JP4528358B2 - Sealant for liquid crystal dropping method and liquid crystal display element - Google Patents

Description

The present invention stably manufactures a liquid crystal display element without being accidentally cured even when it is exposed to weak light that is not intended to cure the sealing agent at the time of manufacturing a liquid crystal display element by a liquid crystal dropping method. The present invention relates to a sealing agent for liquid crystal dropping method. Moreover, this invention relates to the liquid crystal display element which uses this sealing compound for liquid crystal dropping methods.

In recent years, a method for manufacturing a liquid crystal display element such as a liquid crystal display cell has been in the direction of adopting a liquid crystal dropping method in place of a conventional vacuum injection method from the viewpoint of shortening tact time and optimizing the amount of liquid crystal used.
For the production of a liquid crystal display element by a liquid crystal dropping method, for example, from a photothermosetting resin composition containing a photocurable acrylic resin and a photopolymerization initiator, and a thermosetting epoxy resin and a thermopolymerization initiator. A liquid crystal dropping method sealing agent (hereinafter also simply referred to as “sealing agent”) is used.

In the liquid crystal dropping method, first, a seal pattern is formed on one of two transparent substrates with electrodes by screen printing. Next, fine droplets of liquid crystal are dropped onto the entire surface of the transparent substrate in a state where the sealant is uncured, the other transparent substrate is immediately overlaid, and the seal portion is irradiated with ultraviolet rays for temporary curing. Thereafter, heating is performed during liquid crystal annealing to perform main curing, thereby obtaining a liquid crystal display element. If the substrates are bonded together under reduced pressure, a liquid crystal display element can be manufactured with extremely high efficiency (for example, Patent Documents 1 and 2).

In recent years, mobile devices with various liquid crystal panels such as mobile phones and portable game machines are rapidly spreading, and liquid crystal display elements are also required to be downsized. As a means for downsizing the liquid crystal display element, there is a narrow frame of the liquid crystal display unit.
Along with the narrowing of the frame of the liquid crystal display part, the place where the sealing agent is arranged in the panel is also limited, and even if the ultraviolet ray is irradiated to cure the sealing agent, there may be a place where the ultraviolet ray is not irradiated. . For example, a portion where ultraviolet rays of several tens to several hundreds of μm are not irradiated is generated under the wiring of the array.

Thus, in order to surely cure even when there is a portion not irradiated with ultraviolet rays, for example, a method of increasing the blending amount of the ultraviolet curing component in the sealing agent (for example, Patent Document 3) or a large absorption wavelength at 350 nm Attempts have been made to improve ultraviolet curability, such as a method of blending a UV radical initiator. These methods are extremely effective in terms of reliable ultraviolet curing.

However, if a sealant with improved UV curable properties is used, the sealant may be accidentally cured by the interior lighting of the work room or the illumination of various devices in the process prior to the UV irradiation process, which is originally intended to be cured. There was a problem that there was. This problem is most likely to occur when there is a weak light source for alignment in the substrate bonding step in which oxygen having a polymerization inhibiting action is extremely reduced. In particular, when the blending amount of the ultraviolet curing component is large as in the sealing agent described in Patent Document 3, the rate of occurrence of erroneous curing increases dramatically.

JP 2001-133794 A JP-A-5-295087 JP 2006-313289 A

The present invention stably manufactures a liquid crystal display element without being accidentally cured even when it is exposed to weak light that is not intended to cure the sealing agent at the time of manufacturing a liquid crystal display element by a liquid crystal dropping method. It aims at providing the sealing compound for liquid crystal dropping methods which can be performed. Moreover, an object of this invention is to provide the liquid crystal display element which uses this sealing compound for liquid crystal dropping methods.

The present invention is a liquid crystal dropping method sealant containing a curable resin, a UV radical initiator and a radical polymerization inhibitor, wherein the curable resin comprises a curable resin having a (meth) acryl group and an epoxy group. And the ratio of the (meth) acrylic group to the epoxy group is 60:40 to 95: 5, and the UV radical initiator is measured at 350 nm measured in acetonitrile. For liquid crystal dropping method having an extinction coefficient of 500 ml · g ⁻¹ · cm ⁻¹ or more and a blending amount of the radical polymerization inhibitor of 0.1 to 0.4 parts by weight with respect to 100 parts by weight of the curable resin. It is a sealing agent.
The present invention is described in detail below.

The present inventors include a curable resin having a high content ratio of (meth) acrylic groups and a high reactivity of radical reaction, and a UV radical initiator having a high reactivity, so that a portion where ultraviolet rays are not irradiated is present. By adding a specific amount of radical polymerization inhibitor to the sealing agent with improved UV curable properties so that it can be reliably cured even in some cases, it is exposed to weak light that is not intended to cure the sealing agent. The present inventors have found that a sealing agent capable of stably producing a liquid crystal display element can be obtained without being accidentally cured even if there is a case, and the present invention has been completed.

