in one molecule. By containing the above-mentioned polyfunctional urethane (meth)acrylate, the peripheral encapsulant for display elements of the present invention can achieve greater elongation at break and tensile strength of the cured product, as described later. The above-mentioned polyfunctional polymerizable compound may consist only of the above-mentioned polyfunctional urethane (meth)acrylate.

[0030] The number of urethane bonds in one molecule of the above-mentioned polyfunctional urethane (meth)acrylate may be one or two or more.

[0031] The above-mentioned polyfunctional urethane (meth)acrylate can be obtained, for example, by reacting a polyfunctional isocyanate compound having two or more isocyanate groups in one molecule with a (meth)acrylic acid derivative having a hydroxyl group in the presence of a catalytic amount of a tin-based compound.

[0032] Examples of the above-mentioned polyfunctional isocyanate compounds include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tollidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatephenyl)thiophosphate, tetramethylxylylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0033] Furthermore, as the polyfunctional isocyanate compound, a chain-extended polyfunctional isocyanate compound obtained by the reaction of a polyol with an excess of the polyfunctional isocyanate compound can also be used. Examples of the polyol include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate diol, polyether diol, polyester diol, and polycaprolactone diol.

[0034] Examples of (meth)acrylic acid derivatives having a hydroxyl group include hydroxyalkyl (meth)acrylate, mono(meth)acrylate of a dihydric alcohol, mono(meth)acrylate or di(meth)acrylate of a trihydric alcohol, and epoxy (meth)acrylate. Examples of hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Examples of dihydric alcohol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol. Examples of trihydric alcohol include trimethylolethane, trimethylolpropane, and glycerin. Examples of epoxy (meth)acrylate include bisphenol A type epoxy (meth)acrylate.

[0035] In particular, the above-mentioned polyfunctional urethane (meth)acrylate is preferably an aliphatic polyfunctional urethane (meth)acrylate that does not have an aromatic ring.

[0036] Examples of commercially available polyfunctional urethane (meth)acrylates include CN8881 and CN8888 (both manufactured by Sartmar).

[0037] The preferred lower limit for the content of the polyfunctional polymerizable compound in 100 parts by mass of the curable resin is 1 part by mass, and the preferred upper limit is 80 parts by mass. Having the content of the polyfunctional polymerizable compound in 100 parts by mass of the curable resin within this range results in the resulting peripheral sealant for the display element having superior effect in mitigating the impact applied to the entire display element. A more preferred lower limit for the content of the polyfunctional polymerizable compound in 100 parts by mass of the curable resin is 20 parts by mass, and a more preferred upper limit is 60 parts by mass.

[0038] The preferred lower limit for the total content of the curable resin in 100 parts by mass of the peripheral sealant for display elements of the present invention is 90 parts by mass, and the preferred upper limit is 99.5 parts by mass. Having the total content of the curable resin within this range results in a peripheral sealant for display elements with superior curability and adhesion. A more preferred lower limit for the total content of the curable resin is 95 parts by mass, and a more preferred upper limit is 99 parts by mass.

[0039] The peripheral encapsulant for display elements of the present invention contains a photopolymerization initiator. The photopolymerization initiator contains a photopolymerization initiator (hereinafter also referred to as "the photopolymerization initiator according to the present invention") having an absorption coefficient of 75 mL / g·cm or more at a wavelength of 450 nm. By containing the photopolymerization initiator according to the present invention, the peripheral encapsulant for display elements of the present invention exhibits excellent curability to long-wavelength light. The preferred lower limit of the absorption coefficient of the photopolymerization initiator according to the present invention at a wavelength of 450 nm is 100 mL / g·cm, and the more preferred lower limit is 1000 mL / g·cm. Furthermore, there is no particularly preferred upper limit for the absorption coefficient of the photopolymerization initiator according to the present invention at a wavelength of 450 nm, but the practical upper limit is 5000 mL / g·cm. The above absorption coefficient can be measured using a spectrophotometer after dissolving the compound to be measured in a solvent to a concentration of 0.1 mg / mL. The above solvent is not particularly limited as long as it can dissolve the compound to be measured and does not absorb at the absorption wavelength to be measured, for example, acetonitrile, methanol, etc.

[0040] As the photopolymerization initiator according to the present invention, a photo radical polymerization initiator, a photo cationic polymerization initiator, etc. are used, and those having an absorption coefficient at a wavelength of 450 nm of 75 mL / g·cm or more are selected according to the type of the above curable resin.

