TWI879899B - Sealant for liquid crystal dripping method and method for manufacturing liquid crystal display panel - Google Patents

Abstract

The subject of the present invention is to provide a sealing agent for a liquid crystal dripping method and a method for manufacturing a liquid crystal display panel, wherein the sealing agent for a liquid crystal dripping method can form a sealing member with high bonding strength with a substrate that can also cope with the narrow frame of a liquid crystal display panel and is not easily dissolved in liquid crystal. The sealing agent for a liquid crystal dripping method that solves the problem includes an epoxy compound having no polymerizable functional group other than an epoxy group, a (meth) acrylic group-epoxy group-containing compound having both a (meth) acrylic group and an epoxy group in one molecule, a (meth) acrylic compound having no epoxy group, a thermosetting agent, and a photopolymerization initiator, and the content of the epoxy compound is 22 mass % to 38 mass %. A mixture of the sealant for the liquid crystal dropping method and liquid crystal in a mass ratio of 1:10 was heated at 120°C for 1 hour, a voltage of 5 V was applied for 1 second and short-circuited for 0.1 second, and then measured 30 seconds later. The residual DC value was less than 200% of the residual DC value measured using only the liquid crystal.

Description

Sealant for liquid crystal dripping method and method for manufacturing liquid crystal display panel

The present invention relates to a sealing agent for liquid crystal dripping method and a method for manufacturing a liquid crystal display panel.

When a liquid crystal display panel is manufactured by a liquid crystal dripping method, a liquid crystal sealant is applied to form a sealing pattern. Then, liquid crystal is dripped onto a substrate or a substrate paired therewith on which the sealing pattern is formed, and the substrates are bonded together under vacuum. Then, the sealing pattern is cured by ultraviolet (UV) irradiation or heating to form a sealing member. However, in this method, since liquid crystal is dripped when the liquid crystal sealant is not cured, there is a possibility that impurities or low molecular components in the liquid crystal sealant are dissolved into the liquid crystal. Moreover, if low molecular components are dissolved into the liquid crystal, poor display called afterimages is likely to occur in the liquid crystal display panel.

Here, most of the previous liquid crystal sealants contain UV-curable (meth) acrylic compounds and thermosetting epoxy compounds. Moreover, epoxy compounds are generally not cured by UV curing. Therefore, a large amount of low molecular weight epoxy compounds are still contained in the sealing pattern after UV curing. Moreover, when the sealing pattern is heated to thermally cure the sealing pattern, the liquid crystal undergoes a phase transition due to the heat, and the epoxy compounds in the sealing pattern are easily dissolved into the liquid crystal.

Therefore, it has been proposed that: by using a compound having a (meth)acrylic group and an epoxy group in one molecule, UV curability and heat curability are ensured, and the dissolution of epoxy compounds into liquid crystals is suppressed (for example, Patent Document 1). In addition, it has also been proposed that: by using a crystalline epoxy compound having a melting point of 50°C or more, the dissolution of epoxy compounds into liquid crystals is suppressed (Patent Document 2). [Prior Art Document] [Patent Document]

[Patent document 1] Japanese Patent Publication No. 2015-28184 [Patent document 2] Japanese Patent Publication No. 2006-23583

[Problems to be solved by the invention] In recent years, it has been required to increase the liquid crystal display area of a liquid crystal display panel and to narrow the width of the area surrounding the liquid crystal display area (hereinafter also referred to as "narrowing the frame"). In order to achieve narrowing the frame, it is also indispensable to narrow the width of the sealing member. Among them, in the previous sealing member, if the width is narrowed, the strength is likely to become insufficient, and peeling occurs at the interface between the substrate and the sealing member, which is likely to cause liquid crystal leakage.

In addition, the epoxy group contained in the epoxy compound etc. greatly contributes to the bonding strength between the sealing member and the substrate. In the technology described in the patent document 1, the compound having the epoxy group is polymerized by UV curing. Therefore, during thermal curing, the epoxy group is difficult to move freely, and the epoxy group cannot fully contribute to the bonding with the substrate. On the other hand, in the technology described in the patent document 2, since the viscosity of the liquid crystal sealant will increase, it is difficult to include a large amount of epoxy compounds with a high melting point in the liquid crystal sealant. Therefore, even with this technology, it is difficult to obtain sufficient bonding strength.

The present invention is made in view of the above-mentioned problem. Specifically, the purpose is to provide a sealing agent for liquid crystal dripping method and a method for manufacturing a liquid crystal display panel, wherein the sealing agent for liquid crystal dripping method can form a sealing component with high bonding strength with the substrate that can also cope with the narrow frame of the liquid crystal display panel and is not easily dissolved in the liquid crystal. [Means for solving the problem]

The present invention provides the following sealing agent for liquid crystal dripping method. [1] A sealing agent for liquid crystal dripping method, comprising an epoxy compound having no polymerizable functional group other than an epoxy group, a (meth)acrylic-epoxy-containing compound having both a (meth)acrylic group and an epoxy group in one molecule, a (meth)acrylic compound having no epoxy group, a thermosetting agent and a photopolymerization initiator, wherein the content of the epoxy compound is 22 mass % to 38 mass %, and a mixture of the sealing agent for liquid crystal dripping method and liquid crystal in a mass ratio of 1:10 is heated at 120°C for 1 hour and a voltage of 5 V is applied for 1 second and short-circuited for 0.1 second, and then measured after 30 seconds. The residual direct current (DC) value obtained is lower than that obtained when the liquid crystal is heated at 120°C for 1 hour and a voltage of 5 V is applied for 1 second and short-circuited for 0.1 second. The residual DC value measured after applying voltage V for 1 second and short-circuiting for 0.1 second and then measuring after 30 seconds was less than 200%.

[2] The sealing agent for liquid crystal dropping method as described in [1], wherein, with respect to each component contained in the sealing agent for liquid crystal dropping method, when each component is mixed with liquid crystal at a mass ratio of 1:10, heated at 120°C for 1 hour, a voltage of 5 V is applied for 1 second and a short circuit is performed for 0.1 second, and then the residual DC value is measured after 30 seconds, the residual DC value of 98% by mass or more of the components in the sealing agent for liquid crystal dropping method is 300% or less relative to the residual DC value obtained by heating the liquid crystal at 120°C for 1 hour, applying a voltage of 5 V for 1 second and a short circuit is performed for 0.1 second, and then the residual DC value is measured after 30 seconds. [3] The sealing agent for liquid crystal dropping method according to [1] or [2], wherein the proportion of the component having a molecular weight of 500 or more in the epoxy compound is 25% by mass or more.

[4] The sealing agent for liquid crystal dropping method as described in any one of [1] to [3], wherein the thermosetting agent is one or more selected from the group consisting of organic acid dihydrazide-based thermolatent curing agents, imidazole-based thermolatent curing agents, amine adduct-based thermolatent curing agents, and polyamine-based thermolatent curing agents. [5] The sealing agent for liquid crystal dropping method as described in any one of [1] to [4], further comprising inorganic particles. [6] The sealing agent for liquid crystal dropping method as described in any one of [1] to [5], further comprising organic particles. [7] The sealing agent for liquid crystal dropping method as described in any one of [1] to [6], further comprising a silane coupling agent.

[8] A method for manufacturing a liquid crystal display panel, comprising: a step of coating a sealant for a liquid crystal dripping method as described in any one of [1] to [7] on one of a pair of substrates to form a sealing pattern; a step of dripping liquid crystal into the area of the sealing pattern of one of the substrates or on the other substrate when the sealing pattern is not hardened; a step of overlapping the one substrate and the other substrate with the sealing pattern interposed therebetween; and a step of hardening the sealing pattern.

[9] The method for manufacturing a liquid crystal display panel as described in [8], wherein, in the step of hardening the sealing pattern, the sealing pattern is irradiated with light. [10] The method for manufacturing a liquid crystal display panel as described in [9], wherein, in the step of hardening the sealing pattern, heating is performed after irradiating with light. [Effect of the Invention]

The sealing agent for the liquid crystal dropping method of the present invention is not easily dissolved in the liquid crystal. Furthermore, the sealing member obtained by the sealing agent for the liquid crystal dropping method has high bonding strength with the substrate. Therefore, in the obtained liquid crystal display panel, liquid crystal leakage or afterimage is not easily generated, and narrow frame can also be achieved.

