KR20200110185A - Sealing agent for display and liquid crystal display - Google Patents

Abstract

The present invention relates to a sealing agent for a display which can be applied to a flexible display or a display having a curved shape. Particularly, the present invention relates to a sealing agent for a display including a compound having a specific structure in the molecule. The sealing agent for a display shows excellent adhesion strength to an adherent and has flexibility compatible with low water permeability, and thus is useful as a sealing agent particularly for a display requiring adhesiveness to an organic film, a flexible display or a display having a curved shape. The sealing agent for a display includes (A) an urethane (meth)acrylate obtained by reacting (a) a polyol having an alicyclic structure, (b) an organic polyisocyanate and (c) a hydroxyl group-containing (meth)acrylate.

Description

Sealing agent for display and liquid crystal display {SEALING AGENT FOR DISPLAY AND LIQUID CRYSTAL DISPLAY}

The present invention relates to a display encapsulant that can be applied to a flexible display or a curved display. Since this display sealing agent can achieve both flexibility and low moisture permeability, it is particularly useful as a flexible display or a curved display sealing agent.

In addition, the sealing agent having a high degree of flexibility as in the present invention is useful in applications requiring high adhesive strength because it has excellent adhesive strength with an adherend.

The sealing agent for displays includes, for example, a sealing agent for liquid crystal displays, a sealing agent for organic EL displays, and an adhesive for touch panels. What is common for these materials is that they are required to have excellent curability and have little outgassing, so that they do not damage the display element.

In addition, in recent years, a curved display or a flexible display has been developed and commercialized. As for the substrate used for such a display, a flexible one such as a plastic film is used instead of a rigid one such as a conventional glass (Patent Document 1).

Against this background, the display encapsulant is required to conform to the warpage of a substrate or the like, that is, to be flexible even after curing.

In addition, a sealing agent having excellent flexibility is also advantageous in adhesive strength. For example, peeling due to impact and destruction of a substrate can be reduced. From this point of view, there is a growing demand for flexibility in encapsulants.

On the other hand, in order to increase the flexibility of the cured product, lowering the crosslinking density of the cured product is an effective means. However, it is common to deteriorate the moisture permeability when the crosslinking density decreases. This is thought to be due to the intrusion of moisture from the loose part of the network. Therefore, in order to ensure low moisture permeability, it is necessary to realize the contrary characteristics that the crosslinking density is not lowered and the flexibility is increased or the crosslinking density is lowered but the moisture permeability is not deteriorated.

Conventionally, from the viewpoint of improving the adhesive strength, the development of an adhesive for a flexible display element has been made (Patent Document 2). However, having sufficient performance to adapt to the flexible substrate has not yet been realized.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-238005 Patent Document 2: Japanese Laid-Open Patent No. 2016-24240

The present invention relates to a display encapsulant that can be applied to a flexible display or a curved display. More specifically, it relates to a display encapsulant using urethane (meth)acrylate made of a polyol having an alicyclic structure. This display encapsulant is useful as a display encapsulant because it has both flexibility and low moisture permeability and excellent adhesive strength.

As a result of close examination, the inventors of the present invention have come to the present invention by discovering that a display encapsulant containing urethane (meth)acrylate made of a polyol having an alicyclic structure has excellent flexibility and low moisture permeability.

In addition, in this specification, "(meth)acrylate" means "acrylate" and/or "methacrylate".

That is, the present invention relates to the following [1] to [12].

[1] A display encapsulant containing (A) urethane (meth)acrylate obtained by reacting (a) a polyol having an alicyclic structure, (b) an organic polyisocyanate, and (c) a hydroxyl-containing (meth)acrylate.

[2] The display sealing agent according to [1], wherein the component (a) is a polyol having a tricyclodecanedimethanol structure.

[3] The sealing agent for a display according to [1] or [2], wherein the component (A) is obtained by further reacting a polyol other than the component (a) as the component (a-1).

[4] The sealing agent for displays according to any one of [1] to [3], further containing the component (B) curable compound.

[5] The display sealing agent according to [4], wherein the component (B) is a partial epoxy (meth)acrylate.

[6] The sealing agent for displays according to any one of the above [1] to [5], further containing the component (C) organic filler.

[7] The display sealing agent according to [6], wherein the component (C) is one or two or more organic fillers selected from the group consisting of urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles.

[8] The sealing agent for displays according to any one of [1] to [7], further containing the component (D) a thermosetting agent.

[9] The sealing agent for displays according to any one of the above [1] to [8], further containing a component (E) photoradical polymerization initiator.

[10] The sealing agent for displays according to any one of [1] to [9], further containing a component (F) a thermal radical polymerization initiator.

[11] The sealing agent for displays according to any one of [1] to [10], which is a liquid crystal sealing agent for a liquid crystal dropping method.

[12] A liquid crystal display sealed with the liquid crystal sealing agent for a liquid crystal dropping method according to [11].

The display encapsulant of the present invention is useful as a display encapsulant because it has both flexibility and low moisture permeability and excellent adhesive strength.

The sealing agent for display of the present invention comprises (a) a polyol having an alicyclic structure, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate (A) urethane (meth)acrylate (hereinafter, only `` Also referred to as "component (A)") is contained.

