JP2000309642A - Cholesteric liquid crystalline film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new liquid crystalline film providing a diffracted light capable of producing specific polarized light such as circularly polarized light or linearly polarized light. SOLUTION: This cholesteric liquid crystalline film is formed of a film material consisting of a high molecular weight liquid crystal, as essential component, having 1,000-100,000 weight-average molecular weight Mw measured by a gel permeation chromatography [GPC (expressed in terms of polystyrene)], <=5 molecular weight distribution (Mw/Mn; Mn is the number-average molecular weight), 0.05-2.0 logarithmic viscosity at 0.5 g/dL concentration (at 30 deg.C) in a mixed solvent of [phenol/tetrachloroethane (60/40 weight ratio)], <=200 deg.C glass transition temperature (Tg) and >=40 deg.C transition temperature (Ti) from the liquid phase to the isotropic phase. The cholesteric liquid crystalline film has a region exhibiting the diffraction ability and formed in a part of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel cholesteric liquid crystal film capable of generating diffracted light having a polarization 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 a polymer liquid crystal having specific physical properties is used as a film material so that at least a part of the film has a diffractive ability. We succeeded in forming a region with the cholesteric liquid crystal film and developed a new cholesteric liquid crystal film. More specifically, the present inventors have invented a cholesteric liquid crystal film having a new property of diffractive ability in addition to selective reflection characteristics and circular polarization characteristics unique to cholesteric liquid crystals.

[0005]

That is, the present invention provides a GP
Weight average molecular weight Mw measured in C (polystyrene conversion)
Is 1000 to 100,000, the molecular weight distribution (Mw / Mn; Mn is the number average molecular weight) is 5 or less, and the logarithmic viscosity is 0.05 to 2.0.
(Phenol / tetrachloroethane (weight ratio 60/4)
0) Concentration of 0.5 g / dl (temperature 30
C)), a film formed of a film material containing a polymer liquid crystal having a glass transition temperature (Tg) of 200 ° C or lower and a transition temperature (Ti) from a liquid crystal phase to an isotropic phase of 40 ° C or higher as an essential component. The present invention relates to a cholesteric liquid crystal film in which a region exhibiting diffractive ability is formed in a part of the film.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The cholesteric liquid crystal film of the present invention has a GP
Weight average molecular weight Mw measured in C (polystyrene conversion)
Is 1000 to 100,000, the molecular weight distribution (Mw / Mn; Mn is the number average molecular weight) is 5 or less, and the logarithmic viscosity is 0.05 to 2.0.
(Phenol / tetrachloroethane (weight ratio 60/4)
0) Concentration of 0.5 g / dl (temperature 30
° C)), having a glass transition temperature (Tg) of 200 ° C or lower and a transition temperature (Ti) from a liquid crystal phase to an isotropic phase of 40 ° C or higher, and being formed from a film material containing a polymer liquid crystal as an essential component. Things.

GPC of polymer liquid crystal (polystyrene conversion)
If the weight-average molecular weight (Mw) measured in (1) is less than 1,000, the resulting liquid crystalline film has low mechanical strength, which is not desirable in various post-treatment steps and practical performance. If it exceeds 100,000, the fluidity of the liquid crystal deteriorates, which may adversely affect the alignment. On the other hand, if the molecular weight distribution exceeds 5, the meltability at the time of producing a cholesteric liquid crystalline film and the solubility in a solution become poor, and uniform orientation to a cholesteric phase is difficult to obtain, which may cause a practical problem. The logarithmic viscosity is 0.05
If it is less than 10, the mechanical strength of the cholesteric liquid crystalline film may be low, which is not desirable in various post-processes and practical performance. On the other hand, if it exceeds 2.0, the fluidity of the liquid crystal deteriorates, and it may be difficult to obtain a uniform alignment to the cholesteric phase. Further, when the glass transition temperature (Tg) is higher than 200 ° C., the fluidity in the liquid crystal state is poor, and it may be difficult to obtain uniform alignment. Further, if necessary, it is difficult to select a support substrate used for alignment. May also occur. Further, the transition temperature (Ti) from the liquid crystal phase to the isotropic phase is 4
If the temperature is lower than 0 ° C., the alignment stability of the cholesteric liquid crystal film at around room temperature may be undesirably deteriorated.

[0008] The polymer liquid crystal used in the present invention is not particularly limited as long as it satisfies the above-mentioned various physical properties, and any of a main chain type and a side chain type polymer liquid crystal may be used. Can be. 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, a liquid crystalline polyester which has good orientation in forming cholesteric orientation and is relatively easy to synthesize is desirable. Preferred examples of the constituent unit of the polymer include an aromatic or aliphatic diol unit, an aromatic or aliphatic dicarboxylic acid unit, and an aromatic or aliphatic hydroxycarboxylic acid unit.

In order to improve the heat resistance and the like of the finally obtained cholesteric liquid crystalline film, a crosslinking agent such as a bisazide compound or glycidyl methacrylate is added to the film material as long as the cholesteric phase is not impaired. Alternatively, by adding these crosslinking agents, crosslinking can be performed in a state where a cholesteric phase is developed. Furthermore, in the film material,
Various additives such as dichroic dyes, dyes, and pigments can be appropriately added as long as the effects of the present invention are not impaired.