1. Sealant for liquid crystal dripping method The sealant for liquid crystal dripping method of the present invention (hereinafter, also referred to as "sealant") is a sealing member for manufacturing a liquid crystal display panel, and can be preferably used in the case of manufacturing a liquid crystal display panel by a liquid crystal dripping method. Among them, it can also be used to manufacture a liquid crystal display panel by a liquid crystal injection method, etc.

As mentioned above, if a large amount of epoxy compounds that can help improve the bonding strength are contained in the conventional sealant, there is a problem that the liquid crystal is easily contaminated when manufacturing the liquid crystal display panel. On the other hand, if the amount of epoxy compounds is reduced, for example, when the frame of the liquid crystal display panel is narrowed, sufficient bonding strength cannot be obtained, and peeling occurs between the substrate and the cured product of the sealant (sealing member).

In contrast, the inventors have found through diligent research that by adjusting the composition of the sealant so that the amount of the epoxy compound is 22 mass % to 38 mass % relative to the total amount of the sealant, and by making the residual DC value of the mixture of the sealant and liquid crystal in a specified ratio less than 200% relative to the residual DC value of the liquid crystal alone, the bonding strength between the obtained sealing member and the substrate is greatly improved, and on the other hand, it is less likely to produce residual images caused by the dissolution of components in the sealant.

Here, the residual DC value of a mixture containing a sealant and a liquid crystal can be measured as follows. First, a sealant and a liquid crystal (e.g., MLC-7026, manufactured by Merck) are put into a glass bottle at a mass ratio of 1:10 and mixed. Then, heat at 120°C for 1 hour. Then, take out the mixture and inject it into a glass cell (e.g., KSSZ-10/B111M1NSS05, manufactured by EHC) on which an alignment film and a transparent electrode are pre-formed. Then, a voltage of 5 V is applied to the obtained cell for 1 second and short-circuited for 0.1 second. Then, the voltage (residual DC value) remaining after 30 seconds is measured using a 6254 type measuring device (manufactured by Toyo Technica).

On the other hand, in the case of measuring the residual DC value of only the liquid crystal, only the liquid crystal is put into a glass bottle and mixed. Then, it is heated at 120°C for 1 hour. Then, the liquid crystal is taken out and injected into a glass unit (for example, KSSZ-10/B111M1NSS05, manufactured by EHC) on which an alignment film and a transparent electrode are pre-formed. A voltage of 5 V is applied to the obtained unit for 1 second and short-circuited for 0.1 second. Then, the voltage (residual DC value) remaining after 30 seconds is measured using, for example, a 6254 type measuring device (manufactured by Toyo Technica).

Here, the residual DC value of the mixture containing the sealant and the liquid crystal varies slightly depending on the type of liquid crystal, but it is sufficient as long as it is less than 200% relative to the residual DC value of the liquid crystal alone, and preferably less than 180%. The residual DC value of the mixture can be adjusted according to the type of components constituting the sealant. For example, many components contained in the sealant are adjusted so that the individual residual DC value is less than 300% relative to the residual DC value of the liquid crystal alone, thereby satisfying the residual DC value of the mixture. More specifically, it is preferred that the proportion of the components whose individual residual DC value is less than 300% relative to the residual DC value of the liquid crystal alone is 98% by mass or more relative to the total amount of the sealant.

The individual residual DC values of each component in the sealant can be measured as follows. First, each component and liquid crystal (e.g., MLC-7026, manufactured by Merck) are put into a glass bottle at a mass ratio of 1:10 and mixed. The mixture is heated at 120°C for 1 hour. Then, the mixture is injected into a glass cell (e.g., KSSZ-10/B111M1NSS05, manufactured by EHC) on which an alignment film and a transparent electrode are pre-formed. A voltage of 5 V is applied to the obtained cell for 1 second and short-circuited for 0.1 second. Then, the voltage (residual DC value) remaining after 30 seconds is measured using, for example, a 6254 type measuring device (manufactured by Toyo Technica). Furthermore, it is more preferred that the residual DC value of each component is 280% or less with respect to the residual DC value of the liquid crystal as a reference.

Here, the sealant of the present invention includes an epoxy compound, a compound containing a (meth) acrylic group-epoxy group, a (meth) acrylic compound, a thermosetting agent, and a photopolymerization initiator. In addition to these components, inorganic particles or organic particles, silane coupling agents, etc. may also be included as needed. Furthermore, the description of (meth) acrylic acid in this specification includes acrylic acid or methacrylic acid or both. Below, the components and physical properties of the sealant of the present invention are described in detail.

(1) Epoxy compounds Epoxy compounds are compounds that contain at least an epoxy group in one molecule and do not have any polymerizable functional groups other than the epoxy group. The so-called polymerizable functional group in this specification refers to a functional group that is activated and undergoes a polymerization reaction by light irradiation or heating, a heat curing agent or a photopolymerization initiator, a catalyst, etc. The polymerizable functional group includes a photopolymerizable functional group, a heat polymerizable functional group, an addition polymerizable functional group, etc. Specific examples include (meth)acrylic acid group, vinyl group, acrylamide group, epoxy group, isocyanate group, silanol group, etc.

The number of epoxy groups contained in one molecule of the epoxy compound is preferably two or more. If the number of epoxy groups in the epoxy compound is two or more, the adhesion between the obtained sealing member and the substrate of the liquid crystal display panel becomes good. Furthermore, the moisture resistance of the obtained sealing member is also easily improved.

The epoxy compound may be in liquid or solid form at room temperature. From the viewpoint of the viscosity of the obtained sealant, the softening point of the epoxy compound is preferably 40°C to 110°C.

Here, the epoxy compound may be a monomer, an oligomer, or a polymer. The molecular weight (or weight average molecular weight) of the epoxy compound is generally preferably 220 to 3000, more preferably 250 to 2500, and further preferably 300 to 2000. Among them, relative to the total amount of the epoxy compound, the proportion of components with a molecular weight of 500 or more is preferably 25% by mass or more. Epoxy compounds with a molecular weight of 500 or more are not easily soluble in liquid crystals. Therefore, in such epoxy compounds, the individual residual DC value is easily less than 300% compared to the residual DC value of only liquid crystals. The weight average molecular weight of the epoxy compound can be measured, for example, by gel permeation chromatography (GPC) (polystyrene conversion). The epoxy compound may also include a portion of the epoxy compound having a residual DC value exceeding 300% of the residual DC value of the liquid crystal alone.

Here, the structure of the epoxy compound is not particularly limited, and examples thereof include aromatic epoxy compounds containing an aromatic ring in the main chain. Examples of aromatic epoxy compounds include aromatic polyglycidyl ether compounds obtained by reacting aromatic diols represented by bisphenol A, bisphenol S, bisphenol F, bisphenol AD, etc., or diols obtained by modifying these diols with ethylene glycol, propylene glycol, or alkanediol, with epichlorohydrin; novolac-type polyglycidyl ether compounds obtained by reacting novolac resins derived from phenol or cresol and formaldehyde, or polyphenols represented by polyalkenylphenol or copolymers thereof, with epichlorohydrin; glycidyl ether compounds of xylylphenol resins; naphthalene-type epoxy compounds; diphenyl ether-type epoxy compounds; biphenyl-type epoxy compounds, etc.

More specifically, the aromatic epoxy compound is preferably a cresol novolac type epoxy compound, a phenol novolac type epoxy compound, a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a trisphenol methane type epoxy compound, a trisphenol ethane type epoxy compound, a trisphenol type epoxy compound, a diphenyl ether type epoxy compound, or a biphenyl type epoxy compound.

The sealant may contain only one epoxy compound or two or more epoxy compounds. When the residual DC value of each epoxy compound is measured as described above, the value is preferably 150 mV or less.

