JP2001066431A - Method for production of polarization diffraction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polarization diffraction device having all of selective reflection characteristics, characteristics of circularly polarized light, and diffraction ability. SOLUTION: A film is formed from a liquid crystal material containing a compound expressed by general formula (1), a compound expressed by general formula (2) and a low mol.wt. compound having an optically active part. The liquid crystal material in a cholesteric alignment state is crosslinked to prepare a cholesteric liquid crystal film. Then a region having diffraction ability is added to the film. In general formulae (1) and (2), each of R1, R2, R3 is independently hydrogen or a methyl group, X is one kind selected from hydrogen, chlorine, bromine, iodine, 1-4C alkyl groups, methoxy groups, cyano groups and nitro groups, and each of a, b, c is an integer of 2 to 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a polarization diffraction element capable of generating a 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.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide two kinds of non-optically active compounds which can be easily synthesized at low cost and an optically active low molecular weight compound for forming a cholesteric phase in a molecular arrangement. An object of the present invention is to provide a method for manufacturing a polarization diffraction element having a selective reflection characteristic and a circular polarization characteristic from a liquid crystal material to be contained and further having a diffraction ability.

[0004]

That is, a method for producing a polarization diffraction element according to the present invention comprises a compound (I) represented by the following general formula (1) and a compound (I) represented by the following general formula (2). A cholesteric liquid crystal film was prepared by forming a film from the compound (II) and a liquid crystal material containing a low-molecular compound having an optically active site, and crosslinking the liquid crystal material in a state where the liquid crystal material was cholesterically aligned. Thereafter, the cholesteric liquid crystal film is provided with a region exhibiting a diffractive ability.

Embedded image (In the general formulas (1) and (2), R ¹ , R ² and R ³
Each independently represents hydrogen or a methyl group, X represents hydrogen,
It represents one selected from the group consisting of chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group and a nitro group, and a, b and c each represent an integer of 2 to 12. The liquid crystal material used in the present invention has a compound (I): compound (II) weight ratio of 99: 1 to 50:50 contained therein.
And the content of the low molecular weight compound having an optically active site (hereinafter referred to as an optically active low molecular weight compound) is 100 parts by weight based on 100 parts by weight of the total amount of the compound (I) and the compound (II).
It is preferably in the range of 0.01 to 60 parts by weight. In the liquid crystal material used in the present invention, the optically active low molecular compound contained therein is preferably a compound (III) represented by the following general formula (3) or (4).

Embedded image (In the general formulas (3) and (4), R ⁴ represents hydrogen or a methyl group, d and e each represent an integer of 2 to 12, and Y is selected from the following (i) to (xxiv). One of the divalent groups shown below.)

Embedded image Here, Z in the above (i) and (ii) represents one selected from the group consisting of hydrogen, chlorine, bromine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group and a nitro group.

Embedded image

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The polarization diffraction element of the present invention is manufactured by first preparing a cholesteric liquid crystal film, and then giving a region exhibiting diffractive power to the liquid crystal film. The cholesteric liquid crystal film comprises a liquid crystal compound (I) represented by the general formula (1), a non-liquid crystal compound (II) represented by the general formula (2), and an optically active low molecular compound. The liquid crystal material is formed by forming a liquid crystal material including the liquid crystal material and crosslinking the liquid crystal molecules in a state where the liquid crystal molecules in the film are cholesterically aligned. In the general formula (1) representing the compound (I), R
¹ and R ² each independently represent hydrogen or a methyl group,
It is preferable that both R ¹ and R ² be hydrogen in view of the wide temperature range showing the liquid crystal phase. X may be any of hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, and a nitro group, but is preferably a chlorine or methyl group. A (meth) acryloyloxy group at both molecular chains of the compound (I);
A and b indicating the chain length of the alkylene group which is a spacer with the aromatic ring can each independently take an arbitrary integer in the range of 2 to 12, but is preferably in the range of 4 to 10,
More preferably, it is in the range of 6 to 9. a = b = 0
Is poor in stability, easily susceptible to hydrolysis, and has high crystallinity of the compound itself. Further, the compound of the general formula (1) in which a and b are each 13 or more has a low isotropic transition temperature (TI).
For this reason, these compounds are not preferable because the temperature range in which they exhibit liquid crystallinity is narrow. Compound (I) can be synthesized by any method. For example, the compound (I) in which X is a methyl group can be obtained by an esterification reaction between 1 equivalent of methylhydroquinone and 2 equivalents of 4-((meth) acryloyloxyalkoxy) benzoic acid. In the esterification reaction, the above-mentioned benzoic acid is generally activated with an acid chloride, sulfonic anhydride or the like, and the benzoic acid is reacted with methylhydroquinone. Further, a carboxylic acid unit can be directly reacted with methylhydroquinone by using a condensing agent such as DCC (dicyclohexylcarbodiimide). Alternatively, one equivalent of methylhydroquinone and two equivalents of 4- (benzyloxyalkoxy)
The compound (I) can also be synthesized by a method of first performing an esterification reaction with benzoic acid, then debenzylating the obtained ester by a hydrogenation reaction or the like, and then acryloylating the molecular terminal. In carrying out the esterification reaction between methylhydroquinone and 4- (benzyloxyalkoxy) benzoic acid, methylhydroquinone is introduced into diacetate and then reacted with the above benzoic acid in a molten state to obtain an ester directly. It is possible.
Also in the case of the compound (I) in which X in the general formula (1) is not a methyl group, a hydroquinone having a corresponding substituent can be obtained by the same synthetic method as described above, instead of methylhydroquinone.

In the general formula (2) representing the compound (II), R ³ represents hydrogen or a methyl group. In order to obtain a liquid crystal material forming a liquid crystal layer in a wide temperature range, R ³ must be hydrogen. Is preferred. Although the compound (II) does not show liquid crystallinity, considering the compatibility with the liquid crystalline compound (I),
C representing the chain length of the alkylene group in the general formula (2) is 4 to 1
It is preferably in the range of 0, and more preferably in the range of 6 to 9. Compound (II) can also be synthesized by any method. For example, the compound (I) is obtained by an esterification reaction between one equivalent of 4-cyanophenol and one equivalent of 4-((meth) acryloyloxyalkoxy) benzoic acid.
I) can be synthesized. This esterification reaction activates the above-mentioned benzoic acid with an acid chloride, sulfonic anhydride or the like, as in the case of synthesizing the compound (I).
It is common to react with cyanophenol.
The above-mentioned benzoic acid and 4-cyanophenol may be reacted with a condensing agent such as DCC (dicyclohexylcarbodiimide).

