TW201538697A - Transparent sealing agent for display element - Google Patents

Abstract

The purpose of the present invention is to provide a transparent sealing agent for a display element, the transparent sealing agent exhibiting excellent photocurability, adhesive properties and cured product transparency and being able to inhibit adverse effects on display performance, such as generation of outgas. The present invention is a transparent sealing agent for a display element, the transparent sealing agent containing a polythiol compound having 2 or more thiol groups per molecule, a polyene compound having 2 or more carbon-carbon double bonds per molecule, and a photopolymerization initiator. The photopolymerization initiator contains a photopolymerization initiator A, which consists of a benzyldimethylketal compound and/or an [alpha]-aminoalkylphenone compound, and a photopolymerization initiator B having a functional group that exhibits hydrogen bonding properties.

Description

Transparent sealant for display components

The present invention relates to a transparent sealant for a display element which is excellent in transparency of photocurability, adhesion, and cured product, and which can suppress adverse effects on display performance due to generation of outgas.

In recent years, liquid crystal display elements, organic EL display elements, and the like have been widely used as display elements having characteristics such as thinness, light weight, and low power consumption. Among these display elements, a photocurable resin composition is usually used for sealing a liquid crystal or a light-emitting layer or the like.

The liquid crystal display element is usually manufactured by arranging two transparent substrates with electrodes at a predetermined interval, sealing the periphery thereof with a sealant to form a cell, and setting the liquid crystal to a part thereof. The liquid crystal injection port is injected into the cell, and the liquid crystal injection port is sealed with a sealing agent using a liquid crystal injection port. In the past, a one-component or two-liquid type curable epoxy resin composition, or a photocurable acrylic resin composition described in Patent Document 1 or the like is widely used as the sealing agent for a liquid crystal injection port. However, the one-component type hardenable epoxy resin composition is generally inferior in productivity due to heating at a high temperature for a long period of time, and the two-liquid type hardenable epoxy resin composition requires labor for mixing the main agent and the hardener. Moreover, it must be used within the service life (applicable period) after mixing, so workability is particularly poor. On the other hand, light hard The acrylic resin composition of the chemical composition is excellent in workability or productivity, but has problems in that it contaminates the liquid crystal due to strong interaction with the liquid crystal to cause color unevenness, or acrylic acid remaining in the manufacturing process of the display element. The resin causes a large amount of outgassing, or the transparency of the cured product is poor.

Further, in the organic EL display device, when the organic light-emitting material layer or the electrode is exposed to the outside air, the performance thereof is drastically deteriorated. Therefore, in order to improve the stability or durability of the organic EL display element, an inorganic material film is proposed. A method in which an organic light-emitting material layer is coated with an electrode and sealed by a resin film. For example, Patent Document 2 discloses a method of forming a resin film composed of an acrylic resin composition on an inorganic material film. However, in such a case, since ultraviolet curing hardening under oxygen occurs, there is a problem that outgas is generated by the unreacted acrylic resin.

Patent Document 3 discloses a photocurable resin composition containing a photocationic polymerizable compound and an onium borate complex as a curable resin composition having a small amount of outgassing. However, a sealant which improves the effects of hardenability, adhesion, transparency, and suppression of outgassing is sought.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. Hei 6-160972

Patent Document 2: Japanese Laid-Open Patent Publication No. 2001-307873

Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-336314

An object of the present invention is to provide a display element which is excellent in photocurability, adhesion, and transparency of a cured product, and which can suppress adverse effects on display performance due to generation of outgas.

The present invention relates to a transparent sealant for a display element comprising: a polythiol compound having two or more thiol groups in one molecule, and having two or more carbon-carbon double bonds in one molecule An ene compound, and a photopolymerization initiator; and the above photopolymerization initiator comprises: a benzil dimethylketal compound and/or an α-aminoalkyl phenone compound A photopolymerization initiator A and a photopolymerization initiator B having a hydrogen bonding functional group. Hereinafter, the present invention will be described in detail.

The inventors of the present invention have studied the use of a resin containing a polythiol compound having two or more thiol groups in one molecule and a polyene compound having two or more carbon-carbon double bonds in one molecule in place of the acrylic resin. The composition (hereinafter also referred to as "ene-thiol resin composition") is a transparent sealing agent for display elements which is excellent in transparency and transparency of a cured product. However, even in the case of using such an ene-thiol-based resin composition, the problem of generating outgassing cannot be completely solved. Further, there is a case where the obtained transparent sealing agent for a display element may contaminate the liquid crystal when it is in contact with the liquid crystal of the liquid crystal display element, or may be organically irradiated when it is in contact with the organic light-emitting material layer of the organic EL display element. The material layer causes damage.

Therefore, the present inventors have conducted an effort to find that photohardenability, adhesion, and the like can be obtained by combining a specific photopolymerization initiator in an ene-thiol resin composition. The transparent sealant for a display element which is excellent in transparency of a cured product and suppresses generation of outgassing or contamination of liquid crystal, and the like.