In addition, the content of the epoxy compound is preferably 22 mass % to 38 mass %, more preferably 22 mass % to 36 mass %, and further preferably 23 mass % to 35 mass % relative to the total amount of the sealant. If the amount of the epoxy compound is 25 mass % or more, the bonding strength between the sealing member obtained by the sealant and the substrate of the liquid crystal display panel is improved, and the narrow frame of the liquid crystal display panel can also be coped with. On the other hand, if the amount of the epoxy compound is 38 mass % or less, the residual DC value of the mixture of the sealant and the liquid crystal measured as described above is easily less than 200% relative to the residual DC value of the liquid crystal alone, and it is not easy to produce residual images in the obtained liquid crystal display panel.

(2) (Meth)acrylic acid-epoxy group-containing compounds The (meth)acrylic acid-epoxy group-containing compound may be a compound having an epoxy group and a (meth)acrylic acid group in one molecule.

If the sealant contains only the epoxy compound and the (meth)acrylic compound described later, the compatibility of these compounds may be low. In contrast, if the sealant further contains a (meth)acrylic-epoxy-containing compound, the compatibility of the epoxy compound and the (meth)acrylic compound is improved, and the epoxy compound is less likely to be eluted into the liquid crystal.

Here, the number of epoxy groups and (meth)acrylic groups in one molecule of the (meth)acrylic-epoxy-containing compound is not particularly limited, and may be, for example, one each. In addition, the number of epoxy groups and the number of (meth)acrylic groups may be the same or different. Examples of the (meth)acrylic-epoxy-containing compound include (meth)acrylic-modified epoxy compounds obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of an alkaline catalyst.

The epoxy compound used in the preparation of the (meth)acrylic acid-modified epoxy compound may be any epoxy compound having two or more epoxy groups in the molecule, including bisphenol-type epoxy compounds such as bisphenol A type, bisphenol F type, 2,2'-diallylbisphenol A type, bisphenol AD type, and hydrogenated bisphenol type; novolac-type epoxy compounds such as phenol novolac type, cresol novolac type, biphenyl novolac type, and trisphenol novolac type; biphenyl-type epoxy compounds; naphthalene-type epoxy compounds, and the like.

Among them, the (meth)acrylic acid-modified epoxy compound obtained by (meth)acrylic acid modification of a trifunctional or tetrafunctional or other multifunctional epoxy compound has a high crosslinking density. Therefore, if the sealant contains such a (meth)acrylic acid-modified epoxy compound, the bonding strength between the sealing member and the substrate is easily reduced when manufacturing a liquid crystal display panel. Therefore, the (meth)acrylic acid-modified epoxy compound obtained by (meth)acrylic acid modification of a difunctional epoxy compound is preferred.

The epoxy compound used in the preparation of the (meth)acrylic acid modified epoxy compound is preferably a biphenyl type epoxy compound, a naphthalene type epoxy compound, and a bisphenol type epoxy compound. From the viewpoint of the coating efficiency of the sealant, a bisphenol type epoxy resin such as bisphenol A type and bisphenol F type is further preferred. Furthermore, the epoxy compound used in the preparation of the (meth)acrylic acid modified epoxy compound may be one type or two or more types. In addition, the epoxy compound used in the preparation of the (meth)acrylic acid modified epoxy compound is preferably highly purified by molecular distillation, washing, or the like.

In addition, the reaction of the epoxy compound and (meth)acrylic acid can be carried out according to conventional methods. When the reaction is carried out, (meth)acrylic acid reacts with a part of the epoxy groups in the epoxy compound to obtain a (meth)acrylic acid-modified epoxy compound having a (meth)acrylic acid group and an epoxy group. Among them, there is the following situation: the reaction product contains not only the (meth)acrylic acid-modified epoxy compound, but also unreacted epoxy compounds or (meth)acrylic acid and (meth)acrylic acid. The (meth)acrylic acid-modified epoxy compound can also be isolated from the product and used for a sealant, but the unreacted epoxy compound is equivalent to the epoxy compound having no polymerizable functional group other than the epoxy group. In addition, the (meth)acrylic acid compound formed by the reaction of (meth)acrylic acid with all the epoxy groups of the epoxy compound is equivalent to the (meth)acrylic acid compound described below. Therefore, the reaction product can be used as a sealant.

Here, the molecular weight (weight average molecular weight) of the (meth)acrylic-epoxy-containing compound is preferably 310 to 1000, more preferably 350 to 900. The weight average molecular weight Mw of the (meth)acrylic-epoxy-containing compound can be measured by gel permeation chromatography (GPC), for example (polystyrene conversion). When the molecular weight of the (meth)acrylic-epoxy-containing compound is within this range, the viscosity of the sealant is likely to be within a desired range.

The amount of the (meth)acrylic-epoxy-containing compound contained in the sealant is preferably 15% to 50% by mass, more preferably 18% to 40% by mass, and further preferably 20% to 35% by mass relative to the total amount of the sealant. If the amount of the (meth)acrylic-epoxy-containing compound is 15% by mass or more, the bonding strength between the sealing member obtained by the sealant and the substrate of the liquid crystal display panel is improved, and the narrow frame of the liquid crystal display panel can also be coped with. On the other hand, if the amount of the (meth)acrylic-epoxy-containing compound is 50% by mass or less, the residual DC value of the mixture of the sealant and the liquid crystal is likely to be less than 200% relative to the residual DC value of the liquid crystal alone, and it is not easy to produce residual images in the obtained liquid crystal display panel.

(3) (Meth)acrylic acid compound A (meth)acrylic acid compound is a compound containing one or more (meth)acrylic acid groups in one molecule and having no epoxy group. A (meth)acrylic acid compound may be a monomer, an oligomer, or a polymer.

The number of (meth)acrylic groups contained in one molecule of the (meth)acrylic compound is preferably two or more. When the number of (meth)acrylic groups in the (meth)acrylic compound is two or more, the photocurability of the sealant becomes good.

Here, examples of the (meth)acrylic compound include di(meth)acrylates of polyethylene glycol, propylene glycol, polypropylene glycol, etc.; di(meth)acrylate of tri(2-hydroxyethyl)isocyanurate; di(meth)acrylate of a diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol; di(meth)acrylate of a diol obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A; di(meth)acrylate of a diol obtained by adding 3 or more mol of ethylene oxide or propylene oxide to 1 mol of trihydroxymethylpropane; di(meth)acrylate of a diol obtained by adding 4 or more mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A; tri(meth)acrylate of tri(2-hydroxyethyl)isocyanurate Ester; tri(meth)acrylate of trihydroxymethylpropane or its oligomer; tri(meth)acrylate of pentaerythritol or its oligomer; poly(meth)acrylate of dipentaerythritol; tri(acryloxyethyl) isocyanurate; caprolactone-modified tri(acryloxyethyl) isocyanurate; caprolactone-modified tri(methacryloxyethyl) isocyanurate; alkyl-modified poly(meth)acrylate of dipentaerythritol Ester; poly(meth)acrylate of dipentaerythritol modified with caprolactone; di(meth)acrylate of neopentyl glycol hydroxytrimethylacetate; di(meth)acrylate of neopentyl glycol hydroxytrimethylacetate modified with caprolactone; (meth)acrylate of ethylene oxide modified phosphoric acid; (meth)acrylate of ethylene oxide modified alkylated phosphoric acid; oligo(meth)acrylate of neopentyl glycol, trihydroxymethylpropane and pentaerythritol. In addition, compounds obtained by reacting all of the above-mentioned epoxy compounds containing epoxy groups with (meth)acrylic acid may also be included.

Among these, the glass transition temperature of the (meth)acrylic compound is preferably 25° C. or higher and less than 200° C. from the viewpoint of easily bringing the elastic modulus of the film after photocuring of the sealant into the desired range. The glass transition temperature is more preferably 40° C. to 200° C., and further preferably 50° C. to 150° C. The glass transition temperature can be measured by a viscoelasticity measuring device (DMS).

The molecular weight (or weight average molecular weight) of the (meth)acrylic compound is preferably 310 to 1000, more preferably 400 to 900. The weight average molecular weight Mw of the (meth)acrylic compound can be measured by gel permeation chromatography (GPC), for example (polystyrene conversion). When the molecular weight of the (meth)acrylic compound is within this range, the viscosity of the sealant is likely to be within the desired range.

