JP4751751B2 - Holographic recording composition, method for producing the same, and optical recording medium - Google Patents

Description

  The present invention is capable of recording and reproducing information using a laser beam, and in particular, a holographic recording composition suitable for producing a volume holographic optical recording medium having a thick recording layer, and the holographic recording composition The present invention relates to an optical recording medium using the composition.

  Conventionally, development of a holographic optical recording medium using a holographic principle has been advanced. When recording information, these holographic optical recording media superimpose information light including image information and reference light in a recording layer made of a photosensitive composition, and write interference fringes formed at that time in the recording layer. Is done by. On the other hand, when information is reproduced, reference light is incident on the recording layer on which information is recorded at a predetermined angle, whereby light diffraction of the reference light due to the formed interference fringes occurs and information light is reproduced.

  In recent years, volume holography, in particular digital volume holography, has been developed in the practical field and has attracted attention in order to realize ultra-high density optical recording. Volume holography is a method of writing interference fringes in three dimensions by actively utilizing the thickness direction of the optical recording medium. Increasing the thickness increases the diffraction efficiency and increases the recording capacity by using multiple recording. There is a feature that can be achieved. Digital volume holography is a computer-oriented holographic recording method that uses a recording medium and a recording method similar to those of volume holography, but restricts image information to be recorded to a binarized digital pattern. In this digital volume holography, for example, image information such as an analog picture is once digitized, developed into two-dimensional digital pattern information, and recorded as image information. At the time of reproduction, the digital pattern information is read and decoded so that the original image information is restored and displayed. As a result, even if the S / N ratio (signal-to-noise ratio) is somewhat poor during reproduction, the original information can be reproduced with high fidelity by performing differential detection or performing error correction by encoding binary data. Can be reproduced (see Patent Document 1).

  The volume holographic optical recording medium is required to record and reproduce high-resolution surface information that fully exhibits the multi-recording property, which is a feature of the volume holographic optical recording medium. From these viewpoints, a holographic recording composition having a urethane bond in a matrix (see Patent Document 2) and a holographic recording composition having a ring-opening polymerizable compound such as oxirane (see Patent Document 3) are proposed. Has been. However, in the holographic recording composition proposed by the above prior art, since the raw material of the matrix is unstable with respect to moisture, humidity management is necessary when producing a holographic optical recording medium, At present, development of a composition for holographic recording capable of producing a holographic optical recording medium more easily and with stable quality is desired.

  On the other hand, it is known that an oxazoline compound can be easily formed into a polymer by mixing with a ring-opening polymerization initiator and heating (see Non-Patent Document 1). However, it has not been known to use them in holographic optical recording compositions.

Japanese Patent Laid-Open No. 11-311936 JP-T-2005-502918 Japanese Patent No. 2873126 Macromolecules, 1987, 20, 2

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides a holographic recording composition that is excellent in water stability and can efficiently produce a holographic optical recording medium, a method for producing the same, and optical recording using the holographic recording composition. The purpose is to provide a medium.

  In order to solve the above-mentioned problems, as a result of intensive studies by the present inventor, for holographic recording comprising a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring, a radical polymerizable monomer, and a photopolymerization initiator It has been found that the composition is excellent in water stability, can efficiently produce a holographic optical recording medium, and can effectively solve conventional problems.

This invention is based on the said knowledge by this inventor, and the means for solving the said subject are as follows. That is,
<1> A holographic recording composition comprising a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring, a radical polymerizable monomer, and a photopolymerization initiator.
<2> The holographic recording composition according to <1>, wherein the polymer obtained by ring-opening polymerization of a compound having an oxazoline ring has a repeating unit represented by the following general formula (1).
However, in said general formula (1), R represents either an alkyl group or an aryl group. The alkyl group and aryl group may each have a substituent. n represents an integer of 1 or more.
<3> The holographic recording composition according to any one of <2> to <2>, wherein the compound having an oxazoline ring is represented by the following general formula (2).
However, in said general formula (2), R represents either an alkyl group or an aryl group.
The alkyl group and aryl group may each have a substituent.
<4> The holographic method according to any one of <1> to <3>, wherein a glass transition temperature (Tg) of a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring is −20 ° C. or higher and 30 ° C. or lower. It is a composition for recording.
<5> A method for producing the holographic recording composition according to any one of <1> to <4>, comprising a step of ring-opening polymerization of a compound having an oxazoline ring by heat. A method for producing a holographic recording composition.
<6> An optical recording medium comprising a holographic recording layer comprising the holographic recording composition according to any one of <1> to <4>.
<7> The optical recording medium according to <6>, including a first substrate, a filter layer, a holographic recording layer, and a second substrate.
<8> The optical recording medium according to <7>, wherein the second substrate has a servo pit pattern.
<9> The optical recording medium according to <8>, wherein the servo pit pattern surface has a reflective film.
<10> The optical recording medium according to any one of <7> to <9>, wherein the filter layer transmits the first light and reflects the second light.
<11> The optical recording medium according to any one of <7> to <10>, further including a first gap layer for smoothing a first substrate surface between the filter layer and the reflective film.
<12> The optical recording medium according to any one of <7> to <11>, wherein a second gap layer is provided between the holographic recording layer and the filter layer.
<13> The optical recording medium according to any one of <6> to <12> is irradiated with coherent information light and reference light, and an interference image is formed by the information light and the reference light. , And recording the interference image on a holographic recording layer of the optical recording medium.
<14> An optical recording medium is irradiated with the information light and the reference light so that the optical axis of the information light and the optical axis of the reference light are coaxial, and is generated by interference between the information light and the reference light. The optical recording method according to <13>, wherein the interference image is recorded on the holographic recording layer of the optical recording medium.
<15> Optical reproduction, wherein information is reproduced by irradiating reference light onto an interference pattern recorded on a holographic recording layer by the optical recording method according to any one of <13> to <14> Is the method.
<16> The optical recording medium according to any one of <6> to <12> is irradiated with coherent information light and reference light, and an interference image is formed by the information light and the reference light. The optical recording / reproducing apparatus records the interference image on the optical recording medium.