The cholesteric liquid crystal film of the present invention is a film formed from a film material containing a polymer liquid crystal as an essential component as described above, and a region having diffractive ability is formed in a partial region of the film. Things. The method of forming the region exhibiting diffractive power is, for example, after forming a uniform cholesteric alignment film using a film material,
There is a method of transferring a mold having a desired diffraction pattern to a cholesteric alignment film.

The cholesteric alignment film before the transfer of the diffraction pattern is, for example, by applying the above-mentioned film material on a support substrate or an alignment film formed on the substrate,
It can be obtained by heat treatment.

The support substrate used for obtaining the cholesteric alignment film is not particularly limited as long as it does not inhibit cholesteric alignment, and examples thereof include a glass substrate or a plastic substrate such as a plastic film or a plastic sheet. . As the glass substrate, for example, soda glass, silica-coated soda glass, borosilicate glass substrate, or the like can be used. As the plastic substrate, a polymethyl methacrylate, polystyrene, polycarbonate, polyether sulfone, polyphenylene sulfide, amorphous polyolefin, triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate substrate, or the like can be used. A uniaxial or biaxial stretching operation can be appropriately applied to these supporting substrates as needed. Further, the substrate may be subjected to a surface treatment such as a hydrophilization treatment, a hydrophobization treatment, and an easy peeling treatment. As the support substrate, one type alone or a laminate of two or more types of substrates can be used as the support substrate.

As the alignment film, a rubbed polyimide film is preferably used, but other alignment films known in the art can also be used as appropriate. Also, a plastic substrate or the like obtained by directly imparting an orientation ability by a rubbing treatment without applying polyimide or the like can be used when obtaining a cholesteric orientation film. The method of the alignment treatment is not particularly limited, but any method may be used as long as the liquid crystal molecules are uniformly aligned in parallel with the alignment treatment interface. Next, as a means for applying a film material on the alignment film, there are a melt coating and a solution coating.

In the solution application, a film material is dissolved in a solvent at a predetermined ratio to prepare a solution having a predetermined concentration. As the solvent, although it varies depending on the type of film material to be used, usually, hydrocarbons such as toluene, xylene, butylbenzene, tetrahydronaphthalene, and decahydronaphthalene, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, ether such as tetrahydrofuran, Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl lactate, γ
-Esters such as butyrolactone, amides such as N-methyl-2-pyrrolidone, dimethylformamide and dimethylacetamide, halogenated hydrocarbons such as dichloromethane, carbon tetrachloride, tetrachloroethane and chlorobenzene, butyl alcohol, triethylene glycol, Alcohols such as diacetone alcohol and hexylene glycol can be used. If necessary, two or more of these solvents can be used as a mixture. The concentration of the solution depends on the molecular weight and solubility of the polymer liquid crystal used,
Further, since it depends on the final film thickness of the target film and the like, it cannot be said unconditionally, but it is usually 1 to 60% by weight, preferably 3 to 40% by weight.

Further, a surfactant or the like may be added to the solution to facilitate application. Examples of the surfactant include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides, and polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, primary and secondary alcohol ethoxylates. , Alkylphenol ethoxylates, polyethylene glycols and esters thereof, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, etc. Surfactants, amphoteric surfactants such as lauryl amide propyl betaine and lauryl amino acetate betaine, and nonionic surfactants such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine , Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group-containing oligomer Fluorinated surfactants such as fluoroalkyl group-containing urethanes and the like are included. The amount of the surfactant to be added depends on the type of the surfactant, the solvent, and the supporting substrate to be coated.
The range is 0 ppm to 10%, preferably 50 ppm to 5%, and more preferably 0.01% to 1%.

The film material solution prepared as described above is applied on an alignment film or a substrate which has been subjected to an alignment process such as a rubbing process.

As a coating method, for example, a roll coating method, 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 and the like can be adopted.

After the application, the solvent is removed by drying, and a heat treatment is performed at a predetermined temperature and for a predetermined time to exhibit a cholesteric liquid crystal phase, thereby completing cholesteric alignment. Next, the cholesteric alignment film formed in the liquid crystal state is rapidly cooled to a temperature equal to or lower than the glass transition point of the polymer liquid crystal, whereby a cholesteric alignment film in which the cholesteric alignment is fixed can be obtained. The thickness of the cholesteric alignment film is not particularly limited, but is usually 0.3 to 20 μm, preferably 0.1 to 20 μm from the viewpoint of mass productivity and a manufacturing process.
It is desirable that it is 5 to 10 μm, more preferably 0.7 to 3 μm.

The cholesteric liquid crystal film of the present invention can be obtained by transferring the diffraction pattern of the diffraction element substrate onto the cholesteric alignment film obtained as described above. The material of the diffraction element substrate used for the transfer of the diffraction pattern may be a material such as metal or resin, or a material having a diffraction function on the film surface, or a thin film having a diffraction function transferred to a film. Any material may be used as long as it has a diffraction function. Above all, in view of ease of handling and mass productivity, a film or a film laminate having a diffraction function is more desirable.

The term "diffraction element" as used herein includes, as its definition, all diffraction elements that generate diffracted light, such as an original flat hologram. The type may be a diffraction element derived from the surface shape, a so-called film thickness modulation hologram type, or a phase element independent of the surface shape or a surface shape converted into a refractive index distribution, a so-called refraction. A rate 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.

