JP2000347030A - Method for producing cholesteric liquid crystal film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a cholesteric liquid crystalline film of which the diffracted rays themselves produce specified polarized light such as circularly polarized light or linearly polarized light. SOLUTION: The method for manufacturing a cholesteric liquid crystalline film having a region exhibiting diffractiveness on a part of it contains the first step to spread a liquid crystal material on a diffraction pattern surface of a diffraction element substrate, the second step to make the spread liquid crystal material form cholesteric alignment in a liquid crystal state and subsequently to fix the alignment to form a cholesteric liquid crystalline film on the diffraction element substrate, the third step to laminate the surface of the cholesteric liquid crystalline film and a supporting substrate via an adhesive layer and the fourth step to remove the diffraction element substrate from the cholesteric liquid crystalline film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cholesteric liquid crystal film capable of generating diffracted light having a polarizing property.

[0002]

2. Description of the Related Art A diffractive element is a general-purpose optical element that is widely used in the field of spectral optics and the like for the purpose of splitting light and splitting a light beam. Diffraction elements are classified into several types based on their shape.Amplitude type diffraction elements, in which light-transmitting and non-light-transmitting parts are periodically arranged, are phase-type, in which periodic grooves are formed in a highly transparent material. It is usually classified as a diffraction element. Further, they may be classified as a transmission type diffraction element or a reflection type diffraction element according to the direction in which diffracted light is generated.

In the above-described conventional diffraction element, only non-polarized light can be obtained as diffracted light obtained when natural light (non-polarized light) is incident. Polarizing optical instruments such as ellipsometers, which are frequently used in the field of spectroscopy, can only obtain non-polarized light as diffracted light. In general, a method of using diffracted light through a polarizer in order to use only the polarized light component is used.
In this method, there is a problem that about 50% or more of the obtained diffracted light is absorbed by the polarizer, so that the amount of light is reduced by half. For that purpose, it is necessary to prepare a detector having a high sensitivity and a light source having a large amount of light, and the development of a diffraction element in which the diffracted light itself becomes a specific polarized light such as a circularly polarized light or a linearly polarized light has been required.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to control a liquid crystal layer structure by using a diffraction element substrate as an alignment substrate for a liquid crystal material. Succeeded in imparting diffractive power to. More specifically, the present inventors have invented a method for producing a cholesteric liquid crystal film in which a new property of diffractive ability is provided in addition to selective reflection characteristics and circular polarization characteristics unique to cholesteric liquid crystals.

[0005]

That is, the present invention is directed to a first step of developing a liquid crystal material on a diffraction pattern surface of a diffraction element substrate. After forming the developed liquid crystal material in a liquid crystal state, a cholesteric alignment is formed. A second step of forming a cholesteric liquid crystal film on the diffraction element substrate by fixing the cholesteric liquid crystal film, a third step of laminating the cholesteric liquid crystal film surface and the supporting substrate via an adhesive layer, and a diffraction element from the cholesteric liquid crystal film. And a fourth step of removing the substrate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The diffraction element substrate used in the first step of the present invention includes, as its definition, all diffraction elements that generate diffracted light, such as an original flat hologram. In addition, the type may be a diffraction element derived from the surface shape, a so-called film thickness modulation hologram type, a phase element that is not dependent on the surface shape, or the surface shape is converted into a refractive index distribution,
A so-called refractive index modulation hologram type may be used. In the present invention, the type of the film thickness modulation hologram is more preferably used because the diffraction pattern information of the diffraction element can be more easily given to the liquid crystal. In addition, any type of refractive index modulation can be suitably used in the present invention as long as it has undulations that cause diffraction in the surface shape.

The material of the diffraction element substrate is a metal,
It may be a material such as glass or resin, or any material having a diffraction function, such as a material having a diffraction function on the film surface or a thin film having a diffraction function transferred to a film. There may be. Above all, considering ease of handling and mass production,
A film or film laminate having a diffraction function is more desirable. Further, in the diffraction element substrate used in the present invention, the surface on which the liquid crystal material is developed may be subjected to an alignment treatment such as a rubbing treatment.

As the liquid crystal material developed on the diffraction pattern surface of the diffraction element substrate as described above, a polymer liquid crystal, a low molecular liquid crystal, or a mixture thereof can be used. The polymer liquid crystal is not particularly limited as long as the cholesteric alignment can be fixed, and any of a main chain type, a side chain type polymer liquid crystal and the like can be used. Specific examples include main-chain liquid crystal polymers such as polyester, polyamide, polycarbonate, and polyesterimide, and side-chain liquid crystal polymers such as polyacrylate, polymethacrylate, polymalonate, and polysiloxane. Among them, good orientation in forming cholesteric orientation,
A liquid crystalline polyester which is relatively easy to synthesize is desirable. Preferable examples of the constituent units of the polymer include aromatic or aliphatic diol units, aromatic or aliphatic dicarboxylic acid units, and aromatic or aliphatic hydroxycarboxylic acid units.