  According to the present invention, a conventional holographic recording composition capable of solving various conventional problems, excellent in water stability, and capable of efficiently producing a holographic optical recording medium, a method for producing the same, and the holographic recording An optical recording medium using the composition can be provided.

(Holographic recording composition)
The holographic recording composition of the present invention comprises at least a polymer (binder) obtained by ring-opening polymerization of a compound having an oxazoline ring, a radical polymerizable monomer, and a photopolymerization initiator, and further required. Accordingly, it contains other components.

<Binder>
The binder is also called a matrix, and is a polymer for holding a radically polymerizable monomer and a photopolymerization initiator related to recording and storage, and for the purpose of enhancing the effect of improving coating properties, film strength, and hologram recording characteristics. It is what is used.
The binder is a polymer formed by ring-opening polymerization of a compound having an oxazoline ring, and is formed by reacting the compound having the oxazoline ring and further other components as necessary.
The binder has a linear or three-dimensional cross-linking structure, and is appropriately selected in consideration of compatibility with a radical polymerizable monomer.

The binder is not particularly limited as long as the compound having an oxazoline ring, which will be described later, is a polymer obtained by ring-opening polymerization, and can be appropriately selected according to the purpose. Among these, the following general formula ( Those having a repeating unit represented by 1) are particularly preferred.
However, in said general formula (1), R represents either an alkyl group or an aryl group. The alkyl group and aryl group may each have a substituent. n represents an integer of 1 or more.

In the structural formula (1), the alkyl group represented by R is not particularly limited and may be appropriately selected depending on the intended purpose, but preferably has 1 to 20 carbon atoms. Is more preferable, and 1 to 5 is particularly preferable.
Specific examples of the alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, and a heptyl group. Octyl group, tertiary octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, and the like. These may further have a substituent. Examples of the substituent include a phenyl group, an amino group, an ether group, a halogen atom, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, An acylamino group, a carbamoyl group, a cyano group, a heterocyclic group and the like can be mentioned. Among these, an ether group and an acyloxy group are more preferable.

In the structural formula (1), the aryl group represented by R is not particularly limited and may be appropriately selected depending on the intended purpose, but preferably has 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms. Is more preferable, and 6 is particularly preferable.
Specific examples of the aryl group include a phenyl group, a tolyl group, a naphthyl group, and an anthranyl group. These may further have a substituent. Examples of the substituent include an alkyl group, a phenyl group, an amino group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, A carbamoyl group, a cyano group, a heterocyclic group and the like can be mentioned, and among these, an alkyl group is particularly preferable.

  In the structural formula (1), the integer of 1 or more represented by n is preferably 1 to 1,000, more preferably 1 to 100, and particularly preferably 10 to 30.

  The glass transition temperature (Tg) of the binder is not particularly limited, but the glass transition temperature range is −50 ° C. to 50 ° C. considering that recording is possible with low energy and recording data is retained. ° C or lower is preferable, -30 ° C or higher and 40 ° C or lower is more preferable, and -20 ° C or higher and 30 ° C or lower is particularly preferable.

-Compound having oxazoline ring-
The compound having an oxazoline ring is not particularly limited as long as it has one or more oxazoline rings in one molecule, and can be appropriately selected according to the purpose. It is preferable to have 1-5, and more preferably 1-2.

The structure of the compound having an oxazoline ring is not particularly limited, but the 4-position and 5-position substituents of the oxazoline ring are each preferably an alkyl group or a hydrogen atom.
There is no restriction | limiting in particular as said alkyl group, Although it can select suitably according to the objective, It is preferable that C1-C10 is preferable, 1-5 are more preferable, and 1-2 are especially preferable.
Specific examples of the alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, and a heptyl group. Octyl group, tertiary octyl group, 2-ethylhexyl group, decyl group, and the like. These may further have a substituent. Examples of the substituent include a phenyl group, an amino group, an ether group, a halogen atom, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, An acylamino group, a carbamoyl group, a cyano group, a heterocyclic group and the like can be mentioned. Among these, an ether group and an acyloxy group are more preferable.
Among these, considering the ease of ring-opening polymerization, the 4- and 5-position substituents of the oxazoline ring are particularly preferably hydrogen atoms.

In the compound having an oxazoline ring, the substituent at the 2-position of the oxazoline ring is preferably an alkyl group or an aryl group in view of the ease of ring-opening polymerization.
There is no restriction | limiting in particular as said alkyl group, Although it can select suitably according to the objective, It is preferable that it is C1-C20, 1-10 are more preferable, and 1-5 are especially preferable.
Specific examples of the alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, and a heptyl group. Octyl group, tertiary octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, and the like. These may further have a substituent. Examples of the substituent include a phenyl group, an amino group, an ether group, a halogen atom, an alkoxy group, an aryloxy group, an acyl group, an alkoxycarbonyl group, an acyloxy group, An acylamino group, a carbamoyl group, a cyano group, a heterocyclic group and the like can be mentioned. Among these, an ether group and an acyloxy group are more preferable.
There is no restriction | limiting in particular as said aryl group, Although it can select suitably according to the objective, It is preferable that carbon number is 6-20, 6-10 are more preferable, and 6 is especially preferable.
Specific examples of the aryl group include a phenyl group, a tolyl group, a naphthyl group, and an anthranyl group. These may further have a substituent. Examples of the substituent include an alkyl group, a phenyl group, an amino group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, A carbamoyl group, a cyano group, a heterocyclic group, etc. are mentioned, Among these, an alkyl group is more preferable.

As the compound having such an oxazoline ring, specifically, a compound represented by the following general formula (2) is particularly preferable.
However, in said general formula (2), R represents either an alkyl group or an aryl group. The alkyl group and aryl group may each have a substituent. In addition, when several oxazoline rings substitute as this substituent through a coupling group, a polyfunctional body is represented.

Specific examples of the structure of the compound having an oxazoline ring are shown below, but are not limited thereto. These compounds having an oxazoline ring may be used alone or in combination of two or more.

