JP2696696B2 - Information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an information recording medium having a recording layer containing a polymer liquid crystal. [Related Art] In recent years, rewritable recording media for applications such as large-capacity memories and displays have been actively developed. As one of them, a device utilizing phase transition of liquid crystal is known. For example, a pair of transparent electrodes or a liquid crystal layer that is maintained in an orientation sandwiched by a suitable substrate is optically transparent. Therefore, raise the temperature of this liquid crystal layer,
The liquid crystal layer does not return to its original transparent state but shows a light scattering state when the temperature is raised to a phase transition temperature (nematic phase → liquid phase or smectic phase → nematic phase) or higher and rapidly cooled. That is,
Recording and reading are performed based on this contrast difference. Further, after writing, by applying an electric field between the electrodes of the recording medium or by heating / cooling, the transition to the original smectic phase or the like is performed and the data can be erased. In addition, heating can be performed while applying a voltage, or erasing can be performed by heating without applying a voltage. Recently, polymer liquid crystals having a glass transition point and excellent memory properties have been attracting attention. Usually, a small and inexpensive semiconductor laser is often used to heat the polymer liquid crystal layer, but the oscillation wavelength of this laser is usually 650 nm or more, and in general, such as argon laser, helium-neon laser, etc. Laser light power is smaller than gas laser. Since ordinary liquid crystals have no absorption in such a near-infrared region, it is known that a liquid crystal contains a light-absorbing dye. However, dyes having absorption in the near-infrared region are generally not sufficiently thermally stable in liquid crystal, and have a problem in that, when writing and erasing are repeated, a part of the dye is decomposed and a sufficient contrast cannot be obtained. [Problems to be Solved by the Invention] The present invention has been made in order to solve the above-mentioned problems of the prior art, and has an absorption characteristic at a wavelength in a near-infrared region and dissolves in a liquid crystal. Stable in a dispersed state,
An object of the present invention is to provide an information recording medium in which recording characteristics are not deteriorated even when writing and erasing are repeated. [Means for Solving the Problems] and [Action] The object of the present invention has been achieved by including at least one of the following metal chelate compounds in a polymer liquid crystal as a result of the study by the present inventors. It turned out to be. That is, the present invention relates to an information recording medium having a recording layer containing a polymer liquid crystal, wherein the recording layer is selected from the group consisting of compounds represented by the following general formulas [1] to [6]. An information recording medium comprising at least one metal chelate compound dissolved or dispersed therein. Further, the present invention relates to an information recording medium having a recording layer containing a polymer liquid crystal having a chiral asymmetric carbon, wherein the metal chelate compound is dissolved or dispersed in the recording layer. It is a recording medium. Examples of the metal chelate compound used in the present invention are represented by the following general formulas [1] to [7]. General formula [1] (Wherein, R ₁₅ is a hydrogen atom, a hydroxyl group, an alkyl group, may be combined with other R ₁₅ with an aryl group .R ₁₆
Represents an alkyl group, a halogen atom, a hydrogen atom, a nitro group or a benzo-condensed group, and the central metal M is Cu, Ni, Co or Pd.
Represents ) General formula [2] (In the formula, R ₁₇ may be a hydrogen atom, a hydroxyl group, an alkyl group, or an aryl group and may be bonded to another R _17. R ₁₈ is a hydrogen atom, a halogen atom, an alkyl group, a nitro group, or a benzo-condensed group. And M represents Cu, Ni, Co or Pd.) General formula [3] (In the formula, R ₁₉ represents an alkyl group, an aryl group, R ₂₀ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a nitro group or a benzo-condensed group, and M represents Cu, Ni or Pd.) Equation [4] (In the formula, R ₂₁ represents an alkyl group, an aryl group, R ₂₂ represents a hydrogen atom, a halogen atom, an alkyl group or a benzo-condensed group, and M represents Cu, Ni, or Pd.) General formula [5] (In the formula, R ₂₃ represents a hydrogen atom, a halogen atom or an alkyl group, and M represents Cu or Ni.) General formula [6] (Wherein, R ₂₄ represents a hydrogen atom or an alkyl group;
Represents Cu, Ni, Co or Mn. ) General formula [7] (Wherein R ₂₅ and R ₂₆ are a substituted or unsubstituted alkyl group,