Another component of the liquid crystal material used in the present invention is an optically active low molecular compound that induces a twist in the positive uniaxial nematic liquid crystal expressed by the compounds (I) and (II). Here, the optically active low molecular weight compound means a compound having an optically active site and having a molecular weight of 1500 or less. The optically active low molecular weight compound of the present invention is compatible with either or both of the compound (I) and the compound (II) in a solution state or a molten state, and the compound (I) and the compound (II) are expressed. There is no limitation on the type of the positive uniaxial nematic liquid crystal as long as it can induce a desired twist. A low-molecular compound used to induce twist in a liquid crystal generally has an optically active site somewhere in the molecule. In other words, they possess chirality. Therefore, for example, a compound having one or more asymmetric carbon atoms, a compound having an asymmetric point on a hetero atom such as a chiral amine or a chiral sulfoxide, or an axial asymmetry such as cumulene or binaphthol. Are all optically active low molecular compounds that can be used in the present invention. Commercially available chiral nematic liquid crystals, for example, S-811 manufactured by Merck are also optically active low molecular compounds that can be used in the present invention. When preparing a liquid crystal film from the liquid crystal material of the present invention, in order to express a cholesteric liquid crystal of a short pitch such that the selective reflection band is near the visible light wavelength in the film, it is necessary to induce a strong twist in the liquid crystal, The amount of the optically active low molecular compound to be contained in the liquid crystal material must be increased as compared with a case where a strong twist is not required. But,
Depending on the type of the selected optically active low-molecular compound, an increase in the amount may cause destruction of the nematic liquid crystal formed by the compound (I) and the compound (II) and a decrease in the alignment property. When such a low molecular weight compound is non-polymerizable, the increase in the amount thereof impairs the cross-linking property of the liquid crystal molecules, which may lower the reliability of the liquid crystal film. Therefore, when producing a cholesteric liquid crystal film of a short pitch, it is preferable to select a compound having a large torsion force as the low-molecular compound having an optically active site to be contained in the liquid crystal material. It is preferable to use a low molecular compound (III) having axial asymmetry in the molecule as represented by (3) or (4).

In the general formula (3) or (4) representing the low molecular compound (III), R ⁴ represents hydrogen or a methyl group. Y is any one of the expressions (i) to (xxiv) shown above, and among them, the expressions (i), (ii), and (ii)
Preferably, it is one of i), (v) and (vii). Further, d and e indicating the chain length of the alkylene group are
Each of them may independently take an arbitrary integer in the range of 2 to 12, but is preferably in the range of 4 to 10, and more preferably in the range of 6 to 9. The compound of the general formula (3) or (4) in which the value of d or e is 0 or 1 lacks stability, is susceptible to hydrolysis, and has high crystallinity. On the other hand, d
Alternatively, a compound having a value of e of 13 or more has a low melting point (Tm). These compounds are compound (I) and compound (II)
When it is used darely, the liquid crystal material may cause phase separation depending on the concentration. The low molecular compound (III) can be synthesized by any method.
For example, one equivalent of (R)-(+)-or (S)-(-)-1,1′-bi-2-naphthol and two equivalents of a carboxylic acid having a (meth) acryloyloxyalkoxy group or The low molecular compound (III) can be synthesized by an esterification reaction with a carboxylic acid having an alkoxy group. Incidentally, in the general formula (3) or (4), Y is the above-mentioned formula (i) or (i).
i) wherein the low molecular compound (III) in which Z is hydrogen, in other words, the low molecular compound (III) in which Y in the general formula (3) or (4) is a phenylene group
Is one equivalent of (R)-(+)-or (S)-(-)-1,1′-bi-2-naphthol and two equivalents of 4-((meth) acryloyloxyalkoxy) benzoic acid Alternatively, it can be produced by an esterification reaction with 4-alkoxybenzoic acid. In this esterification, as in the case of synthesizing the compound (I) or the compound (II), the carboxylic acid as a raw material is activated by introducing it into an acid chloride or a sulfonic anhydride, and this is reacted with 4-cyanophenol. Can be employed, but DCC is preferred for the purpose of preventing racemization of the low molecular weight compound (III).
It is particularly preferable to employ a method of directly reacting the starting carboxylic acid with 4-cyanophenol using a condensing agent such as (dicyclohexylcarbodiimide).

In the liquid crystal material used in the present invention, the relative amounts of the compound (I) and the compound (II) are determined in consideration of the molecular length of each compound used and the characteristics of the polarization diffraction element to be finally manufactured. In general, the weight ratio of the compound (I) to the compound (II) is from 99: 1 to 5
0:50, preferably 95: 5 to 60:40, more preferably 90:10 to 65:35, most preferably 8
It is selected in the range of 5:15 to 70:30. When the amount of the compound (I) contained in the liquid crystal material exceeds 99% by weight of the total amount of the compound (I) and the compound (II), the crystallinity of the compound (I) is relatively high. Thus, satisfactory liquid crystallinity cannot be imparted to a film obtained from a liquid crystal material. On the other hand, if the above amount is less than 50% by weight, the isotropic transition temperature (TI) of the liquid crystal material is lowered, so that the liquid crystal phase temperature range becomes extremely narrow, which is not preferable. The amount of the optically active low molecular weight compound (including the case where the low molecular weight compound (III) is used) to be blended in the liquid crystal material of the present invention, the twist inducing ability inherent to the compound, and the finally obtained polarization diffraction element The optimum value is determined in consideration of the performance required for the liquid crystal material. In general, 0.01 to 60 parts by weight per 100 parts by weight of the total amount of the compound (I) and the compound (II) constituting the liquid crystal material Parts, preferably 0.1 to 40
Parts by weight, more preferably 0.5 to 30 parts by weight, most preferably 1 to 20 parts by weight. If the amount is less than 0.01 part by weight, sufficient cholesteric properties may not be imparted to the liquid crystal material. If the amount is more than 60 parts by weight, the orientation of the molecules may be impaired and adversely affect crosslinking. There is. In preparing the liquid crystal material of the present invention, two or more compounds (I), compounds (II) and optically active low molecular compounds can be used as necessary. Compounds other than those described above can be appropriately added to the liquid crystal material used in the present invention as long as the object of the present invention is not impaired. Examples of the compound that can be added include, for example, a polyester prepolymer obtained by condensing a polyhydric alcohol and a monobasic acid or a polybasic acid,
Polyester (meth) acrylate obtained by reacting (meth) acrylic acid; a compound having a polyol group and two isocyanate groups reacted with each other, and then the reaction product is reacted with (meth) acrylic acid. Polyurethane (meth) acrylate; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, polycarboxylic acid polyglycidyl ester, polyol polyglycidyl ether, aliphatic or alicyclic epoxy resin, amine epoxy resin, Photopolymerizable compound such as epoxy (meth) acrylate obtained by reacting epoxy resin such as phenol methane type epoxy resin and dihydroxybenzene type epoxy resin with (meth) acrylic acid; photopolymerizable having acrylic group or methacryl group Liquid crystal Compounds, and the like. The addition amount of these compounds is selected within a range that does not impair the object of the present invention, and is generally 40% by weight or less, preferably 20% by weight or less of the liquid crystal material. By adding these compounds, the crosslinkability of the liquid crystal material can be improved, the mechanical strength of the crosslinked film can be increased, and the stability of the liquid crystal phase can be improved.
The liquid crystal material of the present invention can be cross-linked by irradiation with an electron beam even in the absence of a photoreaction initiator. If necessary, one or more photoreaction initiators may be used in an amount of 0.01 to
20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight can be added to the liquid crystal material used in the present invention. Illustrative photoinitiators that can be used include benzyl, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate,
4-benzoyl-4'-methyldiphenyl sulfide, benzylmethyl ketal, dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3'-dimethyl-4- Methoxybenzophenone, methylobenzoyl formate, 2-methyl-1-
(4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecyl) Phenyl) -2-hydroxy-
2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane Examples thereof include -1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and 1-chloro-4-propoxythioxanthone. In addition to the photoreaction initiator, various additives such as a sensitizer, a dichroic dye, a dye, a pigment, an ultraviolet absorber, a hard coat agent, and an antioxidant may be appropriately used as long as the object of the present invention is not impaired. It is also possible to add.