Component (A) has a flexible skeleton peculiar to a urethane structure, and further, by using a polyol having an alicyclic structure, the cured product is flexible and has low moisture permeability, and has high adhesive strength not only on the glass substrate but also on the alignment layer.

For flexibility, the elastic modulus of the cured product can be used as an index. The elastic modulus of the cured product with a thickness of 100 μm cured under the condition of 130° C. 40 minutes after irradiation with ultraviolet ray 3000 mJ/cm 2 (measurement wavelength: 365 nm) is preferably 200 to 3000 MPa, more preferably 400 to 2000 MPa, and 600 to 1500 MPa It is particularly preferred. The display adhesive in the above range can be said to be preferable in that it can follow the stress applied to the display.

As the low moisture permeability, it is preferable that the moisture permeability is 60 g/m 2 *24 h or less in a cured product having a thickness of 300 μm.

Component (A) can be obtained by synthesizing (a) a polyol having an alicyclic structure, (b) an organic polyisocyanate, and (c) a hydroxyl group-containing (meth)acrylate by a conventional method.

It is preferable to react 1.1 to 2.0 equivalents of isocyanate groups of component (b) with respect to 1 equivalent of hydroxyl groups of the component (a), and particularly preferably react 1.3 to 2.0 equivalents. The reaction temperature is preferably room temperature (25°C) to 100°C.

It is preferable to react 0.95 to 1.1 equivalents of hydroxyl groups in component (c) per equivalent of isocyanate groups in the reactant of component (a) and component (b). The reaction temperature is preferably room temperature (25°C) to 100°C.

The polyol having an alicyclic structure as the component (a) is not particularly limited as long as it has an alicyclic structure in the polyol structure.

Specific examples of component (a) include, for example, cyclohexanedimethanol, norbornanedimethanol, norbornene dimethanol, tricyclodecanedimethanol, pentacyclopentadecandimethanol, adamantane dimethanol, hydrogenated bisphenol A, hydrogenated Bisphenol F, hydrogenated terpeniphenol, and EO, PO, and caprolactone modified products thereof. In improving the adhesion, it is preferable to use an alicyclic structure having 20 or less carbon atoms, and it is preferable to use tricyclodecanedimethanol in the balance of low moisture permeability and flexibility. As a commercial item of tricyclodecane dimethanol, TCD alcohol DM etc. of Celaniz are mentioned, for example.

Further, diols having a crosslinked structure such as norbornane dimethanol, norbornene dimethanol, tricyclodecane dimethanol, and adamantane dimethanol are preferable from the viewpoint of improving water resistance.

In the present invention, it is also a preferred embodiment to use a polyol other than the component (a) as the component (a-1). Specific examples of component (a-1) include hydrogenated polybutadiene polyol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, neopentyl glycol, 1 ,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1 ,5-pentanediol, cyclohexane-1,4-dimethanol, polyethylene glycol, polypropylene glycol, bisphenol A poly(n≒2~20)ethoxydiol, bisphenol A poly(n≒2~20)propoxydiol Diols such as (a-1-1), these diols (a-1-1) and dibasic acids or anhydrides thereof (for example, succinic acid, adipic acid, azelaic acid, dimer acid, isophthalic acid, terephthalic acid, phthalic acid, or Polyesterdiol (a-1-2), which is a reaction product with anhydride), and the like. Preferably, 3-methyl-1,5-pentanediol and its polyester diol are mentioned.

When component (a) and component (a-1) are used together, component (a) in the total amount of component (a) and component (a-1) is usually 3 to 95% by weight, preferably 5 to 50% by weight And more preferably 8 to 20% by weight.

(b) Specific examples of the organic polyisocyanate include tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4 ,4'-cyclohexylmethane diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, dimethyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl Rendiisocyanate, etc. are mentioned. Preferably, tolylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate are mentioned.

(c) As specific examples of the hydroxyl group-containing (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,4-butanediol (meth)acrylate, polyethylene glycol mono( Meth)acrylate, polypropylene glycol mono (meth)acrylate, pentaerythritol tri (meth)acrylate, ε-caprolactone adduct of 2-hydroxyethyl (meth)acrylate, 2-hydroxy-3- Phenyloxypropyl (meth)acrylate, etc. are mentioned. Preferably, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and polyethylene glycol mono (meth) acrylate are mentioned.

Further, the preferred content of the component (A) is usually 5 to 50 mass%, preferably 5 to 30 mass%, and more preferably 10 to 20 mass% of the total amount of the sealing agent for display.

[(B) Curable compound]

The sealing agent for displays of the present invention contains a curable compound (hereinafter, also simply referred to as "component (B)") as component (B).

The component (B) is not particularly limited as long as it is a compound cured by light or heat, but is preferably a component (B-1) (meth)acrylate (hereinafter, also referred to only as component (B-1)). For example, (meth)acrylic ester, epoxy (meth)acrylate, etc. are mentioned.