An acyl ring, an aryl group, or an aromatic ring may be formed by R ₂₅ and R ₂₆ . M represents Cu, Ni, Co or Pd. In this case, M has a charge and may have a counter ion. Next, specific examples of the metal chelate compounds represented by the general formulas [1] to [7] are shown in Table 1 below, but the present invention is not limited thereto. The metal chelate compound has absorption in the near infrared region, is useful as a stable light-absorbing dye, and has good compatibility or dispersibility with a polymer liquid crystal. Some of them have dichroism, and if these dichroic compounds are dissolved in a polymer liquid crystal, a thermally stable host-guest type memory and display medium can be obtained. The polymer liquid crystal may contain two or more metal chelate compounds. Further, the metal chelate compound may be combined with another near-infrared absorbing dye or dichroic dye. Representative examples of near-infrared absorbing dyes suitably combined include cyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine, anthraquinone, triphenodithiazine,
Dyes such as xanthene, triphenylmethane, pyrylium, croconium, azulene and triphenylamine. The amount of the metal chelate compound added to the liquid crystal is about 0.01% to 5% by weight, preferably 0.05% to 1%. The liquid crystal used in the present invention is a polymer thermotropic liquid crystal, and utilizes a nematic, smectic, chiral smectic, or cholesteric phase as an intermediate phase. The primary basic structures of the polymer thermotropic liquid crystal that can be used in the present invention are classified into the following two. Mesogen groups or relatively rigid and long atomic groups connected by flexible chains. Those having a mesogen group or a relatively rigid and long atomic group in the side chain. Further, a ferroelectric polymer liquid crystal having a chiral asymmetric carbon can also be used, and it has been confirmed that the compound shown in the present invention and the metal chelate compound have good compatibility or dispersibility. Table 2 shows specific examples of these polymer thermotropic liquid crystals. In the present invention, the polymer liquid crystal can be used as a mixture with several different kinds of polymer liquid crystals. It is also possible to use a mixture of a high-molecular liquid crystal and a low-molecular liquid crystal.
Preferably it is 10 or less. The low-molecular liquid crystal is not particularly limited, and ordinary low-molecular liquid crystals can be used. If necessary, ordinary polymers (for example, olefin resin, acrylic resin, polystyrene resin, polyester resin, polyurethane resin, polycarbonate resin, etc.), oligomers, various antioxidants, etc.
Various plasticizers, various ultraviolet absorbers, quencher and the like may be contained. Polymer liquid crystal thinning can be achieved by dissolving the polymer liquid crystal in a solvent, coating it on a substrate by spin coating, dipping, etc., and then drying it. Alternatively, a film may be used in advance and used. Note that the thickness of the liquid crystal layer is preferably about 0.01 to 100 μm. Further, in order to uniformly align the polymer liquid crystal in a certain direction, an alignment method generally known can be used. For example, as the orientation method, a rubbing method, an oblique deposition method, a method of applying shear stress between two substrates, a method of slowly performing a phase transition while applying a magnetic field, and a method of aligning with a spacer edge can be used. FIGS. 1 and 2 are sectional views showing an embodiment of the information recording medium of the present invention. In FIG. 1, reference numeral 1 denotes a substrate, 2 denotes an alignment film, 3 denotes a recording layer of the present invention, and 4 denotes a reflective layer. In FIG. 2, reference numerals 1, 2 and 3 are the same as those in FIG. Reference numeral 5 indicates a transparent electrode, and reference numeral 6 indicates an electrode / reflection layer. FIG. 3 is a schematic view of an apparatus for writing and reading by irradiating a recording medium with laser. In FIG. 3, writing is performed by focusing a laser beam emitted from a semiconductor laser 8 as a laser oscillator by an optical system 11 on a recording medium.
It is incident on 10. Reading is performed by irradiating a laser beam emitted from a semiconductor laser 8 which is a laser oscillator to a recording medium 10 through an optical system 11 and a beam splitter 7, and using the reflected light to read again by a photodetector 9 through a beam splitter 7. Do. [Operation] The information recording medium of the present invention contains a metal chelate compound in a recording layer containing a polymer liquid crystal. The reason why the metal chelate compound is stable in the polymer liquid crystal is not clear, It is presumed that a high molecular weight and a low extinction coefficient are stable in a polymer liquid crystal and exhibit a light absorbing ability. EXAMPLES Hereinafter, the present invention will be described in more detail based on examples. Example 1 A polyamic acid solution (manufactured by Hitachi Chemical Co., Ltd., PIQ) was applied to a disk-shaped glass substrate having a diameter of 130 mm and a thickness of 1.2 mm. After heating, a rubbing treatment was performed to provide a polyimide alignment film. A side chain type polymer liquid crystal and a metal chelate compound (compound No. 3 in Table 1) shown below were mixed with 1,1,2-trichloroethane, applied by a spinner method, and dried to a thickness of 3 μm.
