JP2018116209A - Volume hologram laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a volume hologram laminate which has a volume hologram difficult to reproduce and has an excellent appearance of images.SOLUTION: A volume hologram laminate 10 according to the present invention includes: a volume hologram recording layer 1; and a rotator film 2 on the volume hologram recording layer 1, the volume hologram recording layer 1 having diffraction reflection peak wavelengths including the diffraction reflection peak wavelength at which the light rotating angle α of the rotator film 2 satisfies the range of 10°≤|α|≤80°.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a volume hologram laminate. In particular, the present invention relates to a volume hologram laminate that is difficult to duplicate a volume hologram and has a good image appearance.

  In order to ensure that a cash card, prepaid card, commuter pass, passbook, passport, identification card, product, etc. are genuine and not forged, a hologram capable of stereoscopic display is used.

  As a hologram used for the above purpose, for example, an embossed hologram in which an interference pattern is recorded as surface irregularities is known. In recent years, a volume hologram that records an interference pattern as a difference in refractive index inside the recording layer is used instead of an embossed hologram. The volume hologram has a higher manufacturing technique, the manufacturing apparatus is complicated and expensive, and the material is difficult to obtain compared to the embossed hologram. Therefore, forgery / alteration of volume holograms is generally difficult compared to forgery / alteration of embossed holograms.

  As described above, in order to replicate a volume hologram, advanced optical design technology and expensive equipment are required. From the volume photosensitive material side, the photosensitive material for replication is brought into close contact with the volume hologram as an original plate. By applying a so-called contact copy technique of irradiating laser light, it becomes possible to replicate a volume hologram.

  In order to prevent such duplication, for example, a technique of laminating a linear polarizing plate or a quarter wavelength plate on a volume hologram recording layer has been proposed (see, for example, Patent Document 1). However, according to the technique, since duplication is possible depending on conditions, illegal duplication cannot be completely prevented. That is, when linearly polarizing plates are laminated, sufficient diffraction light from the volume hologram recording layer can be obtained by making the vibration surface of the laser beam irradiated during contact copying perpendicular to the absorption axis of the linearly polarizing plate. Duplication is possible. Further, when the quarter wavelength plate is laminated, if the vibration surface of the irradiation laser light is parallel to the optical axis (slow axis or fast axis) of the quarter wavelength plate, The polarization state of the diffracted light from the volume hologram recording layer is the same, and replication is possible.

  In addition, a technique in which a linearly polarizing plate and a quarter wavelength plate are combined and laminated has been proposed (see, for example, Patent Document 2). Although illegal duplication can be prevented according to this technique, the volume hologram laminate itself appears dark under natural light or white light, and the appearance of an image (diffraction image) recorded on the volume hologram recording layer is impaired.

Japanese Patent No. 3342056 JP 2011-174978 A

  The present invention has been made in view of the above problems and situations, and a problem to be solved is to provide a volume hologram laminate in which volume hologram replication is difficult and the appearance of images is good.

As a result of studying the cause of the above problems and the like by the present inventors to solve the above problems, it is difficult to duplicate a volume hologram by laminating an optical rotator film having a specific optical rotation angle on the volume hologram recording layer. It was found that a volume hologram laminate having a good image appearance can be provided.
That is, the said subject which concerns on this invention is solved by the following means.

1. A volume hologram recording layer;
An optical rotator film laminated on the volume hologram recording layer,
The volume hologram laminate, wherein an optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 ° at at least one of diffraction reflection peak wavelengths of the volume hologram recording layer.

  2. The volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 ° at any diffraction reflection peak wavelength. 2. The volume hologram laminate according to item 1.

  3. The volume according to Item 1 or 2, wherein the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film is different for each diffraction reflection peak wavelength. Hologram laminate.

  4). The optical rotation angle α of the optical rotator film satisfies 25 ° ≦ | α | ≦ 65 ° in at least one of diffraction reflection peak wavelengths of the volume hologram recording layer. The volume hologram laminate according to any one of the above.

  5. The volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film satisfies 25 ° ≦ | α | ≦ 65 ° at any diffraction reflection peak wavelength. 5. The volume hologram laminate according to any one of items 1 to 4.

  According to the present invention, it is possible to provide a volume hologram laminate in which it is difficult to duplicate a volume hologram and the appearance of an image is good.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
When contact copying is attempted using the volume hologram laminate configured as described above as a master, linearly polarized laser light incident on the volume hologram laminate via the photosensitive material for duplication is rotated by the optical rotator film, and then the volume hologram The light enters the recording layer, is diffracted and reflected by the volume hologram recording layer, is rotated again by the optical rotator film, and then enters the photosensitive material for duplication. Therefore, the exposure light directly incident on the photosensitive material for replication and the reproduction light diffracted and reflected by the volume hologram laminate of the exposure light transmitted through the photosensitive material for replication do not interfere with each other. It is recognized that this is clearly different from the volume hologram recording layer according to the present invention. Moreover, when observing the volume hologram laminate of the present invention under natural light or white light, light of various polarizations enters the volume hologram laminate. For this reason, even if incident light is rotated by the optical rotator film, the image recorded on the volume hologram recording layer can be observed without impairing the appearance, and the appearance of the image can be improved.
In addition, when the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and optical rotator films having different rotation angles for each diffraction reflection peak wavelength of the volume hologram laminate are laminated, it is for duplication at the time of contact copying. The intensity of incident light on the photosensitive material differs for each diffraction reflection peak wavelength. As a result, color misregistration occurs in the image recorded on the obtained contact copy sample, and it becomes clearer that the image is a duplicate.

Schematic sectional view showing the configuration of the volume hologram of the present embodiment Schematic sectional view showing the structure of the optical rotatory film Wavelength dependence of refractive index of cholesteric liquid crystal layer of optical rotatory film

The volume hologram laminate of the present invention comprises a volume hologram recording layer and an optical rotator film laminated on the volume hologram recording layer, and at least one of the diffraction reflection peak wavelengths of the volume hologram recording layer, The optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 °. This feature is a technical feature common to or corresponding to each claim.
In the present invention, the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 ° at any diffraction reflection peak wavelength. Is preferred. Even when the volume hologram recording layer diffracts and reflects a plurality of wavelength regions, it is difficult to duplicate the volume hologram, and a volume hologram laminate having a good image appearance can be obtained.
In the present invention, it is preferable that the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film is different for each diffraction reflection peak wavelength. As a result, color deviation occurs in the image of the replicated product by contact copy and it becomes clear that the product is a replicated product, so that it becomes more difficult to replicate the volume hologram.
In the present invention, it is preferable that the optical rotation angle α of the optical rotator film satisfies 25 ° ≦ | α | ≦ 65 ° in at least one of the diffraction reflection peak wavelengths of the volume hologram recording layer. As a result, the difference between the volume hologram recording layer according to the present invention as the original plate and the replicated product by contact copy becomes more prominent, so that it becomes more difficult to replicate the volume hologram.
In the present invention, the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film is 25 ° ≦ | α | ≦ 65 ° at any diffraction reflection peak wavelength. It is preferable to satisfy. Even when the volume hologram recording layer diffracts and reflects a plurality of wavelength regions, the difference between the volume hologram recording layer according to the present invention as a master and a replica by contact copy becomes more prominent. It becomes more difficult.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit. Unless otherwise specified, measurements such as operation and physical properties are performed under conditions of room temperature (20 to 25 ° C.) and humidity of 40 to 50% RH.

<Outline of volume hologram laminate>
The volume hologram laminate of the present invention comprises a volume hologram recording layer and an optical rotator film laminated on the volume hologram recording layer, and at least one of the diffraction reflection peak wavelengths of the volume hologram recording layer, The optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 °.
In the present invention, the diffraction reflection peak wavelength refers to the wavelength at the position corresponding to the apex in the diffraction reflection light spectrum when the vertical axis is the diffraction reflection light intensity and the horizontal axis is the wavelength.

