JP2002098943A - Optical element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element, capable of reversibly controlling the degree of reflection and the existence of reflection by applying electric field and having operating voltage lower than that of a conventional optical element, formed in a multi-layered structure of a liquid crystal and a polymerized cured matter, and to provide its manufacturing method. SOLUTION: The optical element consists of a 55-68 wt.% liquid crystal material and the polymerized/cured matter of a polymeric composition containing a 30-43 wt.% polymeric compound and 2-15 wt.% photopolymerization initiator between two transparent substrates, having an electrode layer and has the multi-layered structure, where the liquid crystal material and the polymerized/cured matter of the polymeric composition are layered alternately and repetitively, and the contents of the liquid crystal material and the polymerized/cured matter of the layers alternately formed are different by each layer and refractive index periodically varies. Its manufacturing method are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively transmitting and reflecting ultraviolet, visible, and near-infrared light by applying an electric field or the like, and reversibly controlling the degree of reflection.
The present invention relates to an optical element or an optical display element that can be used for an optical filter, a liquid crystal display element, a liquid crystal light adjusting element, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as an optical element or an optical display element capable of selectively transmitting and reflecting light having a wavelength in the ultraviolet, visible, and near-infrared ranges, a thin film of metal or the like deposited on glass or a hologram is used. Known display elements are those that record interference light on silver salts or photosensitive materials, and are used for infrared cut filters, etc., and are also used for head-up displays, high-mount stop lamps, and three-dimensional three-dimensional displays. Are being considered.

Further, a mixture containing a photocurable uncured product and a liquid crystal is irradiated with interference light to cure the photocured product, and has a layered structure in which the refractive indexes of the liquid crystal and the cured product alternately and periodically change. However, there has been proposed an optical element or the like capable of changing the refractive index of liquid crystal by applying an electric field thereto and reversibly controlling the degree of reflection and the presence or absence of reflection. (For example, JP-A-4-355424).

[0004] However, a thin film of a metal or the like deposited on glass, a volume hologram optical element or a display element using a hologram, the degree of transmission or reflection at a specific wavelength is always constant. It has been desired to be able to reversibly control the degree of reflection and the presence or absence of reflection.

On the other hand, an optical element having a multilayer structure of a liquid crystal and a cured polymer can reversibly control the degree of reflection by applying an electric field. However, the high driving voltage is a barrier to practical application.
It is strongly desired to reduce the driving voltage of the device.

[0006]

SUMMARY OF THE INVENTION Accordingly, the problem to be solved by the present invention is that the degree of reflection and the presence or absence of reflection can be reversibly controlled by applying an electric field. It is an object of the present invention to provide an optical element having a lower voltage than an optical element formed by a multilayer structure of a polymer and a cured product, and a method for producing the same.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a polymerizable composition comprising a liquid crystal material having a specific composition ratio and a polymerizable compound is polymerized by interfering light irradiation. The inventors have found that an optical element having a low voltage and a high reflectance can be obtained, and have completed the present invention.

That is, the present invention provides: (1) 55-68% by weight of a liquid crystal material (A) between two transparent substrates having an electrode layer and (B) a polymerizable compound 30-43.
% By weight, and (C) a polymerized composition of a polymerizable composition containing 2 to 15% by weight of a photopolymerization initiator, wherein a liquid crystal material and a polymerized cured product of the polymerizable composition are alternately repeated. And an optical element whose refractive index changes periodically, wherein the content of the liquid crystal material and the polymerized and cured product of the alternately formed layers differs depending on the layer,

(2) The optical element according to (1), wherein (A) the liquid crystal material contains a liquid crystal having a trans skeleton or a cyano group at a terminal;

(3) The polymerizable compound (B) has 5 to 5 carbon atoms.
An optical element according to (1) or (2), which is a (meth) acrylate having 25 alkyl groups in a side chain;

(4) The optical element according to (1), (2) or (3), wherein the polymerizable compound (B) further contains a monofunctional (meth) acrylate.

(5) The layer having a large content of the liquid crystal material is characterized in that the liquid crystal material is covered with a polymer and formed so as to include an independently existing droplet state. An optical element according to any one of the above,

(6) The optical element according to any one of (1) to (5), wherein the distance between the layer mainly composed of a liquid crystal material and the layer mainly composed of a cured polymer is changed for each pixel electrode.