  The compound having an oxazoline ring can be purchased as a reagent for a part of the compounds, and can be easily synthesized by the method described in Macromolecules, 1987, 20, 2 or the like.

  As content in the said holographic recording composition of the compound which has the said oxazoline ring, 10-95 mass% is preferable with respect to the total mass of this holographic recording composition, and 35-90 mass% is more preferable. When the content is less than 10% by mass, a holographic recording layer made of the holographic recording composition may not obtain a stable interference image, and when it exceeds 95% by mass, it is desirable in terms of diffraction efficiency. Performance may not be obtained.

-Other ingredients-
Examples of the other components include a ring-opening polymerization initiator. The ring-opening polymerization initiator is not particularly limited as long as the compound having an oxazoline ring can be subjected to ring-opening polymerization, and can be appropriately selected according to the purpose. Specific examples include an acid generator and an alkylating agent. Is mentioned. Examples of the acid generator include 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1 , 3,5-triazine, diphenyliodonium tetrafluoroborate, 4,4′-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate , Etc. Examples of the alkylating agent include methyl trifluoromethanesulfonate, ethyl trifluoromethanesulfonate, octyl trifluoromethanesulfonate, methyl p-toluenesulfonate, ethyl p-toluenesulfonate, and the like. These may be used individually by 1 type and may use 2 or more types together.
The content of the ring-opening polymerization initiator in the holographic recording composition is not particularly limited as long as a compound having an oxazoline ring can be subjected to ring-opening polymerization, and can be appropriately selected according to the purpose. 0.01-10 mass% is preferable with respect to the total mass of the compound to have, 0.01-5 mass% is more preferable, 0.1-1 mass% is still more preferable.

-Analytical method of compound having oxazoline ring-
The compound having an oxazoline ring is obtained by extracting a holographic recording layer portion of an optical recording medium having a holographic recording layer made of the holographic recording composition of the present invention with an organic solvent such as dioxane, and performing GPC or HPLC. And can be identified by NMR or the like.

-Analytical method of polymer obtained by ring-opening polymerization of compound having oxazoline ring-
The polymer obtained by ring-opening polymerization of the compound having an oxazoline ring is a polyamide, and its amide group can be confirmed by infrared absorption spectrum, and the amide bond that has been bonded by treating the polymer with an acid or a base. And the corresponding polyamines can be detected.

<Radically polymerizable monomer>
The radical polymerizable monomer means a compound that participates in information recording and can perform radical polymerization with a photopolymerization initiator described later.
The radical polymerizable monomer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a monomer having an unsaturated bond such as an acryloyl group, a methacryloyl group, a styryl group, an allyl group, or a vinyl group. Etc. are preferable. These radical polymerizable monomers may be monofunctional or polyfunctional.
Specific examples of the radical polymerizable monomer include acryloylmorpholine, phenoxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate. Neopentyl glycol PO-modified diacrylate, 1,9-nonanediol diacrylate, hydroxypivalate neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, penta Erythritol hexaacrylate, EO-modified glycerol triacrylate, trimethylol Lopantriacrylate, EO-modified trimethylolpropane triacrylate, 2-naphth-1-oxyethyl acrylate, 2-carbazoyl-9-ylethyl acrylate, (trimethylsilyloxy) dimethylsilylpropyl acrylate, vinyl-1-naphthoate, N-vinyl Examples thereof include carbazole, 2,4-dibromophenyl acrylate, 2,4,6-tribromophenyl acrylate, pentabromoacrylate, phenylthioethyl acrylate, tetrahydrofurfuryl acrylate, and the like. Among these, 2,4,6-tribromophenyl acrylate, EO-modified bisphenol A diacrylate, 2,4-dibromophenyl acrylate, and N-vinylcarbazole are particularly preferable. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as content in the said holographic recording composition of the said radically polymerizable monomer, Although it can select suitably according to the objective, It is 5 with respect to the total mass of the said holographic recording composition. -50 mass% is preferable and 5-20 mass% is more preferable. If the content is less than 5% by mass, a sufficient reproduced image may not be obtained when recording and reproducing. If the content exceeds 50% by mass, scattered light is mixed with the reproduced light, so that a correct reproduced image is obtained. It may not be obtained.

<Photopolymerization initiator>
The photopolymerization initiator is not particularly limited as long as it can be a starting species that causes a polymerization reaction by light, and can be appropriately selected according to the purpose. For example, a radical polymerizable initiator is preferably used. Can be mentioned.
The radical polymerization initiator is not particularly limited as long as it has sensitivity to recording light, and can be appropriately selected according to the purpose. Examples thereof include materials that cause radical polymerization by light irradiation.
Examples of the radical polymerization initiator include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1′-biimidazole, 2,4,6-tris. (Trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1,3,5-triazine, diphenyliodonium tetrafluoroborate, diphenyliodonium hexa Fluorophosphate, 4,4′-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one, benzophenone, Thioxanthone, 2,4,6-trimethylbenzoy Diphenyl acyl phosphine oxide, triphenyl butyl borate tetraethyl ammonium, bis (η-5-2,4- cyclopentadiene-1-yl) - bis [2,6-difluoro-3-(1H-pyrrol-1-yl) phenyl ], Titanium , diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, and the like. These may be used individually by 1 type and may use 2 or more types together. In addition, you may use together the sensitizing dye mentioned later according to the wavelength of the light to irradiate.

  There is no restriction | limiting in particular as content in the said holographic recording composition of the said photoinitiator, Although it can select suitably according to the objective, It is 0 with respect to the total mass of the said holographic recording composition. .01 to 5% by mass is preferable, and when it is within this range, the initiation reaction occurs efficiently, and the light reaches the bottom of the recording medium, so that the occurrence of errors in the recording data can be suppressed. Moreover, as this content, 1-3 mass% is more preferable.

<Other ingredients>
Examples of the other components include sensitizing dyes, polymerization inhibitors or antioxidants, and photothermal conversion materials. The other components that can be contained in the holographic recording composition of the present invention are not limited to these.