  A schematic configuration of the volume hologram laminate of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the volume hologram laminate of the present invention. As shown in FIG. 1, the volume hologram laminate 10 is configured by laminating an optical rotation film 2 on a volume hologram recording layer 1, and the optical rotation angle α of the optical rotation film 2 is determined by the diffraction of the volume hologram recording layer 1. At least one of the reflection peak wavelengths satisfies 10 ° ≦ | α | ≦ 80 °. Thus, when linearly polarized light enters the volume hologram laminate 10 from the optical rotator film 2 side, the light diffracted and reflected by the volume hologram recording layer 1 is rotated by the optical rotator film 2 and emitted. For this reason, if contact copying is performed on the volume hologram laminate 10, a volume hologram different from the volume hologram laminate 10 is duplicated as a contact copy sample. In addition, under natural light or white light, light of various polarizations is incident on the volume hologram laminate 10, so even if linearly polarized light among them is rotated, the appearance of the image is hardly affected. Appearance is good.

  The optical rotation angle α of the optical rotator film preferably satisfies 25 ° ≦ | α | ≦ 65 °. Thereby, the difference between the volume hologram recording layer according to the present invention as the original plate and the contact copy sample can be increased, and replication of the volume hologram can be made more difficult.

  The volume hologram recording layer may have a plurality of diffraction reflection peak wavelengths. In this case, at any diffraction reflection peak wavelength, the optical rotation angle α preferably satisfies 10 ° ≦ | α | ≦ 80 °, and more preferably satisfies 25 ° ≦ | α | ≦ 65 °. Thus, even when the volume hologram recording layer is diffracted and reflected in a plurality of wavelength bands, it is possible to obtain a volume hologram laminate in which the volume hologram is difficult to replicate and the image appearance is good.

  In addition, when the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, the optical rotation angles α are preferably different for each diffraction reflection peak wavelength. Thereby, a color shift is caused in the contact copy sample, and the difference between the volume hologram recording layer according to the present invention as the original plate and the contact copy sample can be increased.

  The volume hologram laminate configured as described above is adjacent so as to be in contact with both surfaces of the volume hologram recording layer or only one surface of the volume hologram recording layer from the viewpoint of holding and protecting the volume hologram recording layer. A layer may be provided. The adjacent layer is a layer containing a known resin having transparency. Specific examples of the resin include polyolefins such as polyethylene and polypropylene, acrylic resins such as polymethyl methacrylate, cellulose acylate, acetal resin, Examples include polycarbonate, polyurethane, and polyvinyl alcohol. Among these resins, cellulose acylate having excellent optical properties is preferable. These resins may be used alone or in combination of two or more.

  Hereinafter, a layer containing a polymerizable monomer before holographic exposure (interference exposure) is referred to as a photosensitive layer, and a layer in which a volume hologram is recorded by performing holographic exposure on the photosensitive layer is referred to as a volume hologram recording layer. Moreover, the polymer obtained by light-irradiating the photosensitive composition containing a polymerizable monomer, a photoinitiator, a matrix resin, its precursor, etc. and carrying out a polymerization reaction is called a photopolymer.

<Volume hologram recording layer>
The volume hologram recording layer is obtained, for example, by performing at least holographic exposure on a photosensitive layer obtained by applying and drying a photosensitive composition on a substrate (for example, a polyethylene terephthalate (PET) film). It is obtained by forming a diffraction grating composed of a high refractive index region and a low refractive index region.

  The photosensitive composition used for forming the volume hologram recording layer contains, for example, a matrix resin or a precursor thereof, a radical polymerizable monomer, a photo radical polymerization initiator, a sensitizer, a chain transfer agent, a solvent, and an additive. Do it.

(Radically polymerizable monomer)
The radically polymerizable monomer is not particularly limited as long as it has one or more radically polymerizable unsaturated double bonds in the molecule, but preferably has a relatively high refractive index. Examples of the radically polymerizable monomer include acrylamide, methacrylamide, methylenebisacrylamide, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, 2,3-dibromopropyl acrylate, Cyclopentanyl acrylate, dibromoneopentyl glycol diacrylate, 2-phenoxyethyl acrylate, 2-phenoxymethyl methacrylate, phenol ethoxylate monoacrylate, 2- (p-chlorophenoxy) ethyl acrylate, p-chlorophenyl acrylate, phenyl acrylate, 2-phenylethyl acrylate, 2- (1-naphthyloxy) ethyl acrylate o-biphenyl methacrylate, o-biphenyl acrylate, styrene, methoxystyrene, benzyl acrylate, phenyl acrylate, 2-phenylethyl acrylate, 2-phenoxyethyl methacrylate, phenol ethoxylate acrylate, methylphenoxyethyl acrylate, nonylphenoxyethyl acrylate, 2- Hydroxy-3-phenoxypropyl acrylate, phenoxypolyethylene glycol acrylate, 1,4-benzenediol dimethacrylate, 1,4-diisopropenylbenzene, 1,3,5-triisopropenylbenzene, benzoquinone monomethacrylate, 2- (1 -Naphthyloxy) ethyl acrylate, 2,3-naphthalenedicarboxylic acid (acryloxyethyl) monoester, Di (3-methacryloxy-2-hydroxypropyl) ether of phenolic acid, β-acryloxyethyl hydrogen phthalate, 2,2-di (p-hydroxyphenyl) propane diacrylate, 2,3-di (p-hydroxyphenyl) Propane dimethacrylate, 2,2-di (p-hydroxyphenyl) propane dimethacrylate, polyoxyethyl-2,2-di (p-hydroxyphenyl) propane dimethacrylate, bisphenol A epoxy diacrylate, bisphenol-A di ( 2-methacryloxyethyl) ether, ethoxylated bisphenol-A diacrylate, bisphenol-A di (3-acryloxy-2-hydroxypropyl) ether, bisphenol-A di (2-acryloxyethyl) ether, 2,2 Bis (4-acryloxyethoxyphenyl) propane, 2,2-bis (4-methacryloxyethoxyphenyl) propane, 2,2-bis (4-acryloxydiethoxyphenyl) propane, 2,2-bis (4- Methacryloxydiethoxyphenyl) propane, bis (4-acryloxydiethoxyphenyl) methane, bis (4-methacryloxydiethoxyphenyl) methane, 2-chlorostyrene, 2-bromostyrene, 2- (p-chlorophenoxy) Ethyl acrylate, tetrachloro-bisphenol-A di (3-acryloxy-2-hydroxypropyl) ether, tetrachloro-bisphenol-A di (2-methacryloxyethyl) ether, tetrabromo-bisphenol-A di (3- Methacryloxy-2-hydroxypropi ) Ether, tetrabromo-bisphenol-A di (2-methacryloxyethyl) ether, bis (4-acryloxyethoxy-3,5-dipromophenyl) methane, bis (4-methacryloxyethoxy-3,5-di) Promophenyl) methane, 2,2-bis (4-acryloxyethoxy-3,5-dibromophenyl) propane, 2,2-bis (4-methacryloxyethoxy-3,5-dibromophenyl) propane, bis (4 -Acryloxyethoxyphenyl) sulfone, bis (4-methacryloxyethoxyphenyl) sulfone, bis (4-acryloxydiethoxyphenyl) sulfone, bis (4-methacryloxydiethoxyphenyl) sulfone, bis (4-acryloxypropoxy) Phenyl-dibromophenyl) sulfone, bis (4-metac) Liloxypropoxypheny-dibromophenyl) sulfone, diethylenedithioglycol diacrylate, diethylenedithioglycol dimethacrylate, triphenylmethylthioacrylate, 2- (tricyclo [5.2.1.0 ^2,6 ] dibromodecylthio) ethyl acrylate, S- (1-naphthylmethyl) thioacrylate, an ethylenically unsaturated double bond oil-containing compound containing at least two S atoms in the molecule described in JP-A-2-247205 and JP-A-2-261808, N-vinylcarbazole, 2- (9-carbazolyl) ethyl acrylate, 2- [β- (N-carbazyl) propionyloxy] ethyl acrylate, 2-naphthyl acrylate, pentachlorophenyl acrylate, 2,4,6-tribromophenyl A Acrylate, 2- (2-naphthyloxy) ethyl acrylate, N-phenylmaleimide, p-biphenyl methacrylate, 2-vinylnaphthalene, 2-naphthyl methacrylate, 2,3-naphthalene dicarboxylic acid (2-acryloxyethyl) (3- Acryloxypropyl-2-hydroxy) diester, N-phenylmethacrylamide, t-butylphenyl methacrylate, diphenic acid (2-methacryloxyethyl) monoester, diphenic acid (2-acryloxyethyl) (3-acryloxypropyl- 2-hydroxy) diester, 4,5-phenanthrene dicarboxylic acid (2-acryloxyethyl) (3-acryloxypropyl-2-hydroxy) diester, and the like, but are not limited thereto.

