JPH02309320A - Liquid crystal light control and display material and production thereof - Google Patents

Abstract

PURPOSE:To provide the liquid crystal light control and display material which consists of a liquid crystal occluding thin film layer in sufficient tight contact with a substrate, can be driven with a low voltage and has a sufficient contrast and the process for producing this material by using (meth) acrylate monomer having a specific group in the molecule. CONSTITUTION:This light control and display material contains the liquid crystal as a continuous phase in a high-polymer material having a three-dimensional network structure and is formed between two sheets of substrates, which may have electrodes and at least one of which is transparent. The substrates to be used may be a rigid substrate, such as glass and is most preferably a material having resilience, for example, a plastic film. This liquid crystal light control and display material is the light control and display material to be photoset after the liquid crystal is dissolved into a photosetting compsn., for which the photosetting vinyl compds. of the photosetting compsn., i.e. a series of the (meth) acrylate monomer consisting of the ester of acrylic acid or methacrylic acid, more specifically the (meth) acrylate monomers having the group expressed by formula in the molecule are used.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a liquid crystal encapsulating gJ film that can be formed over a large area. It is a device that can electrically control the transmission of illumination light by restricting, blocking, or transmitting it, and is used in building windows, show windows, viewing-obstructing screens, and curtains for lighting control, as well as displaying characters and figures. ,
By electrically switching the display with high-speed response, it can be used as display devices such as advertising boards, guide boards, decorative display boards, etc.

(Prior Art) As liquid crystal display elements, TN type and STN type devices using nematic liquid crystal have conventionally been put into practical use. Also, devices using ferroelectric liquid crystals have been proposed.

These require a polarizing plate and alignment treatment, and also require precise control of the pitch in order to maintain the screen characteristics, making it difficult to enlarge the screen.

On the other hand, as a method to solve these problems, a method is known in which liquid crystal is microencapsulated, liquid crystal droplets are dispersed in a polymer, and the polymer is formed into a film. Here, gelatin, gum arabic, polyvinyl alcohol, etc. have been proposed as the encapsulating substance (Japanese Patent Laid-Open No. 58-50
No. 1631, UPS No. 4435047).

In the technology disclosed in the above specification, if the encapsulated liquid crystal molecules have positive dielectric constant anisotropy in the thin film, in the presence of an electric field, the liquid crystal molecules move in the direction of the electric field. The refractive index n0 of the liquid crystal and the refractive index n of the polymer
When F is 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 drop becomes n. Due to the deviation, the liquid crystal droplets scatter light at their interfaces, and the thin layer becomes cloudy.

In addition to the above, there are many other known technologies in which liquid crystal fine particles are dispersed in a polymer matrix using encapsulation technology or dispersion technology.

For example, JP-A No. 61-502128 discloses a liquid crystal dispersed in epoxy resin, JP-A No. 62-2231 discloses a liquid crystal dispersed in a special ultraviolet curing resin,
No. 3-271233, No. 63-278035, 63-2
No. 78036 discloses a combination of a photocurable vinyl compound and a liquid crystal.

On the other hand, apart from these technologies, there is a similar liquid crystal light control/display material that has unprecedented features such as being able to be driven by electrical current and contains liquid crystal as a continuous phase in a polymer network structure. Patent application 1986-2 shows what can be achieved by making it into a form
64533.

However, when trying to use a flexible material such as a transparent conductive film as a substrate, the adhesion to the substrate film is poor, which was not a problem when the liquid crystal was dispersed in the form of fine particles in a polymer. The drawback was that it was not possible to create liquid crystal dimming and display materials with high reliability.

(Problems to be Solved by the Invention) As described above, it is possible to fully satisfy (1) that the liquid crystal enclosing thin film layer is in sufficient contact with the substrate, which is required in the practical application of large-sized liquid crystal dimming/display materials, and yet The present inventors have developed liquid crystal light control and display materials that do not require polarizing plates and have the following characteristics as light control and display devices: (ii) they can be driven at low voltages, and (iii) they have sufficient contrast. As far as they know, it has not been possible to produce one.