-Sensitizing dye-
The holographic recording composition can contain a sensitizing dye as required. There is no restriction | limiting in particular as this sensitizing dye, According to the objective, it can select suitably, "Research Disclosure, Vol.200, December, 1980, Item 20036" and "sensitizer" (p.160- p.163, Kodansha; Katsumi Tokumaru, Nobuo Okawara / ed., 1987) and the like can be used.
Specific examples of the sensitizing dye include a 3-ketocoumarin compound described in JP-A-58-15603, a thiopyrylium salt described in JP-A-58-40302, and JP-B-59-28328. The naphthothiazole merocyanine compound described in JP-A-60-53300, the merocyanine compound described in JP-B-61-9621, JP-A-62-2842, JP-A-59-89303, and JP-A-60-60104 Can be mentioned.
Further, the dyes described in “Functional dye chemistry” (1981, CMC Publishing Co., p.393 to p.416), “Coloring materials” (60 [4] 212-224 (1987)), and the like are also included. be able to. Specific examples include a cationic methine dye, a cationic carbonium dye, a cationic quinoneimine dye, a cationic indoline dye, and a cationic styryl dye.
In addition, coumarin (including ketocoumarin or sulfonocoumarin) dyes, melostyryl dyes, oxonol dyes, hemioxonol dyes and other keto dyes; non-ketopolymethine dyes, triarylmethane dyes, xanthene dyes, anthracene dyes, rhodamine dyes, acridine dyes Non-keto dyes such as aniline dyes and azo dyes; Non-ketopolymethine dyes such as azomethine dyes, cyanine dyes, carbocyanine dyes, dicarbocyanine dyes, tricarbocyanine dyes, hemicyanine dyes, styryl dyes; azine dyes, oxazine dyes, thiazines Dyestuffs, quinoline dyes, quinoneimine dyes such as thiazole dyes, and the like are also included in the spectral sensitizing dye.
The said sensitizing dye may be used individually by 1 type, and may be used in combination of 2 or more type.

  There is no restriction | limiting in particular as content in the said holographic recording composition of the said sensitizing dye, Although it can select suitably according to the objective, It is 0.00 with respect to the total mass of the said holographic recording composition. 001-5 mass% is preferable, and when it is within this range, the initiation reaction occurs efficiently and the light reaches the bottom of the recording medium, so that the occurrence of errors in the recording data can be suppressed. Moreover, as this content, 0.1-2 mass% is more preferable.

-Polymerization inhibitor or antioxidant-
The holographic recording composition may contain a polymerization inhibitor or an antioxidant for the purpose of improving the storage stability of the holographic recording composition.
The polymerization inhibitor or antioxidant is not particularly limited and may be appropriately selected depending on the intended purpose. Specific examples include hydroquinone, p-benzoquinone, hydroquinone monomethyl ether, and 2,6-ditertiary butyl. -P-cresol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), trifel phosphite, trisnonylphenyl phosphite, phenothiazine, N-isopropyl-N'-phenyl-p-phenylenediamine, etc. Is mentioned.

  There is no restriction | limiting in particular as content in the said holographic recording composition of the said polymerization inhibitor or antioxidant, Although it can select suitably according to the objective, 3 with respect to the whole quantity of the said radically polymerizable monomer. The mass% or less is preferable. When the addition amount exceeds 3% by mass, the polymerization may be slowed or may not be polymerized when it is remarkable.

-Photothermal conversion material-
The holographic recording composition may contain a photothermal conversion material for the purpose of improving the sensitivity of the holographic recording layer made of the holographic recording composition.
The photothermal conversion material is not particularly limited and can be appropriately selected according to the intended function and performance. For example, simplicity when added to a holographic recording layer together with a photopolymer, scattering of incident light, etc. Organic dyes are preferable in view of the property that they do not cause irradiance, and infrared absorbing dyes are preferable in that they do not absorb or scatter light from a light source used for recording.

  The infrared absorbing dye is not particularly limited and may be appropriately selected depending on the intended purpose. Cationic dyes, complex salt-forming dyes, quinone neutral dyes, and the like are preferable. Further, the maximum absorption wavelength of the infrared absorbing dye is preferably in the range of 600 to 1,000 nm, and more preferably in the range of 700 to 900 nm.

The content of the infrared absorbing dye in the holographic recording composition is determined by the absorbance of the wavelength having the highest absorbance in the infrared region in the produced recording material. As this light absorbency, the range of 0.1-2.5 is preferable, and the range of 0.2-2.0 is more preferable.
The content of the infrared absorbing dye in the holographic recording composition is preferably 0.001 to 5% by mass with respect to the total mass of the holographic recording composition. Can be generated. Moreover, as this content, 0.1-2 mass% is more preferable.

  The holographic recording composition may further contain a component that diffuses in a direction opposite to the polymerization component, or an acid-cleavage structure, if necessary, in order to alleviate the volume change during polymerization. In addition to the polymer, a compound having the above may be added separately.

(Method for producing holographic optical recording composition)
The method for producing a holographic optical recording composition of the present invention comprises a step of ring-opening polymerization of a compound having an oxazoline ring by heat, and further comprises other steps as necessary.
In the matrix forming step, each compound may be added at once or sequentially, but it is preferable to add them at a time for the convenience of the production method.
Subsequently, the composition for optical recording of this invention can be manufactured by mixing the obtained matrix, a radically polymerizable monomer, a photoinitiator, and also another component as needed.

The optical recording composition of the present invention can be used for various compositions capable of recording information by irradiation with light containing information, and is particularly preferably used for a volume holographic recording composition.
If the optical recording composition has a sufficiently low viscosity, a holographic recording layer can be formed by casting. On the other hand, when the viscosity is so high that casting cannot be performed, the optical recording composition is placed on a first substrate to be described later using a dispenser, and the optical recording composition is covered with the second substrate. And can be spread over the entire surface to form a record.