When forming the liquid crystal material of the present invention, a method of casting a liquid crystal material in a molten state or a solution state on a support film can be adopted. Above all, a liquid crystal material is dissolved in a solvent, and this solution is applied on a support film or a substrate to form a coating layer. Then, the coating layer is dried to evaporate the solvent, and then a dried film is required. This is a method of performing a heat treatment in accordance with this. Hereinafter, a method for producing this film will be described in detail. Solvent for solution preparation Solvent used for dissolution or dispersion of liquid crystal material, for example,
Benzene, toluene, xylene, n-butylbenzene,
Hydrocarbons such as diethylbenzene and tetralin, methoxybenzene, 1,2-dimethoxybenzene, ethers such as diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ketones such as 2,4-pentanedione, ethyl acetate, Esters such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, γ-butyrolactone, 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide,
Amide solvents such as dimethylacetamide, halogen solvents such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, tert-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene Alcohols such as glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, butyl cellosolve,
One or more phenols such as phenol and parachlorophenol can be used. Even if only a single type of solvent is used, the solubility of the liquid crystal material is insufficient, or even if the support film described below may be eroded, by mixing and using two or more types of solvents, Inconvenience can be avoided. Among the above solvents, preferred as a single solvent are a hydrocarbon-based solvent and a glycol monoether acetate-based solvent, and preferred as a mixed solvent medium is a mixture of an ether or a ketone and a glycol. System. The concentration of the solution cannot be specified unconditionally because it depends on the solubility of the liquid crystal material, the thickness of the film to be produced, and the like.
It is adjusted in the range of 0% by weight, preferably in the range of 3 to 40% by weight. A surfactant or the like can be added to the solution of the liquid crystal material to facilitate application. Illustrative surfactants that can be added are imidazoline, quaternary ammonium salts,
Alkylamine oxides, cationic surfactants such as polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, primary or secondary alcohol ethoxylates, alkylphenol ethoxylates, polyethylene glycol and its esters, sodium lauryl sulfate, Anionic surfactants such as ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, lauryl amide propyl betaine, lauryl amino acetate betaine, etc. Amphoteric surfactants, polyethylene glycol fatty acid esters,
Nonionic surfactants such as polyoxyethylene alkylamine, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group / hydrophilic group Oligomers, perfluoroalkyl / lipophilic group-containing oligomers, perfluoroalkyl group-containing urethanes, and other fluorinated surfactants. The amount of surfactant added depends on the type of surfactant, type of liquid crystal material, type of solvent,
Further, although it depends on the type of the support film to which the solution is applied, usually, 10 ppm by weight or less of the liquid crystal material contained in the solution is used.
10% by weight, preferably 100% by weight to 5% by weight,
More preferably, it is in the range of 0.1 to 1% by weight.

[0011] Support film, support substrate and arrangement thereon
The solution of the liquid crystal material for imparting function is applied on a support film or a substrate. As the support film, for example, polyimide, polyamide imide, polyamide, polyether imide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, Plastic films such as polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose, triacetyl cellulose and partially saponified products thereof, epoxy resin and phenol resin can be used. These plastic films may be laminated films obtained by laminating two or more kinds of films, or may be uniaxially stretched or biaxially stretched films. Further, the support film can be subjected to a surface treatment such as a hydrophilic treatment or a hydrophobic treatment in advance. Depending on the composition of the liquid crystal material contained in the solution, it is not necessary to separately impart alignment ability to the support film, but in the present invention, it is desirable to impart alignment ability to the support film prior to application of the solution. The orientation ability can be imparted by laminating an orientation film on the support film or by rubbing the support film or the orientation film laminated thereon. Alternatively, silicon oxide may be obliquely vapor-deposited on the support film to impart orientation ability. As the alignment film, a film formed of polyimide, polyamide, polyvinyl alcohol, or the like is usually used, and the rubbing treatment is performed by winding a rubbing cloth selected from materials such as rayon, cotton, and polyamide on a metal roll, and applying this to a film. A method in which the film surface or the alignment film surface is rubbed with a rubbing cloth is usually adopted by rotating the film in a contact state or by transporting the film while fixing the roll. Instead of the above-described support film, a metal substrate such as aluminum, iron, or copper having a slit-shaped groove on the surface, or a glass substrate such as an alkali glass, a borosilicate glass, or a flint glass, whose surface is etched into a slit shape. It can also be used. If necessary, a diffraction element substrate described later can be used as a support film or a support substrate.

The application of the solution and the application of the solution to the dried support film or the support substrate can be arbitrarily adopted by a spin coating method, a roll coating method, a printing method, an immersion pulling method, a curtain coating method (die coating method), or the like. is there. The coating layer is then dried to evaporate the solvent in the coating layer. To dry the coating layer, air drying at room temperature, drying on a hot plate, drying in a drying oven, blowing of hot air or hot air, etc. are used, and the degree of drying is such that the coating layer flows, It does not need to run off. Depending on the composition of the liquid crystal material contained in the coating layer, the liquid crystal molecules in the coating layer complete the cholesteric alignment in the course of drying in which the solvent is removed in a thermotropic or lyotropic manner. In some cases, no alignment treatment is required.
However, to make the orientation of the liquid crystal more perfect,
After the drying step, it is desirable to subject the dried coating layer to heat treatment. In the heat treatment method, the coating layer is heated above the liquid crystal transition point of the liquid crystal material to a liquid crystal state, and this state is maintained for a predetermined time. The liquid crystal molecules are isotropic by heating to a temperature higher than the liquid crystal transition point. After the liquid state, the temperature is lowered to the liquid crystal state,
A method of maintaining this state for a predetermined time can be employed. The heat treatment of the dried coating film layer is usually performed in a temperature range of 30 to 220 ° C, preferably in a range of 50 to 180 ° C, and more preferably in a range of 60 to 160 ° C. The treatment time depends on the composition of the liquid crystal material contained in the coating layer, but is usually in the range of 5 seconds to 2 hours, preferably 10 seconds to 40 minutes, particularly preferably 20 seconds to 20 minutes. Heat treatment time 5
If the time is less than 2 seconds, the molecules may not be sufficiently oriented, and 2
Heat treatment exceeding the time may cause a decrease in productivity, which is not desirable.

