WO2015087714A1

WO2015087714A1 - Sealant for display element

Info

Publication number: WO2015087714A1
Application number: PCT/JP2014/081507
Authority: WO
Inventors: 卓夫鈴木; 和志伊藤; 山本　拓也; 由季小林
Original assignee: 積水化学工業株式会社
Priority date: 2013-12-09
Filing date: 2014-11-28
Publication date: 2015-06-18
Also published as: JP5798259B1; CN105706264B; TW201527502A; KR20160096538A; CN105706264A; JP2016015324A; JPWO2015087714A1

Abstract

The purpose of the present invention is to provide a sealant for a display element, having high shear bond strength with respect to adherends, allowing outgas production to be minimized, and affording excellent transparency to cured articles. The present invention is a sealant for a display element, containing a polythiol compound having two or more thiol groups per one molecule, a polyene compound having two or more carbon-carbon double bonds per one molecule, and a photopolymerization initiator, the storage elastic modulus of cured articles thereof at 80°C being 70-1,000 MPa.

Description

Sealant for display element

The present invention relates to a sealant for a display element that has high shear adhesive strength to an adherend, can suppress generation of outgas, and is excellent in transparency of a cured product.

In recent years, liquid crystal display elements, organic EL display elements, and the like are widely used as display elements having features such as thinness, light weight, and low power consumption. In these display elements, a photocurable resin composition is usually used for sealing a liquid crystal or a light emitting layer, bonding a substrate, an optical film, or a protective film.

In a liquid crystal display element, an optical film such as a polarizing film or a protective film is attached to the surface of a substrate via an adhesive. For example, Patent Document 1 discloses a pressure-sensitive adhesive for a polarizing film made of an acrylic resin composition.
A liquid crystal display element usually has two transparent substrates with electrodes facing each other at a predetermined interval, and the periphery thereof is sealed with a sealant to form a cell, and a liquid crystal injection port provided in a part thereof Then, the liquid crystal is injected into the cell, and the liquid crystal inlet is sealed by using a liquid crystal inlet sealing agent. Conventionally, as a sealing agent for liquid crystal inlets, a one-component or two-component curable epoxy resin composition, a photocurable acrylic resin composition as described in Patent Document 1, and the like have been widely used. Has been used. However, the one-pack type curable epoxy resin composition generally requires a long period of heating at a high temperature, so the productivity is inferior. The two-pack type curable epoxy resin composition is a mixture of a main agent and a curing agent. It takes time and effort to do this, and after mixing, it must be used within the pot life (pot life). On the other hand, the photo-curable acrylic resin composition is excellent in workability and productivity, but because of its strong interaction with the liquid crystal, it contaminates the liquid crystal and causes color unevenness. There existed a problem that a large amount of outgas was generated by the remaining acrylic resin, or the adhesiveness and transparency of the cured product were inferior.
In addition, in the organic EL display element, when the organic light emitting material layer and the electrode are exposed to the outside air, the performance of the organic EL display element deteriorates rapidly. Therefore, in order to increase the stability and durability of the organic EL display element, There has been proposed a method in which a material layer and an electrode are covered with a resin film via an inorganic material film and sealed. For example, Patent Document 2 discloses a method of forming a resin film made of an acrylic resin composition on an inorganic material film.

However, the acrylic photocurable resin composition disclosed in Patent Document 1 and Patent Document 2 generates a large amount of outgas due to the acrylic resin remaining in the manufacturing process of the display element, and the adhesion and curing. There was a problem that the transparency of things was inferior.

JP 2010-196001 A JP 2001-307873 A

An object of the present invention is to provide a sealant for a display element that has a high shear adhesive strength to an adherend, can suppress generation of outgas, and is excellent in transparency of a cured product. To do.

The present invention contains 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. It is a sealant for display elements having a storage elastic modulus at 80 ° C. of 70 to 1000 MPa.
The present invention is described in detail below.

The present inventor has developed 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 for the purpose of suppressing generation of outgas. And the like (hereinafter also referred to as “ene-thiol resin composition”) were studied. However, when such an ene-thiol resin composition is used, there is a case where sufficient shear adhesive strength to the adherend cannot be obtained. Further, outgas may be generated not only from the resin composition in the middle of curing but also from the cured product, and the problem of outgas generation could not be completely solved.
Therefore, as a result of intensive studies, the present inventors have adjusted the storage elastic modulus of the ene-thiol resin composition to a specific range, thereby having high shear adhesive strength to the adherend and suppressing outgas generation. It has been found that a sealant for a display element can be obtained that is excellent in the transparency of the cured product, and the present invention has been completed.

The sealant for display element of the present invention comprises a polythiol compound having two or more thiol groups in one molecule (hereinafter also simply referred to as “polythiol compound”) and two or more carbon-carbon dicarbons in one molecule. It contains a polyene compound having a heavy bond (hereinafter also simply referred to as “polyene compound”). The sealing agent for display elements of the present invention containing these components is excellent in the transparency of the cured product and can suppress the generation of outgas.
In the present specification, the “carbon-carbon double bond” means an ethylenically unsaturated bond.

Examples of the polythiol compound include aliphatic polythiols such as ethanedithiol (molecular weight 94), propanedithiol (molecular weight 108), hexamethylenedithiol (molecular weight 150), decamethylenedithiol (molecular weight 206), and xylenedithiol (molecular weight 170). An aromatic polythiol such as the following, a cyclic sulfide compound such as a 1,4-dithiane ring-containing polythiol compound represented by the following formula (1), an ester bond-containing polythiol compound represented by the following formula (2), triglycol Examples include other polythiol compounds such as dimercaptan (molecular weight 182). These polythiol compounds may be used independently and may be used in combination of 2 or more type.