[0041] As the photopolymerization initiator according to the present invention, for example, compounds represented by the following formula (4) and having an absorption coefficient at a wavelength of 450 nm of 75 mL / g·cm or more are included.

[0042]

[0043] In formula (4), R ４ are each independently an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aralkyl group, a heterocyclic group, which may have an ether bond or an amide bond, or an aryl group which may have an ether bond or an amide bond, and the alkyl group having 1 to 20 carbon atoms, the cycloalkyl group, the aralkyl group, the heterocyclic group, and the aryl group may have a polar group. In formula (4), R ５ are each independently an alkyl group having 1 to \alpha carbon atoms, a cycloalkyl group, an aralkyl group, a heterocyclic group, which may have an ether bond or an amide bond, or an aryl group which may have an ether bond or an amide bond, and the alkyl group having 1 to 20 carbon atoms, the cycloalkyl group, the aralkyl group, the heterocyclic group, and the aryl group may have a polar group. In formula (4), R ６ are each independently an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, an aralkyl group, a heterocyclic group, which may have an ether bond or an amide bond, or an aryl group which may have an ether bond or an amide bond, and the alkyl group having 1 to 20 carbon atoms, the cycloalkyl group, the aralkyl group, the heterocyclic group, and the aryl group may have a polar group. In formula (4), R ７ is a bond, a structure having an arylene group, or a structure having a heteroarylene group.

[0044] R in the above formula (4) ４ It should be noted that in the above translation, the symbol "\alpha" in the original text should be "20", which may be a typo in the original. If this is not a typo, it needs to be further confirmed according to the specific situation.When is an alkyl group having 1 to 20 carbon atoms, the alkyl group is preferably a methyl group or an ethyl group. ４ When R is the above-mentioned cycloalkyl group, examples of the cycloalkyl group include a cyclohexyl group, a cyclobutyl group, and the like. ４ When R is the above-mentioned aralkyl group, examples of such aralkyl groups include phenylmethyl group, 2-naphthylmethyl group, etc. In formula (4) above, R ４ When is the heterocyclic group described above, examples of such heterocyclic groups include the 2-benzofuranyl group. In formula (4) above, R ４ When R is the above-mentioned aryl group, examples of the aryl group include a phenyl group, a 1-naphthyl group, etc. Among these, the phenyl group is preferred. In formula (4) above, R ４ If the above polar group is present, examples of the polar group include a hydroxyl group, a carboxyl group, an amino group, etc. Among these, a carboxyl group is preferred. For example, R in formula (4) above ４ In the case where is an alkyl group having 1 to 20 carbon atoms, the case in which the polar group has a carboxyl group is HO-C(=O)-R ８ - represents a group (R ８ This refers to cases where the group is an alkylene group having 1 to 20 carbon atoms, such as a carboxymethyl group or a 2-carboxyethyl group.

[0045] In the above formula (4), R ５ When R is an alkyl group having 1 to 20 carbon atoms, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a 2-ethylhexyl group, etc. Among these, a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group are preferred. In formula (4) above, R ５ When is the above cycloalkyl group, examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, etc. The above cycloalkyl group may have an alkyl group having 1 to 20 carbon atoms. In formula (4) above, R ５ When R is the above-mentioned aralkyl group, examples of the aralkyl group include a phenylmethyl group.５ When is the heterocyclic group described above, examples of such heterocyclic groups include the 2-benzothiophenyl group. In formula (4) above, R ５ When R is the above-mentioned aryl group, examples of the aryl group include a phenyl group. ５ If the above polar group is present, examples of the polar group include a hydroxyl group, a carboxyl group, an amino group, etc. Among these, a carboxyl group is preferred. For example, R in formula (4) above ５ In the case where is an alkyl group having 1 to 20 carbon atoms, the case in which the polar group has a carboxyl group is HO-C(=O)-R ８ - represents a group (R ８ This refers to cases where the group is an alkylene group having 1 to 20 carbon atoms, such as a carboxymethyl group or a 2-carboxyethyl group.