The amount of the (meth)acrylic compound contained in the sealant also depends on the desired curability of the sealant, but is preferably 15% to 40% by mass, more preferably 18% to 35% by mass, and further preferably 20% to 32% by mass relative to the total amount of the sealant. If the amount of the (meth)acrylic compound is within the above range, the elastic modulus of the sealant after light curing tends to be good.

(4) Thermosetting agent Thermosetting agent may be any component that can cure the epoxy compound by heating. Thermosetting agent is preferably a compound that does not cure the epoxy compound or (meth)acrylic-epoxy-containing compound under normal storage conditions (room temperature, visible light, etc.), but cures these compounds by heating. A sealant containing such a thermosetting agent can achieve both storage stability and thermosetting properties. In addition, as a thermosetting agent, a compound that can cure an epoxy compound (hereinafter also referred to as "epoxy curing agent") is preferred.

From the viewpoint of improving the viscosity stability of the sealant without impairing the moisture resistance of the obtained sealing member, the melting point of the epoxy curing agent is preferably 50°C or more and 250°C or less, more preferably 100°C or more and 200°C or less, and further preferably 150°C or more and 200°C or less. If the melting point of the epoxy curing agent is within this range, the sealant can be one-liquid curing. If the sealant is one-liquid curing, it is not necessary to mix the main agent and the curing agent when using it, so the workability is excellent.

Examples of epoxy curing agents include organic acid dihydrazide-based thermal latent curing agents, imidazole-based thermal latent curing agents, amine adduct-based thermal latent curing agents, and polyamine-based thermal latent curing agents.

Examples of epoxy curing agents include organic acid dihydrazide-based thermal latent curing agents, imidazole-based thermal latent curing agents, dicyandiamide-based thermal latent curing agents, amine adduct-based thermal latent curing agents, and polyamine-based thermal latent curing agents.

Examples of organic acid dihydrazide-based thermal latent curing agents include adipic acid dihydrazide (melting point 181°C), 1,3-bis(hydrazinocarbonylethyl)-5-isopropylhydantoin (melting point 120°C), 7,11-octadecadiene-1,18-dicarbonylhydrazide (melting point 160°C), dodecanedioic acid dihydrazide (melting point 190°C), and sebacic acid dihydrazide (melting point 189°C).

Examples of imidazole-based heat latent curing agents include 2,4-diamino-6-[2'-ethylimidazolyl-(1')]-ethyltriazine (melting point: 215°C to 225°C) and 2-phenylimidazole (melting point: 137°C to 147°C).

Examples of the dicyandiamide-based heat latent curing agent include dicyandiamide (melting point: 209° C.) and the like.

The amine addition-based thermal latent curing agent is a thermal latent curing agent comprising an addition compound obtained by reacting an amine compound having catalytic activity with an arbitrary compound. Examples of amine addition-based thermal latent hardeners include Amicure PN-40 (melting point 110°C) manufactured by Ajinomoto Fine-Techno, Amicure PN-23 (melting point 100°C) manufactured by Ajinomoto Fine-Techno, Amicure PN-31 (melting point 115°C) manufactured by Ajinomoto Fine-Techno, Amicure PN-H (melting point 115°C) manufactured by Ajinomoto Fine-Techno, Amicure MY-24 (melting point 120°C) manufactured by Ajinomoto Fine-Techno, and Amicure MY-H (melting point 131°C) manufactured by Ajinomoto Fine-Techno.

Polyamine-based heat latent hardeners are heat latent hardeners having a polymer structure obtained by reacting amines with epoxides, and examples thereof include Adeka Hardener EH4339S (softening point 120°C to 130°C) manufactured by Adeka Corporation and Adeka Hardener EH4357S (softening point 73°C to 83°C) manufactured by Adeka Corporation.

Among the above, organic acid dihydrazide-based heat latent curing agents, imidazole-based heat latent curing agents, amine adduct-based heat latent curing agents, or polyamine-based heat latent curing agents are preferred from the viewpoints of availability, compatibility with other components, etc. The sealant may contain only one epoxy curing agent, or may contain two or more.

The content of the thermosetting agent is preferably 1 mass % to 20 mass %, more preferably 2 mass % to 18 mass %, and further preferably 3 mass % to 15 mass % relative to the total amount of the sealant. When the amount of the thermosetting agent is within this range, the thermosetting property of the sealant becomes good.

(5) Photopolymerization initiator The photopolymerization initiator may be any compound that can generate active species by irradiation with light, and may be a self-cleaving type photopolymerization initiator or a dehydrogenating type photopolymerization initiator. The sealant may contain only one type of photopolymerization initiator or may contain two or more types.

Examples of the self-cleaving photopolymerization initiator include alkyl phenone compounds (e.g., benzyl dimethyl ketal such as 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE 651 manufactured by BASF), α-aminoalkyl phenone such as 2-methyl-2-oxo-(4-thiomethylphenyl)propane-1-one (IRGACURE 907 manufactured by BASF), 1-hydroxy-cyclohexyl-phenyl- ketones (such as α-hydroxy alkyl phenyl ketones, such as IRGACURE 184 manufactured by BASF), acyl phosphine oxide compounds (such as 2,4,6-trimethylbenzoin diphenylphosphine oxide), titaniumocene compounds (such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium), acetophenone compounds (such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1 -ketone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholinyl (4-thiomethylphenyl) propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone, etc.), benzoyl carboxylate compounds (such as methyl benzoyl carboxylate, etc.), benzoin ether compounds (such as benzoin , benzoin methyl ether, benzoin isopropyl ether, etc.) and oxime ester compounds (for example, 1,2-octanedione-1-[4-(phenylthio)-2-(O-benzoyl oxime)] (IRGACURE OXE01 manufactured by BASF), ethyl ketone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyl oxime) (IRGACURE OXE02 manufactured by BASF), etc.).

Examples of dehydrogenation-type photopolymerization initiators include benzophenone compounds (e.g., benzophenone, methyl o-benzoylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetrakis(tert-butylcarbonylperoxide)benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, etc.), thioxanthrone compounds (e.g., thioxanthrone, 2-chlorothioxanthrone (manufactured by Tokyo Chemical Industry Co., Ltd.), 1-chloro-4-propoxythioxanthrone, 1-chloro-4-ethoxythioxanthrone (manufactured by Lambson Co., Ltd.), Limited), 2-isopropylthioxanthrone (Speedcure ITX manufactured by Lambson Limited), 4-isopropylthioxanthrone, 2,4-dimethylthioxanthrone, 2,4-diethylthioxanthrone (Speedcure DETX manufactured by Lambson Limited), 2,4-dichlorothioxanthrone), anthraquinone compounds (such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, etc.), 2-hydroxyanthraquinone (2-Hydroxyanthraquinone manufactured by Tokyo Chemical Industry Co., Ltd.), 2,6-dihydroxyanthraquinone (Anthraflavic manufactured by Tokyo Chemical Industry Co., Ltd.), Acid), 2-hydroxymethylanthraquinone (2-(Hydroxymethyl)anthraquinone manufactured by Junsei Chemical Co., Ltd.), and benzoyl compounds.

The absorption wavelength of the photopolymerization initiator is not particularly limited, and for example, a photopolymerization initiator that absorbs light with a wavelength of 360 nm or more is preferred. Among them, a photopolymerization initiator that absorbs light in the visible light region is more preferred, and a photopolymerization initiator that absorbs light with a wavelength of 360 nm to 780 nm is further preferred, and a photopolymerization initiator that absorbs light with a wavelength of 360 nm to 430 nm is particularly preferred.

Examples of the photopolymerization initiator that absorbs light having a wavelength of 360 nm or more include alkyl phenoxide compounds, acyl phosphine oxide compounds, titanocene compounds, oxime ester compounds, thioxanthrone compounds, and anthraquinone compounds, with oxime ester compounds being preferred.

Furthermore, the structure of the photopolymerization initiator can be identified by combining high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS) with nuclear magnetic resonance (NMR) or infrared (IR) analysis.