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

In the formula (2), R ¹ is an alkylene group having 1 to 12 carbon atoms, and R ² is an alkyl group having 1 to 12 carbon atoms. m is an integer of 0 to 2, n is an integer of 2 to 4, and n + m = 4.

Specific examples of the 1,4-dithiane ring-containing polythiol compound represented by the above formula (1) include 2,5-dimercaptomethyl-1,4-dithiane (molecular weight 212), 2,5-dithiane. Mercaptoethyl-1,4-dithiane (molecular weight 240), 2,5-dimercaptopropyl-1,4-dithiane (molecular weight 268), 2,5-dimercaptobutyl-1,4-dithiane (molecular weight 296), etc. Can be mentioned.

Among the polythiol compounds, since the obtained sealing agent for display elements is excellent in transparency, an ester bond-containing polythiol compound represented by the above formula (2) is preferable, and m in the above formula (2) is The compound which is 0 or 1 (n is 4 or 3) is more preferable.

Specific examples of the ester bond-containing polythiol compound represented by the above formula (2) include trimethylolpropane tris (3-mercaptopropionate) (molecular weight 398), tris ((3-mercaptopropionyloxy)- Ethyl) isocyanurate (molecular weight 526), pentaerythritol tetrakisthioglycolate (molecular weight 433), pentaerythritol tetrakis (3-mercaptopropionate) (molecular weight 489), tetraethylene glycol bis (3-mercaptopropionate) (molecular weight) 372).

The polythiol compound preferably has four or more thiol groups in one molecule because the obtained sealant for display elements has a high shear adhesive strength to the adherend.

Examples of the polythiol compound having 4 or more thiol groups in one molecule include dipentaerythritol hexakis (3-mercaptopropionate) (molecular weight 783), pentaerythritol tetrakisthioglycolate (molecular weight 433), pentaerythritol tetrakis. (3-mercaptopropionate) (molecular weight 489), tris [(3-mercaptopropionyloxy) -ethyl] isocyanurate (molecular weight 526) and the like. Among them, it is preferable to have 6 or more thiol groups in one molecule, and dipentaerythritol hexakis (3-mercaptopropionate) is more preferable.

The polythiol compound preferably has a molecular weight of 400 or more. By using a polythiol compound having a molecular weight of 400 or more, outgassing can be further suppressed. The minimum with more preferable molecular weight of the said polythiol compound is 500, and a still more preferable minimum is 600.
The preferred upper limit of the molecular weight of the polythiol compound is 6000. When the polythiol compound having a molecular weight exceeding 6000 is used, the obtained sealing agent for a display element may have a viscosity that is too high to be inferior in applicability. A more preferable upper limit of the molecular weight of the polythiol compound is 2000, and a more preferable upper limit is 1000.
In addition, when using an oligomer as the said polythiol compound or the said polyene compound, molecular weight may be represented using a weight average molecular weight.
In the present specification, the “weight average molecular weight” is a value determined by polystyrene conversion after measurement by gel permeation chromatography (GPC). Examples of the column used when measuring the weight average molecular weight in terms of polystyrene by GPC include Shodex LF-804 (manufactured by Showa Denko).

Examples of the polyene compound include allyl alcohol derivatives, esters obtained by reaction of (meth) acrylic acid and polyhydric alcohol, urethane acrylate, divinylbenzene (molecular weight 130), and the like. These polyene compounds may be used alone or in combination of two or more.
In the present specification, the “(meth) acryl” means acryl or methacryl.

Examples of the allyl alcohol derivatives include triallyl cyanurate (molecular weight 249), triallyl isocyanurate (molecular weight 249), diallyl maleate (molecular weight 196), diallyl adipate (molecular weight 226), diallyl phthalate (molecular weight 246), triaryl Allyl trimellitate (molecular weight 330), tetraallyl pyromellitate (molecular weight 414), glyceryl diallyl ether (molecular weight 172), trimethylolpropane diallyl ether (molecular weight 214), pentaerythritol diallyl ether (molecular weight 216), pentaerythritol triallyl And ether (molecular weight 256).

Examples of the esters obtained by the reaction of the (meth) acrylic acid and the polyhydric alcohol include, for example, ethylene glycol diacrylate (molecular weight 170), ethylene glycol dimethacrylate (molecular weight 198), propylene glycol diacrylate (molecular weight 185), Propylene glycol dimethacrylate (molecular weight 212), 1,4-butanediol diacrylate (molecular weight 198), 1,4-butanediol dimethacrylate (molecular weight 226), 1,6-hexanediol diacrylate (molecular weight 226), 1, 6-hexanediol dimethacrylate (molecular weight 254), glycerol triacrylate (molecular weight 254), glycerol trimethacrylate (molecular weight 296), trimethylolpropane triacrylate (molecular weight 296) , Trimethylolpropane trimethacrylate (molecular weight 338), pentaerythritol triacrylate (molecular weight 298), pentaerythritol trimethacrylate (molecular weight 340), pentaerythritol tetraacrylate (molecular weight 352), pentaerythritol tetramethacrylate (molecular weight 408), and the like. .

In addition, the polyene compound preferably has a cyclic structure because the obtained sealant for display elements has a high shear adhesive strength to the adherend.
The cyclic structure may be an aliphatic ring or an aromatic ring, but is preferably an aromatic ring because it is particularly excellent in the effect of improving the shear bond strength to the adherend. .