The sealing agent of the present invention contains a curable resin.
The curable resin is one in which a curable resin having a (meth) acryl group and a curable resin having an epoxy group coexist.

The curable resin having the (meth) acrylic group is not particularly limited. For example, an ester compound obtained by reacting a (meth) acrylic acid with a compound having a hydroxyl group, (meth) acrylic acid and an epoxy compound are reacted. Epoxy (meth) acrylate obtained by making it react, urethane (meth) acrylate obtained by making the (meth) acrylic acid derivative which has a hydroxyl group react with isocyanate, etc. are mentioned.

The ester compound obtained by reacting the above (meth) acrylic acid with a compound having a hydroxyl group is not particularly limited, and examples of monofunctional compounds include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ) Acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) ) Acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxyethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, Lahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, methoxy polyethylene glycol (meta ) Acrylate, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 1H, 1H, 5H-octafluoropentyl (meth) acrylate, imide (meth) ) Acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, cyclo Xyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) ) Acrylate, bicyclopentenyl (meth) acrylate, isodecyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyl Roxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl 2-hydroxypropyl phthalate, glycidyl (meth) acrylate, 2- (meth) acryloyloxyethyl phosphate, etc. The

Examples of the bifunctional ester compound obtained by reacting the above (meth) acrylic acid with a compound having a hydroxyl group include 1,4-butanediol di (meth) acrylate and 1,3-butanediol di (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate 2-n-butyl-2-ethyl- 1,3-propanediol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) Acrylate, tetrae Lenglycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene oxide added bisphenol A type di (meth) acrylate, ethylene oxide added bisphenol A type di (meth) acrylate, ethylene oxide added bisphenol F type di (meth) acrylate, Dimethylol dicyclopentadienyl di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide modified isocyanuric acid di (meth) acrylate, 2-hydroxy-3- (Meth) acryloyloxypropyl (meth) acrylate, carbonate diol di (meth) acrylate, polyether diol di (meth) acrylate, polyester dio Di (meth) acrylate, polycaprolactone diol di (meth) acrylate, polybutadiene di (meth) acrylate.

Among the ester compounds obtained by reacting the above (meth) acrylic acid with a compound having a hydroxyl group, those having three or more functional groups include, for example, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, propylene Oxide-added trimethylolpropane tri (meth) acrylate, ethylene oxide-added trimethylolpropane tri (meth) acrylate, caprolactone-modified trimethylolpropane tri (meth) acrylate, ethylene oxide-added isocyanuric acid tri (meth) acrylate, dipentaerythritol penta (meth) Acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra ( Data) acrylate, glycerin tri (meth) acrylate, propylene oxide addition glycerin tri (meth) acrylate, tris (meth) acryloyloxyethyl phosphate, and the like.

The epoxy (meth) acrylate obtained by reacting the (meth) acrylic acid and the epoxy compound is not particularly limited. For example, an epoxy resin and (meth) acrylic acid are combined in the presence of a basic catalyst according to a conventional method. And the like obtained by reacting with.

The epoxy compound used as a raw material for synthesizing the epoxy (meth) acrylate is not particularly limited. Examples of commercially available products include bisphenol A such as Epicoat 828EL and Epicoat 1004 (both manufactured by Japan Epoxy Resin Co., Ltd.). Type epoxy resin, bisphenol F type epoxy resin such as Epicoat 806 and Epicoat 4004 (both made by Japan Epoxy Resin), bisphenol S type epoxy resin such as Epicron EXA1514 (made by DIC), and RE-810NM (Nipponization) 2,2'-diallyl bisphenol A type epoxy resin such as Yakuhin), hydrogenated bisphenol type epoxy resin such as Epicron EXA7015 (made by DIC), and propylene oxide-added bisphenol such as EP-4000S (made by ADEKA) A-type epoxy resin, resorcinol-type epoxy resin such as EX-201 (manufactured by Nagase ChemteX), biphenyl-type epoxy resin such as Epicoat YX-4000H (made by Japan Epoxy Resin), YSLV-50TE (Toto Kasei) ), Epoxy ether resins such as YSLV-80DE (manufactured by Toto Kasei), dicyclopentadiene epoxy resins such as EP-4088S (ADEKA), Epicron HP4032, and Epicron. Naphthalene type epoxy resin such as EXA-4700 (all made by DIC), phenol novolac type epoxy resin such as Epicron N-770 (made by DIC), Epicron N-670-EXP-S (made by DIC), etc. Orthocresol novolac type epoxy resin, Dicyclopentadiene novolac type epoxy resin such as Piclon HP7200 (manufactured by DIC), biphenyl novolac type epoxy resin such as NC-3000P (manufactured by Nippon Kayaku Co., Ltd.), and naphthalene phenol such as ESN-165S (manufactured by Tohto Kasei Co., Ltd.) Novolak type epoxy resin, Glycidylamine type epoxy resin such as Epicoat 630 (manufactured by Japan Epoxy Resin), Epicron 430 (manufactured by DIC), TETRAD-X (manufactured by Mitsubishi Gas Chemical Company), ZX-1542 (Tohto Kasei Co., Ltd.) ), Epicron 726 (manufactured by DIC), Epolite 80MFA (manufactured by Kyoeisha Chemical Co., Ltd.), Denacol EX-611, (manufactured by Nagase ChemteX), YR-450, YR-207 (any) Also manufactured by Toto Kasei Co., Ltd.), Epolide PB (Daisei) Bisphenol A-type episulfide resins such as rubber-modified epoxy resins such as Le Chemical Co., Ltd., glycidyl ester compounds such as Denacol EX-147 (manufactured by Nagase ChemteX), and Epicoat YL-7000 (manufactured by Japan Epoxy Resin Co., Ltd.) YDC-1312, YSLV-80XY, YSLV-90CR (all manufactured by Tohto Kasei Co., Ltd.), XAC4151 (manufactured by Asahi Kasei Co., Ltd.), Epicoat 1031, Epicoat 1032 (all manufactured by Japan Epoxy Resin Co., Ltd.), EXA-7120 (DIC) ), TEPIC (Nissan Chemical Co., Ltd.) and the like.