  Examples of the radical polymerizable monomer include those having a 9,9-diarylfluorene skeleton and having at least one ethylenically unsaturated double bond in the molecule. Specifically, it is a compound having a structure represented by the following general formula (I).

In the general formula (I), R ₁ and R ₂ each independently represent a radical polymerizable group containing an acryloyl group or a methacryloyl group at the terminal. For example, the terminal has an acryloyl group or a methacryloyl group, and may be a group that can be bonded to the benzene ring in the above structure via an oxyethylene chain, an oxypropylene chain, a urethane bond, an amide bond, or a combination thereof. preferable.
In the general formula (I), X _{1 to} X ₄ each independently represent a hydrogen atom or a substituent. Examples of the substituent include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an amino group, a dialkylamino group, a hydroxy group, a carboxy group, and a halogeno group.

  Moreover, as a radically polymerizable monomer, for example, a urethane acrylate composed of a condensate of a phenyl isocyanate compound and a compound having a hydroxy group and an acryloyl group in one molecule can be used. Specifically, for example, compounds having structures represented by the following general formulas (II) to (IV) can be used.

In the general formulas (II) to (IV), each R independently represents a group having an ethylenically unsaturated bond. X independently represents a group having 2 to 40 carbon atoms and one or more oxygen atoms (present in the form of an ether bridge).
The group represented by X may be linear, branched or cyclic, and may be substituted with a functional group. In addition, the group represented by X is particularly preferably a linear or branched oxyalkylene or polyoxyalkylene group, respectively. The polyoxyalkylene group preferably has 1 to 10 oxyalkylene group repeating units, and more preferably has 1 to 8 oxyalkylene group repeating units.

  Furthermore, as the radical polymerizable monomer, a compound having a structure represented by the following general formula (V) can also be used.

In the general formula (V), R ^{1 to} R ⁵ are each independently a hydrogen atom, a halogeno group, an alkyl group having 1 to 6 carbon atoms, a trifluoromethyl group, an alkylthio group having 1 to 6 carbon atoms, or carbon. A C1-C6 alkylseleno group, a C1-C6 alkyltelluro group, or a nitro group is represented. R ⁶ and R ⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

  In the above general formula (V), A represents a linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkenyl group having 1 to 6 carbon atoms, or 2 to 6 ethylene oxides. Represents a polyalkylene oxide group having units or propylene oxide units.

  Among these radical polymerizable monomers, a monomer having a substituted or unsubstituted phenyl group, a monomer having a substituted or unsubstituted naphthyl group, a substituted or unsubstituted heterocyclic aromatic moiety having up to 3 rings A monomer having a chlorine atom, a monomer having a chlorine atom, or a monomer containing a bromine atom is preferable because its refractive index is relatively high.

  The above radical polymerizable monomers may be used alone or in combination of two or more.

  The content of the radical polymerizable monomer in the photosensitive composition is, for example, preferably in the range of 1 to 25% by mass, and more preferably in the range of 5 to 20% by mass.

(Photo radical polymerization initiator)
The photoradical polymerization initiator is an initiator that initiates photopolymerization of a radical polymerizable monomer by irradiation with laser light having a specific wavelength or light having excellent coherence in holographic exposure.

  Examples of the photo radical polymerization initiator include U.S. Pat. Nos. 4,766,055, 4,868,092, 4,965,171, JP-A Nos. 54-151024, 58-15503, and 58. -29803, 59-189340, 60-76735, JP-A-1-28715, JP-A-4-239505 and “Proceedings of Conference on Radiation Curing” -The publicly known radical photopolymerization initiators described in, for example, “PROCEEDINGS OF CONFERENCE ON RADIATION CURING ASIA” (pp. 461-477, 1988) can be used, but are not limited thereto.

  Specific examples of the radical photopolymerization initiator include, for example, diaryliodonium salts, 2,4,6-substituted-1,3,5-triazines (triazine compounds), azo compounds, azide compounds, organic peroxides, Examples thereof include organoborates, onium salts, halogenated hydrocarbon derivatives, titanocene compounds, monoacylphosphine oxides, bisacylphosphine oxides, and combinations of bisacylphosphine oxides and α-hydroxyketones. Moreover, the radical photopolymerization initiator system by combined use of hydrogen donors, such as a thiol compound, and a bisimidazole derivative can also be utilized. These radical photopolymerization initiators may be used alone or in combination of two or more.

  The content of the photo radical polymerization initiator in the photosensitive composition is preferably in the range of 0.05 to 50 parts by mass, for example, with respect to 100 parts by mass of the radical polymerizable monomer, and 0.1 to 30 parts by mass. More preferably within the range of parts.

(Sensitizer)
The photosensitive composition may contain a sensitizer having a sensitizing function with respect to the radical photopolymerization initiator. Such a sensitizer has an absorption maximum wavelength in the range of 400 to 800 nm, particularly 450 to 700 nm. These sensitizers absorb light having a wavelength in the above range, thereby causing a sensitizing action on the radical photopolymerization initiator.

  Examples of such a sensitizer include polymethine compounds such as cyanine dyes and styryl dyes, xanthene compounds such as rhodamine B, rhodamine 6G, and pyronin GY, phenazine compounds such as safranin O, cresyl violet, Phenoxazine compounds such as brilliant cresyl blue; phenothiazine compounds such as methylene blue and new methylene blue; Examples thereof include a reel methane compound, a (thio) pyrylium salt compound, a squarylium compound, a coumarin dye, a thioxanthene dye, an acene dye, a merocyanine dye, and a thiazolium dye. These sensitizers may be used alone or in combination of two or more.

  When using a sensitizer, it is preferable that content of the sensitizer in a photosensitive composition exists in the range of 1-2000 mass parts with respect to 100 mass parts of radical photopolymerization initiators, for example, 20-20. More preferably, it is in the range of 1500 parts by mass.

(Chain transfer agent)
The photosensitive composition may contain a chain transfer agent. The chain transfer agent is not particularly limited, and a known radical chain transfer agent can be used.

  Examples of the chain transfer agent include n-butyl mercaptan, t-butyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, 5-chloro-2-mercaptobenzothiazole, 6-ethoxy-2-mercapto. Examples include benzothiazole. In addition, other heterocyclic mercaptans such as 2,4,6-trimercapto-s-triazine and 2,4,6-trimercapto-1,3,5-triazine; tetramethylthiudium disulfide, tetraethylthiu Disulfides such as radium disulfide; halogen compounds such as carbon tetrachloride and carbon tetrabromide; olefins such as 2-methyl-1-butene and α-methylstyrene dimer; and the like. These chain transfer agents may be used alone or in combination of two or more.

  When the chain transfer agent is used, the content of the chain transfer agent in the photosensitive composition is preferably in the range of 0.05 to 50 parts by mass with respect to 100 parts by mass of the radical polymerizable monomer, for example, 0 More preferably, it is in the range of 1 to 30 parts by mass.

(Matrix resin or its precursor)
The photosensitive composition may contain a matrix resin or a precursor thereof. The matrix resin has a function of improving the volume hologram thickness uniformity, heat resistance, mechanical properties, and the like, and stabilizing the volume hologram formed by holographic exposure. Further, at the time of forming a volume hologram, it may have a function of not inhibiting or efficiently expressing the diffusion transfer phenomenon of the polymerizable monomer or photopolymer.

  As the matrix resin, for example, any of thermoplastic resins, thermosetting resins, active energy ray curable resins, and the like can be used without limitation. In addition, those resins modified with a polysiloxane chain or a perfluoroalkylene chain can also be used. These matrix resins may be used alone or in combination of two or more.