Examples of the polyene compound having a cyclic structure include divinylbenzene (molecular weight 130), triallyl cyanurate (molecular weight 249), triallyl isocyanurate (molecular weight 249), diallyl phthalate (molecular weight 246), and triallyl trimelli. Tate (molecular weight 330), tetraallyl pyromellitate (molecular weight 414), triallyl isocyanurate derivative (molecular weight 488) represented by the following formula (3), glycoluril derivative (molecular weight 330) represented by the following formula (4) ) And glycoluril derivatives (molecular weight 303) represented by the following formula (5).

Moreover, a polyene oligomer is also suitably used as the polyene compound.
Examples of the polyene monomer derived from the polyene oligomer include allyl alcohol derivatives, esters obtained by the reaction of (meth) acrylic acid and polyhydric alcohol, urethane acrylate, divinylbenzene and the like described above as the polyene compound.

Examples of the method for producing the polyene oligomer include a method of reacting the polyene monomer in the presence of an initiator such as benzoyl peroxide.

The polyene compound preferably has a molecular weight of 300 or more. By using a polyene compound having a molecular weight of 300 or more, outgassing can be further suppressed. The more preferable lower limit of the molecular weight of the polyene compound is 350, the more preferable lower limit is 400, and the particularly preferable lower limit is 500.
The preferred upper limit of the molecular weight of the polyene compound is 6000. When the polyene compound having a molecular weight exceeding 6000 is used, the obtained sealant for a display element may be too poor in applicability due to excessively high viscosity. A more preferable upper limit of the molecular weight of the polyene compound is 2000, and a more preferable upper limit is 1000.

The preferable lower limit of the content of the polyene compound in the total 100 parts by weight of the polythiol compound and the polyene compound or the total of 100 parts by weight of the polythiol compound, the polyene compound, and the thioether oligomer described later is 10 parts by weight, and the preferable upper limit is 70 Parts by weight. When the content of the polyene compound is less than 10 parts by weight, the obtained sealant for display element may be inferior in applicability. If the content of the polyene compound exceeds 70 parts by weight, the generation of outgas may not be sufficiently suppressed. A more preferable upper limit of the content of the polyene compound is 60 parts by weight, and a more preferable upper limit is 40 parts by weight.

The preferred lower limit of the number of moles of carbon-carbon double bonds in the polyene compound is 60% and the preferred upper limit is 150% with respect to the number of moles of thiol groups in the polythiol compound. If the number of moles of carbon-carbon double bonds in the polyene compound is less than 60% or more than 150%, generation of outgas may not be sufficiently suppressed. The number of moles of carbon-carbon double bonds in the polyene compound is more preferably a lower limit of 70%, more preferably an upper limit of 135%, and still more preferably a lower limit of 80%, relative to the number of moles of the thiol group of the polythiol compound. A preferable upper limit is 120%.

The sealing agent for display elements of this invention may contain the thioether oligomer formed by making a polythiol compound and a polyene compound react. By containing the thioether oligomer, the viscosity of the sealant for display elements is appropriately increased, and unevenness is less likely to occur during application.

The thioether oligomer can be added to both ends by heating the polythiol compound and an equimolar amount or an excess amount of the polyene compound with respect to the polythiol compound in the presence of a thermal polymerization initiator to cause an addition polymerization reaction. It is obtained in the reaction mixture as a polymer having a carbon-carbon double bond of a polyene compound.
The thioether oligomer may contain an unreacted thiol group or may not contain an unreacted thiol group. That is, it may be a thioether oligomer containing no thiol group obtained by sufficiently proceeding the addition polymerization reaction between the polythiol compound and the polyene compound, or obtained by stopping the reaction in the middle of the addition polymerization reaction. It may be a thioether oligomer containing an unreacted thiol group.

Examples of the thermal polymerization initiator used in the addition polymerization reaction between the polythiol compound and the polyene compound include a thermal radical polymerization initiator.
The said thermal radical polymerization initiator is not specifically limited, For example, what consists of an azo compound, an organic peroxide, etc. is mentioned.
Examples of the organic peroxide include benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, and peroxydicarbonate.
Examples of the azo compound include 2,2′-azobis (2,4-dimethylvaleronitrile), azobisisobutyronitrile, and the like.

In the above addition polymerization reaction between the polythiol compound and the polyene compound, when the number of moles of the thiol group of the polythiol compound relative to the number of moles of the carbon-carbon double bond of the polyene compound is 15% or less, the reaction mixture usually obtained The polyene compound remains as an unreacted component.

The minimum with a preferable weight average molecular weight of the said thioether oligomer is 500, and a preferable upper limit is 40,000. When the weight average molecular weight of the thioether oligomer is less than 500, the effect of preventing unevenness during application of the obtained sealant for display element may not be sufficiently exhibited. When the weight average molecular weight of the thioether oligomer is more than 40,000, the resulting sealant for display elements may have a too high viscosity and poor applicability. The minimum with a more preferable weight average molecular weight of the said thioether oligomer is 1000, and a more preferable upper limit is 10,000.

The minimum with preferable content of the said thioether oligomer in 100 weight part of total of a polythiol compound, a polyene compound, and a thioether oligomer is 20 weight part, and a preferable upper limit is 80 weight part. When the content of the thioether oligomer is less than 20 parts by weight, the effect of preventing unevenness during application of the obtained sealant for display element may not be sufficiently exhibited. When content of the said thioether oligomer exceeds 80 weight part, the viscosity of the sealing agent for display elements obtained will become high too much, and applicability | paintability may deteriorate. The minimum with more preferable content of the said thioether oligomer is 30 weight part, and a more preferable upper limit is 60 weight part.