Crosslinking of the Coating Layer The liquid crystal molecules forming the coating layer are crosslinked in a state of cholesteric alignment. The crosslinking includes electron beam, ultraviolet ray, visible light ray, infrared ray (heat ray). And the like. Usually, ultraviolet light or visible light is used, and the wavelength is 150 to 700 nm, preferably 250 to 65 nm.
Irradiation light of 0 nm, more preferably 300 to 500 nm is used. Light sources for this irradiation light include low-pressure mercury lamps (germicidal lamps, fluorescent chemical lamps, black lights), high-pressure discharge lamps (high-pressure mercury lamps, metal halide lamps), and short arc discharge lamps (ultra-high-pressure mercury lamps, xenon lamps, mercury xenon lamps) Lamp). Of these, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended. At the time of light irradiation, a filter can be provided between the light source and the irradiation target, and the irradiation target can be exposed to light in a specific wavelength region. The irradiation light amount is adjusted depending on the composition of the liquid crystal material forming the coating layer and the presence or absence of the initiator,
Generally, it is ^{2 to} 5000 mJ / cm ² , more preferably 10 to 3000 mJ / cm ² , and still more preferably 10 to 3000 mJ / cm ² .
The range is from 0 to 2000 mJ / cm ² . The ambient temperature at the time of light irradiation is appropriately selected depending on the physical and chemical properties of the coating layer, but is usually 0 to 200 ° C, preferably 20 to 180 ° C, and more preferably 25 to 160 ° C. In the range. However, for example, a liquid crystal material having a higher-order phase such as a smectic phase or a crystal phase in a low-temperature region near room temperature, and having a chiral nematic phase in a higher temperature region,
In the case of immobilization by photocrosslinking in the state of a chiral nematic phase, light irradiation may need to be performed at a temperature equal to or higher than the phase transition point between the higher-order phase and the chiral nematic phase.
In the heat treatment process prior to photocrosslinking, if the nematic phase was already fixed by supercooling, the crosslinking rate of the liquid crystal layer was low, so the coating layer was reheated to have fluidity. Light irradiation is preferably performed later. Light irradiation may be repeated several times. For example, by performing light irradiation once under heating to crosslink the coating layer to some extent, and then performing light irradiation again after cooling, the reaction rate of the photoreaction can be further improved. Further, after light irradiation, heat treatment may be performed again, and so-called aging may be performed to further react unreacted sites. The atmosphere in which the light irradiation is performed is not particularly limited. However, if the coating layer is susceptible to reaction inhibition by oxygen or ozone in the atmosphere, or if the coating layer and / or its supporting film may be colored by the influence of oxygen or ozone in the atmosphere, the irradiation atmosphere Is preferably an inert gas atmosphere such as nitrogen gas. As long as the orientation of liquid crystal molecules in the coating layer is not hindered, instead of using an inert gas atmosphere, it is possible to cover the coating layer surface with a film having oxygen or ozone blocking ability and perform light irradiation. is there. In this case, as the blocking film, for example, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyphenylene sulfide film, a polyarylate film, a polycarbonate film, a polyvinyl alcohol film, a polyvinyl acetate film, a polyethylene film, a polypropylene film, a polyvinyl chloride film, Polyvinylidene chloride film, polyamide film, polyimide film, polyethylene-vinyl acetate co-extruded film and the like can be used. A cholesteric liquid crystal film can be obtained on a supporting film or a supporting substrate by completing the crosslinking of the coating film layer.

A cholesteric liquid crystal film on a supporting film or a supporting substrate has a projection axis (hereinafter referred to as an orientation axis) of a liquid crystal molecule director on the film surface at an interface with the supporting film or the supporting substrate. The direction basically coincides with the rubbing direction (hereinafter referred to as a rubbing axis) of the supporting substrate, and the director rotates as it advances in the film thickness direction, and the rotation angle takes a value specific to the cholesteric liquid crystal film. Various optical parameters such as the wavelength bandwidth, film thickness, and number of twist turns of the cholesteric liquid crystal film can be appropriately adjusted depending on the performance and application required for the ultimately desired polarization diffraction element. The bandwidth is usually in the range of 15 to 120 nm, and the actual thickness of the liquid crystal layer is usually preferably 0.6 μm or more. Here, the wavelength bandwidth of the selective reflection refers to a wavelength range in which the reflectance due to the selective reflection becomes 70% or more when circularly polarized light in the same direction as the twist direction of the liquid crystal molecules forming the cholesteric alignment enters the liquid crystal film. Means that. When the wavelength bandwidth deviates from the above range, the cholesteric liquid crystal film itself is bright but the reflected light is dark,
Alternatively, the opposite case may occur, and the visibility may be degraded depending on the application. When the actual thickness of the liquid crystal layer is less than 0.6 μm, the selective reflection effect by cholesteric alignment may be reduced. Further, the number of twisted turns in the cholesteric orientation is usually desirably 2 or more. If it is less than two turns, there is a possibility that the selective reflection effect by the cholesteric orientation cannot be sufficiently obtained.

Add diffraction ability to cholesteric liquid crystal film
Given polarization diffraction element of the present invention is produced by applying a region exhibiting diffraction capability to a cholesteric liquid crystal film prepared as described above. In order to provide a region exhibiting diffractive power, the diffraction pattern (diffraction grating) of a separately prepared diffraction element is used.
A method of transferring to a cholesteric liquid crystal film surface is employed. The diffraction element used here means a substrate or a film having a desired diffraction pattern on its surface, and its material may be any of metal and plastic. Generally speaking, a diffractive element includes all diffractive elements that generate diffracted light, such as an original flat hologram, and includes not only a thickness-modulated hologram type diffractive element but also a refractive index modulated hologram type diffractive element. . The diffraction element used in the present invention is preferably a type of a film thickness modulation hologram in that the diffraction pattern information of the diffraction element can be more easily applied to the liquid crystal film. However, any type of refractive index modulation can be used in the present invention as long as it has undulations that cause diffraction in the surface shape. Actually, the diffraction pattern transfer is performed by using an appropriate device such as a compression molding machine, a rolling mill, a calender roller, a heat roller, a laminator, a hot stamp, an electric heating plate, and a thermal head, and the surface of the cholesteric liquid crystal film on the supporting film or the supporting substrate. Then, the diffraction element can be pressed against the diffraction pattern surface of the diffraction element. After the transfer, the diffraction element is removed from the liquid crystal film surface. The pressure transfer condition of the diffraction pattern is
Since it depends on various physical properties of the cholesteric liquid crystal film, the material of the diffractive element, etc., it cannot be said unconditionally. Usually, the temperature range is 40 to 300 ° C., preferably 70 to 180 ° C., and the pressure condition is 0.05. The range is from 80 to 80 MPa, preferably from 0.1 to 20 MPa. Incidentally, when the diffraction pattern is transferred to a cholesteric liquid crystal film having a sufficiently stable alignment state at room temperature, the transfer temperature is set to 40.
If the temperature is lower than ℃, the transfer of the diffraction pattern may be insufficient. If the temperature is higher than 300 ° C, the cholesteric liquid crystal film may be decomposed or deteriorated. When the transfer pressure is lower than 0.05 MPa, the transfer of the diffraction pattern may be insufficient, and when the transfer pressure is higher than 80 MPa, the cholesteric liquid crystal film or the like may be broken. The time required for transferring the diffraction pattern is usually 0.01 seconds or more, preferably 0.05 seconds to 1 minute. When the processing time is shorter than 0.01 second, the transfer of the diffraction pattern may be insufficient, and the processing time exceeding 1 minute is not desirable from the viewpoint of productivity.