As a method of transferring a diffraction pattern, for example, generally used heat rollers, laminators,
Using a hot stamp, an electric heating plate, a thermal head, or the like, it can be performed under pressure and heating conditions. The conditions of pressurization and heating differ depending on the physical properties of the polymer liquid crystal and low-molecular liquid crystal to be used, the type of the diffraction element substrate, and the like, and cannot be unconditionally determined, but are usually 0.01 to 100 MPa, preferably 0.1 to 100 MPa. It is appropriately selected depending on the type of liquid crystal, substrate and the like used in the range of 0.05 to 80 MPa and the temperature of 30 to 400 ° C, preferably 40 to 300 ° C.

In the cholesteric liquid crystalline film of the present invention, a region exhibiting diffractive ability can be formed in a part of the film by transferring a diffraction pattern to a cholesteric alignment film. Here, the region exhibiting diffractive power is:
It means a region in which light transmitted through the region or reflected by the region produces an effect of wrapping around a shadowed portion geometrically. The presence or absence of a region having a diffractive ability is confirmed by, for example, the presence or absence of light (higher-order light) emitted at a certain angle other than light (0th-order light) that enters a laser beam or the like into the aforementioned region and transmits or reflects linearly. can do. Alternatively, by observing the surface shape or cross-sectional shape of the liquid crystal layer with an atomic force microscope, a transmission electron microscope, or the like, it can be confirmed whether or not a region having a diffractive ability is formed. The region exhibiting the diffractive power may be any region on the film surface and / or inside the film. For example, the region is formed on a part of the film surface (film surface region) or a part of the film inside (film internal region). be able to. In addition, the region may be formed in a plurality of regions of the cholesteric liquid crystal film, for example, a film front and back surface region and a plurality of film internal regions. In the present invention, the term "film surface" means a portion of the cholesteric liquid crystal film alone that contacts the outside, and the term "inside of the film" means a portion other than contacting the outside.

The region exhibiting diffractive power formed on a part of the cholesteric liquid crystal film of the present invention is not necessarily formed, for example, as a layer having a uniform thickness on the film surface or inside. Instead, it is only necessary that a region exhibiting diffractive power is formed on at least a part of the film surface or inside the film. For example, the region having the diffraction power may have a shape such as a desired figure, pictogram, or numeral. Further, when having a plurality of regions exhibiting diffractive power, it is not necessary that all the regions exhibit the same diffractive power,
Each region may show a different diffraction power.

When the region exhibiting diffractive ability is formed in a layer state, the thickness of the layer (region) exhibiting diffractive ability is usually 50% or less, preferably 30% or less, of the film thickness of the cholesteric liquid crystal film. %, More preferably 10% or less. When the thickness of the layer (region) exhibiting the diffractive ability exceeds 50%, the effects of the present invention such as selective reflection characteristics and circular polarization characteristics due to the cholesteric liquid crystal phase are reduced, and the effect of the present invention may not be obtained. .

Further, the orientation state of the region exhibiting the diffractive power in the cholesteric liquid crystalline film is such that the helical axis direction is not uniformly parallel to the film thickness direction, preferably the helical axis direction is uniformly parallel to the film thickness direction. In addition, it is desirable to form a cholesteric orientation in which the helical pitch is not uniformly 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.

In the cholesteric liquid crystal film of the present invention, when a region exhibiting a diffractive power is present on one film surface region, the film surface having the diffractive power is opposite to the film surface having the diffractive power. It shows an optical effect, a coloring effect and the like slightly different from those of the surface. Therefore, it is desirable to select an arrangement position and the like of the film surface of the cholesteric liquid crystal film of the present invention according to the use and the intended function.

The thus obtained cholesteric liquid crystalline film of the present invention may be transferred from a support substrate used for forming a cholesteric alignment film to another substrate, if necessary. Examples of the transfer method include a method of applying an adhesive or the like to a cholesteric liquid crystal film, laminating another substrate, curing the adhesive, and separating the supporting substrate from the cholesteric liquid crystal film. By appropriately employing this transfer method, it is possible to obtain a form suitable for various uses, for example, an optical laminate in which various support substrates, an adhesive layer, and a cholesteric liquid crystal film are laminated in this order. Depending on the application, the film surface on which the diffraction pattern of the cholesteric liquid crystalline film is transferred or the opposite film surface can be appropriately selected, for example, by laminating the film surface on a support substrate via an adhesive layer.

The support substrate used for the transfer 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, polyether Imide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyvinyl chloride, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, Sheets and filters of polycarbonate, polyvinyl alcohol, polyacetal, polyarylate, cellulosic plastics, epoxy resin, phenolic resin, etc. Beam or the substrate or paper, paper such as synthetic paper, 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 used at the time of transfer is not particularly limited, and various hitherto-known adhesives, hot melt adhesives, heat, light or electron beam-curable adhesives can be used. An adhesive or the like can be used as appropriate. Among them, a light or electron beam curing type reactive adhesive is preferably used.

Examples of the reactive adhesive include 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.

Specific 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.), Biscoat (Osaka Organic Chemical Industry Co., Ltd.)
Etc. 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 cannot be unconditionally determined.
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 of 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 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, and examples thereof include a roll coating method, a die coating method, a bar coating method, a curtain coating method, an extrusion coating method, a gravure roll coating method, and a spray coating method. It can be formed on a supporting substrate or the like using a known method such as a spin coating method or a spin coating method.

