Sealant for flexible ghlc elements

Abstract

Provided is a sealing agent for flexible GHLC elements, which has excellent adhesion to a thin film with an oriented film even under high-temperature conditions immediately after irradiation with light. The present invention is a sealing agent for flexible GHLC elements, which contains a curable resin and a photopolymerization initiator, a cured product of the sealing agent for flexible GHLC elements has a glass transition temperature of 60°C or lower, the cured product has a storage modulus at 25°C of 500 MPa or lower, and the cured product has a storage modulus at 80°C of 0.01 MPa or higher.

Description

Technical Field

[0001] This invention relates to sealants for flexible GHLC components. Background Technology

[0002] Liquid crystal dimming elements, which change the transmittance of light by applying voltage, are widely used. Liquid crystal dimming elements control the amount of light transmitted by changing the orientation of liquid crystal molecules through a change in the potential difference between transparent electrode layers, exhibiting excellent responsiveness. Among such liquid crystal dimming elements, GHLC elements, which contain dichroic pigments as guests and liquid crystal molecules as hosts, are known. In recent years, flexible GHLC elements manufactured by thin-film bonding have gained attention, replacing conventional GHLC elements manufactured by glass panel bonding. For example, Patent Document 1 discloses a guest-host type liquid crystal dimming element comprising: a pair of substrates having transparent electrodes, and a liquid crystal layer sandwiched between the pair of substrates and containing host liquid crystal and dichroic pigment, wherein a transparent thin-film material having a liquid crystal alignment film is used as the substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2019 / 208765 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] As a manufacturing method for liquid crystal elements, liquid crystal droplet deposition has become the mainstream. In liquid crystal droplet deposition, a frame-shaped sealing pattern is first formed by coating a sealant onto a substrate. Then, while the sealant is not yet cured, tiny droplets of liquid crystal are added into the frame of the sealing pattern. After bonding other substrates under vacuum, the sealant is cured to manufacture the liquid crystal element. In this liquid crystal droplet deposition method, the amount of sealant applied, which contributes to substrate adhesion, is extremely small. Therefore, in flexible GHLC elements using films with alignment films, which are difficult to bond, as substrates, a sealant with excellent adhesion to the alignment film is required. Furthermore, typically, films with alignment films are temporarily fixed to a rigid support layer using an adhesive, and then peeled off from the support layer after being irradiated with light used to cure the sealant. At this point, conventional sealants exhibit almost no adhesion immediately after light exposure. Therefore, even if it is desired to peel the temporarily fixed alignment film from the support layer immediately after light exposure, it is sometimes impossible to peel it off from the support layer, and instead, peeling occurs between the bonded alignment films. Furthermore, in the manufacture of liquid crystal elements, a high-temperature lamination process is usually performed after the sealant curing process, but conventional sealants sometimes fail to maintain adhesion and peel off during this lamination process.

[0008] The object of the present invention is to provide a sealant for flexible GHLC elements that exhibits excellent adhesion to films with oriented films, even immediately after irradiation and under high temperature conditions.

[0009] Methods for solving problems

[0010] This disclosure 1 is a sealant for flexible GHLC elements, which contains a curable resin and a photopolymerization initiator. The glass transition temperature of the cured sealant for flexible GHLC elements is below 60°C, the storage modulus of the cured material at 25°C is below 500 MPa, and the storage modulus of the cured material at 80°C is above 0.01 MPa.

[0011] This disclosure 2 is a sealant for flexible GHLC elements according to disclosure 1, wherein the curable resin contains a monofunctional (meth)acrylic acid compound having one (meth)acryloyl group in one molecule, and the content of the monofunctional (meth)acrylic acid compound in 100 parts by mass of the curable resin is 50 parts by mass or more.

[0012] This disclosure 3 is a sealant for flexible GHLC elements according to disclosure 2, wherein the curable resin comprises a monofunctional (meth)acrylic compound with a glass transition temperature of 20°C or less.

[0013] This disclosure 4 is a sealant for flexible GHLC elements of disclosure 2 or 3, wherein the curable resin comprises a monofunctional (meth)acrylic acid compound having a cyclic ether structure.

[0014] This disclosure 5 is a sealant for flexible GHLC elements according to disclosures 1, 2, 3 or 4, wherein the curable resin contains a polyfunctional (meth)acrylic acid compound having two or more (meth)acryloyl groups in one molecule, and the content of the polyfunctional (meth)acrylic acid compound in 100 parts by mass of the curable resin is 0.1 parts by mass or more and 50 parts by mass or less.

[0015] This disclosure 6 is a sealant for flexible GHLC elements of disclosures 1, 2, 3, 4 or 5, which also contains a thermoplastic resin.