The transfer of the diffraction pattern is not limited to only one side of the cholesteric liquid crystal film, but it is also possible to transfer the diffraction pattern to both sides. Further, the transfer of the diffraction pattern may be performed only on a selected area on one side or both sides of the cholesteric liquid crystal film. In any case, the cholesteric liquid crystal film can be provided with a region exhibiting a diffractive ability by transferring the diffraction pattern.
Here, the region exhibiting diffractive power means a region in which light transmitted through the region or light reflected by the region is found to enter a geometrically shadowed portion. The presence or absence of a region exhibiting diffractive power is confirmed by, for example, the presence or absence of light (higher-order light) emitted at a certain angle other than the light (0th-order light) that is transmitted or reflected linearly when a laser beam or the like is incident on the test region. can do. Also, the presence or absence of a region exhibiting a diffractive ability can be confirmed by observing the surface shape or cross-sectional shape of the liquid crystal film with an atomic force microscope, a transmission electron microscope, or the like. In addition, the area showing the diffraction power is
Any pattern can be used to model desired figures, pictograms, numbers, and the like. When a plurality of regions exhibiting diffractive power are provided on the liquid crystal film, it is not necessary that all regions have the same diffractive power, and each region can have its own diffractive power. The thickness of the region showing the diffractive power imparted to the cholesteric liquid crystal film surface, that is, the thickness of the diffraction layer is usually 50% or less, preferably 30% or less, more preferably 10% or less of the film thickness of the liquid crystal film. It is desirable to do. When the thickness of the diffraction layer exceeds 50% of the film thickness,
This is because the selective reflection characteristics, circular polarization characteristics, and the like of the cholesteric liquid crystal phase are impaired. In a general cholesteric liquid crystal film, the helical axis direction is uniformly parallel to the film thickness direction, and the helical pitch forms a helical structure that is evenly spaced in the film thickness direction. The liquid crystal film in the region preferably has a cholesteric orientation in which the helical axis direction is not uniformly parallel to the film thickness direction. In addition to the fact that the helical axis orientation is not uniformly parallel to the film thickness direction, it is further preferable that the helical pitch is not uniformly spaced in the film thickness direction.

As described above, the present invention provides a cholesteric liquid crystal film surface formed on a support film or a support substrate (hereinafter, referred to as an alignment support substrate for convenience) by providing a region exhibiting a diffractive ability. Can be used as it is, that is, with the alignment support substrate. However, if the alignment support substrate impairs the function as a polarization diffraction element, for example, if it has absorption in the used wavelength region, a cholesteric liquid crystal film having diffractive ability may be separated from the support film or the support substrate by another substrate (hereinafter, referred to as a support substrate). ,
(Referred to as “second substrate”). Second
Actually, the transfer to the substrate was performed by applying an appropriate adhesive to the surface of the cholesteric liquid crystal film to which the diffractive ability was imparted and bonding it to the second substrate. After the adhesive was cured, it was used when preparing the liquid crystal film. This is performed by a method of peeling the alignment support substrate from the liquid crystal film. The second substrate used for transfer is
The material 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, polyetherketone, polyketonesulfide , Polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyvinyl chloride, polystyrene, polypropylene, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyvinyl alcohol, polyacetal, polyarylate, cellulose-based plastic Sheet, film or board of paper, epoxy resin, phenolic resin, etc., paper such as paper, synthetic paper, metal foil It can be suitably selected from a glass plate or the like. Further, the second substrate may have a surface having irregularities. As the adhesive used for the transfer, usually, a photo-curing or electron beam-curing reactive adhesive, a hot-melt adhesive, or the like can be appropriately used. Reactive adhesives include photopolymerizable or electron beam polymerizable prepolymers and / or monomers, as required, other monofunctional or polyfunctional monomers, various polymers, stabilizers, photopolymerization initiators, sensitizers And the like,
Examples of the prepolymer include polyester acrylate, polyester methacrylate, polyurethane acrylate, polyurethane methacrylate, epoxy acrylate, epoxy methacrylate, polyol acrylate, and polyol methacrylate. Examples of the photopolymerizable or electron beam polymerizable monomer include monofunctional acrylate, monofunctional methacrylate, difunctional acrylate, difunctional methacrylate, trifunctional or higher polyfunctional acrylate, and polyfunctional methacrylate. Commercially available reactive adhesives include Aronix (acrylic special monomers and oligomers; manufactured by Toagosei Co., Ltd.),
Light ester (manufactured by Kyoeisha Chemical Co., Ltd.) and viscoat (manufactured by Osaka Organic Chemical Industry Co., Ltd.) can be exemplified. The photocurable adhesive can include a photopolymerization initiator such as a benzophenone derivative, an acetophenone derivative, a benzoin derivative, a thioxanthone, a Michler's ketone, a benzyl derivative, a triazine derivative, an acylphosphine oxide, or an azo compound. . The viscosity of the reactive adhesive can not be specified unconditionally because it is appropriately selected depending on the use temperature and the like, but is usually 10 to 2000 mPa · s at 25 ° C., preferably 50
１０００1000 mPa · s, more preferably 100 to 50
It is in the range of 0 mPa · s. When the viscosity is lower than 10 mPa · s, it is difficult to form an adhesive layer having a desired thickness, and when the viscosity is higher than 2000 mPa · s, workability may be reduced. The viscosity of the adhesive can be appropriately adjusted by adding a solvent thereto. In the adhesive,
Working temperature is 80-200 ° C, preferably 100-160
A hot-melt adhesive at about ℃ can be used in place of reactive adhesive, and similarly, rubber-based, acrylic-based,
A silicone-based or polyvinyl ether-based adhesive can also be used. Examples of hot melt adhesives include polyvinyl acetal such as ethylene-vinyl acetate copolymer-based resin, polyester-based resin, polyurethane-based resin, polyamide-based resin, thermoplastic rubber-based, polyacryl-based resin, polyvinyl alcohol-based resin, and polyvinyl butyral. Examples thereof include those manufactured using a base resin, a petroleum resin, a terpene resin, a rosin resin, or the like as a base resin. When applying an adhesive to the surface of the cholesteric liquid crystal film to which diffractive ability has been imparted and / or the surface of the second substrate, a roll coating method, a die coating method, a bar coating method,
Curtain coating, extrusion coating, gravure roll coating, spray coating, spin coating, and the like can be employed. The thickness of the adhesive is generally selected in the range of 0.5 to 50 μm, preferably 1 to 10 μm. For curing the photocurable adhesive layer, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like is used.
mJ / cm ² , preferably 100 to 1000 mJ / cm ²
It is. When the electron beam-curable adhesive layer is cured, it is general to irradiate an electron beam having an acceleration voltage of 50 to 1000 kV, preferably 100 to 500 kV. In any case, by curing the adhesive,
A laminate comprising an alignment support substrate / a cholesteric liquid crystal film provided with diffractive ability / adhesive layer / second substrate can be obtained.