Specifically, the epoxy (meth) acrylate obtained by reacting the (meth) acrylic acid and the epoxy compound is, for example, 360 parts by weight of EX-201 (manufactured by Nagase ChemteX Corporation) as a resorcinol type epoxy resin. Obtained by reacting 2 parts by weight of p-methoxyphenol as a polymerization inhibitor, 2 parts by weight of triethylamine as a reaction catalyst, and 210 parts by weight of acrylic acid for 5 hours while stirring and refluxing at 90 ° C. Can do.

Examples of commercially available epoxy (meth) acrylates include, for example, Eveacryl 3700, Evekril 3600, Evekril 3701, Evekril 3703, Evekrill 3200, Evekrill 3201, Evekril 3600, Evekril 3702, Evekril 3412, Evekril 860, Evekril RDX63182 , Evecri 6040, Evekril 3800 (all manufactured by Daicel Cytec), EA-1020, EA-1010, EA-5520, EA-5323, EA-CHD, EMA-1020 (all manufactured by Shin-Nakamura Chemical Co., Ltd.), epoxy Ester M-600A, Epoxy ester 40EM, Epoxy ester 70PA, Epoxy ester 200PA, Epoxy ester 80MFA, Epoxy ester 3002M, Poxy ester 3002A, Epoxy ester 1600A, Epoxy ester 3000M, Epoxy ester 3000A, Epoxy ester 200EA, Epoxy ester 400EA (all manufactured by Kyoeisha Chemical Co., Ltd.), Denacol acrylate DA-141, Denacol acrylate DA-314, Denacol acrylate DA -911 (all manufactured by Nagase ChemteX Corporation).

The urethane (meth) acrylate obtained by reacting the isocyanate with a (meth) acrylic acid derivative having a hydroxyl group is, for example, a (meth) acrylic acid derivative 2 having a hydroxyl group with respect to 1 equivalent of a compound having two isocyanate groups. The equivalent weight can be obtained by reacting in the presence of a catalytic amount of a tin-based compound.

Isocyanate that is a raw material of urethane (meth) acrylate obtained by reacting a hydroxyl group-containing (meth) acrylic acid derivative with the isocyanate is not particularly limited. For example, isophorone diisocyanate, 2,4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4′-diisocyanate (MDI), hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene Range Iocyanate (XDI), Hydrogenated XDI, Lysine Diisocyanate, Triphenylmethane Triisocyanate, Tris (Isocyanate Phenyl) Thioff Sufeto, tetramethyl xylene diisocyanate, 1,6,10- undecene country isocyanate.

Isocyanate which is a raw material of urethane (meth) acrylate obtained by reacting a hydroxyl group-containing (meth) acrylic acid derivative with the isocyanate is not particularly limited. For example, ethylene glycol, glycerin, sorbitol, trimethylolpropane, (poly ) Chain-extended isocyanate compounds obtained by reaction of polyols such as propylene glycol, carbonate diol, polyether diol, polyester diol, polycaprolactone diol and excess isocyanate can also be used.

The (meth) acrylic acid derivative having a hydroxyl group, which is a raw material for urethane (meth) acrylate obtained by reacting the isocyanate with a (meth) acrylic acid derivative having a hydroxyl group, is not particularly limited. For example, 2-hydroxyethyl Commercial products such as (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ethylene glycol, propylene glycol, 1,3-propanediol, 1 Mono (meth) acrylates of divalent alcohols such as 1,3-butanediol, 1,4-butanediol and polyethylene glycol, mono (meth) acrylates of trivalent alcohols such as trimethylolethane, trimethylolpropane and glycerin, or (Meth) acrylates, epoxy acrylates such as bisphenol A-modified epoxy acrylate.