The present inventors have conducted extensive studies on the structure of liquid crystal light control/display materials and the preferable combination of transparent solid materials used in the light control/display materials, and as a result, the present inventors have found that liquid crystals that satisfy the properties (i) to (iii) We succeeded in producing light control and display materials.

(Means for Solving the Problems) The present inventors have solved the above problem by using a group of (meth)acrylate thread yarns comprising a photocurable vinyl compound of a photocurable composition, that is, an ester of acrylic acid or methacrylic acid. We have found that this can be achieved by carefully selecting the Specifically, the inventors have found that the problem can be solved by using a (meth)acrylate yarn thread having a >P-011 group in the molecule, and have arrived at the present invention.

In the light control/display material of the present invention, the substrate may be made of a rigid material such as glass or metal, but a flexible material such as a plastic film is most suitable. Two substrates can be placed facing each other with an appropriate distance between them. Furthermore, at least one of the substrates must be transparent so that the light control layer supported between the two substrates can be seen from the outside world. However, complete transparency is not required. If this liquid crystal device is to be used to act on light passing from one side of the device to the other, both substrates must have adequate transparency. Appropriate transparent or opaque electrodes may be disposed on the entire surface or part of the substrate depending on the purpose.

A liquid crystal material and a transparent solid component are interposed between the two substrates. Incidentally, it is desirable to interpose a spacer for maintaining the distance between the two substrates according to a conventional method, similarly to a well-known liquid crystal device.

Of course, the liquid crystal material does not need to be a single liquid crystal compound, and may be a mixture containing two or more types of liquid crystal compounds or substances other than liquid crystal compounds, and is usually used as a liquid crystal material in this technical field. Any recognized material may be used, and any material having positive dielectric anisotropy may be used. The liquid crystal used is preferably nematic liquid crystal, smectic liquid crystal, or cholesteric liquid crystal.

Examples of liquid crystal materials include 4-substituted benzoic acid-4'-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid-4'-substituted phenyl ester, 41t'A cyclohexane-4'-substituted biphenyl ester, and 4-substituted cyclohexanecarboxylic acid-4'-substituted phenyl ester. (4-
Z? aCyclohexanecarbonyloxy)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,
Examples include 4-substituted cyclohexylcyclohexane, 4-substituted-4''-substituted terphenyl, 4-substituted biphenyl 4'-it?A cyclohexane, and 2-(4-1tA phenyl)-5-substituted pyrimidine.

Liquid crystal materials require the formation of a continuous layer between two substrates. If the ratio of liquid crystal material components is low, it is difficult to form a continuous phase.

Furthermore, if the ratio of the liquid crystal component is high, the adhesion between the liquid crystal enclosing thin film layer and the substrate decreases, making it impossible to apply it to a flexible substrate. The ratio of the liquid crystal material to the light control layer components is preferably 45
Weight% to 70% by weight, more preferably 50 to 60%
% by weight (hereinafter % means % by weight).

If the transparent solid component present in the continuous phase of this liquid crystal material is dispersed in the form of particles, it is possible to achieve satisfactory display characteristics, but the adhesion between the liquid crystal containing thin film layer and the substrate is low, making it difficult to put it to practical use as a device. I don't get it.

Therefore, the transparent solid component must have a three-dimensional network structure.

Preferably, these liquid crystal light control/display materials can be manufactured as follows. That is, (1) a photocurable material containing a liquid crystal material and a (meth)acrylate compound having a P-011 group between two substrates that are transparent on at least one side, which may have an electrode layer; A solution consisting of the composition is interposed, and then (2) ultraviolet rays are irradiated through the transparent substrate to cure the composition. However, as for the curing temperature conditions, it is preferable to carry out the curing at a temperature equal to or higher than the isotropic liquid transition temperature of the components of the light control layer.
More effectively, it is preferable to carry out the treatment within a range between the isotropic liquid transition temperature of the light control layer constituents and a temperature approximately 10'C higher than the transition temperature.

Examples of (meth)acrylate compounds having a DP-011 group that can be used in the photocurable composition include ethylene oxide-modified phosphoric acid mono(di)acrylate (manufactured by Ohana Kagaku Kogyo Co., Ltd. AR, -200), ethylene oxide-modified phosphorus Acid mono(di)methacrylate (MR- manufactured by Ohana Chemical Industry Co., Ltd.)
200), etc. Ethylene oxide-modified phosphoric acid mono(di)acrylate is preferred from the viewpoint of curability;
The amount used is preferably 20 to 60% by weight in the photocurable composition, particularly preferably 35 to 50% by weight.