(Optical recording medium)
The recording medium of the present invention has a three-dimensional recording layer. The three-dimensional recording layer is a laminated recording layer using two-photon absorption, a holographic recording layer using light interference, or the like. Hereinafter, an optical recording medium for holographic recording will be specifically described.
The optical recording medium of the present invention has a holographic recording layer comprising the holographic recording composition of the present invention, preferably a first substrate, a filter layer, a holographic recording layer, and a second substrate. And, if necessary, other layers such as a reflective film, a first gap layer, a second gap layer, and the like.

  The optical recording medium is not particularly limited as long as it can be recorded and reproduced using the principle of hologram, and records a large amount of information such as a relatively thin planar hologram or a three-dimensional image for recording information such as two dimensions. It may be a volume hologram, and may be either a transmission type or a reflection type. The hologram recording method may be any, for example, an amplitude hologram, a phase hologram, a blazed hologram, a complex amplitude hologram, or the like. Among these, information recording in the volume holographic recording area is performed by irradiating the volume holographic recording area with information light and reference light as a coaxial light beam, and recording information by an interference pattern due to interference between the information light and the reference light. The so-called collinear method is particularly preferable.

-First substrate and second substrate-
The shape, structure, size and the like of the substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a disk shape and a card shape. It is necessary to select a material that can ensure the mechanical strength of the medium. In addition, when light used for recording and reproduction enters through the substrate, it is necessary to be sufficiently transparent in the wavelength region of the light used.
As the substrate material, glass, ceramics, resin, and the like are usually used, but resin is particularly preferable from the viewpoint of moldability and cost.
Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like. Among these, polycarbonate resin and acrylic resin are particularly preferable from the viewpoints of moldability, optical characteristics, and cost.
The substrate may be appropriately synthesized or a commercially available product may be used.

  In the second substrate, address-servo areas as a plurality of positioning areas extending linearly in the radial direction are provided at predetermined angular intervals, and a sector-shaped section between adjacent address-servo areas becomes a data area. ing. In the address-servo area, information for performing focus servo and tracking servo by the sampled servo method and address information are recorded in advance by an emboss pit (servo pit) pattern or the like (preformat). Note that the focus servo can be performed using the reflective surface of the reflective film. As information for performing the tracking servo, for example, a wobble pit can be used. If the optical recording medium has a card shape, the servo pit pattern may be omitted.

  There is no restriction | limiting in particular as thickness of the said board | substrate, According to the objective, it can select suitably, 0.1-5 mm is preferable and 0.3-2 mm is more preferable. If the thickness of the substrate is less than 0.1 mm, the distortion of the shape during storage of the disc may not be suppressed. If the thickness exceeds 5 mm, the mass of the entire disc increases and an excessive load is applied to the drive motor. Sometimes.

-Holographic recording layer-
The holographic recording layer can record information using holography, and is composed of the holographic recording composition of the present invention.

There is no restriction | limiting in particular as thickness of the said holographic recording layer, According to the objective, it can select suitably, 1-1000 micrometers is preferable and 100-700 micrometers is more preferable.
When the thickness of the holographic recording layer is in the above-mentioned preferable numerical range, a sufficient S / N ratio can be obtained even if shift multiplexing of 10 to 300 is performed, and the thickness is more preferable as described above. A numerical range is advantageous in that it is significant.

-Filter layer-
The filter layer is provided on a servo pit pattern of the second substrate, a reflective layer described later, or a first gap layer described later.
The filter layer has a wavelength selective reflection function that reflects only light of a specific wavelength from among a plurality of types of light, transmits the first light, and reflects the second light. In particular, even if the incident angle changes, the selective reflection wavelength does not shift, and when the reflection film is provided, irregular reflection from the reflection film of the optical recording medium by information light and reference light is prevented, and noise is generated. The optical recording with high resolution and excellent diffraction efficiency can be obtained by laminating the filter layer on the optical recording medium.
The filter layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dichroic mirror layer, a color material-containing layer, a dielectric vapor deposition layer, a single layer or two or more cholesteric layers and necessary It is formed by a laminate in which at least one of other layers appropriately selected according to the above is laminated.
The filter layer may be laminated together with the holographic recording layer directly on the substrate by coating or the like, and is laminated on a substrate such as a film to produce a filter layer, which is laminated on the substrate. Also good.

-Reflective film-
The reflective film is formed on the surface of the servo pit pattern of the substrate.
As the material of the reflective film, a material having a high reflectance with respect to recording light or reference light is preferably used. When the wavelength of light to be used is 400 to 780 nm, for example, Al, Al alloy, Ag, Ag alloy, etc. are preferably used. When the wavelength of light to be used is 650 nm or more, it is preferable to use Al, Al alloy, Ag, Ag alloy, Au, Cu alloy, TiN, or the like.
As the reflection film, an optical recording medium that reflects light and can be written or erased, such as a DVD (digital video disk), is used. It is also possible to additionally write and rewrite directory information, such as whether or not there is an error and how the alternation process was performed, without affecting the hologram.

The formation of the reflective film is not particularly limited and can be appropriately selected depending on the purpose. Various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating, etc. An electron beam evaporation method or the like is used. Among these, the sputtering method is excellent in terms of mass productivity and film quality.
The thickness of the reflective film is preferably 50 nm or more, and more preferably 100 nm or more so that sufficient reflectance can be achieved.

-First gap layer-
The first gap layer is provided between the filter layer and the reflective film as necessary, and is formed for the purpose of smoothing the surface of the first substrate. It is also effective for adjusting the size of the hologram generated in the holographic recording layer. That is, since the holographic recording layer needs to form an interference region for recording reference light and information light to a certain size, a gap may be provided between the holographic recording layer and the servo pit pattern. It becomes effective.
The first gap layer can be formed, for example, by applying a material such as an ultraviolet curable resin on the servo pit pattern by spin coating or the like and curing it. Moreover, when using what apply | coated and formed on the transparent base material as a filter layer, this transparent base material will work | function also as a 1st gap layer.
There is no restriction | limiting in particular as thickness of the said 1st gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