Specifically, the urethane (meth) acrylate obtained by reacting the isocyanate with a (meth) acrylic acid derivative having a hydroxyl group includes, for example, 134 parts by weight of trimethylolpropane and 0.2 part by weight of BHT as a polymerization inhibitor. And 0.01 parts by weight of dibutyltin dilaurate as a reaction catalyst and 666 parts by weight of isophorone diisocyanate are reacted at 60 ° C. with stirring under reflux for 2 hours, and then 51 parts by weight of 2-hydroxyethyl acrylate is added. It can be obtained by reacting for 2 hours at 90 ° C. while refluxing while feeding air.

Examples of commercially available urethane (meth) acrylates include M-1100, M-1200, M-1210, and M-1600 (all manufactured by Toagosei Co., Ltd.), Evekril 230, Evekril 270, and Evekril 4858. , Evekril 8402, Evekrill 8804, Evekrill 8803, Evekrill 8807, Evekrill 9260, Evekrill 1290, Evekril 5129, Evekril 4842, Evekril 4827, Evekril 6700, Evekril 220, Evekyle Rine Tech Co., Ltd. UN-9000H, Art Resin UN-9000A, Art Resin UN-7100, Art Resin UN-1255, Art Resin UN-330, Art Resin UN-332 HB, Art Resin UN-1200TPK, Art Resin SH-500B (all manufactured by Negami Kogyo Co., Ltd.), U-122P, U-108A, U-340P, U-4HA, U-6HA, U-324A, U-15HA, UA-5201P, UA-W2A, U-1084A, U-6LPA, U-2HA, U-2PHA, UA-4100, UA-7100, UA-4200, UA-4400, UA-340P, U-3HA, UA- 7200, U-2061BA, U-10H, U-122A, U-340A, U-108, U-6H, UA-4000 (all manufactured by Shin-Nakamura Chemical Co., Ltd.), AH-600, AT-600, UA- 306H, AI-600, UA-101T, UA-101I, UA-306T, UA-306I, and the like.

The curable resin having the (meth) acryl group is preferably one having a hydrogen bonding unit such as —OH group, —NH— group, —NH ₂ group, etc. in terms of suppressing adverse effects on the liquid crystal. Epoxy (meth) acrylate is particularly preferred from the standpoint of ease.

The curable resin having the (meth) acryl group is preferably one having 2 to 3 (meth) acryl groups in the molecule because of its high reactivity.

Moreover, it is preferable that the reactive functional group is an acryl group from the high reactivity of the curable resin which has the said (meth) acryl group.

The epoxy resin-containing curable resin is not particularly limited. Examples of commercially available resins include bisphenol A type epoxy resins such as Epicoat 828EL and Epicoat 1004 (all manufactured by Japan Epoxy Resin Co., Ltd.), Epicoat 806, 2, such as bisphenol F type epoxy resin such as Epicoat 4004 (all made by Japan Epoxy Resin), bisphenol S type epoxy resin such as Epicron EXA1514 (made by DIC), RE-810NM (made by Nippon Kayaku) 2'-diallyl bisphenol A type epoxy resin, hydrogenated bisphenol type epoxy resin such as Epicron EXA7015 (manufactured by DIC), propylene oxide-added bisphenol A type epoxy resin such as EP-4000S (manufactured by ADEKA), EX- 201 Resorcinol type epoxy resin such as Sechemtex), biphenyl type epoxy resin such as Epicoat YX-4000H (Japan Epoxy Resin), sulfide type epoxy resin such as YSLV-50TE (manufactured by Toto Kasei), YSLV- Ether type epoxy resin such as 80DE (manufactured by Toto Kasei), dicyclopentadiene type epoxy resin such as EP-4088S (manufactured by ADEKA), naphthalene such as epicron HP4032, epicron EXA-4700 (all manufactured by DIC) Type epoxy resin, phenol novolac type epoxy resin such as Epicron N-770 (manufactured by DIC), orthocresol novolak type epoxy resin such as Epicron N-670-EXP-S (manufactured by DIC), and Epicron HP7200 (DIC) Etc.) Cyclopentadiene novolac type epoxy resin; biphenyl novolac type epoxy resin such as NC-3000P (manufactured by Nippon Kayaku Co., Ltd.), naphthalene phenol novolac type epoxy resin such as ESN-165S (manufactured by Tohto Kasei Co., Ltd.), Epicoat 630 (Japan epoxy) Resin), Epicron 430 (DIC), TETRAD-X (Mitsubishi Gas Chemical) and other glycidylamine type epoxy resins, ZX-1542 (Toto Kasei), Epicron 726 (DIC), Alkyl polyol type epoxy resins such as Epolite 80MFA (manufactured by Kyoeisha Chemical Co., Ltd.), Denacol EX-611, (manufactured by Nagase ChemteX Corporation), YR-450, YR-207 (both manufactured by Tohto Kasei Co., Ltd.), Epolide PB (Daicel) Rubber-modified epoxy resins such as Glycidyl ester compounds such as Denacol EX-147 (manufactured by Nagase ChemteX), bisphenol A type episulfide resins such as Epicoat YL-7000 (manufactured by Japan Epoxy Resin), and other YDC-1312, YSLV-80XY, YSLV-90CR (All manufactured by Tohto Kasei Co., Ltd.), XAC4151 (manufactured by Asahi Kasei Co., Ltd.), Epicoat 1031, Epicote 1032 (all manufactured by Japan Epoxy Resin Co., Ltd.), EXA-7120 (manufactured by DIC), TEPIC (manufactured by Nissan Chemical Co., Ltd.) and the like. It is done.

