JPH04349426A - Production of liquid crystal device - Google Patents

Abstract

PURPOSE:To produce the liquid crystal device of a large area having a light control layer which is excellent in the uniformity of film thicknesses, light control function and adhesion to both-side substrates. CONSTITUTION:This process for producing the liquid crystal device having the light control layer constituted by forming a three-dimensional network structure consisting of a transparent high-polymer material in a continuous layer of a liquid crystal material consists of a stage for applying a light control layer constituting material contg. a liquid crystal material, a polymerizable compsn. and a photopolymn. initiator on a transparent substrate having an electrode layer, then precuring the polymerizable compsn. and a stage for sticking another substrate thereto, then completely curing the polymerizable compsn.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for manufacturing a liquid crystal device that can be manufactured over a large area.More specifically, the present invention relates to a method for manufacturing a liquid crystal device that can be manufactured over a large area. which can be thermally manipulated,
In addition to being used as visibility blocking screens and lighting control curtains in building windows and show windows, they can also be used as billboards, displaying text and figures, and switching the display electrically with high-speed response. The present invention relates to liquid crystal devices used as display devices such as guide boards and decorative display boards.

0002

2. Description of the Related Art Recently, demand for display devices using liquid crystals has been increasing in the display field.

Conventionally, liquid crystal devices of TN type and STN type using nematic liquid crystal have been put into practical use. Also, devices using ferroelectric liquid crystals have been proposed. These require a polarizing plate and also require alignment treatment.

On the other hand, as a method for producing a large, inexpensive liquid crystal device that is bright and has good contrast without requiring them, liquid crystal encapsulation is used to disperse liquid crystal droplets in a polymer, and then the polymer is made into a film. method is known. Here, gelatin, gum arabic, polyvinyl alcohol, etc. have been proposed as the encapsulating material (Japanese Patent Publication No. 58-501631, U.S. Patent No. 4
, No. 435,047).

[0005] In the technology disclosed in the above specification,
Liquid crystal molecules encapsulated in polyvinyl alcohol are
If it has positive dielectric constant anisotropy in a thin layer, its liquid crystal molecules will align in the direction of the electric field in the presence of an electric field,
When the refractive index no of the liquid crystal and the refractive index np of the polymer are equal, transparency is exhibited. When the electric field is removed, the liquid crystal molecules return to their random alignment, and the refractive index of the liquid crystal droplet deviates from the no. becomes cloudy.

On the other hand, instead of microencapsulating the liquid crystal material, by forming a three-dimensional network structure of a transparent polymer material in a continuous layer of the liquid crystal material, low voltage drive characteristics that cannot be achieved with the microencapsulation method can be achieved. It has been reported that it can be granted.

However, in this method of dispersing liquid crystal as a continuous layer, in order to obtain sufficient optical contrast, a large amount of liquid crystal must be contained in the light control layer, and there are restrictions on the substrates that can be used. Ta.

For example, even if it is possible to create a light control layer between glass substrates, if a flexible substrate such as a plastic film is used in place of the glass substrate, the microencapsulated light control layer In some cases, there was a problem in that the adhesion with the substrate was poor, which did not cause much of a problem, and a highly reliable liquid crystal device could not be manufactured.

Even when a glass substrate is used, the conventional method of injecting into a glass cell makes it possible to create a relatively small liquid crystal device, but as the size increases, uneven injection occurs. Due to these problems, there is a strong need for the development of a simple and highly productive method for manufacturing liquid crystal devices.

The problem to be solved by the present invention is to solve the problem of increasing the size of a liquid crystal device in a method for manufacturing a liquid crystal device having a light control layer formed by forming a three-dimensional network structure of a transparent polymer substance in a continuous layer of a liquid crystal material. An object of the present invention is to provide an easy method for manufacturing a liquid crystal device.

[0011]

[Means for Solving the Problems] As a result of extensive research, the present inventors have succeeded in solving the above problems.