[0046] In the above formula (4), R ６ When is an alkyl group having 1 to 20 carbon atoms, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a 2-ethylhexyl group, etc. Among these, a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group are preferred. The alkyl group may also have an aryl group. In formula (4) above, R ６ When R is the above cycloalkyl group, examples of the cycloalkyl group include a cyclohexyl group. ６ When R is the above-mentioned aralkyl group, examples of the aralkyl group include the 2-naphthylmethyl group. ６ When is the above heterocyclic group, examples of such heterocyclic groups include the 2-thienyl group. In formula (4) above, R ６ When R is the above-mentioned aryl group, examples of the aryl group include a phenyl group. ６ If the above polar group is present, examples of the polar group include a hydroxyl group, a carboxyl group, an amino group, etc. Among these, a carboxyl group is preferred. For example, R in formula (4) above ６In the case where is an alkyl group having 1 to 20 carbon atoms, the case in which the polar group has a carboxyl group is HO-C(=O)-R ８ - represents a group (R ８ This refers to cases where the group is an alkylene group having 1 to 20 carbon atoms, such as a carboxymethyl group or a 2-carboxyethyl group.

[0047] In the above formula (4), R ７ When the above structure has an arylene group, examples of the arylene group include a 1,3-phenylene group, a 1,4-phenylene group, a 1,4-naphthylene group, and the like. Specifically, examples of structures having the above arylene group include structures represented by the following formulas (5-1) to (5-5). In formula (4) above, R ７ When the structure has the above-mentioned heteroarylene group, examples of the heteroarylene group include a thienylene group, a furanylene group, a pyridylene group, and the like. Among these, the thienylene group is preferred. Specific examples of structures having the above-mentioned heteroarylene group include structures represented by the following formulas (6-1) to (6-6).

[0048]

[0049] In equations (5-1) to (5-5), * indicates the bonding position.

[0050]

[0051] In equations (6-1) to (6-6), * indicates the bonding position.

[0052] Examples of photopolymerization initiators according to the present invention include, for example, the compound represented by the following formula (7), the compound represented by the following formula (8), and bis(2,4-cyclopentadienyl)bis[2,6-difluoro-3-(1-pyryl)phenyl]titanium. Among these, the compound represented by the following formula (7) and the compound represented by the following formula (8) are preferred because they exhibit excellent reactivity to long-wavelength light and excellent stability under a yellow lamp.

[0053]

[0054]

[0055] The preferred lower limit for the content of the photopolymerization initiator according to the present invention per 100 parts by mass of the above-mentioned curable resin is 0.01 parts by mass, and the preferred upper limit is 5.0 parts by mass. By having the content of the photopolymerization initiator according to the present invention within this range, the resulting peripheral encapsulant for display elements exhibits superior curability and storage stability against long-wavelength light. A more preferred lower limit for the content of the photopolymerization initiator according to the present invention is 0.5 parts by mass, and a more preferred upper limit is 2.0 parts by mass.

[0056] The peripheral sealing agent for display elements of the present invention may further contain fillers for purposes such as viscosity adjustment, further improvement of adhesion through stress dispersion effect, and improvement of the coefficient of linear expansion.

[0057] Inorganic or organic fillers can be used as the above-mentioned fillers. Examples of inorganic fillers include silica, talc, glass beads, asbestos, gypsum, diatomaceous earth, smectite, bentonite, montmorillonite, sericite, activated clay, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, calcium carbonate, magnesium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum nitride, silicon nitride, barium sulfate, and calcium silicate. Examples of organic fillers include polyester microparticles, polyurethane microparticles, vinyl polymer microparticles, and (meth)acrylic polymer microparticles.

[0058] The peripheral sealant for display elements of the present invention may further contain a silane coupling agent. The silane coupling agent mainly serves as an adhesive aid for further improving the adhesion between the peripheral sealant for display elements and a substrate or the like.

[0059] Suitable silane coupling agents include, for example, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-isocyanatetopropyltrimethoxysilane.

[0060] The peripheral sealing agent for display elements of the present invention may further contain, if necessary, additives such as a thermosetting agent, a curing accelerator, a light-shielding agent, a stress-relaxing agent, a reactive diluent, a thixotrope, a spacer, an antifoaming agent, a leveling agent, or a polymerization inhibitor.

[0061] Methods for manufacturing the peripheral encapsulant for display elements of the present invention include, for example, a method of mixing a curable resin, a photopolymerization initiator, and additives such as fillers and silane coupling agents as needed, using a mixer such as a homodisperser, homomixer, universal mixer, planetary mixer, kneader, or three-roll mixer.