[0016] This disclosure 7 is a sealant for flexible GHLC elements according to disclosures 1, 2, 3, 4, 5 or 6, wherein the molecular weight between the crosslinking points of the cured product is 100 g / mol or more and 20,000 g / mol or less.

[0017] This disclosure 8 is a sealant for flexible GHLC elements according to disclosures 1, 2, 3, 4, 5, 6 or 7, wherein the viscosity measured using an E-type viscometer at 25°C and 1 rpm is 1 Pa·s or higher.

[0018] The present invention will be described in detail below.

[0019] The inventors conducted research on sealants for flexible GHLC elements as follows: by setting the glass transition temperature of the cured material below a specific temperature and the storage modulus at 25°C below a specific value, the adhesion immediately after light irradiation was improved. Furthermore, by ensuring that the storage modulus at 80°C does not significantly decrease compared to the storage modulus at 25°C, adhesion was maintained even under high-temperature conditions. The results showed that a sealant for flexible GHLC elements exhibiting excellent adhesion to films with oriented films, even immediately after light irradiation and under high-temperature conditions, was obtained, thus completing this invention.

[0020] The upper limit of the glass transition temperature of the cured product of the sealant for flexible GHLC elements of the present invention is 60°C. By setting the glass transition temperature of the cured product to 60°C or below and the storage modulus at 25°C (described later) to 500 MPa or below, the sealant for flexible GHLC elements of the present invention exhibits excellent adhesion to films with oriented films even immediately after light irradiation. The preferred upper limit of the glass transition temperature of the cured product is 50°C, and more preferably 40°C.

[0021] Furthermore, there is no particular limitation on the preferred lower limit of the glass transition temperature of the above-mentioned cured material; the practical lower limit is -70°C.

[0022] It should be noted that the glass transition temperature of the cured material described above in this specification can be obtained as follows: for a cured material with a thickness of 300 μm, the temperature at which the loss tangent (tanδ) reaches its maximum value is obtained when measuring dynamic viscoelasticity using a dynamic viscoelasticity measuring device under the following conditions: test piece width 5 mm, holding width 25 mm, heating rate 10 °C / min, temperature range -80 °C to 200 °C, and frequency 10 Hz. For example, a DVA-200 (manufactured by IT Measurement & Control Co., Ltd.) can be used as the aforementioned dynamic viscoelasticity measuring device.

[0023] Furthermore, the cured material used to determine the glass transition temperature and storage modulus described below can be obtained by light irradiation alone, or by light irradiation and heating, depending on the curing type of the sealant for flexible GHLC elements described above. As a specific curing method, in the case of a light-curing sealant, an irradiation wavelength of 365 nm and an illuminance of 100 mW / cm² are used. 2 Methods such as irradiation for 30 seconds, using a wavelength of 365nm and an illuminance of 100mW / cm² in the case of photothermal curing sealants. 2 Methods such as irradiating light for 30 seconds and then heating at 80°C for 60 minutes.

[0024] The cured product of the flexible GHLC element sealant of the present invention has a storage modulus of up to 500 MPa at 25°C. By ensuring that the storage modulus of the cured product at 25°C is 500 MPa or less and the glass transition temperature of the cured product is 60°C or less, the flexible GHLC element sealant of the present invention exhibits excellent adhesion to films with oriented films even immediately after light irradiation. The preferred upper limit of the storage modulus of the cured product at 25°C is 100 MPa, and a more preferred upper limit is 50 MPa.

[0025] Furthermore, from the viewpoint of moisture permeability prevention, the preferred lower limit of the storage modulus of the above-mentioned solidified material at 25°C is 0.01 MPa, and the more preferred lower limit is 0.05 MPa.

[0026] It should be noted that the storage modulus of the cured material at 25°C and the storage modulus of the cured material at 80°C (described later) can be determined by dynamic viscoelasticity measurement of a 300 μm thick cured material, using the same method as measuring the glass transition temperature of the cured material.

[0027] The cured product of the sealant for flexible GHLC elements of the present invention has a lower limit of 0.01 MPa in storage modulus at 80°C. By ensuring that the storage modulus of the cured product at 80°C is 0.01 MPa or higher, the sealant for flexible GHLC elements of the present invention can maintain adhesion to films with oriented films even under high temperature conditions. The preferred lower limit of the storage modulus of the cured product at 80°C is 0.02 MPa, and a more preferred lower limit is 0.04 MPa.

[0028] In addition, the energy storage modulus of the above-mentioned cured material at 80°C is preferably small compared with the energy storage modulus of the above-mentioned cured material at 25°C. There is no particularly preferred upper limit, but the practical upper limit is 500 MPa.

[0029] In the sealant for flexible GHLC elements of the present invention, the preferred lower limit of the molecular weight between the crosslinking points of the cured material is 100 g / mol, and the preferred upper limit is 20,000 g / mol. By setting the molecular weight between the crosslinking points of the cured material within this range, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferred lower limit of the molecular weight between the crosslinking points of the cured material is 500 g / mol, and a more preferred upper limit is 1000 g / mol.