In addition to the (meth)acrylic compound having an -o+ group, the photocurable composition preferably contains a polyfunctional (meth)acrylate monomer or oligomer and a polymerization initiator. It may contain optional ingredients depending on the requirements.

Examples of polyfunctional (meth)acrylate monomers include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3
- Poly(meth)acrylates such as butylene glycol, tetramethylene glycol, hexamethylene glycol, trimethylolpropane, glycerin, and pentaerythritol, obtained by adding 2 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol. Di(meth)acrylate of diol,
Triol di- or tri(meth)acrylate obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, and diol di- or tri(meth)acrylate obtained by adding 2 moles or more of ethylene oxide to 1 mole of bisphenol A. Examples include (meth)acrylate, poly(meth)acrylate of dipentaerythol, trimethylpropane triacrylate, tricyclodecane dimethyl diacrylate,
Polyethylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol diacrylate, neopentyl glycol diacrylate, and tris(acryloxyethyl) isocyanurate are preferred in terms of compatibility with the liquid crystal material.

Examples of polyfunctional (meth)acrylate oligomers include: ■ Urethane acrylates with uredane bonds synthesized by polyaddition reaction of polyols, polyisocyanates, and 2-hydroxyalkyl (meth)acrylates ■ Epoxy resins and (meth)acrylic acid Epoxy acrylates synthesized by the addition reaction of polyols,
Polyester acrylate synthesized by polycondensation reaction with polybasic acid and (meth)acrylic acid ■ Polyester synthesized by polycondensation reaction of polyol and polybasic acid, and further polyisocyanate and 2-
Polyester urethane acrylate obtained by polyaddition of hydroxyalkyl (meth)acrylate (2) Examples include polyether acrylate synthesized by a condensation reaction of a polyol having an ether bond in the polymer chain and (meth)acrylic acid.

Examples of the polymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (Darocure 1173J, manufactured by Merck & Co., Ltd.), l-H-F-H-F-H-F-H-H-H-H-H-H--H-H-H-H--H-H-H-H-H--H-H-H-F-H-F-H-H-H-H-H-H (Darocur 1173J manufactured by Merck & Co., Ltd.)
Irgacure 184J), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one (Darocur 1116J manufactured by Merck & Co.), benzyl dimethyl ketal (Irgacure 651J manufactured by Ciba Geigy), 2-methyl- 1-[4-(methylthio)phenyl]-2-morpholinopropanone-1 (Irgacure 907J manufactured by Ciba Geigy), 2,4-diethylthioxanthone (Kayacure DIiTX manufactured by Nippon Kayaku Co., Ltd.)
J) and ethyl p-dimethylaminobenzoate (Kayacure EPAJ manufactured by Nippon Kayaku Co., Ltd.), a mixture of isopropylthioxanthone (manufactured by Ward Breckinsomp Co., Ltd. [Cantercure ITXJ) and ethyl p-dimethylaminobenzoate , acylphosphine oxide (BAS
Examples include "Rushitsun LR8728J" manufactured by Company F.

From the viewpoint of adhesion between the liquid crystal-containing thin film layer and the substrate, crystalline powders such as acylphosphine oxide and benzyl dimethyl ketal are preferred.

The amount of polymerization initiator is preferably O, 1 to 10% by weight, particularly 1 to 6% by weight.

Optional components include photosensitizers, chain transfer agents, antioxidants, thermal polymerization inhibitors, dyes, etc., and may be selected according to the type of polyfunctional monomers, oligomers, etc. and the performance of the desired liquid crystal device. It can be selected as appropriate. In particular, the combined use of a chain transfer agent is extremely effective depending on the type of polyfunctional hexamer or oligomer, and prevents the degree of crosslinking of the resin from becoming too high, thereby allowing the liquid crystal material to respond to the electric field. This makes it easier to respond and exhibits low voltage drive performance.