In the cholesteric liquid crystal film of the present invention, a protective layer can be provided on the film surface in order to improve abrasion resistance and light resistance. As the protective layer,
A single hard coat layer may be provided, or a laminate composed of two or more layers, such as providing various polymer films or a hard coat layer via an adhesive layer, may be used as the protective layer. As the hard coat layer, a cured product of the reactive adhesive described above, a vehicle resin for gravure ink, or the like can be preferably used.

Examples of the vehicle resin for gravure ink used as the protective layer include nitrocellulose, ethylcellulose, polyamide resin, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, chloride rubber, cyclized rubber, chlorinated polyolefin, and acrylic resin. , Polyurethane, polyester and the like. Further, a hard resin such as an ester gum, a dammar gum, a maleic acid resin, an alkyd resin, a phenol resin, a ketone resin, a xylene resin, a terpene resin, and a petroleum resin may be added to the resin to improve adhesiveness and film strength. .

As the polymer film used as the protective layer, for example, polyethylene, polypropylene,
Films such as poly (4-methyl-pentene-1), polystyrene, ionomer, polyvinyl chloride, polymethyl methacrylate, polyethylene terephthalate, polyamide, polysulfone, siloxane-based resin, epoxy-based resin, and cellulose-based resin are exemplified.

The adhesive for forming the protective layer is not particularly limited, but the above-described cured reactive adhesive can be used. If necessary,
The hard coat layer, the adhesive layer, and the polymer film that constitute the protective layer appropriately contain various additives, such as an ultraviolet absorber, a dye, a pigment, a surfactant, fine silica, zirconia, and alumina, and a filler. Can also.

As described above, the cholesteric liquid crystal film 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 of extremely low light utilization efficiency due to reflection at the interface. However, the polarizer uses the cholesteric liquid crystal film of the present invention. As a result, the light use efficiency is extremely high, and it is theoretically possible to use about 100%. The cholesteric liquid crystal film of the present invention can easily control transmission and blocking of diffracted light 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 of the present invention, for example, diffracted light having a right polarization property can be completely blocked only when a left circularly polarizing plate is used, and completely blocked even when other polarizing plates are used. It cannot be realized. 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 of the present invention has a very wide range of application as a new diffraction function element, and is used as various optical elements, optoelectronic elements, decorative members, forgery prevention elements and the like. be able to.

Specific examples of the optical element and the optoelectronic element include a cholesteric liquid crystal film of the present invention alone or a transparent and isotropic film as a support substrate, for example, Fujitac (Fuji Photo Film Co., Ltd.)
Triacetylcellulose film such as Konica Catac (Konica Corporation), TPX film (Mitsui Chemicals Co., Ltd.), Arton film (Nippon Synthetic Rubber Co., Ltd.)
ZEONEX Film (Zeon Corporation),
An optical laminate in which a cholesteric liquid crystal film is laminated on an acrylene film (manufactured by Mitsubishi Rayon Co., Ltd.) or the like
N (twisted nematic) -LCD (Li
(Quid Crystal Display), STN
(Super Twisted Nematic) -L
CD, ECB (Electrically Contr
old Birefringence) -LCD,
OMI (Optical Mode Interferer)
ence) -LCD, OCB (Optically C)
Ompensated Birefringence)
-LCD, HAN (Hybrid Aligned N)
ematic) -LCD, IPS (In Plane)
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, a cholesteric liquid crystal film or an optical laminate having the film, as described above, a spectroscopic optical device that requires polarized light, a polarizing optical element that obtains a specific wavelength by a diffraction phenomenon, an optical filter, a circularly polarizing plate, It can be used as a light diffusing plate, etc., and can be used in combination with a quarter-wave plate to obtain a linear polarizing plate. Optical member can be provided.

As the decorative member, various design molding materials can be obtained, including a new design film having a rainbow-coloring effect by diffractive power and a vivid coloration 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, when the cholesteric liquid crystal film of the present invention incorporating a diffractive pattern having a design property is attached to a glass window or the like, the selective reflection specific to the cholesteric liquid crystal accompanied by the diffraction pattern becomes different from the outside depending on the viewing angle. It looks good and becomes fashionable. In addition, it is possible to provide a window in which the inside is hardly seen from the bright outside, and the outside is excellent in the interior 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, the cholesteric liquid crystal film of the present invention is integrated with, 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, and securities, a mount, and the like. Alternatively, it can be provided in part, specifically, pasted, embedded, or woven into paper. Further, the cholesteric liquid crystal film of the present invention has a region exhibiting diffractive ability in a part of the cholesteric liquid crystal layer,
In addition, the cholesteric liquid crystal also has the wavelength-selective reflectivity, the circularly-polarized light selective reflectivity, the viewing angle dependence of the color, and the effect of exhibiting a beautiful cholesteric color. Therefore, it can be said that it is extremely difficult to forge a cholesteric liquid crystal film partially having a diffraction ability, like the cholesteric liquid crystal film of the present invention. 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 of the present invention is very useful as a device for preventing forgery.

These applications are only examples, and the cholesteric liquid crystal film of the present invention can be used in various applications where a single diffraction element or a single cholesteric liquid crystal film is conventionally used, or a new optical effect is exhibited. Therefore, it can be applied to various uses other than the above.

