JP2002539475A - Holographic recording material - Google Patents

Abstract

  (57) [Summary] The present invention relates to novel holographic recording materials suitable for use in the field of photoaddressable polymers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a holographic mass storage medium.
The present invention relates to a recording material for a medium storage medium, its production, and its use in recording large quantities of holograms.

[0002] Holography uses two types of coherent light.
beams) A method in which an image of an object can be generated on a suitable storage material using the interference between the [signal wave and the reference wave] and the image can be read again using light (reading light). (D. Gabor, Nature 151, 45
4 (1948); H. Farath, Advances in Holog
Raphy, Vol. 3, Marcel Decker (1977), H.C. M. Smi
th, Holographic Recording Materials, S
springer (1977)). On the one hand, by changing the angle between the signal wave and the reference wave and, on the other hand, by changing the holographic storage material, a number of holograms are transferred to one and the same specimen position in said material.
Can be written to and finally read again individually. The coherent light source used is generally laser light. A very wide variety of materials have been described as such storage materials, for example inorganic crystals, for example LiNbO ₃
Organic polymers (eg, M. Eich, JH Wendorf).
f, Makromol. Chem., Rapid Commun. 8,467 (
1987); H. Wendorff, M .; Eich, Mol. Cryst.
Liq. Cryst. 169, 133 (1989)) or a photopolymer (p
photopolymers) (Uh-Sock Rhee et al., Applied
Optics, 34 (5), 846 (1995)).

However, such materials do not yet meet all the requirements required for holographic storage media. In particular, the stability of the recorded hologram is not sufficient. Multiple recording, if possible, is generally, if at all, only to a limited degree, because when a new hologram is recorded, it is written over a hologram that has already been recorded. Is erased. This is especially true for inorganic crystals, which have been subjected to complex heat treatments to compensate for such stability problems. Photopolymers, on the other hand, exhibit problems with shrinkage, which can adversely affect holographic imaging properties.

Further, a material in which a recorded hologram exhibits a high degree of stability is also used, for example, in EP 0
No. 704 513 and German Application DE-A-19703132 (not yet published).

However, such materials have high optical densities, and such materials are used to produce holographic mass storage media as required when attempting to store a large number of holograms in a storage material. Is impossible.

[0006] It is therefore desirable to store a large number of holograms in one sample location of the recording material in a manner such that they exhibit long-term stability, which are suitable for use in the production of sufficiently thick holographic mass storage media. There was a need for a material that would enable it. With previously known materials, storing a large number of holograms in one location, one after the other, gradually erases the holographically stored information: holograms recorded later Addresses the same molecule that was used in the construction of the hologram previously recorded, resulting in the loss of information in the old hologram after only a few additional recording steps. .

Therefore, the present invention comprises at least one dye whose spatial arrangement changes when a hologram is recorded and optionally at least one shape-anisotropic group (shap).
Provided is a recording material for a holographic mass storage medium, which may contain e-anisotropic grouping, characterized in that two or more holograms can be recorded at one sample position.

This can preferably be such that it can no longer be excited by electromagnetic radiation, ie the absorption behavior changes, in particular the sensitivity to actinic light before the recording of the first hologram in each case. Reduction on a basis, preferably 10% to 100% reduction, more preferably 50% to 100% reduction,
It is most preferably carried out by making the dye in the at least one dye whose spatial arrangement changes in such a manner as to reduce it by 90% to 100%.

However, the dye also has a reduced absorption behavior, in particular its sensitivity to actinic radiation, as it is flipped in a direction perpendicular to the direction of polarization of the actinic light so that the longitudinal axis of the molecule is 10 ° to 90 °, preferably 50 ° to 90 °, more preferably 75 ° to 90 °, and most preferably 85 ° to 9 ° for the polarization direction of
It may decrease at the point where it comes to be located at an angle of 0 °.

In such a manner, it is possible to successfully carry out recording several holograms at one sample position, ie to ensure that the information of the old hologram is not completely erased. it can.

[0011] The change in the excitation behavior of electromagnetic radiation when a hologram is recorded as described above can be achieved by using a dye that causes a change in spatial arrangement in the state of a polymeric or oligomeric amorphous organic material.

[0012] The use of these types of materials, when recording holograms, can result in holograms previously recorded on the material being unacceptably erased or completely damaged, as a whole. It can be prevented from even being overwritten.

Unacceptable attenuation means that, from a measurement technology point of view, the remaining information can no longer be resolved with respect to background noise.

The information is stored holographically. For this purpose, two types of coherent polarized light are caused to interfere on the specimen.

[0015] Such dyes change their spatial position within the polymer or oligomer layer when exposed to actinic light. A plane [incident plane (incident plane)] formed by connecting the two types of recording light beams with the longitudinal axis of the molecule at the time of exposure.
e) a dye oriented in the direction of] can no longer be excited by the light beam if the plane of polarization of the light beam is perpendicular to the plane of incidence. Information (holograms) recorded on such dyes during the recording process is protected against changes that occur during the next hologram recording process. Dyes that are not perfectly perpendicular to the polarization direction of the light beam but form an angle θ that is not 90 ° to the polarization direction will be further addressed during the next hologram exposure. However, the probability of reorientation of such dyes, and in particular the photosensitivity of such dyes, decreases as the angle of the longitudinal axis of the molecule approaches the position of 90 °.

The determination of the longitudinal axis of a molecule can be performed, for example, by using a molecular model (molecular model).
ling) (eg, CERIUS ² )
orm).

For example, polarized absorption spectroscopy (polarized absorption sp.
investigation: ie UV / VIS spectrometer (eg GARY 4)
G, UV / VIS spectrometer) by testing a sample previously exposed to actinic light within the absorption spectrum range of the dye by placing it between two polarizers. Will result in whether or not will undergo reorientation after exposure to actinic light. If the intensity of the absorbance changes as a function of the angle of the sample when the sample is rotated at right angles around the sample with the polarizer positioned in an appropriate position, e.g., crossed, the dye will reorient. This means that the results can be clearly measured.

When several holograms are to be recorded, various multiplexing processes (multiple holograms) are required.
iplex processes, such as angular multiplexing
plexing), wavelength multiplexing, phase multiplexing, shift multiplexing, peristrophic multiplexing, and the like.