(7) 55-68% by weight of a liquid crystal material (A), 30-43% by weight of a polymerizable compound, and (C) photopolymerization initiation between two transparent substrates having an electrode layer. Agent 2
A polymerizable composition containing 15% by weight is polymerized by irradiation with interference light. The polymerizable compound has a multilayer structure in which a liquid crystal material and a polymerizable compound are alternately repeated, and contains a liquid crystal material and a polymerizable compound in alternately formed layers. A method of manufacturing an optical element in which the amount differs depending on the layer and the refractive index changes periodically.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a multilayer structure in which a liquid crystal material and a polymer cured product are alternately repeated may be parallel to a transparent substrate having an electrode layer or inclined at a specific angle. You may. A multilayer structure in which a liquid crystal material and a polymer cured product are alternately repeated becomes a reflective optical element when it is nearly parallel to a transparent substrate surface having an electrode layer, and becomes a transmission optical element when it is nearly perpendicular. .

In the case of a reflection type optical element, of the light incident on the optical element, only light of a specific wavelength or wavelength range is reflected, and other incident light is almost transmitted. In the case of a transmission type optical element, light incident on the optical element is split and transmitted and reflected.

FIG. 1 shows an example of a cross section of a reflective optical element manufactured according to the present invention. In FIG. 1, 1 indicates a transparent substrate, 2 indicates a transparent electrode, 3 indicates a layer containing a large amount of liquid crystal, and 4 indicates a layer containing a large amount of a cured polymer. FIG. 2 shows an example of a cross section of a transmission type optical element manufactured according to the present invention.

In FIG. 2, reference numeral 1 denotes a transparent substrate,
Indicates a transparent electrode, 3 indicates a layer containing a large amount of liquid crystal, and 4 indicates a layer containing a large amount of a cured polymer. 1 and 2 show a structure in which a liquid crystal material is covered with a polymer and the liquid crystal material is covered with a polymer, and includes a droplet state that exists independently, or a structure in which the liquid crystal material communicates.

The structure in which the liquid crystal material is covered with the polymer and includes the droplet state which exists independently is the structure in which the liquid crystal material is covered with the polymer and exists independently in the droplet state, or the structure in which the liquid crystal material is in the polymer state. And a structure in which a liquid crystal material and a structure in which the liquid crystal material is communicated to some extent are mixed.

Depending on the polymerization rate of the polymerizable compound and the ratio of the liquid crystal material, the layer having a large liquid crystal content of 3 shows a structure in which the liquid crystal material is covered with the polymer and includes an independently existing droplet state. Or a structure in which liquid crystal materials communicate with each other. In the case of a structure in which a liquid crystal material is covered with a polymer and includes an independently existing droplet state, the drive voltage of the optical element tends to increase as the ratio of the liquid crystal droplet state increases. Therefore, a structure in which the droplet state of the liquid crystal is smaller is preferable because the driving voltage is lower.

FIG. 3 shows an example of a specific method for manufacturing the reflection type optical element of the present invention. In FIG. 3, a cell is formed using a transparent substrate with two electrodes, and a liquid crystal material (A), a polymerizable compound (B), and a photopolymerization initiator (C) of the present invention are formed in the cell. And a polymerizable composition containing

A coherent light such as a laser beam from a 5Ar laser is expanded in optical axis diameter by a beam expander 6, is split into two beams by a beam splitter 7, and a mirror 8
The composition is irradiated from two directions by using, for example, two lights to interfere with each other to generate interference light, and the interference light is irradiated.

In the bright portion of the interference light, the polymerization of the polymerizable compound proceeds preferentially, whereby the solubility of the liquid crystal in the bright portion of the interference light decreases, and the liquid crystal is discharged from the bright portion of the interference light and polymerized and cured. To form a layer with a high content of substances. On the other hand, in the dark portion of the interference light, the polymerization of the polymerizable compound does not proceed, and the liquid crystal discharged from the bright portion of the interference light is added, thereby forming a layer having a large liquid crystal content. Thereby, an optical element having a multilayer structure in which the refractive index of the layer 3 having a large content of liquid crystal and the layer 4 of FIG. .