[0049]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. Various measurement methods used in the present invention will be described. (GPC measurement method) Tosoh GPC (CP8000, CO
8000, UV8000), TSKG3000HX
L, G2000HXL and G1000HXL were connected, and tetrahydrofuran (THF) was added at 25 ° C.
The measurement was performed with a solvent at a flow rate of 0.7 ml / min. A calibration curve was separately prepared using standard polystyrene under the same conditions, and the weight average molecular weight Mw, number average molecular weight Mn, and molecular weight distribution Mw / Mn in terms of polystyrene were determined. (Measurement of glass transition temperature (Tg)) D manufactured by Du Pont
It was measured by SC990. (Measurement of transition temperature (Ti) from liquid crystal phase to isotropic phase) Polarizing microscope B manufactured by Olympus Corporation equipped with a hot stage
The measurement was performed at X50.

(Example 1) Mw is 3000, Mw / Mn
A film was formed by a spin coating method on a rubbed polyphenylene sulfide film of a liquid crystalline polyester (containing an R-form optically active compound) having a 2.0, logarithmic viscosity of 0.124, Tg of 80 ° C, and Ti of 230 ° C.

Next, when heat-treated at 180 ° C. for 5 minutes,
A film exhibiting a golden specular reflection was obtained. When a transmission spectrum of the obtained film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the center wavelength was about 600 nm and the selective reflection wavelength bandwidth was about 100 n.
It was confirmed that a cholesteric alignment film in which cholesteric alignment showing selective reflection of m was fixed was obtained.

Next, a scored diffraction grating film (900 / m) manufactured by Edmund Scientific Japan
m), so that the diffraction surface and the liquid crystal surface of the cholesteric alignment film face each other, and using a laminator DX-350 manufactured by Tokyo Laminex Co., Ltd., heat-presses at 120 ° C., 0.3 MPa and a roll contact time of 0.5 second. went. After cooling to room temperature, the diffraction grating film was removed.

Observation of the cholesteric alignment film surface on which the diffraction grating film was superimposed revealed clear iridescence caused by the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal. Also, when the orientation state of the cholesteric alignment film surface from which the diffraction grating film was removed was observed by a polarizing microscope and a transmission electron microscope of the liquid crystal layer cross section, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction. It was also confirmed that cholesteric alignment in which the helical pitch was not uniformly spaced in the film thickness direction was formed in the surface region of the liquid crystal layer. In other regions, it was confirmed that a cholesteric orientation in which the helical axis orientation was uniformly parallel to the film thickness direction and the helical pitch was uniformly uniform in the film thickness direction was formed.
In addition, He-N
When an e-laser (wavelength 632.8 nm) is incident,
Laser light was observed at emission angles of 0 ° and about ± 35 °. In order to further confirm the polarization characteristics, the obtained laminate was placed under normal room illumination and observed through a right circularly polarizing plate (transmitting only right circularly polarized light). And the brightness when observed without a polarizing plate was almost the same. On the other hand, a left circularly polarizing plate (only left circularly polarized light is transmitted)
Observed through the above, a dark field was obtained, and no iridescent reflected and diffracted light was observed.

From these results, it was confirmed that in the cholesteric alignment film, a region exhibiting diffractive ability was formed in the film surface region, and that the diffracted light was right-handed circularly polarized light. From this, it was found that the cholesteric liquid crystal film of the present invention was obtained by transferring the diffraction pattern of the diffraction grating film to the cholesteric alignment film.

(Example 2) Mw is 7000, Mw / Mn
A film was formed by spin coating on polyphenylene sulfide rubbed with a liquid crystalline polyester (containing an R-form optically active compound) having a 2.0, logarithmic viscosity of 0.144, Tg of 85 ° C and Ti of 230 ° C. Then, when the film was heat-treated at 200 ° C. for 5 minutes, a film having a golden specular reflection was obtained.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that a film in which the cholesteric orientation shown was fixed was formed.

The laminator manufactured by Tokyo Laminex Co., Ltd. was overlapped so that the diffraction surface of the ruled line diffraction grating film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above faced each other. Using DX-350, 120 ° C, 0.3MP
a, Heating and pressurization was performed under the condition of a roll contact time of 0.5 seconds. After cooling to room temperature, the ruled line diffraction grating film was removed.

When the cholesteric alignment film surface on which the diffraction grating film was superimposed was observed, it was clearly observed that the iridescent color caused by the diffraction pattern and the selective reflection peculiar to the cholesteric liquid crystal were observed. Also, when the orientation state of the cholesteric alignment film surface from which the diffraction grating film was removed was observed by a polarizing microscope and a transmission electron microscope of the liquid crystal layer cross section, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction. It was also confirmed that cholesteric alignment in which the helical pitch was not uniformly spaced in the film thickness direction was formed in the surface region of the liquid crystal layer. In other regions, it was confirmed that a cholesteric orientation in which the helical axis orientation was uniformly parallel to the film thickness direction and the helical pitch was uniformly uniform in the film thickness direction was formed.
In addition, He-N
When an e-laser (wavelength 632.8 nm) is incident,
Laser light was observed at emission angles of 0 ° and about ± 35 °. In order to further confirm the polarization characteristics, the obtained laminate was placed under normal room illumination and observed through a right circularly polarizing plate (transmitting only right circularly polarized light). And the brightness when observed without a polarizing plate was almost the same. On the other hand, a left circularly polarizing plate (only left circularly polarized light is transmitted)
Observed through the above, a dark field was obtained, and no iridescent reflected and diffracted light was observed.

From these results, it was confirmed that in the cholesteric alignment film, a region exhibiting diffractive ability was formed in the film surface region, and that the diffracted light was right-handed circularly polarized light. From this, it was found that the cholesteric liquid crystal film of the present invention was obtained by transferring the diffraction pattern of the diffraction grating film to the cholesteric alignment film.