One measure of the sensitivity to actinic light is holographic sensitivity. this,
For example, a holographic growth curve (holographic growth c)
urve), that is, from a curve of diffraction efficiency (= diffraction intensity based on the incident intensity of the reading laser) which occurs as a function of the energy stored by the recording light beam. This sensitivity is defined as the root slope (normalized to the thickness of the storage medium) of the diffraction efficiency according to its stored energy.

The present invention provides a recording laser having a wavelength of ≦ 2, preferably ≦ 1, more preferably ≦ 0.3.
Recording material for a holographic mass storage medium having an optical density of In this way, actinic light is transmitted uniformly through the storage medium.
and a thick hologram can be produced. The measurement of light density is performed using a commercial UV / VIS spectrometer (eg, CARY, 4G, UV / VIS).
(VIS spectrometer).

[0021] The recording material according to the present invention is preferably irradiated thi.
ckness) ≧ 01. mm, more preferably ≧ 0.5 mm, even more preferably ≧ 1 mm, and most preferably 5 cm or less.

The group that interacts with electromagnetic radiation is a dye. Thus, the material according to the invention contains at least one dye. The electromagnetic radiation is preferably laser light, preferably in the wavelength range 390 to 800 nm, more preferably in the range 400 to 650 nm,
Most preferably, it is a laser beam in the range of 510 to 570 nm.

In reading, the recording material is not exposed to two types of coherent light (as is the case with recording light), but is exposed to only one type of light, the reading light. The wavelength of the reading light beam is preferably longer than the wavelengths of the signal wave and the reference wave, for example, 70 to 500 nm longer. However, it is also possible to read using the wavelength of the recording laser, especially when a holographic mass recording medium is used commercially. However, for this purpose, in the reading process, the energy of the reading light beam is reduced by lowering the exposure intensity or shortening the exposure time or reducing the exposure intensity and shortening the exposure time.

The adjustment of the light density of the recording material according to the invention is carried out using two parameters: a) the molar extinction coefficient (mola) of the dye in the dye present in at least one type.
and / or b) at least one present in the form of a polymeric or oligomeric organic material
The concentration of the dye in the type of dye.

The dye exhibiting a low extinction coefficient is, for example, a dye having a non-polar and / or slightly polarizable structure. Such dyes may originate, for example, from the class of anthraquinone, stilbene, azastilbene, azo or methine dyes. Azo dyes are preferred. Azo dyes having an absorption maximum in the ππ * band equal to or less than 400 nm, more preferably less than 400 nm, are particularly preferred.

The azo dye is, for example, represented by the following formula (I)

[0027]

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Wherein X ¹ and X ² are the same or similar, R ¹ and R ² independently of one another represent hydrogen or a non-ionic substituent, and m and n Independently represents an integer of 0 to 4, preferably an integer of 0 to 2].

X ¹ and X ² are both atom types having the same or similar electronic structure (a
They are the same or similar because they are linked through atom types or atom groups.

As a measure of the similarity of the electronic structure of the atom type or group, for example, Hammett
Constants can be used.

X¹And X^TwoIs preferably each -X¹'-R^ThreeAnd -X^Two'-R^FourRepresents
X¹'And X^Two'Is a direct bond, -O-, -S-,-(N-R^Five)-, -C (R⁶R ⁷ )-,-(C = O)-,-(CO-O)-,-(CO-NR^Five)-,-(SO_Two
)-,-(SO_Two-O)-,-(SO_Two-NR^Five)-,-(C = NR⁸)-Or-
(CNR⁸-NR^Five)-, R^Three, R^Four, R^FiveAnd R⁸Are, independently of one another, hydrogen, C₁To C₂₀-Alkyl,
C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C₂₀-Alkenyl, C₆To C_Ten-Ant
, C₁To C₂₀-Alkyl- (C = O)-, C_ThreeTo C_Ten-Cycloalkyl-
(C = O)-, C_TwoTo C₂₀-Alkenyl- (C = O)-, C₆To C_Ten-Ally
Ru- (C = O)-, C₁To C₂₀-Alkyl- (SO_Two)-, C_ThreeTo C_Ten-Shiku
Low alkyl- (SO_Two)-, C_TwoTo C₂₀-Alkenyl- (SO_Two)-Or C₆Or
La C_Ten-Aryl- (SO_Two)-, Or X¹'-R^ThreeAnd X^Two'-R^FourIs hydrogen, halogen, cyano, nitro, CF_ThreeOr
CCl_ThreeMay be represented by R⁶And R⁷Are, independently of one another, hydrogen, halogen, C₁To C₂₀-Alkyl,
C₁To C₂₀-Alkoxy, C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C₂₀-Al
Kenyl or C₆To C_Ten-Represents aryl.

Nonionic substituents include halogen, cyano, nitro, C₁To C₂₀-Alkyl, C₁ To C₂₀-Alkoxy, phenoxy, C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C ₂₀ -Alkenyl or C₆To C_Ten-Aryl, C₁To C₂₀-Alkyl- (C =
O)-, C₆To C_Ten-Aryl- (C = O)-, C₁To C₂₀-Alkyl- (S
O_Two)-, C₁To C₂₀-Alkyl- (C = O) -O-, C₁To C₂₀-Alkyl
-(C = O) -NH-, C₆To C_Ten-Aryl- (C = O) -NH-, C₁From
C₂₀-Alkyl-O- (C = O)-, C₁To C₂₀-Alkyl-NH- (C = O
)-Or C₆To C_Ten-Aryl-NH- (C = O)-
It is.

Conversely, the alkyl, cycloalkyl, alkenyl and aryl groups can be the radicals halogen, cyano, nitro, C ₁ -C ₂₀ -alkyl, C ₁ -C ₂₀ -alkoxy, C ₃
From C ₁₀ - cycloalkyl, C ₂ from C ₂₀ - alkenyl or C ₆ C ₁₀ - may be substituted with up to three groups of the aryl and the alkyl and alkenyl groups have straight-chain or branched Is also good.

Halogen is to be understood as being fluorine, chlorine, bromine and iodine, in particular fluorine and chlorine.

The recording material according to the invention is preferably a polymeric or oligomeric amorphous organic material, more preferably a polymer having side chains, and more preferably a block copolymer and / or a graft polymer It is.