[(B-1) (meth)acrylate]

Specific examples of (meth)acrylic ester include N-acryloyloxyethylhexahydrophthalimide, acryloylmorpholine, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and cyclo Hexane-1,4-dimethanol mono (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, phenylpolyethoxy (meth)acrylate, 2-hydroxy-3 -Phenyloxypropyl (meth)acrylate, o-phenylphenol monoethoxy (meth)acrylate, o-phenylphenol polyethoxy (meth)acrylate, p-cumylphenoxyethyl (meth)acrylate, isobornyl (Meth)acrylate, tribromophenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 1 ,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonandiol di(meth)acrylate, tricyclodecanedimethanol(meth)acrylate, bisphenol A Polyethoxydi(meth)acrylate, bisphenol A polypropoxydi(meth)acrylate, bisphenol F polyethoxydi(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylic Rate, tris(acryloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, tripentaerythritol hexa (Meth)acrylate, tripentaerythritol penta(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate , Monomers such as diacrylate of an ester of neopentyl glycol and hydroxypivalic acid, and diacrylate of an ε-caprolactone adduct of an ester of neopentyl glycol and hydroxypivalic acid. Preferably, N-acryloyloxyethylhexahydrophthalimide, phenoxyethyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate are mentioned.

Epoxy (meth)acrylate can be obtained by a known method by reaction of an epoxy resin and (meth)acrylic acid. Although it does not specifically limit as an epoxy resin used as a raw material, A bifunctional or more epoxy resin is preferable and, for example, resorcin diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, Phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycy Diglyci of difunctional phenols such as dilamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, phenol novolak type epoxy resin having a triphenolmethane skeleton, and other bifunctional phenols such as catechol and resorcinol And diglycidyl ether products of difunctional alcohols, halides thereof, and hydrogenated products. Among these, a bisphenol A type epoxy resin and resorcin diglycidyl ether are preferable from the viewpoint of liquid crystal contamination. In addition, the ratio of the epoxy group and the (meth)acryloyl group is not limited and is appropriately selected from the viewpoint of process suitability.

Moreover, partial epoxy (meth)acrylate which makes a part of an epoxy group acrylic ester is used suitably. The ratio of acrylation in this case is preferably about 30 to 70%.

Component (B-1) may be used alone or in combination of two or more. In the resin composition of the present invention, when using the component (B-1), it is usually 10 to 80% by mass, preferably 20 to 70% by mass, based on the total amount of the resin composition.

[(B-2) Epoxy resin]

As an aspect of the present invention, it is more preferable that the component (B) further contains the component (B-2) epoxy resin (hereinafter, also referred to only as component (B-2)).

The epoxy resin is not particularly limited, but a bifunctional or higher epoxy resin is preferred, and examples include resorcin diglycidyl ether, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, and phenol novolac. Type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolac type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidylamine type Epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, phenol novolac type epoxy resin having a triphenolmethane skeleton, and diglycidyl ether products of bifunctional phenols such as catechol and resorcinol And diglycidyl ether products of difunctional alcohols, halides thereof, and hydrogenated products. Among these, a bisphenol A type epoxy resin and resorcin diglycidyl ether are preferable from the viewpoint of liquid crystal contamination.

Component (B-2) may be used alone, or two or more types may be used. In the resin composition of the present invention, when using the component (B-2), it is usually 5 to 50% by mass, preferably 5 to 30% by mass, based on the total amount of the resin composition.

[(C) Organic filler]

The sealing agent for displays of the present invention may contain an organic filler (hereinafter, also simply referred to as "component (C)") as component (C). Examples of the organic filler include urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles. Moreover, as silicone fine particles, KMP-594, KMP-597, KMP-598 (made by Shin-Etsu Chemical Industries), Trefill ^RTM E-5500, 9701, EP-2001 (made by Tore Dow Corning) are preferable, and as urethane fine particles, JB- 800T, HB-800BK (Negami Kogyo Co., Ltd.), styrene fine particles are preferably Lavalon ^RTM T320C, T331C, SJ4400, SJ5400, SJ6400, SJ4300C, SJ5300C, SJ6300C (made by Mitsubishi Chemical), and as styrene olefin fine particles, Septon ^RTM SEPS2004, SEPS2063 is preferred.

These organic fillers may be used alone or in combination of two or more. Further, two or more types may be used to form a core shell structure. Among these, acrylic fine particles and silicone fine particles are preferable.

In the case of using the acrylic fine particles, it is preferable that it is an acrylic rubber having a core-shell structure composed of two types of acrylic rubber, and particularly preferably, the core layer is n-butyl acrylate and the shell layer is methyl methacrylate. This is the Zepiak ^RTM F-351 and is sold from Aika Kogyo Corporation.

Further, examples of the silicone fine particles include organopolysiloxane crosslinked powder, straight chain crosslinked dimethylpolysiloxane powder, and the like. Further, examples of the composite silicone rubber include those obtained by coating a silicone resin (for example, a polyorganosilsesquioxane resin) on the surface of the silicone rubber. Among these fine particles, particularly preferred are silicone rubbers of straight-chain dimethylpolysiloxane crosslinked powder or composite silicone rubber fines of silicone resin-coated straight-chain dimethylpolysiloxane crosslinked powder. These may be used individually, and 2 or more types may be used together. Further, preferably, the shape of the rubber powder is a spherical shape with a small increase in viscosity after addition. In the case of using the component (C) in the sealing agent for displays of the present invention, it is usually 5 to 50% by mass, preferably 5 to 40% by mass, based on the total amount of the display sealing agent.