The molecular weight of the photopolymerization initiator is preferably, for example, 200 or more and 5000 or less. If the molecular weight is 200 or more, the photopolymerization initiator is not easily eluted into the liquid crystal when the sealant contacts the liquid crystal. On the other hand, if the molecular weight is 5000 or less, the compatibility with the (meth) acrylic acid compound and the like is improved, and the curability of the sealant is easily improved. The molecular weight of the photopolymerization initiator is more preferably 230 or more and 3000 or less, and further preferably 230 or more and 1500 or less.

The molecular weight of the photopolymerization initiator can be determined as the "relative molecular mass" of the molecular structure of the main peak detected during analysis using high performance liquid chromatography (HPLC).

Specifically, a sample solution is prepared by dissolving a photopolymerization initiator in tetrahydrofuran (THF), and then subjected to high performance liquid chromatography (HPLC) measurement. Then, the area percentage of the detected peak (the ratio of the area of each peak to the total area of all peaks) is calculated to confirm the presence or absence of a main peak. The so-called main peak refers to the peak with the highest intensity (the peak with the highest peak height) among all peaks detected at a characteristic detection wavelength for each compound (for example, 400 nm for thioxanthrone compounds). The relative molecular mass corresponding to the peak apex of the detected main peak can be measured by liquid chromatography mass spectrometry (LC/MS).

The amount of the photopolymerization initiator is preferably 0.1 mass % to 8 mass %, more preferably 0.5 mass % to 5 mass %, and further preferably 1 mass % to 3 mass % relative to the total amount of the sealant. If the amount of the photopolymerization initiator is 0.1 mass % or more, the photocurability of the sealant is easily improved. If the amount of the photopolymerization initiator is 8 mass % or less, the photopolymerization initiator is not easily eluted into the liquid crystal.

(6) Inorganic particles The sealant may further contain inorganic particles as needed. If the sealant contains inorganic particles, the viscosity of the sealant and the strength and linear expansion of the obtained sealing member are likely to be improved.

Examples of materials of inorganic particles include calcium carbonate, magnesium carbonate, barium sulfate, magnesium sulfate, aluminum silicate, zirconium silicate, iron oxide, titanium oxide, titanium nitride, aluminum oxide (alumina), zinc oxide, silicon dioxide, potassium titanium oxide, kaolin, talc, glass beads, sericite, activated clay, bentonite, aluminum nitride, silicon nitride, etc. The sealant may contain only one type of inorganic particles or may contain two or more types. Among the above, the inorganic particles are preferably silicon dioxide or talc.

The shape of the inorganic particles may be a fixed shape such as spherical, plate-like, needle-like, or an indefinite shape. When the inorganic particles are spherical, the average primary particle size of the inorganic particles is preferably 1.5 μm or less, and the specific surface area is preferably 0.5 m ² /g to 20 m ² /g. The average primary particle size of the inorganic particles can be measured by the laser diffraction method described in Japanese Industrial Standards (JIS) Z8825-1. The specific surface area of the inorganic particles can be measured by the Brunauer-Emmett-Teller method (BET method) described in JIS Z8830.

The content of the inorganic particles is preferably 0.1 mass % to 25 mass %, more preferably 3 mass % to 20 mass %, and even more preferably 5 mass % to 18 mass % relative to the total amount of the sealant. If the content of the inorganic particles is 0.1 mass % or more, the moisture resistance of the obtained sealing member is easily improved, and if it is 25 mass % or less, the coating stability of the sealant is not easily impaired.

(7) Organic particles The sealant may further contain organic particles as needed. If the sealant contains organic particles, it is easy to adjust the elastic modulus of the sealant after light curing.

Examples of organic particles include silicone particles, acrylic particles, styrene particles such as styrene-divinylbenzene copolymers, and polyolefin particles. The sealant may contain only one type of organic particles or two or more types. The average primary particle size of the organic particles is preferably 0.05 μm to 13 μm, more preferably 0.1 μm to 10 μm, and even more preferably 0.1 μm to 8 μm.

In addition, the shape of the organic particles is not particularly limited, but preferably spherical, and more preferably round. The so-called spherical means that the ratio of the minimum value (b) of the diameter of each particle to the maximum value (a) is b/a=0.9 to 1.0. The average primary particle size of the organic particles can be measured by microscopic method, specifically, electron microscope image analysis. In addition, the surface of the organic particles is preferably smooth. If the surface is smooth, the specific surface area is reduced, and the amount of organic particles that can be added to the sealant is increased.

The content of the organic particles is preferably 0.1 mass % to 20 mass %, more preferably 1 mass % to 15 mass %, and further preferably 3 mass % to 12 mass % relative to the total amount of the sealant. If the amount of the organic particles is within this range, the elastic modulus of the sealant after light curing can be easily brought into a desired range.

(8) Others The sealant of the present invention may further include additives such as thermal free radical polymerization initiators, coupling agents such as silane coupling agents, ion scavengers, ion exchange agents, leveling agents, pigments, dyes, sensitizers, plasticizers and defoaming agents as needed.

Examples of silane coupling agents include vinyl trimethoxysilane, γ-(meth)acryloxypropyl trimethoxysilane, γ-glyceryloxypropyl trimethoxysilane, γ-glyceryloxypropyl triethoxysilane, etc. The amount of the silane coupling agent is preferably 0.01 mass% to 6 mass%, more preferably 0.1 mass% to 5 mass%, and further preferably 0.5 mass% to 3 mass% relative to the total amount of the sealant. If the content of the silane coupling agent is 0.01 mass% or more, the obtained sealing component is likely to have sufficient adhesion. Among them, most silane coupling agents have a high residual DC value. Therefore, the amount of the silane coupling agent is preferably 6 mass% or less.

The sealant may further include spacers for adjusting the gap of the liquid crystal display panel.

The total amount of other components is preferably 1 mass % to 50 mass % relative to the total amount of the sealant. If the total amount of other components is 50 mass % or less, the viscosity of the sealant is unlikely to increase excessively, and the coating stability of the sealant is unlikely to be impaired.

(9) Physical properties of sealant The viscosity of the sealant measured by an E-type viscometer at 25°C and 2.5 rpm is preferably 200 Pa·s to 450 Pa·s, and more preferably 300 Pa·s to 400 Pa·s. If the viscosity is within the above range, when a pair of substrates are overlapped by the sealant (sealing pattern), the sealant is easily deformed to fill the gap. Therefore, the gap between a pair of substrates of the liquid crystal display panel can be appropriately controlled.

In addition, from the perspective of the coating properties of the sealant, the thixotropy index (TI (thixotropy index) value) of the sealant is preferably 1.0 to 1.5, and more preferably 1.1 to 1.3. The TI value is obtained by using an E-type viscometer at room temperature (25°C) with the viscosity of the sealant at 0.5 rpm as η1 and the viscosity of the sealant at 5 rpm as η2, and applying these measured values to the following formula (1). TI value = (viscosity η1 at 0.5 rpm (25°C)) / (viscosity η2 at 5 rpm (25°C))···(1)

The residual DC value obtained by mixing the sealant and the liquid crystal as described above and measuring the result is preferably 100 mV or less. In this case, it is preferred to use MLC-7026 manufactured by Merck as the liquid crystal for measurement.

2. Liquid crystal display panel The liquid crystal display panel of the present invention has a pair of substrates, a frame-shaped sealing member disposed between the substrates, and liquid crystal filled between the pair of substrates and inside the frame-shaped sealing member. In the liquid crystal display panel, the sealing member is a cured product of the sealant. The sealing member obtained by the sealant has a high bonding strength with the substrate, and even if the sealing member is thinned, liquid crystal leakage is not likely to occur. Furthermore, the sealant is not likely to contaminate the liquid crystal. Therefore, when the liquid crystal display panel is used, afterimages are not likely to occur.

A pair of substrates (also referred to as "display substrate and counter substrate") are both transparent substrates. Examples of materials for the transparent substrates include glass, polycarbonate, polyethylene terephthalate, polyether ether, and polymethyl methacrylate (PMMA).

