JP2020506255A - Radiation curable sealant composition - Google Patents

Abstract

Disclosed are radiation curable sealant compositions that are particularly suited for the manufacture of liquid crystal displays. The sealant composition comprises one or more curable resins having a group selected from an epoxy group, a (meth) acryloyl group, a maleimide group, and combinations thereof, and a latent curing agent. The molar equivalent ratio of the maleimide group to the (meth) acryloyl group and / or epoxy group in the curable resin is more than 0.2. The radiation curable sealant composition has excellent gel time under UV curing, improved resistance to liquid crystal penetration and liquid crystal contamination, good adhesion, and good reliability.

Description

  The present invention relates to radiation-curable sealant compositions. Specifically, the present invention relates to radiation curable sealant compositions having excellent gel time, improved resistance to liquid crystal penetration and liquid crystal contamination, good adhesion, and good reliability. Specifically, the radiation-curable sealant composition is suitable for use in a one-drop-fill (ODF) method of manufacturing a liquid crystal display (LCD).

  2. Description of the Related Art Liquid crystal display (LCD) panels having features of being lightweight and having high definition are widely used as display panels for various devices including mobile phones and TVs. Conventionally, a method for manufacturing an LCD panel includes applying a sealant on a substrate having an electrode pattern and an alignment film under vacuum conditions, and dropping liquid crystal (LC) on the substrate having the applied sealant thereon. The opposing substrates are bonded together under vacuum, then the vacuum is released and pure ultraviolet (UV) radiation, pure heating, or a combination of UV radiation and heating is performed to cure the sealant, thereby It is referred to as the one drop fill (ODF) method, which involves making LCD cells.

  Recently, the development of LCDs has been moving towards "slim border" or "narrow bezel" designs. One of several ways to achieve this goal is the use of narrow width sealants. However, due to the fact that the ODF method must meet very high reliability in order to prevent leakage, misalignment and contamination of the liquid crystal material, the typical ODF method requires a narrower sealant line width, More challenges arise.

  Further, in the ordinary ODF method, radiation curing such as UV curing, and heat curing are used to cure the sealant alone or in combination. Ultraviolet rays can be emitted from the color filter side and the array side of the cell. 2. Description of the Related Art In recent years, the frame of an LCD unit has been narrowed due to miniaturization of a device including an LCD such as a mobile phone or a portable game machine. Therefore, the sealant pattern formed on the base material is often arranged at a position overlapping the black matrix. This can be problematic because the overlapping portions of the sealant on the black matrix remain uncured and flowable even after UV irradiation. Uncured sealant readily elutes from the overlap into the liquid crystal, causing LC contamination.

  On the other hand, it is conceivable to irradiate UV light from the array side, but metal wiring and transistors on the array base material overlap with the sealant pattern to form a shadow area, whereby uncured portions of the sealant elute from the sealant. The problem still remains, as it can be more prone to "shadow cure" problems such as contact with the LC and causing LC contamination.

  Attempts have been made to improve the shadow curing problem and avoid LC contamination for the ODF process by using a pure heat curing process or a combination of a heat curing process and an irradiation curing process.

  For example, US 200796056 A1 discloses the use of thiol compounds as chain transfer agents in curable sealant compositions to improve the shadow curability of cured products obtained in ODF processes including UV curing and thermal curing. Has been disclosed.

  CN 10167267 A discloses the use of both a thermal radical polymerization initiator and a thiol chain transfer agent in a curable sealant composition for the ODF method, whereby the curability in the light-shielded area is improved, and It is described that excellent seal quality can be obtained.

  Japanese Patent No. 3977747 discloses a sealant composition for an ODF method comprising an acrylated epoxy, an amine, a thiol, a gelling agent, and a thixotrope, wherein the sealant composition has a thixotropy index (TI) of 1 .2 to 2 are disclosed.

  CN 101952852 A contains a sealant composition for an ODF method, comprising an epoxy and a latent curing agent, having a gel time of less than 3 minutes at 100 ° C., and achieving good sealing shape stability and a long pot life. Is disclosed.

Japanese Patent No. 5597338 discloses a sealant composition for an ODF method comprising an alkoxysilyl group-modified epoxy resin, a radical polymerizable resin, and a latent curing agent. A sealant composition for the ODF process is disclosed which is in the range of 1000 to 100000 Pa · s after 20 minutes at 100 ° C. or after illumination of 100 mW / cm ² and UV irradiation of 1000 mJ / cm ² .

US 2007096056 A1 CN 10167267 A Japanese Patent No. 3976749 CN 101952852 A Japanese Patent No. 5597338

  However, concerns about LC contamination and / or shadow curability remain with prior art ODF process sealant compositions. Accordingly, there remains a need for radiation curable sealant compositions that can at least partially solve the problem and maintain an excellent adhesive performance profile.