In peeling the alignment supporting substrate from the above-mentioned laminate, any method can be adopted. For example, a method of applying an adhesive tape to a corner end of an alignment support substrate and mechanically peeling it off, a method of mechanically peeling after immersion in a poor solvent for all the structural materials constituting the laminate, Method of peeling by applying ultrasonic waves in, method of peeling by giving temperature change using difference in thermal expansion coefficient between alignment support substrate and cholesteric liquid crystal film, alignment support substrate itself, or alignment film on alignment support substrate Any of the methods for dissolving and removing the compound can be adopted. The polarization diffraction element obtained by removing the alignment support substrate can be provided with a protective layer on the surface for the purpose of protecting the surface, increasing the strength, and improving environmental reliability. The protective layer is usually an ultraviolet absorbing layer and / or a hard coat layer. The ultraviolet absorbing layer and the hard coat layer may each be two or more layers. Commercially available UV cut films and hard coat films can also be used for the protective layer. 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, poly A resin in which an ultraviolet absorber and / or a hard coat agent is added to a resin component such as sulfone or a cellulosic resin can be used. As the resin component for the hard coat, a vehicle resin for gravure ink and the like can also be suitably used. Specific examples thereof include, for example, nitrocellulose, ethyl cellulose, polyamide resin, vinyl chloride, chlorinated polyolefin, acrylic resin, and polyurethane. , Polyester and the like. These gravure ink vehicle resins include, for example, ester gum, dammar gum, maleic acid resin, alkyd resin, phenol resin, ketone resin, xylene resin, terpene resin, petroleum resin, etc. May be blended. Further, as the protective layer forming material, an adhesive composition obtained by adding an ultraviolet absorber and / or a hard coat agent to a thermosetting, photo-curing or electron beam-curing reactive adhesive can also be used. As the ultraviolet absorber, benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, oxalic anilide-based compounds, organic ultraviolet absorbers such as cyanoacrylate-based compounds, cesium oxide,
Inorganic ultraviolet absorbers such as 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 compounding ratio of the ultraviolet absorber in the protective layer is usually 0.1 to 20% by weight, preferably 0.5 to 10% by weight. Examples of the hard coating agent include organopolysiloxane-based, photo-curable resin-based acrylic oligomer-based, urethane acrylate-based, epoxy acrylate-based, polyester acrylate-based, thermosetting resin-based acryl-silicone-based, and inorganic materials such as ceramics. Compounds and the like can be used. 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 may be either a solventless type or a solvent type. In the protective layer forming material, besides an ultraviolet absorber and / or 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 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 polarization diffraction element. Further, a dye, a pigment, a surfactant and the like may be appropriately added to the adhesive as needed. The configuration of the hard coat layer can be a single hard coat layer or a composite layer according to 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 hard coat layer containing an inorganic compound, and the like are combined to form two layers. The composite layer composed of the above can be used as a 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, but when evaluated according to the test method described in JIS L0849, at least 3 or more is used as a criterion for discoloration. , Preferably four or more. For the formation of the UV-absorbing layer and the hard coat layer, which are protective layers, a conventional roll coating method, dipping method, gravure coating method, bar code method, spin coating method, spray coating method, printing method, etc. are applied as a film forming method. It is possible. When a protective layer composed of a composite layer of an ultraviolet absorbing layer and a hard coat layer is formed, for example, a method of applying a hard coating agent directly to the ultraviolet absorbing layer and forming the hard layer with an adhesive may be used. A method of laminating a coat layer and the like can be mentioned. The thickness of the protective layer cannot be determined unconditionally because it differs depending on the performance required for each of the ultraviolet absorbing property and the hard coating property, but is usually 0.1 to 100 μm.
m, 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 thus obtained polarization diffraction element of the present invention has a characteristic that the diffracted light has a circular polarization property, which is not available in the conventional optical member. Therefore, by using the polarization diffraction element of the present invention in a spectroscopic optical device that requires polarized light, such as an ellipsometer, the light use efficiency can be extremely increased. In conventional spectroscopic optical devices that require polarized light, the light emitted from the light source is separated for each wavelength using a spectral element such as a diffraction grating or prism, and then transmitted through a polarizer, or after transmitted through a polarizer. It needed to be split and a polarizer was essential. 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, but the polarization diffraction obtained by the manufacturing method of the present invention. By using the element, the light use efficiency is extremely high, and it is theoretically possible to use about 100%. Further, the polarization diffraction element obtained by the production method 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. However, in the polarization diffraction element obtained by the production method of the present invention, for example, diffracted light having right polarization can be completely blocked only when the left circularly polarizing plate is used. Due to having such characteristics, for example, in an environment where an observer observes a diffraction image through a polarizing plate, by changing the state of the polarizing plate, the diffraction image suddenly emerges from a dark field or suddenly disappears. Can be done. The polarization diffraction element obtained by the production method of the present invention has a very wide application range as an optical element with a diffraction function, and can be used as various optical elements, optoelectronic elements, decorative members, forgery prevention elements, and the like. . For example, as the above-mentioned second substrate, a triacetylcellulose film such as Fujitac (manufactured by Fuji Photo Film Co., Ltd.) or Konikatac (manufactured by Konica Corporation);
Transparent and isotropic films exemplified by PX film (manufactured by Mitsui Chemicals, Inc.), Arton film (manufactured by Nippon Synthetic Rubber Co., Ltd.), ZEONEX film (manufactured by Nippon Zeon), acrylene film (manufactured by Mitsubishi Rayon) By selecting, the polarization diffraction element of the present invention can be developed for various optical applications. For example, by providing the polarization diffraction element on various liquid crystal displays, 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, a linear polarizing plate can be obtained by combining it with a quarter-wave plate, thereby exhibiting an optical effect that has not been achieved as an optical element or an optoelectronic element. Further, the polarization diffraction element of the present invention can be used as a decorative member, and in this case, a new design property having a combination of a rainbow-coloring effect by diffractive power and a vivid coloration effect by cholesteric liquid crystal. Can be used as a film. Further, since the polarization diffraction element of the present invention can be made thin, the polarization diffraction element of the present invention on which a diffraction pattern having a design property is transferred is attached to a glass window or the like, or a glass window or the like is used as a second substrate at the time of transfer. Thereby, the selective reflection peculiar to the cholesteric liquid crystal accompanied with the diffraction pattern looks different colors depending on the viewing angle from the outside, and the fashionability is excellent. 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. Furthermore, the polarization diffraction element of the present invention can be used as a forgery prevention element in the form of a new forgery prevention film, a seal, a label or the like having both the forgery prevention effects of the diffraction element and the cholesteric liquid crystal. Specifically, as the second substrate at the time of transfer, 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. This makes it possible to integrate the polarization diffraction element with a card substrate, a mount, or the like, or to provide the polarization diffraction element partially, specifically, to attach, embed, or woven into paper. Therefore, when the polarization diffraction element obtained by the production method of the present invention is used as an element for preventing forgery, forgery of the polarization diffraction element is difficult, and more specifically, a region exhibiting diffractive ability is formed on the film surface. It can be said that it is extremely difficult to forge a cholesteric liquid crystal 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. For these reasons, the polarization diffraction element obtained by the production method of the present invention is very suitable as a forgery prevention element. These applications are only examples, and the polarization diffraction element obtained by the manufacturing method of the present invention has been conventionally used for various purposes in which a single diffraction element, a single cholesteric liquid crystal film in which a normal cholesteric alignment is fixed is used, and a new type. Since various optical effects can be exhibited, it can be applied to various uses other than the above-mentioned uses.

[0020]

According to the present invention, it is possible to manufacture a polarization diffraction element having a unique optical property that diffracted light exhibits circular polarization without performing complicated steps and processing.
Because of having such optical characteristics, the polarization diffraction element obtained by the manufacturing method of the present invention has a very wide range of application as a diffraction function element, for example, optical elements such as liquid crystal displays, optoelectronic elements, decorative materials, It can be suitably used as an optical member such as a forgery prevention element.