  Examples of matrix resins include, for example, polyvinyl acetate, polyvinyl butyrate, polyvinyl formal, polyvinyl carbazole, polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polybutyl acrylate, polymethacrylonitrile, polyethyl methacrylate, polybutyl methacrylate. , Polyacrylonitrile, poly-1,2-dichloroethylene, ethylene-vinyl acetate copolymer, syndiotactic polymethyl methacrylate, poly-α-vinyl naphthalate, polycarbonate, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polystyrene , Poly-α-methylstyrene, poly-o-methylstyrene, poly-p-methylstyrene, poly-p-phenyl Styrene, poly-2,5-dichlorostyrene, poly-p-chlorostyrene, poly-2,5-dichlorostyrene, polyarylate, polysulfone, polyether, polyethersulfone, styrene-acrylonitrile copolymer, styrene-divinyl Benzene copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, ABS resin, polyethylene, polyvinyl chloride, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyvinyl pyrrolidone, polyvinylidene chloride, Hydrogenated styrene-butadiene-styrene copolymer, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene, hexafluoroethylene and vinyl alcohol, vinyl Copolymer with ester, vinyl ether, vinyl acetal vinyl butyral, etc., Copolymer of (meth) acrylic acid cycloaliphatic ester and methyl (meth) acrylate, polyvinyl acetate, methyl methacrylate-ethyl acrylate-acrylic acid copolymer Examples include coalescence.

  When the matrix resin or its precursor is used, the content of the matrix resin or its precursor in the photosensitive composition is preferably in the range of 1 to 30% by mass, for example, in the range of 5 to 27% by mass. More preferably, it is within.

(solvent)
The photosensitive composition may contain a solvent as needed in order to apply the photosensitive composition. However, when the photosensitive composition contains a component that is liquid at room temperature, the solvent may not be contained.

  Examples of the solvent include aliphatic solvents such as n-pentane, n-hexane, n-heptane, n-octane, cyclohexane and methylcyclohexane; ketone solvents such as methyl ethyl ketone, acetone and cyclohexanone; diethyl ether and isopropyl ether. , Tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, anisole, phenetol, and other ether solvents; ethyl acetate, butyl acetate, ethylene glycol diacetate, and other ester solvents Aromatic solvents such as toluene and xylene; methyl cellosolve, ethyl cellosolve, butyl Cellosolve solvents such as Rosolve; Alcohol solvents such as methanol, ethanol, propanol and isopropyl alcohol; Ether solvents such as tetrahydrofuran and dioxane; Halogen solvents such as dichloromethane and chloroform; Nitrile solvents such as acetonitrile and propionitrile; Examples include polar solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N, N-dimethylformamide, and N, N-dimethylacetamide. These solvents may be used alone or in combination of two or more.

(Additive)
The photosensitive composition is optionally made of a plasticizer, a compatibilizer, a polymerization inhibitor, a surfactant, a silane coupling agent, an antifoaming agent, a release agent, a stabilizer, an antioxidant, a flame retardant, an optical Additives such as brighteners and ultraviolet absorbers may be further included.

(Method for producing photosensitive composition)
The photosensitive composition can be obtained by mixing the above-described components all at once or sequentially. As an apparatus used when mixing, stirring or mixing apparatuses, such as a magnetic stirrer, a homodisper, a quick homomixer, a planetary mixer, are mentioned, for example. The obtained photosensitive composition may be used after being filtered, if necessary.

<< Method for producing volume hologram recording layer >>
The method for producing the volume hologram recording layer is not particularly limited, but holographic exposure is performed on a coating film (photosensitive layer) obtained by applying the above-described photosensitive composition to a separately prepared substrate and drying it. The method of performing is mentioned.

(Formation of photosensitive layer)
The formation method in particular of a photosensitive layer is not restrict | limited, For example, the method of drying after apply | coating the photosensitive composition on the base material prepared separately, etc. are mentioned. Examples of the base material include acrylic resin, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthoate, polyethylene, polypropylene, amorphous polyolefin, cellulose acetate, hydrated cellulose, cellulose nitrate, cycloolefin polymer, polystyrene, polyepoxide, polysulfone, Examples of the resin base material include cellulose acylate, polyamide, polyimide, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, and polydicyclopentanediene.

  In addition, as another method for forming the photosensitive layer, a method in which the photosensitive composition is directly applied on the above-described adjacent layer and dried is also exemplified. In this method, the formation of a diffraction grating can be promoted to the interface with the adjacent layer within the photosensitive layer by appropriately selecting an adjacent layer that is easily adhered to the photosensitive layer.

  As a method for applying the photosensitive composition on the adjacent layer or the substrate, a conventionally known method can be used, and specific examples include a spray method, a spin coating method, a wire bar method, a dip coating method, Examples thereof include an air knife coating method, a roll coating method, a blade coating method, and a doctor roll coating method.

  As a method for drying the applied photosensitive composition, for example, various conventionally known methods using a hot plate, an oven, a belt furnace or the like can be employed. The drying temperature is not particularly limited and is, for example, in the range of 10 to 80 ° C., and the drying time is not particularly limited, and is in the range of 1 to 60 minutes, for example.

  What is necessary is just to set suitably the layer thickness of a photosensitive layer so that it may become the preferable layer thickness (Preferably within the range of 5-100 micrometers, More preferably within the range of 5-50 micrometers) of the volume hologram recording layer mentioned later.

(Volume hologram recording method: formation of volume hologram recording layer)
The method of performing holographic exposure on the photosensitive layer, recording (writing) a volume hologram, and forming the volume hologram recording layer is not particularly limited, and examples thereof include the following methods.

First, when recording information, light capable of causing a chemical change of the polymerizable monomer, that is, polymerization and concentration change, is used as recording light (also referred to as object light).
For example, when recording information as a volume hologram, object light is irradiated onto the photosensitive layer together with reference light so that the object light and reference light interfere with each other in the photosensitive layer. As a result, the interference light causes polymerization and concentration change of the polymerizable monomer in the photosensitive layer. As a result, the interference fringes cause a refractive index difference in the photosensitive layer, and the interference fringes recorded in the photosensitive layer A volume hologram is recorded.

  As the recording light used for recording the volume hologram, a visible light laser excellent in coherence is preferably used. For example, an argon ion laser (emission wavelength: 458 nm, 488 nm, 514 nm), a krypton ion laser (emission wavelength: 647. 1 nm), helium-neon laser (emission wavelength: 633 nm), YAG laser (emission wavelength: 532 nm), or the like can be used.

The irradiation energy amount (exposure amount) at the time of volume hologram recording is not particularly limited, but is preferably in the range of 10 to 250 mJ / cm ² , for example.

  Further, examples of the volume hologram recording method include a polarization collinear volume hologram recording method, a reference light incident angle multiplexing type volume hologram recording method, and the like, and any recording method can provide good recording quality.

After recording the volume hologram, the volume hologram recording layer can be further subjected to appropriate treatments such as full exposure with ultraviolet rays and heating in order to promote refractive index modulation and complete (fix) the polymerization reaction. As a light source used for the entire surface exposure, for example, a light source emitting ultraviolet rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a carbon arc lamp, a xenon arc lamp, a metal halide lamp, or the like can be used. For example, the irradiation energy amount in the case of performing the entire surface exposure with ultraviolet rays is preferably in the range of 50 to 200 J / cm ² . Moreover, as temperature in the case of performing heat processing, the inside of the range of 50-150 degreeC is preferable, for example, and as processing time, the inside of the range of 30 minutes-3 hours is preferable, for example.

  When performing both the whole surface exposure and the heat treatment, the order is not particularly limited, and the whole surface exposure may be performed first, or the heat treatment may be performed first.

  From the viewpoint of durability, the thickness of the volume hologram recording layer is preferably in the range of 5 to 100 μm, and more preferably in the range of 5 to 50 μm.