  The present invention provides radiation curable sealant compositions suitable for ODF processes, particularly ODF processes that include one or more UV curing steps. We have found that the radiation curable sealant composition of the present invention contributes to improved gel time, excellent LC penetration of the cured sealant product and resistance to contamination. Specifically, the radiation-curable sealant composition comprises at least one curable resin having a group selected from an epoxy group, a (meth) acryloyl group, a maleimide group and a combination thereof, and a latent curing agent. The molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups in one or more curable resins is greater than about 0.2.

The present invention also provides
1) a step of applying the radiation-curable sealant composition of the present invention to a sealing region at a peripheral portion of the surface of the first base material;
2) performing radiation curing of the radiation-curable sealant composition to obtain a partially cured product;
3) a step of forming a liquid crystal layer by dropping liquid crystal on a central area surrounded by a sealing area on the surface of the first base material or on a corresponding area of the second base material;
4) laminating the first and second substrates; and 5) performing a thermal cure of the partially cured product, between the first and second substrates. A method for manufacturing a liquid crystal display having a liquid crystal layer is also provided.

Hereinafter, the present invention will be described in more detail.
Each aspect so described can be combined with any other aspect, unless expressly stated otherwise. In particular, any feature described as preferred or advantageous may be combined with any other feature or features described as preferred or advantageous.

  In this specification, the terms used should be interpreted according to the following definitions unless otherwise specified.

  As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

  The terms “comprising,” “including,” and “including” as used herein are synonymous with “include,” “include,” or “containing,” “containing.” Yes, comprehensive or open-ended and does not exclude additional unlisted elements, components or process steps.

  The recitation of numerical endpoints includes not only the stated endpoint, but also all numbers and fractions subsumed within each respective range.

  All references cited herein are hereby incorporated by reference in their entirety.

  Unless defined otherwise, all terms used herein, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. By further guidance, term definitions are included to better understand the teachings of the present invention.

  In one aspect, the present invention provides a radiation curable composition comprising one or more curable resins having a group selected from an epoxy group, a (meth) acryloyl group, a maleimide group, and combinations thereof, and a latent curing agent. A radiation-curable sealant composition, wherein the molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups in one or more curable resins is greater than about 0.2. .

Curable resin The curable resin contained in the sealant composition of the present invention has at least two groups selected from a maleimide resin, an epoxy resin, a (meth) acrylate resin, a maleimide group, an epoxy group, and a (meth) acryloyl group. It may be selected from hybrid resins, as well as mixtures thereof. However, the molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups in one or more curable resins is greater than about 0.2, preferably about 0.25 to about 10, more preferably about 0. 0.3 to about 5.0.

  In one embodiment, the curable resin contained in the sealant is a combination of a maleimide resin and an epoxy resin, or a combination of a maleimide resin and a (meth) acrylate resin.

Maleimide resin In the present invention, one or more, preferably one or two, moieties (I) in the molecule:
A resin having a partial structure represented by and having essentially no or no (meth) acryloyl group and epoxy group is referred to as a maleimide resin. R ¹ and R ² are H or a C _1-6 alkyl group, or R ¹ and R ² together become a C _2-6 alkylene group. Preferably, both R ¹ and R ² represent H, or R ¹ and R ² together represent a 1,4-butylene group.

  The maleimide resin is preferably liquid at room temperature, so that moiety (I) has a group that allows the maleimide resin to be liquid, for example, a length and branches sufficient to make the maleimide resin liquid, It is attached to an organic group containing a branched alkyl, alkylene, alkylene oxide, alkylenecarboxyl or alkyleneamide structure. The maleimide resin may include one or more partial structures (I). The compound having two of these groups is a bismaleimide compound. Further, the maleimide compound is not necessarily a liquid, but may be used when it is mixed with another maleimide compound or when mixed with other components to make the sealant composition liquid.

Maleimide compounds in which moiety (I) is bonded to an alkyl or alkylene group (these groups can include a double bond and a saturated alicyclic) include the following compounds.

  Particularly preferred examples include stearyl maleimide, oleyl maleimide, behenyl maleimide, and X-BMI (X-bismaleimide; formulas (X-1) to (X-4)) commercially available from Henkel Corporation and combinations thereof. No. X-BMI is derived from 1,20-diamino-10,11-dioctyleicosane and / or its cyclic isomer diamine in U.S. Pat. No. 5,973,166 (disclosed in U.S. Pat. No. 5,973,166). (Incorporated herein by reference). X-BMI is 1,20-bismaleimide-10,11-dioctyleicosane [resin represented by the formula (X-1)], 1-heptylenemaleimido-2-octylenemaleimido-4-octyl-5. -Heptylcyclohexane [resin represented by formula (X-2)], 1,2-dioctylenemaleimido-3-octyl-4-hexylcyclohexane [resin represented by formula (X-3)], 4,5- One or two or more such as dioctylene maleimide-1,2-diheptylcyclohexene [resin represented by the formula (X-4)] is included. The bismaleimide resins represented by the formulas (X-1) to (X-4) may be used alone, and are preferred.