The refractive index of the layer containing a large amount of liquid crystal is higher than the refractive index of the layer containing a large amount of the cured polymer. Due to the difference between the two refractive indices of the multilayer structure of such a layer, Bragg diffraction expressed by the equation (1) occurs, and among the light incident on the optical element,
Reflects light of a specific wavelength.

Formula (1) 2d SIN θ = nλ (where d is the distance between the centers of the layer containing a large amount of liquid crystal and the layer containing a large amount of the cured polymer, θ is the Bragg angle, and λ is the wavelength of the reflected light. , N represents the order)

The wavelength of the reflected light is determined by the Bragg's equation shown in the equation (1), based on the distance between the centers of the layer containing a large amount of liquid crystal and the layer containing a large amount of the cured polymer. When it is desired to reflect only light of a specific wavelength, if the distance between the center of the layer containing a large amount of liquid crystal and the layer containing a large amount of a cured polymer formed in the optical element is kept constant, only the specific wavelength Can be reflected. Also, when reflecting light in a certain wavelength range, the light in that wavelength range causes diffraction,
What is necessary is just to form a layer interval between a layer having a large content of liquid crystal and a layer having a large content of the polymerized cured product.

The reflectance at a specific wavelength by the reflection type optical element of the present invention is determined by the difference between the refractive index of a layer having a large content of liquid crystal and the layer having a large content of a cured polymer, the number of repetitions of the layer structure,
In other words, it is determined by the thickness of the entire multilayer structure, and the reflectance increases as the thickness of the entire multilayer structure increases.

The larger the difference in refractive index between the layer containing a large amount of liquid crystal and the layer containing a large amount of the polymer cured product, the higher the reflectance becomes. It is desirable to increase the difference between the refractive indices of the layers with a large amount.
Therefore, the thickness of the multilayer structure composed of the layer having a large content of liquid crystal and the layer having a large content of the polymerized cured product is similar if the difference in the refractive index is large and the thickness is small if the difference in the refractive index is small. Rate is obtained.

However, when the reflectivity is reversibly changed by a voltage or the like, if the thickness of the entire multilayer structure is large,
The driving voltage increases. Therefore, it is preferable to reduce the thickness by increasing the difference in refractive index between the layer having a large content of liquid crystal and the layer having a large content of the polymerized cured product, and the thickness of the entire multilayer structure is preferably 2 to 50 μm. preferable.

In order to control the degree of reflection and the presence or absence of reflection reversibly, an electric field or a magnetic field is applied to the element to change the refractive index of the liquid crystal in the element. This can be achieved by continuously changing the difference in refractive index between the layer having a large amount of the polymer and the layer having a large content of the polymerized and cured product of 4.

When a voltage is applied, the liquid crystal is oriented in the direction of the electric field,
Since the difference between the refractive index of the layer containing a large amount of liquid crystal and the refractive index of the layer containing a large amount of the cured polymer decreases, the reflectance decreases. By controlling the applied voltage, it is possible to continuously control the reflectance at a specific wavelength.

In the case of a reflection-type element, the distance between a layer containing a large amount of liquid crystal and a layer containing a large amount of a polymerized and cured product is kept constant, and an electrode is formed for each pixel, so that monochromatic characters and pictures can be formed. It can be displayed. Further, for each pixel electrode, a layer having a large content of liquid crystal and a layer having a large content of a polymerized cured product are represented by R
By forming them at intervals that generate reflected light corresponding to three colors of GB, color display can be performed without using a color filter or the like.

As a method of forming a layer containing a large amount of liquid crystal and a layer containing a large amount of a cured polymer at each pixel electrode at intervals to generate reflected light corresponding to three colors of RGB, for example, an electrode layer A liquid crystal material, a polymerizable compound, and a photopolymerization initiator are interposed between two transparent substrates having a light-shielding mask in two of the three colors of RGB, green and blue, and a red portion is formed. Irradiation of interference light is performed only between the layers to cause red reflection. Next, the light-shielding mask of the green portion is removed, and interference light is emitted to form a layer interval that causes green reflection. Finally, the light-shielding mask in the blue portion is removed, and interference light is emitted to form a layer interval that causes blue reflection.