The sealing agent for display elements of this invention may contain other curable resins other than the said polythiol compound and the said polyene compound.
The other curable resin is not particularly limited as long as it is cured by light or heat, and examples thereof include (meth) acrylic resins such as epoxy (meth) acrylate and urethane (meth) acrylate, and the polyene Non-compounds (monofunctional (meth) acryloyl group), epoxy resins, partial (meth) acryl-modified epoxy resins other than the above polyene compounds (monofunctional (meth) acryloyl group), etc. Is mentioned.
In the present specification, the “(meth) acrylate” means acrylate or methacrylate, and the “epoxy (meth) acrylate” means that all epoxy groups in the epoxy resin are reacted with (meth) acrylic acid. The “(meth) acrylic resin” means a resin having a (meth) acryloyl group, and the “(meth) acryloyl group” means an acryloyl group or a methacryloyl group. The “partially (meth) acryl-modified epoxy resin” is a resin having an epoxy group and an acryloyl group or a methacryloyl group in one molecule.

The sealing agent for display elements of this invention contains a photoinitiator.
The photopolymerization initiator preferably has a molecular weight of 220 to 1500. By using a photopolymerization initiator having a molecular weight of 220 to 1500, the sealant for display element of the present invention can suppress the generation of outgas. If the molecular weight of the photopolymerization initiator is less than 220, it may cause outgassing. When the molecular weight of the photopolymerization initiator exceeds 1500, it may be difficult to cure.
Among these, from the viewpoint of reducing the generation of outgas, the molecular weight is preferably 300 to 1000, and more preferably 350 to 700.

Examples of the photopolymerization initiator having a molecular weight of 220 to 1500 include compounds having an acylphosphine oxide skeleton, compounds having an α-aminoacetophenone skeleton, compounds having a benzyl ketal skeleton, compounds having an α-hydroxyacetophenone skeleton, benzoin Examples thereof include a compound having a skeleton, a compound having an oxime ester skeleton, a compound having a titanocene skeleton, an organic peroxide, an azo compound, and an oligomer compound. Among them, from the viewpoint of photocurability, a compound having an acylphosphine oxide skeleton, a compound having an α-aminoacetophenone skeleton, a compound having a benzyl ketal skeleton, a compound having an α-hydroxyacetophenone skeleton, a compound having a benzoin skeleton, and an oxime It is preferably at least one selected from the group consisting of a compound having an ester skeleton, a compound having a titanocene skeleton, and an oligomer compound. These photopolymerization initiators may be used alone or in combination of two or more.
Here, the compound having an acylphosphine oxide skeleton means a compound in which a part of the acylphosphine oxide is substituted with another group. The compound having the α-aminoacetophenone skeleton means a compound in which a part of α-aminoacetophenone is substituted with another group. The compound having a benzyl ketal skeleton means a compound in which a part of α-dihydroxyacetophenone is substituted with another group. The compound having the α-hydroxyacetophenone skeleton means a compound in which a part other than the hydroxyl group of α-monohydroxyacetophenone is substituted with another group. The compound having the benzoin skeleton means a compound in which a part of benzoin is substituted with another group. The compound having an oxime ester skeleton means a compound in which a part of N-acetyldimethyloxime is substituted with another group. The compound having a titanocene skeleton means a compound in which a part of titanocene is substituted with another group. The organic peroxide means a compound having a peroxy group. The azo compound means a compound having an azo group.

Examples of the compound having an acylphosphine oxide skeleton include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BASF Japan, “LUCILIN TPO”), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. ("BASF Japan," IRGACURE 819 ").

Examples of the compound having an α-aminoacetophenone skeleton include 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (manufactured by BASF Japan, “IRGACURE 907”), 2- Benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone (BASF manufactured by Japan, “IRGACURE 369”), 1,2- (dimethylamino) -2-((4-methylphenyl) methyl)- 1- (4- (4-morpholinyl) phenyl) -1-butanone (BASF Japan, “IRGACURE 379”) and the like.

Examples of the compound having a benzyl ketal skeleton include 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF Japan, “IRGACURE 651”).

Examples of the compound having an α-hydroxyacetophenone skeleton include 2-hydroxy-1- (4- (4- (2-hydroxy-2-methyl-propionyl) -benzyl) phenyl) -2-methyl-propane-1 -ON (BASF Japan, “IRGACURE 127”) and the like.

Examples of the compound having a benzoin skeleton include benzoin n-propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of the compound having an oxime ester skeleton include 1,2-octanedione-1- (4- (phenylthio) -2- (O-benzoyloxime)) (manufactured by BASF Japan, “IRGACURE OXE01”), ethanone -1- (9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl) -1- (0-acetyloxime) (manufactured by BASF Japan, “IRGACURE OXE02”) and the like.

Examples of the compound having a titanocene skeleton include bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium. (BASF Japan, “IRGACURE 784”).

The oligomer compound preferably has a polymerization degree of 2 to 10 from the viewpoint of reducing outgassing.
Specific examples include oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propane) (manufactured by Lamberti, “ESACURE KIP 150”, “ESCURE1”). .

Other examples of the photopolymerization initiator having a molecular weight of 220 to 1500 include 1- (4- (2-hydroxyethoxy) -phenyl) -2-hydroxy-2-methyl-1-propane-1- ON (manufactured by BASF Japan, “IRGACURE 2959” (molecular weight 224)), triphenyl phosphite and the like.