Epoxy Resin In the present invention, a radiation curable resin having an epoxy group and having essentially no or no (meth) acryloyl group and maleimide group is referred to as an epoxy resin. The epoxy resins of the present invention also include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin; novolak type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin. Resin; Biphenyl type epoxy resin; Hydrogenated bisphenol type epoxy resin (Bisphenol A type epoxy resin, Bisphenol F type epoxy resin, Bisphenol type epoxy resin such as bisphenol S type epoxy resin with hydrogenated benzene ring); Dicyclopentadiene type epoxy resins such as glycidyl ether of dicyclopentadiene phenol novolak; and cyclohexane dimethanol diglycidyl ether It may include Ruarayuru epoxy resin, but is not limited thereto.

  A suitable commercially available epoxy resin used in the present invention is, for example, a bisphenol A type epoxy resin JER YL 980 manufactured by Mitsubishi Chemical Corporation.

  The epoxy resin preferably has a molecular weight such that the resin becomes a liquid. The epoxy resin is preferably liquid and has a viscosity at 25 ° C in the range of about 1,000 to about 1,000,000 cps, and more preferably has a viscosity in the range of about 2,000 to about 700,000 cps.

(Meth) acrylate resin In the present invention, it has a (meth) acryloyl group, particularly a (meth) acrylate group (that is, a (meth) acryloyloxy group), and has essentially no or no epoxy group and maleimide group. The radiation-curable resin that is not used is referred to as a (meth) acrylate resin. The term (meth) acryloyl refers to both the commonly used acryloyl and methacryloyl. The same applies to (meth) acrylate and the like. (Meth) acrylate resins suitable for use in radiation-curable resins include ester compounds obtained by the reaction of (meth) acrylic acid with a compound having a hydroxyl group, and the reaction of (meth) acrylic acid with an epoxy compound. (Meth) acrylates obtained by the method described above, and urethane (meth) acrylates obtained by reacting isocyanates with (meth) acrylic acid derivatives having hydroxyl groups, and mixtures or combinations thereof. .

  The ester compound obtained by reacting (meth) acrylic acid with a compound having a hydroxyl group is not particularly limited. Examples of the ester compound having one functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, isobutyl (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, and imide (meth) acrylate , Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. But not limited to these. Examples of ester compounds having two functional groups include, but are not limited to, 1,6-hexanediol di (meth) acrylate and 1,9-nonanediol di (meth) acrylate. Examples of the ester compound having three or more functional groups include pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, and the like.

  Epoxy (meth) acrylates are also suitable in the present invention, which are obtained by the reaction of (meth) acrylic acid with an epoxy compound, have one or more (meth) acrylate groups, and are substantially free of epoxy groups. It is a derivative of epoxy resin that does not have. According to the invention, epoxy (meth) acrylate refers to a specific type of (meth) acrylate resin, not an epoxy resin. Examples include epoxy (meth) acrylates obtained by reacting an epoxy resin with (meth) acrylic acid in the presence of a basic catalyst according to methods known in the art. Preferably, the epoxy (meth) acrylate is a fully (meth) acrylated epoxy in which nearly 100% of the epoxy groups can be converted to (meth) acrylic groups.

  Examples of commercially available epoxy (meth) acrylates include Ebecryl 3708, Ebecryl 3600, Ebecryl 3701, Ebecryl 3703, Ebecryl 3200, Ebecryl 3201, Ebecryl 3600, Ebecryl 3702, Ebecryl 3412, Ebecryl 860, Ebecryl RDX63182, Ebecryl 6040 3800 (all manufactured by Cytec Industries, Inc.), EA-1020, EA-1010, EA-5520, EA-5323, EA-CHD, EMA-1020 (all manufactured by Shin-Nakamura Chemical Co., Ltd.) It is not limited to.

  The urethane (meth) acrylate obtained by the reaction of an isocyanate with a (meth) acrylic acid derivative having a hydroxyl group has one equivalent of a compound having two isocyanate groups and a hydroxyl group (meth) in the presence of a catalytic amount of a tin compound. ) Acrylic acid derivative can be obtained by reacting with 2 equivalents.