[0030] It should be noted that, regarding the molecular weight between the aforementioned crosslinking points, in the determination of the storage modulus of the cured product, the temperature at which the storage modulus becomes minimal above the glass transition temperature is defined as T (K), the storage modulus at temperature T is defined as E' (Pa), and the density of the cured product is defined as ρ (g / m³). 3 When the gas constant is set to R (J / (mol·K)), it can be obtained using the following formula.

[0031] Molecular weight between cross-linking points = 3ρRT / E'

[0032] The sealant for flexible GHLC elements of the present invention contains a curable resin.

[0033] The curable resin described above preferably contains (meth)acrylic acid compounds. In sealants for liquid crystal elements, liquid crystal contamination sometimes occurs due to the sealant coming into contact with the liquid crystal before curing. However, by using the aforementioned (meth)acrylic acid compounds as the curable resin, the resulting sealant for flexible GHLC elements exhibits excellent low liquid crystal contamination properties.

[0034] It should be noted that in this specification, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid, "(meth)acrylic acid compounds" refers to compounds having a (meth)acryloyl group, and "(meth)acryloyl group" refers to an acryloyl group or a methacryloyl group.

[0035] The aforementioned (meth)acrylic acid compounds preferably include monofunctional (meth)acrylic acid compounds having one (meth)acryloyl group in one molecule. By containing the aforementioned monofunctional (meth)acrylic acid compounds, the resulting sealant for flexible GHLC elements exhibits excellent wettability to films with oriented films, thereby providing superior adhesion to films with oriented films.

[0036] Preferably, the curable resin comprises a monofunctional (meth)acrylic acid compound with a glass transition temperature of 20°C or lower than that of a homopolymer. Using a monofunctional (meth)acrylic acid compound containing a homopolymer with a glass transition temperature of 20°C or lower, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. The glass transition temperature of the homopolymer is preferably 10°C or lower.

[0037] Furthermore, there is no particular limitation on the preferred lower limit of the glass transition temperature of the above homopolymers; the practical lower limit is -70°C.

[0038] It should be noted that the above-mentioned "glass transition temperature of homopolymer" refers to the existence of homopolymers exhibiting the defined glass transition temperature within the range of weight-average molecular weight of 10,000 or more and 100,000 or less.

[0039] Furthermore, in this specification, the aforementioned "weight-average molecular weight" is a value determined by gel permeation chromatography (GPC) and converted from polystyrene. Examples of columns used for determining the weight-average molecular weight by GPC based on polystyrene conversion include the Shodex LF-804 (manufactured by Showa Denko Corporation).

[0040] Monofunctional (meth)acrylic acid compounds with a glass transition temperature of less than 20°C, such as butyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and (2-methyl-2-ethyl-1,3-dioxane-4-yl)methyl (meth)acrylate, are examples of the above-mentioned homopolymers.

[0041] It should be noted that in this specification, "(meth)acrylate" refers to acrylate or methacrylate.

[0042] Furthermore, from the viewpoint of further improving the wettability of the sealant for the obtained flexible GHLC element to the film with the oriented film, the above-mentioned curable resin preferably contains a monofunctional (meth)acrylic acid compound having a cyclic ether structure as the above-mentioned monofunctional (meth)acrylic acid compound.

[0043] Examples of cyclic ether structures include ethylene oxide rings, oxetane rings, dioxetane rings, tetrahydrofuran rings, and furan rings. Among these, dioxetane rings are preferred.

[0044] Examples of monofunctional (meth)acrylic acid compounds with cyclic ether structures include (meth)acrylic acid (2-methyl-2-ethyl-1,3-dioxacyclopentan-4-yl) methyl ester and (3,4-epoxycyclohexyl) methyl ester.

[0045] The aforementioned curable resin may include other monofunctional (meth)acrylic compounds whose glass transition temperature exceeds 20°C and which do not have a cyclic ether structure as the aforementioned monofunctional (meth)acrylic compounds.

[0046] As for the other monofunctional (meth)acrylic acid compounds mentioned above, monofunctional (meth)acrylimide compounds are suitable.

[0047] Examples of monofunctional (meth)acrylimide compounds include N-(meth)acryloxyethylhexahydrophthalimide.

[0048] The preferred lower limit for the content of the aforementioned monofunctional (meth)acrylic acid compound in 100 parts by weight of the aforementioned curable resin is 50 parts by weight. By ensuring that the content of the aforementioned monofunctional (meth)acrylic acid compound is 50 parts by weight or more, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferred lower limit for the content of the aforementioned monofunctional (meth)acrylic acid compound is 70 parts by weight.