The lower limit of the content of the photopolymerization initiator is preferably 0.1 with respect to a total of 100 parts by weight of the polythiol compound and the polyene compound or a total of 100 parts by weight of the polythiol compound, the polyene compound, and the thioether oligomer. Part by weight, the preferred upper limit is 5 parts by weight. When the content of the photopolymerization initiator is less than 0.1 parts by weight, the photopolymerization of the obtained sealant for display elements may not sufficiently proceed. When the content of the photopolymerization initiator exceeds 5 parts by weight, the curing reaction becomes too fast, the workability is deteriorated, or the cured product of the obtained sealant for display elements is not uniform. There is. The minimum with more preferable content of the said photoinitiator is 0.3 weight part, and a more preferable upper limit is 3 weight part.

The sealant for display elements of the present invention may contain a thermal polymerization initiator.
As the thermal polymerization initiator, the same thermal polymerization initiator used for the addition polymerization reaction of the polythiol compound and the polyene compound can be used.

The sealant for display elements of the present invention may contain a thermosetting agent.
The said thermosetting agent will not be specifically limited if the hardened | cured material after hardening becomes transparent, For example, a thiol compound, an imidazole derivative, an amine compound, a polyhydric phenol type compound, an acid anhydride etc. are mentioned.

Examples of commercially available thermosetting agents include HN-2200, HN-2000, HN-5500, MHAC-P (all manufactured by Hitachi Chemical Co., Ltd.), Fuji Cure 7000, Fuji Cure 7001, Fuji Cure 7002, and Tomide. 410-N, tomide 215-70X, tomide 423, tomide 437, tomide TXC-636-A (all manufactured by T & K TOKA), MEH-8000H, MEH-8005 (all manufactured by Meiwa Kasei) and the like.

The sealant for display elements of the present invention may contain an adhesion promoter.
Examples of the adhesion-imparting agent include 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N- (aminoethyl) aminopropyltrimethoxy Examples include silane coupling agents such as silane and mercaptopropyltrimethoxysilane, titanium coupling agents, and aluminum coupling agents. These adhesiveness imparting agents may be used alone or in combination of two or more.

The sealing agent for display elements of the present invention may contain a stabilizer for the purpose of preventing oxidation or the like.
Examples of the stabilizer include 2,2′-methylenebis- (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (6-tert-butyl-3-methylphenol), 2,2 Examples include '-methylenebis- (4-ethyl-6-t-butylphenol). These stabilizers may be used independently and 2 or more types may be used together.

The sealant for display element of the present invention further includes a filler, a curing accelerator, a plasticizer, a surfactant, a flame retardant, an antistatic agent, an antifoaming agent, and a leveling agent as long as the object of the present invention is not impaired. In addition, an additive such as an ultraviolet absorber or an organic solvent may be contained, but from the viewpoint of ensuring transparency, it is preferable not to contain the filler.

As a method for producing the sealant for display element of the present invention, for example, a polythiol compound, a polyene compound, a photopolymerization initiator, and an adhesiveness-imparting agent that is added as necessary, using a stirrer. The method of mixing uniformly is mentioned.

The sealing agent for display elements of the present invention has a preferred lower limit of viscosity of 0.4 Pa · s and a preferred upper limit of 40 Pa · s measured using a cone rotor viscometer under the conditions of 20 ° C. and 20 rpm. When the viscosity is less than 0.4 Pa · s, composition unevenness occurs in the obtained sealant for display element, and the cured product may be inferior in transparency. When the viscosity exceeds 40 Pa · s, the application may be cut off during application. The more preferred lower limit of the viscosity is 0.5 Pa · s, the more preferred upper limit is 10 Pa · s, the still more preferred lower limit is 1 Pa · s, the still more preferred upper limit is 6 Pa · s, the particularly preferred lower limit is 2 Pa · s, and the particularly preferred upper limit is 4 Pa. -S.

The sealant for display elements of the present invention can be cured by light irradiation.
Examples of the method for photocuring the sealant for display elements of the present invention include 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 the sealing agent for display element of the present invention with light 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 lamp, and a microwave excitation mercury lamp. , 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 independently and 2 or more types may be used together.

Examples of light irradiation means for the sealant for display elements 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, etc. Irradiation means may be used.

In the sealant for display element of the present invention, the lower limit of the storage elastic modulus at 80 ° C. of the cured product is 70 MPa, and the upper limit is 1000 MPa. If the storage elastic modulus is outside this range, the shear bond strength to the adherend may be inferior, or generation of outgas due to the cured product may not be sufficiently suppressed. The preferable lower limit of the storage elastic modulus is 90 MPa, the preferable upper limit is 500 MPa, the more preferable lower limit is 100 MPa, the more preferable upper limit is 300 MPa, the still more preferable lower limit is 110 MPa, and the further preferable upper limit is 200 MPa.
In addition, the said storage elastic modulus can be measured by using a viscoelasticity measuring apparatus. Moreover, the hardened | cured material which measures the said storage elastic modulus can be produced by irradiating the sealing agent for display elements with 50 mW / cm < ² > ultraviolet-ray for 40 second.

As for the sealing agent for display elements of this invention, the minimum with the preferable glass transition temperature of hardened | cured material is 50 degreeC. If the glass transition temperature is less than 50 ° C., the shear bond strength to the adherend may be inferior, or generation of outgas due to the cured product may not be sufficiently suppressed. The minimum with said more preferable glass transition temperature is 65 degreeC.
In the present specification, the “glass transition temperature” means a temperature at which a maximum due to micro-Brownian motion appears in the maximum of loss tangent (tan δ) obtained by dynamic viscoelasticity measurement. The glass transition temperature can be measured by a conventionally known method using a viscoelasticity measuring device or the like. Moreover, the hardened | cured material which measures the said glass transition temperature can be produced by irradiating the ultraviolet ray of 50 mW / cm < ² > for 40 second to the sealing agent for display elements.