  Examples of commercially available urethane (meth) acrylates are M-1100, M-1200, M-1210, M-1600 (all manufactured by Toagosei Co., Ltd.), Ebecryl 230, Ebecryl 270, Ebecryl 4858, Ebecryl 8402, Ebecryl 8804, Ebecryl 8803, Ebecryl 8807, Ebecryl 9260, Ebecryl 1290, Ebecryl 5129, Ebecryl 4842, Ebecryl 210, Ebecryl 4827, Ebecryl 6700, Ebecryl 220, Ebecryl 2220 (all manufactured by Daicel Ornex), Art Resin UN-9000H, Art Resin Including UN-9000A, Art Resin UN-7100, Art Resin UN-1255, Art Resin UN-330, Art Resin UN-3320HB, Art Resin UN-1200TPK, Art Resin SH-500B (all manufactured by Negami Industry Co., Ltd.) However, it is not limited to these.

Hybrid Resin In the present invention, a resin having a maleimide group and one or more groups selected from an epoxy group and a (meth) acryloyl group is referred to as a hybrid resin. Preferably, the hybrid resin has a maleimide group and a group selected from a (meth) acryloyl group and a maleimide group at a molecular terminal.

  The main chain of the hybrid resin has many types such as a bisphenol A main chain, a dicyclopentadiene-based main chain, a resorcil diglycidyl ether-based main chain, an isocyanurated main chain, and the like, and the terminal functional group has It may be a maleimide, epoxy or (meth) acryloyl group or a combination thereof, and the number of functional groups may be greater than two. Commercially available hybrid resins include bisphenol A epoxy and acrylate hybrid resins such as EA1010, EA1010N (manufactured by Shin-Nakamura Chemical Co., Ltd.), HCT-1, HCT-2 (manufactured by Kagawa Chemical Co., Ltd.). Not limited.

  In one aspect, the hybrid resin has a maleimide group and an epoxy or (meth) acryloyl group in one molecule, as disclosed in PCT / CN2015 / 083963, which is incorporated herein by reference. And preferably has a bisphenol A and DCPD (dicyclopentadiene) phenol-based main chain.

Illustrative compounds include, but are not limited to:

  In the present invention, the molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups in one or more curable resins is greater than 0.2. We have surprisingly found that the selection of the molar equivalent ratio of functional groups of the radiation-curable resin is important for the gel time of the sealant composition, as well as for LC penetration and contamination, adhesion, and sealant reliability. Was found. When the molar equivalent ratio is within this range, the radiation-curable sealant will have an excellent balance of LC penetration, contamination, adhesion, and reliability in the ODF process. If the range is smaller, the overall performance of the sealant in the ODF process will be reduced. Preferably, the molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups is from about 0.25 to about 10, preferably from about 0.3 to about 5.0.

  The amount of the radiation-curable resin may be appropriately selected according to the type of the latent curing agent in the sealing composition. Preferably, the radiation curable resin in the sealing composition is present in an amount of about 30 to about 90%, more preferably about 50 to about 80% by weight, based on the total weight of the components of the sealant composition.

Latent curing agents Latent curing agents are based on latent curing agents that release at a certain temperature. Latent curing agents can be easily obtained from commercially available latent curing agents, and can be used alone or in combination of two or more. Specifically, the latent curing agent preferably used includes an amine compound, a fine powder type modified amine and a modified imidazole compound. Examples of amine-based latent curing agents include dicyandiamide, adipic dihydrazide, oxalic dihydrazide, malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, suberic dihydrazide, azelaic dihydrazide, sehydric acid dihydrazide and dihydrazide such as phthalic acid dihydrazide. Hydrazide. Examples of the modified amine and modified imidazole-based compound include a core-shell type in which the surface of an amine compound (or amine adduct) core is coated with a shell of a modified amine product (surface addition, etc.), and a core-shell type curing agent and epoxy. A masterbatch type curing agent as a mixture with a resin is exemplified.

  Examples of commercially available latent curing agents include, but are not limited to, the following compounds: Adeka Hardener EH-5011S (imidazole type), Adeka Hardener EH-4357S (modified amine type), Adeka Hardener EH-4357PK (Modified amine type), Adeka Hardener EH-4380S (Special hybrid type), Adeka Hardener EH-5001P (Special modified type), Ancamine 2014FG / 2014AS (Modified polyamine), Ancamine 2441 (Modified polyamine), Ancamine 2337s (Modified amine type) ), Fujicure FXR-1081 (modified amine type), Fujicure FXR-1020 (modified amine type), Sunmide LH-210 (modified imidazole type), Sunmide LH-2102 (modified imidazole type), Sunmide LH-2100 (modified imidazole type) Ajicure PN-23 (modified imidazole type), Ajicure PN-23J (modified imidazole type), Ajicure PN-31 (modified imidazole type), Ajicure PN-31J (modified imidazole type), Novacure HX-3722 (master batch type) ), Nov acure HX-3742 (master batch type), Novacuure HX-3613 (master batch type) and mixtures thereof.

  In one preferred embodiment, a latent curing agent having a melting point of about 50 to about 110C, especially about 60 to about 100C, is suitable for use in the radiation-curable sealant composition.