[0062] The peripheral sealing agent for display elements of the present invention has a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ For a cured product obtained by irradiating it with light for 30 seconds, a preferred lower limit for the elongation at break (hereinafter simply referred to as "elongation at break of cured product") when a tensile test is performed under the conditions of 25°C, a tensile speed of 10 mm / min, and a grip distance of 25 mm is used. An elongation at break of 5.0% or higher results in a more superior effect of the resulting peripheral sealant for display elements in mitigating the impact applied to the entire display element. A more preferred lower limit for the elongation at break of the cured product is 10.0%. While there is no particularly preferred upper limit for the elongation at break of the cured product, the practical upper limit is 1000%. The elongation at break of the cured product and the tensile strength of the cured product described later were measured using an LED lamp with a wavelength of 450 nm and an illuminance of 100 mW / cm². ２ The hardened material, measuring 45 mm in length, 5 mm in width, and 0.5 mm in thickness, obtained by irradiating it with light for 30 seconds, can be measured by performing a tensile test on a tensile testing machine under the conditions of 25°C, a tensile speed of 10 mm / min, and a grip distance of 25 mm. Examples of the tensile testing machine include the Autograph AG-Xplus (manufactured by Shimadzu Corporation).

[0063] The peripheral sealing agent for display elements of the present invention has a wavelength of 450 nm and an illuminance of 100 mW / cm. ２For a cured product obtained by irradiating it with light for 30 seconds, the preferred lower limit of the breaking strength (hereinafter also simply referred to as "breaking strength of the cured product") when a tensile test is performed under the conditions of 25°C, a tensile speed of 10 mm / min, and a grip distance of 25 mm is 2.0 MPa. A breaking strength of 2.0 MPa or higher for the cured product results in a more superior effect of the peripheral sealant for display elements in mitigating the impact applied to the entire display element. A more preferred lower limit for the breaking strength of the cured product is 5.0 MPa, and an even more preferred lower limit is 10.0 MPa. Furthermore, there is no particularly preferred upper limit for the breaking strength of the cured product, but the practical upper limit is 100 MPa.

[0064] The peripheral sealing agent for display elements of the present invention is applied to a copper substrate, and then a glass chip measuring 5 mm in length, 5 mm in width, and 0.6 mm in thickness is placed on top, with a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ The laminate obtained by curing the peripheral sealant for the display element by irradiating it with light for 30 seconds has a preferred lower limit of die shear strength of 5.0 MPa when a die shear test is performed under the conditions of 25°C and a speed of 30 mm / min. A die shear strength of 5.0 MPa or higher makes the resulting peripheral sealant for the display element suitable for use in bonding metals such as copper. A more preferred lower limit of die shear strength is 10.0 MPa. While there is no particularly preferred upper limit for die shear strength, the practical upper limit is 20.0 MPa. As the copper substrate, No. 32R (manufactured by Sunhayato Corporation) can be used, and as the glass chip, chip-shaped EAGLE XG (manufactured by Corning Corporation) can be used. The die shear test can be performed using a die shear tester (for example, Nordson's "DAGE 4000PLUS").

[0065] The peripheral encapsulant for display elements of the present invention is suitably used for encapsulating liquid crystal display elements and organic EL display elements.

[0066] According to the present invention, it is possible to provide a peripheral sealant for display elements that can obtain a display element with excellent curability to long-wavelength light, excellent adhesion to metals, and excellent impact resistance.

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0068] (Preparation of the compound represented by formula (1)) 105 parts by mass of 2-hydroxyethyl acrylate, 114 parts by mass of ε-caprolactone, and 0.2 parts by mass of hydroquinone as a polymerization inhibitor were added to a reaction flask, and the mixture was stirred at 90°C for 5 hours using a mantle heater. Then, 148 parts by mass of phthalic anhydride was added and the mixture was stirred for a further 5 hours. Next, 170 parts by mass of bisphenol A diglycidyl ether was added to the resulting reaction product and the mixture was stirred at 90°C for 5 hours to obtain the compound represented by formula (1). １ H-NMR and １３ The compound represented by formula (1) obtained by C-NMR is R １ is a hydrogen atom, R ２ We confirmed that is an ethylene group, Ar is a 1,2-phenylene group, X is the ring-opened structure of ε-caprolactone, n is 1.01 (average value), and Ep is a structure derived from bisphenol A diglycidyl ether.