<Reproduction method of volume hologram>
When reproducing (reading out) information recorded on the volume hologram recording layer, predetermined reproduction light (usually reference light) is irradiated to the volume hologram recording layer. The irradiated reproduction light is diffracted according to the interference fringes in the hologram recording layer. Since this diffracted light contains the same information as the volume hologram recorded on the volume hologram recording layer, the information recorded on the volume hologram recording layer is reproduced by reading the diffracted light with an appropriate detection means. be able to. Note that the wavelength regions of the object light, the reproduction light, and the reference light are arbitrary depending on the application, and may be in the visible light region or the ultraviolet light region.

《Optical Rotator Film》
The optical rotatory film according to the present invention is a film for rotating incident linearly polarized light in a specific wavelength range at an optical rotation angle α and emitting it as different linearly polarized light, and the optical rotation angle α is 10 ° ≦ | α | ≦ 80. Meet °.

The optical rotatory film includes at least a liquid crystal layer made of cholesteric liquid crystal. When the first linearly polarized light is incident on the liquid crystal layer, the light is converted into second linearly polarized light having a polarization plane different from that of the first linearly polarized light.
As a result, the light having a specific wavelength incident on the optical rotator film is rotated and emitted at a desired optical rotation angle, and depending on the wavelength of the incident light, it is emitted as it is without being rotated. (Wave rotation angle α = 0 °), and wavelength dependence of emission at different rotation angles can be realized.

The cholesteric liquid crystal exhibits selective reflection having a reflection center wavelength λ based on the helical period of the cholesteric liquid crystal. In addition, the wavelength of light that has a reflection band in either the clockwise circularly polarized light or the counterclockwise circularly polarized light that is diffracted and reflected by the volume hologram recording layer is longer than the reflection band of the optical rotator film. Preferably it is on the side.
This makes it possible to take advantage of the difference between the refractive index wavelength dependency of circularly polarized light incident in the clockwise direction of cholesteric liquid crystal and the refractive index wavelength dependency of circularly polarized light incident in the counterclockwise direction, and diffractive reflection of linearly polarized light of a specific wavelength. Not only the light is rotated and emitted with a fixed angle of rotation, but also diffracted and reflected light of linearly polarized light having different wavelengths is emitted by controlling the angle of rotation α or without changing the polarization state ( (Optical rotation angle α = 0 °) can be emitted, and an optical rotatory film with good controllability can be obtained.

FIG. 2 is a schematic configuration diagram showing the configuration of the optical rotatory film 2 according to this embodiment. As shown in FIG. 2, the optical rotatory film 2 includes an alignment film 22 and a cholesteric liquid crystal layer 23.
The alignment film and the cholesteric liquid crystal layer constituting the optical rotatory film will be described below.

(Alignment film)
The alignment film aligns the cholesteric liquid crystal contained in the cholesteric liquid crystal layer. As the alignment film, for example, a rubbed substrate, a known photo-alignment film, a stretched film, or the like can be used. In addition, the alignment film may be provided on both surfaces of the cholesteric liquid crystal layer.

  As a base material used as the alignment film, one having transparency is preferable. For example, a plastic film produced by stretching can be used. The stretched film includes uniaxially stretched and biaxially stretched films depending on the stretching method. Examples of the material of the film include cellophane, polycarbonate (PC), polyethylene (PE), polypropylene (PP), polyolefin (PO), ethylene vinyl alcohol (EVOH), polyvinyl alcohol (PVA), polyvinyl chloride, and polyethylene. Examples thereof include naphthalate (PEN), polyethylene terephthalate (PET), nylon, acrylic resin, and triacetyl cellulose (TAC) film.

(Cholesteric liquid crystal layer)
The cholesteric liquid crystal layer is a layer configured to contain cholesteric liquid crystals. The cholesteric liquid crystal contained in the cholesteric liquid crystal layer is a compound having a cholesteric structure or having a cholesteric structure under a temperature condition or the like, and is not particularly limited, and a known cholesteric liquid crystal forming compound can be used. is there.

  For example, as cholesteric liquid crystal forming compounds, conventionally known acyl derivatives of hydroxyalkyl cellulose, cholesteric liquid crystal forming polypeptides, cholesteric liquid crystal forming aromatic polyesters, polycarbonates, aromatic polyester imides, aromatic polyamides Main chain type polymer liquid crystal forming compounds such as poly (meth) acrylate, polymalonate, polysiloxane, etc., and chiral materials are mixed with them. Thus, a cholesteric liquid crystal can be used.

  Examples of the hydroxyalkyl cellulose used for producing the acyl derivative of hydroxyalkyl cellulose include hydroxypropyl cellulose, hydroxybutylated hydroxypropyl cellulose, and the like.

  As a cholesteric liquid crystal forming compound, it is necessary to introduce a flexible molecular chain into the side chain of the rigid cellulose molecule main chain part, in order to control the side chain length, flexibility, rigidity, etc. Various acyl derivatives are used. For example, esters of aliphatic, alicyclic and aromatic carboxylic acids having about 1 to 30 carbon atoms are preferred. For example, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, 2-methylbutyric acid, trimethylacetic acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, lauric acid, palmitic acid , Esters of saturated carboxylic acids such as stearic acid and isostearic acid, esters of alicyclic carboxylic acids such as cyclohexanecarboxylic acid, cyclohexylacetic acid, cyclohexanepropionic acid, cyclohexanebutyric acid, benzoic acid, phenylacetic acid, 3-phenylpropionic acid Preferred are esters of aromatic carboxylic acids such as 5-phenylvaleric acid and 4-phenylbutyric acid, and esters of unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid and itaconic acid.

  In addition, the properties and behaviors differ depending on the degree of esterification. Therefore, a fully esterified product and a partially esterified product are used as a compound design. In addition, unsaturated carboxylic acid esters can cause a curing (polymerization) reaction with an energy ray-curable compound used in combination with a liquid crystal compound. Therefore, it is also an effective method to use a part of the saturated carboxylic acid, for example, 0.1 to 20% by mass, for the purpose of crosslinking, with the unsaturated carboxylic acid.

  Preferred cholesteric liquid crystal forming compounds include, for example, hydroxypropylcellulose acetate, hydroxypropylcellulose propionate, hydroxybutylated hydroxypropylcellulose acetate, hydroxybutylated hydroxypropylcellulose propionate, hydroxybutylcellulose Acetic acid ester, hydroxybutyl cellulose propionate, etc., hydroxypropyl cellulose acrylic acid ester, hydroxypropyl cellulose methacrylic acid ester, hydroxybutylated hydroxypropyl cellulose acrylic acid ester, hydroxybutylated hydroxypropyl cellulose methacrylic acid ester , Hydroxybutylcellulose acrylic ester, Fully esterified products and partially esterified products such as methacrylic acid ester of droxybutylcellulose, hydroxypropylcellulose acetate-methacrylic acid ester, hydroxypropylcellulose propionate-methacrylic acid ester, hydroxybutylated hydroxypropylcellulose propionic acid Examples thereof include ester-methacrylic acid ester, hydroxybutyl cellulose propionate-methacrylic acid ester, and the like.

  As the cholesteric liquid crystal forming compound that can be used in the present invention, a conventionally known low molecular weight and medium molecular weight cholesteric liquid crystal forming compound can be used alone or in combination with the above-described high molecular weight cholesteric liquid crystal forming compound. can do. By mixing a chiral material with these cholesteric liquid crystal forming compounds, a chiral cholesteric liquid crystal is obtained.

  The chiral material used in the present invention is a material that dissolves in a nematic liquid crystal to develop a cholesteric liquid crystal phase, and a conventionally known material can be appropriately selected and used.

  In addition, in order to fix the helical pitch, i.e., color tone, of the cholesteric liquid crystal molecules in the helical structure, a method of rapidly cooling and vitrifying after applying the cholesteric liquid crystal on the substrate, a method of drying and solidifying the solution There is a method of fixing by irradiating energy. In the present invention, known methods can be appropriately selected and used for the cholesteric liquid crystal alignment method and the helical pitch fixing method.