  Preferably, the latent hardener in the sealing composition is present in an amount of about 1 to about 50%, more preferably about 5 to about 40% by weight, based on the total weight of the components of the sealant composition.

Other Ingredients To improve or modify the properties of the sealant composition (eg, flowability, dispensing or printability, storage stability, curing properties and post-curing properties), the sealant composition may include one or more additives. It may further contain an agent, a resin component and the like.

  Components that can be included in the sealant composition as needed include, for example, organic or inorganic fillers, thixotropic agents, silane coupling agents, diluents, modifiers, coloring agents such as pigments and dyes, Examples include, but are not limited to, activators, preservatives, stabilizers, plasticizers, lubricants, defoamers, leveling agents, and the like. In particular, the sealant composition preferably comprises an additive selected from the group consisting of inorganic or organic fillers, thixotropic agents, silane coupling agents, and combinations thereof.

  Suitable fillers that can be optionally used in the present invention include silica, diatomaceous earth, alumina, zinc oxide, iron oxide, magnesium oxide, tin oxide, titanium oxide, magnesium hydroxide, aluminum hydroxide, magnesium carbonate, barium sulfate, Gypsum, calcium silicate, talc, glass beads, sericite activated clay, bentonite, aluminum nitride, inorganic fillers such as silicon nitride; polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polyacrylonitrile, polystyrene, Organic fillers such as, but not limited to, polybutadiene, polypentadiene, polyisoprene, polyisopropylene, and the like. Fillers may be used alone or in combination.

  Suitable thixotropic agents that can optionally be used in the present invention include talc, fumed silica, ultrafine surface-treated calcium carbonate, fine-particle alumina, plate-like alumina; layered compounds such as montmorillonite, and needle-like compounds such as aluminum borate whiskers. Examples include, but are not limited to, compounds. Talc, fumed silica and fine alumina are the preferred thixotropic agents.

  Useful silane coupling agents include vinylmethoxysilane, vinylethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl)- γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane and hexamethyldisilazane. Among them, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, and N- (β-aminoethyl) -γ are used as amino- or epoxy silane coupling agents. -Aminopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β-glycidoxypropylmethyldimethoxysilane are more preferred.

  The radiation-curable sealant composition of the present invention is essentially free of, and preferably free of, a photoinitiator. Examples of photoinitiators include acetophenone-based initiators such as diethoxyacetophenone and benzyldimethyl ketal, benzoin ether-based initiators such as benzoin and benzoin ethyl ether, benzophenone-based initiators such as benzophenone and methyl o-benzoylbenzoate. Agents, butanedione, alpha-diketone-based initiators such as benzyl and acetonaphthophenone, and thio compounds such as methylthioxanthone.

  The radiation-curable sealant composition of the present invention can be obtained, for example, by mixing the above components using a stirrer having a stirring blade and a mixer such as a three-roll mill. The viscosity of the sealant composition is not limited as long as it can be easily dispensed. Preferably, the sealant composition has a viscosity at 25 [deg.] C ranging from about 50 to about 500 Pa.s.

In another aspect, the present invention also relates to a method of manufacturing a liquid crystal display having a liquid crystal layer between a first substrate and a second substrate, the method comprising:
1) a step of applying the radiation-curable sealant composition of the present invention to a sealing region at a peripheral portion of the surface of the first base material;
2) performing radiation curing of the radiation-curable sealant composition to obtain a partially cured product;
3) a step of forming a liquid crystal layer by dropping liquid crystal on a central area surrounded by a sealing area on the surface of the first base material or on a corresponding area of the second base material;
4) laminating the first substrate and the second substrate; and 5) performing a thermal cure of the partially cured product.

  In the present invention, the first substrate and the second substrate are transparent substrates made of glass or plastic. Generally, a transparent electrode, an active matrix element (for example, a TFT), an alignment film, a color filter, and the like are formed on at least one of the opposing surfaces of the two substrates. These configurations can vary depending on the type of LCD. The manufacturing method according to the present invention may be considered to be applied to any type of LCD. Plastic substrates include those made of plastic, for example, polyester, polyarylate, polycarbonate, and poly (ether sulfone).

  In step 1), the sealant composition is applied to the peripheral portion of the surface of the first base material, which is one of the base materials (the surface facing the other base material), so as to make a round around the base material in a frame shape. Apply. As described herein, the portion where the sealant composition is applied to the frame shape is referred to as a seal region. At this time, since the sealant composition is fluid, it can be applied, and can be applied by a known method such as screen printing and dispensing.

  In step 2), the curable resin composition applied to the first substrate is exposed to actinic radiation so that the composition is pre-cured and a partially cured product is obtained. Such a process, preferably with UV light, is intended to make the sealant surface tacky when partially cured but not fully cured for convenience in assembling the two substrates together. This is the so-called "UV B-stage" which means the stage of pre-curing the composition.