That is, in order to solve the above problems, the present invention has the following objectives: 1. A light control layer constituting material containing a liquid crystal material, a polymerizable composition, and a photopolymerization initiator is interposed between two substrates having electrode layers, at least one of which is transparent, and the polymerizable composition is irradiated with ultraviolet rays. In a method for manufacturing a liquid crystal device having a light control layer formed by forming a three-dimensional network structure of a transparent polymer substance in a continuous layer of a liquid crystal material by polymerizing a composition, the light control layer structure is formed on one substrate. pre-curing the polymerizable composition after applying the material; and
2. A method for manufacturing a liquid crystal device, comprising the step of bonding another substrate onto the precured light control layer constituent material and then completely curing the polymerizable composition; and 2. The method for producing a liquid crystal device, wherein the amount of ultraviolet light used for preliminary curing is in the range of 5 to 70% of the amount of ultraviolet light necessary to completely cure the polymerizable composition. provide.

The substrate used in the present invention may be made of a rigid material, such as glass or metal, or may be made of a flexible material, such as a plastic film. Among these, it is particularly preferable to use a plastic film substrate, which allows the liquid crystal device to be easily enlarged.

[0014] Two substrates can be placed facing each other with an appropriate distance between them. Furthermore, at least one of the two must be transparent so that the light control layer sandwiched between the two can be seen from the outside world. However, complete transparency is not required. If this liquid crystal device is used to act on light passing from one side of the device to the other, the two substrates are
Both provide appropriate transparency. Appropriate transparent or opaque electrodes may be disposed on the entire surface or part of the substrate depending on the purpose.

However, in the case of flexible materials such as plastic films, rigid materials such as glass,
It can be used in the manufacturing method of the present invention after being fixed to metal or the like.

A light control layer made of a liquid crystal material and a transparent polymer material is interposed between the two substrates. Incidentally, a spacer for maintaining the distance between the two substrates can be interposed between the two substrates, similarly to a well-known liquid crystal device.

[0017] As the spacer, for example, mylar,
Various materials for liquid crystal cells such as alumina can be used, but rod-type glass fibers are preferred.

The light control layer of the liquid crystal device of the present invention is characterized by containing a liquid crystal as a continuous layer in a transparent polymeric substance. A polymer material obtained by polymerizing a polymerizable composition containing a compound represented by the following is suitable.

[0019]

[Chemical formula 1]

(In the formula, R1 represents a hydrogen atom or a methyl group, and R2 represents a halogen atom, a cyano group, an aliphatic group, or an aromatic group.)

This compound is a low-viscosity liquid polymerizable monomer, and can easily form a transparent polymeric substance by applying radiation such as ultraviolet rays or electron beams or polymerization energy such as heat. This polymerizable monomer has good compatibility with the liquid crystal material, and when mixed with the liquid crystal as a material for forming a light control layer, it can be prepared as a uniform solution.

As the polymerizable composition used for the material constituting the light control layer, polymerizable monomers and oligomers other than the compound represented by the general formula (I) can also be used in combination.

Examples of polymerizable monomers include styrene, chlorostyrene, α-methylstyrene, divinylbenzene; substituents include methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, Octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2
- acrylates, methacrylates or fumarates with groups such as hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, dimethylaminoethyl, diethylaminoethyl; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3 - poly(meth)acrylates or poly(meth)acrylates such as butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, trimethylolpropane, glycerin and pentaerythritol; vinyl acetate, vinyl butyrate or vinyl benzoate, acrylonitrile, Cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, 2-, 3- or 4-vinylpyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethylacrylamide or N-hydroxyethylmethacrylamide and their alkyl ether compounds ;trimethylolpropane 1
Di- or tri(meth)acrylate of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole; di- or tri(meth)acrylate of diol obtained by adding 2 mole or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol Di(meth)acrylate; 2-hydroxyethyl(meth)acrylate 1
reaction product of 1 mole of phenyl isocyanate or n-butyl isocyanate; poly(meth)acrylate of dipentaerythritol; poly(meth)acrylate of tris-(hydroxyethyl)-isocyanuric acid; tris-(hydroxyethyl)- Poly(meth)acrylate of phosphoric acid; mono(meth)acrylate or di(meth)acrylate of di-(hydroxyethyl)-dicyclopentadiene; pivalic acid ester neopentyl glycol diacrylate; caprolactone-modified hydroxypivalic acid ester neopentyl glycol Examples include diacrylate; linear aliphatic diacrylate; polyolefin-modified neopentyl glycol diacrylate.