-Second gap layer-
The second gap layer is provided between the holographic recording layer and the filter layer as necessary.
The material of the second gap layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, triacetyl cellulose (TAC), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS) ), Transparent resin films such as polysulfone (PSF), polyvinyl alcohol (PVA), polymethyl methacrylate = polymethyl methacrylate (PMMA), etc., or JSR brand name ARTON film or Nippon Zeon brand name ZEONOR And norbornene-based resin films. Among these, those having high isotropic properties are preferred, and TAC, PC, trade name ARTON, and trade name ZEONOR are particularly preferred.
There is no restriction | limiting in particular as thickness of the said 2nd gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

Here, the optical recording medium of the present invention will be described in more detail with reference to the drawings.
<First embodiment>
FIG. 1 is a schematic cross-sectional view showing the configuration of the optical recording medium in the first embodiment of the present invention. In the optical recording medium 21 according to the first embodiment, the servo pit pattern 3 is formed on the first substrate 1 made of polycarbonate resin or glass, and the servo pit pattern 3 is coated with aluminum, gold, platinum or the like. Thus, the reflective film 2 is provided. In FIG. 1, the servo pit pattern 3 is formed on the entire surface of the first substrate 1, but may be formed periodically. The height of the servo pit pattern 3 is normally 1,750 mm (175 nm), which is sufficiently smaller than the thicknesses of the substrate and other layers.

The first gap layer 8 is formed by applying a material such as an ultraviolet curable resin on the reflective film 2 of the first substrate 1 by spin coating or the like. The first gap layer 8 is effective for protecting the reflective film 2 and adjusting the size of the hologram generated in the holographic recording layer 4. That is, in the holographic recording layer 4, it is necessary to form an interference region between the recording reference light and the information light with a certain size, so that the first gap layer is formed between the holographic recording layer 4 and the servo pit pattern 3. It is effective to provide 8.
A filter layer 6 is provided on the first gap layer 8, and an optical recording medium 21 is configured by sandwiching the holographic recording layer 4 between the filter layer 6 and a second substrate 5 (made of polycarbonate resin or glass). The

In FIG. 1, the filter layer 6 transmits only red light and does not transmit light of other colors. Therefore, since the information light, the recording and reproduction reference light are green or blue light, the light does not pass through the filter layer 6 and does not reach the reflection film 2 and becomes return light, which is emitted from the incident / exit surface A. Become.
The filter layer 6 is a multilayer deposited film in which high refractive index layers and low refractive index layers are alternately stacked.
The filter layer 6 composed of the multilayer deposited film may be directly formed on the first gap layer 8 by vacuum deposition, or a film having the multilayer deposited film formed on the substrate is punched into an optical recording medium shape and arranged. May be.

  The optical recording medium 21 in the present embodiment may be disk-shaped or card-shaped. In the case of a card shape, there is no need for the servo pit pattern. In this optical recording medium 21, the first substrate 1 is 0.6 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 2 to 3 μm, the holographic recording layer 4 is 0.6 mm, and the second substrate 5. Has a thickness of 0.6 mm, and the total thickness is about 1.9 mm.

  Next, the optical operation around the optical recording medium 21 will be described with reference to FIG. First, light (red light) emitted from the servo laser is reflected almost 100% by the dichroic mirror 13 and passes through the objective lens 12. Servo light is irradiated onto the optical recording medium 21 by the objective lens 12 so as to be focused on the reflective film 2. That is, the dichroic mirror 13 transmits light having a wavelength of green or blue, and reflects light having a wavelength of red almost 100%. The servo light incident from the light incident / exit surface A of the optical recording medium 21 passes through the second substrate 5, the holographic recording layer 4, the filter layer 6, and the first gap layer 8 and is reflected by the reflective film 2. Then, the light passes through the first gap layer 8, the filter layer 6, the holographic recording layer 4, and the second substrate 5 and is emitted from the incident / exit surface A again. The returned return light passes through the objective lens 12, is reflected almost 100% by the dichroic mirror 13, and servo information is detected by a servo information detector (not shown). The detected servo information is used for focus servo, tracking servo, slide servo, and the like. Since the hologram material constituting the holographic recording layer 4 is not sensitive to red light, it is assumed that servo light passes through the holographic recording layer 4 or that the servo light is irregularly reflected by the reflective film 2. However, the holographic recording layer 4 is not affected. In addition, since the return light of the servo light reflected by the reflective film 2 is reflected almost 100% by the dichroic mirror 13, the servo light is detected by the CMOS sensor or the CCD 14 for detecting the reproduced image. In addition, there is no noise with respect to the reproduction light.

  Further, the information light and the recording reference light generated from the recording / reproducing laser pass through the polarizing plate 16 to become linearly polarized light, pass through the half mirror 17 and pass through the quarter-wave plate 15 at a time. Become polarized. The optical recording medium 21 is irradiated with information light and recording reference light through the dichroic mirror 13 so as to generate an interference pattern in the holographic recording layer 4 by the objective lens 12. The information light and the recording reference light enter from the incident / exit surface A and interfere with each other in the holographic recording layer 4 to generate an interference pattern there. Thereafter, the information light and the recording reference light pass through the holographic recording layer 4 and enter the filter layer 6, but are reflected between the bottom of the filter layer 6 and become return light. That is, the information light and the recording reference light do not reach the reflective film 2. This is because the filter layer 6 is a multilayer deposited layer in which a plurality of high refractive index layers and low refractive index layers are alternately stacked, and has a property of transmitting only red light.

<Second Embodiment>
FIG. 2 is a schematic cross-sectional view showing the configuration of the optical recording medium in the second embodiment of the present invention. The optical recording medium 22 according to the second embodiment is the same as the first embodiment except that the second gap layer 7 is provided between the filter layer 6 and the holographic recording layer 4.
The second gap layer 7 has a point where information light and reproduction light are focused. If this area is filled with a photopolymer, excessive consumption of monomers due to overexposure occurs, resulting in a decrease in multiple recording capability. Therefore, it is effective to provide a non-reactive and transparent second gap layer.

  In the optical recording medium 22 of the second embodiment, the first substrate 1 is 1.0 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 3 to 5 μm, the second gap layer 7 is 70 μm, and holographic recording. The layer 4 has a thickness of 0.6 mm, the second substrate 5 has a thickness of 0.4 mm, and the total thickness is about 2.2 mm.

