JP2002060429A - Composition for recording three-dimensional hologram and three dimensional hologram-recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for three-dimensional hologram which is unnecessary for the dissolution in a solvent and the drying process on time of making a recording layer, and to obtain a three dimensional hologram- recording medium using the same. SOLUTION: The composition for recording a three-dimensional hologram for recording the interference fringes caused by the interference of a coherence light by depending on the difference between refractive indices, contains (a) an acrylic polyfunctional monomer having a specific structure, (b) a polymerization initiator to initiate the polymerization of the polyfunctional monomer (a) above described, and (c) a sensitizer to activate the polymerization initiator (b) above described; the three dimensional hologram-recording medium uses this composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a volume hologram recording medium for recording interference fringes with a difference in refractive index inside a recording layer, and a composition for recording a volume hologram used in the recording layer.

[0002]

2. Description of the Related Art A hologram records a pattern formed by two interference fringes on a photosensitive material, and irradiates the same laser beam from the same direction as a reference beam to a hologram. Is reproduced. This hologram technology is expected in the field of large-capacity memories for three-dimensional image display devices, images, and bit information.

[0003] Holograms are classified into several types according to the recording form of interference fringes. In recent years, so-called volume holograms, which record interference fringes with a difference in refractive index inside a recording layer, are being applied to uses such as three-dimensional displays and optical elements due to their high diffraction efficiency and excellent wavelength selectivity. Conventionally, silver halide or gelatin dichromate has been used as a photosensitive material for recording such a volume hologram. However, since these require wet development or complicated development and fixing, industrial production of holograms is difficult. However, it is not suitable for production in a typical manner, and has a problem that an image disappears due to moisture absorption even after recording.

In order to overcome the above-mentioned problems in the prior art, it has been disclosed in US Pat.
No. 526 and U.S. Pat. No. 3,993,485. The hologram formation mechanism by photopolymer is also described in “Applied Optics (APPL).
IED OPTICS)] [B. L. Booth (BL
Booth), Vol. 3, 593-601
Page (1975) and W.C. J. Tomlinson (WJT
omlinson), E.C. A. Chandros (EA)
Chordross), Vol. 15, No. 2, 53rd
4-541 (1976)]. However, these techniques initially fell short of the above-mentioned prior art in terms of refractive index modulation, which is a particularly important performance.

As an improvement technique, for example, US Pat. No. 4,942,102 and US Pat. No. 4,942,112
However, since these use a non-reactive plasticizer or the like to improve the refractive index modulation ability, they have a problem in the film strength of the formed hologram. The rate modulation was not enough. Therefore, Japanese Patent Application Laid-Open No. 5-107999 discloses a photopolymer composition as a photosensitive material for forming a recording layer,
(A) a cationic polymerizable compound, (b) a radical polymerizable compound, (c) a photo-radical polymerization initiator system for polymerizing (b), and (d) a cationic polymerization initiator system for polymerizing (a). A composition comprising each component, wherein the average refractive index of (a) is lower than the average refractive index of (b) is proposed, and according to the use of this composition, diffraction effect, wavelength selectivity, It is stated that a hologram having excellent refractive index modulation and film strength can be obtained.

[0006] However, the photopolymer composition usually requires a step of dissolving in a solvent and drying when forming a volume hologram recording layer. For this reason, it has been difficult to create an injection type recording layer in which, for example, a transparent substrate is bonded via a spacer.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition for a volume hologram which does not require a step of dissolving in a solvent and a step of drying when forming a recording layer. Another object of the present invention is to provide a volume hologram recording medium using the composition.

[0008]

The gist of the present invention is to provide a composition for recording a volume hologram, which records interference fringes caused by interference of coherent light by means of a difference in refractive index.
A polyfunctional monomer represented by the general formula (I), (b) a polymerization initiator for initiating the polymerization of the polyfunctional monomer of (a), and (c) a polymerization initiator for activating the polymerization initiator of (b). A volume hologram recording composition comprising a sensitizer.