[0009] Low molecular liquid crystals used as liquid crystal materials include:
For example, calamitic (rod-like) liquid crystals such as biphenyl derivatives, phenylbenzoate derivatives, stilbene derivatives, azobenzene derivatives, pyrimidine derivatives, and cyclohexane derivatives into which functional groups such as acryloyl groups, vinyl groups, and epoxy groups have been introduced, triphenylene derivatives, and torquesen derivatives (A discotic) liquid crystal having a basic skeleton. As the low-molecular liquid crystal, both lyotropic properties and thermotropic properties can be used, but those exhibiting thermotropic properties are more preferable from the viewpoint of workability, process and the like.

In order to improve the heat resistance and the like of the finally obtained cholesteric liquid crystal film, a cross-linking agent such as a bisazide compound or glycidyl methacrylate is used in the liquid crystal material as long as the cholesteric liquid crystal phase is not impaired. The cholesteric liquid crystal phase can be formed in a later step by adding these crosslinking agents. Further, a dichroic dye, a dye, a pigment, or the like can be appropriately added to the liquid crystal material as long as the cholesteric liquid crystal phase is not impaired.

As a method of developing the liquid crystal material, the liquid crystal material is made into a solution or a molten state, and for example, a roll coating method,
By employing a die coating method, a bar coating method, a gravure roll coating method, a spray coating method, a dip coating method, a spin coating method, or the like, it can be developed on a diffraction element substrate.

In the second step of the present invention, the liquid crystal material developed on the diffraction element substrate in the first step is subjected to cholesteric orientation, and the orientation is fixed to form a cholesteric liquid crystal film on the substrate. is there. The formation and fixation of the cholesteric alignment is not particularly limited, and is a known method. For example, when a liquid crystal material mainly including a polymer liquid crystal is used, the liquid crystal material is converted into a liquid crystal state by heat treatment or the like, and the cholesteric liquid crystal phase is formed. And then rapidly cooling from that state to fix the cholesteric orientation. When a liquid crystal material mainly composed of low-molecular liquid crystal is used, the liquid crystal material is converted into a liquid crystal state by heat treatment or the like, and a cholesteric liquid crystal phase is developed, and light, heat or an electron beam is irradiated while maintaining the state. A method of cross-linking liquid crystal molecules to fix cholesteric alignment or the like can be appropriately adopted. Here, the heat treatment temperature cannot be determined unconditionally because it depends on the type and composition of the high- and low-molecular liquid crystal constituting the liquid crystal material, the material of the diffraction element substrate, and the like. Therefore, depending on the liquid crystal material, the diffraction element substrate, etc., the heat treatment temperature,
It is necessary to appropriately set the heat treatment time and the like.

In the third step of the present invention, a step of laminating the cholesteric liquid crystal film formed in the second step on a supporting substrate via an adhesive layer is performed. The support substrate is not particularly limited as long as it has a shape such as a sheet, a film, and a plate.For example, polyimide, polyamideimide, polyamide, polyetherimide, polyetheretherketone, Polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyvinyl chloride, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl alcohol, polyacetal, Sheets, films or substrates of polyarylate, cellulosic plastics, epoxy resin, phenolic resin, etc., or paper, Paper adult paper etc., metal foil, can be appropriately selected from a glass plate or the like. Further, the support substrate may be a substrate having irregularities on its surface.

The adhesive interposed between the cholesteric liquid crystal film and the supporting substrate is not particularly limited, and various conventionally known adhesives and adhesives, for example, a light or electron beam-curable reactive agent can be used. An adhesive, a hot melt adhesive, or the like can be used as appropriate.

As the reactive adhesive, a prepolymer and / or a monomer having photo- or electron-beam polymerizability, if necessary, other monofunctional or polyfunctional monomers, various polymers, a stabilizer, a photopolymerization initiator, What mixed a sensitizer etc. can be used.

Examples of the prepolymer having photo- or electron beam polymerizability include polyester acrylate, polyester methacrylate, polyurethane acrylate, polyurethane methacrylate, epoxy acrylate, epoxy methacrylate, polyol acrylate, polyol methacrylate and the like. . Examples of the monomer having photo- or electron beam polymerizability include monofunctional acrylate, monofunctional methacrylate, difunctional acrylate, difunctional methacrylate, trifunctional or higher polyfunctional acrylate, and polyfunctional methacrylate. These can also use a commercial item, for example, Aronix (acrylic special monomer, oligomer;
Toagosei Co., Ltd.), Light Ester (Kyoeisha Chemical Co., Ltd.),
Viscote (manufactured by Osaka Organic Chemical Industry) or the like can be used.

As the photopolymerization initiator, for example, benzophenone derivatives, acetophenone derivatives, benzoin derivatives, thioxanthones, Michler's ketone, benzyl derivatives, triazine derivatives, acylphosphine oxides, azo compounds and the like can be used. .

The viscosity of the light- or electron-beam-curable reactive adhesive is appropriately selected depending on the processing temperature of the adhesive and the like, and cannot be specified unconditionally.
Pa · s, preferably 50 to 1000 mPa · s, more preferably 100 to 500 mPa · s. Viscosity 1
When it is lower than 0 mPa · s, it becomes difficult to obtain a desired thickness. On the other hand, if it is higher than 2000 mPa · s, the workability may decrease, which is not desirable. When the viscosity is out of the above range, it is preferable to appropriately adjust the solvent and the monomer ratio to obtain a desired viscosity.