[0021]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. Example 1 Preparation of Compound (I) -a 4- (6 ) was added to 180 g of distilled and purified tetrahydrofuran.
-Acryloyloxyhexyloxy) benzoic acid 151.
3 g (518 mmol) and 1.5 g of 2,6-ditert-butyl-4-methylphenol were dissolved, and 70.1 g of diisopropylethylamine (543 mmo) was added thereto.
Prepare a solution to which l) has been added. While cooling a solution of 62.1 g (543 mmol) of methanesulfonyl chloride in tetrahydrofuran to −10 ° C. and stirring, the above solution was added dropwise over 30 minutes. 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. Then, a solution of 29.87 g (246 mmol) of methylhydroquinone in tetrahydrofuran was added dropwise to the reaction solution. Thereafter, the reaction solution was stirred for 15 minutes, and then 3.0 g of 4-dimethylaminopyridine (2 g) was added.
5mmol) with 62.4 g (617m) of triethylamine.
mol) was added dropwise over 15 minutes. 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 completion of the reaction,
The mixture was diluted with 00 ml of ethyl acetate, transferred to a separating funnel and then separated with 1N hydrochloric acid, and the organic layer was washed with 1N hydrochloric acid, a saturated aqueous solution of sodium hydrogen carbonate and a saturated aqueous solution of magnesium sulfate. The organic layer was dehydrated and dried by adding 100 g of anhydrous magnesium sulfate and stirring at room temperature for 1 hour. The magnesium sulfate was separated by filtration, and concentrated by a rotary evaporator to obtain methylhydroquinone bis (4-
(6-Acryloyloxy hexyloxy) benzoic acid)
The ester was obtained as a crude product. The crude product was recrystallized from ethyl acetate / methanol to give methylhydroquinone bis (4- (6-acryloyloxyoxyhexyloxy) benzoic acid) ester (compound (I) -a).
146.9 g were obtained as white crystals (yield 85.2).
%). The purity by GPC of this compound was 98.7%. GPC uses tetrahydrofuran as an elution solvent, and is a packed column for high-speed GPC (TSKgelG-100).
0HXL) equipped with Tosoh GPC analyzer CCP &
8000 (CP-8000, CO-8000, UV-8
000). When this compound was observed on a Mettler hot stage under a polarizing microscope, it turned into a crystalline phase at room temperature and a nematic phase at around 85 ° C., and became an isotropic phase at around 115 ° C. when further heated. Preparation of Compound (II) -a Using the same method as in the synthesis of Compound (I) -a, 4- (6
-Acryloyloxyhexyloxy) benzoic acid
5 g (111 mmol), 4-cyanophenol
From 6 g (106 mmol) to 34.8 g of 4-cyanophenol 4- (6-acryloyloxyohexyloxy) benzoate (compound (II) -a, yield 84)
%). The purity of this compound by GPC was 99.3.
%Met. Production of polarization diffraction element 7.0 g of the above compound (I) -a, compound (II)-
a, 1.07 g, chiral dopant liquid crystal S-811
1.93 g (manufactured by Roddick), 0.3 g of a photoreaction initiator Irgacure 907 (manufactured by Ciba Geigy) and 0.1 g of a sensitizer diethylthioxanthone were weighed and dissolved in 90 g of N-methyl-2-pyrrolidone. 1.5 mg of a fluorinated surfactant S-383 (produced by Asahi Glass) was added to this solution.
Was added. The above solution was applied using a bar coater on a polyethylene naphthalate film (manufactured by Mitsubishi Diafoil) whose surface was rubbed with rayon cloth.
After coating, the film is put into a clean oven set at 60 ° C., dried for 15 minutes, and then heat-treated in an oven set at 80 ° C. for 5 minutes, and then heated to about 1 ° C.
The cholesteric alignment of the liquid crystal layer was completed by cooling to 50 ° C./min. Crosslinking with ultraviolet light (UV) was performed at the same temperature to obtain a cholesteric liquid crystal film. U
A high-pressure mercury lamp was used as the V light source, and the irradiation intensity was 120
In W / cm ² , the integrated irradiation amount during the irradiation time of 10 seconds is 80
It was 0 mJ. The liquid crystal layer after irradiation was cured, and its surface hardness was about HB in terms of pencil hardness. The obtained cholesteric liquid crystal film has selective reflection light peculiar to cholesteric alignment when viewed obliquely. When a transmission spectrum is evaluated by a spectroscope V-570 (manufactured by JASCO Corporation), a selective reflection light near 780 nm is obtained. A reduced area of the transmitted light originating was observed. Then, 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 liquid crystal film were overlapped to face each other.
It was placed on a plate of a ton press, heated and pressed at 80 ° C. and 5 MPa, and held for 1 minute. Then, it was taken out from the press, and the scored type diffraction grating film was removed to obtain a polarization diffraction element. Observation of the cholesteric-aligned liquid crystal film surface on which the diffraction grating film of the obtained polarization diffraction element was superimposed revealed that iridescence caused by the diffraction pattern and selective reflection characteristic of the cholesteric liquid crystal were clearly observed.
Also, when the orientation state of the cholesteric liquid crystal 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. In addition, it was 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 cholesteric liquid crystal film. 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. The number of spiral turns of cholesteric orientation in this region was 4.
Also, He-N is vertically set in the cholesteric liquid crystal film surface.
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). As a result, iridescent diffracted light was observed. The brightness was almost the same as when observed without a polarizing plate. In contrast, observation through a left circularly polarizing plate (transmitting only left circularly polarized light) revealed a dark field, and no rainbow-color diffracted light was observed. From these results, it was confirmed that in the polarization diffraction element obtained, a region exhibiting diffractive ability was formed in the film surface region, and that the diffracted light was right circularly polarized light. Example 2 Preparation of Compound (III) -a 5.00 g (17.5 mmol) of (S)-(−)-1,1′-bi-2-naphthol (manufactured by Tokyo Chemical Industry, 99% ee of chiral purity), 4 −
8.96 g of n-octyloxybenzoic acid (35.8 mm
ol), a dichloromethane solution of dicyclohexylcarbodiimide (DCC, manufactured by Tokyo Chemical Industry) was added dropwise at 0 ° C., and the mixture was reacted at 0 ° C. for 1 hour, and then heated to room temperature for further 6 hours. The insoluble portion of the obtained reaction solution was separated by filtration, and the filtrate was washed with a saturated aqueous solution of ammonium chloride, dried over magnesium sulfate, and concentrated to obtain a crude esterified product. This was recrystallized with an acetone / methanol mixed system to obtain 11.2 g (yield 84%) of an ester as pale yellow crystals (compound (III) -a). Preparation of polarization diffraction element 7.0 g of compound (I) -a obtained in Example 1, 7.0 g of compound (II) -a, and the above compound (III) -a
0.5 g, Irgacure 907 photoinitiator (manufactured by Ciba Geigy) and 0.1 g of sensitizer diethylthioxanthone were weighed and dissolved in 90 g of N-methyl-2-pyrrolidone. This solution is added to a fluorine-based surfactant S-
383 (manufactured by Asahi Glass) was added in an amount of 0.05 mg. The above solution was applied using a spin coater on a polyethylene naphthalate film whose surface was rubbed with rayon cloth. After coating, the film was put into a clean oven set at 60 ° C. and dried for 15 minutes.
Heat treatment was performed in an oven set at 0 ° C. for 5 minutes, and the temperature was reduced to 50 ° C. at a rate of about 1 ° C./minute to complete the cholesteric alignment of the liquid crystal layer. Then, Example 1
Crosslinking was performed by UV irradiation to obtain a cholesteric liquid crystal film. The liquid crystal layer after irradiation was cured, and the surface hardness thereof was about HB to H in terms of pencil hardness. When the thickness of the liquid crystal layer of the cholesteric liquid crystal film was measured by a stylus type thickness gauge, it was 1.2 μm.
Cholesteric liquid crystal film has selective reflection light peculiar to cholesteric alignment of orange color even from the front,
When the transmission spectrum was evaluated using a spectroscope V-570 (manufactured by JASCO Corporation), a reduced region of transmitted light due to selective reflection was observed around a wavelength of 580 nm. The diffraction pattern was transferred in the same manner as in Example 1 to obtain a polarization diffraction element. Observation of the surface of the cholesteric liquid crystal film on which the diffraction grating film of the obtained polarization diffraction element was superimposed revealed clear iridescence caused by the diffraction pattern and selective reflection characteristic of the cholesteric liquid crystal. In addition, when the orientation state of the cholesteric liquid crystal 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, H is vertically set in the cholesteric liquid crystal film.
When an e-Ne laser (wavelength 632.8 nm) was incident, laser light was observed at an emission angle of 0 ° and about ± 35 °. Example 3 Methylhydroquinone bis (4- (9-acryloyloxynonyloxy) synthesized by the same method as in Example 1.
(Benzoic acid) ester (compound (I) -b) 7.8 g, 4
-Cyanophenol 4- (3-acryloyloxypropyloxy) benzoate (Compound (II) -b)
40 g of 2.2 g, 0.5 g of the binaphthol derivative (compound (III) -a) prepared in Example 2, 0.3 g of photoreaction initiator Irgacure 907 (manufactured by Ciba Geigy), and 0.1 g of sensitizer diethylthioxanthone Was dissolved in tetrachloroethane to prepare a solution. The above solution is applied using a die coater on a polyphenylene sulfide film (manufactured by Toray Industries Co., Ltd.) whose surface has been rubbed with a nylon-6 cloth, and the back surface of the film is attached to a soda lime glass substrate. 80 ℃
Was placed on a hot plate and dried for 20 minutes. The cholesteric alignment of the liquid crystal layer had already been completed. Thereafter, the film was put into an oven set at 50 ° C. in a state in which the film was in close contact with the glass substrate, UV irradiation was performed at that temperature, and the glass substrate was removed to obtain a cholesteric liquid crystal film. A high-pressure mercury lamp was used as the UV light source, the irradiation intensity was 120 W / cm ² , and the integrated irradiation amount during the irradiation time of 10 seconds was 800 mJ. The liquid crystal layer after irradiation was cured, and the surface hardness thereof was about HB to H in terms of pencil hardness. The obtained cholesteric liquid crystal film was obtained in Example 2.
The film had almost the same optical characteristics as the cholesteric liquid crystal film obtained in Example 2, and had a center of selective reflection at 585 nm. The thickness of the liquid crystal layer of the cholesteric liquid crystal film was measured with a stylus-type film thickness meter, and was 1.7.
μm. Edmund Scientific Japan Inc. ruled line diffraction grating film (900 / mm)
Is wound around a laminating roll of a laminator DX-350 manufactured by Tokyo Laminex and fixed at 150 ° C., 0.1 M
Under a condition of Pa and a roll contact time of 0.5 seconds, the film was heated and pressed in a direction in which the diffraction surface of the diffraction grating film was in contact with the liquid crystal surface of the cholesteric liquid crystal film. Observation of the surface of the cholesteric liquid crystal film on which the diffraction grating film was superimposed revealed that the rainbow color caused by the diffraction pattern and the selective reflection characteristic of the cholesteric liquid crystal were clearly observed. When the orientation state of the cholesteric liquid crystal film surface from which the diffraction grating film was removed was observed with a polarizing microscope and the cross section of the liquid crystal layer was observed with a transmission electron microscope, it was confirmed that the state was the same as in Example 2. Also, a He-Ne laser (wavelength 632.8 n
m), laser light was observed at an emission angle 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). As a result, iridescent diffracted light was observed. The brightness was almost the same as when observed without a polarizing plate. On the other hand, observation through a left circularly polarizing plate (transmitting only left circularly polarized light) revealed a dark field, and no rainbow-color diffracted light was observed. From these results, it was confirmed that in the cholesteric liquid crystal film, a region exhibiting diffractive ability was formed in the film surface region, and that the diffracted light was right circularly polarized light. Next, a commercially available adhesive made of a photocurable acrylic oligomer was applied to the cholesteric liquid crystal surface of the obtained cholesteric liquid crystal film using a bar coater to a thickness of 5 μm. Next, a triacetylcellulose film was adhered to the application surface with a desktop laminator, and irradiated with ultraviolet rays to cure the adhesive. After curing the adhesive, hold the end of the polyphenylene sulfide film used as the alignment support substrate when obtaining the cholesteric liquid crystal film by hand.
The polyphenylene sulfide film was peeled in the direction of 80 ° at the interface between the film and the cholesteric liquid crystal film. A laminated body in which a silicone-based varnish KR9706 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the exposed liquid crystal surface of the cholesteric liquid crystal film with a bar coater so as to have a thickness of 5 μm, and heated and cured to form a protective layer ( A silicone-based hard coat layer / cholesteric liquid crystal layer / adhesive layer / triacetyl cellulose film) was obtained. The obtained laminate maintained the iridescent coloration characteristic caused by the diffraction pattern and the selective reflection characteristic characteristic of the cholesteric liquid crystal. Further, when the orientation state and the polarization diffraction effect of the cholesteric liquid crystal layer constituting the laminate were observed, no change was observed from the state before the transfer and lamination.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G02B 5/18 G02B 5/18 F term (Reference) 2H049 AA12 AA40 AA64 BA03 BA24 BB61 BC05 BC09 BC22 4H027 BA02 BA13 BE06 4J011 AA05 AC04 QA03 QA35 QA46 SA21 SA22 SA31 SA34 SA41 SA42 SA51 SA52 SA61 SA64 UA01 VA01 WA10 4J100 AE75P AF11P BA15P BC43P CA01 CA31 HA53 JA32 JA39