The shape of the optical recording medium 22 in the second embodiment may be a disk shape or a card shape, and is formed in the same manner as in the first embodiment.
The optical operation around the optical recording medium 22 in the second embodiment is the same as the optical operation around the optical recording medium 21 in the first embodiment.

(Optical recording method and optical reproduction method)
The optical recording method of the present invention irradiates the optical recording medium of the present invention with coherent information light and reference light, forms an interference image with the information light and the reference light, Recording is performed on a holographic recording layer of an optical recording medium.
In this case, the information light and the reference light are irradiated to the optical recording medium so that the optical axis of the information light and the optical axis of the reference light are coaxial, and the information light and the reference light are generated by interference. It is preferable to record the interference image on the holographic recording layer of the optical recording medium.
The optical reproduction method of the present invention is characterized in that information is reproduced by irradiating the interference pattern recorded on the holographic recording layer with the reference light by the optical recording method of the present invention.

In the optical recording method of the present invention, as described above, the information light having a two-dimensional intensity distribution and the information light and the reference light having a substantially constant intensity are overlapped in the photosensitive holographic recording layer. In addition, information is recorded by generating a distribution of optical characteristics inside the holographic recording layer using an interference pattern formed by them. On the other hand, when reading (reproducing) the written information, only the reference light is irradiated to the holographic recording layer in the same arrangement as in recording, and the intensity corresponding to the optical characteristic distribution formed inside the holographic recording layer The reproduced light having the distribution is emitted from the holographic recording layer.
Here, the optical recording method and reproducing method of the present invention are suitably performed using the optical recording / reproducing apparatus of the present invention described below.

An optical recording / reproducing apparatus used in the optical recording method and reproducing method of the present invention will be described with reference to FIG.
The optical recording / reproducing apparatus 100 controls a spindle 81 to which the optical recording medium 20 is attached, a spindle motor 82 for rotating the spindle 81, and the spindle motor 82 so as to keep the rotational speed of the optical recording medium 20 at a predetermined value. A spindle servo circuit 83.
The optical recording / reproducing apparatus 100 records information by irradiating the optical recording medium 20 with information light and recording reference light, and irradiates the optical recording medium 20 with reproduction reference light for reproduction. A pickup 31 for detecting light and reproducing information recorded on the optical recording medium 20 and a drive device 84 that can move the pickup 31 in the radial direction of the optical recording medium 20 are provided.

  The optical recording / reproducing apparatus 100 uses a detection circuit 85 for detecting a focus error signal FE, a tracking error signal TE, and a reproduction signal RF from an output signal of the pickup 31, and a focus error signal FE detected by the detection circuit 85. Based on this, the actuator in the pickup 31 is driven to move the objective lens (not shown) in the thickness direction of the optical recording medium 20 to perform focus servo, and the tracking error signal detected by the detection circuit 85. Based on TE, a tracking servo circuit 87 that drives an actuator in the pickup 31 to move the objective lens in the radial direction of the optical recording medium 20 to perform tracking servo, a tracking error signal TE, and a command from a controller to be described later. Drive 84 controlled by a and a slide servo circuit 88 for performing a slide servo for moving the pickup 31 in the radial direction of the optical recording medium 20.

The optical recording / reproducing apparatus 100 further decodes output data of a later-described CMOS or CCD array in the pickup 31 to reproduce data recorded in the data area of the optical recording medium 20 or reproduce from the detection circuit 85. A signal processing circuit 89 that reproduces a basic clock and discriminates an address from the signal RF, a controller 90 that controls the entire optical recording / reproducing apparatus 100, and an operation unit 91 that gives various instructions to the controller 90 It has.
The controller 90 inputs the basic clock and address information output from the signal processing circuit 89, and controls the pickup 31, spindle servo circuit 83, slide servo circuit 88, and the like. The spindle servo circuit 83 receives the basic clock output from the signal processing circuit 89. The controller 90 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes a program stored in the ROM using the RAM as a work area. The function of the controller 90 is realized.

  Since the optical recording / reproducing apparatus used in the optical recording method and reproducing method of the present invention uses the optical recording medium of the present invention, recording sensitivity is high and high-density recording can be realized.

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

Example 1
-Preparation of composition for holographic recording-
2.344 g of 2- (1-ethylpropyl) oxazoline (synthetic product), 0.15 g of methyl trifluoromethanesulfonate (manufactured by Aldrich), 2,4,6-tribromophenyl acrylate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.423 g and 0.086 g of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals, Irgacure 784) were mixed under a nitrogen stream to prepare a holographic recording composition.

(Example 2)
-Preparation of composition for holographic recording-
In Example 1, except that 4-344 g of 2-propyloxazoline (synthetic product) was used instead of 4.344 g of 2- (1-ethylpropyl) oxazoline (synthetic product), holo A graphic recording composition was prepared.

(Example 3)
-Preparation of composition for holographic recording-
Example 1 is the same as Example 1 except that 4.344 g of 2- (5-ethylpentyl) oxazoline (synthetic product) was used instead of 4.344 g of 2- (1-ethylpropyl) oxazoline (synthetic product). Similarly, a holographic recording composition was prepared.

Example 4
-Preparation of composition for holographic recording-
In Example 1, 2.172 g of 2- (1-ethylpropyl) oxazoline (synthetic product) and 2-heptyloxazoline (synthetic product) 2 instead of 4.344 g of 2- (1-ethylpropyl) oxazoline (synthetic product) A holographic recording composition was prepared in the same manner as in Example 1 except that .172 g was used.

(Comparative Example 1)
-Preparation of composition for holographic recording-
31.5 g of biscyclohexylmethane diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 61.2 g of polypropylene oxide triol (molecular weight 1,000), 2.5 g of tetramethylene glycol, 3.1 g of 2,4,6-tribromophenyl acrylate, light A polymerization initiator (Ciba Specialty Chemicals, Irgacure 784) 0.69 g and dibutyl dilaurate tin (Wako Pure Chemical Industries, Ltd.) 1.01 g were mixed under a nitrogen stream to prepare a holographic recording composition. Prepared.