  Although other types of actinic radiation may be used, it is preferred to cure the sealant composition by ultraviolet, visible or black light radiation. During curing, the radiation source is preferably substantially perpendicular to the substrate.

  Suitable radiation sources for UV light in the specific wavelength range in step 2) are, for example, UV-A radiation sources [eg UV-H 254 from Panacol-Elosol GmbH, Steinbach, Germany]. Quick-Start UV 1200, UV-F 450, UV-P 250C, UV-P 280/6 or UV-F 900, fluorescent tubes, LED technology or lamps), high or medium pressure mercury lamps ( Here, the mercury vapor may be modified by doping with other elements such as gallium or iron), a pulse lamp (for example known as a UV flash lamp), or a halogen lamp. Further, suitable UV emitters or lamps can also be used in the present invention. The emitter can be placed in a fixed position by moving the illuminated article through a radiation source by a mechanical device, or the emitter can be moved and the illuminated article during the pre-curing of step 2) Need not be changed.

  More preferably, an LED lamp is used in step 2) of the method of the invention, wherein the wavelength of the LED light source is more preferably a single wavelength, generally a narrow spectral output centered on a particular wavelength, +/- -10 nm, preferably in the range of about 365 nm to about 405 nm.

  Generally, the irradiation time is preferably short, for example about 5 minutes or less, preferably about 3 minutes or less, more preferably about 1 minute or less.

  Next, in step 3), liquid crystal is dropped on a central region surrounded by a frame-shaped sealing region on the surface of the first base material or on a corresponding region of the second base material. “Corresponding region” means the region of the second substrate that corresponds to the central region surrounded by the sealing region of the first substrate when the substrate is deposited. Subsequently, the liquid crystal is dropped in a central region, which is preferably surrounded by a sealing region of the first substrate.

  In step 4), the second substrate is superimposed or superimposed on the first substrate and the two substrates are cured under reduced pressure, preferably under vacuum, with a partially cured product therebetween. Can be temporarily fixed. The vacuum can be applied by conventional methods to achieve a vacuum of about 1.0 to about 3.0 Pa. The vacuum generation gap may be from about 0.1 to about 0.5 mm.

  In step 5), the thermal curing is usually performed at a temperature of about 80 to about 150C for about 30 to about 90 minutes.

  Through the above steps, most of the LCD panel is completed.

  The sealant composition used in the present invention may also be used for ODF processes for LCD manufacturing where precise assembly without misalignment is required, especially applications other than the pure thermoset ODF process as described above. obtain.

The radiation-curable sealant composition has a gel time under radiation of 405 nm, about 500 Mw / cm ² of less than about 200 seconds, preferably less than 185 seconds. Gelation of the radiation-curable sealant composition can be performed by inserting or contacting a wooden stick with the sealant composition during radiation curing, pulling up the wooden stick from the sealant composition, and visually confirming the formation of a thread of the sealant composition. You can find out by: At the start of curing, the sealant composition is flowable and no sealant thread forms between the stick end and the sealant. With continued curing and gelling, the flowability of the sealant composition decreases, its viscosity increases, and a thread forms when a wooden stick is inserted into the sealant composition and pulled up. The gel time is defined as the time from the onset of radiation curing that the thread does not adhere to the wooden stick. If the gelation time exceeds 200 seconds, the viscosity of the sealant composition increases during radiation curing, but the risk of liquid crystal penetration even after thermal curing is high.

Examples The following examples are intended to help those skilled in the art to better understand and practice the present invention. The scope of the invention is not limited by the examples, but is defined in the appended claims. All parts and percentages are by weight unless otherwise indicated.

Material curable resin 1: Ebecryl 3708, modified bisphenol A type epoxy diacrylate, curable resin manufactured by Cytec Industries Inc. 2: YL980, bisphenol A type epoxy, curable resin 3: 24-414A, manufactured by Mitsubishi Chemical Corporation, bismaleimide Resin, Henkel Corporation silane coupling agent: Silquest A-187, epoxy-functional silane, Momentive Performance Materials Inc. filler: SO-E2, silica filler, Admatechs Co., Ltd. latent curing agent: EH -4357S, polyamine type latent curing agent, manufactured by ADEKA Corporation

Preparation As Examples (Ex) 1-4, radiation-curable sealant compositions of the present invention having the formulations shown in Table 1 were prepared. All components were sufficiently mixed by a stirrer and then a three-roll mill to obtain a uniform sealant composition. After filtration through a 5 μm mesh, the composition was degassed to remove air bubbles in the composition. Comparative Examples (CE) 1 and 2 were prepared in the same manner except for the presence and the weight ratio of specific components, and the formulations are also shown in Table 1.