[0009] Another aspect of the present invention resides in a volume hologram recording medium containing the composition. Also,
Another gist of the present invention resides in a method for producing a volume hologram recording medium, wherein substantially no solvent is used when forming a recording layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The volume hologram recording composition of the present invention comprises at least (a) a polyfunctional monomer represented by the general formula (I) (hereinafter sometimes referred to as component (a)); A polymerization initiator that initiates the polymerization of the functional monomer (hereinafter sometimes referred to as component (b)); and (c) a sensitizer that activates the polymerization initiator (b) (hereinafter component (c)) ).

[0011]

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(In the general formula (I), Y is a direct bond or
Represents a hexavalent linking group. R ₁ represents a hydrogen atom or an alkyl group, and the alkyl group may be substituted with a halogen atom, an alkoxy group, an alkylthio group, or a cyano group. R ₂ represents a divalent hydrocarbon group, and the hydrocarbon group may be substituted with a halogen atom, an alkoxy group, an alkylthio group, or a cyano group. Further, m and n each independently represent an integer of 1 to 3. ) In the general formula (I), R ₁ represents a hydrogen atom or an alkyl group, the alkyl group, a halogen atom, an alkoxy group, an alkylthio group, or may be substituted with a cyano group, but as R ₁ is , A hydrogen atom, a methyl group and an ethyl group are preferable, and a hydrogen atom and a methyl group are more preferable.

R ₂ represents a divalent hydrocarbon group;
The hydrocarbon group may be substituted with a halogen atom, an alkoxy group, an alkylthio group, or a cyano group.
_{As 2} , methylene group, ethylene group, propylene group,
Phenylene groups are preferred, and ethylene groups are more preferred.
In the general formula (I), Y represents a direct bond or a divalent to hexavalent bonding group, and the bonding group includes a benzene ring, a naphthalene ring,
A biphenyl ring or a ring in which these rings are bonded via a divalent bonding group is exemplified. These bonding groups may be substituted with a halogen atom, an alkoxy group, an alkylthio group, or an alkyl group, and the bonding site with the sulfur atom is not limited to these ring portions, but may be substituted with an alkyl group, an alkoxy group, or an alkylthio group. If it is, it may be the alkyl carbon of the substituent.

Preferred examples of the bonding group Y are those represented by the following formula (II) or (III).

[0015]

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[0016]

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(In the formula (II), R ₃ and R ₄ each represent a divalent hydrocarbon group, X represents a halogen atom, and m and n each independently represent an integer of 1-3. M and n in the formula (I), respectively, and t represents an integer of 0 to 4, provided that m + n + t ≦ 6. (In the formula (III), Q represents a sulfur atom, -CO-, -SO2
-Represents a direct bond, and X represents a halogen atom. m
And n each independently represent an integer of 1 to 3, and coincide with m and n in the general formula (I), respectively. Also, p
And q independently represent an integer of 1 to 4. However, m + p ≦
5 and n + q ≦ 5. In the formula (II), R 3 and R 4 represent a divalent hydrocarbon group, preferably having 1 to 12 carbon atoms, more preferably a methylene group, an ethylene group, a propylene group or a phenylene group, most preferably a methylene group. preferable.

X represents a halogen atom, preferably a chlorine atom or a bromine atom, more preferably a bromine atom. Where t
= 0, that is, those in which the bonding group of formula (II) is not substituted with a halogen atom are most preferred. In formula (III), Q is a sulfur _{atom, -CO -, - SO 2 -} , or represents a direct bond, -SO ₂ - are preferred.

X represents a halogen atom, preferably a chlorine atom or a bromine atom, more preferably a bromine atom. Where p
= Q = 0, that is, those in which the bonding group of the formula (III) is not substituted with a halogen atom are most preferred. Preferred specific examples of the monomer of the component (a) include, for example,
p-bis (β-methacryloyloxyethylthio) xylylene, p-bis (acryloyloxyethylthio) xylylene, m-bis (β-methacryloyloxyethylthio) xylylene, m-bis (acryloyloxyethyl) xylylene, p-bis (Β-methacryloyloxyethylthio) tetrabromoxylylene, 4,4′-bis (β-methacryloyloxyethylthio) diphenylsulfone, 4,4′-bis (acryloyloxyethylthio) diphenylsulfone, 4,4′- Bis (β-methacryloyloxyethylthio) diphenyl ketone, 4,
4′-bis (acryloyloxyethylthio) diphenyl ketone, 2,4-bis (β-methacryloyloxyethylthio) diphenyl ketone, 2,4-bis (acryloyloxyethylthio) diphenyl ketone, 4,4′-
Bis (β-methacryloyloxyethylthio) -3,
3 ′, 5,5′-tetrabromodiphenyl ketone, 4,
4'-bis (acryloyloxyethylthio) -3,
3 ', 5,5'-tetrabromodiphenyl ketone and the like.