The preferable lower limit of the light transmittance at a wavelength of 380 to 780 nm of the cured product of the transparent sealing agent for display elements of the present invention is 85%. When the light transmittance is less than 85%, the transparency is inferior, and it may be unsuitable for use in sealing the entire surface of the display element. A more preferable lower limit of the light transmittance is 95%.
The light transmittance was obtained by producing a transmittance measurement sample by irradiating a transparent sealing agent for display element sandwiched between PET resin films with 50 mW / cm ² of ultraviolet light for 40 seconds. The transmittance measurement sample can be measured using a spectrophotometer.

The sealing agent for display elements of this invention is used in order to seal the surface of a display element, the whole surface, a front surface, a rear surface, or the circumference | surroundings. Among these, it is preferably used for sealing the entire surface of the display element. In the present specification, the “entire surface” does not necessarily mean 100% of the surface of the display element, but means a necessary sealing surface required for the display element. The “front surface” means a surface from which light is extracted, that is, a surface on the viewing side.

The sealant for display elements of the present invention can be used, for example, as a sealant for organic EL display elements, a sealant for liquid crystal display elements, a sealant for electrochromic substrates, a sealant for electronic paper, and the like. .

ADVANTAGE OF THE INVENTION According to this invention, it has high shear adhesive strength with respect to a to-be-adhered body, can suppress generation | occurrence | production of outgas, and provides the sealing agent for display elements which is excellent in transparency of hardened | cured material. it can.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Preparation of thioether oligomer A)
As a thermal polymerization initiator, dipentaerythritol hexakis (60 parts by weight of 3-mercaptopropionate) as a polythiol compound and 40 parts by weight of a glycoluril derivative represented by the above formula (4) as a polyene compound are heated and stirred. 0.2 part by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) is gradually added, the resulting reaction mixture is poured into a poor solvent, the precipitated oligomer is collected, and the solvent is removed under vacuum. As a result, thioether oligomer A was obtained.
For the obtained thioether oligomer A, the weight average molecular weight in terms of polystyrene was measured by gel permeation chromatography (GPC) using Shodex LF-804 (manufactured by Showa Denko KK) as a column. As a result, the weight average molecular weight of the thioether oligomer A was 4000.
The measurement by GPC was performed under a temperature condition of 40 ° C. by flowing 50 μL of a tetrahydrofuran solution containing 0.5% by weight of thioether oligomer A at a flow rate of 1 mL / min.

(Preparation of thioether oligomer B)
A weight average molecular weight of 2000 is the same as that of “(Preparation of thioether oligomer A)” except that the amount of 2,2′-azobis (2,4-dimethylvaleronitrile) added is changed to 0.05 parts by weight. The thioether oligomer B was obtained.

(Preparation of condensate A)
After 180 parts by weight of 3-mercaptopropyltrimethoxysilane was stirred and mixed with 49.6 parts by weight of ion-exchanged water and 9 parts by weight of a formic acid aqueous solution having a concentration of 95% by weight at room temperature for 30 minutes, toluene 272 A part by weight was added and a condensation reaction was carried out by heating at 75 ° C. for 60 minutes. After the reaction, the pressure was reduced and the remaining portion was distilled off to obtain a condensate A having two or more thiol groups in one molecule.
The resulting condensate A had a weight average molecular weight of 1500 and a thiol equivalent of 136 g / eq.

(Preparation of condensate B)
After 190 parts by weight of 3-mercaptopropyltrimethoxysilane was mixed with 52 parts by weight of ion-exchanged water and 9.5 parts by weight of a formic acid aqueous solution having a concentration of 95% by weight at room temperature for 30 minutes, a hydrolysis reaction was performed. A part by weight was added and a condensation reaction was carried out by heating at 75 ° C. for 60 minutes. After the reaction, the pressure was reduced and the remaining portion was distilled off to obtain a condensate B having two or more thiol groups in one molecule.
The obtained condensate B had a weight average molecular weight of 5000 and a thiol equivalent of 398 g / eq.

(Examples 1 to 11, Comparative Examples 1 to 9)
According to the mixing ratios described in Tables 1 and 2, each material was mixed using a stirrer (manufactured by Shinto Kagaku Co., Ltd., “Three-One Motor HEIDON BLH300”), whereby Examples 1 to 11 and Comparative Examples 1 to Nine display element sealants were prepared.

<Evaluation>
About each sealing agent for display elements obtained by the Example and the comparative example, it evaluated by the following method. The results are shown in Tables 1 and 2.

(1) Storage elastic modulus Each sealant for display elements obtained in Examples and Comparative Examples was put into a Teflon (registered trademark) length 35 mm, width 3 mm, thickness 1 mm mold, and a high pressure mercury lamp was used. A sample for viscoelasticity measurement having a length of 35 mm, a width of 3 mm, and a thickness of 1 mm was produced by irradiating with 50 mW / cm ² of ultraviolet rays for 40 seconds. About the obtained viscoelasticity measurement sample, using a dynamic viscoelasticity measurement device (IT Measurement Control Co., Ltd., “DVA-200”), the dynamic viscoelasticity was measured under the conditions of 0 to 100 ° C. and 10 Hz, The storage elastic modulus at 80 ° C. was measured.