[0069] (Preparation of the compound represented by formula (3)) 34 parts by mass of isoeicosanedioic acid (Okamura Oil Co., Ltd., "SB-20"), 72 parts by mass of bisphenol F diglycidyl ether (Tokyo Chemical Industries Co., Ltd.), 0.1 parts by mass of triphenylphosphine as a catalyst, and 0.1 parts by mass of hydroquinone as a polymerization inhibitor were added to a reaction flask and the mixture was stirred at 110°C for 5 hours. Then, 18 parts by mass of acrylic acid (Tokyo Chemical Industries Co., Ltd.) was added and the mixture was stirred at 100°C for 8 hours. After that, the obtained product was washed three times with 100 parts by mass of water to obtain the compound represented by formula (3). １ The compound represented by formula (3) obtained by H-NMR, GPC, and FT-IR is R ３ We confirmed that all of them are hydrogen atoms, Y has a structure represented by formula (9) below, and Z has a structure represented by formula (10) below.

[0070]

[0071] In equation (9), * indicates the bonding position.

[0072]

[0073] In equation (10), * indicates the bonding position.

[0074] (Preparation of the compound represented by formula (7)) 5 parts by mass of N-ethylcarbazole, 2.81 parts by mass of 2,5-thiophenedicarboxylic acid dichloride, and 3.76 parts by mass of aluminum chloride were added to 40 mL of dichloromethane and stirred overnight at room temperature. 2.21 parts by mass of acetyl chloride and 3.76 parts by mass of aluminum chloride were added to the resulting reaction solution and stirred for a further 4 hours at room temperature. The resulting reaction solution was poured into ice water and the organic layer was extracted with ethyl acetate. The extracted solution was washed with saturated sodium bicarbonate aqueous solution and saline solution, then dried over anhydrous magnesium sulfate and concentrated to obtain product (A1). 3 parts by mass of the obtained product (A1), 0.76 parts by mass of hydroxylammonium chloride, and 0.86 parts by mass of pyridine were added to 30 mL of ethanol and stirred under reflux for 10 hours. The resulting reaction solution was poured into ice water and filtered. The filtrate was washed with water, dissolved in ethyl acetate, dried over anhydrous magnesium sulfate and concentrated to obtain product (B1). 1.5 parts by mass of the obtained product (B1) was dissolved in 25 parts by mass of N,N-dimethylformamide, and then 0.59 parts by mass of acetyl chloride was added. While cooling the resulting solution to below 10°C, 0.78 parts by mass of triethylamine was added dropwise, and the mixture was stirred at room temperature for 4 hours. The resulting reaction mixture was poured into water and filtered. The filtrate was purified by silica gel column chromatography using a mixed solvent of dichloromethane and hexane (dichloromethane:hexane = 2:1) to obtain the compound represented by formula (7) above. The structure of the obtained compound represented by formula (7) above is as follows: １ H-NMR, １３ This was confirmed by C-NMR and FT-IR.

[0075] (Preparation of the compound represented by formula (8)) 5 parts by mass of ethyl 3-(9H-carbazole-9-yl)propionate, 2.64 parts by mass of hexanoyl chloride, and 2.62 parts by mass of aluminum chloride were added to 80 mL of dichloromethane and stirred overnight at room temperature. 1.84 parts by mass of 2,5-thiophenedicarboxylic acid dichloride and 5.24 parts by mass of aluminum chloride were added to the resulting reaction solution and stirred for a further 4 hours at room temperature. The resulting reaction solution was poured into ice water and the organic layer was extracted with ethyl acetate. The extracted solution was washed with saturated sodium bicarbonate aqueous solution and saline solution, then dried over anhydrous sodium sulfate and concentrated to obtain product (A2). 4.0 parts by mass of product (A2) in 20 mL of ethanol were added to 2.77 parts by mass of 20% by mass sodium hydroxide aqueous solution and refluxed for 3 hours. After the reaction was complete, 50 mL of water was added, the solution was acidified with concentrated hydrochloric acid, and then extracted with ethyl acetate. The ethyl acetate layer was washed with water and saline solution, then dried over anhydrous sodium sulfate and concentrated to obtain product (B2). Three parts by mass of product (B2), 0.58 parts by mass of hydroxylammonium chloride, and 0.65 parts by mass of pyridine were added to 30 mL of ethanol and stirred under reflux for 10 hours. The resulting reaction mixture was poured into ice water and filtered. The filtrate was washed with water, dissolved in ethyl acetate, dried over anhydrous sodium sulfate and concentrated to obtain product (C2). One and a half parts by mass of product (C2) were dissolved in 20 parts by mass of N,N-dimethylformamide, and then 0.45 parts by mass of acetyl chloride was added. While cooling the resulting solution to below 10°C, 0.59 parts by mass of triethylamine was added dropwise and stirred at room temperature for 4 hours. The resulting reaction mixture was poured into water and filtered. The compound represented by formula (8) above was obtained by isolating the compound by silica gel column chromatography. The structure of the compound represented by formula (8) above is as follows: １ H-NMR, １３ This was confirmed by C-NMR and FT-IR.