Claims (3)

[Claims] 1. A compound represented by the following general formula (1)
(I) and a compound (II) represented by the following general formula (2)
After forming a cholesteric liquid crystal film by forming a film from a liquid crystal material containing a low-molecular compound having an optically active site and cross-linking the liquid crystal material in a state where the liquid crystal material is cholesterically aligned, A method for producing a polarization diffraction element for providing a region exhibiting diffraction ability to a liquid crystal film. Embedded image (In the general formulas (1) and (2), R ¹ , R ² and R ³
Each independently represents hydrogen or a methyl group, X represents hydrogen,
It represents one selected from the group consisting of chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group and a nitro group, and a, b and c each represent an integer of 2 to 12. ) 2. A compound (I) represented by the general formula (1):
When the weight ratio of the compound (II) represented by the general formula (2) is 99:
The content of the low molecular weight compound is in the range of 1 to 50:50 and the total amount of the compound (I) and the compound (II) is 100 parts by weight,
The method for manufacturing a polarization diffraction element according to claim 1, wherein the film is formed from a liquid crystal material in a range of 0.01 to 60 parts by weight. 3. The low molecular compound contained in the liquid crystal material is a compound represented by the following general formula (3) or (4):
3. The method for producing a polarization diffraction element according to claim 1, wherein the method is II). Embedded image (In the general formulas (3) and (4), R ⁴ represents hydrogen or a methyl group, d and e each represent an integer of 2 to 12, and Y is selected from the following (i) to (xxiv). One of the divalent groups shown below.) Here, Z in the above (i) and (ii) represents one selected from the group consisting of hydrogen, chlorine, bromine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group and a nitro group. Embedded image