In the present specification, the above-mentioned "display element" means a liquid crystal display element and an organic EL display element, and the "transparent" means that the average transmittance of visible light in a visible light region having a wavelength of 380 to 780 nm is 80% or more.

The transparent sealant for display elements of the present invention contains a photopolymerization initiator.

The photopolymerization initiator contains a photopolymerization initiator A composed of a benzoin dimethyl ketal compound and/or an α-aminoalkyl phenone compound, and photopolymerization having a hydrogen bonding functional group. Starter B. By using the photopolymerization initiator A in combination with the photopolymerization initiator B, the transparent sealing agent for a display element of the present invention is excellent in photocurability and can suppress display due to generation of outgas. The adverse effects of performance.

In the following, the matters common to the photopolymerization initiator A and the photopolymerization initiator B are treated only by the "photopolymerization initiator".

The photopolymerization initiator A has an effect of suppressing the yellowing of the obtained cured product and improving the photocurability of the transparent sealing agent for a display element of the present invention.

The photopolymerization initiator A is composed of a benzoin dimethyl ketal compound and/or an α-aminoalkyl phenone compound.

Examples of the benzoin dimethyl ketal compound include 2,2-dimethoxy-1,2-diphenylethane-1-one.

The α-aminoalkylphenone compound may, for example, be 2-methyl-1-(4-methylthiophenyl)-2-morpholinylpropan-1-one or 2-benzyl-2-di Methylamino-1-(4-morpholinylphenyl)butanone-1, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4) -(4-morpholinyl)phenyl)-1-butanone and the like.

The commercially available one of the above-mentioned photopolymerization initiators A, for example, IRGACURE 651, IRGACURE 907, IRGACURE 369, IRGACURE 379 (above, manufactured by BASF Corporation), and the like.

The lower limit of the 365 nm absorption coefficient of the photopolymerization initiator A is preferably 400 mL/g ‧ cm. By using the photopolymerization initiator having an absorption coefficient of 400 mL/g‧cm or more as the photopolymerization initiator A, the photocurability of the obtained transparent sealing agent for a display element can be sufficiently improved. A lower limit of the light absorption coefficient of the photopolymerization initiator A is preferably 500 mL/g‧cm, and a lower limit is preferably 550 mL/g‧cm. The higher the light absorption coefficient of the photopolymerization initiator A, the higher the upper limit, and the upper limit is not particularly limited, and the substantial upper limit is 15000 mL/g‧ cm. In addition, the above-mentioned "absorption coefficient at 365 nm" can be dissolved in a solvent so that the concentration is 0.1 mg/mL, and the measurement can be carried out using a spectrophotometer.

The solvent is not particularly limited as long as it can dissolve the compound to be measured and does not have absorbance at the absorption wavelength measured, and examples thereof include acetonitrile and methanol.

In the case where the above-mentioned photopolymerization initiator A is used as the photopolymerization initiator in a large amount so that the obtained transparent sealing agent for a display element has sufficient photocurability, it is likely to cause outgassing, etc. problem.

In the transparent sealing agent for a display element of the present invention, the photopolymerization initiator B is used in addition to the photopolymerization initiator A, whereby generation of outgassing and the like can be suppressed, and adverse effects on display performance can be suppressed.

The photopolymerization initiator B is composed of a compound other than the photopolymerization initiator A and has a hydrogen bonding functional group.

Examples of the hydrogen-bondable functional group include an -OH group, a -NH ₂ group, a -NHR group (R represents an aromatic, an aliphatic hydrocarbon, or a derivative thereof), a -COOH group, and a -CONH ₂ group. a functional group such as a -NHOH group or a residue such as a -NHCO- bond, a -NH- bond, a -CONHCO- bond, or a -NH-NH- bond. Among them, a -OH group is preferred.

As the photopolymerization initiator B, an α-hydroxyalkylphenone compound is preferred.

The above α-hydroxyalkylphenone compound may, for example, be 2-hydroxy-1-(4-(4-(2-hydroxy-2-methyl-propenyl)-benzyl)phenyl)-2- Methyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyl) Ethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl) Phenyl)propane).

The commercially available ones of the photopolymerization initiators B include, for example, IRGACURE 127, IRGACURE 184, IRGACURE 1173, IRGACURE 2959 (above, manufactured by BASF Corporation), ESACURE KIP 150 (manufactured by Lamberti Co., Ltd.), and the like.

The content ratio of the photopolymerization initiator A to the photopolymerization initiator B is preferably in terms of weight ratio from the viewpoint of the effect on the display performance or the photocurability due to the generation of gas, or the like. Photopolymerization initiator A: photopolymerization initiator B = 1:1 to 1:5. The content ratio of the photopolymerization initiator A to the photopolymerization initiator B is preferably a photopolymerization initiator A: photopolymerization initiator B = 1:2 to 1:3 by weight.

The content of the photopolymerization initiator as a whole is 100 parts by weight based on the total of the polythiol compound and the polyene compound, and the lower limit is 2 weights, in terms of hardening reactivity, workability, or uniformity of the cured product. Preferably, the upper limit is 5 parts by weight. A more preferred lower limit of the content of the photopolymerization initiator as a whole is 3 parts by weight, and a more preferred upper limit is 4 parts by weight.