The main chain of the polymer having such side chains is derived from the following basic structure: polyacrylate, polymethacrylate, polysiloxane, polyurea, polyurethane, polyester or cellulose. Polyacrylates and polymethacrylates are preferred.

The block copolymer is made up of a plurality of blocks, at least one of said blocks containing the copolymer system described above. The other blocks are replaced with the functional block to adjust the required light density.
ck) which serves to dilute the non-functionalized (non-functionalized)
) Consist of a polymer structure. The extent of the functional block is less than the wavelength of the light, preferably less than 200 nm, more preferably less than 100 nm.

The polymerization of such block copolymers can be carried out, for example, by free-radical or anionic polymerization or any other suitable polymerization method followed by any polymer-like reaction (polym
er-analogous reaction) or a combination of the above methods. The homogeneity of this system
) Ranges from less than 2.0, preferably less than 1.5. When the block copolymer is obtained by free radical polymerization, the molecular weight of the block copolymer reaches a value in the range of 50,000, and when anionic polymerization is used, the molecular weight can be adjusted to a value exceeding 100,000.

Dyes, in particular azo dyes of the formula (I), are generally added to such polymer structures.
Is covalently bonded through a spacer. In that case, for example, X ¹ (Or X^Two) Represents such a spacer, in particular X¹'-(Q¹)_i-T¹-S¹ Represents a spacer having the meaning of-, where X¹'Is as defined above, Q¹Is -O-, -S-,-(N-R^Five)-, -C (R⁶R⁷)-,-(C = O)-
,-(CO-O)-,-(CO-NR^Five)-,-(SO_Two)-,-(SO_Two-O)
−, − (SO_Two-NR^Five)-,-(C = NR⁸)-,-(CNR⁸-NR^Five) −, −
(CH_Two)_p-, P- or mC₆H_Four− Or expression

[0040]

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Represents a divalent group represented by [0041], i is an integer of 0 to 4, where, i> 1 of the case may have the meanings which the individual radicals Q ¹ is different, T ¹ is, - (CH _{2) p} - represents, here, in this chain -O -, - NR ⁹ - or -
OSiR ¹⁰ ₂ O— may be interrupted, S ¹ represents a direct bond, —O—, —S— or —NR ⁹ —, p is 2 to 12, preferably 2 to 8, more preferably Represents an integer from 2 to 4, R ⁹ represents hydrogen, methyl, ethyl or propyl; R ¹⁰ represents methyl or ethyl; and R ⁵ to R ⁸ are as defined above. .

In this case, suitable dye monomers for the polyacrylate or polymethacrylate are of the formula (II)

[0043]

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Wherein R represents hydrogen or methyl, and the other groups are as defined above.

Particularly suitable monomers of the formula (II) are for example:

[0046]

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[0047]

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[0048]

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The polymeric or oligomeric amorphous organic material according to the present invention may have a shape-anisotropic group in addition to the dye, for example, the dye represented by the formula (I). Such groups are also commonly covalently attached to the polymer structure through a spacer.

The shape anisotropic group is, for example, a compound represented by the formula (III)

[0051]

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[Wherein, Z is a formula

[0053]

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Wherein A is O, S or N—C₁To C_FourX represents alkyl;^ThreeIs -X^Three'-(Q^Two)_j-T^Two-S^Two-Represents X^FourIs X^Four'-R¹³X^Three'And X^Four'Are, independently of one another, a direct bond, -O-, -S-,-(N-R^Five
)-, -C (R⁶R⁷)-,-(C = O)-,-(CO-O)-,-(CO-NR ^Five )-,-(SO_Two)-,-(SO_Two-O)-,-(SO_Two-NR^Five)-,-(C =
NR⁸)-Or-(CNR⁸-NR^Five)-, R^Five, R⁸And R¹³Are, independently of one another, hydrogen, C₁To C₂₀-Alkyl, C_ThreeOr
La C_Ten-Cycloalkyl, C_TwoTo C₂₀-Alkenyl, C₆To C_Ten-Aryl,
C₁To C₂₀-Alkyl- (C = O)-, C_ThreeTo C_Ten-Cycloalkyl- (C =
O)-, C_TwoTo C₂₀-Alkenyl- (C = O)-, C₆To C_Ten-Aryl- (
C = O)-, C₁To C₂₀-Alkyl- (SO_Two)-, C_ThreeTo C_Ten-Cycloal
Kill-(SO_Two)-, C_TwoTo C₂₀-Alkenyl- (SO_Two)-Or C₆To C_Ten -Aryl- (SO_Two)-Or X^Four'-R¹³Is hydrogen, halogen, cyano, nitro, CF_ThreeOr CCl_ThreeRepresents
Well, R⁶And R⁷Are, independently of one another, hydrogen, halogen, C₁To C₂₀-Alkyl,
C₁To C₂₀-Alkoxy, C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C₂₀-Al
Kenyl or C₆To C_TenY represents a single bond, -COO-, OCO-, -CONH-, -NHCO-, -CON.
(CH_Three)-, -N (CH_Three) CO-, -O-, -NH- or -N (CH_Three)-
Represents R¹¹, R¹², R^FifteenAre independently of one another hydrogen, halogen, cyano, nitro, C₁
To C₂₀-Alkyl, C₁To C₂₀-Alkoxy, phenoxy, C_ThreeTo C_Ten−
Chloroalkyl, C_TwoTo C₂₀-Alkenyl or C₆To C_Ten-Aryl, C₁Or
La C₂₀-Alkyl- (C = O)-, C₆To C_Ten-Aryl- (C = O)-, C₁ To C₂₀-Alkyl- (SO_Two)-, C₁To C₂₀-Alkyl- (C = O) -O-
, C₁To C₂₀-Alkyl- (C = O) -NH-, C₆To C_Ten-Aryl- (C
ＯO) —NH—, C₁To C₂₀-Alkyl-O- (C = O)-, C₁To C₂₀-A
Alkyl-NH- (C = O)-or C₆To C_Ten-Aryl-NH- (C = O)
-Represents q, r and s independently of one another an integer from 0 to 4, preferably from 0 to 2
, Q^TwoIs -O-, -S-,-(N-R^Five)-, -C (R⁶R⁷)-,-(C = O)-
,-(CO-O)-,-(CO-NR^Five)-,-(SO_Two)-,-(SO_Two-O-
)-,-(SO_Two-NR^Five)-,-(C = NR⁸)-,-(CNR⁸-NR^Five) −,
− (CH_Two)_p-, P- or mC₆H_Four− Or expression