[0076] (Examples 1-24, Comparative Examples 1-6) Each material was mixed and stirred in a planetary stirring device (Thinky Co., Ltd., "Awatori Rentaro") according to the mixing ratios shown in Tables 1-4 to obtain peripheral encapsulants for display elements in Examples 1-24 and Comparative Examples 1-6. The photopolymerization initiators used in the examples and comparative examples were dissolved in acrylonitrile to a concentration of 0.1 mg / mL, and the extinction coefficient at a wavelength of 450 nm was measured using a spectrophotometer (Hitachi High-Tech Science Corporation, "U-3900"). The results are shown in Tables 1-4.

[0077] (Measurement of fracture elongation and fracture strength of the cured material) The obtained peripheral sealant for the display element was measured using an LED lamp at a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ By irradiating the material with light for 30 seconds, a cured material measuring 45 mm in length, 5 mm in width, and 0.5 mm in thickness was obtained. The obtained cured material was subjected to a tensile test using a tensile testing machine (Shimadzu Corporation, "Autograph AG-Xplus") under the conditions of 25°C, a tensile speed of 10 mm / min, and a grip distance of 25 mm, and the elongation at break and breaking strength were measured. The results are shown in Tables 1 to 4. Note that the peripheral encapsulants for display elements obtained in Comparative Examples 1 and 4 could not be sufficiently cured, and therefore the elongation at break and breaking strength could not be measured.

[0078] (Measurement of die shear strength) The obtained peripheral sealant for the display element was applied to a copper substrate (Sunhayato, "No. 32R"), and then a 0.6 mm thick glass chip (Corning, "Eagle XG") cut into a 5 mm long, 5 mm wide shape was placed on top. The measurement was then performed at a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ A laminate was obtained by curing the peripheral sealant for the display element by irradiating it with light for 30 seconds. The obtained laminate was subjected to a die shear test using a die shear tester (Nordson, "DAGE 4000PLUS") at 25°C and a speed of 30 mm / min, and the die shear strength was measured. The results are shown in Tables 1 to 4. Note that the laminates obtained using the peripheral sealant for the display element obtained in Comparative Example 1 and Comparative Example 4 could not have their die shear strength measured because the peripheral sealant for the display element could not be sufficiently cured.

[0079] <Evaluation> The following evaluation was performed on the obtained peripheral encapsulant for display elements. The results are shown in Tables 1 to 4.

[0080] (Curing properties to long-wavelength light) The obtained peripheral sealant for display elements was applied to a PET film (Lintec Corporation, "PET5011"), and the area around the applied peripheral sealant for display elements was surrounded by a 500 μm thick rubber sheet. Next, the peripheral sealant for display elements surrounded by the rubber sheet was exposed to UV light using a UV lamp at a wavelength of 450 nm and an illuminance of 100 mW / cm². ２ The material was irradiated with light for 30 seconds to obtain a cured product. The back surface (the side not irradiated with light) of the obtained cured product was examined, and its curability to long-wavelength light was evaluated according to the following criteria: A: The material was sufficiently cured with no tack on the back surface. B: The back surface was not cured, or the curing was insufficient and tack was observed.

[0081] (Impact Resistance) Based on the results of the above "(Measurement of Elongation and Strength of the Cured Material)", toughness (impact resistance) was evaluated according to the following criteria: AA: When the elongation of the cured material is 5.0% or more and the strength of the cured material is 5.0 MPa or more. A: When the elongation of the cured material is 5.0% or more and the strength of the cured material is 2.0 MPa or more and less than 5.0 MPa. B: When the elongation of the cured material is less than 5.0% and the strength of the cured material is less than 2.0 MPa, or when at least one of the elongation of the cured material and the strength of the cured material could not be measured.