(2) Viscosity for each display element obtained in Examples and Comparative Examples using a viscosity cone rotor viscometer (“TV-22 type” manufactured by Toki Sangyo Co., Ltd.) under the conditions of 20 ° C. and 20 rpm. The viscosity of was measured.

(3) The applicability at the time of apply | coating the sealing agent for each display element obtained by the Example and the comparative example on the glass substrate using the applicability | distribution dispenser (the Musashi engineering company make, "SHOTMASTER300") was evaluated. . When the dispense nozzle is 400 μm, the nozzle gap is 30 μm, and the coating pressure is fixed at 300 kPa, it can be applied without fading or sagging. “○○”, when it can be applied with almost no fading or sagging. The coating property was evaluated as “△” when there was no clear coating or sagging, but “×” when large coating failure or coating unevenness occurred, or when the coating could not be applied at all.

(4) Glass transition temperature Each sealant for display elements obtained in Examples 1 to 8, 10, and 11 and Comparative Examples 1 to 3 to 7 was irradiated with ultraviolet rays of 50 mW / cm ² for 40 seconds using a high pressure mercury lamp. Irradiation was performed to prepare a sample for measuring viscoelasticity having a length of 35 mm, a width of 3 mm, and a thickness of 1 mm. For the obtained sample, the dynamic viscoelasticity was measured at 0 to 100 ° C. and 10 Hz using a dynamic viscoelasticity measuring apparatus (“DVA-200” manufactured by IT Measurement Control Co., Ltd.), and the loss tangent (tan δ) was measured. The maximum temperature was determined as the glass transition temperature (Tg).

(5) Outgas generation amount Each sealant for display elements obtained in the examples and comparative examples was applied using a bar coater so that the thickness after application was 100 μm, and 50 mW / A film was formed by irradiation with ultraviolet rays of cm ² for 40 seconds.
Using a thermal analyzer (“TG / DTA6200” manufactured by Seiko Instruments, Inc.), the resulting film was measured for weight loss rate when heated to 150 ° C. at a rate of temperature increase of 10 ° C./min, and this was generated as outgas. The amount.

(6) Shear adhesive strength Each sealant for display elements obtained in Examples and Comparative Examples contains a resin spacer (Sekisui Chemical Co., Ltd., “Micropearl SP-205”) having an average particle diameter of 0 μm. After mixing to 1 wt% and applying to one of two glass plates (length 45 mm, width 25 mm), the other glass plate was stacked and bonded together, and 50 mW / cm ² using a high pressure mercury lamp. Was irradiated for 40 seconds to prepare a sample for a shear bond strength test. About the obtained sample for shear bond strength tests, the tensile test was done at a speed | rate of 5 mm / min using autograph AGS1000D (made by Shimadzu Corp.), and the shear bond strength was measured. The shear bond strength was evaluated by assuming that the shear bond strength was 3 MPa or more as “◯”, 2 MPa or more and less than 3 MPa as “Δ”, and less than 2 MPa as “X”.

(7) Transparency of cured product (light transmittance)
Each sealant for display elements obtained in Examples and Comparative Examples is sandwiched between PET resin films and irradiated with 50 mW / cm ² ultraviolet ray for 40 seconds using a high-pressure mercury lamp, for measuring transmittance of 100 μm in thickness. A sample was made. The obtained transmittance measurement sample was measured for light transmittance at a wavelength of 380 to 780 nm using a spectrophotometer (manufactured by Hitachi, Ltd., “U-3000”, conditions 300 to 800 nm).

(8) Display performance of display element (8-1) Display performance of liquid crystal display element (production of liquid crystal display element)
Prepare two glass substrates (length 25mm, width 25mm, thickness 0.7mm) on which an ITO electrode with a thickness of 1000mm is formed on the surface and then an orientation film with a thickness of 800mm is applied on the surface by spin coating. Then, using a thermosetting epoxy resin (peripheral sealant) on one substrate, printing of a pattern in which a liquid crystal injection port was provided was performed by screen printing. Next, the substrate on which the pattern was printed was kept at 80 ° C. for 3 minutes to perform preliminary drying and fusion of the peripheral sealant to the substrate, and then returned to room temperature. Next, after spraying a spacer of 5 μm on the other substrate, each substrate was bonded, and the peripheral sealant was cured by hot pressing heated to 130 ° C. for 2 hours to obtain an empty cell. . The obtained empty cell was vacuum-sucked, and then liquid crystal (“ZLI-479232” manufactured by Merck & Co., Inc.) was injected from the injection port. The injection port was sealed in each display element obtained in Examples and Comparative Examples. Then, the sealing agent was cured by irradiating with 50 mW / cm ² of ultraviolet rays for 40 seconds using a high-pressure mercury lamp. Thereafter, the liquid crystal was annealed at 120 ° C. for 1 hour to produce a liquid crystal display element.

(Liquid crystal orientation disorder)
The obtained liquid crystal display element was driven in a halftone display state at a voltage of AC 3.5 V, and the alignment disorder of the liquid crystal near the inlet was observed with a polarizing microscope. "○" when no orientation disorder is confirmed, "○" when slight orientation disorder less than 0.3 mm is confirmed, "△" when less than 1 mm orientation disorder is confirmed, "1" or more The display performance of the liquid crystal display element was evaluated with “×” when there was a clear alignment disorder (dark color unevenness).
In addition, liquid crystal display elements with an evaluation of “XX” or “O” are at a level where there is no problem in practical use, and “△” is a level that may cause a problem depending on the display design of the liquid crystal display element. , “×” is a level that cannot withstand practical use.