[0055]

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[0056] represents a divalent group represented by, j represents an integer of 0 to 4, wherein, when the j> 1 may have a meaning that individual radicals Q ² different, T ² is, - (CH _{2) p} - represents, here, in this chain -O -, - NR ⁹ - or -
OSiR ¹⁰ ₂ O— may be interrupted; S ² represents a direct bond, —O—, —S— or —NR ⁹ —; p is 2 to 12, preferably 2 to 8, more preferably Represents an integer of 2 to 4, R ⁹ represents hydrogen, methyl, ethyl or propyl, and R ¹⁰ represents methyl or ethyl.]

In this case, a monomer having such a shape anisotropic group and suitable for polyacrylate or polymethacrylate is represented by the formula (IV)

[0058]

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Wherein R represents hydrogen or methyl, and the other groups are as defined above.

Particularly suitable shape-anisotropic monomers of the formula (IV) are, for example:

[0061]

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Conversely, the alkyl, cycloalkyl, alkenyl and aryl groups can be the radicals halogen, cyano, nitro, C ₁ -C ₂₀ -alkyl, C ₁ -C ₂₀ -alkoxy, C ₃
From C ₁₀ - cycloalkyl, C ₂ from C ₂₀ - alkenyl or C ₆ C ₁₀ - may be substituted with up to three groups of the aryl and the alkyl and alkenyl groups have straight-chain or branched Is also good.

Halogen is to be understood as fluorine, chlorine, bromine and iodine, in particular fluorine and chlorine.

The oligomers or polymers according to the invention may contain, in addition to such functional units, also units which serve mainly to reduce the percentage content of functional units, in particular dye units. In addition to having such a function, they may also affect other properties of the oligomer or polymer, such as glass transition temperature, liquid crystallinity, film forming properties, and the like.

Such monomers in the case of polyacrylates or polymethacrylates have the formula (V)

[0066]

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Wherein R represents hydrogen or methyl, and R ¹⁴ represents an optionally branched C ₁ -C ₂₀ -alkyl or group containing at least one further acrylic unit ] The acrylate or methacrylate represented by these.

In this case, the polyacrylates and polymethacrylates according to the invention are preferably the repeating units of the formula (VI), preferably of the formulas (VI) and (VII)
Or a repeating unit represented by the formulas (VI) and (VIII), or a repeating unit represented by the formulas (VI), (VII) and (VIII)

[0069]

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[These groups are as defined above.] The repeating unit represented by the following formula is contained as a repeating unit.

It is also possible to have several types of repeating units represented by the formula (VI) and / or the repeating units represented by the formulas (VII) and / or (VIII).

The relative ratios of VI, VII and VIII are as desired. The concentration of VI is VI
Is preferably from 0.1 to 100%, based on the mixture, depending on the extinction coefficient of the mixture. The ratio of VI to VII is 100: 0 to 1:99, preferably 100: 0 to 3
0:70, more preferably from 100: 0 to 50:50.

The main absorption band (π-π * band) exhibited by the dye represented by the formula (I) and the dye monomer represented by the formula (II) is located in a short wavelength region, and is represented by a secondary absorption band. (N-π *
Band) is located in the longer wavelength region. The molar extinction coefficient ε of the n-π * band is 40.
It is in the range of 0 to 5000 · 10 ³ cm ² / mol. The light density of an oligomer or polymer having an irradiation thickness of 0.1 mm and an estimated dye molar mass of 400 g / mol indicates that the content of the dye is ≦ 1.6% (ε = 5000) to ≦ 20% (ε = 400). ≦ 2.

The glass transition temperature T _g of the polymers and oligomers according to the invention is preferably at least 40 ° C. This glass transition temperature is, for example, Volmer,
Grundris der Makromolekularen Chemi
e, pp. 406-410 Springer-Verlag, Heidelber
g 1962.

The measured molecular weight of the polymers and oligomers according to the invention is between 5000 and 2,000,000, preferably between 8000 and 1,500,000 as a weight average determined by gel permeation chromatography (calibrated with polystyrene). is there.

The dye monomers of the formula (II) and optionally additionally the anisotropically shaped monomers of the formula (IV) and / or optionally additionally the monomers of the formula (V) Oligomer or polymer base system (base system)
When a free radical is bonded to ms), a graft polymer is formed. Such base systems may be very different types of polymers, for example polystyrene, poly (meth) acrylate, starch, cellulose, peptides and the like. The free radical bonding may be carried out by irradiation with light or by using a reactant that generates a radical, for example, t-butyl hydroperoxide, dibenzoyl peroxide, azodiisobutyronitrile, hydrogen peroxide / iron (II) salt, or the like. Can be implemented.

As a result of the structure of such polymers and oligomers, the components represented by formula (VI) may be linked to each other or the components represented by formulas (VI) and (VII) may be linked to each other. Adjusting the action results in an ordered state of the liquid crystal (order
The formation of films, foils, plates or cubes that are optically isotropic, transparent, and do not scatter light can be produced with reduced generation of (states). On the other hand, nevertheless, such intermolecular interactions can occur both in photochromic and non-photochromic (non-pho
Side groups are photochemically induced upon irradiation with light to cause co-directional reorientation (
strong enough to cause a cooperative, directed reorientation process.

The interaction force between the side groups of the repeating unit represented by the formula (VI) or between the side groups of the repeating units of the formulas (VI) and (VII) (
Interaction forces are preferably converted to other side groups [(VI) and / or by changing the form of the side groups of formula (VI) with light.
Or (VII)] is sufficient to provide a unidirectional (so-called joint) reorientation.

In the case of optically isotropic amorphous photochromic polymers, very high values of optical anisotropy can be induced (Δn up to 0.4).

When the polymer or oligomer is affected by actinic light, it results in an ordered state and is modified, thus adjusting the optical properties.