Examples of the polymerizable oligomer include caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate.

The liquid crystal material used in the present invention need not be a single liquid crystal compound, but may be a mixture containing two or more liquid crystal compounds or substances other than liquid crystal compounds. Any material that is generally recognized as a liquid crystal material in this technical field may be used, and among these materials, those having positive dielectric anisotropy are preferred. The liquid crystal used is
Nematic liquid crystal, smectic liquid crystal, and cholesteric liquid crystal are preferred, and nematic liquid crystal is particularly preferred.

Examples of liquid crystal materials include 4-substituted benzoic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenyl ester, and 4-substituted cyclohexanecarboxylic acid 4'-substituted phenyl ester. (4-substituted cyclohexanecarbonyloxy)
Benzoic acid 4'-substituted phenyl ester, 4-(4-substituted cyclohexyl)benzoic acid 4'-substituted phenyl ester, 4-(4-substituted cyclohexyl)benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted biphenyl, 4-substituted phenyl-4'-substituted cyclohexane, 4
-substituted 4”-substituted terphenyl, 4-substituted biphenyl 4
'-Substituted cyclohexane, 2-(4-substituted phenyl)-
Examples include 5-substituted pyrimidine.

The proportion of the liquid crystal material in the material constituting the light control layer may be such that the liquid crystal material can form a continuous layer in the light control layer, preferably 40% by weight or more, and preferably in the range of 60 to 90% by weight. Particularly preferred.

Examples of the polymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (
"Darocur 1173" manufactured by Merck & Co., Ltd.), 1-hydroxycyclohexylphenyl ketone (manufactured by Ciba-Geigy "
Irgacure 184"), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one (Merck's "Darocur 1116"), benzyl dimethyl ketal (Ciba-Geigy "Irgacure 6"),
51"), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropanone-1 ("Irgacure 907" manufactured by Ciba Geigy), 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd.) “Kaya Cure DETX”)
and ethyl p-dimethylaminobenzoate (manufactured by Nippon Kayaku Co., Ltd.)
A mixture of isopropylthioxanthone (Kantacure ITX, manufactured by Ward Prekinsop) and ethyl p-dimethylaminobenzoate, acylphosphine oxide (Lucirin LR8728, manufactured by BASF), etc. Can be mentioned.

The proportion of the polymerization initiator used is preferably in the range of 0.5 to 5% by weight, particularly preferably in the range of 1.0 to 3.0% by weight of the polymerizable composition.

If necessary, a photosensitizer, a chain transfer agent, an antioxidant, a thermal polymerization inhibitor, a dye, etc. can be added to the material constituting the light control layer.

The liquid crystal device of the present invention can be manufactured as follows.

That is, on the above substrate having the electrode layer, (1
) A first step of pre-curing the polymerizable composition after applying a light control layer constituent material containing a liquid crystal material, (2) a polymerizable monomer or oligomer, and (3) a polymerization initiator, and a first step of pre-curing the polymerizable composition and pre-curing the light control layer. This method of manufacturing a liquid crystal device is characterized by having a second step of completely curing the polymerizable composition after bonding another substrate onto the layer-constituting material.

[0033] To apply the material constituting the light control layer onto the substrate,
Coating can be performed using a coating machine such as a gravure coater, roll coater, bar coater, or die coater. At that time, the thickness of the light control layer is usually preferably in the range of 5 to 50 μm.