The lower limit of the molecular weight of the above photopolymerization initiator is preferably 250, and preferably the upper limit is 1,500, from the viewpoint of gas generation or hardenability. By using a molecular weight of 250~ The photopolymerization initiator of 1500 is excellent in the hardenability of the transparent sealing agent for a display element of the present invention, and the generation of outgas can be suppressed. Among them, the lower limit of the molecular weight of the photopolymerization initiator is preferably 300, more preferably 1000, and further preferably 350, and further preferably 700.

The transparent sealing agent for a display element of the present invention contains a polythiol compound having two or more thiol groups in one molecule (hereinafter also referred to simply as "polythiol compound"), and has two or more in one molecule. A polyene compound of carbon-carbon double bond (hereinafter also referred to simply as "polyene compound") is used as a photopolymerizable compound. The transparent sealant for a display element of the present invention containing these components is excellent in adhesion and transparency of a cured product.

The polythiol compound may, for example, be an aliphatic polythiol such as ethanedithiol, propylenedithiol, hexanedithiol or decanedithiol, or methylphenyl-2,4-dithiol or the like. An aromatic polythiol such as xylene dithiol or a cyclic sulfur such as a polythiol compound containing a 1,4-dithiane ring represented by the following formula (1) Ether compound, ester-containing polythiol compound, diethylenedithiol, triethylenedithiol, tetraethylenedithiol, thiobisethanedithiol, thiotriethyldithiol, thiotetraethyl Dithiol, tris-(3-mercaptopropoxy)-ethyl isocyanurate, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate ), pentaerythritol-tetrakis(3-mercaptopropionate), dipentaerythritol-hexa(3-mercaptopropionate), 4-(mercaptomethyl)-3,6-dithiaoctane -1,8-dithiol, 4,8-bis(decylmethyl)-3,6,9-trithiaundecane-1,11-dithiol, or 1,3,4,6- Other polythiol compounds such as tetradecyl propyl guanyl glycoluril. These polythiol compounds may be used singly or in combination of two or more.

In the formula (1), I represents an integer of 1 to 5.

Specific examples of the polythiol compound containing a 1,4-dithiane ring represented by the above formula (1) include, for example, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-di. Mercaptoethyl-1,4-dithiane, 2,5-dimercaptopropyl-1,4-dithiane, 2,5-dimercaptobutyl-1,4-dithiane, and the like.

In the above polythiol compound, in order to obtain a transparent sealant for a display element obtained, the polythiol compound having an ester bond is preferred.

Specific examples of the above-mentioned ester-containing polythiol compound include trimethylolpropane tris(3-mercaptopropionate) and tris-((3-mercaptopropoxy)-ethyl isocyanurate. , pentaerythritol tetradecyl acetate, pentaerythritol tetrakis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), and the like.

Further, the polythiol compound preferably has 3 to 6 thiol groups in one molecule, and more preferably 4 to 6 thiol groups in one molecule, from the viewpoint of hardenability or reliability.

Examples of the polyene compound include a (meth)allyl compound, a (meth)acrylic compound, and divinylbenzene. These polyene compounds may be used singly or in combination of two or more.

In the present specification, the above "(meth)allyl" means allyl or methallyl, and the above "(meth)acrylic" means acrylic acid or methacrylic acid.

Examples of the (meth)allyl compound include, for example, triallyl cyanurate, triallyl isocyanurate, trimethallyl isocyanurate, and maleic acid. Diallyl ester, diallyl adipate, diallyl phthalate, triallyl trimellitate, tetraallyl pyromellitate, glycerol diallyl ether, Trimethylolpropane diallyl ether, neopentyl alcohol diallyl ether, 1,3-diallyl-5-glycidyl isocyanurate, 1,3,4,6-tetraene Propyl glycoluril, 1,3,4,6-tetraallyl-3a-methyl glycoluril, 1,3,4,6-tetraallyl-3a, 6a-dimethylglycolil, and the like. Among them, from the viewpoint of hardenability or reliability, it is preferred to have an iso-cyanuric acid ring skeleton or a glycoluril ring skeleton, more preferably a glycoluril ring skeleton, and further preferably 1, 3, 4, 6-tetraallyl glycoluril, 1,3,4,6-tetraallyl-3a-methyl glycoluril, 1,3,4,6-tetraallyl-3a, 6a-dimethylglycine Urea.

The (meth)acrylic compound is not particularly limited as long as it has two or more methacryl groups or acryl groups in one molecule, and examples thereof include (meth)acrylic acid and epoxy compounds. An epoxy (meth) acrylate obtained by the reaction, an ester compound obtained by reacting (meth)acrylic acid with a compound having a hydroxyl group, by reacting an isocyanate with a (meth)acrylic acid derivative having a hydroxyl group The obtained (meth)acrylic acid amine ester and the like.

In the present specification, the above "(meth) acrylate" means acrylate or methacrylate, and the above "epoxy (meth) acrylate" means all epoxy groups in the epoxy compound. A compound formed by reacting with (meth)acrylic acid.