(8-2) Display performance of organic EL display device (production of a substrate on which a laminate including an organic light emitting material layer is disposed)
A glass substrate (length 25 mm, width 25 mm, thickness 0.7 mm) on which an ITO electrode was formed to a thickness of 1000 mm was used as the substrate. The substrate was ultrasonically washed with acetone, an aqueous alkali solution, ion-exchanged water, and isopropyl alcohol for 15 minutes, respectively, then washed with boiled isopropyl alcohol for 10 minutes, and a UV-ozone cleaner (manufactured by Nippon Laser Electronics Co., Ltd.). The last treatment was performed with “NL-UV253”).
Next, this substrate is fixed to the substrate folder of the vacuum deposition apparatus, and 200 mg of N, N′-di (1-naphthyl) -N, N′-diphenylbenzidine (α-NPD) is put into an unglazed crucible and other different types. 200 mg of tris (8-hydroxyquinola) aluminum (Alq ₃ ) was put in an unglazed crucible, and the pressure in the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. Thereafter, the crucible containing α-NPD was heated, and α-NPD was deposited on the substrate at a deposition rate of 15 ｓ / s to form a 600 正孔 hole transport layer. Next, the crucible containing Alq ₃ was heated to form an organic light emitting material layer having a thickness of 600 で 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 vapor deposition apparatus, and 200 mg of lithium fluoride is added to a tungsten resistance heating boat in the vacuum vapor deposition apparatus, and aluminum is added to another tungsten boat. 1.0 g of wire was added. After that, the inside of the vapor deposition unit of the vacuum vapor deposition apparatus is depressurized to 2 × 10 ⁻⁴ Pa to form a lithium fluoride film with a thickness of 5 mm at a deposition rate of 0.2 kg / s, and then aluminum with a film thickness of 1000 mm at a rate of 20 kg / s. did. The inside of the vapor deposition apparatus was returned to normal pressure with nitrogen, and the substrate on which the laminate including the organic light emitting material layer of 10 mm × 10 mm was arranged was taken out.

(Coating with inorganic material film A)
A mask having an opening of 13 mm × 13 mm is installed so as to cover the entire laminate of the substrate on which the laminate including the obtained organic light emitting material layer is disposed, and the inorganic material film A is formed by plasma CVD. Formed.
In the plasma CVD method, SiH ₄ gas and nitrogen gas are used as source gases, the flow rates are 10 sccm and 200 sccm, RF power is 10 W (frequency: 2.45 GHz), chamber temperature is 100 ° C., and chamber pressure is 0. The test was performed at 9 Torr.
The formed inorganic material film A had a thickness of about 0.2 μm.

(Formation of resin protective film)
In the vacuum apparatus, a substrate on which the laminate coated with the inorganic material film A is disposed is installed, and each display element seal obtained in the examples and comparative examples is placed on a heating boat installed in the vacuum apparatus. 0.5 g of the agent is added, the pressure is reduced to 10 Pa, and the sealant for display element is heated at 200 ° C. to the 11 mm × 11 mm square portion including the laminate so that the thickness becomes 0.5 μm. Vacuum deposition was performed. Thereafter, ultraviolet rays of 50 mW / cm ² were irradiated for 40 seconds using a high pressure mercury lamp in a vacuum environment to cure the display element sealant to form a resin protective film.

(Coating with inorganic material film B)
A mask having an opening of 12 mm × 12 mm is installed so as to cover the entire 11 mm × 11 mm resin protective film of the substrate on which the resin protective film is formed, and an inorganic material film B is formed by plasma CVD and displayed. An element (organic EL display element) was obtained.
In the plasma CVD method, SiH ₄ gas and nitrogen gas are used as source gases, the flow rates of each are SiH ₄ gas 10 sccm, nitrogen gas 200 sccm, RF power 10 W (frequency 2.45 GHz), chamber temperature 100 ° C., chamber The test was performed under the condition that the internal pressure was 0.9 Torr. The formed inorganic material film B had a thickness of about 1 μm.

(Light emission state of organic EL display element)
The prepared organic EL display elements were exposed for 100 hours under conditions of 60 ° C. and 90% RH, respectively, and then a voltage of 3 V was applied, and the light emission state (light emission and dark spots, presence / absence of pixel peripheral quenching) was visually observed. , “○○” when emitting light uniformly without dark spots or peripheral quenching, a slight decrease in brightness is seen, “○” when emitting light uniformly without dark spots or peripheral quenching, partially dark The case where there was a spot or slight peripheral quenching was evaluated as “Δ”, and the case where there was a dark spot in a wide range or there was significant peripheral quenching was evaluated as “x”.

Claims

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,
A sealant for display elements, wherein the cured product has a storage elastic modulus at 80 ° C. of 70 to 1000 MPa.
The glass transition temperature of hardened | cured material is 50 degreeC or more, The sealing compound for display elements of Claim 1 characterized by the above-mentioned.
The sealing agent for display elements according to claim 1, wherein the polythiol compound has a molecular weight of 400 or more.
4. The sealant for a display element according to claim 1, wherein the polythiol compound has four or more thiol groups in one molecule.
The sealing agent for a display element according to claim 1, 2, 3, or 4, wherein the polyene compound has a molecular weight of 300 or more.
6. The sealant for a display element according to claim 1, wherein the polyene compound has a cyclic structure.
The sealant for a display element according to claim 1, comprising a thioether oligomer.
8. The viscosity measured at 20 ° C. and 20 rpm using a cone rotor viscometer is 0.4 to 40 Pa · s, wherein the viscosity is 0.4 to 40 Pa · s. Sealant for display element.