JPH06167700A - Method of manufacturing light control sheet - Google Patents

Abstract

(57) [Summary] [Object] The present invention is a method for manufacturing a light control sheet using an electron beam for curing a resin, wherein unnecessary impurities are generated due to decomposition reaction of liquid crystal by electron beam energy, and the light control sheet. It is intended to provide a method for solving the problem of deterioration in quality as described above, and manufacturing a high-quality light control sheet industrially continuously at low cost and efficiently. According to the present invention, an electrode layer of a transparent film having an electrode layer is coated with a coating liquid containing an electron beam curing resin and a liquid crystal substance as main components, and another transparent layer having an electrode layer is formed on the coating layer. To accelerate the curing of the resin and the phase separation of the liquid crystal by irradiating the film with an electron beam over a number of times while the electrode layer surfaces of the film are adhered and both surfaces are in close contact with each other. Is characterized by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, when used for windows and the like,
The present invention relates to a method for manufacturing a light control sheet capable of adjusting light transmission.

[0002]

2. Description of the Related Art In recent years, a light control sheet made of polymer-dispersed liquid crystal utilizing the anisotropy of refractive index of liquid crystal has been proposed. As shown in FIG. 1, this light control sheet disperses liquid crystal droplets in a polymer matrix, film-forming the polymer, and changing the orientation degree of the liquid crystal depending on the presence or absence of an electric field. It is based on the principle of adjusting and controlling the transmission and scattering states of light.

A light control sheet based on this principle is of a type in which a liquid crystal is impregnated in a porous film (Appl.Phys.Le
TT.40 (1) 22 (1982) developed by H, C, Craighead et al.), a type in which liquid crystal is microencapsulated using polyvinyl alcohol (Japanese Patent Publication No. 58-501631), and the liquid crystal is made of epoxy resin. A type in which the liquid crystal is dissolved in an organic solvent solution and the liquid crystal is phase-separated by evaporating the solvent (Japanese Patent Publication Sho 61-50212).
8), a type in which the liquid crystal is dissolved in an organic solvent solution of polymethylmethacrylate and the solvent is evaporated to cause phase separation of the liquid crystal (Japanese Patent Laid-Open No. 63-43993), and the liquid crystal is dissolved in an ultraviolet curable resin. The resin is cured by ultraviolet irradiation and the liquid crystal is phase-separated (Japanese Patent Laid-Open No. 1-3125).
27) etc. are known.

However, all of these polymer-dispersed liquid crystal light-control sheets apply a coating liquid on a substrate with a bar coater to evaporate the solvent, or liquid crystal in a glass cell with a transparent electrode. This is a very inefficient production method, which is completely unsuitable for actual production in which a resin mixed liquid is injected and the resin is cured by irradiating heat or ultraviolet rays for a long time to produce a polymer dispersed liquid crystal.

Therefore, there is a method of using an electron beam to cure the resin instead of irradiating it with heat or ultraviolet rays. When irradiated with an electron beam, the resin cures efficiently, but
Since the reaction is abrupt, the phase separation becomes insufficient, and further, the decomposition reaction of the liquid crystal by the electron beam energy causes unnecessary impurities, which rather deteriorates the quality of the light control sheet. Has not solved practical problems.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the method for producing a light control sheet using an electron beam for curing a resin, and is a light control comprising a high quality polymer-dispersed liquid crystal. It is an object to provide a method for industrially, continuously, inexpensively and efficiently producing a sheet.

[0007]

According to the present invention, a coating liquid containing an electron beam curing resin and a liquid crystal substance as a main component is applied onto an electrode layer of a transparent film having an electrode layer, and an electrode is applied onto the applied layer. The electrode layer surface of another transparent film having a layer is adhered, and in the state where both surfaces are adhered to each other, the electron beam is radiated over the film over a number of times to cure the resin and phase-separate the liquid crystal. A method for manufacturing a light control sheet, which is characterized by accelerating stepwise.

[0008]

[Action] In the configuration of the present invention, the transparent film having an electrode layer, polyester, polycarbonate, polyimide, polyether sulfone, at 30~200μm thickness such as polymethyl methacrylate, the surface In ₂ O _3: S
A metal oxide such as nO _{2 is} fixed by a vapor deposition method, a sputtering method or the like to give conductivity.