[0049] Furthermore, from the viewpoint of curability, the preferred upper limit of the content of the above-mentioned monofunctional (meth)acrylic acid compound in 100 parts by weight of the above-mentioned curable resin is 99.9 parts by weight.

[0050] The curable resin described above preferably comprises a polyfunctional (meth)acrylic acid compound having two or more (meth)acryloyl groups in one molecule. By containing the aforementioned polyfunctional (meth)acrylic acid compound, the resulting sealant for flexible GHLC elements exhibits excellent curability and superior adhesion to films with oriented films under high-temperature conditions.

[0051] Examples of the aforementioned multifunctional (meth)acrylate compounds include those belonging to the categories of epoxy (meth)acrylates, (meth)acrylate compounds, and urethane (meth)acrylates, which have two or more (meth)acryloyl groups in one molecule. Preferably, the curable resin comprises the aforementioned epoxy (meth)acrylate.

[0052] It should be noted that, in this specification, "epoxy (meth)acrylate" refers to a compound formed by reacting all the epoxy groups in an epoxy compound with (meth)acrylic acid.

[0053] Examples of the aforementioned epoxy (meth)acrylates include substances obtained by reacting an epoxy compound having two or more epoxy groups in one molecule with (meth)acrylic acid in the presence of a basic catalyst using conventional methods.

[0054] Examples of epoxy compounds that can serve as raw materials for the aforementioned epoxy (meth)acrylates include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol E type epoxy compounds, bisphenol S type epoxy compounds, 2,2'-diallyl bisphenol A type epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide addition bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, thioether type epoxy compounds, diphenyl ether type epoxy compounds, dicyclopentadiene type epoxy compounds, naphthyl type epoxy compounds, phenolic varnish type epoxy compounds, o-cresol phenolic varnish type epoxy compounds, dicyclopentadiene phenolic varnish type epoxy compounds, biphenyl phenolic varnish type epoxy compounds, naphthol phenolic varnish type epoxy compounds, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber modified type epoxy compounds, and glycidyl ester compounds.

[0055] Examples of difunctional compounds among the aforementioned (meth)acrylate compounds include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and poly(meth)acrylate. Propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide addition bisphenol A di(meth)acrylate, propylene oxide addition bisphenol A di(meth)acrylate, ethylene oxide addition bisphenol F di(meth)acrylate, dihydroxymethyldicyclopentadienyl di(meth)acrylate, ethylene oxide modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate glycol di(meth)acrylate, polyether glycol di(meth)acrylate, polyester glycol di(meth)acrylate, polycaprolactone glycol di(meth)acrylate, polybutadiene glycol di(meth)acrylate, etc.

[0056] Examples of compounds with three or more functions among the aforementioned (meth)acrylate compounds include ethylene oxide addition tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide addition trimethylolpropane tri(meth)acrylate, propylene oxide addition trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, propylene oxide addition glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tri(meth)acryloyloxyethyl phosphate, bis(trimethylolpropane)tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0057] The aforementioned urethane (meth)acrylates can be obtained, for example, by reacting an isocyanate compound with a (meth)acrylate derivative having a hydroxyl group in the presence of a catalytic amount of a tin-based compound.

[0058] Examples of isocyanate compounds that can serve as raw materials for the aforementioned urethane (meth)acrylates include isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), hydrogenated MDI, polymerized MDI, 1,5-naphthalene diisocyanate, norbornene diisocyanate, bitoluidine diisocyanate, phenylmethylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tri(isocyanate phenyl)thiophosphate, tetramethylphenylmethylene diisocyanate, and 1,6,11-undecane triisocyanate.

[0059] Alternatively, the isocyanate compound used as a raw material for the aforementioned urethane (meth)acrylate can be a chain-extended isocyanate compound obtained by reacting a polyol with an excess of the isocyanate compound.

[0060] Examples of the aforementioned polyols include ethylene glycol, propylene glycol, glycerin, sorbitol, trimethylolpropane, carbonate glycol, polyether glycol, polyester glycol, and polycaprolactone glycol.

[0061] Examples of the above-mentioned (meth)acrylic acid derivatives having hydroxyl groups include hydroxyalkyl (meth)acrylic acid esters, mono(meth)acrylic acid esters of diols, mono(meth)acrylic acid esters or di(meth)acrylic acid esters of triols, epoxy (meth)acrylic acid esters, etc.

[0062] Examples of hydroxyalkyl esters of (meth)acrylate include 2-hydroxyethyl ester, 2-hydroxypropyl ester, 2-hydroxybutyl ester, and 4-hydroxybutyl ester.

[0063] Examples of the aforementioned diols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol.

[0064] Examples of the aforementioned triols include trimethylolethane, trimethylolpropane, and glycerol.

[0065] Examples of the aforementioned epoxy (meth)acrylates include, for example, bisphenol A type epoxy (meth)acrylates.