The curable resin having an epoxy group may be, for example, a compound having a (meth) acryl group and an epoxy group in one molecule. As such a compound, for example, a compound obtained by reacting a part of an epoxy group of a compound having two or more epoxy groups with (meth) acrylic acid, and the like can be mentioned.

The compound obtained by reacting a part of the epoxy groups having two or more epoxy groups with (meth) acrylic acid is prepared by, for example, reacting an epoxy resin and (meth) acrylic acid with a basic catalyst according to a conventional method. It is obtained by reacting in the presence. Specifically, for example, 190 g of phenol novolac type epoxy resin N-770 (manufactured by DIC) is dissolved in 500 mL of toluene, 0.1 g of triphenylphosphine is added to this solution to obtain a uniform solution, and acrylic acid is added to this solution. 36 g was added dropwise over 2 hours under reflux stirring, and further reflux stirring was performed for 6 hours. Next, by removing toluene, a novolac-type solid modified epoxy resin in which 50 mol% of epoxy groups reacted with acrylic acid was obtained. Yes (in this case 50% partially acrylated).

Of the compounds obtained by reacting a part of the epoxy groups having two or more epoxy groups with (meth) acrylic acid, a commercially available product is, for example, UVAC 1561 (manufactured by Daicel Cytec Co., Ltd.).

The ratio of (meth) acrylic group to epoxy group in the curable resin is 60:40 to 95: 5. When the ratio of the (meth) acrylic group is less than 60 mol%, the curing component with ultraviolet rays is reduced to cause display unevenness, or the portion not irradiated with ultraviolet rays cannot be sufficiently cured. When the ratio of the (meth) acrylic group exceeds 95 mol%, the adhesive strength decreases. The preferable lower limit of the ratio of the (meth) acrylic group is 65 mol%, the more preferable lower limit of the ratio of the (meth) acrylic group is 70 mol%, and the more preferable lower limit is 80 mol%.

The sealing agent for liquid crystal dropping method of the present invention contains a UV radical initiator.
The UV radical initiator has an extinction coefficient at 350 nm measured in acetonitrile of 500 ml · g ⁻¹ · cm ⁻¹ or more. Such a UV radical initiator has high reactivity, and when used in combination with the above curable resin, the sealing agent for liquid crystal dropping method of the present invention can be reliably cured even when there is a portion not irradiated with ultraviolet rays. it can. If the extinction coefficient is less than 500 ml · g ⁻¹ · cm ⁻¹ , display unevenness occurs, or a portion that is not irradiated with ultraviolet rays cannot be sufficiently cured. A preferable upper limit of the extinction coefficient is 30000 ml · g ⁻¹ · cm ⁻¹ .

Examples of commercially available UV radical initiators include Irgacure 907 (1520 ml · g ⁻¹ · cm ⁻¹ ), Irgacure 819 (3200 ml · g ⁻¹ · cm ⁻¹ ), Irgacure 651 (820 ml · g ^-1 · ^{cm -1),} Irgacure ^{369 (23000ml · g -1 · cm} -1), Irgacure ^{379 (20500ml · g -1 · cm} -1), Irgacure ^{OXE01 (18000ml · g -1 · cm} -1) , Irgacure 1300 (9800 ml · g ⁻¹ · cm ⁻¹ ), Irgacure 1800 (3100 ml · g ⁻¹ · cm ⁻¹ ), Irgacure 1870 (3600 ml · g ⁻¹ · cm ⁻¹ ), Irgacure 4265 (550 ml · g ^{− 1} · ^{cm -1),} Irgacure 784 (2200 ^{l · g -1 · cm -1)} , Irgacure ^{OXE02 (27000ml · g -1 · cm} -1), ( all manufactured by Ciba Japan), benzoin methyl ether ^{(970ml · g -1 · cm -1} ) , Benzoin ethyl ether (990 ml · g ⁻¹ · cm ⁻¹ ), benzoin isopropyl ether (1020 ml · g ⁻¹ · cm ⁻¹ ), lucillin TPO (850 ml · g ⁻¹ · cm ⁻¹ ) (manufactured by BASF Japan) Etc. The numerical value in parentheses represents the extinction coefficient at 350 nm measured in acetonitrile.