The epoxy (meth) acrylate is obtained by, for example, reacting (meth)acrylic acid and an epoxy compound in the presence of a basic catalyst by a conventional method.

Examples of the epoxy compound which is a raw material of the epoxy (meth) acrylate include a bisphenol A epoxy compound, a bisphenol F epoxy compound, a bisphenol S epoxy compound, and 2, 2'-. Diallyl bisphenol A type epoxy compound, hydrogenated bisphenol type epoxy compound, propylene oxide addition bisphenol A type epoxy compound, resorcinol type epoxy compound, biphenyl type epoxy compound, sulfur Ether type epoxy compound, diphenyl ether type epoxy compound, dicyclopentadiene type epoxy compound, naphthalene type epoxy compound, phenol novolac type epoxy compound, o-cresol novolak type epoxy compound, bicyclo ring E Diene novolak type epoxy compound, biphenyl novolac type epoxy compound, naphthol novolac type epoxy compound, epoxy propylamine type epoxy compound, alkyl polyol type epoxy compound, rubber modified epoxy A compound, a glycidyl ester compound, a bisphenol A type episulfide compound, or the like.

As the bifunctional one of the ester compounds obtained by reacting (meth)acrylic acid with a compound having a hydroxyl group, for example, 1,3-butanediol di(meth)acrylate, 1,4-butyl Diol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(a) Acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, poly Propylene glycol (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (a) Acrylate, ethylene oxide addition bisphenol A di(meth) acrylate, propylene oxide addition bisphenol A di(meth) acrylate, ethylene oxide addition bisphenol F bis (A) Acrylate, dimethylol dicyclopentadienyl di(meth) acrylate, neopentyl glycol di(meth) acrylate, ethylene oxide modified iso-cyanuric acid di(methyl) Acrylate, 2-hydroxy-3-(methyl) propylene oxide (meth) acrylate Propyl ester, carbonate diol di(meth) acrylate, polyether diol di(meth) acrylate, polyester diol di(meth) acrylate, polycaprolactone diol di(methyl) Acrylate, polybutadiene diol di(meth) acrylate, and the like.

Further, examples of the trifunctional or higher functional group in the ester compound include trimethylolpropane tri(meth)acrylate, propylene oxide addition trimethylolpropane tri(meth)acrylate, and epoxy B. Alkane addition to trimethylolpropane tri(meth)acrylate, caprolactone modified trimethylolpropane tri(meth)acrylate, ethylene oxide addition to isocyanuric acid tris(methyl) Acrylate, neopentyl alcohol tri(meth) acrylate, glycerol tri(meth) acrylate, propylene oxide addition glycerol tri(meth) acrylate, tris(methyl) propylene methoxyethyl phosphate Di-trimethylolpropane tetra(meth)acrylic acid Ester, neopentyltetrakis(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like.

Further, in view of hardenability or reliability, the polyene compound preferably has 3 to 6 carbon-carbon double bonds in one molecule, more preferably 4 to 6 carbon-carbons in one molecule. Double key.

The content of the polyene compound is preferably 20 parts by weight, based on 100 parts by weight of the total of the polythiol compound and the polyene compound, from the viewpoint of suppressing the generation of outgas by the unreacted material. The upper limit is preferably 80 parts by weight. A more preferred lower limit of the content of the above polyene compound is 30 parts by weight, and a more preferred upper limit is 70 parts by weight.

The transparent sealant for a display element of the present invention preferably contains a thioether oligomer formed by reacting the above polythiol compound with the above polyene compound. By containing the above thioether oligomer, the viscosity of the transparent sealant for a display element is appropriately increased, and unevenness is less likely to occur during coating.

Further, when the thioether oligomer is contained, the content of the polyene compound, the total of the polythiol compound and the polyene compound, and the blend ratio of the polythiol compound and the polyene compound Refers to the raw materials containing the above thioether oligomers.

The thioether oligomer is obtained by light or heat the above polythiol compound and the above polyene compound in an amount ranging from 3:1 to 1:3 (mole ratio) with respect to the above polythiol compound. The addition polymerization is carried out by light irradiation or heating in the presence of a polymerization initiator, and is obtained as a polymer in the reaction mixture. From the viewpoint of controlling the reactivity, the above-mentioned addition polymerization reaction is preferably carried out in the presence of a thermal polymerization initiator.

Furthermore, the above thioether oligomer may contain unreacted thiol groups or unreacted carbon-carbon double bonds, or Does not contain unreacted thiol groups or unreacted carbon-carbon double bonds. That is, it may be a thioether oligomer which does not contain a thiol group or an unreacted carbon-carbon double bond which is sufficiently obtained by addition polymerization of the above polythiol compound and the above polyene compound, and may be contained by A thioether oligomer obtained by stopping the reaction in the course of the addition polymerization reaction to obtain an unreacted thiol group or an unreacted carbon-carbon double bond.

The thermal polymerization initiator is not particularly limited, but a thermal radical polymerization initiator is preferably used.