Was formed. The addition amount of the metal chelate compound is 0.15 wt% with respect to the liquid crystal. Further, a substrate having a polyimide alignment film provided in the same manner as described above on a glass substrate having a reflective film (aluminum vapor-deposited film) formed on the polymer liquid crystal layer via a spacer (thickness of 3 μm) on the outer periphery. I combined. FIG. 1 shows a part of the cross-sectional configuration. The above-described laminate was heated to 90 ° C. and gradually cooled to bring the liquid crystal layer into a nematic layer state, thereby producing an information recording medium. As shown in FIG. 3, when the recording medium was irradiated from the transparent substrate side with a recording power of 3.0 mW by a semiconductor laser 8 of 830 nm as shown in FIG. 3, the orientation of the irradiated part was disturbed, and the recording medium was scattered. Next, reproduction was performed with a read power of 0.3 mW, the reproduction light was measured by the photodetector 9, and its contrast ratio was measured. A → signal intensity of unrecorded portion, B → signal intensity of recorded portion) were calculated. Further, the substrate on which the recording was performed was heated to 90 ° C. and gradually cooled, and erasing was performed according to the orientation of the recording portion. Further, recording and erasing were repeated, and at the time of repeating 300 times, reproduction was performed and the contrast ratio was measured. Examples 2 to 10 Information recording media were produced in the same manner as in Example 1 except that the metal chelate compounds to be mixed into the polymer liquid crystal were those shown in Table 3 below. The contrast ratio was measured in the same manner. Comparative Example 1 An information recording medium was produced in the same manner as in Example 1 except that the following dyes were mixed in the polymer liquid crystal. However, the dye content is 0.
1 wt%. Example 11 130 mm in diameter and 1.2 m thick in which ITO was deposited as a transparent electrode layer
A polyamic acid solution (PIQ manufactured by Hitachi Chemical Co., Ltd.) was applied onto a glass substrate having a thickness of m, heated, and rubbed to form a polyimide alignment film. A ferroelectric polymer liquid crystal and a metal chelate compound (compound No. 3 in Table 1) shown below are dissolved in 1,1,2-trichloroethane, applied by a spinner method, dried and dried to form a liquid crystal layer having a thickness of 3 μm. Was formed. In the same manner as in Example 1, a substrate provided with a polyimide alignment film was superposed on a glass substrate on which an electrode layer and a reflective layer (aluminum vapor-deposited film) had been formed via a spacer in the same manner as described above. FIG. 2 shows a part of the sectional configuration. The above-mentioned laminated body is heated to 90 ° C., and then gradually cooled, so that the liquid crystal layer is in a uniaxially oriented smectic phase state, a voltage is applied between the electrodes, the polarization direction is aligned in a certain direction, and information is recorded. A medium was prepared. The recording medium is heated by irradiating the recording section from the transparent electrode side with a recording power of 3.0 mW with a 830 nm semiconductor laser while applying a reverse electric field between the transparent electrode (ITO) and the AI electrode in this recording medium, thereby causing the spontaneous polarization. Recording was performed by reversing the direction. Next, without applying an electric field, a laser beam is irradiated through a polarizer at a reproduction output of 0.3 mW, and the reflected light includes a difference in birefringence due to a difference in polarization direction. Was measured and the contrast ratio was calculated. Further, while applying a forward electric field again between the ITO-Al electrodes, irradiation was performed with a laser power of 3.5 mW to erase the recorded portion or the entire surface. When recording and erasing were repeated 300 times again, reproduction was performed and the contrast ratio was measured. Examples 12 to 18 Information recording media were produced in the same manner as in Example 11 except that the metal chelate compounds to be mixed in the ferroelectric polymer liquid crystal were those shown in Table 4 below. Comparative Example 2 An information recording medium was produced in exactly the same manner as in Example 11, except that the dye used in Comparative Example 1 was used as the organic dye. Table 5 summarizes the results of the measurement of the contrast ratio of the above Examples and Comparative Examples. [Effects of the Invention] According to the information recording medium of the present invention configured as described above, an excellent effect that is thermally stable and does not lower the contrast ratio of recording even when recording / erasing is repeated is provided. can get.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an information recording medium according to the present invention, and FIG.