[0066] From the viewpoint of further improving the adhesion of the sealant for the obtained flexible GHLC element to the film with the oriented film, the above-mentioned multifunctional (meth)acrylic acid compound preferably has a soft skeleton.

[0067] Examples of flexible backbones include open-ring structures of lactones, polyepoxide structures, rubber structures derived from conjugated dienes, and polysiloxane structures. Among these, open-ring structures of lactones are preferred.

[0068] Examples of the aforementioned lactones include γ-undecyl lactone, ε-caprolactone, γ-decyl lactone, σ-dodecyl lactone, γ-nonyl lactone, γ-heptyl lactone, γ-valeryl lactone, σ-valeryl lactone, β-butyl lactone, γ-butyl lactone, β-propiolactone, σ-caprolactone, and ε-decyl lactone (7-butyl-2-oxepanone).

[0069] The preferred lower limit for the content of the aforementioned polyfunctional (meth)acrylic acid compound in 100 parts by weight of the aforementioned curable resin is 0.1 parts by weight, and the preferred upper limit is 50 parts by weight. By setting the content of the aforementioned polyfunctional (meth)acrylic acid compound within this range, the resulting sealant for flexible GHLC elements exhibits superior curability, adhesion to films with oriented films, and low liquid crystal contamination. A more preferred lower limit for the content of the aforementioned polyfunctional (meth)acrylic acid compound is 0.5 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0070] The preferred lower limit for the content of the aforementioned (meth)acrylic acid compound in 100 parts by weight of the aforementioned curable resin is 55 parts by weight. By ensuring that the content of the aforementioned (meth)acrylic acid compound is 55 parts by weight or more, the resulting sealant for flexible GHLC elements exhibits superior adhesion under high-temperature conditions. A more preferred lower limit for the content of the aforementioned (meth)acrylic acid compound is 60 parts by weight. The content of the aforementioned (meth)acrylic acid compound in 100 parts by weight of the aforementioned curable resin is particularly preferably 100 parts by weight, i.e., the aforementioned curable resin is composed solely of the aforementioned (meth)acrylic acid compound.

[0071] The preferred lower limit of the content of the curable resin in 100 parts by weight of the sealant for flexible GHLC elements of the present invention is 90 parts by weight, and the preferred upper limit is 99 parts by weight. By setting the content of the curable resin within this range, the sealant for flexible GHLC elements obtained has better curability and adhesion.

[0072] The sealant for flexible GHLC elements of the present invention contains a photopolymerization initiator.

[0073] As the aforementioned photopolymerization initiator, a photoradical polymerization initiator is preferably used.

[0074] Examples of photoradical polymerization initiators include benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanoceramsite compounds, oxime ester compounds, benzoin ether compounds, and thioxanone compounds.

[0075] Specifically, examples of photoradical polymerization initiators include 1-hydroxycyclohexylphenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholino)phenyl)-1-butanone, 2,2-dimethoxy-1,2-diphenylethane-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-methyl-1-(4-methyl)phenylphenyl)-1-butanone. Thiophenyl)-2-morpholinopropane-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propane-1-one, 1-(4-(phenylthio)phenyl)-1,2-octanedione, 2-(O-benzoyl oxime), 2-(acetoxyimino)-1-(4-(4-(2-hydroxyethoxy)phenylthio)phenyl)propane-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,4-dimethylthioxanthion-9-one, etc.

[0076] The preferred lower limit of the content of the photopolymerization initiator relative to 100 parts by weight of the curable resin is 0.01 parts by weight, and the preferred upper limit is 10 parts by weight. By keeping the content of the photopolymerization initiator within this range, the resulting sealant for flexible GHLC elements exhibits superior storage stability and photocurability. A more preferred lower limit of the content of the photopolymerization initiator is 0.1 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0077] The sealant for flexible GHLC elements of the present invention may contain a thermal polymerization initiator to a extent that does not impair the purpose of the present invention.

[0078] Thermal free radical polymerization initiators are suitable as the aforementioned thermal polymerization initiators.

[0079] Examples of thermal free radical polymerization initiators include those composed of azo compounds and organic peroxides. From the viewpoint of suppressing pollution of dimming materials, initiators composed of azo compounds (hereinafter also referred to as "azo initiators") are preferred.

[0080] The above-mentioned thermal free radical polymerization initiators can be used alone or in combination of two or more.

[0081] Specifically, examples of the aforementioned azo compounds include azo compounds having a structure in which multiple polyepoxides, polydimethylsiloxanes, etc., are bonded by azo groups; condensation polymers of 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 4,4'-azobis(4-cyanovaleric acid) with polyalkylene glycols; and condensation polymers of 4,4'-azobis(4-cyanovaleric acid) with polydimethylsiloxane having terminal amino groups.