When a photocurable reactive adhesive is used, a known curing method such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or a xenon lamp is used as a method for curing the adhesive. be able to. Although the exposure amount cannot be determined unconditionally because it differs depending on the type of the reactive adhesive used, it is usually 50 to 2000 mJ.
/ Cm ² , preferably 100 to 1000 mJ / cm ² .

When an electron beam-curable reactive adhesive is used, the method for curing the adhesive is appropriately selected depending on the penetrating power and the curing power of the electron beam, and cannot be determined unconditionally. Usually, curing can be carried out by irradiating under an acceleration voltage of 50 to 1000 kV, preferably 100 to 500 kV.

When a hot melt type adhesive is used as the adhesive, the adhesive is not particularly limited, but the operating temperature of the hot melt is 80 to 200 ° C., preferably 100 to 200 ° C.
Those having a temperature of about 160 ° C. are desirably used from the viewpoint of workability and the like. Specifically, for example, polyvinyl acetal resins such as ethylene-vinyl acetate copolymer resins, polyester resins, polyurethane resins, polyamide resins, thermoplastic rubbers, polyacrylic resins, polyvinyl alcohol resins, and polyvinyl butyral , Petroleum resin,
Examples include those manufactured using a terpene resin, a rosin resin, or the like as a base resin.

The use of a pressure-sensitive adhesive as an adhesive is not particularly limited. For example, a rubber-based, acrylic, silicone-, or polyvinyl ether-based pressure-sensitive adhesive can be used. Since the thickness of the adhesive varies depending on the application used and its workability, etc., it cannot be said unconditionally,
Usually, it is 0.5 to 50 μm, preferably 1 to 10 μm. The method for forming the adhesive is not particularly limited, but, for example, a roll coating method, a die coating method,
Using a known method such as a bar coating method, a curtain coating method, an extrusion coating method, a gravure roll coating method, a spray coating method, and a spin coating method, a liquid crystal layer or a supporting substrate of a supporting substrate or a cholesteric liquid crystal film and a cholesteric liquid crystal. It can be formed on both liquid crystal layers of the film.

The method of laminating the liquid crystal layer of the cholesteric liquid crystal film and the supporting substrate via an adhesive layer is not particularly limited, but for example, a device having a roll or a pressure plate having a laminating function, and the like. In particular,
Lamination can be performed by appropriately selecting a laminator, a calender roll, a compression molding machine, a rolling mill, or the like.

After the cholesteric liquid crystal film surface is laminated on the support substrate via the adhesive layer as described above,
As a step, the diffraction element substrate used in the first step is removed from the cholesteric liquid crystal film. As a method of removing the diffraction element substrate from the cholesteric liquid crystalline film,
Although there is no particular limitation, for example, a method of peeling and removing the diffraction element substrate or dissolving the diffraction element substrate can be used. As the peeling removal method, for example, a method of sticking an adhesive tape to the corner end of the diffraction element substrate to artificially peel off, a method of mechanically peeling using a roll, etc., after immersing in a poor solvent for all structural materials Mechanical peeling method, method of peeling by applying ultrasonic wave in poor solvent, method of peeling by giving temperature change using difference in thermal expansion coefficient between diffraction element substrate and cholesteric liquid crystal film, diffraction element A method of dissolving and removing the substrate itself or the diffraction pattern layer on the diffraction element substrate can be exemplified. The releasability differs depending on the physical properties of the liquid crystal material forming the cholesteric liquid crystal film and the adhesion to the diffraction element substrate, and therefore, a method most suitable for the system should be adopted.

According to the present invention, the cholesteric liquid crystal having a region exhibiting diffractive power in at least a partial region of the film to which the diffraction pattern of the diffraction element substrate is in contact through the first to fourth steps described above. The conductive film can be obtained on the support substrate via the adhesive layer. Here, the region exhibiting the diffractive power means a region which produces an effect such that the light transmitted through the region or the light reflected by the region wraps around a portion which is geometrically shadow. The presence or absence of a region having diffraction ability is determined by, for example, light (zero-order light) that is incident on a laser beam or the like and is transmitted or reflected linearly.
In addition, it can be confirmed by the presence or absence of light (higher order light) emitted at a certain angle. Alternatively, whether or not the region is formed can be confirmed by observing the surface shape or cross-sectional shape of the liquid crystal layer using an atomic force microscope, a transmission electron microscope, or the like.

In the cholesteric liquid crystal film obtained by the production method of the present invention, the orientation state of the region showing the diffractive ability (the film surface where the diffraction pattern was in contact) is such that the helical axis direction is uniformly parallel to the film thickness direction. It is desirable to form a cholesteric orientation that is not uniform, preferably the helical axis orientation is not uniformly parallel to the film thickness direction and the helical pitch is not evenly spaced in the film thickness direction.
In other regions, a helical structure in which the helical axis orientation is uniformly parallel to the film thickness direction and the helical pitch is uniformly spaced uniformly in the film thickness direction is the same as the normal cholesteric orientation. It is desirable to form.