[0082] (Adhesion to Metals) Based on the results of the "(Measurement of Die Shear Strength)" above, the adhesion to metals was evaluated according to the following criteria: AA: When the die shear strength was 8.0 MPa or higher A: When the die shear strength was 5.0 MPa or higher but less than 8.0 MPa B: When the die shear strength was less than 5.0 MPa, or when the die shear strength could not be measured

[0083] (Storage Stability under Yellow Lamp) 10 g of the obtained peripheral sealant for display elements was added to a colorless, transparent screw tube and left under a yellow lamp (manufactured by Brinis) for 8 hours. The peripheral sealant for display elements was visually inspected after the inspection and its storage stability under a yellow lamp was evaluated according to the following criteria: A: No gelation was observed in the peripheral sealant for display elements B: Gelation was observed in the peripheral sealant for display elements Note that even if the storage stability evaluation result under a yellow lamp is B, the peripheral sealant for display elements can be used without problems depending on the application and method of use.

[0084]

[0085]

[0086]

[0087]

[0088] According to the present invention, it is possible to provide a peripheral sealant for display elements that can obtain a display element with excellent curability to long-wavelength light, excellent adhesion to metals, and excellent impact resistance.

Claims

1. A peripheral encapsulant for a display element comprising a curable resin and a photopolymerization initiator, wherein the curable resin comprises a monofunctional polymerizable compound having one polymerizable functional group in one molecule and a polyfunctional polymerizable compound having two or more polymerizable functional groups in one molecule, the monofunctional polymerizable compound comprises monofunctional polymerizable compound A having no hydroxyl group, carboxyl group, or phosphate group, and having one polymerizable functional group in one molecule and at least one structure selected from the group consisting of a phenyl group, an imide bond, and an alicyclic hydrocarbon skeleton, and monofunctional polymerizable compound B having one polymerizable functional group in one molecule and at least one structure selected from the group consisting of a hydroxyl group, a carboxyl group, and a phosphate group, and the photopolymerization initiator comprises a photopolymerization initiator having an extinction coefficient of 75 mL / g·cm or more at a wavelength of 450 nm.

2. The peripheral sealing agent for a display element according to claim 1, wherein the monofunctional polymerizable compound B has at least one structure selected from the group consisting of a carboxyl group and a phosphate group.

3. The peripheral sealant for a display element according to claim 1 or 2, wherein the polyfunctional polymerizable compound comprises a compound having two or more polymerizable functional groups and a linear or branched chain hydrocarbon skeleton having 5 or more carbon atoms in one molecule.

4. The peripheral sealant for a display element according to claim 1, 2, or 3, wherein the polyfunctional polymerizable compound comprises a polyfunctional urethane (meth)acrylate having two or more (meth)acryloyl groups and a urethane bond in one molecule.

5. The peripheral sealing agent for the display element has a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ The peripheral sealant for a display element according to claim 1, 2, 3, or 4, wherein the cured product obtained by irradiating it with light for 30 seconds exhibits a breaking elongation of 5.0% or more when subjected to a tensile test under the conditions of 25°C, a tensile speed of 10 mm / min, and a gripping distance of 25 mm.

6. The peripheral sealing agent for the display element has a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ A peripheral sealant for a display element according to claim 1, 2, 3, 4, or 5, wherein the cured product obtained by irradiating it with light for 30 seconds has a breaking strength of 2.0 MPa or more when subjected to a tensile test under the conditions of 25°C, a tensile speed of 10 mm / min, and a gripping distance of 25 mm.

7. The peripheral sealant for the display element is applied to a copper substrate, and then a glass chip measuring 5 mm in length, 5 mm in width, and 0.6 mm in thickness is placed on top, with a wavelength of 450 nm and an illuminance of 100 mW / cm. ２ The peripheral sealant for a display element according to claim 1, 2, 3, 4, 5, or 6, wherein the die shear strength of the laminate obtained by curing the peripheral sealant for the display element by irradiating it with light for 30 seconds is 5.0 MPa or more when a die shear test is performed under the conditions of 25°C and a speed of 30 mm / min.

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