[(D) Thermal curing agent]

The display encapsulant of the present invention can improve reactivity by adding a thermosetting agent (hereinafter, also referred to only as "component (D)") as component (D).

Examples of the component (D) include compounds having a carboxyl group bonded to an aromatic ring in the molecule, polyvalent amines, polyhydric phenols, and organic acid hydrazide. However, it is not limited to these. For example, aromatic hydrazide terephthalic acid dihydrazide, isophthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 2,6-pyridine dihydrazide, 1,2,4-benzene trihydrazide, 1 , 4,5,8-naphthoic acid tetrahydrazide, pyromellitic acid tetrahydrazide, and the like. In addition, if it is an aliphatic hydrazide, for example, formhydrazide, acetohydrazide, propionic acid hydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimesandi Hydrazide, sebacic acid dihydrazide, 1,4-cyclohexanedihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, iminodiacetate dihydrazide, N,N'-hexamethylenebissemicarbazide, citric acid Hydantoin skeletons such as trihydrazide, nitriloacetate trihydrazide, cyclohexanetricarboxylic acid trihydrazide, and 1,3-bis(hydrazinocarbonoethyl)-5-isopropylhydantoin, preferably valinehydran Dihydrazide, tris(1-hydrazinocarbonylmethyl)isocyanurate, tris(2-hydrazinocarbonylethyl)isocyanu having a toin skeleton (a skeleton in which the carbon atom of the hydantoin ring is substituted with an isopropyl group) Rate, tris(1-hydrazinocarbonylethyl)isocyanurate, tris(3-hydrazinocarbonylpropyl)isocyanurate, bis(2-hydrazinocarbonylethyl)isocyanurate, etc. are mentioned. have. In the balance of curing reactivity and potential, preferably isophthalic acid dihydrazide, malonic acid dihydrazide, adipic acid dihydrazide, tris(1-hydrazinocarbonylmethyl)isocyanurate, tris(1-hydrazinocarbonyl) Ethyl) isocyanurate, tris(2-hydrazinocarbonylethyl)isocyanurate, tris(3-hydrazinocarbonylpropyl)isocyanurate, particularly preferably tris(2-hydrazinocarbonyl) Ethyl) isocyanurate.

As the component (D), it is preferable to use a compound having a carboxyl group bonded to an aromatic ring in the molecule. For example, 4-hydroxybenzoic acid, thiosalicylic acid, terephthalic acid, citrazinic acid, 4-aminobenzoic acid, 4-(aminomethyl ) Benzoic acid and 2-mercaptonicotinic acid are mentioned.

Component (D) may be used alone or in combination of two or more. In the case of using the component (D) in the sealing agent for a display of the present invention, it is usually 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the total amount of the display sealing agent.

The display encapsulant of the present invention can further improve reactivity by adding a curing catalyst. Although amines and imidazoles are mentioned as a curing catalyst, imidazoles are especially suitable. As imidazoles, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2 -Phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2 -Undecylimidazole, 2,4-diamino-6 (2'-methylimidazole (1')) ethyl-s-triazine, 2,4-diamino-6 (2'-undecylic acid) Midazole (1')) ethyl-s-triazine, 2,4-diamino-6 (2'-ethyl-4-methylimidazole (1')) ethyl-s-triazine, 2,4- Diamino-6 (2'-methylimidazole (1')) ethyl-s-triazine/isocyanuric acid adduct, 2-methylimidazole isocyanuric acid 2:3 adduct, 2- Phenylimidazole isocyanuric acid adduct, 2-phenyl-3,5-dihydroxymethylimidazole, 2-phenyl-4-hydroxymethyl-5-methylimidazole, 1-cyanoethyl- 2-phenyl-3,5-dicyanoethoxymethylimidazole, and the like.

[(E) Photoradical polymerization initiator]

The sealing agent for displays of the present invention may contain a photoradical polymerization initiator (hereinafter, also referred to only as "component (E)") as component (E). The photo-radical polymerization initiator is not particularly limited as long as it is a compound that generates a radical or an acid upon irradiation with ultraviolet or visible light to initiate a chain polymerization reaction. For example, benzyldimethylketal, 1-hydroxycyclohexylphenylketone, diethylti Oxantone, benzophenone, 2-ethylanthraquinone, 2-hydroxy-2-methylpropiophenone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, 2, 4,6-trimethylbenzoyldiphenylphosphine oxide, camphorquinone, 9-fluorenone, diphenyldisulfide, etc. are mentioned. Specifically, IRGACURE ^RTM 651, 184, 2959, 127, 907, 369, 379EG, 819, 784, 754, 500, OXE01, OXE02, OXE03, OXE04, DAROCURE ^RTM 1173, LUCIRIN ^RTM TPO (all manufactured by BASF), Say Quol ^RTM Z, BZ, BEE, BIP, BBI (all manufactured by Seiko Chemical Co., Ltd.), etc. are mentioned. Among these, preferred are oxime ester initiators IRGACURE ^RTM OXE01, OXE02, OXE03, and OXE04.