(Example 3) Mw is 7000, Mw / Mn
A film was formed by spin coating on polyphenylene sulfide rubbed with a liquid crystalline polyester (containing an R-form optically active compound) having a 2.0, logarithmic viscosity of 0.144, Tg of 85 ° C and Ti of 230 ° C. Then, when the film was heat-treated at 200 ° C. for 5 minutes, a film having a golden specular reflection was obtained.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that a film in which the cholesteric orientation shown was fixed was formed.

The laminator manufactured by Tokyo Laminex Co., Ltd. is overlapped so that the diffraction surface of the ruled line diffractive element film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above face each other. Using DX-350, 120 ° C, 0.3MP
a, Heating and pressurization was performed under the condition of a roll contact time of 0.5 seconds. After cooling to room temperature, the ruled line diffraction grating film was removed.

When the cholesteric alignment film surface on which the diffraction grating film was superimposed was observed, the rainbow color caused by the diffraction pattern and the selective reflection peculiar to the cholesteric liquid crystal were clearly recognized. Also, when the orientation state of the cholesteric alignment film surface from which the diffraction grating film was removed was observed by a polarizing microscope and a transmission electron microscope of the liquid crystal layer cross section, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction. It was also confirmed that cholesteric alignment in which the helical pitch was not uniformly spaced in the film thickness direction was formed in the surface region of the liquid crystal layer. In other regions, it was confirmed that a cholesteric orientation in which the helical axis orientation was uniformly parallel to the film thickness direction and the helical pitch was uniformly uniform in the film thickness direction was formed.
In addition, He-N
When an e-laser (wavelength 632.8 nm) is incident,
Laser light was observed at emission angles of 0 ° and about ± 35 °. In order to further confirm the polarization characteristics, the obtained laminate was placed under normal room illumination and observed through a right circularly polarizing plate (transmitting only right circularly polarized light). And the brightness when observed without a polarizing plate was almost the same. On the other hand, a left circularly polarizing plate (only left circularly polarized light is transmitted)
Observed through the above, a dark field was obtained, and no iridescent reflected and diffracted light was observed.

From these results, it was confirmed that in the cholesteric alignment film, a region exhibiting diffractive ability was formed in the film surface region, and that the diffracted light was right-handed circularly polarized light. From this, it was found that the cholesteric liquid crystal film of the present invention was obtained by transferring the diffraction pattern of the diffraction grating film to the cholesteric alignment film.

An adhesive made of a commercially available photocurable acrylic oligomer was applied to the cholesteric liquid crystal surface of the obtained cholesteric liquid crystal film using a bar coater so as to have a thickness of 5 μm. Next, a triacetylcellulose film (support substrate) was bonded to the application surface using a desktop laminator, and irradiated with ultraviolet light to cure the adhesive. After curing the adhesive, hold the end of the polyphenylene sulfide film used as the alignment substrate by hand.
The polyphenylene sulfide film was peeled off in the direction of 80 ° at the interface between the polyphenylene sulfide film and the cholesteric liquid crystal layer.

Through the above steps, triacetylcellulose (supporting substrate) is laminated so that the surface on which the diffraction pattern has been transferred to the cholesteric liquid crystal film faces the triacetylcellulose side as the supporting substrate via the adhesive layer. A laminate of / adhesive layer / cholesteric liquid crystalline film was obtained.

(Example 4) Mw is 20000, Mw / M
n2.2, logarithmic viscosity 0.344, Tg 102 ° C, T
A film was formed by spin coating on polyphenylene sulfide which had been rubbed with a liquid crystalline polyester (containing an R-form optically active compound) having an i of 250 ° C. Subsequently, when heat-treated at 220 ° C. for 5 minutes, a film exhibiting a golden specular reflection was obtained.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that a film in which the cholesteric orientation shown was fixed was formed.

A laminator manufactured by Tokyo Laminex Co., Ltd. was overlapped so that the diffraction surface of a ruled-type diffraction grating film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above faced each other. Using DX-350, 150 ° C, 3MPa,
The heating and pressurization were performed under the condition of a roll contact time of 0.5 seconds. After cooling to room temperature, the ruled line diffraction grating film was removed.

When the surface of the cholesteric alignment film on which the diffraction grating film was superimposed was observed, the rainbow color caused by the diffraction pattern and the selective reflection characteristic of the cholesteric liquid crystal were clearly recognized. Also, when the orientation state of the cholesteric alignment film surface from which the diffraction grating film was removed was observed by a polarizing microscope and a transmission electron microscope of the liquid crystal layer cross section, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction. It was also confirmed that cholesteric alignment in which the helical pitch was not uniformly spaced in the film thickness direction was formed in the surface region of the liquid crystal layer. In other regions, it was confirmed that a cholesteric orientation in which the helical axis orientation was uniformly parallel to the film thickness direction and the helical pitch was uniformly uniform in the film thickness direction was formed.
In addition, He-N
When an e-laser (wavelength 632.8 nm) is incident,
Laser light was observed at emission angles of 0 ° and about ± 35 °. In order to further confirm the polarization characteristics, the obtained laminate was placed under normal room illumination and observed through a right circularly polarizing plate (transmitting only right circularly polarized light). And the brightness when observed without a polarizing plate was almost the same. On the other hand, a left circularly polarizing plate (only left circularly polarized light is transmitted)
Observed through the above, a dark field was obtained, and no iridescent reflected and diffracted light was observed.