The light used is polarized light having a wavelength in the range of the absorption band of the repeating unit represented by the formula (VI), preferably in the range of the long wave n-π * band.

The preparation of the polymers and oligomers is carried out by methods known in the literature, for example DD 27
6 297, DE-A 3 808 430, Makromolekulare
Chemie, 187, 1327-1334 (1984), SU 8875.
74, Europ. Polym. 18,561 (1982) and Liq. Cr
yst. 2, 195 (1987).

A film without the need for using complex alignment processes using external fields and / or surface effects,
Foil, plate and cube can be produced. Spin coating them (
It may be applied to the substrate using spin coating, dipping, pouring or other coating methods (easy to adjust from a technical point of view) or it may be pressed or poured between two transparent plates. It can be produced as a self-supporting material, either by good or simple casting or extrusion. Also, by quenching the liquid crystal polymer or oligomer containing components of the meaning described above, ie, by cooling at a cooling rate of> 100 K / min or by rapidly removing the solvent, such films, foils, It is also possible to create plates and cubes.

300 ° C. or less, preferably 220 ° C., for the production process of the holographic mass storage medium
Hereinafter, it is preferable to include a step according to a usual injection molding process in a range of 180 ° C. or less.

The layer thickness is ≧ 0.1 mm, preferably ≧ 0.5 mm, more preferably ≧ 1 mm.
A particularly preferred method for producing layers in the millimeter range is the injection molding method.
In this method, the polymer melt may be forced through a nozzle and into a molding holder, from which it is removed after cooling.

A preferred method for producing the recording material, ie the polymer, according to the invention comprises a method in which at least one monomer is polymerized without further solvent, which polymerization is preferably a free radical polymerization, Preferably, the polymerization is initiated with a free radical initiator and / or UV light and / or heat.

The process is carried out at a temperature from 20 ° C. to 200 ° C., preferably from 40 ° C. to 150 ° C., more preferably from 50 ° C. to 100 ° C., most preferably about 60 ° C.

In a particular embodiment, AIBN is used as a free radical initiator.

It has frequently been found to be advantageous to use additional monomers, preferably liquid monomers. It is to be understood that such monomers are monomers that are liquid at the reaction temperature, such monomers being preferably olefinically unsaturated monomers, more preferably monomers based on acrylic acid and methacrylic acid. And most preferably methyl methacrylate.

The amount of the monomer of formula (II) included in the copolymer is preferably from 0.1 to 99.9% by weight, more preferably from 0.1 to 50% by weight, even more preferably from 0.1 to 9% by weight. 1
To 5% by weight, most preferably 0.5 to 2% by weight.

The holographic data storage method is, for example, LASER FOCUS WORL
D, Noverber 1996, page 81 et seq.

For hologram recording, the above-described polymer film is exposed to two coherent laser beams having wavelengths that provide the required light-induced reorientation. One light beam, the object wave, contains the optical information to be stored, such as a change in intensity resulting from the light beam passing through a two-dimensional grid of pixel structures (data pages). However, in principle, light diffracted, scattered or reflected by any two-dimensional or three-dimensional object can be used as the object wave. This object wave interferes with the second laser beam on the storage medium, the reference wave, which is generally a flat or circular wave. The resulting interference pattern causes the storage medium to modulate optical constants (refractive index and / or extinction coefficient).
ion). This modulation penetrates the entire illuminated area, in particular the entire thickness of the storage medium. Then, when the object wave is cut off and the medium is exposed only to a reference wave, such a modulated storage medium acts as a kind of reference wave grating.
The intensity distribution resulting from this diffraction is so memorable that it is no longer possible to distinguish whether the light is light coming from the object itself or not due to the diffraction of the reference wave. This corresponds to an intensity distribution derived from an object to be made.

In order to store various holograms at one sample position, various multiplexing processes such as wavelength multiplexing, shift multiplexing, phase multiplexing, peristrophic multiplexing and / or angular multiplexing are described below. And / or others. In the case of angular multiplexing, the angle between the storage medium and the reference wave [the hologram is related to
angles when stored in “angles”). Changing the angle to a certain degree makes the original hologram invisible (Bragg mismatch): when the storage medium no longer polarizes the incident reference wave, it is then possible to reconstruct the object. The angle at which it occurs depends on the thickness of the storage medium (and the modulation of the optical constants introduced in the medium): the angle that needs to be changed with respect to the reference wave is smaller the thicker the medium.

[0094] Such new angle configurations can be used to record additional holograms. This reading of the hologram also occurs exactly again in the angular arrangement (between the storage medium and the reference wave) used for recording the hologram.

Therefore, it is possible to record a plurality of holograms in the same place of the recording medium by gradually changing the angle between the recording medium and the recording light beam.

[0096] The polymer system described in the present specification does not erase the information (related to the hologram) previously stored in the storage medium when the next hologram is recorded, and saves the information in one place of the storage medium. A great advantage is that more than 6 holograms can be recorded, preferably more than 50, more preferably more than 100, even more preferably more than 500, and most preferably more than 1000 holograms. Having. What is to be stored is the data page resulting from the transmission of the liquid crystal display. Such a data page would have pixels 256x256, preferably pixels 512x
512, preferably 1024 x 1024 data pixels.

The invention also comprises a polymeric or oligomeric amorphous organic material comprising at least one group interacting with electromagnetic radiation and optionally containing at least one shape-anisotropic group. Also provided is a recording material for a holographic mass storage medium, wherein the light density is ≦ 2, preferably ≦ 1, more preferably ≦ 0.3. The recording material can be used for data storage in the form of an unsupported film or, preferably, in the form of a multilayer structure. The multilayer structure is, for example,
It is a sandwich type structure in which the actual recording medium is surrounded by at least one substrate. The substrate may be a transparent medium having high optical quality, such as a glass plate, a quartz plate or a polycarbonate plate. A high optical quality is understood to mean that the scattering factor, ie the quotient between the light scattered at the sandwich and the incident light, is 10 ^-4 or more, preferably 10 ^-5 or more, especially 10 ^-6 or more. It should be. This quotient can be determined through exposing the sample to a HeNe laser beam. Detection is performed using a CCD camera.