Further, in the cholesteric liquid crystalline film obtained by the production method of the present invention, when the region exhibiting the diffractive power is formed in a layer state, the thickness of the layer (region) exhibiting the diffractive power is determined by the cholesteric liquid crystalline film. 50% or less, preferably 30%,
Hereinafter, it is more preferable that the layer is formed in a layer state having a thickness of 10% or less. If the thickness of the layer (region) exhibiting the diffractive power exceeds 50%, the effects such as the selective reflection characteristics and the circular polarization characteristics due to the cholesteric liquid crystal phase may be reduced.

In the present invention, after the diffraction element substrate is removed in the fourth step, the fifth step is performed after the removal of the diffraction element substrate for the purpose of protecting the surface of the cholesteric liquid crystal film, increasing the strength, and improving environmental reliability. A protective layer can be formed on the surface of the cholesteric liquid crystalline film. The protective layer is not particularly limited as long as it has an ultraviolet absorbing property and / or a hard coat property. For example, a material in which a protective layer-forming material containing an ultraviolet absorber and a hard coat agent is formed into a film, a sheet, a thin film, or a plate. Further, a protective layer having an ultraviolet absorbing property made of a protective layer forming material containing an ultraviolet absorbent (hereinafter, referred to as an ultraviolet absorbing layer) and a protective layer having a hard coating property made of a protective layer forming material containing a hard coat agent (Hereinafter, a hard coat layer) may be used as a protective layer. In addition, a laminate of a commercially available ultraviolet cut film and a hard coat film can be used as the protective layer. A laminate formed by applying various hard coat agents to the ultraviolet absorbing layer to form a film can also be used as the protective layer. Here, each of the ultraviolet absorbing layer and the hard coat layer may be formed of two or more layers, and each layer can be laminated via an adhesive layer or the like.

As the material for forming the protective layer, a material having high light transmittance is desirable. For example, polyethylene, polypropylene, poly (4-methyl-pentene-1), polystyrene, ionomer, polyvinyl chloride, polymethyl methacrylate, polyethylene terephthalate, polyamide,
A material obtained by adding an ultraviolet absorber and / or a hard coat agent to polysulfone, a cellulose resin, or the like can be used. Further, as the protective layer, an adhesive composition obtained by adding an ultraviolet absorber and / or a hard coat agent to a heat, light or electron beam curing type reactive adhesive can be used, and a cured product of the adhesive composition can be used. Can be used as a protective layer.

The ultraviolet absorber is not particularly limited as long as it is compatible or dispersible in the protective layer forming material. For example, a benzophenone compound, a salicylate compound,
Organic ultraviolet absorbers such as benzotriazole-based compounds, oxalic anilide-based compounds, and cyanoacrylate-based compounds, and inorganic ultraviolet absorbers such as cesium oxide, titanium oxide, and zinc oxide can be used. Among them, a benzophenone-based compound having high ultraviolet absorption efficiency is preferably used. In addition, one or more ultraviolet absorbers can be added. The blending ratio of the ultraviolet absorber in the protective layer varies depending on the material for forming the protective layer to be used.
It is 1 to 20% by weight, preferably 0.5 to 10% by weight.

The hard coat agent is not particularly limited as long as it is compatible or dispersible in the protective layer forming material.
For example, use of an inorganic compound such as an organopolysiloxane-based, photo-curable resin-based acrylic oligomer-based, urethane acrylate-based, epoxy acrylate-based, polyester acrylate-based, thermosetting resin-based acryl-silicone-based, or ceramics. Can be. Above all, an organopolysiloxane-based or photo-curable resin-based acrylic oligomer-based hard coat agent is preferably used from the viewpoint of film-forming properties and the like. These hard coat agents are
Either a solventless type or a solvent type can be used.

The material for forming the protective layer includes, in addition to an ultraviolet absorber and a hard coat agent, if necessary, a light stabilizer such as a hindered amine or a quencher, an antistatic agent, a slipperiness improver, a dye, a pigment, a surfactant. Various additives such as fillers such as fine silica and zirconia can also be blended. The mixing ratio of these various additives is not particularly limited as long as the effects of the present invention are not impaired, but is usually 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

The ultraviolet absorbing layer constituting the protective layer can be formed using a material obtained by appropriately blending the above-described protective layer forming material with an ultraviolet absorbing agent and, if necessary, a light stabilizer. Further, a commercially available ultraviolet cut film or the like can be used as the ultraviolet absorbing layer in the present invention.

The hard coat layer constituting the protective layer is
The protective layer can be formed by using a material in which a hard coat agent and various additives are added to the protective layer forming material described above. The hard coat layer may be formed by applying the above hard coat agent on a transparent support film. As a transparent support film, polymethyl methacrylate, polystyrene, polycarbonate,
Examples include films formed from polyether sulfone, amorphous polyolefin, triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, and the like.