Although content of the said UV radical initiator is not specifically limited, A preferable minimum is 0.1 weight part and a preferable upper limit is 10 weight part with respect to 100 weight part of resin which has the said (meth) acryl group. When the content of the UV radical initiator is less than 0.1 parts by weight, the liquid crystal dropping method sealing agent of the present invention may not be sufficiently cured. When content of the said UV radical initiator exceeds 10 weight part, storage stability may fall.

The sealing agent for liquid crystal dropping method of the present invention contains a radical polymerization inhibitor.
Examples of the radical polymerization inhibitor include 2,6-di-t-butylcresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl β- (3,5-di-). t-butyl-4-hydroxyphenyl) propionate, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4 '-Thiobis-3-methyl-6-t-butylphenol), 4,4-butylidenebis (3-methyl-6-t-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- ( 3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxaspiro [5,5] undecane, tetraki -[Methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, 1,3,5-tris (3', 5'-di-t-butyl-4 '-Hydroxybenzyl) -sec-triazine-2,4,6- (1H, 3H, 5H) trione, hydroxyl, paramethoxyphenol and the like. These radical polymerization inhibitors may be used alone or in combination of two or more.

The blending amount of the radical polymerization inhibitor is such that the lower limit is 0.1 parts by weight and the upper limit is 0.4 parts by weight with respect to 100 parts by weight of the curable resin. When the blending amount of the radical polymerization inhibitor is less than 0.1 parts by weight, the radical polymerization inhibitor is quickly consumed by radicals generated slightly when weak light is present during the production of the liquid crystal display element. In other words, when it is exposed to weak light that is not intended to cure the sealant, it is accidentally cured. When the blending amount of the radical polymerization inhibitor exceeds 0.4 parts by weight, the ultraviolet curing property of the obtained sealing agent is remarkably lowered, and it may not be cured even when irradiated with ultraviolet rays for the purpose of curing the sealing agent.
In addition, although the said radical polymerization inhibitor is mix | blended also at the synthesis | combination stage of the said curable resin which has the (meth) acryl group, the compounding quantity is with respect to 100 weight part of curable resin which has a (meth) acryl group normally. It is about 0.05 part by weight, and hardly remains in the final sealant.

The sealing agent for liquid crystal dropping method of the present invention preferably further contains a thermal epoxy curing agent.
The said thermal epoxy hardening | curing agent is not specifically limited, For example, organic acid hydrazide, an imidazole derivative, an amine compound, a polyhydric phenol type compound, an acid anhydride etc. are mentioned. Among these, solid organic acid hydrazide is preferable.

The solid organic acid hydrazide is not particularly limited. For example, sebacic acid dihydrazide, isophthalic acid dihydrazide, adipic acid dihydrazide, others, Amicure VDH, Amicure VDH-J, Amicure UDH, Amicure UDH-J (all of which are Ajinomoto Fine Techno) And ADH (manufactured by Otsuka Chemical Co., Ltd.).

Although content of the said thermal epoxy hardening | curing agent is not specifically limited, A preferable minimum is 1 weight part and a preferable upper limit is 50 weight part with respect to 100 weight part of curable resin which has the said epoxy group. When the content of the thermal epoxy curing agent is less than 1 part by weight, the liquid crystal dropping method sealing agent of the present invention may not be sufficiently cured. When the content of the thermal epoxy curing agent exceeds 50 parts by weight, the viscosity of the sealing agent for liquid crystal dropping method of the present invention is increased, and the coating property and the like may be impaired. The upper limit with more preferable content of the said thermal epoxy hardening | curing agent is 30 weight part.

The sealing agent for liquid crystal dropping method of the present invention preferably further contains a silane coupling agent.
As the silane coupling agent, for example, γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane and the like are preferably used.

The sealing agent for liquid crystal dropping method of the present invention preferably contains a filler for the purpose of improving the adhesiveness by the stress dispersion effect, improving the linear expansion coefficient, and the like.
Examples of the filler include talc, asbestos, silica, diatomaceous earth, smectite, bentonite, calcium carbonate, magnesium carbonate, alumina, montmorillonite, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, magnesium hydroxide, and aluminum hydroxide. Inorganic fillers such as silicon nitride, barium sulfate, gypsum, calcium silicate, glass beads, sericite activated clay, and aluminum nitride, and organic fillers such as polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and acrylic polymer fine particles .