The thermal radical polymerization initiator may be, for example, an azo compound or an organic peroxide.

Examples of the azo compound include 2,2'-azobis(2,4-dimethylvaleronitrile), azobisisobutyronitrile, and the like.

Examples of the organic peroxide include benzammonium peroxide, ketone peroxide, peroxyketal, hydrogen peroxide, dialkyl peroxide, peroxyester, dimercapto peroxide, and peroxide. Carbonate and the like.

In the addition polymerization reaction of the above polythiol compound and the polyene compound, the molar number of the thiol group of the polythiol compound relative to the molar number of the carbon-carbon double bond of the polyene compound (the thiol group) When the number of ears/molar number of the carbon-carbon double bond is 0.15 or less, the polyene compound is usually left as an unreacted component in the obtained reaction mixture.

The lower limit of the weight average molecular weight of the above thioether oligomer is preferably 1,000, and preferably the upper limit is 8,000, from the viewpoint of preventing unevenness in coating or coating properties. A more preferred lower limit of the weight average molecular weight of the above thioether oligomer is 2,000, and a more preferred upper limit is 6000.

In the present specification, the "weight average molecular weight" is a value obtained by gel permeation chromatography (GPC) and obtained by polystyrene conversion. As measured by GPC For the column to be used for the weight average molecular weight in terms of polystyrene, for example, Shodex LF-804 (manufactured by Showa Denko Co., Ltd.) or the like can be mentioned.

The transparent sealant for a display element of the present invention may contain a curable resin other than the above polythiol compound and the above polyene compound.

The curable resin is not particularly limited as long as it is a curing reaction by light or heat, and examples thereof include an epoxy resin or a part (meth) which is a raw material of the epoxy (meth) acrylate. Acrylic modified epoxy resin and the like.

In the present specification, the "partial (meth)acrylic modified epoxy resin" refers to a resin having one or more epoxy groups and one (meth)acrylonitrile group in one molecule. In the present specification, the above "(meth)acryl fluorenyl group" means an acryl fluorenyl group or a methacryl fluorenyl group.

The above-mentioned partial (meth)acrylic acid-modified epoxy resin can be obtained, for example, by reacting one epoxy group of an epoxy resin having two or more epoxy groups in one molecule with (meth)acrylic acid.

The transparent sealant for display elements of the present invention may also contain a heat hardener.

The above-mentioned thermosetting agent is preferably one in which the cured product after curing is transparent, and examples thereof include a thiol compound, an imidazole derivative, an amine compound, a polyphenol compound, and an acid anhydride. The commercially available ones of the above-mentioned heat curing agents include, for example, HN-2200, HN-2000, HN-5500, MHAC-P (above, manufactured by Hitachi Chemical Co., Ltd.), Fujicure 7000, Fujicure 7001, Fujicure 7002, and Tohide 410- N, Tohmide 215-70X, Tohmide 423, Tohmide 437, Tohmide TXC-636-A (above, manufactured by T&K TOKA Co., Ltd.), MEH-8000H, MEH-8005 (manufactured by Mingwa Kasei Co., Ltd.), and the like.

The transparent sealant for a display element of the present invention may further contain an adhesion imparting agent.

The above-mentioned adhesion imparting agent may, for example, be 3-methylpropenyloxypropyltrimethoxy. Decane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, N-(aminoethyl)aminopropyltrimethoxydecane, A decane coupling agent such as mercaptopropyltrimethoxydecane, a titanium coupling agent, or an aluminum coupling agent. These adhesion imparting agents may be used singly or in combination of two or more.

The transparent sealant for a display element of the present invention may contain a stabilizer for oxidation resistance or the like.

Examples of the stabilizer include 2,2'-methylenebis-(4-methyl-6-tert-butylphenol) and 4,4'-butylenebis-(6-t-butyl- 3-methylphenol), 2,2'-methylenebis-(4-ethyl-6-tert-butylphenol), and the like. These stabilizers may be used singly or in combination of two or more.

The transparent sealant for a display element of the present invention may further contain the above-mentioned thermal polymerization initiator, filler, hardening accelerator, plasticizer, surfactant, flame retardant, and the like without departing from the object of the present invention. Additives such as antistatic agents, defoamers, leveling agents, UV absorbers, and organic solvents.

The method for producing the transparent sealant for a display element of the present invention includes, for example, a polythiol compound, a polyene compound, a photopolymerization initiator, a thermal polymerization initiator, or an adhesion-imparting agent added as needed, using a stirrer. The method of uniform mixing, and the like.

The viscosity of the transparent sealant for a display element of the present invention measured at 20 ° C and 20 rpm using a conical rotor type viscometer from the viewpoint of composition unevenness, coating properties, and display characteristics of display elements The preferred lower limit is 0.4 Pa ‧ and the preferred upper limit is 40 Pa ‧ s. A lower limit of the above viscosity is 0.5 Pa s, a more preferred upper limit is 35 Pa s, and a preferred lower limit is 1 Pa ‧ s, and a preferred upper limit is 25 Pa ‧ s.