Since the optical element of the present invention is composed of a liquid crystal and a polymer cured product as compared with a conventional volume hologram optical element made of a resin, an optical element having a large refractive index difference between layers and having a high diffraction efficiency can be obtained. Become. Further, the manufacturing method of the present invention does not require a special material such as that used for a normal volume hologram, and after curing, removes a specific material or impregnates with another material as described in WO 91-10926. The productivity is good because there is no need to do it.

The substrate used in the present invention may be a rigid material, for example, glass, etc.
For example, it may be a plastic film. The two substrates are to be obtained facing each other at an appropriate distance. They must also be transparent and allow the multilayer structure sandwiched between the two to be visible from the outside world. However, complete transparency is not essential.

A transparent electrode may be disposed on the entire surface or a part of the substrate depending on the purpose. Further, an active matrix substrate provided with an active element such as a thin film transistor (TFT), a thin film diode, a metal insulator, and a metal non-linear resistance element (MIM) for each pixel electrode may be used.

In order to control the overall thickness of the multilayer structure composed of the liquid crystal and the polymerized and cured product, a spacer for maintaining a space may be interposed between the two substrates, similarly to a well-known liquid crystal device. . The spacer may be mixed with a solution containing a liquid crystal material and a cured polymer, or may be applied on a substrate. As a spacer, for example, mylar,
Various types of liquid crystal cells such as alumina, rod-type glass fibers, glass beads, and polymer beads can be used without particular limitation.

The liquid crystal material used in the present invention does not need to be a single liquid crystal compound. Characteristics of liquid crystal materials, that is, phase transition temperature, melting point, viscosity, Δ of isotropic liquid and liquid crystal
For the purpose of improving n, Δε, solubility with a polymerizable compound, and the like, a composition of two or more liquid crystal compounds may be used, and may be appropriately selected and blended. Usually, any material may be used as long as it is recognized as a liquid crystal material in this technical field, and it is sufficient if the manufactured optical element is a liquid crystal capable of obtaining good characteristics.

The liquid crystal material (A) used in the present invention is preferably a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal or the like, and particularly preferably a nematic liquid crystal.
In order to improve the performance, cholesteric liquid crystal,
Chiral compounds such as chiral nematic liquid crystals and chiral smectic liquid crystals may be included.

These liquid crystal materials (A) include benzoate esters, cyclohexane carboxylate esters,
Biphenyl, terphenyl, phenylcyclohexanoic acid, pyrimidine, pyridine, dioxane, cyclohexanecyclohexane ester, tolan, alkenyl, fluoro, cyano, naphthalene, etc. represented by the following general formula (2) The liquid crystal compound represented can be used. General formula (2)

[0041]

Embedded image

(Wherein rings A, B and C are each independently
Represents any ring shown in Chemical formula 2,

[0043]

Embedded image

N is an integer of 0 to 2; m is an integer of 1 to 4;
1 and Y2 are, each independently, a single bond, -CH ₂ C
H ₂ —, —CH ₂ O—, —COO—, —OCO—, —C}
C-, -CH = CH-, -CF = CF-,-(-C
_{H 2) 4 -, - CH} 2 CH 2 CH 2 O-, or -CH ₂ = CH
Represents CH ₂ —, and Y 3 represents a single bond, —COO—, or —
Represents OCO-, and R independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkenyl group, an alkenyloxy group, a fluoroalkyl group, or a fluoroalkoxy group. Among them, it is preferable to use a liquid crystal material including a tolan liquid crystal and a cyano liquid crystal.

The polymerizable compound (B) used in the present invention includes, for example, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate , Stearyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methyl carbitol (meth) acrylate, ethyl carbitol (meth) acrylate , Cyclohexyl (meth) acrylate,

Isobornyl (meth) acrylate, 2-
Hydroxyethyl (meth) acrylate, phenoxy (meth) acrylate, methoxydipropylene glycol (meth) acrylate, trifluoroethyl (meth)
Acrylate, dimethylamino (meth) acrylate,
Morpholinoethyl (meth) acrylate, perfluoroalkyl (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, aliphatic di (meth) acrylate, epichlorohydrin Modified 1,6-hexanediol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, bisphenol A di (meth) acrylate,