The ultraviolet absorbing layer and the hard coat layer are laminated via an adhesive or the like, and can be used as the protective layer in the present invention. As the adhesive, a heat, light or electron beam curable reactive adhesive or the like can be used. The protective layer can also be formed by using an adhesive containing an ultraviolet absorber and laminating a separately prepared hard coat layer on the cholesteric liquid crystal film. Further, a dye, a pigment, a surfactant and the like may be appropriately added to the adhesive as needed.

Further, as the hard coat layer, a vehicle resin for gravure ink or the like can be preferably used.
Examples of the gravure ink vehicle resin include nitrocellulose, ethylcellulose, polyamide resin, vinyl chloride, chlorinated polyolefin, acrylic resin, polyurethane, and polyester. In addition, hard resins such as ester gum, dammar gum, maleic resin, alkyd resin, phenol resin, ketone resin, xylene resin, terpene resin, petroleum resin, etc. are used in the gravure ink vehicle resin in order to improve adhesion and film strength. May be blended.

The structure of the hard coat layer can be a single hard coat layer or a composite layer depending on the required weather resistance and the like. As the composite layer, for example, a hard coat layer containing an organopolysiloxane, a hard coat layer containing a photocurable resin, a hard coat layer containing a thermosetting resin,
A composite layer composed of two or more layers, such as a hard coat layer containing an inorganic compound, may be used as the hard coat layer.

Further, the degree of the hard coat property, that is, the hardness cannot be unconditionally determined depending on the material constituting the polarization diffraction element. However, when the evaluation is carried out according to the test method described in JIS L0849, at least as a criterion of the discoloration, It is desirable that the number be 3 or more, preferably 4 or more.

The protective layer formed on the cholesteric liquid crystalline film surface from which the diffraction element substrate has been removed, and the ultraviolet absorbing layer and the hard coat layer constituting the protective layer are generally formed by a roll coating method, a dipping method, a gravure coating method, or the like. Known methods such as a method, a bar coating method, a spin coating method, a spray coating method, and a printing method can be employed. After forming a film on a cholesteric liquid crystalline film or a supporting film by these methods, a protective layer can be formed by performing a post-treatment according to the protective layer forming material used. Examples of a method for forming a protective layer composed of a composite layer of an ultraviolet absorbing layer and a hard coat layer include, for example, a method in which a hard coating agent is applied directly to the ultraviolet absorbing layer, a method in which the ultraviolet absorbing layer is laminated via an adhesive, and the like. .

The thickness of the protective layer cannot be unconditionally determined because it depends on the required performance of the ultraviolet absorbing property and the hard coat property, but it is usually 0.1 to 100 μm, preferably 1 to 50 μm. Also, when the protective layer is formed of a composite layer with an ultraviolet absorbing layer and a hard coat layer, the total thickness of each layer is preferably within the above range.

The cholesteric liquid crystalline film obtained by the production method of the present invention has the form 1 (cholesteric liquid crystalline film / adhesive layer / support substrate) obtained through the fourth step, and a protective layer formed on form 1. In the configuration of Embodiment 2 (protective layer / cholesteric liquid crystalline film / adhesive layer / supporting substrate), it can be used as a polarization diffraction element. If the cholesteric liquid crystal film has a certain degree of self-supporting properties, the first and second aspects may be used.
It can be used as a polarization diffraction element in a form in which the support substrate is removed from.

The cholesteric liquid crystalline film obtained by the above-described production method of the present invention has a unique effect that the diffracted light has a circular polarization property, which is not possible with conventional optical members. Due to this effect, it is possible to extremely increase the light use efficiency by using, for example, a spectroscopic optical device that requires polarized light, such as an ellipsometer. Conventional spectroscopic optical devices that require polarized light use a diffraction element such as a diffraction grating or prism to separate the light emitted from the light source for each wavelength and then transmit the light through the polarizer, or transmit the light through the polarizer and then separate the light. It was necessary to have a polarizer. This polarizer has a problem that it absorbs about 50% of the incident light, and has a problem that the light utilization efficiency is extremely poor due to reflection at the interface. However, the cholesteric obtained by the production method of the present invention. The use efficiency of light is extremely high by using a liquid crystal film, and it is theoretically possible to use about 100%. Further, the transmission and blocking of diffracted light can be easily controlled in the cholesteric liquid crystalline film obtained by the production method of the present invention by using a normal polarizing plate. Normally, diffracted light having no polarization cannot be completely blocked by any combination of polarizing plates. That is, in the cholesteric liquid crystal film obtained by the production method of the present invention, for example, a right-polarized diffracted light can be completely blocked only when a left circularly polarizing plate is used, and by using other polarizing plates. Cannot achieve complete shut-off. Because of such an effect, for example, in an environment in which an observer observes a diffraction image through a polarizing plate, by changing the state of the polarizing plate, the diffraction image suddenly emerges from the dark field, or suddenly disappears. It becomes possible.

As described above, the cholesteric liquid crystal film obtained by the production method of the present invention has a very wide range of applications as a new diffractive function element, and various optical elements, optoelectronic elements, decorative members, anti-counterfeiting elements, etc. It can be used as an element or the like.