The transparent sealant for a display element of the present invention can be cured by light irradiation. The method of photocuring the display element of the present invention by a transparent sealing agent may, for example, be a method of irradiating light having a wavelength of 300 to 400 nm and an integrated light amount of 300 to 3000 mJ/cm ² .

Examples of the light source for irradiating light to the transparent sealant for a display element of the present invention include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an excimer laser, a chemical lamp, a black light, a microwave excited mercury lamp, and a metal. Halide lamps, sodium lamps, halogen lamps, xenon lamps, LED lamps, fluorescent lamps, sunlight, electron beam irradiation devices, and the like. These light sources may be used singly or in combination of two or more.

Examples of the means for irradiating light to the transparent sealing agent for a display element of the present invention include simultaneous irradiation of various light sources, sequential irradiation with a time difference, combined irradiation of simultaneous irradiation and sequential irradiation, and any irradiation means.

According to the present invention, it is possible to provide a display element which is excellent in light curability, adhesion, and transparency of a cured product, and which can suppress adverse effects on display performance due to generation of outgas.

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited to the examples.

(Examples 1 to 23, Comparative Examples 1 to 11)

According to the blending ratios shown in Tables 1 to 4, each of the materials was heated and mixed at 70 ° C for 3 hours using a stirrer ("Sany Electric HEIDON BLH300" manufactured by Shinto Scientific Co., Ltd.), thereby preparing Example 1 ~22 and Comparative Examples 1 to 11 are transparent sealants for display elements.

Further, according to the blending ratios shown in Table 3, each of the materials was mixed at room temperature for 1 hour using a stirrer ("Sany Electric HEIDON BLH300" manufactured by Shinto Scientific Co., Ltd.), thereby preparing Example 23 The display element is made of a transparent sealant.

<evaluation>

The transparent sealant for each display element obtained in the examples and the comparative examples was evaluated by the following method. The results are shown in Tables 1 to 4.

(1) Weight average molecular weight of thioether oligomer

The sealant for each display element obtained in the examples and the comparative examples was determined by gel permeation chromatography (GPC) using Shodex LF-804 (manufactured by Showa Denko Co., Ltd.) as a column to determine the thioether in the sealant. The weight average molecular weight of the oligomer based on polystyrene.

(2) Viscosity

The viscosity of each of the sealing members for display elements obtained in the examples and the comparative examples was measured at 20 ° C and 20 rpm using a conical rotor type viscometer ("TV-22 type" manufactured by Toki Sangyo Co., Ltd.).

(3) Coating properties

The applicability in the case where each of the sealing members for display elements obtained in the examples and the comparative examples was applied to a glass substrate by a slit coater was evaluated. The coating by a slit coater was carried out under the conditions of a speed of 50 mm/sec and a thickness after coating of 50 μm . The case where the coating can be applied without abrasion or sag is evaluated as "○", and the case where abrasion or sag occurs is evaluated as "△", which causes a large coating omission or uneven coating, or is completely uncoated. The situation of cloth is evaluated as "X".

(4) Sturability

Each of the display elements obtained in the examples and the comparative examples was applied onto a glass substrate with a transparent sealing agent, and light was irradiated so that the integrated light amount became 1000 mJ/cm ² using an LED lamp having a wavelength of 365 nm. Thereafter, the reaction rate was measured by the amount of reduction of the carbon-carbon double bond group (acrylic group or allyl group) by an analytical method using FT-IR. When the reaction rate of the carbon-carbon double bond group is more than 80%, it is set to "◎", and when it is more than 70% and 80% or less, it is set to "○", and when it is more than 50% and 70% or less, it is set. In the case of "△", the case of 50% or less was set to "X", and the hardenability was evaluated.

(5) Adhesiveness

0.05 g of each of the transparent sealants for display elements obtained in the examples and the comparative examples was applied onto a glass substrate using a micropipette. The substrate was bonded to another glass substrate on which the separator was placed at a pitch of 50 μm, and an LED lamp having a wavelength of 365 nm was used to irradiate light so that the integrated light amount was 1000 mJ/cm ² to prepare a laminate for evaluation. Sample. The obtained adhesion evaluation sample was subjected to a peeling test under the conditions of a peeling speed of 5 mm/min using EZ GRAPH (manufactured by Shimadzu Corporation), and the adhesion was measured. The case where the adhesion force is 1.5 N/cm or more is set to "○", the case where 1.0 N/cm or more and less than 1.5 N/cm is set to "△", and the case where the force is less than 1.0 N/cm is set to "". ×", and the adhesion is evaluated.

(6) Transparency of hardened materials

Each of the display elements obtained in the examples and the comparative examples was sandwiched between the PET resin film by a transparent sealing agent, and an LED lamp having a wavelength of 365 nm was used to irradiate light so that the integrated light amount was 1000 mJ/cm ² to prepare a thickness of 100 μm . A sample for the measurement of the penetration rate. The obtained transmittance measurement sample was measured for the light transmittance at a wavelength of 380 to 780 nm using a spectrophotometer ("U-2900" manufactured by Hitachi High-Technologies Corporation). The case where the average transmittance of the wavelength 380 to 780 nm is 90% or more is set to "○", the case where 80% or more and less than 90% is set to "△", and the case where less than 80% is set to "×", and the transparency was evaluated.