Epichlorohydrin-modified bisphenol A
Di (meth) acrylate, ethylene oxide-modified bisphenol A di (meth) acrylate, propylene oxide-modified bisphenol A di (meth) acrylate,
Butylene oxide-modified bisphenol A di (meth) acrylate, 3,3-dimethylolpentanedi (meth)
Acrylate, 3,3-dimethylol heptane di (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate And acrylic ester monomers such as dipentaerythritol hexa (meth) acrylate;

N, N-dimethylacrylamide, N, N
Acrylamide compounds such as dimethylaminopropylacrylamide, urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, oligoester acrylate, hydroxybivalic acid ester neopentyl glycol di (meth) acrylate, caprolactone-modified hydroxyviva Phosphate ester neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, fluorinated alkyl di (meth) ) Acrylate, having 5 to 2 carbon atoms
Examples thereof include (meth) acrylate having an alkyl group of 5 in a side chain, but are not particularly limited thereto.

Among the polymerizable compounds (B) used in the present invention, (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain is particularly preferably used. here,
The main chain structure of the (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain is not particularly limited as long as it is a structure used as a normal acrylate. The number of side chain groups may be one or more per one molecule of (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain.

The number of functional groups in one molecule of the (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain may be 2 or more, and the number is not particularly limited. In order to increase the polymerization rate of the polymerizable composition comprising the polymerizable compound and the photopolymerization initiator, the number of the functional groups may be increased, and the manufactured optical element may be appropriately timed so as to obtain good characteristics. Just choose.

The polymerizable compound (B) used in the present invention comprises:
One type of polymerizable compound may be used, or two or more types of polymerizable compounds may be used in combination as long as the effect of the present invention is not impaired, and further contains a known and commonly used monofunctional (meth) acrylate. You can also. The polymerizable compound (B) may be a uniform solution or a non-uniform solution, but preferably a uniform solution. It is also possible to mix the liquid crystal with the liquid crystal in an uncured state, and the mixture mixed with the liquid crystal is preferably a uniform solution.

Examples of the polymerization initiator used in the present invention include 2-hydroxy-2-methyl-1-phenylpropan-1-one (Darocur 117 manufactured by Merck & Co., Inc.).
3 "), 1-hydroxycyclohexylphenyl ketone (" Irgacure 184 "manufactured by Ciba-Geigy), 1-
(4-Isopropylphenyl) -2-hydroxy-2-
Methylpropan-1-one (Darocur 1 made by Merck)
116 "), benzyldimethyl ketal (" Irgacure 651 "manufactured by Ciba-Geigy), 2-methyl-1-
[4- (Methylthio) phenyl] -2-morpholinopropanone-1 ("Irgacure 90" manufactured by Ciba-Geigy)
7 "),

2,4-diethylthioxanthone ("Kayacure DETX" manufactured by Nippon Kayaku Co., Ltd.) and ethyl p-dimethylaminobenzoate ("Kayacure EPA" manufactured by Nippon Kayaku Co., Ltd.)
And a mixture of isopropylthioxanthone ("Cantacure ITX" manufactured by Ward Prekinsopp Co.) and ethyl p-dimethylaminobenzoate.

When the proportion of the liquid crystal material used in the polymerizable composition increases, the driving voltage tends to decrease. However, when the ratio of the liquid crystal material is too high, the polymerization rate of the polymerizable compound is reduced, and it is difficult to form a multilayer structure of the liquid crystal material and the polymerizable compound. Therefore, the types and proportions of the liquid crystal material, the polymerizable compound, and the photopolymerization initiator should be adjusted in a timely manner so that the characteristics of the optical element after fabrication according to the types and proportions of the liquid crystal material, the polymerizable compound, and the photopolymerization initiator become good. You have to choose.

FIG. 4 shows an example of the relationship between the liquid crystal concentration and the drive voltage (drive voltage per unit cell thickness), and FIG. 5 shows an example of the relationship between the liquid crystal concentration and the reflectance. When the ratio of the liquid crystal material in the polymerizable composition increases, the driving voltage tends to decrease. On the other hand, the reflectance tends to decrease as the usage ratio of the liquid crystal material increases. However, surprisingly, it has been found that the reflectivity tends to increase when the ratio of the liquid crystal material exceeds about 48%, and that the reflectivity greatly increases at 55% by weight or more.