In addition, from the viewpoint of liquid crystal contamination, it is preferable to use one having a (meth)acryl group in the molecule, for example, 2-methacryloyloxyethyl isocyanate and 1-[4-(2-hydroxyethoxy)-phenyl The reaction product of ]-2-hydroxy-2methyl-1-propan-1-one is suitably used. This compound can be prepared by the method described in International Publication No. 2006/027982.

In the case of using the component (E) in the sealing agent for a display of the present invention, it is usually 0.001 to 3% by mass, preferably 0.002 to 2% by mass, based on the total amount of the display sealing agent.

[(F) Thermal radical polymerization initiator]

The sealing agent for a display of the present invention contains (F) a thermal radical polymerization initiator (hereinafter, also referred to only as "component (F)") to improve curing speed and curability.

The thermal radical polymerization initiator is not particularly limited as long as it is a compound that generates radicals by heating to initiate a chain polymerization reaction, but includes organic peroxides, azo compounds, benzoin compounds, benzoin ether compounds, acetophenone compounds, benzopinacol, etc. And benzopinacol is suitably used. For example, as an organic peroxide, Kayamek ^RTM A, M, R, L, LH, SP-30C, Pacadox CH-50L, BC-FF, Kadox B-40ES, Pacadox 14, Trigonox ^RTM 22-70E, 23-C70, 121, 121-50E, 121-LS50E, 21-LS50E, 42, 42LS, Kayester ^RTM P-70, TMPO-70, CND-C70, OO-50E, AN, Kayabutyl ^RTM B, Parkadox 16, Kayacarbon ^RTM BIC-75, AIC-75 (made by Kayaku Akzo Co., Ltd.), Permec ^RTM N, H, S, F, D, G, Perhexa ^RTM H, HC, TMH, C, V, 22, MC, Percure ^RTM AH, AL, HB, Perbutyl ^RTM H, C, ND, L, Percumyl ^RTM H, D, Peroyl ^RTM IB, IPP, Perocta ^RTM ND (manufactured by Nichiyu Corporation), etc. It can be obtained as a commercial item.

In addition, as an azo compound, VA-044, 086, V-070, VPE-0201, VSP-1001 (made by Wako Junyaku Kogyo Corporation), etc. can be obtained as a commercial item.

The content of the component (F) is preferably 0.0001 to 10% by mass, more preferably 0.0005 to 5% by mass, and particularly preferably 0.001 to 3% by mass, based on the total amount of the sealing agent for a display of the present invention.

Additives, such as an inorganic filler, a silane coupling agent, a radical polymerization inhibitor, a pigment, a leveling agent, a defoaming agent, and a solvent, may be added to the display sealing agent of the present invention, if necessary.

[Inorganic filler]

As the inorganic filler, silica, silicon carbide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, mica, talc, clay, alumina, magnesium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, calcium silicate, silicate Aluminum, lithium aluminum silicate, zirconium silicate, barium titanate, glass fiber, carbon fiber, molybdenum disulfide, asbestos, and the like, preferably fused silica, crystalline silica, silicon nitride, boron nitride, calcium carbonate, barium sulfate, sulfuric acid Calcium, mica, talc, clay, alumina, aluminum hydroxide, calcium silicate, and aluminum silicate are exemplified, but silica, alumina, and talc are preferable. You may mix and use 2 or more types of these inorganic fillers.

If the average particle diameter of the inorganic filler is too large, it becomes a factor of defects such as difficulty in forming a gap during bonding of the upper and lower glass substrates when manufacturing a narrow gap liquid crystal display cell, so 2000 nm or less is appropriate, preferably 1000 nm or less. , More preferably 300 nm or less. Further, the preferred lower limit is about 10 nm, more preferably about 100 nm. The particle diameter can be measured with a laser diffraction/scattering particle size distribution analyzer (dry type) (made by Seishin Corporation; LMS-30).

In the case of using an inorganic filler in the sealing agent for displays of the present invention, it is usually 5 to 50 mass%, preferably 5 to 40 mass%, based on the total amount of the display sealing agent. When the content of the inorganic filler is lower than 5% by mass, the adhesive strength to the glass substrate is lowered, and the moisture resistance reliability is also deteriorated, so the decrease in the adhesive strength after moisture absorption may also increase. In addition, when the content of the inorganic filler is more than 50% by mass, it is difficult to collapse because the content of the filler is too large, and formation of a gap in the liquid crystal cell may be impossible.

[Silane coupling agent]

As the silane coupling agent, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)3-aminopropylmethyltrime Oxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N-(2-(vinylbenzylamino)ethyl)3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, etc. are mentioned. These silane coupling agents, as KBM series, KBE series, etc., are sold by Shin-Etsu Chemical Co., Ltd. and the like, and are therefore readily available from the market. In the sealing agent for displays of the present invention, when a silane coupling agent is used, 0.05 to 3% by mass of the total amount of the sealing agent for displays is suitable.