A matrix-shaped thin film transistor (TFT), a color filter, a black matrix, etc. are arranged on the surface of the display substrate or the counter substrate. An alignment film is further formed on the surface of the display substrate or the counter substrate. The alignment film contains a known organic alignment agent or an inorganic alignment agent, etc. In addition, the liquid crystal can use a known liquid crystal.

There are generally two methods for manufacturing a liquid crystal display panel: a liquid crystal dropping method and a liquid crystal injection method. However, the method for manufacturing a liquid crystal display panel of the present invention is preferably the liquid crystal dropping method.

The manufacturing method of a liquid crystal display panel using a liquid crystal dropping method includes: 1) a sealing pattern forming step, in which the sealing agent is applied on one of the substrates to form a frame-shaped sealing pattern; 2) a liquid crystal dropping step, in which, when the sealing pattern is not hardened, liquid crystal is dropped into an area surrounded by the sealing pattern on one of the substrates, or into an area surrounded by the sealing pattern on another substrate when the other substrate is facing the one of the substrates; 3) an overlapping step, in which one of the substrates and the other substrate are overlapped with each other via the sealing pattern; and 4) a curing step, in which the sealing pattern is cured.

1) In the sealing pattern forming step, the sealant is applied on one of the substrates. The method of applying the sealant is not particularly limited, and any method that can form a sealing pattern with a desired thickness or width, such as screen printing or application using a dispenser, is not particularly limited, and is the same as the known method of applying the sealant.

In addition, the shape of the sealing pattern formed can be appropriately selected according to the purpose of the liquid crystal display panel, as long as it is a shape that does not leak liquid crystal. For example, it can be set to a rectangular frame shape, but it is not limited to this shape. The line width of the sealing pattern is preferably 0.2 mm to 1.0 mm, and more preferably 0.2 mm to 0.5 mm.

2) In the liquid crystal dropping step, a pair of substrates are placed facing each other in a state where the sealing pattern is not hardened. Here, the state where the sealing pattern is not hardened refers to a state where the curing reaction of the sealant has not proceeded to the gelation point. Furthermore, before the liquid crystal dropping step, in order to suppress the dissolution of the sealant in the liquid crystal, the sealing pattern may be irradiated with light or heated to semi-harden it. In addition, the liquid crystal dropping method is the same as the known liquid crystal dropping method, and the liquid crystal may be dropped on a substrate with a sealing pattern formed thereon, or on a substrate (another substrate) without a sealing pattern formed thereon.

3) In the overlapping step, one substrate is overlapped with the other substrate in a manner of facing each other through the sealing pattern. At this time, the gap between the substrates is controlled so as to be within a desired range.

4) In the curing step, the sealing pattern is cured. There is no particular limitation on the curing method of the sealing pattern, but it is preferably temporarily cured by irradiation with light of a specified wavelength and then formally cured by heating. The sealing pattern can be cured instantly by light irradiation, and the components in the sealant can be suppressed from dissolving in the liquid crystal.

The wavelength of the irradiated light can be appropriately selected according to the type of photopolymerization initiator, and ultraviolet light is preferred. In addition, the light irradiation time also depends on the composition of the sealant, for example, it is about 10 minutes. At this time, the irradiated energy can be an energy of a degree that can cure the (meth) acrylic compound or the (meth) acrylic-epoxy-containing compound.

After irradiation with light, the epoxy compound or the (meth)acrylic-epoxy-containing compound is cured by heating. The heating temperature also depends on the composition of the sealant, but is, for example, 100°C to 150°C, and the heating time is preferably about 2 hours. [Example]

The present invention is described in detail based on the embodiments, but the present invention is not limited to these embodiments.

<Synthesis Example 1> Preparation of photocurable composition 1 (preparation of composition containing methacrylic acid modified epoxy compound) 160 g of liquid bisphenol F type epoxy compound (Epiclon 830-S, manufactured by DIC Corporation, epoxy equivalent 160 g/eq), 0.1 g of polymerization inhibitor (p-methoxyphenol), 0.2 g of catalyst (triethanolamine) and 43.0 g of methacrylic acid were placed in a flask, and dry air was introduced and refluxed at 90°C with stirring, and reacted for 5 hours. The obtained composition was washed 20 times with ultrapure water to obtain a composition containing methacrylic acid modified epoxy compound (composition 1 containing a photocurable compound). The composition of the obtained composition was identified by NMR, and the result was that the epoxy compound with epoxy groups at both ends was 25 mol%, the methacrylic acid-modified epoxy compound having epoxy groups and methacrylic acid groups at the ends was 50 mol%, and the (meth)acrylic acid compound with methacrylic acid groups at both ends was 25 mol%. The obtained composition was separated by a column, and the residual DC value of each was measured by the method described below. The results are shown in Table 1.

<Synthesis Example 2> Preparation of photocurable composition 2 (preparation of composition containing acrylic acid-modified epoxy compound) 190 g of liquid bisphenol A type epoxy compound (Epiclon 850-S, manufactured by DIC Corporation, epoxy equivalent 190 g/eq), 0.1 g of polymerization inhibitor (p-methoxyphenol), 0.2 g of catalyst (triethanolamine) and 36.0 g of acrylic acid were placed in a flask, and dry air was introduced and refluxed at 90°C for 5 hours. The obtained composition was washed 20 times with ultrapure water to obtain a composition containing acrylic acid-modified epoxy compound (photocurable composition 2). The composition of the obtained composition was identified by NMR, and the result was that the epoxy compound with epoxy groups at both ends was 25 mol%, the (meth) acrylic compound having epoxy groups and acrylic groups at the ends was 50 mol%, and the (meth) acrylic compound modified with acrylic groups at both ends was 25 mol%. The obtained composition was separated by a column, and the residual DC value of each was measured by the method described below. The results are shown in Table 1.

[Example 1] 400 parts by weight of the photocurable composition 1, 100 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA (bisphenol A type, residual DC value = 64 mV)), 50 parts by weight of an epoxy compound (850-S, manufactured by DIC (bisphenol A type, residual DC value = 133 mV)), 50 parts by weight of a (meth)acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec (residual DC value = 52 mV)), 80 parts by weight of a (meth)acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF Japan (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these are thoroughly mixed using three rollers to form a uniform liquid, thereby obtaining a sealant.

[Example 2] Except that the photocurable composition 1 is changed to the photocurable composition 2, the sealant is prepared in the same manner as in Example 1.

[Example 3] 400 parts by weight of the photocurable composition 2, 50 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 50 parts by weight of an epoxy compound (Epikote 1004AF, manufactured by Mitsubishi Chemical, bisphenol A type (residual DC value = 57 mV)), 50 parts by weight of an epoxy compound (850-S, manufactured by DIC, bisphenol A type (residual DC value = 133 mV)), 50 parts by weight of a (meth)acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec, (residual DC value = 52 mV)), 80 parts by weight of a (meth) acrylic acid compound (2CL, manufactured by Shin-Nakamura Chemical Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (dihydrazide adipic acid, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of an organic particle (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by mass of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Example 4] 500 parts by weight of the photocurable composition 1, 80 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 50 parts by weight of an epoxy compound (Epikote 1004AF, manufactured by Mitsubishi Chemical, bisphenol A type (residual DC value = 57 mV)), 50 parts by weight of an epoxy compound (850-S, manufactured by DIC, bisphenol A type (residual DC value = 133 mV)), 40 parts by weight of a (meth) acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 130 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 70 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed.