[0082] Examples of azo initiators mentioned above include VPE-0201, VPE-0401, VPE-0601, VPS-0501, VPS-1001, V-65, and V-501 (all manufactured by Fujifilm and Kojun Pharmaceutical Co., Ltd.).

[0083] Examples of the aforementioned organic peroxides include: peroxide ketones, peroxide ketals, hydrogen peroxide, dialkyl peroxides, peroxide esters, diacyl peroxides, and peroxydicarbonates.

[0084] The preferred lower limit of the content of the aforementioned thermal polymerization initiator relative to 100 parts by weight of the aforementioned curable resin is 0.01 parts by weight, and the preferred upper limit is 10 parts by weight. By setting the content of the aforementioned thermal polymerization initiator within this range, the resulting sealant for flexible GHLC elements exhibits superior storage stability and thermosetting properties. A more preferred lower limit of the content of the aforementioned thermal polymerization initiator is 0.1 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0085] From the viewpoint of adjusting the viscosity of the sealant for flexible GHLC elements and further improving the adhesion to films with oriented films, the sealant for flexible GHLC elements of the present invention preferably also contains a thermoplastic resin.

[0086] The glass transition temperature of the aforementioned thermoplastic resin is preferably 20°C or lower. By setting the glass transition temperature of the aforementioned thermoplastic resin to 20°C or lower, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferable upper limit for the glass transition temperature of the aforementioned thermoplastic resin is 15°C.

[0087] Furthermore, the preferred lower limit of the glass transition temperature of the aforementioned thermoplastic resin is not particularly limited, but the practical lower limit is -125°C.

[0088] It should be noted that, in this specification, the glass transition temperature of the thermoplastic resin mentioned above refers to the value measured by differential scanning calorimetry (DSC) based on JISK 7121.

[0089] The preferred lower limit for the weight-average molecular weight of the aforementioned thermoplastic resin is 10,000, and the preferred upper limit is 1,000,000. By setting the weight-average molecular weight of the aforementioned thermoplastic resin within this range, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferred lower limit for the weight-average molecular weight of the aforementioned thermoplastic resin is 50,000, and a more preferred upper limit is 500,000.

[0090] Examples of the aforementioned thermoplastic resins include styrene / (meth)acrylic acid copolymers, (meth)acrylic acid copolymers, polyolefins, polyesters, polyamides, polyurethanes, polystyrene, polycarbonates, polyphenylene ethers, ABS resins, AES resins, AAS resins, MBS resins, and phenoxy resins. Among these, the aforementioned (meth)acrylic acid / styrene copolymers are preferred as the aforementioned thermoplastic resins.

[0091] Furthermore, the aforementioned thermoplastic resin is preferably a block copolymer.

[0092] The preferred lower limit of the content of the aforementioned thermoplastic resin relative to 100 parts by weight of the aforementioned curable resin is 10 parts by weight, and the preferred upper limit is 50 parts by weight. By keeping the content of the aforementioned thermoplastic resin within this range, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferred lower limit of the content of the aforementioned thermoplastic resin is 20 parts by weight, and a more preferred upper limit is 40 parts by weight.

[0093] The sealant for flexible GHLC elements of the present invention may also contain additives such as thermosetting agents, curing accelerators, light-blocking agents, fillers, silane coupling agents, stress relievers, reactive diluents, thixotropic agents, spacers, defoamers, leveling agents, and polymerization inhibitors as needed.

[0094] As a method for manufacturing the sealant for the flexible GHLC element of the present invention, examples include a method of mixing a curable resin, a photopolymerization initiator, a thermoplastic resin to be used as needed, and additives using a mixer.

[0095] Examples of such mixers include homogenizers, homogenizing mixers, universal mixers, planetary mixers, kneaders, and three-roll mills.

[0096] The preferred lower limit of the viscosity of the sealant for flexible GHLC elements of the present invention, measured using an E-type viscometer at 25°C and 1 rpm, is 1 Pa·s. By achieving a viscosity of 1 Pa·s or higher, the resulting sealant for flexible GHLC elements exhibits superior adhesion to films with oriented films. A more preferred lower limit of the above viscosity is 10 Pa·s.

[0097] Furthermore, from the viewpoint of coatability, the preferred upper limit of the above viscosity is 500 Pa·s, and the more preferred upper limit is 400 Pa·s.

[0098] For example, the DV-III (manufactured by BROOK FIELD) can be used as the above-mentioned E-type viscometer.

[0099] The sealant for flexible GHLC elements of the present invention can be suitably used in the manufacture of GHLC elements based on liquid crystal dispensing.

[0100] Examples of methods for manufacturing GHLC elements by liquid crystal droplet injection include the following.