Good examples of chain transfer agents are butanediol dithioprobionate, pentaerythol tetrakis (β-thiopropionate), triethylene glycol dimercaptan, and the like. The amount of chain transfer agent added varies depending on the type of multifunctional polymer and oligomer used, but if it is too small, the effect will be weak, and if it is too large, the opacity of the liquid crystal device will decrease, resulting in poor contrast of the liquid crystal device. This is not desirable because it tends to The effective amount thereof is preferably 0.05 to 30% by weight, and 0.1 to 30% by weight based on the photocurable composition.
20% by weight is particularly preferred.

j A solution consisting of a liquid crystal material and a photocurable composition containing a (meth)acrylate compound having a P-OH group is
To support between two substrates, this solution may be injected between the substrates, but it is also possible to apply it on one substrate using a coating machine such as a gravure coater, and then stack the other substrate on top of each other. good.

Curing of an uncured solution can be accomplished by irradiating a suitable dose of ultraviolet light through the transparent substrate.

The thickness of the light control layer is usually in the range of 5 to 50 microns.
It will be flied. Alternatively, after semi-curing the uncured coating film with UV light, the other substrate may be stacked on top of the other substrate.

A liquid crystal device configured in this manner enables time-division driving, which was not possible with conventional droplet dispersion type liquid crystal devices, and also has a lower driving voltage and lower contrast than conventional droplet dispersion type liquid crystal devices. It is large and has a fast response speed. Furthermore, it is possible to realize a structure in which the liquid crystal-containing thin film layer is in close contact with the substrate.

Therefore, the liquid crystal device configured in this way is ideal for manufacturing flexible liquid crystal devices using transparent plastic films such as polyethylene terephthalate as substrates, and is suitable for manufacturing flexible liquid crystal devices using transparent plastic films such as polyethylene terephthalate as substrates. , it is possible to fabricate a robust liquid crystal device.

When a plastic film is used as a substrate, there is a great industrial advantage in that large-area liquid crystal devices can be easily mass-produced by commonly known coating and laminating methods.

Furthermore, the liquid crystal device of the present invention changes to a transparent state when the temperature reaches a temperature above which the liquid crystal material undergoes a phase transition to an isotropic liquid phase without applying a voltage, so a liquid crystal material having an appropriate phase transition temperature is selected. By doing so, it can also be used as a temperature-sensitive (temperature-responsive) optical modulation device in a desired temperature range.

(Examples) Hereinafter, the present invention will be described in more detail by showing examples of the present invention, but the present invention is not limited by these examples.

Example 1 "Art Resin UN-2500J (polyester urethane acrylate manufactured by Negami Tamagyo ■)" 13 parts by weight "Visco-1-150J (Osaka Organic Chemical Industry ■)
17 parts by weight rAR-200J (phosphoric acid acrylate monomer manufactured by Ohana Chemical Industry Co., Ltd.) 13 parts by weight Irgacure 184J (manufactured by Ciba Geigy) as a photopolymerization initiator 2 parts by weight rpN-002 (manufactured by Ciba Geigy) Dainichi Ink Chemical Industry q
(gradient nematic liquid crystal) 55 parts by weight were mixed. The above mixture was heated to 75°C to become completely compatible before use.

The above mixture was sandwiched between transparent conductive films sprinkled with spacers in a conventional manner, and cured using a high-pressure mercury lamp at a temperature of 55"C.The applied energy was approximately 1.5"C.
5J/c prayer.

Spacer used: ■15AA (15μ) manufactured by Sumita Optical Glass
(mφ glass fiber) The obtained liquid crystal device was cut into 10 width plates, and the T-peel strength was measured using a tensile tester to evaluate the adhesion between the liquid crystal encapsulating thin film and the film. Ta.

The contrast of the obtained liquid crystal device was 11.9 (OV: ,
・When applying tc100V), no decrease in white turbidity was observed, and stable network formation was achieved.

The characteristics of the liquid crystal material rPN-002j used are as follows.