The figure shows a schematic diagram of an optical system for recording, reproducing, and erasing. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Alignment film 3 ... Recording layer 4 ... Reflection layer 5 ... Transparent electrode 6 ... Electrode / reflection layer 7 ... Beam splitter 8 ... Semiconductor laser 9 ... Light detection Device 10: Recording medium, 11: Optical system 12, Reflecting mirror, 13: Polarizer

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location G11B 7/24 516 B41M 5/26 102 (72) Inventor Kazuo Yoshinaga 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 Canon Inc. (56) References JP-A-60-165293 (JP, A) JP-A-60-165294 (JP, A) JP-A-60-166487 (JP, A) JP-A-60-165 -168691 (JP, A) JP-A-62-157341 (JP, A)

Claims (1)

(57) [Claims] An information recording medium having a recording layer containing a polymer liquid crystal, wherein the recording layer has the following general formulas [1] to [6]
An information recording medium characterized in that at least one metal chelate compound selected from the group consisting of compounds represented by the formula is dissolved or dispersed. General formula [1] (Wherein, R ₁₅ is a hydrogen atom, a hydroxyl group, an alkyl group, may be combined with other R ₁₅ with an aryl group .R ₁₆
Represents an alkyl group, a halogen atom, a hydrogen atom, a nitro group or a benzo-condensed group, and the central metal M is Cu, Ni, Co or Pd.
Represents ) General formula [2] (In the formula, R ₁₇ may be a hydrogen atom, a hydroxyl group, an alkyl group, or an aryl group and may be bonded to another R _17. R ₁₈ is a hydrogen atom, a halogen atom, an alkyl group, a nitro group, or a benzo-condensed group. And M represents Cu, Ni, Co or Pd.) General formula [3] (In the formula, R ₁₉ represents an alkyl group, an aryl group, R ₂₀ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a nitro group or a benzo-condensed group, and M represents Cu, Ni or Pd.) Equation [4] (In the formula, R ₂₁ represents an alkyl group, an aryl group, R ₂₂ represents a hydrogen atom, a halogen atom, an alkyl group or a benzo-condensed group, and M represents Cu, Ni, or Pd.) General formula [5] (In the formula, R ₂₃ represents a hydrogen atom, a halogen atom or an alkyl group, and M represents Cu or Ni.) General formula [6] (Wherein, R ₂₄ represents a hydrogen atom or an alkyl group;
Represents Cu, Ni, Co or Mn. ) 2. An information recording medium having a recording layer containing a polymer liquid crystal having chiral asymmetric carbon, wherein a metal chelate compound is dissolved or dispersed in the recording layer. 3. 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [1]. General formula [1] (Wherein, R ₁₅ is a hydrogen atom, a hydroxyl group, an alkyl group, may be combined with other R ₁₅ with an aryl group .R ₁₆
Represents an alkyl group, a halogen atom, a hydrogen atom, a nitro group or a benzo-condensed group, and the central metal M is Cu, Ni, Co or Pd.
Represents ) 4. 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [2]. General formula [2] (In the formula, R ₁₇ may be a hydrogen atom, a hydroxyl group, an alkyl group, or an aryl group and may be bonded to another R _17. R ₁₈ is a hydrogen atom, a halogen atom, an alkyl group, a nitro group, or a benzo-condensed group. And M represents Cu, Ni, Co or Pd.) 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [3]. General formula [3] (In the formula, R ₁₉ represents an alkyl group, an aryl group, R ₂₀ represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a nitro group or a benzo-condensed group, and M represents Cu, Ni or Pd.) . 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [4]. General formula [4] (In the formula, R ₂₁ represents an alkyl group, an aryl group, R ₂₂ represents a hydrogen atom, a halogen atom, an alkyl group or a benzo-condensed group, and M represents Cu, Ni, or Pd.) 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [5]. General formula [5] (In the formula, R ₂₃ represents a hydrogen atom, a halogen atom or an alkyl group, and M represents Cu or Ni.) 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [6]. General formula [6] (Wherein, R ₂₄ represents a hydrogen atom or an alkyl group;
Represents Cu, Ni, Co or Mn. ) 9. 3. The information recording medium according to claim 2, wherein the metal chelate compound is a compound represented by the following general formula [7]. General formula [7] (Wherein R ₂₅ and R ₂₆ are a substituted or unsubstituted alkyl group,
An acyl ring, an aryl group, or an aromatic ring may be formed by R ₂₅ and R ₂₆ . M represents Cu, Ni, Co or Pd. In this case, M has a charge and may have a counter ion. ) 10. 3. The information recording medium according to claim 2, wherein the polymer liquid crystal is a ferroelectric polymer liquid crystal.