Specific examples of the optical element and the optoelectronic element include transparent and isotropic films, for example, triacetylcellulose films such as Fujitac (manufactured by Fuji Photo Film) and Konikatac (manufactured by Konica), and TPX films. Polarization diffraction using Arton Film (manufactured by Mitsui Chemicals), Arton Film (manufactured by Nippon Synthetic Rubber Co., Ltd.), ZEONEX Film (manufactured by Nippon Zeon), Acryprene Film (manufactured by Mitsubishi Rayon Co., Ltd.), etc. By obtaining the element (cholesteric liquid crystal film / adhesive layer / support substrate), it is possible to develop it for various optical applications. For example, the polarization diffraction element of the present invention is TN
(Twisted nematic) -LCD (Liq
uid Crystal Display), STN
(Super Twisted Nematic) -L
CD, ECB (Electrically Contro
lled Birefringence)-LCD, O
MI (Optical Mode Interfere)
nce) -LCD, OCB (Optically Co.)
mpensated Birefringence)-
LCD, HAN (Hybrid Aligned Ne)
magnetic) -LCD, IPS (In Plane S)
By providing a liquid crystal display such as a switching-LCD, various LCDs with improved color compensation and / or improved viewing angle can be obtained. Further, the polarization diffraction element can be used as a spectroscopic optical device that requires polarized light separated as described above, a polarization optical element that obtains a specific wavelength by a diffraction phenomenon, an optical filter, a circularly polarizing plate, a light diffusion plate, and the like. In addition, it is possible to provide various optical members that can exhibit an optical effect that has not existed conventionally as an optical element or an optoelectronic element, such as obtaining a linear polarizing plate by combining with a quarter-wave plate. .

As the decorative member, various design molding materials can be obtained, including a new design film having both a rainbow color effect by diffractive power and a colorful color effect by cholesteric liquid crystal. In addition, since it can be made into a thin film, it can be expected to greatly contribute to differentiation from other similar products by a method of attaching it to an existing product or the like or integrating it. For example, by attaching a cholesteric liquid crystal film incorporating a designable diffraction pattern to a glass window or the like, or by using a glass window or the like as a support substrate in the third step, the diffraction pattern accompanies the view angle from the outside. The selective reflection peculiar to the cholesteric liquid crystal looks different colors, and it is excellent in fashionability. Also, the inside is hard to see from the bright outside,
Nevertheless, a window with good external visibility can be provided from the inside.

The anti-counterfeit element can be used as a new anti-counterfeit film, seal, label, etc. having both the anti-counterfeit effect of the diffraction element and the cholesteric liquid crystal. Specifically, as the support substrate in the third step of the present invention, for example, a card substrate such as a car driver's license, an identification card, a passport, a credit card, a prepaid card, various cash vouchers, a gift card, securities, a mount, or the like is used. By doing so, the cholesteric liquid crystal film having a region exhibiting diffractive ability in a part obtained by the production method of the present invention is integrated with or partially provided with a card substrate, a mount, or the like, specifically, affixed, embedded, Can be woven into paper. The cholesteric liquid crystal film obtained by the production method of the present invention has a region exhibiting diffractive ability formed in the cholesteric liquid crystal film, and further has a wavelength-selective reflectivity, a circularly-polarized light selective reflectivity, and a color of the cholesteric liquid crystal. And the effect of exhibiting a beautiful cholesteric color. Therefore, when a cholesteric liquid crystal film having a region exhibiting diffractive ability in a part obtained by the production method of the present invention is used as an anti-counterfeit element, it is difficult to forge the anti-counterfeit element, and more specifically. It can be said that it is extremely difficult to forge a cholesteric liquid crystal film having a region exhibiting diffractive power in the film. In addition to the anti-counterfeiting effect, it also has an iridescent color effect of the diffractive element and a vivid color effect of the cholesteric liquid crystal, and thus has excellent design properties. From these facts, the cholesteric liquid crystal film obtained by the production method of the present invention is very suitable as a forgery prevention element.

These applications are only examples, and a cholesteric liquid crystal film partially having a region exhibiting a diffractive ability obtained by the production method of the present invention has been conventionally used as a diffraction element alone or a fixed cholesteric alignment. Since various applications in which the cholesteric alignment film alone is used, and a new optical effect can be exhibited, it can be applied to various applications other than the above applications.

[0048]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples.

Reference Example 1 Synthesis of Aromatic Liquid Crystalline Polyester 49 mmol of terephthalic acid, 24 m of methylhydroquinone
mol, 25 mmol of catechol, 1.7 mmol of (R) -2-methyl-1,4-butanediol and 100 mg of sodium acetate under a nitrogen atmosphere at 180 ° C.
For 1 hour, at 200 ° C. for 1 hour, and at 250 ° C. for 1 hour to carry out polycondensation while increasing the temperature stepwise. Then, the polycondensation was continued at 250 ° C. for 1 hour while flowing nitrogen, and the polycondensation was further performed at the same temperature under reduced pressure for 1 hour. After dissolving the obtained polymer in tetrachloroethane, reprecipitation was performed with methanol to obtain a purified polymer (aromatic liquid crystal polyester).