Although these polyfunctional monomers have been disclosed by the present applicant (JP-A-61-72748 and JP-A-62-195357), this publication relates to the invention of lens materials. And there is no description about use in a volume hologram recording medium as in the present invention. Component (b) is a polymerization initiator that initiates the polymerization of the polyfunctional monomer of component (a), and is particularly preferably a photoradical polymerization initiator. Photo radical polymerization initiator, by the light for the first exposure for hologram creation,
Generates active radicals.

As the component (b), any known radical photopolymerization initiator can be used.
Azo compounds, azide compounds, organic peroxides, onium salts, bisimidazole derivatives, titanocene compounds,
Iodonium salts and the like are used. Of these, titanocene compounds are preferred. The photoradical polymerization initiator of the present invention is generally used in combination with a sensitizer (component (c)) which is a component that absorbs light.

As the sensitizer of component (c), a colored compound such as a dye is often used to absorb visible laser light, but when the final hologram is required to be colorless and transparent (for example, As a sensitizer for use as a head-up sprayer for automobiles and the like)
It is preferable to use a cyanine dye as described in JP-A-9803, JP-A-1-287105 and JP-A-3-5569.

When a titanocene compound is used as a photoradical generator, it is preferable to use a pyromethene compound as a sensitizer. The recording layer in the volume hologram recording medium of the present invention contains the above components (a) to (c)
In addition, if necessary, additives such as a chain transfer agent, a plasticizer, and a coloring agent may be added.

Further, a binder resin may be added as a binder in order to provide a uniform film thickness and to stably exist an interference film formed by polymerization by light irradiation. The binder resin may be any resin having good compatibility with the radical polymerizable composition, and specific examples thereof include chlorinated polyethylene, polymethyl methacrylate, copolymers of methyl methacrylate and other alkyl (meth) acrylates, and chlorides. Examples thereof include a copolymer of vinyl and acrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, ethyl cellulose, acetyl cellulose and the like.

In order to prepare a volume hologram recording medium using the composition for recording volume hologram of the present invention, the components (a), (b) and (c) are mixed together with a binder resin if necessary, and Coating on a transparent support, or a solvent may be added to these mixtures and mixed,
This is coated on a transparent support to form a recording layer. Subsequently, a protective layer may be provided on the recording layer.

As the transparent support, a transparent glass plate, an acrylic plate, a polyethylene terephthalate film, a polyethylene film or the like is used. Incidentally, the composition for volume hologram recording of the present invention, as a polyfunctional monomer,
It is characterized by using the compound represented by the general formula (I), whereby a recording layer can be formed without using a solvent and without drying.

As a preferred embodiment of a method for producing a volume hologram recording medium using a composition having such characteristics, there is a method of injecting the composition of the present invention into a transparent support. As a method of injecting into the transparent support, specifically, a set of two transparent supports is arranged so that the transparent supports are provided on both sides of the completed recording layer, and two transparent supports are provided. A method of injecting the composition during the process, or a method of injecting the composition from the injection hole provided in the box-shaped transparent support, or opening one surface of the box-shaped transparent support in advance After the composition is injected or dropped, a transparent support is covered on one open surface and sealed.

In the case of such a method, the recording layer can be formed substantially without using a solvent. The volume hologram recording medium can be used for three-dimensional image display, large-capacity memory for images and bit information, diffractive optical elements, and the like.

[0029]

Next, the present invention will be described in detail with reference to examples. Parts here are by weight.