[Example 5] 430 parts by weight of the photocurable composition 2, 150 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 100 parts by weight of a (meth) acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec, bisphenol A type (residual DC value = 52 mV)), 40 parts by weight of a (meth) acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a thermosetting agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 130 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemicals (residual DC value = 51 mV)), 70 parts by weight of organic particles (Fine Particle Polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Industries (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Example 6] 600 parts by weight of the photocurable composition 1, 80 parts by weight of an epoxy compound (Epikote 1004AF, manufactured by Mitsubishi Chemical Co., Ltd., bisphenol A type (residual DC value = 57 mV)), 30 parts by weight of an epoxy compound (850-S, manufactured by DIC Corporation, bisphenol A type (residual DC value = 133 mV)), 50 parts by weight of a thermosetting agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF Corporation (residual DC value = 68 mV)), 130 parts by mass of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemicals Co., Ltd. (residual DC value = 51 mV)), 70 parts by mass of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 20 parts by mass of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Example 7] 500 parts by weight of the photocurable composition 1, 200 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 40 parts by weight of an epoxy compound (850-S, manufactured by DIC, bisphenol A type (residual DC value = 133 mV)), 50 parts by weight of a thermosetting agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 130 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemicals Co., Ltd. (residual DC value = 51 mV)), 50 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Comparative Example 1] 400 parts by weight of the photocurable composition 2, 50 parts by weight of an epoxy compound (850-S, manufactured by DIC Corporation, bisphenol A type (residual DC value = 133 mV)), 100 parts by weight of an epoxy compound (Epogosey NPG, manufactured by Yokkaichi Synthetics Co., Ltd., 1,4-butanediol diglycidyl ether (residual DC value = 300 mV)), 50 parts by weight of a (meth)acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec Co., Ltd. (residual DC value = 52 mV)), 80 parts by weight of a (meth)acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF Japan (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these are thoroughly mixed using three rollers to form a uniform liquid, thereby obtaining a sealant.

[Comparative Example 2] 600 parts by weight of the photocurable composition 1, 80 parts by weight of a (meth) acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a thermosetting agent (dihydrazide adipic acid, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF Japan (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of an organic particle (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by mass of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Comparative Example 3] 400 parts by weight of the photocurable composition 2, 100 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 50 parts by weight of an epoxy compound (Epogosey NPG, manufactured by Yokkaichi Synthetics, 1,4-butanediol diglycidyl ether (residual DC value = 300 mV)), 50 parts by weight of a (meth)acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec (residual DC value = 52 mV)), 80 parts by weight of a (meth)acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Industries, Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 10 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these are thoroughly mixed using three rollers to form a uniform liquid, thereby obtaining a sealant.

[Comparative Example 4] 200 parts by weight of the photocurable composition 1, 40 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 200 parts by weight of an epoxy compound (850-S, manufactured by DIC, bisphenol A type (residual DC value = 133 mV)), 130 parts by weight of a (meth) acrylic compound (Ebecryl 3700, manufactured by Daicel Cytec (residual DC value = 52 mV)), 100 parts by weight of a (meth) acrylic compound (2CL, manufactured by Shin-Nakamura Chemical Industry Co., Ltd. (residual DC value = 73 mV)), 50 parts by weight of a heat curing agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemical Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of organic particles (fine particle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 20 parts by weight of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these are thoroughly mixed using three rollers to form a uniform liquid, thereby obtaining a sealant.

[Comparative Example 5] 340 parts by weight of the photocurable composition 1, 130 parts by weight of an epoxy compound (EP-4010S, manufactured by ADEKA, bisphenol A type (residual DC value = 64 mV)), 200 parts by weight of an epoxy compound (850-S, manufactured by DIC, bisphenol A type (residual DC value = 133 mV)), 50 parts by weight of a thermosetting agent (adipic acid dihydrazide, manufactured by Otsuka Chemical Co., Ltd. (residual DC value = 53 mV)), and 20 parts by weight of a photopolymerization initiator (OXE-01, manufactured by BASF (residual DC value = 68 mV)), 150 parts by weight of inorganic particles (silicon dioxide particles: S-100, manufactured by Nippon Catalyst Chemicals Co., Ltd. (residual DC value = 51 mV)), 90 parts by weight of organic particles (microparticle polymer F351, manufactured by Aica Industries (residual DC value = 55 mV)) and 20 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd. (residual DC value = 431 mV)) were mixed. Then, these were fully mixed using three rolls to form a uniform liquid, thereby obtaining a sealant.

[Evaluation] The sealants obtained in the examples and comparative examples were evaluated as follows.

<Measurement of residual DC value of sealant and liquid crystal> The sealant and liquid crystal were mixed and the residual DC value was measured. 0.1 g of liquid crystal sealant and 1 g of liquid crystal (MLC-7026, manufactured by Merck) were put into a glass bottle and heated at 120°C for 1 hour to obtain a liquid crystal mixture. Then, the liquid crystal mixture was taken out and injected into a glass cell (KSSZ-10/B111M1NSS05, manufactured by EHC) on which an alignment film and a transparent electrode were pre-formed. A voltage of 5 V was applied to the obtained cell for 1 second and short-circuited for 0.1 second, and then the voltage (residual DC value) remaining after 30 seconds was measured using a 6254 type measuring device (manufactured by Toyo Technica). Furthermore, the residual DC value of the liquid crystal alone was measured in the same manner, and the result showed that the residual DC value of the liquid crystal alone was 50 mV.

<Residual DC value measurement of raw materials> The above raw materials were mixed with liquid crystal and the residual DC value was measured. 0.1 g of the compound and 1 g of liquid crystal (MLC-7026, manufactured by Merck) were placed in a glass bottle and heated at 120°C for 1 hour to obtain a liquid crystal mixture. Then, the liquid crystal mixture was taken out and injected into a glass cell (KSSZ-10/B111M1NSS05, manufactured by EHC) on which an alignment film and a transparent electrode were pre-formed. A voltage of 5 V was applied to the obtained cell for 1 second and short-circuited for 0.1 second, and then the voltage (residual DC value) remaining after 30 seconds was measured using a 6254 type measuring device.

<Image afterimage evaluation> Using a dispenser (Shotmaster; manufactured by Musashi Engineering), the sealant was applied to a 40 mm × 45 mm glass substrate (RT-DM88-PIN, manufactured by EHC) on which a transparent electrode and an alignment film were previously formed. Specifically, a 35 mm × 40 mm square seal pattern (cross-sectional area 3500 μm ² ) (main seal) was formed, and the same seal pattern (38 mm × 43 mm square seal pattern) was formed on its periphery.

Next, using a dispenser, a liquid crystal (MLC-7026-000, manufactured by Merck) with a volume equivalent to the internal volume of the bonded panel was precisely dripped into the frame of the main seal. Next, the paired glass substrates were bonded under reduced pressure and then bonded by opening to the air. The two bonded glass substrates were then kept in a light-shielding box for 3 minutes, then irradiated with 100 mJ/ ^cm2 of light with a wavelength of 370 nm to 450 nm, and then heated at 120°C for 1 hour. Polarizing plates were attached to both sides of the obtained substrate to make an evaluation substrate.

The electrodes were connected and a voltage of 10 V was applied so that only half of the evaluation substrate filled with liquid crystal was driven, and the power was turned on at 65°C for 24 hours. Then, the entire surface was driven at 4 V, and the boundary between half-surface drive and full-surface drive was observed under a microscope. The evaluation of residual images was performed as follows based on the state on the boundary of the substrate. In the case of narrow frame, it can be said that only ○ is a range that has no practical problems. ○: No difference is seen on the boundary of the substrate and no residual image is seen △: Residual image is seen on the boundary of the substrate within the range of less than 1 mm from the end of the sealant ×: Residual image is seen on the boundary of the substrate in the part more than 1 mm from the end of the sealant

<Evaluation of the adhesive strength> The sealant was printed on an alkali-free glass of 25 mm × 45 mm × 1 mm thick using a screen plate. The sealing pattern was set to a circular shape with a diameter of 1 mm. Then, a pair of alkali-free glasses were placed on the sealing pattern and fixed with a clamp. The test piece was irradiated with 500 mW/ ^cm2 of ultraviolet light using an ultraviolet light irradiation device (manufactured by Ushio Electric Co., Ltd.) to cure the sealant. At this time, the illuminance energy of the ultraviolet light was set to 3.0 J/ ^cm2 . The test piece in which the sealant was cured by light was heated in an oven at 120°C for 60 minutes to prepare a sample for the adhesive strength measurement.