From these results, it was confirmed that in the cholesteric alignment film, a region exhibiting diffractive ability was formed on the film surface region, and that the diffracted light was right-handed circularly polarized light. From this, it was found that the cholesteric liquid crystal film of the present invention was obtained by transferring the diffraction pattern of the diffraction grating film to the cholesteric alignment film.

An adhesive made of a commercially available photo-curable acrylic oligomer in which an ultraviolet absorber and a hard coat agent were blended using a bar coater was applied to the cholesteric liquid crystal surface of the obtained cholesteric liquid crystal film with a thickness of 5 μm.
It applied so that it might become. Next, a polyethylene terephthalate film was adhered to the application surface using a desktop laminator, and irradiated with ultraviolet light to cure the adhesive. After the adhesive was cured, the end of the polyphenylene sulfide film used as the alignment substrate was held by hand, and the polyphenylene sulfide film was peeled in the 180 ° direction at the interface between the polyphenylene sulfide film and the cholesteric liquid crystal layer.

Next, a triacetylcellulose film is bonded to the cholesteric liquid crystal layer from which the polyphenylene sulfide film has been peeled off via an ultraviolet-curable adhesive by using a table-top laminator, and is irradiated with ultraviolet light to cure the adhesive. The terephthalate film is peeled off at the interface with the adhesive layer containing an ultraviolet absorber and a hard coat agent, and a protective layer (adhesive layer (containing an ultraviolet absorber and a hard coat agent)) / cholesteric liquid crystal film / adhesive layer / A laminate comprising a triacetyl cellulose film was obtained.

(Comparative Example 1) Mw is 950, Mw / Mn
2, logarithmic viscosity 0.06, Tg 60 ° C, Ti 220
° C liquid crystalline polyester (contains R-form optically active compound)
Was formed on a rubbed polyphenylene sulfide by spin coating. Subsequently, when heat-treated at 180 ° C. for 5 minutes, a film exhibiting a golden specular reflection was obtained.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that a film in which the cholesteric orientation shown was fixed was formed.

A laminator manufactured by Tokyo Laminex Co., Ltd. is overlapped so that the diffraction surface of the ruled line diffraction grating film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above face each other. Using DX-350, 120 ° C, 0.3MP
a, Heating and pressurization was performed under the condition of a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled line diffraction grating film was removed. In the obtained film, cracks occurred in a part of the film, and the cholesteric orientation was disturbed and uneven alignment occurred. Neither did iridescence caused by the diffraction pattern.

Comparative Example 2 Mw (weight average molecular weight) was about 120,000, Mw / Mn was 4.0, logarithmic viscosity was 2.0, Tg
Is 150 ° C and Ti is 240 ° C.
(Containing an optically active compound) on a rubbed polyphenylene sulfide by spin coating.
After heat treatment at 20 ° C. for 20 minutes, a light yellowish film exhibiting weak selective reflection was obtained.

When the transmission spectrum of this film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the center wavelength was not clearly specified at about 550 to 600 nm. Showed a broad weak selective reflection. When observed with a microscope BX50 manufactured by Olympus Corporation, a number of alignment defects were observed in the liquid crystal layer.

Next, a ruled diffraction grating film (900 / m) manufactured by Edmund Scientific Japan
m) and the liquid crystal surface of the film obtained above are overlapped with each other, and a laminator D manufactured by Tokyo Laminex Co., Ltd.
Using X-350, heating and pressing were performed under the conditions of 120 ° C., 3 MPa, and a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled line diffraction grating film was removed. On the liquid crystal surface from which the diffraction grating film was removed, more alignment defects occurred, and no iridescent color due to the diffraction pattern was exhibited.

(Comparative Example 3) Mw is 95,000, Mw / M
n = 6.0, logarithmic viscosity = 1.5, Tg = 145 ° C., Ti
Is formed on a polyphenylene sulfide rubbed with a liquid crystalline polyester (containing an R-form optically active compound) at 240 ° C. by spin coating and then heat-treated at 220 ° C. for 20 minutes. was gotten.

When the transmission spectrum of this film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the center wavelength was about 550 to 600 nm, and the film could not be clearly identified. Showed a broad weak selective reflection. When observed with a microscope BX50 manufactured by Olympus Corporation, a number of alignment defects were observed in the liquid crystal layer.

Next, a ruled line diffraction grating film (900 / m) manufactured by Edmund Scientific Japan
m) and the liquid crystal surface of the film obtained above are overlapped with each other, and a laminator D manufactured by Tokyo Laminex Co., Ltd.
Using X-350, heating and pressing were performed under the conditions of 120 ° C., 3 MPa, and a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled line diffraction grating film was removed. On the liquid crystal surface from which the diffraction grating film was removed, more alignment defects occurred, and no iridescent color due to the diffraction pattern was exhibited.

(Comparative Example 4) Mw is 98,000, Mw / M
n is 3.0, logarithmic viscosity is 1.8, Tg is 205 ° C, Ti
Is formed on a rubbed polyphenylene sulfide by rubbing a liquid crystalline polyester (containing an R-form optically active compound) at 250 ° C. by a spin coating method and then heat-treated at 230 ° C. for 20 minutes to give a pale yellow weak selective reflection film was gotten.