EXAMPLES Example 1 Preparation of Monomers:

[0099]

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A) 4- (2-Hydroxyethyloxy) benzoic acid While stirring 350 ml of ethanol, p-hydroxybenzoic acid was added to 13 ml of ethanol.
8 g and 0.5 g of KI are charged. A solution of 150 g of KOH in 150 ml of water is added dropwise. 88.6 g of ethylene chlorohydrin in 30
Add dropwise at -60 ° C over 30 minutes. The reaction mixture is stirred under reflux for 15 hours. Next, the solvent is first distilled off under normal pressure and then completely distilled off under vacuum. The residue is dissolved in one liter of water and then acidified with HCl. The precipitate is filtered off with suction and recrystallized from 1.8 l of water. After drying the product, it is recrystallized twice with ethanol. The yield is 46 g (25% of theoretical). 179.5 ° C. b) 4- (2-methacryloyloxyethyloxy) benzoic acid While stirring 150 ml of chloroform, 45 g of 4- (2-hydroxyethyloxy) benzoic acid, 180 ml of methacrylic acid, and p-toluenesulfonic acid were added thereto. Add 10 g and 10 g of hydroquinone and heat under reflux. Water generated during the reaction is separated by a water separator. The reaction mixture is diluted with 150 ml of chloroform, washed several times in each case with 100 ml of water and dried over Na ₂ SO ₄ . After the desiccant is filtered off, chloroform is distilled off using a rotary evaporator to reduce the chloroform to 2/3. After the precipitated product has been filtered off with suction, it is recrystallized twice from isopropanol. Yield 2
8 g (45% of theoretical yield). 146 ° C. c) 4- (2-methacryloyloxyethyloxy) benzoic acid chloride 25 g of 4- (2-methacryloyloxyethyloxy) benzoic acid and 80 m
Stir 1 l thionyl chloride and 0.5 ml DMF at room temperature for 30 minutes. The excess thionyl chloride is then first distilled off under moderate vacuum and then under high vacuum. The resulting acid chloride is then slowly crystallized at room temperature in a substantially quantitative yield. Elemental _{analysis: C 13 H 13 ClO 4 (} 268.7) calc: C58.11; H4.88; Cl13.19; measurements: C58.00; H4.90; Cl13.20. d) 4-Pivalinoylamino-4'-aminoazobenzene In 400 ml of THF are charged 36 g of 4,4'-diaminoazobenzene and 62 g of triethylamine. A solution of 23.2 g of pivalic acid chloride in 100 ml of THF is slowly added dropwise. After stirring the reaction mixture at room temperature for 2 hours, water is added thereto. The precipitate is filtered off and dried. 42 g of product are obtained. Chromatography (silica gel, toluene / ethyl acetate 1:
Further purification is carried out in 1). The yield is 8 g. 230 ° C. e) 4-Pivalinoylamino-4 ′-[p- (2-methacryloyloxyethyloxy) benzoylamino] azobenzene 4-Pivalinoylamino in 10 ml of N-methyl-2-pyrrolidone (NMP) at 50 ° C. After adding 1 g of -4'-aminoazobenzene, 1 ml of NMP
Of 1 g of 4- (2-methacryloyloxyethyloxy) benzoic acid into a 50 ° C. solution. The reaction mixture is stirred for 1 hour at said temperature and, after cooling, 200 ml of water are added. After the precipitate has been filtered off, 30 ml of methanol are stirred in at room temperature, the mother liquor is filtered off and the drying is carried out under vacuum. The yield is 1.2 g. Melting point 194 [deg.] C. λ _max = 378 nm (DMF); ε = 3700
0 l / (mol * cm).

Example 2 a) 32 g of N-benzoyl-p-phenylenediamine were added to a mixture of 210 ml of glacial acetic acid, 75 ml of propionic acid and 31 ml of concentrated hydrochloric acid at 3-5 ° C. 50g
Of nitrosylsulfuric acid (about 40%) was added dropwise at the above temperature over 1 hour. b) 16 g of m-toluidine was dissolved in 130 ml of glacial acetic acid. 0-5 ° C
The diazotization obtained in a) was added dropwise over 2 hours. The mixture was stirred overnight at room temperature. The resulting dye was filtered off with suction and suspended in 550 ml of water. PH is adjusted to 8.4 using soda
Up to. The dye was again filtered off with suction, washed with isopropanol and dried. formula

[0102]

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27 g (54.4% of theoretical yield) of the dye represented by was obtained. UV / VIS in dimethylformamide: λ _max = 416 nm. c) 5 g of the dye obtained in b) were dissolved at 50 ° C. in 20 ml of N-methylpyrrolidone. formula

[0104]

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3.5 g of the acid chloride represented by the formula was added. The mixture was stirred at 50 ° C. for 1.5 hours. Finally, after the addition of 20 ml of water, the resulting dye was filtered off with suction. This was stirred with 50 ml of isopropanol, filtered off with suction and dried. formula

[0106]

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6.2 g (73.4% of the theoretical yield) of the dye monomer represented by was obtained. UV / VIS in dimethylformamide: λ _max = 386 nm.

The dye monomers shown in the table below were prepared in a similar manner.

[0109]

[Table 1]

Example of Graft Polymer In 60 ml of water, P, a starch obtained from Avebe (Foxhol, NL)
8.7 g of erfectamyl A 4692 (86.3%) was added and dissolved at 86 ° C. 1.5 g of a 1% by weight aqueous solution of FeSO ₄ and 3% by weight of H ₂ O ₂
A mixture of 6.1 g of the aqueous solution was added. Stirring was performed at 86 ° C. for 15 minutes. next,
At this temperature, 12.5 g of methyl methacrylate has the formula

[0111]

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A solution formed by adding 1.4 g of the dye monomer represented by
A weight% aqueous solution of H ₂ O ₂ was simultaneously added dropwise over 90 minutes. After another 15 minutes at this temperature,
0.105 g of t-butyl hydroperoxide was added and stirring was carried out at 86 ° C. for another hour. The yellow fine dispersion was filtered through a 100 μm polyamide filter.

The dispersion was diluted 1:10 with water, applied to a glass plate, and dried. A KL 500 made by Schott is applied to the transparent pale yellow film attached to the glass plate.
Irradiation with polarized light (point diameter 6 mm) emitted from a cold light lamp was performed for 10 minutes. The irradiated spot located between the crossed polarizers could be seen brightly in a dark surrounding.