Examples of the electron beam curable resin include the following prepolymers and monomers. (A) Aliphatic, alicyclic, araliphatic polyhydric alcohol of dihydric to hexahydric alcohol and poly (meth) acrylate of polyalkylene glycol (b) aliphatic, alicyclic, araliphatic, aromatic 2 to 6 Poly (meth) acrylate of polyhydric alcohol obtained by adding alkylene oxide to polyhydric polyhydric alcohol (c) Poly (meth) acryloyloxyalkyl phosphate (d) Polyester poly (meth) acrylate (e) Epoxy poly (Meth) acrylate (f) Polyurethane poly (meth) acrylate (g) Polyamide poly (meth) acrylate (h) Polysiloxane poly (meth) acrylate (i) Having (meth) acryloyloxy groups on side chains and / or terminals Vinyl- or diene-based low polymer (j) The oligoester (meta) described in (a) to (i) above. Prepolymers such as acrylate-modified product

The monomer includes (a) a carboxyl group-containing monomer represented by ethylenically unsaturated mono- or polycarboxylic acid and / or a carboxylate group-containing alkali metal salt, ammonium salt, amine salt or the like. Monomer (b) Ethylenically unsaturated (meth) acrylamide or alkyl-substituted (meth) acrylamide, amide group-containing monomer represented by vinyllactams such as N-vinylpyrrolidone (c) Aliphatic or aromatic Sulfonic acid group-containing monomers typified by vinyl sulfonic acids and sulfonic acid group-containing monomers such as alkali metal salts, ammonium salts, amine salts thereof (d) Hydroxyl group-containing monomers typified by ethylenically unsaturated ale Monomer (e) Dimethylaminoethyl (meth) acrylate-2
-Amino group-containing monomer such as vinyl pyridine (f) Quaternary ammonium salt group-containing monomer (g) Alkyl ester of ethylenically unsaturated carboxylic acid (h) Nitrile group-containing monomer such as (meth) acrylonitrile (I) Styrene (j) Esters of ethylenically unsaturated alcohols such as vinyl acetate and (meth) allyl acetate (k) Mono- (meth) acrylates of alkylene oxide addition polymers of compounds containing active hydrogen (l) Poly Ester group-containing bifunctional monomer represented by diester of basic acid and unsaturated alcohol (m) Bifunctional monofunctional monomer composed of diester of alkylene oxide addition polymer of compound containing active hydrogen and (meth) acrylic acid Polymer (n) Bisacrylamide such as N, N-methylenebisacrylamide (o) Divinylbenzene, divinylethylene Bifunctional monomer such as glycol, divinyl sulfone, divinyl ether, divinyl ketone (p) Ester group-containing polyfunctional monomer represented by polyester of polycarboxylic acid and unsaturated alcohol (q) Containing active hydrogen Polyfunctional monomer composed of polyester of alkylene oxide addition polymer of compound and (meth) acrylic acid (r) Polyfunctional unsaturated monomer composed of trivinylbenzene, and the like. One or two of them may be mentioned. At least one species may be used.

Examples of liquid crystal substances include Schiff chlorine-based, azo-based, azooxy-based, benzoic acid-based, cyanobienyl-based, cyanotabienyl-based, cyclohexylcarboxylic acid ester-based, phenylcyclohexane-based, biphenylcyclohexane-based, pyrimidine-based, dioxane-based, cyclohexyl-based. Cyclohexane ester type, cyclohexylethane type, cyclohexane type, tolan type, alkenyl type,
2,3-Difluorophenylene nematic or smectic liquid crystals are used alone or in combination of two or more.

It should be noted that, if necessary, a spacer, a surfactant, an antioxidant, an ultraviolet absorber, etc. may be added to the coating liquid comprising the electron beam curable resin and the liquid crystal substance to further enhance the effects of the invention. It is possible to raise it.

The mixing ratio of the electron beam curing resin and the liquid crystal substance is 1.8: 1.0 to 1.0: 4.0, preferably 1.5: by weight.
It is mixed between 1.0 and 1.0: 3.0. Incidentally, when the compounding ratio of the liquid crystal substance to the electron beam curing resin is 35% or less, the phase separation of the liquid crystal substance becomes insufficient. Further, if it exceeds 80%, the solubility in the resin is deteriorated and a high quality light control sheet cannot be obtained.

Thus, in order to obtain a high quality light control sheet,
When preparing the coating liquid by mixing the electron beam curable resin and the liquid crystal substance, it is necessary to take care so that bubbles are not generated or mixed in the coating liquid. For that purpose, it is preferable to use a roll mill as a mixing means in adjusting the coating liquid.

As means for applying the above-mentioned coating liquid onto the transparent film having an electrode layer, a roll coater, a curtain coater, a die coater, an offset gravure coater or the like suitable for applying without generating or mixing air bubbles is used. It is preferably used. Incidentally, a bar coater or an air knife coater is not preferable as a coating means because bubbles are easily generated or mixed in the coating layer.

The coating amount is 5 to 5 in terms of the thickness of the coating layer after curing.
It is 0 μm, preferably 5 to 30 μm. By the way, 5μ
If it is less than m, the function as a light control sheet cannot be exerted. When it exceeds 50 μm, it is extremely uneconomical and it becomes difficult to uniformly apply and cure the liquid crystal, so that phase separation of the liquid crystal becomes non-uniform and a high quality light control sheet cannot be obtained.