(7) yellow degeneration

In the above "(6) Transparency of cured product", color analysis was performed when the light transmittance was measured, and a yellow index (YI) defined by JIS K 7373 was obtained. The case where YI was less than 1.2 was set to "○", and the case where YI was 1.2 or more was set to "x", and yellowing was evaluated.

(8) Outgas production

Each of the sealing members for display elements obtained in the examples and the comparative examples was applied by a slit coater so as to have a thickness of 50 μm after application, and an ultraviolet ray of 2000 mJ/cm ^{2 was} irradiated with an LED lamp having a wavelength of 365 nm. And form a film.

The obtained film was measured for a weight loss rate when heated to a temperature of 130 ° C at a temperature increase rate of 10 ° C/min using a thermal analyzer ("TG/DTA6200" manufactured by Seiko Instruments Co., Ltd.), and this was used as the amount of outgassing. When the amount of outgas production is less than 0.1%, it is set to "○", and when the amount of outgas is 0.1% or more and less than 0.3%, it is "△", and the amount of outgas is 0.3% or more. Set to "X" and evaluate the amount of outgassing.

(9) Display performance of display components

(9-1) Display performance of liquid crystal display elements

(Production of liquid crystal display element)

After forming an ITO electrode having a surface thickness of 1000 Å, two glass substrates (length 25 mm, width 25 mm, thickness 0.7 mm) having an alignment film having a thickness of 800 Å coated on the surface by spin coating were prepared, and used for one substrate. A thermosetting epoxy resin (peripheral sealant) is printed by pattern printing to set a liquid crystal injection port. Then, the substrate after the pattern printing was held at 80 ° C for 3 minutes to perform pre-drying and welding of the peripheral sealant to the substrate, and then returned to room temperature. Then, after the spacer of 5 μm was spread on the other substrate, the substrates were bonded together, and the peripheral sealant was hardened by a hot press heated to 130 ° C for 2 hours to obtain an empty liquid crystal display. element. After vacuuming the obtained liquid crystal display element, liquid crystal (manufactured by Merck Co., Ltd., "ZLI-4792") was injected from the injection port, and each of the display elements obtained by the examples and the comparative examples was injected with a transparent sealant. The inlet was sealed, and an LED lamp having a wavelength of 365 nm was used to irradiate ultraviolet rays of 2000 mJ/cm ^{2 to} harden the sealant. Thereafter, the liquid crystal was annealed at 120 ° C for 1 hour to prepare a liquid crystal display element.

(The alignment of the liquid crystal display elements is disordered)

The obtained liquid crystal display element was driven in a halftone display state by a voltage of 3.5 V, and the alignment disorder of the liquid crystal in the vicinity of the injection port was observed by a polarizing microscope. In the case where the alignment disorder is not confirmed, it is set to "◎", and it is confirmed that the situation of a slight misalignment of less than 0.5 mm is "○", and the case where the alignment disorder of 0.5 mm or more and less than 1 mm is confirmed is set to " △", the display performance of the liquid crystal display element was evaluated by setting a clear alignment disorder of 1 mm or more (dense color unevenness) to "x".

(9-2) Display performance of organic EL display elements

(Production of a substrate on which a laminate including an organic light-emitting material layer is disposed)

A substrate having an ITO electrode formed by a thickness of 1000 Å on a glass substrate (length 25 mm, width 25 mm, thickness 0.7 mm) was used as a substrate. The substrate was subjected to ultrasonic cleaning for 15 minutes by acetone, alkaline aqueous solution, ion-exchanged water, and isopropyl alcohol, respectively, and the isopropylidene was boiled. The alcohol was washed for 10 minutes, and further pretreated by a UV-ozone cleaner ("NL-UV253" manufactured by Laser Electronics Co., Ltd., Japan).

Then, the substrate was fixed to a substrate holder of a vacuum evaporation apparatus, and 200 mg of N,N'-bis(1-naphthyl)-N,N'-diphenylbenzidine (α- was introduced into the simmering crucible. NPD), 200 mg of tris(8-hydroxyquinolinyl)aluminum (Alq ₃ ) was placed in other different calcined sputum, and the vacuum chamber was depressurized to 1 × 10 ^-4 Pa. Thereafter, the crucible to which α-NPD was charged was heated, and α-NPD was deposited on the substrate at a deposition rate of 15 Å/s to form a hole transport layer having a film thickness of 600 Å. Then, the crucible to which Alq ₃ was charged was heated, and an organic light-emitting material layer having a film thickness of 600 Å was formed at a deposition rate of 15 Å/s. Thereafter, the substrate on which the hole transport layer and the organic light-emitting material layer are formed is transferred to another vacuum evaporation device, and 200 mg of lithium fluoride is introduced into the tungsten resistance heating boat in the vacuum evaporation device, and the other 1.0 g of aluminum wire was put into the tungsten boat. Thereafter, the pressure in the vapor deposition apparatus of the vacuum vapor deposition apparatus was reduced to 2 × 10 ^-4 Pa, and 5 Å of lithium fluoride was formed at a vapor deposition rate of 0.2 Å / s, and then a film was formed at a rate of 20 Å / s. 1000 Å aluminum. The inside of the vapor deposition device was returned to normal pressure by nitrogen gas, and the substrate on which the laminate of the organic light-emitting material layer of 10 mm × 10 mm was placed was taken out.