[Radial polymerization inhibitor]

The radical polymerization inhibitor is not particularly limited as long as it reacts with a radical generated from a photo-radical polymerization initiator or a thermal radical polymerization initiator to prevent polymerization, and a quinone-based, piperidine-based, hindered phenol-based, nitroso-based, etc. Can be used. Specifically, naphthoquinone, 2-hydroxynaphthoquinone, 2-methylnaphthoquinone, 2-methoxynaphthoquinone, 2,2,6,6-tetramethylpiperidine-1-oxyl, 2, 2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl, 2,2,6,6-tetramethyl-4-methoxypiperidin-1-oxyl, 2,2,6,6 -Tetramethyl-4-phenoxypiperidin-1-oxyl, hydroquinone, 2-methylhydroquinone, 2-methoxyhydroquinone, parabenzoquinone, butylated hydroxyanisole, 2,6-di-t- Butyl-4-ethylphenol, 2,6-di-t-butylcresol, stearylβ-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t) -Butylphenol), 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl], 2,4,8 ,10-tetraoxaspiro[5,5]undecane, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenylpropionate)methane], 1, 3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-sec-triazine-2,4,6-(1H,3H,5H)trione, paramethoxy Aluminum salts of phenol, 4-methoxy-1-naphthol, thiodiphenylamine, N-nitrosophenylhydroxyamine, brand name Adecastab LA-81, brand name Adecastab LA-82 (made by Adeka Corporation), etc. Although can be mentioned, it is not limited to these. Among these, naphthoquinone-based, hydroquinone-based, nitroso-based, and piperazine-based radical polymerization inhibitors are preferred, and naphthoquinone, 2-hydroxynaphthoquinone, hydroquinone, 2,6-di-tert-butyl-P -Cresol, Polytop 7300P (manufactured by Hakuto Corporation) is more preferable, and Polytop 7300P (manufactured by Hakuto Corporation) is most preferable.

The content of the radical polymerization inhibitor is preferably 0.0001 to 1% by mass, more preferably 0.001 to 0.5% by mass, and particularly preferably 0.01 to 0.2% by mass, based on the total amount of the sealing agent for a display of the present invention.

As an example of a method of obtaining the sealing agent for a display of the present invention, there is a method shown below. First, the component (E) is heated and dissolved in the components (A) and (B) as necessary. Next, after cooling to room temperature, if necessary, components (C), (D), (F), inorganic fillers, silane coupling agents, antifoaming agents and leveling agents, solvents, etc. are added, and a known mixing device such as 3 rolls , By uniformly mixing by a sand mill, a ball mill, etc. and filtering through a metal mesh, the sealing agent for a display of the present invention can be manufactured.

Further, the display sealing agent of the present invention is very useful as an adhesive for liquid crystal display cells, particularly as a liquid crystal sealing agent. An example is shown below about a liquid crystal display cell when the sealing agent for displays of this invention is used as a liquid crystal sealing agent.

In the liquid crystal display cell manufactured by using the adhesive for liquid crystal display cells of the present invention, a pair of substrates having predetermined electrodes formed on the substrate are opposed to each other at predetermined intervals, and the periphery is sealed with the liquid crystal sealing agent of the present invention, Liquid crystal is enclosed. The kind of liquid crystal to be encapsulated is not particularly limited. Here, the substrate is composed of a combination of a substrate made of glass, quartz, plastic, silicon, or the like in which at least one of the substrates has light transmission. As the manufacturing method, after adding a spacer (gap control material) such as glass fiber to the liquid crystal sealing agent of the present invention, after applying the liquid crystal sealing agent to one of the pair of substrates using a dispenser or a screen printing device, etc. Temporarily cure at 80 to 120°C as necessary. Thereafter, liquid crystal is dripped inside the weir of the liquid crystal sealing agent, and the other glass substrate is stacked in a vacuum to form a gap. The liquid crystal display cell of the present invention can be obtained by curing at 90 to 130° C. for 30 minutes to 2 hours after the gap is formed. In addition, in the case of using as a light-heat combination type, an ultraviolet ray is irradiated to the liquid crystal sealing part by an ultraviolet irradiator to cause photocuring. The ultraviolet irradiation amount is preferably 500 to 6000 mJ/cm 2, more preferably 1000 to 4000 mJ/cm 2 (measurement wavelength: 365 nm). Thereafter, if necessary, the liquid crystal display cell of the present invention can be obtained by curing at 90 to 130° C. for 30 minutes to 2 hours. The liquid crystal display cell of the present invention thus obtained has no display defects due to liquid crystal contamination, and has excellent adhesion and moisture resistance reliability. Examples of the spacer include glass fibers, silica beads, and polymer beads. The diameter varies depending on the purpose, but is usually 2 to 8 μm, preferably 4 to 7 μm. The amount used is usually 0.1 to 4 parts by mass, preferably 0.5 to 2 parts by mass, and more preferably about 0.9 to 1.5 parts by mass based on 100 parts by mass of the liquid crystal sealing agent of the present invention.

The sealing agent for a display of the present invention is very suitable for use in adhesive applications in fields requiring curability, adhesion to other adherends, and reliability in moisture and heat resistance. For example, it is a liquid crystal sealing agent, a sealing agent for organic EL, and an adhesive agent for touch panels.

Example

Hereinafter, the present invention will be described in more detail by examples, but the present invention is not limited to the examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on mass.