In other words, there is an optimum value between the liquid crystal density and the reduction of these driving voltages and the high reflectance. For this reason, the proportion of the liquid crystal material (A) in the polymerizable composition of the present invention is preferably in the range of 55 to 68% by weight, and more preferably in the range of 57 to 65% by weight. (B) The ratio of the polymerizable compound is preferably in the range of 30 to 43% by weight, and more preferably in the range of 30 to 38% by weight. The proportion of the photopolymerization initiator (C) is preferably in the range of 2 to 15% by weight, more preferably in the range of 5 to 13% by weight.

As the energy beam for polymerization, it is sufficient that interference light can be formed and the polymerizable composition can be polymerized, and specifically, a temporally and spatially coherent light such as a laser beam is preferable. The irradiation intensity and the irradiation amount of the interference light require a certain intensity or amount, but are influenced by the reactivity of the polymerizable composition and the type and concentration of the photopolymerization initiator. Therefore, the optimum irradiation intensity and irradiation amount may be appropriately selected.

[0058]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below to explain the present invention in detail. However, the invention is not limited to these examples. In the following examples, “%” represents “% by weight”, and each of the evaluation characteristics means the following symbols and contents.

The intensity of the ultraviolet light was measured using a unimeter “UIT-101” manufactured by Ushio Inc. and a light receiving element “UVD-365P”.
D ". The reflectance was measured by measuring the transmittance of the sample using a spectrometer U-3500 (manufactured by Hitachi, Ltd.), and the decrease in transmittance due to reflection was defined as the reflectance.

ROFF: reflectance (%) when no voltage is applied, Vr
90: ROFF is set to 100%, the reflectance is 10% when the reflectance is set to 0% when the decrease in the reflectance is saturated by applying a voltage.
%, Applied voltage (Vrms), λ: center wavelength of reflected light
(nm)

(Example 1) 58% of a liquid crystal material having a tran skeleton (manufactured by Dainippon Ink and Chemicals, Inc.), 30% of polyethylene glycol diacrylate NK ester A400 (manufactured by Shin-Nakamura Chemical Co., Ltd.), and "C10
1 "(manufactured by Toagosei Co., Ltd.), 12% of the polymerizable composition was injected between two glass cells with an ITO electrode having a cell thickness of about 11 µm, and the whole substrate was kept at about 25 ° C.

As a light source for exposure, an argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used, a parallel beam having an optical axis diameter of about 10 mm was obtained by a beam expander, and two light beams were obtained by using a beam splitter. After that, by irradiating the polymerization composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element.
As a result of measuring various characteristics of this optical element, ROFF = 13
(%), Vr90 = 82 Vrms, and λ = 460 (nm).

Example 2 A liquid crystal material having a tran skeleton (manufactured by Dainippon Ink and Chemicals, Inc.) 58%, and the main chain skeleton was EC
H-modified 1,6-hexanediol diacrylate, 32% of acrylate having 2 side chain groups and 11 side chain alkyl groups (Dainippon Ink & Chemicals, Inc.), and "C101" as a polymerization initiator A polymerizable composition consisting of 10% (manufactured by Toagosei Co., Ltd.) was injected between two glass electrodes with an ITO electrode having a cell thickness of about 11 μm, and the entire substrate was kept at about 25 ° C.

As a light source for exposure, an argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used, and a parallel beam having an optical axis diameter of about 10 mm was converted by a beam expander into two light beams using a beam splitter. Thereafter, by irradiating the polymer composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element.
As a result of measuring various characteristics of this optical element, ROFF = 25
(%), Vr90 = 20 Vrms, and λ = 460 (nm).

(Example 3) A liquid crystal material having a tolan skeleton (manufactured by Dainippon Ink and Chemicals, Inc.) 58%, and the main chain skeleton was EC
H-modified 1,6-hexanediol diacrylate, acrylate having 2 side chain groups and 11 side chain alkyl groups (Dainippon Ink & Chemicals, Inc.) 28%, lauryl acrylate (manufactured by Kyoei Yushi Co., Ltd.) A polymerizable composition consisting of 4% and 10% of “C101” (manufactured by Toagosei Co., Ltd.) as a polymerization initiator was injected between two glass electrodes with an ITO electrode having a cell thickness of about 11 μm, and the entire substrate was dried for about 25 minutes. C. was maintained.

An argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used as a light source for exposure, a parallel beam having an optical axis diameter of about 10 mm was obtained by a beam expander, and two light beams were obtained by using a beam splitter. After that, by irradiating the polymerization composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element. As a result of measuring various characteristics of this optical element, ROFF = 2
0 (%), Vr90 = 18 Vrms, and λ = 460 (nm).

Example 4 A liquid crystal material having a tran skeleton (manufactured by Dainippon Ink and Chemicals, Inc.) 64%, and the main chain skeleton was EC
H-modified 1,6-hexanediol diacrylate, 24% of an acrylate having 2 side chain groups and 11 side chain alkyl groups (Dainippon Ink and Chemicals, Inc.), and "C101" as a polymerization initiator (Toa Gosei Co., Ltd.) A polymerizable composition consisting of 12% was coated with two sheets of ITO having a cell thickness of about 11 μm.
It was injected between glass cells with electrodes, and the whole substrate was kept at about 25 ° C.

As an exposure light source, an argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used, and a parallel beam having an optical axis diameter of about 10 mm was converted by a beam expander into two light beams using a beam splitter. Thereafter, by irradiating the polymer composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element.
As a result of measuring various characteristics of this optical element, ROFF = 18
(%), Vr90 = 15 Vrms, and λ = 460 (nm).

(Example 5) Cyano liquid crystal RO571
58% (manufactured by Dainippon Ink and Chemicals, Inc.), main chain skeleton is EC
H-modified 1,6-hexanediol diacrylate, 34% of an acrylate having 2 side chain groups and 7 alkyl side chain groups (manufactured by Dainippon Ink and Chemicals, Inc.), and "C101" as a polymerization initiator Consisting of 8% (manufactured by Toagosei Co., Ltd.)
The polymerizable composition was injected between two glass cells with an ITO electrode having a cell thickness of about 11 μm, and the entire substrate was kept at about 25 ° C.

An argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used as a light source for exposure, and a parallel beam having an optical axis diameter of about 10 mm was converted by a beam expander into two light beams using a beam splitter. Thereafter, by irradiating the polymer composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element.
As a result of measuring various characteristics of this optical element, ROFF = 12
(%), Vr90 = 36 Vrms, and λ = 460 (nm).

(Example 6) A liquid crystal material having a tran skeleton (manufactured by Dainippon Ink and Chemicals, Inc.), the main chain skeleton is ECH-modified 1,6-hexanediol diacrylate, the number of side chain groups is 2, and the side chain groups The polymerizable composition was prepared by changing the concentration ratio of the acrylate having an alkyl number of 11 (manufactured by Dainippon Ink and Chemicals, Inc.) and the polymerization initiator “C101” (manufactured by Toagosei Co., Ltd.). Each has a cell thickness of about 11 μm
, And the entire substrate was kept at about 25 ° C.

As an exposure light source, an argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 watts) was used.
/ M ² ) and a beam expander with an optical axis diameter of about 10
mm, and then irradiating the polymer composition in the glass cell from two directions with interference light for 300 seconds to obtain a plurality of optical elements by irradiating the polymer composition in two directions with a beam splitter. .

FIGS. 4 and 5 show the results of measuring various characteristics of these optical elements. FIG. 4 shows the result of the driving voltage (VR'90) per unit cell thickness when the ratio of the liquid crystal material in the polymer composition was changed, and FIG. 5 shows the result of changing the ratio of the liquid crystal material in the polymer composition. In the case, the result of the reflectance when no voltage is applied is shown.

(Comparative Example 1) 45% of a liquid crystal material having a tran skeleton (manufactured by Dainippon Ink and Chemicals, Inc.), 45% of polyethylene glycol diacrylate NK ester A400 (manufactured by Shin-Nakamura Chemical Co., Ltd.), and "C101" as a polymerization initiator "
A polymerizable composition consisting of 10% (manufactured by Toagosei Co., Ltd.) was injected between two glass electrodes with an ITO electrode having a cell thickness of about 11 μm, and the entire substrate was kept at about 25 ° C.