Moreover, the helical pitch length can be adjusted by bringing a substance containing a solvent having an affinity for cholesteric liquid crystal into contact with the cholesteric liquid crystal region.
Examples of the solvent having an affinity for the cholesteric liquid crystal include methyl ethyl ketone, toluene, tetrahydrofuran, ethyl acetate, cyclohexanone, cyclopentanone, dimethylacetamide and the like.
In addition, as a substance containing a solvent having an affinity for cholesteric liquid crystal, for example, an ink obtained by dissolving vinyl chloride, acrylic, vinyl chloride copolymer, ethylene vinyl acetate copolymer or the like in the above solvent can be used.

  Further, when a chiral agent is intervened in the cholesteric liquid crystal molecule, the effect of shortening the helical pitch length can be obtained.

  In order to obtain the desired reflection band and optical rotation angle at the stage where the solvent etc. is no longer volatilized, the spiral pitch is taken into consideration that the solvent etc. volatilizes and the reflection band and optical rotation angle change. It is necessary to perform a process of fixing the length. That is, after the cholesteric liquid crystal is semi-cured and the reflection band and optical rotation angle are fixed, the cholesteric liquid crystal is contacted with a substance having an affinity for the cholesteric liquid crystal, and the helical pitch length of the cholesteric liquid crystal is further changed to obtain a desired reflection band and optical rotation angle. can do.

Further, as a method for adjusting the reflection band and the optical rotation angle of the cholesteric liquid crystal, there is a method using a substance that is permeable to the cholesteric liquid crystal. In the case of using a chiral material as a material that is permeable to the cholesteric liquid crystal, it is necessary to examine in advance whether or not the cholesteric liquid crystal state can be maintained.
As the permeable substance penetrates into the cholesteric liquid crystal, the reflection band and the optical rotation angle change. When the desired reflection band and optical rotation angle are reached, it is necessary to fix the reflection band and optical rotation angle. The method is preferably a method in which an energy ray-curable compound is added to the cholesteric liquid crystal and cured by irradiating energy rays when the desired reflection band and optical rotation angle are reached. Usually, it is convenient to use ultraviolet rays as the energy rays.

  There is no restriction | limiting in particular in the energy beam curable compound added to a cholesteric liquid crystal, A conventionally well-known energy beam curable compound can be used. In particular, it is preferable to contain a monomer, oligomer and / or polymer having 2 or more energy ray-curable groups in the molecule.

In the cholesteric liquid crystal, the wavelength λ of incident light has the same degree as the product of the helical pitch length P in the helical structure of the liquid crystal molecules (the length per pitch of the molecular helix of the liquid crystal molecules) and the refractive index n of the cholesteric liquid crystal. In the case of the incident light parallel to the helical axis direction, the circularly polarized light having the same rotational direction as the twist direction of the liquid crystal molecules is substantially reflected, and the circularly polarized light having the opposite rotational direction is substantially transmitted. Have The center wavelength of the wavelength band showing reflection characteristics lambda _{0 (hereinafter.} Referred to the selective reflection wavelength), the helical pitch length P, the liquid crystal of the ordinary refractive index n _o, the extraordinary refractive index When n _e following formula ( 1). The reflection bandwidth Δλ is expressed by the following formula (2). Hereinafter, (λ ₀ ± Δλ / 2) is defined as a reflection wavelength band.
Formula (1): λ ₀ = (n _o + n _e ) · P / 2
Expression (2): Δλ = (n _e −n _o ) · P

  Therefore, when light in the reflected wavelength band is circularly polarized light that travels in a direction parallel to the direction of the helical axis of the liquid crystal molecules and has the same rotational direction as the twist direction of the liquid crystal molecules, the cholesteric liquid crystal layer acts as a reflective film. . The reflectance in the reflection wavelength band depends on the number of helical pitches in the cholesteric liquid crystal layer. The number of helical pitches is represented by the number of rotations of liquid crystal molecules. When the spiral pitch number exceeds 10 revolutions, the reflectance is almost uniformly high in the reflection wavelength band without depending on the layer thickness of the cholesteric liquid crystal layer.

FIG. 3 is a schematic diagram showing the wavelength dependence of the refractive index of the cholesteric liquid crystal layer. In FIG. 3, n _R (λ) indicates the refractive index for clockwise circularly polarized light having the wavelength λ, and n _L (λ) indicates the refractive index for counterclockwise circularly polarized light having the wavelength λ. The twist direction of the liquid crystal molecules in the cholesteric liquid crystal layer may be clockwise or counterclockwise toward the light traveling direction. Hereinafter, as an example, the twist direction of the liquid crystal molecules is directed toward the light traveling direction. Will be described as being clockwise.

As shown in FIG. 3, when clockwise circularly polarized light enters the cholesteric liquid crystal layer, the change in the refractive index increases in the vicinity of the reflection wavelength band. On the other hand, since there is no reflection wavelength band for counterclockwise circularly polarized light, large refractive index fluctuations do not occur.
Here, when the refractive index for clockwise circularly polarized light of wavelength λ is n _R (λ) and the refractive index for counterclockwise circularly polarized light is n _L (λ), circularly polarized refractive index anisotropy Δn (λ) = | N _R (λ) −n _L (λ) | At this time, it has Δn (λ) which is not 0 in the vicinity of the reflection wavelength band. In addition, Δn (λ) is smaller than that in the vicinity of the reflection wavelength band at wavelengths far away from the reflection wavelength band. When light having a wavelength at which Δn (λ) is almost 0 is incident, the refractive index is different due to circular polarization. The directionality does not appear and the optical rotation is lost. This reflection wavelength band can be controlled by adjusting the helical pitch length P as described above. That is, a nematic liquid crystal having asymmetric carbon or a cholesteric liquid crystal is formed by adding a chiral agent to the nematic liquid crystal, and the reflection wavelength band can be determined by adjusting the addition amount of the chiral agent.

  In this way, in the reflection wavelength band shown in FIG. 3, since the circularly polarized light that matches the twist direction of the liquid crystal molecules is reflected and the transmittance is greatly reduced, the light transmitted through the cholesteric liquid crystal mainly has this twist direction. It becomes the reversely polarized light. Therefore, when linearly polarized light having a wavelength within the reflection wavelength band is incident, circularly polarized light is emitted instead of linearly polarized light, and the transmittance is further reduced to about half. Therefore, if the wavelength of the incident light is within the reflection wavelength band, the function as an optical rotator cannot be obtained. Therefore, by adjusting the chiral agent, the reflection wavelength band is set so that the wavelength of the incident light does not enter. good.

Therefore, the value of Δn (λ) can be adjusted by setting the wavelength of incident light to a value that avoids the reflection wavelength band. For example, the two wavelengths λ _a and λ _b (λ _a <λ _b ) are set to the shorter wavelength side and the longer wavelength side than the reflection wavelength band, respectively. Moreover, setting the wavelength lambda _a value that causes a Δn (λ _a)> 0, set the wavelength lambda _b to a value that causes a Δn (λ _b) ≒ 0. Thus, when the thickness d of the cholesteric liquid crystal layer, [Delta] n (lambda _a) ([Delta] n in lambda _a) is represented by the following formula (3). In the following formula (3), m represents 0 or a positive integer.
Formula (3): Δn (λ _a ) · d = (2m + 1) · λ _a / 2

By setting the [Delta] n (lambda _a) and the layer thickness d so as to satisfy the equation (3), linearly polarized light of the polarization plane perpendicular to the plane of polarization of linearly polarized light of the incident wavelength lambda _a it is emitted. On the other hand, linearly polarized light of wavelength lambda _b is for Δn (λ _b) ≒ 0, the unchanged polarization state of the incident linearly polarized light (optical rotation angle α = 0 °) is emitted. Equation (3) is a condition for making the polarization states of incident light and outgoing light substantially orthogonal (optical rotation angle α = 90 °), but by adjusting the value of the layer thickness d, an arbitrary optical rotation angle is obtained. The light rotated by α can be emitted.

  The optical rotation angle α of the optical rotatory film can be measured using, for example, a polarimeter P-2100 manufactured by JASCO Corporation.

《Other constituent layers》
In addition to the volume hologram recording layer and the optical rotator film, the volume hologram laminate of the present embodiment includes other layers such as a protective layer, a reflection layer, an antireflection layer, an ultraviolet absorption layer, and a photocurable adhesive layer. May be.