The liquid crystal dropping method sealing agent of the present invention further includes a reactive diluent for adjusting the viscosity, a thixotropic agent for adjusting thixotropy, a spacer such as polymer beads for adjusting the panel gap, if necessary, It may contain a curing accelerator such as P-chlorophenyl-1,1-dimethylurea, an antifoaming agent, a leveling agent, a thermal radical initiator, and the like.

The sealing agent for liquid crystal dropping method of the present invention preferably contains as little solvent as possible in the sealing agent, and of course, the viscosity of the sealing agent is temporarily increased during the sealing agent manufacturing process as well as not mixing the solvent as a blend. It is not preferable to mix a solvent for the purpose of lowering.

The liquid crystal dropping method sealing agent of the present invention is produced by mixing the curable resin having the (meth) acrylic group, a UV radical initiator, a radical polymerization inhibitor, and an additive to be blended as necessary. can do. At this time, it is preferable to carry out the production under conditions where radicals are unlikely to be generated so as not to consume a small amount of the incorporated radical polymerization inhibitor. For example, when mixing using a ball mill, a large amount of radicals may be generated. On the other hand, generation of radicals can be suppressed by using a planetary stirrer (for example, manufactured by Shinky Co., Ltd., Awatori Nertaro series).

The liquid crystal display element manufactured using the sealing agent for liquid crystal dropping methods of this invention is also one of this invention.

According to the present invention, when a liquid crystal display element is manufactured by a liquid crystal dropping method, the liquid crystal display element can be stably cured without being erroneously cured even when exposed to weak light that is not intended to cure the sealant. It is possible to provide a sealant for a liquid crystal dropping method capable of producing a liquid crystal. Moreover, according to this invention, the liquid crystal display element which uses this sealing compound for liquid crystal dropping methods can be provided.

It is a schematic diagram explaining the light-shielding part sclerosis | hardenability evaluation method performed in the Example.

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

(Synthesis of epoxy acrylate (EX-201 acrylic modified product))
111 g of EX-201 (resorcinol type epoxy resin) was dissolved in 500 mL of toluene, and 0.1 g of triphenylphosphine was added thereto to obtain a uniform solution. To this solution, 72 g of acrylic acid was added dropwise over 2 hours with stirring under reflux, followed by further stirring under reflux for 8 hours.
Next, by removing toluene, an epoxy acrylate (EX-201 acrylic modified product) in which all epoxy groups were converted to acrylic groups was synthesized.

(Synthesis of epoxy methacrylate (EX-201 methacrylic modified product))
111 g of EX-201 (resorcinol type epoxy resin) was dissolved in 500 mL of toluene, and 0.1 g of triphenylphosphine was added thereto to obtain a uniform solution. To this solution, 85 g of methacrylic acid was added dropwise over 2 hours with stirring under reflux, followed by further stirring under reflux for 8 hours.
Next, by removing toluene, an epoxy acrylate (EX-201 methacryl-modified product) in which all epoxy groups were converted to acrylic groups was synthesized.

(Synthesis of partially acrylated epoxy acrylate (N-770 partially acryl modified product))
190 g of N-770 (phenol novolac type epoxy resin) is dissolved in 500 mL of toluene, 0.1 g of triphenylphosphine is added to this solution to obtain a uniform solution, and 36 g of acrylic acid is added dropwise to the solution over 2 hours with stirring under reflux. Thereafter, the mixture was further stirred under reflux for 6 hours, and then toluene was removed to obtain a partially acrylated epoxy acrylate (N-770 partially acrylic modified product) in which 50 mol% of the epoxy group was modified with an acrylic group.

(Examples 1-7 and Comparative Examples 1-7)
In accordance with the blending ratios described in Tables 1 and 2, each material was mixed using a planetary stirrer (manufactured by Sinky Corporation, “Awatori Nertaro”), and then further mixed using three rolls. The sealing agent for liquid crystal dropping methods of 1-7 and Comparative Examples 1-7 was prepared.

Note that the UV radical initiator used in Examples and Comparative Examples, the measured extinction coefficient at 350nm in acetonitrile, Irgacure 184 350ml ^· g ^{-1 · cm} -1, Irgacure 651 820 ml · ^{g -1} · cm ⁻¹ and Irgacure 819 were 3200 ml · g ⁻¹ · cm ⁻¹ .

(Evaluation)
The sealing agents for liquid crystal dropping gazettes obtained in Examples and Comparative Examples were evaluated by the following methods.
The results are shown in Tables 1 and 2.

(1) Evaluation of panel color unevenness The obtained sealing agent for liquid crystal dropping method was drawn on a substrate on which a black matrix (BM) and a transparent electrode were formed with a dispenser so as to draw a frame. Subsequently, fine droplets of liquid crystal (manufactured by Chisso Corporation, “JC-5004LA”) were dropped onto the entire surface of the substrate frame, and another substrate with a transparent electrode (without BM) was immediately overlaid. At this time, the drawing was performed so that the line width of the crushed sealant was about 1.2 mm, and 0.3 mm of the sealant overlapped with BM.