The logarithmic viscosity of the obtained polymer is 0.144.
dl / g (measured in a phenol / tetrachloroethane = 60/40 (weight ratio) solvent at a concentration of 0.5 g / 100 ml at 30 ° C. using a Ubbelohde viscometer) and a glass transition point of 85 ° C. (PERKIN- ELMERDSC 7).

Example 1 A blazed diffraction grating (AJ41025: Edmund Scientific) obtained by rubbing an N-methyl-2-pyrrolidone solution (20% by weight) of the aromatic liquid crystal polyester obtained in Reference Example 1 with a nylon cloth. (Tific Japan Co., Ltd. product), spin-coated, dried on a hot plate at 60 ° C. for 20 minutes, and then heat-treated at 200 ° C. for 10 minutes. The surface has a golden mirror-reflective film. A diffraction grating was obtained.

Then, a commercially available acrylic photo-curing adhesive was applied on the surface exhibiting the golden reflection with a bar coater to a thickness of 5 μm.
m, and then a triacetyl cellulose film is laminated thereon by a laminator, cured by irradiating with ultraviolet light, and then a blazed diffraction grating and a film exhibiting golden reflection (a layer of aromatic liquid crystal polyester). To obtain a laminate having a cholesteric liquid crystalline film.

In the obtained laminate, iridescent color caused by the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal were clearly recognized. When the transmission spectrum of the laminated body was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, it showed selective reflection with a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm. I understand. Furthermore, when the alignment state of the liquid crystal layer portion of the laminate was observed with a polarizing microscope and the cross section of the liquid crystal layer was observed with a transmission electron microscope, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction, and the helical pitch was It was confirmed that cholesteric alignments not uniformly spaced in the film thickness direction were formed in the surface region of the liquid crystal layer.

Then, on the liquid crystal layer side surface of the obtained laminate, lipoxy SP-1509 (trade name, manufactured by Showa Polymer Co., Ltd.) and fine silica (Aerosil R812, trade name, manufactured by Nippon Aerosil Co., Ltd.) 5% by weight, UV absorber Cya
A 20% by weight solution of isopropyl alcohol mixed with 5% by weight of sorbUV-24 (manufactured by Scitech) and 4% by weight of lucirin TPO (trade name of BASF) was applied by a bar coater to a thickness of 5 μm and dried. A polyethylene terephthalate film with a silicone release layer is bonded to the application surface using a desktop laminator, irradiated with ultraviolet light, and the adhesive is cured. After holding the edge of the polyethylene terephthalate film by hand, the cholesteric liquid crystal layer is oriented in the 180 ° direction. And a cholesteric liquid crystal film having a protective layer on the surface was obtained. Also in this film, iridescence caused by the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal were clearly recognized, and no change was observed in the state before the formation of the protective layer.

(Reference Example 2) Synthesis of acryloyl group-bonded liquid crystal compound (1) To 180 g of distilled and purified tetrahydrofuran was added 4- (6).
-Acryloyloxyhexyloxy) benzoic acid 151.
3 g (518 mmol) and 1.5 g of 2,6-ditert-butyl-4-methylphenol were dissolved in 70.1 g (543 mmol) of diisopropylethylamine.
l) was added to methanesulfonyl chloride.
A solution of 1 g (543 mmol) in tetrahydrofuran was added dropwise over 30 minutes with stirring while cooling to -10 ° C. After completion of the dropwise addition, the temperature of the reaction solution was raised to 0 ° C., and the mixture was further stirred for 15 minutes.
(246 mmol) in tetrahydrofuran was added dropwise. Thereafter, the reaction solution was stirred for 15 minutes, and then a solution of 3.0 g (25 mmol) of 4-dimethylaminopyridine dissolved in 62.4 g (617 mmol) of triethylamine was added dropwise. After the dropwise addition, the reaction solution was stirred at 0 ° C. for 1 hour, further heated to room temperature, and reacted under stirring for 5 hours. After the completion of the reaction, the reaction solution was diluted with 1000 ml of ethyl acetate, extracted, dehydrated, dried, and concentrated by a rotary evaporator to give methylhydroquinone bis (4- (6-acryloyloxyoxyhexyloxy) benzoate) ester as a crude product. Obtained as a product. The crude product was recrystallized from ethyl acetate / methanol to give 146.9 g of methylhydroquinone bis (4- (6-acryloyloxyoxyhexyloxy) benzoic acid) ester (acryloyl group-bonded liquid crystal compound (1)) as white crystals. (Yield 8
5.2%). The compound (1) had a purity of 9 by GPC.
It was 8.7%. GPC uses tetrahydrofuran as an elution solvent, and is a packed column for high-speed GPC (TSKge).
l GPC analyzer CCP & 8000 (CP-8000, CO-80) manufactured by Tosoh equipped with G-1000HXL
00, UV-8000). When the compound (1) is observed on a hot stage under a polarizing microscope,
Transforms into a crystalline phase at room temperature, a nematic phase around 85 ° C,
When it was further heated, it became an isotropic phase at around 115 ° C.