Test Method and Result Gelling Time 1 g of each of Examples and Comparative Examples was weighed and put into an LED lamp chamber. The radiation-curable sealant composition was cured by radiation of 405 nm, 500 mW / cm ² . The gel time was measured by inserting or contacting a wooden stick with the sealant composition, pulling up the wooden stick from the sealant composition, and visually checking whether a thread of the sealant composition was formed. The test results are shown in Table 1.

Viscosity The viscosity at 25 ° C. of each example was measured by a rheometer (TA, AR2000 ex) at a shear rate of 1.5 s ⁻¹ , and the thixotropic index (TI) was measured by a viscosity at 1.5 s ⁻¹ / 15 s ⁻¹ . did.

Adhesive Strength The sealant composition of each example was dispensed on L-shaped ITO glass (50 mm × 60 mm) with a line width of 0.5 mm. Each example was placed in an oven for a first cure at a first heating step condition. Opposite ITO glass plates were overlapped, and the two glass plates were fixed. Next, the example was put into an oven at 120 ° C. for 1 hour to completely cure the sealant composition. One glass plate was pulled by an Instron strength tester at a speed of 1.27 mm / sec. The average bond strength of the five test specimens for each example was each recorded.

  In order to test the adhesive strength after aging, five more test pieces were prepared for each example, and a Pressure Cooking Test oven (120 ° C., 100% humidity, 2 atm, ESPEC Corporation, EHS-221M model) was prepared for 24 hours. ). Thereafter, the adhesive strength was tested on an Instron strength tester by recording the average value.

Voltage holding ratio (VHR)
0.03 g of each sealant composition and 0.27 g of liquid crystal were weighed, mixed, and placed in an oven at 120 ° C. for 1 hour. The mixture was removed and kept at room temperature and filled into a specific test cell. VHR was tested on a Toyo 6254 analyzer (Toyo Corporation) at 60 ° C., 5 V and 60 Hz.

NI point change (from nematic phase of liquid crystal to isotropic phase)
0.03 g of each sealant composition and 0.27 g of liquid crystal were weighed, mixed, and placed in an oven at 120 ° C. for 1 hour. The mixture was removed and introduced into a DSC (differential scanning calorimetry) pan and the temperature was increased at 5 ° C / min to 120 ° C. The temperature change between the pure liquid crystal and the liquid crystal mixture containing the sealant composition was recorded.

Water vapor transmission rate (WVTR)
0.5 g of each sealant composition was filled into a specific module and cured at 120 ° C. for 1 hour to obtain a circular specimen having a thickness of 0.3 mm and more than 10 cm ² . Next, the test piece was put into a Mocon PERMATRAN-W (registered trademark) Model 3/61 device (manufactured by Mocon Inc.), and the water vapor permeability was tested at 50 ° C. and 100% RH.

LCD Panel Sealing Performance 1 part by weight of 3.5 μm spacer was added to 100 parts by weight of the sealant composition. After degassing, the sealant composition was dispensed in a rectangular shape on the periphery of the surface of the glass substrate (200 mm × 200 mm) by a Musashi screw dispensing machine. A larger rectangular sealant composition surrounding the perimeter of the rectangle was dispensed as a proximity dummy seal. The diameter of the dispensing nozzle is 0.15 mm, the dispensing speed is 70 mm / sec, and the final line width of the resin composition is 500 μm.

  The substrate on which the sealant was dispensed was put into an LED lamp chamber for UV pre-curing under the curing conditions described in Table 2. The substrate was removed and a few grams of liquid crystal (105% LC amount calculated with respect to the sealing volume) was dropped into the central area surrounded by the sealing area, vacuum degassed and then the second glass base at 3 Kpa. The material was overlaid on the first substrate. After depositing the two glass substrates, the vacuum was released and an LCD cell was obtained, after which the assembly was placed in a 120 ° C. oven to perform a second cure.

  Next, the LCD cell was examined under a microscope. If the penetration width from the liquid crystal to the sealant composition cured in a frame shape was less than 50 μm, the penetration resistance was recorded as “good”. When the permeation width from the liquid crystal to the resin composition cured into a frame was in the range of 50 to 200 μm, the permeation resistance was recorded as “general”. When the penetration width from the liquid crystal to the resin composition cured in a frame shape exceeded 200 μm, the penetration resistance was recorded as “poor”.

  In the LCD performance test, if a color mismatch occurs when a DC voltage of 5 V is applied to the LCD cell, it is assumed that an “uneven” impression has occurred. The unevenness problem usually occurs near the frame of the LCD cell. If there was no apparent color mismatch near the frame, the uneven impression performance was recorded as "Good". If there was a slight color mismatch near the frame, the uneven impression performance was recorded as "General". When there was a serious color mismatch near the frame, the performance of the uneven impression was recorded as “poor”.