For this sample, a tensile tester (manufactured by INTESCO) was used, and the tensile speed was set to 2 mm/min. The cured sealant was peeled off in a direction parallel to the bottom surface of the glass to measure the tensile strength of the plane. Here, the strength is then evaluated as follows based on the size of the tensile strength of the plane. In the case of narrow frame, it is better to be △ or above. ○: Tensile strength is 15 MPa or more △: Tensile strength is 10 MPa or more and less than 15 MPa ×: Tensile strength is less than 10 MPa

[Table 1] Molecular weight Residual DC Embodiment Comparison Example 1 2 3 4 5 6 7 1 2 3 4 5 EP-4010S Epoxides 692 64 mV (128%) 100 100 50 80 150 200 100 40 130 Epikote 1004AF Epoxides 1734 57 mV (114%) 50 50 80 850-S Epoxides 340 133 mV (266%) 50 50 50 50 30 40 50 200 200 Epogosey NPG Epoxides 216 300 mV (600%) 100 50 Photocurable composition 1 Epoxides 31286 146 mV (292%) 78 98 117 98 117 39 66 (Meth)acrylic-epoxy-containing compounds 398 105 mV (210%) 201 251 302 251 302 100.5 171 (Meth)acrylic acid compounds 485 63 mV (126%) 121 151 181 151 181 60.5 103 Photocurable composition 2 Epoxides 340 133 mV (266%) 81 81 87 81 81 (Meth)acrylic-epoxy-containing compounds 412 86 mV (172%) 197 197 212 197 197 (Meth)acrylic acid compounds 513 52 mV (104%) 122 122 131 122 122 Ebecryl 3700 (Meth)acrylic acid compounds 513 52 mV (104%) 50 50 50 100 50 50 130 2CL (Meth)acrylic acid compounds 652 73 mV (146%) 80 80 80 40 40 80 80 80 100 Adipic acid dihydrazide Heat hardener 53 mV (106%) 50 50 50 50 50 50 50 50 50 50 50 50 OXE-01 Photopolymerization initiator 68 mV (136%) 20 20 20 20 20 20 20 20 20 20 20 20 Silicon dioxide particles_S-100 Inorganic particles 51 mV (102%) 150 150 150 130 130 130 130 150 150 150 150 150 Microparticle polymer F351 Organic particles 55 mV (110%) 90 90 90 70 70 70 50 90 90 90 90 90 KBM-403 Silane coupling agent 236 431 mV (862%) 10 10 10 10 10 20 10 10 10 10 20 20 Total 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 Epoxide content (mass %) 22.8 23.1 23.1 27.8 23.7 22.7 33.8 23.1 11.7 23.1 27.9 39.6 The proportion of raw materials having a residual DC value within 300% of the residual DC value of liquid crystal alone (50 mV) is 98% by mass or more ○ ○ ○ ○ ○ ○ ○ × ○ × ○ ○ The ratio of epoxy compounds with a molecular weight of 500 or more to the total amount of epoxy compounds (mass %) 43.8 43.3 43.2 46.7 63.3 35.2 59.2 0.0 0.0 43.2 14.3 32.8 Residual DC value of the mixture of sealant and liquid crystal (mV) 80 63 75 90 82 72 95 206 86 110 152 136 Ratio of the residual DC value of the mixture to the residual DC value of the liquid crystal alone (50 mV) (%) 160 126 150 180 164 144 190 412 172 220 304 272 Image Evaluation ○ ○ ○ ○ ○ ○ ○ × ○ △ × △ Then the strength evaluation ○ ○ ○ ○ △ ○ ○ ○ × △ ○ ○

As shown in Table 1, in the case of a sealant containing an epoxy compound, a (meth)acrylic-epoxy-containing compound, a (meth)acrylic compound, a thermosetting agent, and a photopolymerization initiator, and the content of the epoxy compound is 22 mass % to 38 mass %, and the residual DC value of the mixture of the sealant and the liquid crystal is 200% or less relative to the residual DC value of the liquid crystal alone, the residual image evaluation is good and the bonding strength evaluation is also good (Example 1 to Example 7). It is believed that sufficient adhesion is obtained by the prescribed amount of the epoxy compound. In addition, in the case of a sealant with a low residual DC value when mixed with the liquid crystal, it can be said that the components in the sealant are not easily eluted into the liquid crystal.

On the other hand, when the amount of the epoxy compound is less than 22 mass%, the result of the afterimage evaluation is good, but the result of the adhesion test is low (Comparative Example 2). On the other hand, when the amount of the epoxy compound exceeds 38 mass%, although the adhesion is good, the value of the afterimage residual DC tends to increase, and the afterimage evaluation is poor (Comparative Example 5).

In addition, even when the content of the epoxy compound was 22 mass % to 38 mass %, when the residual DC value when the sealant and liquid crystal were mixed was high, the afterimage evaluation was poor (Comparative Example 1, Comparative Example 3, and Comparative Example 4).

This application claims priority based on Japanese Patent Application No. 2020-034974 filed on March 2, 2020. All contents described in the specification of that application are incorporated herein by reference. [Industrial Applicability]

According to the sealant of the present invention, a sealing member having high adhesion to a substrate can be obtained. In addition, the sealant is not easy to contaminate liquid crystal. Therefore, the sealant is very useful as a sealant for manufacturing a sealing member of various liquid crystal display panels.

without

without

Claims (10)

A sealing agent for a liquid crystal dripping method, comprising: an epoxy compound having no polymerizable functional group other than an epoxy group, a (meth)acrylic-epoxy-containing compound having both a (meth)acrylic group and an epoxy group in one molecule, a (meth)acrylic compound having no epoxy group, a thermosetting agent, and a photopolymerization initiator, wherein the content of the epoxy compound is 22 mass % to 38 mass %, and the photopolymerization initiator is an oxime ester compound. The residual DC value of a mixture of a sealant and a liquid crystal composed of MLC-7026 manufactured by Merck in a mass ratio of 1:10 was measured after heating at 120°C for 1 hour, applying a voltage of 5V for 1 second and short-circuiting for 0.1 second, and then measuring it after 30 seconds was less than 200% of the residual DC value of the liquid crystal when it was heated at 120°C for 1 hour, applying a voltage of 5V for 1 second and short-circuiting for 0.1 second, and then measuring it after 30 seconds. The sealing agent for liquid crystal dropping method as described in claim 1, wherein, with respect to each component contained in the sealing agent for liquid crystal dropping method, when each component is mixed with liquid crystal at a mass ratio of 1:10, heated at 120°C for 1 hour, a voltage of 5V is applied for 1 second and short-circuited for 0.1 second, and then the residual DC value is measured after 30 seconds, the residual DC value of the components accounting for 98% by mass or more of the sealing agent for liquid crystal dropping method is 300% or less relative to the residual DC value obtained by heating the liquid crystal at 120°C for 1 hour, applying a voltage of 5V for 1 second and short-circuiting for 0.1 second, and then measuring after 30 seconds. The sealant for liquid crystal dripping method as described in claim 1, wherein the proportion of the component with a molecular weight of 500 or more in the epoxy compound is 25% by mass or more. The sealant for liquid crystal dripping method as described in claim 1, wherein the thermosetting agent is one or more selected from the group consisting of organic acid dihydrazide-based thermolatent curing agents, imidazole-based thermolatent curing agents, amine adduct-based thermolatent curing agents, and polyamine-based thermolatent curing agents. The sealant for liquid crystal dripping method as described in claim 1 further comprises inorganic particles. The sealant for liquid crystal dripping method as described in claim 1 further comprises organic particles. The sealant for liquid crystal dripping method as described in claim 1 further comprises a silane coupling agent. A method for manufacturing a liquid crystal display panel, comprising: a step of applying a sealant for a liquid crystal dripping method as described in any one of claim 1 to claim 7 on one of a pair of substrates to form a sealing pattern; a step of dripping liquid crystal in the area of the sealing pattern of one of the substrates or on the other substrate when the sealing pattern is not hardened; a step of overlapping the one substrate and the other substrate with the sealing pattern interposed therebetween; and a step of hardening the sealing pattern. A method for manufacturing a liquid crystal display panel as described in claim 8, wherein, in the step of hardening the sealing pattern, the sealing pattern is irradiated with light. A method for manufacturing a liquid crystal display panel as described in claim 9, wherein, in the step of hardening the sealing pattern, heating is performed after irradiating light.