  The protective layer is a layer for preventing an influence such as deterioration in storage stability of the volume hologram recording layer. There is no restriction | limiting in the specific structure of a protective layer, It is possible to apply a well-known thing arbitrarily. For example, a layer made of a water-soluble polymer, an organic material, an inorganic material, or the like can be formed as the protective layer. The formation position of the protective layer is not particularly limited, and may be, for example, the surface of the volume hologram recording layer (between the volume hologram recording layer and the optical rotator film, or the opposite side of the volume hologram recording layer to the optical rotator film. Or may be formed between an adjacent layer and a support described later, or may be formed on the outer surface side of the support. From the viewpoint of protecting the volume hologram recording layer, the protective layer is preferably formed at a position closer to the volume hologram recording layer.

  The antireflection layer is a layer that improves the light use efficiency. The antireflection layer is provided on the side on which the object light and reproduction light of the volume hologram laminate are incident and output, or between the volume hologram laminate and the adjacent layer. A conventionally well-known thing can be suitably applied as an antireflection layer.

  The ultraviolet absorbing layer is formed on the outer surface of the adjacent layer, for example, and is used for cutting ultraviolet rays to the volume hologram recording layer. As the ultraviolet absorbing layer, conventionally known materials can be used as long as they have necessary strength and durability.

  The photocurable adhesive layer is a layer in which an adhesive cured film is formed by curing an adhesive that is cured with ultraviolet rays or visible light for adhesion between adjacent layers. Examples of the adhesive include urethane acrylate, acrylic monomer, photopolymerization initiator, and photosensitizer. Examples of the urethane acrylate include 2-isocyanatoethyl (meth) acrylate and 1,1-bis (acryloyloxymethyl) ethyl isocyanate. Examples of the acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, and 5-hydroxycyclooctyl. (Meth) acrylate, 1,3-butanediol (meth) acrylate, 1,4-butanediol (meth) acrylate, 1,6-hexanediol (meth) acrylate, 3-methylpentanediol (meth) acrylate, etc. These may be used alone or in combination of two or more. Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, oxime ester compounds, and the like. Examples of the photosensitizer include amines and quinones. In addition, the said adhesive agent should just be hardened | cured with an ultraviolet-ray or visible light, and should just form a radiation hardening adhesive layer, It is not limited to the above.

<Support>
The volume hologram laminate of the present embodiment may be provided on a support. The support may be employed for protecting and holding the volume hologram laminate.

  The support is not particularly limited as long as it has necessary strength and durability, and any support can be used. Moreover, although there is no restriction | limiting also in the shape of a support body, Usually, it forms in flat form or a film form. Moreover, there is no restriction | limiting in the material of a support body, Transparent or opaque may be sufficient.

  Examples of the transparent support material include inorganic materials such as glass, silicon, and quartz. Among these, glass is preferable. Examples of the opaque support material include a metal such as aluminum, a metal such as gold, silver, and aluminum coated with a dielectric such as magnesium fluoride and zirconium oxide on the transparent support. It is done.

  The surface of the support may be subjected to surface treatment. This surface treatment is usually applied to improve the adhesion between the support and the volume hologram laminate. Examples of the surface treatment include corona discharge treatment and formation of an undercoat layer on the support. Examples of the composition of the undercoat layer include halogenated phenols, partially hydrolyzed vinyl chloride-vinyl acetate copolymers, polyurethane resins, and the like.

Furthermore, the surface treatment may be performed for purposes other than the improvement of adhesiveness. Examples thereof include a reflective coating treatment for forming a reflective coating layer made of a metal such as gold, silver, and aluminum; a dielectric coating treatment for forming a dielectric layer such as magnesium fluoride and zirconium oxide, and the like. It is done. Further, these layers may be formed as a single layer or two or more layers.
These surface treatments may be provided for the purpose of controlling the gas and moisture permeability of the volume hologram laminate. Thereby, the reliability of the volume hologram can be further improved.

  The support may be provided only on either side of the volume hologram laminate, or may be provided on both sides. However, when the support is provided on both sides, at least one of the supports is configured to be transparent so as to transmit active energy rays (recording light, reference light, reproduction light, etc.). When bonding a support body and a volume hologram, highly transparent adhesives, such as a silicone adhesive and an acrylic adhesive, can be used.

<< Applications of volume hologram laminate >>
The volume hologram laminate of the present embodiment is suitably used for credit cards, banknotes, packaging, and the like for security purposes such as covers for books and magazines, gifts, and forgery prevention.

  Hereinafter, although the specific Example of this invention is described with a comparative example, this invention is not limited to these.

<< Preparation of Volume Hologram Laminate 101 >>
(1. Preparation of photosensitive layer)
In the dark room, the following components were put into a container and stirred at room temperature for 30 minutes. The obtained solution was filtered with a mesh to obtain a photosensitive composition for forming a volume hologram recording layer.
Matrix resin: Polyvinyl acetate (PVAc) 5.0 parts by mass Radical polymerizable monomer: 2-phenoxyethyl acrylate
6.0 parts by mass Radical polymerizable monomer: Bisphenol A epoxy diacrylate
1.0 part by mass radical polymerizable monomer: N-vinylcarbazole 3.0 part by mass radical photopolymerization initiator: tetrabutylammonium triphenylbutyl borate (organoborate polymerization initiator, Showa Denko)
0.01 parts by mass Sensitizer: Orange G (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.1 parts by mass Solvent: 25.0 parts by mass of ethyl acetate

  The above photosensitive composition is applied on a polyethylene terephthalate (PET) film (thickness 50 μm) as a substrate using a blade coater, dried in an environment of 20 ° C. and 50% RH for 30 minutes, and layer thickness A photosensitive layer of 15 μm was formed.

(2. Production of volume hologram recording layer)
Next, a volume hologram master is laminated on the photosensitive layer, and an argon ion laser (recording light wavelength: 458 nm, irradiation energy amount: 80 J / cm ² ) is incident from the substrate side to record the volume hologram on the photosensitive layer. A volume hologram recording layer was obtained. Here, an argon ion laser was incident on the photosensitive layer from the substrate side so that the angle at which the reproduction illumination light was diffracted and reflected to the normal of the surface of the volume hologram recording layer was 40 °.
Next, the volume hologram master was peeled from the volume hologram recording layer.

  Next, the produced volume hologram recording layer was placed at a position of 15 cm from a high-pressure mercury lamp (illuminance: 100 W), exposed on the entire surface for 60 minutes, and then heat-treated at 100 ° C. for 3 hours.

(3. Preparation of optical rotatory film)
On a biaxially stretched polyester film as an alignment film, nematic liquid crystal (manufactured by BASF: trade name “Pariocolor LC242”) was applied to a film thickness of 5 μm using a blade coater to obtain a nematic liquid crystal layer. Next, ultraviolet rays were irradiated at 100 mJ / cm ² to fix the helical pitch in a semi-cured state. When the biaxially stretched polyester film is viewed from the front, the color of the liquid crystal layer obtained at this time shows a color in which the reflection wavelength shifts from yellow at 590 nm to green at 530 nm when tilted vertically and horizontally. It was.

  A polyvinyl acetate (PVAc) layer dissolved in MEK (methyl ethyl ketone) / toluene was applied and formed on the liquid crystal layer in which the helical pitch was fixed in a semi-cured state with an ink jet using a layer thickness of 1 μm.

  Next, on the entire surface of the liquid crystal layer including the polyvinyl acetate layer, a chiral agent (BASF Corp.) is used so that the optical rotation angle α at 458 nm of the produced optical rotator film is about −10 ° using the inkjet method. Manufactured and trade name “Pariocolor LC756”) with a thickness of 1 μm.

Next, ultraviolet rays were irradiated at 800 mJ / cm ² to fix the film in a completely cured state, thereby forming a cholesteric liquid crystal layer. At this time, an optical rotatory film having a selective reflection wavelength λ ₀ of the cholesteric liquid crystal layer corresponding to about 340 nm was produced.