Thus, the above-mentioned coating liquid is applied onto the electrode layer of the transparent film having the electrode layer, and the electrode layer surface of another transparent film having the electrode layer is adhered onto the applied layer, but the adhesion It is desirable to nip and pressurize from above and below to improve the property. The sheet in the state of being stuck and adhered is then irradiated with an electron beam from above the film. The present invention is characterized in that the electron beam is irradiated over a number of times over time to accelerate the curing of the resin and the phase separation of the liquid crystal in stages.

The total amount of electron beam irradiated is 5 to 500
kGy The range of about 10 to 300 kGy is desirable. Incidentally, if it is less than 5 kGy, the resin component cannot be sufficiently cured, and excessive electron beam irradiation exceeding 500 kGy causes decomposition of the liquid crystal, which causes deterioration in quality.

The first irradiation with the electron beam is carried out so that the surface of the coating layer after the irradiation is irradiated with such a degree that some stickiness remains. Then, the wound sheet is rewound and irradiated with an electron beam again to complete the phase separation of the liquid crystal and the curing of the resin.

The number of times of electron beam irradiation is not limited to two, and more times are repeated over time (for example, after 1 hour has elapsed) to apply energy little by little to suppress the generation of unnecessary decomposition products as much as possible. However, if the phase separation and the curing of the resin are performed, a high quality light control sheet can be obtained.

The irradiation method may be a scanning method, a curtain method, a broad beam method, or the like, and an accelerating voltage during irradiation is preferably 150 to 300 kV.

[0022]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 A polyethylene terephthalate (PET) film was coated with I
n ₂ O ₃ : SnO ₂ vapor-deposited transparent conductive film (surface resistance 300 ohm / □, manufactured by Teijin: product name “T-COA
(T B300-125 ") was set in an electron beam curing device (Energy Science Co., Ltd.) equipped with a curtain coater, and a coating liquid having the following composition was applied to a thickness of 10 μm.

(Composition of coating liquid) Phenol EO-modified acrylate 30% by weight (Toagosei Kagaku Kogyo Aronix M-102) Trifunctional polyester acrylate 10% by weight (Toagosei Kagaku Aronix M-8030) Cyanobiphenyl nematic liquid crystal 60% by weight (BDH E-9)

On the coating layer of the above coating liquid, the electrode layer surface of another transparent conductive film having the same In ₂ O ₃ : SnO ₂ vapor-deposited as described above was pasted, and pressed by a roll from above and below to adhere them. .

200 kV-10 kG is applied to this adhesion film.
It was irradiated with an electron beam of y and wound up. The adhesive film was pulled out from this winding and was irradiated with an electron beam of 200 kV-20 kGy and wound. Further, the adhesive film was pulled out from this winding and irradiated with an electron beam of 200 kV-20 kGy, and energy of 50 kGy was added in total to obtain a light control sheet.

The obtained light control sheet had a milky white color in a good scattering state when no voltage was applied. The light transmittance in this case was 1%. Subsequently, when the electro-optical characteristic (voltage-transmittance characteristic) was driven by a rectangular wave of 800 Hz, it showed a light transmittance of 80% at 4 V as shown in FIG. 2, which is excellent as a light control sheet. Was.

(Comparative Example 1) The same coating composition as in Example 1 was applied and adhered by the same method, and 200
Irradiation with kV-50 kGy was carried out at once. The obtained device was transparent as compared with the device of Example 1 in the state where no voltage was applied. When voltage-transmittance characteristics were obtained by the same method as in Example 1, the transmittance was 80% when 4 V was applied, but the transmittance was 35% even when no voltage was applied.

[0028]

EFFECTS OF THE INVENTION According to the present invention, by irradiating the electron beam several times over time, the curing of the resin and the phase separation of the liquid crystal can be promoted in stages, and the decomposition of the liquid crystal does not occur. Since phase separation occurs well, a light control sheet made of high quality polymer-dispersed liquid crystal can be industrially, continuously, inexpensively and efficiently manufactured.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a light control sheet, showing a light scattering state when a voltage is not applied and a light transmission state when a voltage is applied.

FIG. 2 is a light control sheet obtained in Example 1 and Comparative Example 1
3 is a graph showing the relationship between the applied voltage (V) and the light transmittance of the light control sheet obtained in (1).

Claims (1)

[Claims] 1. A transparent film having an electrode layer is coated with a coating liquid containing an electron beam curable resin and a liquid crystal substance as a main component, and another transparent film having an electrode layer is coated on the coating layer. After the electrode layer surfaces are adhered to each other and the both surfaces are brought into close contact with each other, the resin is irradiated with an electron beam over a number of times over time to accelerate curing of the resin and phase separation of the liquid crystal step by step. And a method of manufacturing a light control sheet.