After that, the sealing material is thermally cured by irradiating UV light at 100 mW / cm ² for 30 seconds from the substrate side on which the BM is formed using 100 mW / cm ² and further performing liquid crystal annealing at 120 ° C. for 1 hour. Thus, an element for liquid crystal display was obtained.
For the obtained liquid crystal display panel, visually observe the color unevenness that occurs in the vicinity of the seal part. If there is no color unevenness, “◎”, if there is almost no color unevenness, “○”, if there is a little color unevenness. The case where there was considerable “Δ” and uneven color was evaluated as “x” in four stages.
The above observation was performed in a state where no power was supplied (non-lighting) and a state where power was supplied (lighting).

(2) Adhesive strength 3 parts by weight of polymer beads having an average particle diameter of 5 μm (“Micropearl SP”, manufactured by Sekisui Chemical Co., Ltd.) are dispersed by a planetary stirrer with respect to 100 parts by weight of the obtained liquid crystal dropping method sealing agent. To obtain a uniform solution. A very small amount of the obtained liquid was placed in the center of a glass substrate Corning 1737 (20 mm × 50 mm × 0.7 mmt), and the same type of glass substrate was overlaid thereon to spread the liquid crystal dropping method sealant. In that state, 100 mW / cm ² of ultraviolet rays were irradiated for 30 seconds. Then, it heated at 120 degreeC for 1 hour, and obtained the adhesion test piece. About the obtained test piece, the adhesive strength was measured using the tension gauge (comparative unit: N / cm < ² >).

(3) Light Stability Evaluation The obtained sealing agent for liquid crystal dropping method was applied in a spot shape on a slide glass, placed in a glass transparent vacuum desiccator and left under a fluorescent lamp in a vacuum state of 3 torr.
After being left for 5, 20, and 60 minutes, a glass slide not coated with a liquid crystal dropping method sealant was bonded to a predetermined gap distance. At this time, whether or not the applied sealing agent for the liquid crystal dropping method was crushed was visually observed, and the case where it was crushed was evaluated as “◯”, and the case where it was not crushed was evaluated as “x”.

(4) Evaluation of light-shielding part curability A substrate 1 having chromium deposited on one half of a 0.7 mm thick Corning glass and a substrate 2 having chromium deposited on the front surface were prepared (FIG. 1A).
The sealing agent for liquid crystal dropping method was applied to the boundary portion between the portion where the chromium deposition was performed on the substrate 1 and the portion where the chromium deposition was not performed, and the substrate 2 was bonded together and then sufficiently crushed. As a result, the sealing agent for the liquid crystal dropping method spread widely on the substrate (FIG. 1B).

The bonded substrate was irradiated with ultraviolet light at 100 mW / cm ² for 30 seconds from the surface of the substrate 1 (FIG. 1B). Thereafter, the substrate 1 and the substrate 2 are broken, and chromium deposition is performed from the boundary between the portion directly irradiated with ultraviolet rays (the location 1, the portion not covered with chromium deposition) and the portion not subjected to chromium deposition. The sealant on the spot (place 2), the spot 200 μm (place 3), and the spot (place 4) containing 300 μm in the applied part was collected (FIG. 1 (c)). The spectrum of the collected sealant was measured by a microscopic IR method, and the conversion rate of the (meth) acryl functional group in the sealant was determined from each spectrum. The peak area of 810 m ⁻¹ was used for quantification of the (meth) acryl functional group.

According to the present invention, when a liquid crystal display element is manufactured by a liquid crystal dropping method, the liquid crystal display element can be stably cured without being erroneously cured even when exposed to weak light that is not intended to cure the sealant. It is possible to provide a sealant for a liquid crystal dropping method capable of producing a liquid crystal. Moreover, according to this invention, the liquid crystal display element which uses this sealing compound for liquid crystal dropping methods can be provided.

Claims (3)

A sealing agent for liquid crystal dropping method containing a curable resin, a UV radical initiator and a radical polymerization inhibitor,
The curable resin is one in which a curable resin having a (meth) acryl group and a curable resin having an epoxy group coexist, and the ratio of the (meth) acryl group to the epoxy group is from 60:40 to 95: 5,
The UV radical initiator has an extinction coefficient at 350 nm measured in acetonitrile of 500 ml · g ⁻¹ · cm ⁻¹ or more,
The sealing agent for liquid crystal dropping method, wherein the amount of the radical polymerization inhibitor is 0.1 to 0.4 parts by weight with respect to 100 parts by weight of the curable resin. The sealing agent for liquid crystal dropping method according to claim 1, wherein the (meth) acrylic group is an acrylic group. A liquid crystal display element manufactured using the sealing agent for liquid crystal dropping method according to claim 1.

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