  Each of the prepared LCD cells was aged in an oven at 60 ° C. and 90% RH for 3 days. Next, the uneven impression of each LCD cell after aging was tested by applying a DC voltage of 5V to the LCD cell. If there was no apparent color mismatch near the frame, the non-uniform impression resistance was recorded as "good". If there was a slight color mismatch near the frame, the non-uniform impression resistance was recorded as "General". When there was a serious color mismatch near the frame, the non-uniformity impression resistance was recorded as “poor”.

  Table 1 shows the test results.

  As shown in Table 1, the sealant compositions of the present invention have satisfactory properties such as gel time of less than 200 seconds, good adhesion, dispensing properties, LC penetration, LC contamination and uneven impression. Showed excellent resistance to

The mechanism of UV curing is the radical polymerization of the double bond in the bismaleimide resin, so that the content of the bismaleimide resin and its ratio to other resins in the composition will result in good resistance to LC penetration and LC contamination. Important to achieve. In Comparative Examples 1 and 2, since the molar ratio of the maleimide group to the other functional resin (epoxy or acrylate) was less than 0.2, each gel time under irradiation of 500 mW / cm ² by a 405 nm LED lamp was 200. Longer than a second, showed poor resistance to LC penetration and uneven impression. This is mainly due to the slower UV cure rate of the sealant. Due to the slow UV cure rate, LC penetration cannot be prevented and the compounds with small molecules in the sealant composition penetrate the liquid crystal during heat curing, eventually causing an uneven impression.

  From the above results, since the sealant composition of the present invention has a good balance of barrier properties, adhesive strength, LC penetration / contamination resistance, and uneven impression resistance, it can be used in the two-stage thermosetting ODF method. It was clearly shown to be suitable for

Claims (13)

  A radiation-curable sealant composition comprising one or more curable resins having a group selected from an epoxy group, a (meth) acryloyl group, a maleimide group, and combinations thereof, and a latent curing agent, A radiation curable sealant composition, wherein the molar equivalent ratio of maleimide groups to (meth) acryloyl groups and / or epoxy groups in one or more curable resins is greater than 0.2.   The one or more curable resins are selected from epoxy resins, (meth) acrylate resins, maleimide resins, hybrid resins having at least two groups selected from epoxy groups, (meth) acryloyl groups and maleimide groups, and mixtures thereof. The radiation-curable sealant composition according to claim 1, which is selected.   The radiation-curable sealant composition according to claim 2, wherein the epoxy resin is selected from a bisphenol A epoxy resin, a bisphenol F epoxy resin, and a bisphenol S epoxy resin.   Radiation curable sealant composition according to claim 2, wherein the (meth) acrylate resin is an epoxy (meth) acrylate, preferably a fully (meth) acrylated epoxy. The maleimide resin comprises one or more, preferably one or two, moieties (I):
[Wherein R ¹ and R ² are H or a C _1-6 alkyl group, or R ¹ and R ² together become a C _2-6 alkylene group]
The radiation-curable sealant composition according to claim 2, which has a partial structure represented by the following formula:   The molar equivalent ratio of the maleimide group to the (meth) acryloyl group and / or the epoxy group in one or more curable resins is 0.25 to 10, preferably 0.3 to 5.0. The radiation-curable sealant composition according to claim 1.   The one or more curable resins in the sealing composition are present in an amount of 30 to 90% by weight, more preferably 50 to 80% by weight, based on the total weight of the components of the sealant composition. 7. The radiation-curable sealant composition according to any one of 6.   Radiation-curable sealant composition according to any of the preceding claims, wherein the latent curing agent has a melting point between 50 and 110C, in particular between 60 and 100C.   Radiation curing according to any of the preceding claims, wherein the latent curing agent is present in an amount of 1 to 50% by weight, more preferably 5 to 40% by weight, based on the total weight of the components of the sealant composition. Sealant composition.   Radiation-curable sealant composition according to any of the preceding claims, wherein the radiation-curable sealant composition is essentially free of photoinitiators, preferably free of photoinitiators. Radiation curable sealant composition is less than 200 seconds, preferably less than 185 seconds, 405 nm has a gel time of a radiation of 500 MW / cm ^2, the radiation curable sealant according to any one of claims 1 to 10 Composition. 1) a step of applying the radiation-curable sealant composition according to any one of claims 1 to 11 to a sealing region at a peripheral portion of a surface of the first base material;
2) performing radiation curing of the radiation-curable sealant composition to obtain a partially cured product;
3) a step of forming a liquid crystal layer by dropping liquid crystal on a central area surrounded by a sealing area on the surface of the first base material or on a corresponding area of the second base material;
4) laminating the first and second substrates; and 5) performing a thermal cure of the partially cured product, between the first and second substrates. A method for manufacturing a liquid crystal display having a liquid crystal layer.   Use of the radiation-curable sealant composition according to any one of claims 1 to 11 or the method for producing a liquid crystal display according to claim 12, in a one-drop fill method for producing a liquid crystal device.