Embodiment 1

Table 1 Polyfunctional monomer (the following compound (IV)) 98 parts Photopolymerization initiator (the following titanocene compound) 0.3 part Sensitizer (the following 1: 1 mixture of pyromethene compound) 0.07 part Chain transfer agent (Ethyl benzoate) 0.5 part Chain transfer agent (2-mercaptobenzothiazole) 0.3 part

[0031]

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[0032]

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[0033]

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The above mixture was stirred at room temperature and sufficiently dispersed. 5 mm thick as spacers on both ends of the slide glass
A 0 μm polyethylene terephthalate film (transparent support) was adhered and further covered with a slide glass to form a sample cell. One end of the sample cell is brought into contact with the mixture, and the mixture is introduced into the cell by capillary action,
A recording layer was formed. The formed recording layer has a wavelength of 514.5 n.
The two-beam interference exposure was performed with an argon ion laser of m. H at a wavelength of 632.8 nm simultaneously with two-beam interference exposure
The hologram formation process was monitored with an eNe laser to evaluate the diffraction efficiency. It was confirmed that the diffraction efficiency was improved as the exposure intensity was increased (a conceptual diagram of two-beam interference exposure is shown in FIG. 1, and a graph showing the diffraction efficiency is shown in FIG. 2). Example 2

Table 2 Polyfunctional monomer (compound (V) below) 98 parts Photopolymerization initiator (same compound as in Example 1) 0.3 parts Sensitizer (same mixture as in Example 1) 0.07 parts Chain transfer agent (Ethyl benzoate) 0.5 part Chain transfer agent (2-mercaptobenzothiazole) 0.3 part

[0035]

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The above mixture was stirred at room temperature and sufficiently dispersed. 5 mm thick as spacers on both ends of the slide glass
A 0 μm polyethylene terephthalate film (transparent support) was adhered and further covered with a slide glass to form a sample cell. One end of the sample cell is brought into contact with the mixture, and the mixture is introduced into the cell by capillary action,
A recording layer was formed. The formed recording layer has a wavelength of 514.5 n.
The two-beam interference exposure was performed with an argon ion laser of m. H at a wavelength of 632.8 nm simultaneously with two-beam interference exposure
The hologram formation process was monitored with an eNe laser, and the diffraction efficiency was evaluated in the same manner as in Example 1. It was confirmed that the diffraction efficiency was improved as the exposure intensity was increased.

[0037]

According to the present invention, it is possible to provide a composition for a volume hologram which does not require a step of dissolving in a solvent and drying the recording layer, and a volume hologram recording medium using the same.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of two-beam interference exposure on a volume hologram recording medium.

FIG. 2 is a graph showing the diffraction efficiency of the volume hologram recording medium in Example 1.

Claims (8)

[Claims] 1. A volume hologram recording composition for recording interference fringes generated by interference of coherent light by a difference in refractive index, wherein (a) a polyfunctional monomer represented by the general formula (I): (B) A polymerization initiator for initiating polymerization of the polyfunctional monomer of (a), and (c) a sensitizer for activating the polymerization initiator of (b), for volume hologram recording. Composition. Embedded image (In the general formula (I), Y represents a direct bond or a divalent to hexavalent bonding group. R 1 represents a hydrogen atom or an alkyl group, and the alkyl group is a halogen atom, an alkoxy group, an alkylthio group, or a cyano group. R2 may be substituted with
Represents a divalent hydrocarbon group, and the hydrocarbon group may be substituted with a halogen atom, an alkoxy group, an alkylthio group, or a cyano group. M and n are each independently 1
Represents an integer of 1 to 3. ) 2. The volume hologram recording composition according to claim 1, wherein the polymerization initiator is a photo-radical polymerization initiator. 3. The volume hologram recording composition according to claim 2, wherein the polymerization initiator is a titanocene compound. 4. The composition for recording a volume hologram according to claim 1, wherein the sensitizer is a dye that absorbs light in a visible region. 5. The composition for recording a volume hologram according to claim 4, wherein the sensitizer is a pyromethene dye. 6. A volume hologram recording medium, wherein the recording layer contains the composition according to claim 1. Description: 7. The volume hologram recording medium according to claim 6, wherein transparent media are provided on both sides of the recording layer. 8. The method for manufacturing a volume hologram recording medium according to claim 6, wherein a solvent is not substantially used in the step of forming a recording layer.