Example 3 Preparation of Holographic Material by Block Polymerization 10 g of methyl methacrylate were mixed with 1 mol% of the monomer represented by the formula (II) or the monomer of Example 2 and 2,2′-azoisobutyric acid nitrile. Was added to a glass ampoule, and dried argon was added to the solution.
Pour for a minute. The ampoule was sealed with a rubber stopper and cast at 60 ° C. for 7 days. A clear polymer cylinder was obtained. The polymer cylinder could be isolated by breaking the ampoule and removing the broken glass.
It was stored at 60 ° C. for another 2 weeks in order to remove residual methyl methacrylate and release the stress in the polymer block.

The PAP cylinder thus obtained was cut at a precision engineering workshop into plates having a diameter of 17 mm and a thickness of 1.9 mm and then polished. This plate shows the optical density according to the invention at the following important wavelengths: OD (532 nm) and OD (568 nm).

In a similar manner, a copolymer having an azo dye content of 10 mol% was obtained. In a similar manner, the content of other monomers is 1 mol% and the content of methyl methacrylate is 9%.
A 9 mol% copolymer is prepared.

Example 4 The polymer of Example 3 is applied to a glass substrate having a thickness of 150 μm by spin coating using a solution. The layer thickness at the measurement point located at the center of the substrate is 600 n
m. The level of the refractive index n of the polymer layer is measured in three spatial directions x, y (layer plane) and z (perpendicular to the layer) using a prism coupling method.
For this purpose, the base of the prism is brought into intimate contact with the polymer layer. The angle at which the polarization of the laser is incorporated into the layer and transmitted through it in a waveguide manner provides information about the refractive index at the wavelength of the light. When a signal drop on the detector causes a reflection, each incorporation (cou) occurs.
"pling in" is cleared (becomes clear).

The refractive index in this polarization direction can be measured by selecting the polarization of the laser so that it is perpendicular to the plane of incidence (s-polarization). the value of n _x and n _y can be determined according to the orientation of the substrate. The refractive index of the substrate showing the lower refractive index, the refractive index of the prism and the wavelength of the laser (λ = 633 nm) are also added to the calculation. If polarized light (p-polarized light) occurs at the plane of incidence, the value of _nz can be measured. For this purpose, it is necessary to match one of the two spatial directions, x or y, with the plane of incidence. Additionally, the index value ( _nx or _ny ) in the direction thus selected is also added to the calculation.

[0119] The samples for refractive indices n _x, n _y and n _z several exposure and revocation process before, measured during and after the course and the course. The polymer layer is irradiated with laser light having a wavelength of λ = 514 nm at normal incidence to be exposed. The intensity of this light is set to 200 mW / cm ² . This light is linearly polarized in the x direction. In this way, the cancellation of the orientation anisotropy induced in the xy plane is caused by polarized light in the y direction.

[0120] It, lambda = readily verifiable by measuring the refractive indices n _x, n _y and n _z of at the 633 nm. For this purpose, the sample is measured, for example, in the untreated state, after a 200 second exposure, after a 500 second exposure and after a 5000 second exposure.

Further information can be obtained by measuring the refractive indices n _x , _ny and _nz at λ = 633 nm after the first and second cancellation as well as after the second or further exposure for 5000 seconds. obtain.

The level of refractive index in each spatial direction is a measure of the average number of chromophores oriented in that direction, because it correlates with the induced polarization and it is primarily This is because it is composed of a high molecular weight polarizer that exists along the axis. Since _nx and _ny are originally the same, a macroscopically isotropic distribution exists on the xy plane. A small _nz value indicates that the orientation of the molecules is flat as a result of the manufacturing process. Orientation distribution gradually (orien
As a result of the occurrence of the transition, the number of chromophores located in the x-direction is reduced. This decrease in direction occurs in the statistical sense by increasing the other two spatial directions, y and z, by an equal fraction, which is due to the larger values of _ny and _nz. Can be read.
Birefringence n _y -n _x can again completely eliminated in the film plane. However, as further exposure or cancellation procedures are performed, the number of chromophores oriented in the z-direction in each of them increases. As a result, they can no longer be used in further (next) recording processes.

Example 5 The polymer formed from the monomers according to Example 2 is in the form of particles. This is applied to a glass substrate and heated to about 180 ° C. At this temperature the polymer melts. A spacer, such as a mylar film or glass fiber, is placed on the glass substrate and a cover glass is further placed. Such glass-polymer-glass sandwiches are used to produce layers ranging from 20 to 1000 μm.

Example 6 A 500 μm thick polymer film produced by the method of Example 5 is tested in a holographic structure. SHG Nd: YAG laser (53
2 nm) as a recording source. Spatial Light on the optical path of the object wave
Locate the Modulator (which constitutes a data mask with 1024 x 1024 pixels). The intensity ratio of the reference wave to the object wave is 7: 1 and the total power density falling on the sample is 200 mW / cm ² . Superimposing the reference and object waves so that their polarizations are perpendicular to the plane of incidence and they fall on the sample at an angle of 40 ° to each other, exposing the sample for 30 seconds, The hologram was recorded, and then the hologram was read by exposure using only the reference wave (exposure time: 10 ms). Changing the angle of the reference wave by 0.25 ° breaks the Bragg state and the original hologram can no longer be seen. A new hologram is recorded under such a new angle arrangement. This process is repeated 100 times. After each recording step, the corresponding reference angle (reference an)
By adjusting the gle), all of the previously recorded holograms were read, in addition to being able to read the hologram just recorded. 10
The information contained in all the holograms was retained even after the zero recording process was completed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09B 69/10 C09B 69/10 G03H 1/26 G03H 1/26 (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY) , KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, C U, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ , LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, S K, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Eikmans, Johannes Deutsche D-42781 Hahn Robert-Kotscho Jutrace 3 (72) Inventor Hagen, Liner Deutsche D. 51375 Leif Erkusen-Feliix-Hon-Roll-Shuitlerse 35 (72) Inventor Kostromine, Sergey Deutsche D.-53913 Shubysttal Katarinenshujtra -28 F term (reference) 2K008 DD11 FF07 4H006 AA01 AB46 4J100 AL08P BA02P BA05P BA15P BA34P BA40P BA41P BA45P BA55P BB01P BB18P BC43P CA01 CA04 CA05 DA61 JA28 JA32