[0101] First, a step is performed to form a frame-shaped sealing pattern by applying the flexible GHLC element sealant of the present invention onto a thin-film substrate using methods such as screen printing or a distributor. Next, a step is performed where, while the flexible GHLC element sealant of the present invention is not cured, tiny droplets of host and guest liquid crystals are applied to the entire surface within the frame of the sealing pattern, and other thin-film substrates are immediately overlapped. Then, a step is performed to cure the sealant by irradiating the sealing pattern with ultraviolet light or the like. This method allows the production of a GHLC element. Alternatively, a step of heating the sealant to cure it can be performed after the step of curing the sealant by irradiating the sealing pattern with ultraviolet light or the like.

[0102] Furthermore, the sealant for flexible GHLC elements of the present invention is preferably used for sealing GHLC dimming elements having a thin film substrate.

[0103] The effects of the invention

[0104] According to the present invention, a sealant for flexible GHLC elements can be provided that exhibits excellent adhesion to films with oriented films, even immediately after irradiation and under high temperature conditions. Detailed Implementation

[0105] The present invention is illustrated in more detail by the following examples, but the present invention is not limited to these examples.

[0106] (Examples 1-12, Comparative Examples 1-5)

[0107] Following the mixing ratios described in Tables 1 and 2, each material was stirred using a planetary mixer and then uniformly mixed using a ceramic three-roller to obtain the sealants for flexible GHLC elements in Examples 1-12 and Comparative Examples 1-5. The planetary mixer used was Awatori Rentaro (manufactured by THINKY Corporation).

[0108] (Viscosity)

[0109] The viscosity of the sealant used for the obtained flexible GHLC elements was measured using an E-type viscometer (BROOK FIELD, "DV-III") at 25°C and 1 rpm. The results are shown in Tables 1 and 2.

[0110] (Glass transition temperature, storage modulus, and molecular weight between crosslinking points of the cured product)

[0111] For the sealants used in the flexible GHLC elements obtained in Examples 1-12 and Comparative Examples 1-4, a metal halide lamp was used to irradiate the components with a wavelength of 365 nm and an illuminance of 100 mW / cm². 2 The curing agent was subjected to 30 seconds of light to obtain a 300 μm thick cured material. Additionally, the sealant for the flexible GHLC element obtained in Comparative Example 5 was tested by irradiation with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm². 2 After 30 seconds of exposure to light, the sample was heated at 80°C for 60 minutes to obtain a cured material with a thickness of 300 μm. The aforementioned metal halide lamp used was an MB1500T-3 (manufactured by SEN Special Light Source Co., Ltd.).

[0112] For the obtained cured material, dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring device (IT Measurement & Control Co., Ltd., "DVA-200") under the following conditions: test piece width 5 mm, holding width 25 mm, heating rate 10 °C / min, temperature range -80 °C to 200 °C, and frequency 10 Hz. The glass transition temperature, storage modulus at 25 °C and 80 °C, and molecular weight between crosslinking points were determined. The results are shown in Tables 1 and 2.

[0113] <Evaluation>

[0114] The obtained flexible GHLC elements were evaluated using sealants as follows. The results are shown in Tables 1 and 2.

[0115] (Adhesion to films with oriented films)

[0116] (1) Immediately after irradiation

[0117] An imide resin was spin-coated onto a PET film with an ITO film, pre-baked at 80°C, and then fired at 230°C to produce a PET film with an alignment film (25 mm in length and 45 mm in width). SE7492 (manufactured by Nichiban Chemicals Co., Ltd.) was used as the imide resin. Furthermore, all PET films with alignment films used below were pre-bonded to a glass substrate (25 mm in length and 45 mm in width) using adhesive tape (manufactured by Nichiban Co., Ltd., "Nicetack") on the side of the PET film opposite to the alignment film.

[0118] A sealant for the resulting flexible GHLC element was micro-dropped onto one of two PET films with alignment films. The other PET film with alignment film was then laminated in a cross shape and irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm². 2 The light was applied for 30 seconds to obtain the test piece. The metal halide lamp used was an MB1500T-3 (manufactured by SEN Special Light Source Co., Ltd.).

[0119] For test pieces immediately after irradiation, a metal cylinder with a radius of 5 mm is pressed into the end of the PET film with the alignment film on the lower side at a speed of 5 mm / min. The strength of the PET film with the alignment film when peeling occurs is measured. The obtained value (kgf) is divided by the diameter of the joint (cm) to obtain the adhesive force. The adhesiveness is evaluated according to the following criteria.

[0120] ◎: For cases where the adhesive strength is 3.0 kgf / cm or higher.

[0121] ○: The adhesive strength is 1.5 kgf / cm or higher but less than 3.0 kgf / cm.

[0122] ×: Cases where the adhesive strength is less than 1.5 kgf / cm

[0123] (2) Under high temperature conditions

[0124] For the test pieces obtained in the same manner as those in "(1) immediately after irradiation", the adhesive strength was measured in the same manner as those in "(1) immediately after irradiation" while maintaining the temperature at 80°C, and the adhesiveness was evaluated according to the following criteria.