Next, this coated product is precured by irradiating it with ultraviolet rays.

[0035] Precuring is preferably carried out under conditions such that the surface of the coating liquid is exposed to air. Such conditions can be easily achieved using a belt conveyor type ultraviolet irradiation device or a stationary type ultraviolet irradiation device.

By this preliminary curing, the polymerizable composition inside the coating film is cured, and a light control layer having an unreacted polymerizable composition layer can be formed on the surface of the coating film.

The amount of ultraviolet light at this time is preferably 5 to 70% of the amount of ultraviolet light required to completely cure the polymerizable composition.

If the amount of ultraviolet light used for preliminary curing is less than 5%, the internal curing of the coating film will be insufficient, causing pressure unevenness when bonding the other substrate in the next step, resulting in uniformity. This is not preferred because it tends to make it difficult to form a light control layer. In addition, when the amount of ultraviolet light used for pre-curing is more than 70%, the unreacted polymerizable composition layer on the surface of the coating film decreases, and the light control layer and substrate after bonding the other substrate in the next step. This is not preferable because it tends to make it difficult to obtain sufficient adhesion between the two.

Next, the other substrate is bonded onto this precured light control layer constituent material.

Since the light control layer is internally hardened by preliminary curing, it is possible to apply pressure and heat during bonding, and as a result, it is possible to manufacture a liquid crystal device having a light control layer with a uniform thickness. can.

Next, with the light control layer sandwiched between the two substrates, ultraviolet rays or electron beams are irradiated to completely harden the material constituting the light control layer. This operation ensures strong adhesion between the substrate and the light control layer that are bonded later.

The liquid crystal device of the present invention constructed as described above has excellent white turbidity uniformity, high contrast, fast response speed, and excellent adhesion between the light control layer and the substrate. Therefore, by using a substrate made of a transparent plastic film such as polyethylene terephthalate as a substrate, a liquid crystal device having flexibility can be manufactured. Further, by using a substrate made of a strong material such as glass, a strong liquid crystal device can be manufactured.

[0043]

[Examples] Hereinafter, examples of the present invention will be shown to explain the present invention more specifically. However, the present invention is not limited to these examples.

[0044] In the following examples, "%" means "% by weight"
represents.

(Example 1) 40.0% of the liquid crystal composition (A) described below was used as the liquid crystal material, and "Aronix M-5700" (manufactured by Toagosei Kagaku Kogyo Co., Ltd. 2-2) was used as the polymerizable composition.
Hydroxy-3-phenoxypropyl acrylate) 4
8.0%, benzyl acrylate 11.0%, and "Irgacure-184" (photopolymerization initiator manufactured by Ciba Geigy) 1.0%.

[0046] This light control layer constituting material was applied onto an ITO electrode-treated polyester film substrate using an applicator to a thickness of 20.0 microns. This was irradiated with ultraviolet rays of 50 mJ/cm 2 in an air atmosphere using a metal halide lamp having an output of 80 W/cm to pre-cure the material constituting the light control layer.

[0047] Another sheet of ITO is placed on the pre-cured light control layer side.
The electrode-treated polyester film substrates were stacked and bonded together by roller pressure bonding.

[0048] 80W/
800mJ with a metal halide lamp with an output of cm
The material constituting the light control layer was completely cured by irradiating ultraviolet rays of /cm2 to obtain a liquid crystal device. Liquid crystal composition (A) composition

[0049]

[Case 2]

[0050] Transition temperature
154.1℃ (N-I)

The light control layer of the obtained liquid crystal device was uniformly cloudy and had sufficient light-shielding properties so that the light of the fluorescent lamp did not pass through the liquid crystal device.

[0052] Furthermore, the response to ON-OFF switching with respect to the applied voltage was good, and it became transparent at 50V, and the current consumption at that time was 12.2 μA/cm2.