[Synthesis Example 1]

3-methyl-1,5-pentanediol and sebacic acid polyester polyol (Kuraray Co., Ltd. P-2050, hydroxyl value 56.8 mgKOH/g) 987.9 g, tricyclo in a flask equipped with a thermometer, cooling tube, and stirring device. 98.2 g of decane dimethanol (TCD alcohol DM manufactured by Celanese, molecular weight 196.3), 444.6 g of isophorone diisocyanate (VESTANAT IPDI, molecular weight 222.3 manufactured by Evonik) were added and reacted at 80°C.

The isocyanate content at this time was determined by adding an excess amine and titrating back with hydrochloric acid, and it was confirmed that the value was in the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value.

Next, 0.9 g of metoquinone (polymerization inhibitor), 239.2 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.5 g of dibutyltin dilaurate (catalyst) were added, followed by stirring at 80° C. and isocyanate as an infrared absorption spectrum. The reaction was carried out until the absorption spectrum of the group (2280 cm ^-1 ) disappeared to obtain a urethane acrylate having a weight average molecular weight of 6600.

[Synthesis Example 2]

In a flask equipped with a thermometer, cooling tube, and stirring device, polycaprolactonediol (Flaxel 220 manufactured by Daicel Corporation, hydroxyl value 56.7mgKOH/g) 1979.2g, isophorone diisocyanate (VESTANAT IPDI manufactured by Evonik, molecular weight 222.3) 400.1 g was added and reacted at 80°C.

The isocyanate content at this time was determined by adding an excess amine and titrating back with hydrochloric acid, and it was confirmed that the value was in the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value.

Next, 1.3 g of metoquinone (polymerization inhibitor), 191.4 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.8 g of dibutyltin dilaurate (catalyst) were added, followed by stirring at 80° C. and isocyanate as an infrared absorption spectrum. The reaction was carried out until the absorption spectrum of the group (2280 cm ^-1 ) disappeared to obtain a urethane acrylate having a weight average molecular weight of 11100.

[Synthesis Example 3]

Hydrogenated polybutadiene polyol (GI-1000 manufactured by Nippon Soda Co., Ltd., 67.2 mgKOH/g hydroxyl value) 835.0 g, tricyclodecanedimethanol (Celaniz TCD alcohol DM, molecular weight) in a flask equipped with a thermometer, a cooling tube, and a stirring device. 196.3) 98.2 g and 444.6 g of isophorone diisocyanate (VESTANAT IPDI, molecular weight 222.3 manufactured by Evonik) were added and reacted at 80°C.

The isocyanate content at this time was determined by adding an excess amine and titrating back with hydrochloric acid, and it was confirmed that the value was in the range of plus or minus 2% of the residual amount of isocyanate determined from the calculated value.

Next, 0.8 g of metoquinone (polymerization inhibitor), 239.2 g of 2-hydroxyethyl acrylate (molecular weight 116.1), and 0.5 g of dibutyltin dilaurate (catalyst) were added, followed by stirring at 80° C. and isocyanate as an infrared absorption spectrum. The reaction was carried out until the absorption spectrum of the group (2280 cm ^-1 ) disappeared to obtain a urethane acrylate having a weight average molecular weight of 5700.

[Synthesis Example 4]

100 parts (0.28 mol) of commercially available benzopinacol (manufactured by Tokyo Kasei) was dissolved in 350 parts of dimethylformaldehyde. To this, 32 parts (0.4 mol) of pyridine as a base catalyst and 150 parts (0.58 mol) of BSTFA (made by Shin-Etsu Chemical Industries) were added as a silylating agent, and the mixture was heated to 70° C. and stirred for 2 hours. The resulting reaction solution was cooled and stirred, 200 parts of water was added to precipitate the product, and unreacted silylating agent was deactivated. The precipitated product was separated by filtration and washed sufficiently with water. Next, the obtained product was dissolved in acetone, and water was added to recrystallize and purified. 105.6 parts (yield 88.3%) of the target 1,2-bis(trimethylsiloxy)-1,1,2,2-tetraphenylethane were obtained.

[Examples 1 to 2, Comparative Examples 1 to 2]

Components (A), (B), (O) are mixed in the ratio shown in Table 1 below, and component (F) is heated and dissolved at 90°C, and then cooled to room temperature, and components (C), (D), ( After E) and (O) were added and stirred, the mixture was dispersed with a three roll mill and filtered through a metal mesh (635 mesh) to prepare a display encapsulant.

[evaluation]

[Adhesion strength]

The glass substrate was spin-coated with an alignment film liquid (product of Nissan Chemical Industries, Ltd.: RN2880), temporary baking was performed on a hot plate at 80°C for 3 minutes, and baked in an oven at 230°C for 30 minutes. Further, the substrate to which the alignment film was attached was irradiated with ultraviolet rays of 500 mJ/cm 2 (measurement wavelength: 254 nm) by a UV irradiator, and further baked in a 230°C oven for 30 minutes.