[0125] ◎: For cases where the adhesive strength is 2.0 kgf / cm or higher

[0126] ○: The adhesive strength is 1.0 kgf / cm or more but less than 2.0 kgf / cm.

[0127] ×: Cases where the adhesive strength is less than 1.0 kgf / cm

[0128] (Low liquid crystal pollution)

[0129] One part by mass of spacer particles (Micropearl SI-H050, manufactured by Sekisui Chemicals Co., Ltd.) with an average particle size of 7 μm was dispersed in 100 parts by mass of the obtained flexible GHLC element sealant. This mixture was then filled into a syringe and degassed using a centrifugal degassing machine (AWATORON AW-1, manufactured by Musashi Engineering, Inc.). Using a dispenser, the degassed flexible GHLC element sealant was applied to one of two oriented PET films obtained in the same manner as described above (adhesion to films with oriented films), forming a frame-shaped sealing pattern. At this time, the discharge pressure was adjusted so that the linewidth of the flexible GHLC element sealant was approximately 1.0 mm. Next, tiny droplets of liquid crystal (4-pentyl-4-biphenylnitrile, manufactured by Tokyo Chemical Industry Co., Ltd.) were applied to the entire surface of the sealing pattern within the frame of the oriented PET film coated with the flexible GHLC element sealant, and the other oriented PET film was bonded under vacuum. After the vacuum was released, the flexible GHLC element with the sealing pattern was cured with the sealant using the following method to obtain a test piece. For the sealants used in Examples 1-12 and Comparative Examples 1-4, the flexible GHLC element sealants were irradiated with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm². 2 The sealant for the flexible GHLC element obtained in Comparative Example 5 was cured by irradiation with a metal halide lamp at a wavelength of 365 nm and an illuminance of 100 mW / cm². 2 After 30 seconds of exposure to light, the lamp is heated at 80°C for 60 minutes to cure it. The aforementioned metal halide lamp used was an MB1500T-3 (manufactured by SEN Special Light Source Co., Ltd.).

[0130] For the obtained test pieces, orientation disorder was confirmed by observing the liquid crystal portion for color inhomogeneity using a polarizing microscope (KEYENCE, "VHX-5000"). Low liquid crystal contamination was evaluated according to the following criteria.

[0131] ◎: No evidence of orientation disorder has been confirmed.

[0132] ○: Orientation disorder was only detected near the seal pattern (peripheral area).

[0133] ×: Orientation disorder extending to the central part

[0134] [Table 1]

[0135]

[0136] [Table 2]

[0137]

[0138] Industrial availability

[0139] According to the present invention, a sealant for flexible GHLC elements can be provided that exhibits excellent adhesion to films with oriented films, even immediately after irradiation and under high temperature conditions.

Claims

1. A sealant for a flexible GHLC element, characterized by, It contains curable resin and photopolymerization initiator. The glass transition temperature of the cured sealant for the flexible GHLC element is below 60°C, the storage modulus of the cured material at 25°C is below 500 MPa, and the storage modulus of the cured material at 80°C is above 0.01 MPa.

2. The sealant for flexible GHLC elements according to claim 1, wherein, The curable resin comprises a monofunctional (meth)acrylic acid compound having one (meth)acryloyl group in one molecule. The content of the monofunctional (meth)acrylic acid compound in 100 parts by weight of the curable resin is more than 50 parts by weight.

3. The sealant for flexible GHLC elements according to claim 2, wherein, The curable resin comprises a monofunctional (meth)acrylic acid compound whose glass transition temperature is below 20°C.

4. The sealant for flexible GHLC elements according to claim 2 or 3, wherein, The curable resin comprises a monofunctional (meth)acrylic acid compound having a cyclic ether structure.

5. The sealant for flexible GHLC elements according to claim 1, 2, 3 or 4, wherein, The curable resin comprises a polyfunctional (meth)acrylic acid compound having two or more (meth)acryloyl groups in one molecule. The content of the polyfunctional (meth)acrylic acid compound in 100 parts by weight of the curable resin is more than 0.1 parts by weight and less than 50 parts by weight.

6. The sealant for flexible GHLC elements according to claim 1, 2, 3, 4 or 5, further comprising a thermoplastic resin.

7. The sealant for flexible GHLC elements according to claim 1, 2, 3, 4, 5 or 6, wherein the molecular weight between the crosslinking points of the cured product is 100 g / mol or more and 20,000 g / mol or less.

8. The sealant for flexible GHLC elements according to claim 1, 2, 3, 4, 5, 6 or 7, wherein, Using an E-type viscometer, the viscosity measured at 25°C and 1 rpm was greater than 1 Pa·s.

Images