TRI 85.0'CVt
h t, 26V birefringence △
n 0.269 dielectric constant anisotropy △ε
24.0 Comparative Example 1 rPI? E-116J' (Dainippon Ink Chemical Industry ■
13 parts by weight [Viscoat 3700 J (Polyester acrylate manufactured by Osaka Organic Chemical Industry ■) 13 parts by weight
Parts by weight [Aloex M-1174' (acrylate monomer manufactured by Toagosei Chemical Co., Ltd.) 17 parts by weight Irgacure 651J (manufactured by Chiha Geigy) as a photopolymerization initiator 2 parts by weight Other than using rpN-002J as a liquid crystal material A liquid crystal device was obtained in the same manner as in Example 1. (The curing temperature was 35'
C) Adhesion was evaluated in the same manner as in Example 1.2.
It was 3g/10mm.

Further, the contrast at 550 nm was 1:1.2, and after several hours, destruction of the network occurred and a decrease in white turbidity was observed.

In addition, polyester urethane acrylate PRE-116
was prepared as follows.

In a 11-four-bottle flask equipped with a stirrer, a thermometer, and a condenser, add 500 g of Frapol L-2010J (■ Polyester polyol manufactured by Kuraray), 2.4-tolylene diisocyanate (TDI-1oo) 85 bis, octylic acid No. 1 0.03 g of tin was charged, the temperature was raised to 60°C, and the reaction was carried out for 1 hour. Next, 65 g of hydroxypropyl acrylate and 0.3 g of t-butylhydroquinone were added.
, 0.06ε of stannous octylate was charged, and the reaction was carried out at 70°C for 8 hours. The isoneanate group content was 0%, and the viscosity of the xylene:reaction product-3nia (weight ratio) was T -11 polyester urethane acrylate (PR[1-116) was quantitatively obtained.

Comparative Example 2 [Art Resin uN-2500J (polyester urethane acrylate manufactured by Nedo Kogyo ■) 17 parts by weight [Viscoat 150J (acrylate monomer manufactured by Osaka Organic Chemical Industry ■) 26 parts by weight Irgacure 184J (manufactured by Ciba Geigy) as a photopolymerization initiator ) A liquid crystal device was obtained in the same manner as in Example 1, except that 2 parts by weight of rpN-002J was used as the liquid crystal material. (Curing temperature was 35°C) Adhesion was evaluated in the same manner as in Example 1. Where I did it, 0
-6 g/10mm.

Further, the contrast at 550 nm was 1:1.2, and after several hours, destruction of the network occurred and a decrease in white turbidity was observed.

(Effects of the Invention) Since the liquid crystal device of the present invention has excellent adhesion between the liquid crystal containing thin film and the substrate, it is possible to easily manufacture a liquid crystal device with stable white turbidity and large area and flexibility.

Claims (1)

[Claims] 1. A light control/display containing a liquid crystal material as a continuous phase in a polymeric material having a three-dimensional network structure between two substrates, at least one of which is transparent, which may have electrodes. In dimming/display materials that are photocurable after dissolving liquid crystals in a photocurable composition, (meth)acrylates containing ▲ mathematical formulas, chemical formulas, tables, etc. are included in the photocurable composition. A liquid crystal light control/display material characterized by containing a compound. 2. The photocurable composition contains a) a compound group selected from (meth)acrylate monomers or oligomers containing at least one difunctional or more reactive functional group; b) ▲ in the molecule.
There are mathematical formulas, chemical formulas, tables, etc. The liquid crystal light control/display material according to claim 1, comprising a (meth)acrylate compound having a ▼ group and c) a polymerization initiator. 3. The ratio of liquid crystal substance to photocurable composition is 45: by weight.
The liquid crystal light control/display material according to claim 1 or 2, characterized in that the ratio is in the range of 55 to 70:30. 4. The liquid crystal light control/display material according to claim 1, wherein the light control layer has a thickness of 5 to 50 microns. 5. The liquid crystal light control/display material according to claim 1, wherein the liquid crystal material is a mixture of one or more selected from the group consisting of nematic liquid crystal, smectic liquid crystal, and cholesteric liquid crystal. 6. A step in which a solution consisting of a liquid crystal material and a photocurable composition containing a (meth)acrylate compound having a ▲ mathematical formula, chemical formula, table, etc. group is interposed between two substrates, and the solution is A method for producing a liquid crystal dimming/display material, comprising the step of curing by light irradiation under conditions that maintain an isotropic liquid state.