As an exposure light source, an argon laser (wavelength: 363.8 mm, ultraviolet intensity: about 800 W / m ² ) was used, and a parallel beam having an optical axis diameter of about 10 mm was converted by a beam expander into two light beams using a beam splitter. Thereafter, by irradiating the polymer composition in the glass cell from two directions, interference light was irradiated for 300 seconds to obtain an optical element.

As a result of measuring various characteristics of this optical element, R
OFF = 8 (%), Vr90 = 470Vrms, λ = 460 (nm)
Met. The optical element obtained in Comparative Example 1 had a higher driving voltage and a lower reflectance than the optical element obtained in the example.

[0077]

According to the present invention, by applying an electric field,
Provided is an optical element capable of reversibly controlling the degree of reflection and the presence or absence of reflection and having an operating voltage lower than that of an optical element formed by a conventional multilayer structure of liquid crystal and a polymer cured product, and a method of manufacturing the same. can do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cross-sectional view of a reflective optical element of the present invention.

FIG. 2 is a schematic view of a cross-sectional view of a transmission type optical element of the present invention.

FIG. 3 is a schematic view showing one example of a light irradiation method in the production of the reflection type optical element of the present invention.

FIG. 4 is a diagram showing a relationship between a liquid crystal material (% by weight) in a polymerizable composition and a driving voltage (VR'90) per unit cell thickness of an optical element.

FIG. 5 is a graph showing a relationship between a liquid crystal material (% by weight) in a polymerizable composition and a reflectance (%) of an optical element.

[Explanation of symbols]

 1: Transparent substrate 2: Transparent electrode 3: Layer having a large content of liquid crystal 4: Layer having a large content of a cured polymer 5: Ar laser 6: Beam expander 7: Beam splitter 8: Mirror 9: Transparent cell

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02F 1/13 500 G02F 1/13 500 505 505 F term (reference) 2H048 FA04 FA13 FA16 FA24 2H049 AA02 AA06 AA12 AA25 AA34 AA43 AA51 AA58 CA05 CA10 CA15 CA24 CA28 2H088 EA31 GA02 GA10 MA20 2H089 JA04 KA04 KA08 NA60 QA11 QA16 TA02 UA09 4H027 BA01 BE01 BE04

Claims (7)

[Claims] 1. A method according to claim 1, further comprising the step of:
(A) 55 to 68% by weight of a liquid crystal material, (B) 30 to 43% by weight of a polymerizable compound, and (C) 2 to 15% of a photopolymerization initiator.
% By weight of a polymerizable composition of a polymerizable composition, wherein the liquid crystal material and the polymerizable cured product of the polymerizable composition have a multilayer structure in which the polymer composition and the polymerizable composition are alternately repeated. An optical element in which the content of the cured product differs depending on the layer, and the refractive index changes periodically. 2. The optical element according to claim 1, wherein (A) the liquid crystal material contains a trans skeleton or a liquid crystal having a cyano group at a terminal. 3. The polymerizable compound (B) has 5 to 25 carbon atoms.
The optical element according to claim 1, wherein the optical element is a (meth) acrylate having an alkyl group in a side chain. 4. The optical element according to claim 1, wherein (B) the polymerizable compound further contains a monofunctional (meth) acrylate. 5. The layer containing a large amount of a liquid crystal material, wherein the liquid crystal material is covered with a polymer and formed to include an independently existing droplet state.
5. The optical element according to any one of items 4 to 4. 6. The optical element according to claim 1, wherein a distance between a layer mainly composed of a liquid crystal material and a layer mainly composed of a cured polymer is changed for each pixel electrode. 7. Between two transparent substrates having an electrode layer,
(A) 55 to 68% by weight of a liquid crystal material, (B) 30 to 43% by weight of a polymerizable compound, and (C) 2 to 15 of a photopolymerization initiator.
% By weight of the polymerizable composition containing the polymerizable compound by irradiation with interference light. The liquid crystal material and the polymerizable compound have a multilayer structure that repeats alternately, and the content of the liquid crystal material and the polymerizable compound in the alternately formed layers Is a method for producing an optical element in which the refractive index changes periodically depending on the layer.