1 g of 5 μm glass fiber was added as a spacer to 100 g of the display encapsulant prepared in Examples and Comparative Examples, followed by mixing and stirring. On the glass substrate coated with the alignment layer, this display encapsulant is applied in a form that reproduces the corners of 1 cm x 1 cm, and the facing alignment layer coating substrates are put together, and the measurement wavelength is 3000 mJ/cm 2 (measurement wavelength: 365 nm). After irradiation with ultraviolet rays, it was put into an oven and thermally cured at 130°C for 40 minutes. The peel adhesion strength of the alignment film-coated glass substrate was measured by pressing a corner portion with a bond tester (Seishin Shoji Co., Ltd. product: SS-30WD). The strength is shown in Table 1.

In addition, the results are shown in Table 1 also about the adhesive strength measured on the glass substrate to which the alignment film was not applied.

[Humidity]

The display encapsulant prepared in Examples and Comparative Examples was inserted into a polyethylene terephthalate (PET) film to form a 300 μm-thick thin film, which was irradiated with ultraviolet rays of 3000 mJ/cm 2 (measurement wavelength: 365 nm) by a UV irradiator and then put into an oven. Then, it was thermally cured at 130° C. for 40 minutes, and the PET film was peeled off after curing to obtain a sample. The moisture permeability at 60°C and 90% of the sample was measured with a moisture permeability meter (Lessy's product: L80-5000). Table 1 shows the results.

[Elastic modulus]

The display encapsulant prepared in Examples and Comparative Examples was inserted into a polyethylene terephthalate (PET) film to form a thin film with a thickness of 100 μm, and irradiated with ultraviolet rays of 3000 mJ/cm 2 (measurement wavelength: 365 nm) by a UV irradiator and put into an oven Then, it was thermally cured at 130° C. for 40 minutes, and the PET film was peeled off after curing to obtain a sample. The sample was measured by performing a tensile test at a test rate of 5 mm/min at room temperature (22°C) using a Tensilon universal testing machine (manufactured by A&D Co., Ltd., RTG-1210). Table 1 shows the results.

A-1: Urethane acrylate obtained in Synthesis Example 1

B-1-1: partial acrylate of bisphenol A type epoxy resin

(Example of synthesis by a general synthesis method: Reaction of acrylic acid in Japanese Laid-Open Patent No. 2016-24243 with 50% equivalent)

B-1-2: Orthophenylphenoxyethyl acrylate (MIWON's product: Miramer M-1142)

C-1: Polymethacrylic acid ester-based organic fine particles (Aika Co., Ltd. product brand name "F-351S")

E-1: Tris (2-hydrazinocarbonylethyl) isocyanurate finely pulverized

(Nippon Finechem Co., Ltd.: HCIC, finely pulverized to an average particle diameter of 1.5μm with a jet mill)

F-1: Irgacure OXE04 (product of BASF)

F-2: 2,4-diethyl thioxanthone (Nippon Kayaku Co., Ltd. product brand name "Kayacure DETX-S")

G-1: 1,2-bis(trimethylsiloxy)-1,1,2,2-tetraphenylethane

(Synthesis Example 4 What was finely pulverized to an average of 1.9 μm with a jet mill)

O-1: Urethane acrylate obtained in Synthesis Example 2

O-2: Urethane acrylate obtained in Synthesis Example 3

O-3: Nitroso-based piperidine derivative (Hakuto Co., Ltd. product: Polytop 7300P)

O-4: Tris (3-carboxyethyl) isocyanurate (Shikoku Kasei Co., Ltd. product: CIC acid)

O-5: 3-glycidoxypropyltrimethoxysilane (JNC Co., Ltd. product: Sylla Ace S-510)

From the results of Table 1, it was confirmed that the sealing agent for a display of the present invention has both flexibility and low moisture permeability, and excellent adhesion strength.

The display encapsulant of the present invention has excellent adhesive strength with an adherend and has both flexibility and low moisture permeability, so it is particularly useful as an encapsulant for displays, flexible displays, and curved displays requiring adhesion to organic films. Do.

Claims (12)

Component (a) a polyol having an alicyclic structure and a component (b) an organic polyisocyanate and a component (c) obtained by reacting a hydroxyl-containing (meth)acrylate, a component (A) a sealing agent for a display containing urethane (meth)acrylate . The method according to claim 1,
The component (a) is a polyol having a tricyclodecanedimethanol structure, a sealing agent for a display. The method according to claim 1,
The sealing agent for a display, wherein the component (A) is obtained by further reacting a polyol other than the component (a) as component (a-1). The method according to claim 1,
Component (B) A sealing agent for displays further containing a curable compound. The method of claim 4,
The component (B) is a partially epoxy (meth) acrylate. The method according to claim 1,
Component (C) a sealing agent for a display further containing an organic filler. The method of claim 6,
The component (C) is one or more organic fillers selected from the group consisting of urethane fine particles, acrylic fine particles, styrene fine particles, styrene olefin fine particles, and silicone fine particles. The method according to claim 1,
The sealing agent for displays further containing the component (D) a thermosetting agent. The method according to claim 1,
Component (E) A sealing agent for displays further containing a photo radical polymerization initiator. The method according to claim 1,
Component (F) a sealing agent for a display further containing a thermal radical polymerization initiator. The method according to any one of claims 1 to 10,
A sealing agent for a display that is a liquid crystal sealing agent for a liquid crystal dropping method. A liquid crystal display sealed by the sealing agent for displays according to claim 11.