(Examples 5 to 8 and Comparative Example 2)
-Production of optical recording media-
An antireflection treatment was performed on one surface of 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 0.1%, and a first substrate was produced.
Aluminum vapor deposition was performed on one surface of 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 90%, and a second substrate was produced.
Next, a transparent polyethylene terephthalate sheet having a thickness of 500 μm was provided as a spacer on the surface of the first substrate not subjected to antireflection treatment.
Next, each of the holographic recording compositions of Examples 1 to 4 and Comparative Example 1 was placed on the first substrate, and the aluminum-deposited surface of the second substrate was aired on the holographic recording composition. It bonded so that it might not be caught, and was bonded with the 1st board | substrate and the 2nd board | substrate via the spacer. Then, each optical recording medium was produced by leaving it at 80 ° C. for 4 hours (dry sample).

-Preparation of samples for water impact assessment-
Each holographic recording composition of Examples 1 to 4 and Comparative Example 1 was placed in a 200 mL beaker and allowed to stand for 24 hours under a constant temperature and constant humidity condition of a temperature of 30 ° C./humidity of 90%. Using these, each optical recording medium was prepared (wet sample) in the same manner as the dry sample preparation.

<Recording and evaluation>
For each of the produced optical recording media, a collinear hologram recording / reproduction tester (manufactured by Pulstec Industrial Co., Ltd., SHOT-1000) is used to write a hologram at the recording spot size (diameter 200 μm) at the focal position of the recording hologram. Thus, the sensitivity (recording energy) was measured and the influence of water was evaluated. The results are shown in Table 1.

-Measurement of sensitivity-
With respect to the produced dry samples of the respective optical recording media, the irradiation light energy (mJ / cm ² ) during recording was changed, and the change in error probability (BER) of the reproduction signal was measured. Usually, as the recording light power increases, the luminance (μ _ON ) of the reproduction signal increases and the BER of the reproduction signal tends to gradually decrease. Here, as the sensitivity, the irradiation light energy when the signal is μ _ON = 200 is defined as the recording sensitivity of the optical recording medium.

-Evaluation of water effect-
The brightness of the recording was evaluated with a collinear hologram recording / reproduction tester (manufactured by Pulstec Industrial Co., Ltd., SHOT-1000) using the dry sample and the wet sample of each of the produced optical recording media. Assuming that the dry sample recording brightness is μ _ON (D) and the wet sample recording brightness is μ _ON (W), the difference in recordability due to the influence of water is expressed by the following formula 1 for brightness. expressed.
<Formula 1>
Retention rate (%) = (μ _ON (W) / μ _ON (D)) × 100

  Table 1 shows the glass transition temperatures (Tg) of the polymers obtained by ring-opening polymerization of the compounds having an oxazoline ring in Examples 1 to 4. Tg is measured by a differential scanning calorimeter (DSC) (Shimadzu Corporation, DSC-60).

From the results in Table 1, it can be seen that the holographic optical recording compositions of Examples 1 to 4 are superior in water stability to the holographic recording composition of Comparative Example 1. In order to manufacture a holographic optical recording medium having a constant quality, it is a great advantage that humidity adjustment in the air is not required in the manufacturing process.

The holographic recording composition of the present invention is excellent in stability against water and can efficiently produce a holographic optical recording medium, and is therefore suitable for various volume hologram type optical recording media capable of high-density image recording. Used for.
Since the optical recording medium of the present invention has a holographic recording layer made of a holographic recording composition excellent in water stability, various volume hologram type light beams that are excellent in manufacturing stability and capable of high-density image recording. It is suitably used for a recording medium.

FIG. 1 is a schematic sectional view showing an example of an optical recording medium according to the first embodiment of the present invention. FIG. 2 is a schematic sectional view showing an example of an optical recording medium according to the second embodiment of the present invention. FIG. 3 is an explanatory diagram showing an example of an optical system around the optical recording medium according to the present invention. FIG. 4 is a block diagram showing an example of the overall configuration of an optical recording / reproducing apparatus equipped with the optical recording medium of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 Reflecting film 3 Servo bit pattern 4 Holographic recording layer 5 2nd board | substrate 6 Filter layer 7 2nd gap layer 8 1st gap layer 12 Objective lens 13 Dichroic mirror 14 Detector 15 1/4 wavelength plate DESCRIPTION OF SYMBOLS 16 Polarizing plate 17 Half mirror 20 Optical recording medium 21 Optical recording medium 22 Optical recording medium 31 Pickup 81 Spindle 82 Spindle motor 83 Spindle servo circuit 84 Drive device 85 Detection circuit 86 Focus servo circuit 87 Tracking servo circuit 88 Slide servo circuit 89 Signal processing Circuit 90 Controller 91 Scanning section 100 Optical recording / reproducing apparatus A Input / output surface FE Focus error signal TE Tracking error signal RF reproduction signal

Claims (6)

Including a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring, a radical polymerizable monomer, and a photopolymerization initiator,
A holographic recording composition, wherein a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring has a repeating unit represented by the following general formula (1).
However, in said general formula (1), R represents a C3-C7 alkyl group. The alkyl group may have a substituent. n represents an integer of 1 or more. The holographic recording composition according to claim 1, wherein the compound having an oxazoline ring is represented by the following general formula (2).
However, in said general formula (2), R represents a C3-C7 alkyl group. The alkyl group may have a substituent. The composition for holographic recording according to any one of claims 1 to 2, wherein a glass transition temperature (Tg) of a polymer obtained by ring-opening polymerization of a compound having an oxazoline ring is -20 ° C or higher and 30 ° C or lower. A method for producing a holographic recording composition according to any one of claims 1 to 3, comprising a step of ring-opening polymerization of a compound having an oxazoline ring by heat. Manufacturing method. An optical recording medium comprising a holographic recording layer comprising the holographic recording composition according to claim 1. The optical recording medium according to claim 5, comprising a first substrate, a filter layer, a holographic recording layer, and a second substrate.