When the transmission spectrum of this film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the center wavelength was not clearly specified at about 550 to 600 nm. Showed a broad weak selective reflection. When observed with a microscope BX50 manufactured by Olympus Corporation, a number of alignment defects were observed in the liquid crystal layer.

Then, a ruled diffraction grating film (900 / m) manufactured by Edmund Scientific Japan
m) and the liquid crystal surface of the film obtained above are overlapped with each other, and a laminator D manufactured by Tokyo Laminex Co., Ltd.
Using X-350, heating and pressing were performed under the conditions of 120 ° C., 3 MPa, and a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled line diffraction grating film was removed. On the liquid crystal surface from which the diffraction grating film was removed, more alignment defects occurred, and no iridescent color due to the diffraction pattern was exhibited.

Comparative Example 5 Mw (weight average molecular weight) was 1
040, Mw / Mn 2.1, logarithmic viscosity 0.06, T
A film was formed by spin coating on polyphenylene sulfide rubbed with a liquid crystalline polyester (containing an R-form optically active compound) having a g of 15 ° C and a Ti of 36 ° C.
After heat treatment for 5 minutes, a film exhibiting a golden specular reflection was obtained.

When the transmission spectrum of the film was measured by an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that the cholesteric liquid crystal layer shown was formed.

A laminator manufactured by Tokyo Laminex Co., Ltd. is overlapped so that the diffraction surface of the ruled line diffractive element film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above face each other. 40 ° C, 0.3MP using DX-350
a, Heating and pressurization was performed under the condition of a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled-type diffraction element film was removed.

In the obtained film, a part of the cholesteric liquid crystal phase was transferred to the isotropic phase, the cholesteric alignment was disturbed, and the alignment was uneven. Neither did iridescence caused by the diffraction pattern.

(Comparative Example 6) Mw (weight average molecular weight) of 1
030, Mw / Mn of 2.2, logarithmic viscosity of 0.046,
A film was formed by spin coating on polyphenylene sulfide rubbed with a liquid crystalline polyester (containing an R-form optically active compound) having a Tg of 20 ° C. and a Ti of 115 ° C.
After heat treatment at 00 ° C. for 5 minutes, a film having a golden specular reflection was obtained.

When the transmission spectrum of the film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the selective reflection having a center wavelength of about 600 nm and a selective reflection wavelength bandwidth of about 100 nm was observed. It was confirmed that a film in which the cholesteric orientation shown was fixed was formed.

A laminator manufactured by Tokyo Laminex Co., Ltd. was overlapped so that the diffraction surface of the ruled line diffractive element film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the cholesteric alignment film obtained above faced each other. Using DX-350, 50 ° C, 0.3MP
a, Heating and pressurization was performed under the condition of a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled-type diffraction element film was removed.

In the obtained film, a part of the film was cracked, and the cholesteric alignment was disturbed, and the alignment was uneven. Neither did iridescence caused by the diffraction pattern.

(Comparative Example 7) Mw is 98900, Mw / M
n = 4.0, logarithmic viscosity = 2.5, Tg = 148 ° C., Ti
Is formed on a rubbed polyphenylene sulfide by rubbing a liquid crystalline polyester (containing an R-form optically active compound) at 250 ° C. by spin coating, and then heat-treated at 220 ° C. for 20 minutes to give a pale yellow weak selective reflection film was gotten. When the transmission spectrum of this film was measured with an ultraviolet-visible-near-infrared spectrophotometer V-570 manufactured by JASCO Corporation, the center wavelength was not clearly specified at about 550 to 600 nm, and the selective reflection wavelength band was broad. It showed weak selective reflection. When observed with a microscope BX50 manufactured by Olympus Corporation, a number of alignment defects were observed in the liquid crystal layer, and uniform cholesteric alignment was not obtained. Next, a laminator DX-350 manufactured by Tokyo Laminex Co., Ltd. was overlapped so that the diffraction surface of the scored type diffraction grating film (900 lines / mm) manufactured by Edmund Scientific Japan and the liquid crystal surface of the film obtained above faced each other. Used, 12
The heating and pressurization were performed under the conditions of 0 ° C., 3 MPa, and a roll contact time of 0.5 seconds. Next, after cooling to room temperature, the ruled line diffraction grating film was removed.

The liquid crystal surface from which the diffraction grating film has been removed is:
Further, many alignment defects were generated, and no iridescent color due to the diffraction pattern was exhibited.

[0096]

The cholesteric liquid crystalline film of the present invention has unique optical characteristics such as diffracted light having a circular polarization property, which are not present in conventional optical elements, and its application range is extremely wide as a diffraction function element. For example, it can be suitably used as an optical member such as an optical element, an optoelectronic element, a decoration material, and a forgery prevention element.

Claims (1)

[Claims] 1. A weight average molecular weight Mw measured by GPC (in terms of polystyrene) of 1,000 to 100,000, a molecular weight distribution (Mw / Mn; Mn is a number average molecular weight) of 5 or less, and a logarithmic viscosity of 0.05 to 2.0. (Phenol / tetrachloroethane (60/40 weight ratio) mixed solvent 0.5g concentration)
/ Dl (temperature 30 ° C)) and a glass transition temperature (Tg) of 2
100 ° C. or less, and the transition temperature from the liquid crystal phase to the isotropic phase (T
A cholesteric liquid crystal film, wherein i) is a film formed from a film material containing a polymer liquid crystal as an essential component and having a temperature of 40 ° C. or higher, wherein a region having diffractive ability is formed in a part of the film.