  The optical rotation angle of linearly polarized light emitted when linearly polarized light having a wavelength of 458 nm is incident on the produced optical rotator film from a direction perpendicular to the transparent substrate surface is measured using a polarimeter P-2100 manufactured by JASCO Corporation. As a result, the optical rotation angle for light of 458 nm was -11.5 °, and the optical rotation angle for light of 532 nm was -5 °.

(4. Production of volume hologram laminate)
An acrylate adhesive was applied to the surface of the volume hologram recording layer produced on the substrate opposite to the substrate so as to cover the entire surface, and the cholesteric liquid crystal layer side of the optical rotator film was bonded. On the other hand, the volume hologram laminated body 101 was produced by irradiating with a high pressure mercury lamp (illuminance of 100 W) for 3 minutes from a position of 15 cm.

<< Production of Volume Hologram Laminate 102 >>
In the production of the volume hologram laminate 101, 0.1 part by mass of safranin O (manufactured by Tokyo Chemical Industry Co., Ltd.) is added to the photosensitive composition, and laser light having a wavelength of 458 nm and a wavelength of 532 nm is applied at 80 mJ / cm when forming the volume hologram recording layer. ^The volume hologram laminate 102 was produced in the same manner except that the volume hologram recording layer having two diffraction reflection peak wavelengths was formed.

<< Preparation of Volume Hologram Laminate 103 >>
In the production of the volume hologram laminate 102, a chiral agent for producing an optical rotator film so that the optical rotation angle with respect to light having a wavelength of 458 nm is −24.5 ° and the optical rotation angle with respect to light having a wavelength of 532 nm is −9.8 °. A volume hologram laminate 103 was produced in the same manner except that the coating amount was adjusted.

<< Production of Volume Hologram Laminate 104 >>
In the production of the volume hologram laminate 102, a chiral agent for producing an optical rotator film so that the optical rotation angle with respect to light having a wavelength of 458 nm is −43.5 ° and the optical rotation angle with respect to light having a wavelength of 532 nm is −13.5 °. A volume hologram laminate 104 was produced in the same manner except that the coating amount was adjusted.

<< Production of Volume Hologram Laminate 105 >>
In the production of the volume hologram laminate 102, a chiral agent for producing an optical rotator film so that the optical rotation angle with respect to light having a wavelength of 458 nm is -65.1 ° and the optical rotation angle with respect to light having a wavelength of 532 nm is -18.9 °. A volume hologram laminate 105 was produced in the same manner except that the coating amount was adjusted.

<< Preparation of Volume Hologram Laminate 106 >>
In the production of the volume hologram laminate 102, a chiral agent for producing an optical rotator film so that the optical rotation angle with respect to light with a wavelength of 458 nm is -79.8 ° and the optical rotation angle with respect to light with a wavelength of 532 nm is -24.2 °. A volume hologram laminate 106 was produced in the same manner except that the coating amount was adjusted.

<< Preparation of Volume Hologram Laminate 107 >>
A volume hologram laminate 107 was produced in the same manner as in the production of the volume hologram laminate 101 except that a biaxially stretched polyester film was used instead of the optical rotator film.

<< Production of Volume Hologram Laminate 108 >>
In the production of the volume hologram laminate 101, a volume hologram laminate 108 was produced in the same manner except that a quarter wavelength plate was used instead of the optical rotator film.

<< Evaluation of volume hologram laminate >>
The following evaluation was performed about the produced volume hologram laminated body. The evaluation results are shown in Table I.

(Evaluation of the appearance of the image)
A volume hologram recording layer is placed on a flat plate having a luminance of 1000 lux on a flat plate in a room where a natural fluorescent lamp (FLR40S · N-SDN / M; manufactured by Panasonic) is installed. Arranged. And by 20 people extracted at random, the volume hologram laminate and the volume hologram recording layer (the optical rotator film, the biaxially stretched polyester film or the quarter wavelength plate) constituting the volume hologram laminate are not provided. ) Was visually compared and evaluated according to the following criteria.

◎: All 20 responded that the volume hologram laminate appeared to be equivalent to the volume hologram recording layer. ○: 18 to 19 out of 20 responded that the volume hologram laminate appeared to be equivalent to the volume hologram recording layer. Δ: 1 to 17 out of 20 people answered that the volume hologram laminate looks equivalent to the volume hologram recording layer ×: out of 20 people that the volume hologram laminate looks equivalent to the volume hologram recording layer No one responded

(Evaluation of anti-counterfeiting)
In the same manner as the formation of the photosensitive layer in the production of the volume hologram laminate 101, a photosensitive composition was applied on a substrate (PET film) to produce a photosensitive layer having a layer thickness after drying of 15 μm. The photosensitive layer was laminated on volume hologram laminates 101 to 108 sandwiched between glass substrates as original plates. Here, the prepared photosensitive layers are the volume hologram laminates 101 to 106 on the optical rotator film side, the volume hologram laminate 107 on the biaxially stretched polyester film side, and the volume hologram laminate 108 on the quarter wavelength plate side, respectively. Laminated to be placed.

Next, 458 nm and 532 nm laser beams are incident on the volume hologram laminate from the photosensitive layer side at an angle of diffracting and reflecting at 80 mJ / cm ² , and a volume hologram is recorded on the photosensitive layer to produce an evaluation volume hologram recording layer. did. However, for the volume hologram laminate 108, the laser beam was incident so that the vibration surface of the laser beam was parallel to the optical axis (slow axis or fast axis) of the quarter-wave plate. Next, the original plate (volume hologram laminates 101 to 108 sandwiched between glass substrates) was peeled from the produced volume hologram recording layer for evaluation. Next, a volume hologram recording layer for evaluation was placed at a position of 15 cm from a high-pressure mercury lamp (illuminance: 100 W), exposed for 60 minutes, and further subjected to heat treatment at 100 ° C. for 3 hours to obtain an evaluation sample.

  The produced sample for evaluation was placed on a flat plate having an illuminance of 1000 lux in a room where a natural fluorescent lamp (FLR40S · N-SDN / M; manufactured by Panasonic) was installed. Then, the reproduction sample was irradiated with reproduction light, and the extracted images were observed by the 20 extracted persons, and evaluated according to the following criteria.

◎: All 20 respondents said that the evaluation sample was blurred or the color looked out of comparison with the original volume hologram laminate ○: 18-19 out of 20 were for evaluation The sample replied that the reproduced image was blurred or the color look out of alignment with the volume hologram laminate of the original plate. Δ: 1 to 17 out of 20 samples were the volume hologram laminate of the original plate. In comparison, the replayed image is blurred or the color appears to be misaligned. ×: Out of 20 samples, the reconstructed image is blurred or the color is misaligned compared to the original volume hologram laminate. No one responded that they could see (all 20 responded that they looked the same image)

  As shown in Table I, it can be said that the volume hologram laminates 101 to 106 have a good image appearance and excellent anti-counterfeiting properties. Therefore, it can be said that the volume hologram laminate of the present invention is a volume hologram laminate in which the replication of the volume hologram is difficult and the appearance of the image is good as compared with the volume hologram laminate of the comparative example.

DESCRIPTION OF SYMBOLS 1 Volume hologram recording layer 2 Optical rotator film 10 Volume hologram laminated body

Claims (5)

A volume hologram recording layer;
An optical rotator film laminated on the volume hologram recording layer,
The volume hologram laminate, wherein an optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 ° at at least one of diffraction reflection peak wavelengths of the volume hologram recording layer.   The volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film satisfies 10 ° ≦ | α | ≦ 80 ° at any diffraction reflection peak wavelength. Item 2. The volume hologram laminate according to Item 1.   3. The volume according to claim 1, wherein the volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film is different for each diffraction reflection peak wavelength. Hologram laminate.   The optical rotation angle α of the optical rotator film satisfies 25 ° ≦ | α | ≦ 65 ° in at least one of diffraction reflection peak wavelengths of the volume hologram recording layer. The volume hologram laminate according to any one of the above.   The volume hologram recording layer has a plurality of diffraction reflection peak wavelengths, and the optical rotation angle α of the optical rotator film satisfies 25 ° ≦ | α | ≦ 65 ° at any diffraction reflection peak wavelength. The volume hologram laminate according to any one of claims 1 to 4.

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