(covered by the inorganic material film A)

A mask having an opening of 13 mm × 13 mm is provided in a manner of coating the entire laminate of the substrate including the laminate of the organic light-emitting material layer, and the inorganic layer is formed by plasma CVD. Material film A.

The plasma CVD method is carried out under the following conditions, that is, using SiH ₄ gas and nitrogen as a material gas, the flow rate of each is set to 10 sccm and 200 sccm, and the RF power is set to 10 W (frequency 2.45 GHz), and the room temperature is set. The pressure in the chamber was set to 0.9 Torr at 100 °C.

The thickness of the inorganic material film A of the formed tantalum nitride was about 0.2 μm .

(Formation of resin protective film)

The substrate in which the laminate of the inorganic material film A was placed was placed in a vacuum apparatus, and 0.5 g of the transparent sealant for a display element obtained in each of the examples and the comparative examples was placed in a heating boat provided in a vacuum apparatus. The pressure was reduced to 10 Pa, and the transparent sealing agent for a display element was heated at 200 ° C in a portion including a square of 11 mm × 11 mm of the laminate, and vacuum vapor deposition was performed so as to have a thickness of 0.5 μm . Thereafter, a high-pressure mercury lamp was used in a vacuum atmosphere, and an LED lamp having a wavelength of 365 nm was used to irradiate light so that the integrated light amount was 2000 mJ/cm ² , and the display element was cured with a transparent sealant to form a resin protective film.

(covered by the inorganic material film B)

A mask having an opening of 12 mm × 12 mm was provided so as to cover the entirety of the 11 mm × 11 mm resin protective film of the substrate on which the resin protective film was formed, and the inorganic material film B was formed by a plasma CVD method to obtain a display element. (Organic EL display element).

The plasma CVD method was carried out under the following conditions, that is, SiH ₄ gas and nitrogen gas were used as raw material gases, and the flow rate of each was set to 10 sccm for SiH ₄ gas, 200 sccm for nitrogen gas, and 10 W for RF power (frequency 2.45 GHZ). The indoor temperature was set to 100 ° C, and the indoor pressure was set to 0.9 Torr.

The thickness of the inorganic material film B of tantalum nitride formed was about 1 μm.

(Display performance of organic EL display elements)

After exposing the produced organic EL display elements to conditions of 60 ° C and 90% RH for 100 hours and 500 hours, respectively, a voltage of 3 V was applied, and the light-emitting state (dark spots, presence or absence of extinction of the pixels) was visually observed. It is set to "◎" when there is no dark spot or the surrounding extinction, and the case where there is no dark spot or the surrounding extinction, but the light emission is slightly uneven is set to "○", and a dark spot or In the case of the peripheral extinction, "△" was set, and the case where the non-light-emitting portion was significantly enlarged was set to "x", and the display performance of the organic EL display element was evaluated.

[Industrial availability]

According to the present invention, it is possible to provide a transparent sealant for a display element which is excellent in photocurability, adhesion, and transparency of a cured product, and which can suppress adverse effects on display performance due to generation of outgas.

Claims (8)

A transparent sealant for a display element, comprising: a polythiol compound having two or more thiol groups in one molecule; a polyene compound having two or more carbon-carbon double bonds in one molecule; And a photopolymerization initiator; and the photopolymerization initiator contains: light composed of a benzil dimethylketal compound and/or an α-aminoalkyl phenone compound Polymerization initiator A, and photopolymerization initiator B having a hydrogen bonding functional group. A transparent sealant for a display element according to the first aspect of the invention, wherein the photopolymerization initiator B is an α-hydroxyalkylphenone compound. The transparent sealant for a display element according to the first or second aspect of the invention, wherein the ratio of the photopolymerization initiator A to the photopolymerization initiator B is photopolymerization initiator A by weight: photopolymerization Starting agent B = 1:1 ~ 1:5. A transparent sealant for a display element according to the first, second or third aspect of the invention, wherein the polythiol compound has 3 to 6 thiol groups in one molecule. A transparent sealant for a display element according to claim 1, 2, 3 or 4, wherein the polyene compound has 3 to 6 carbon-carbon double bonds in one molecule. A transparent sealant for a display element according to claim 1, 2, 3, 4 or 5, wherein the polyene compound has an iso-cyanuric ring skeleton or a glycoluril ring skeleton. A transparent sealant for a display element according to the sixth aspect of the invention, wherein the polyene compound has a glycoluril ring skeleton. A transparent sealant for a display element as claimed in claim 1, 2, 3, 4, 5, 6 or 7 It contains a thioether oligomer.