Reference Example 3 Synthesis of Acryloyl Group-Binding Compound (2) Using the same method as in Reference Example 2, 32.5 g of 4- (6-acryloyloxyoxyhexyloxy) benzoic acid (111 m
mol), 12.6 g of 4-cyanophenol (106 m
mol) to 34.8 g of 4-cyanophenol 4-
(6-Acryloyloxyhexyloxy) benzoic acid ester (acryloyl group-binding compound (2), yield: 84
%). The compound (2) had a purity of 9 by GPC.
It was 9.3%.

(Example 2) 7.0 g of the acryloyl group-bonded liquid crystal compound (1) obtained in Reference Example 2 described above, 1.07 g of the acryloyl group-bonded compound (2) obtained in Reference Example 3, and the chiral dopant liquid crystal S -811 (Rodick)
1.93 g was dissolved in 90 g of N-methyl-2-pyrrolidone. In addition, a transmission type diffraction grating film (AJ40267: Edmond) in which a solution containing 1.5 mg of a fluorosurfactant S-383 (produced by Asahi Glass Co., Ltd.) was attached to a 1 mm thick glass plate and the surface was rubbed with a nylon cloth. (Scientific Japan Co., Ltd. product) using a bar coater, put into a clean oven set at 60 ° C., dry for 20 minutes, and then heat-treat in an oven set at 80 ° C. for 10 minutes Then, the cholesteric alignment of the liquid crystal layer was completed by cooling from that temperature to 50 ° C. at about 1 ° C./min.

After the heat treatment, the diffraction grating film coated with the liquid crystal layer was taken out of the oven, cooled to room temperature, and irradiated with an electron beam (EB) at room temperature. The EB irradiation was performed using an EB irradiation apparatus manufactured by Eye Electron Beam, at room temperature, in an atmosphere with an oxygen concentration of 0.10%, and at an acceleration voltage of 3
Irradiation was performed at 0 kV. The liquid crystal layer after the irradiation was hardened, and the surface hardness was about H to 2H in terms of pencil hardness. Also, cut a part of the film from the glass plate,
Ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation
As a result of measuring the transmission spectrum, there was a transmitted light reduction region derived from selective reflection at about 680 nm.

Next, Aronix UV-3630 (product of Toagosei Co., Ltd.) which is a UV-curable adhesive is applied to the liquid crystal layer surface.
Was applied, a triacetyl cellulose film was laminated on the application surface using a small laminator, and cured by irradiation with ultraviolet light. After removing the glass plate to which the diffraction grating film was attached, the diffraction grating film was gently peeled in the 180 ° direction from the cholesteric-aligned liquid crystal layer surface to obtain a cholesteric liquid crystal film laminate.

In the obtained laminate, the iridescent color resulting from the diffraction pattern and the selective reflection characteristic of the cholesteric liquid crystal were clearly recognized. When the orientation state of the cholesteric liquid crystal layer was observed with a polarizing microscope and the cross section of the liquid crystal layer was observed with a transmission electron microscope, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction, and the helical pitch was not uniform in the film thickness direction. It was confirmed that cholesteric alignments that were not uniformly spaced were formed in the surface region of the liquid crystal layer. Also, a He-Ne laser (wavelength 632.
8 nm), a laser beam was observed at an emission angle of 0 ° and about ± 36 °. In order to further confirm the polarization characteristics, the obtained laminate was placed under normal room illumination and observed through a left circularly polarizing plate (transmitting only left circularly polarized light). And the brightness when observed without a polarizing plate was almost the same. In contrast, observation through a right circularly polarizing plate (transmitting only right circularly polarized light) resulted in a dark field, and no rainbow-colored reflected diffracted light was observed. From the above, it was found that the obtained laminate had a function as a polarization diffraction element.

[0061]

According to the manufacturing method of the present invention, a diffractive element substrate is used as an alignment substrate for a liquid crystal material, so that a part of a cholesteric liquid crystalline film obtained by aligning and fixing the cholesteric liquid crystal material has a diffractive ability. The indicated area can be formed. Further, the cholesteric liquid crystal film obtained by the production method of the present invention has both the optical characteristics of the diffraction element and the cholesteric liquid crystal layer in which the diffracted light has circular polarization, and is unique to the conventional optical element. It has optical characteristics. Because of having such optical properties, the cholesteric liquid crystal film has a very wide range of application as a polarization diffraction element. For example, an optical element such as a liquid crystal display, an optoelectronic element, a decoration material, and an optical element such as a forgery prevention element. It can be suitably used as a member.

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Claims (3)

[Claims] 1. A first step of developing a liquid crystal material on a diffraction pattern surface of a diffraction element substrate, forming a cholesteric alignment of the developed liquid crystal material in a liquid crystal state, fixing the alignment, and forming the cholesteric alignment on the diffraction element substrate. A second step of forming a cholesteric liquid crystal film, and a third step of laminating the cholesteric liquid crystal film surface and the support substrate via an adhesive layer.
A method for producing a cholesteric liquid crystal film partially including a region exhibiting diffractive power, comprising a step and a fourth step of removing the diffraction element substrate from the cholesteric liquid crystal film. 2. A cholesteric liquid crystalline film produced by the method according to claim 1. 3. A polarization diffraction element comprising at least a cholesteric liquid crystalline film produced by the method according to claim 1.