Claims (18)

[Claims] 1. A recording material for a holographic mass storage medium, comprising at least one dye whose spatial arrangement changes during hologram recording and optionally containing at least one shape anisotropic group, A recording material characterized in that two or more holograms can be recorded at one sample position. 2. The absorption behavior changes, in particular the sensitivity to actinic radiation is 1 in each case.
The sensitivity is preferably reduced by 10% to 100%, more preferably by 50% to 100%, most preferably by 90% to 100%, based on the sensitivity before recording the hologram. 2. The recording material according to claim 1, wherein the dye whose spatial arrangement changes in a manner is a dye among the dyes present in at least one kind. 3. The absorption behavior changes, in particular the sensitivity to actinic light, especially when the molecule moves quickly in a direction perpendicular to the direction of polarization of the actinic light so that the longitudinal axis of the molecule is from 10 ° to the direction of polarization of the actinic light. 90 °, preferably 50 ° to 90 °, more preferably 7
Dyes in which at least one dye has at least one dye that changes spatial arrangement in such a way as to decrease in that it will be located at an angle of 5 ° to 90 °, most preferably 85 ° to 90 °. The recording material according to claim 1, wherein the recording material is provided. 4. The light density in the wavelength range from 390 to 800 nm, preferably from 400 to 650 nm, more preferably from 510 to 570 nm, most preferably from 520 to 570 nm, is equal to ≦ 2, preferably equal to 1, or 4. Recording material according to one or more of the preceding claims, characterized in that is less than, in particular equal to or less than 0.3. 5 .gtoreq.0.1 mm, preferably> 0.5 mm, more preferably> 1.
5. A recording material according to claim 1, wherein the recording material has an irradiation thickness of 0 mm, most preferably 5 cm or less. 6. The recording material according to claim 1, wherein the recording material mainly contains a polymer or oligomer organic material. 7. The light density of the recording material is preferably adjusted by the concentration of a dye in at least one type of dye.
The recording material according to one or more of the above. 8. The recording material according to claim 1, wherein the light density is adjusted by the molar extinction coefficient of at least one of the dyes. 9. A polymer or oligomeric amorphous organic material, preferably a side-chain polymer and / or a block copolymer and / or a graft polymer. Recording material. 10. The electromagnetic radiation preferably has a wavelength in the range of 390 to 800.
nm, more preferably 400 to 650 nm, most preferably 510 nm to 570
10. The recording material according to claim 1, wherein the recording material is a laser beam of nm. 11. Use of a recording material according to one or more of claims 1 to 10, wherein at least one, more preferably more than 100, even more preferably one, location of the storage material. Is used for recording a large number of holograms in excess of 500, most preferably in excess of 1000, especially for angle-dependent recording. 12. Use of the recording material according to one or more of claims 1 to 10, for reading a large amount of holograms, in particular for reading angle-dependent. 13. A holographic mass storage medium, comprising:
A holographic mass storage medium comprising the recording material described in Item 0. 14. The recording material comprises any desired form of one or more unsupported objects, preferably an unsupported two-dimensional structure, more preferably an unsupported film, which comprises a multilayer structure. 14. Holographic mass storage medium according to claim 13, characterized in that it is contained within an object, preferably at least one substrate layer. 15. A method for producing a holographic mass storage medium according to at least one of claims 13 and 14, wherein the operation is carried out below 300 ° C., preferably below 220 ° C., according to normal injection molding processes. Comprises a step performed at a temperature of 180 ° C. or lower. 16. A polymer comprising a compound of the formula (I)[Where X¹And X^TwoAre the same or similar, and the same or similar Hammett
Indicating a constant, and R¹And R^TwoRepresents, independently of one another, hydrogen or a non-ionic substituent; and
m and n each independently represent an integer of 0 to 4, preferably an integer of 0 to 2
Then X¹And X^TwoIs preferably each -X¹'-R^ThreeAnd -X^Two'-R^FourRepresents
And X¹'And X^Two'Is a direct bond, -O-, -S-,-(N-R^Five)-, -C (R⁶R ⁷ )-,-(C = O)-,-(CO-O)-,-(CO-NR^Five)-,-(SO_Two
)-,-(SO_Two-O)-,-(SO_Two-NR^Five)-,-(C = NR⁸)-Or-
(CNR⁸-NR^Five)-, R^Three, R^Four, R^FiveAnd R⁸Are, independently of one another, hydrogen, C₁To C₂₀-Alkyl,
C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C₂₀-Alkenyl, C₆To C_Ten-Ant
, C₁To C₂₀-Alkyl- (C = O)-, C_ThreeTo C_Ten-Cycloalkyl-
(C = O)-, C_TwoTo C₂₀-Alkenyl- (C = O)-, C₆To C_Ten-Ally
Ru- (C = O)-, C₁To C₂₀-Alkyl- (SO_Two)-, C_ThreeTo C_Ten-Shiku
Low alkyl- (SO_Two)-, C_TwoTo C₂₀-Alkenyl- (SO_Two)-Or C₆Or
La C_Ten-Aryl- (SO_Two)-, Or X¹'-R^ThreeAnd X^Two'-R^FourIs hydrogen, halogen, cyano, nitro, CF_ThreeOr
CCl_ThreeMay be represented by R⁶And R⁷Are, independently of one another, hydrogen, halogen, C₁To C₂₀-Alkyl,
C₁To C₂₀-Alkoxy, C_ThreeTo C_Ten-Cycloalkyl, C_TwoTo C₂₀-Al
Kenyl or C₆To C_Ten-Represents an aryl] is a polymer chemically bonded thereto. 17. A compound of the formula (II) 17. A polymer as claimed in claim 16, comprising at least one monomer of the formula wherein R represents hydrogen or methyl and the other groups are as defined above. . 18. The recording material according to claim 1, wherein said recording material is a recording material.
And a process for producing a polymer according to paragraph 1 wherein the monomer among the at least one monomer present is polymerized without further solvent, this polymerization being preferably a free radical polymerization, more preferably Is a process characterized by initiating the polymerization with a free radical initiator and / or UV light and / or heat.