[0053] The obtained liquid crystal device was cut into 10 mm width pieces, two polyester film substrates were pulled using a tensile tester, and the T-peel strength was measured to evaluate the adhesion between the light control layer and the substrate. As a result, 212g
It showed a high value of /10 mm.

At this time, it was observed that the light control layer that had been peeled off was in complete contact with the laminated film substrate, and that it was peeled off at the interface with the coated film substrate.

(Example 2) In Example 1, except that the amount of ultraviolet irradiation during preliminary curing was 150 mJ/cm2,
A liquid crystal device was produced in the same manner as in Example 1.
It had a cloudy light control layer with excellent film thickness uniformity.

The T-peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1, and the result was 146 g/10 m.
It showed a high value of m.

At this time, contrary to the case of Example 1, the peeled light control layer was completely adhered to the film substrate on the coating side, and it was observed that it peeled off at the interface with the film substrate on the laminate side. It was done.

(Example 3) As a liquid crystal material, 70.0% of the liquid crystal composition (B) described later, "Aronix M-5700" was used.
A light control layer constituent material was prepared containing 29.0% of "Irgacure-184" and 1.0% of "Irgacure-184".

This light control layer constituting material was coated to a thickness of 25 microns using a bar coater onto an ITO electrode-treated polyester film substrate on which glass fiber spacers of 25.0 microns were scattered. This was heated for 200 minutes in an air atmosphere using a high-pressure mercury lamp with an output of 80 W/cm.
The material constituting the light control layer was precured by irradiation with mJ/cm2 ultraviolet rays.

[0060] Another sheet of ITO is placed on the pre-cured light control layer side.
The electrode-treated polyester film substrates were stacked and bonded together by roller pressure bonding.

[0061] 80W/
A liquid crystal device was obtained by irradiating ultraviolet rays of 400 mJ/cm 2 with a high-pressure mercury lamp having an output of cm to completely cure the material constituting the light control layer.

Liquid crystal composition (B) composition

[0063]

[Chemical formula 3]

[0064] Transition temperature
98.2℃ (N-I)

The light control layer of the obtained liquid crystal device was uniformly cloudy and had sufficient light-shielding properties so that the light of the fluorescent lamp did not pass through the liquid crystal device.

[0066] Furthermore, the response to ON-OFF switching with respect to the applied voltage was good, and it became transparent at 50 V, and the current consumption at that time was 17 μA/cm 2 .

The T-peel strength of the obtained liquid crystal device was measured in the same manner as in Example 1, and the result was 53 g/10 mm.
It showed a high value.

[0068]

According to the manufacturing method of the present invention, a stable large-area liquid crystal device with excellent adhesion between the light control layer and the substrate can be obtained.

Particularly, in a liquid crystal device having a light control layer formed by forming a three-dimensional network structure of a transparent polymer substance in a continuous layer of liquid crystal material, film thickness uniformity, light control function, and compatibility with double-sided substrates are particularly important. A liquid crystal device having a light control layer with excellent adhesion can be manufactured.

Claims (2)

[Claims] 1. A light control layer constituting material containing a liquid crystal material, a polymerizable composition, and a photopolymerization initiator is interposed between two substrates each having an electrode layer, at least one of which is transparent, and irradiated with ultraviolet rays. In the method for manufacturing a liquid crystal device having a light control layer formed by polymerizing the polymerizable composition to form a three-dimensional network structure of a transparent polymer substance in a continuous layer of a liquid crystal material, A step of pre-curing the polymerizable composition after applying the light control layer constituent material to the light control layer, and a step of laminating the other substrate on the pre-cured light control layer constituent material, followed by a step of pre-curing the polymerizable composition. A method for manufacturing a liquid crystal device, comprising the step of completely curing the liquid crystal device. [Claim 2] The amount of ultraviolet light used for preliminary curing is
2. The method for manufacturing a liquid crystal device according to claim 1, wherein the amount of ultraviolet rays is in the range of 5 to 70% of the amount of ultraviolet light required to completely cure the polymerizable composition.