JP2887068B2 - Optical element and optical recording element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel optical element using a composition comprising a polymer liquid crystal, and more particularly to an optical recording element capable of repeatedly performing recording / erasing.

[0002]

2. Description of the Related Art Polymer liquid crystals are novel functional materials.
Application to recording materials and display materials is being studied. For example, recording materials are disclosed in JP-A-59-10930 and JP-A-63-22066, and display materials are disclosed in JP-A-62-14114 and JP-A-Hei.
No. 2513, and Polym. Commun.
Vol. 24, 364 (1983), Japan Di
spray, 290 (1986) and the like. In addition, the technology for crosslinking polymer liquid crystals is disclosed in Makro.
mol. Chem. Rapid Commun. , Vo
l. 2,317 (1981), Makromol. Ch
em. , Vol. 188, 665 (1987), Pol
ymer, Vol. 28, 639 (1987) , Mak
romol. Chem. , Vol. 187, 1915
( 1986 ), and is expected to be applied as an elastomer, a novel light modulation element or a display element. In addition, regarding technology related to display elements that reduce damage due to the thermal head by crosslinking main-chain type polymer liquid crystals,
It is disclosed in JP-A-2-42415.

[0003]

In an optical element and a medium using a polymer liquid crystal of the prior art, in particular, in a structure in which recording / display and erasing are performed by using heat, unevenness in temperature and cooling rate is not uniform. For example, the reproducibility of the optical characteristics was poor. In particular, in an optical element that performs display or recording using light scattering, since the light scattering property (whiteness) greatly depends on the cooling rate after heating, precise light scattering property is required to obtain uniform light scattering property. There is a problem that the cooling rate needs to be controlled, and when the area is increased, the light scattering becomes uneven. Further, the recording speed or the erasing speed is slow, and it takes a long time for recording or erasing. When a thermal head is used, there is a problem that one of recording and erasing cannot be performed at high speed. Therefore, the present invention has been made to solve the above-mentioned problems in the conventional technology. That is, the object of the present invention is to record /
It is an object of the present invention to provide an optical element having improved erasing reproducibility, speed, and optical characteristics. Another object of the present invention is to provide an optical recording element using the above optical element.

[0004]

An optical element according to the present invention comprises a side chain type polymer liquid crystal composition having a multi-domain structure having optical anisotropy, wherein the side chain type polymer liquid crystal is provided. composition, characterized in that it is obtained by forming by crosslinking while holding the multi-domain structure a side chain type polymer liquid crystal. Optical recording element utilizing the optical element of the present invention comprises a substrate, which is formed by crosslinking while holding the multi-domain structure a side chain type polymer liquid crystal, a multi-domain structure having optical anisotropy A polymer liquid crystal composition layer (hereinafter, referred to as a polymer liquid crystal layer) and a protective layer.

[0005] The "multi-domain structure having optical anisotropy" herein is composed of a plurality of domains having optical anisotropy such as birefringence formed by a composition containing a side chain type polymer liquid crystal. Means structure. Such domains are formed by the difference in the orientation of liquid crystal molecules inside the polymer liquid crystal composition. In other words, the liquid crystal molecules are aligned in substantially the same direction inside one domain, and as a result of the alignment, one domain has optical anisotropy and can be optically distinguished from other domains. . The “multi-domain structure” is an aggregate of domains exhibiting such optical anisotropy, and the direction of optical anisotropy (the orientation direction of liquid crystal molecules) for each domain is preferably random.

First, the side chain type polymer liquid crystal used in the present invention will be described. As the polymer liquid crystal, there are known a main chain type and a side chain type polymer liquid crystal in which a mesogen (a molecule exhibiting liquid crystallinity) is bonded to a main chain or a side chain. In particular side-chain type polymer liquid crystal in the present invention is used. In the present invention, a polymer liquid crystal containing a reactive group as one component of a main chain or a side chain is preferably used. Reactive groups include vinyl groups, acrylate groups, polymerizable groups such as methacrylate groups, heterocyclic groups such as epoxy groups, isocyanate groups, hydroxyl groups, amino groups, acid amide groups, thiol groups, carboxyl groups, sulfonic acid groups, Phosphate groups, metal alcoholate groups,
Reactive groups such as magnesium halide (Grignard) groups can be used as preferred.

Next, a method for producing such a side chain type polymer liquid crystal will be described. Usually, the side-chain type high-dispersion liquid crystal can be produced by polymerizing a polymerizable mesogen compound or adding a mesogen compound capable of undergoing an addition reaction to a reactive polymer such as hydrogenated polysilicone. Such a technique is described in Makromol. Che
m. , P273, 179 (1978), Eur, Pol
ym. J. , P651, 18, (1982) and Mo.
l. Cryst. Liq. Cryst. , P167, 1
69 (1989). Used in the present invention
Side-chain polymer liquid crystal (hereinafter simply referred to as “polymer liquid crystal”)
U. ) Can be produced in a manner similar to that disclosed therein. That is, a polymerizable mesogen compound (mesogen monomer) is copolymerized with a polymerizable compound having a reactive group (reactive monomer), or a polymerizable mesogen compound having a reactive group capable of addition reaction with an addition-reactive mesogen compound. It can be prepared by adding a compound to a reactive polymer. Examples of the polymerizable mesogen compound and the mesogen compound capable of addition reaction that can be used in the present invention include biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, phenylpyrimidine, and diphenyl. Rigid molecules (mesogens) such as acetylene, biphenylbenzoate, cyclohexylbiphenyl, terphenyl, etc., to which acrylate, methacrylate or vinyl groups are bonded via alkyl spacers of a predetermined length Compounds and the like are typical examples.

[0008] Representative structural examples of these compounds are shown below. _{CH 2 = C (R) -COO-} (CH 2) k -O-A CH 2 = CH- (CH 2) in _k -O-A [wherein, R represents a hydrogen atom or a methyl group, k is 1 ~
An integer selected from 30 is shown, and A represents a mesogen having the following structure.

Embedded image (Wherein X and Y are each a single bond, -N = N-,
-N (→ O) = N-, -CH = N-, -N = CH-,-
COO -, - O (C = O) - and represents a group selected from an ethynylene group, p is an integer selected from 1 to 5, R ¹ represents an alkoxy group, a halogen atom, a cyano group, a carboxyl group, Represents a group selected from alkyl groups, p
Is 2 or more, each R ¹ may be different. )] These mesogenic compounds in the present invention may further contain a reactive group other than a double bond.

The polymer liquid crystal used in the present invention includes, specifically, a compound having a reactive group (reactive monomer) to be copolymerized with the mesogen compound, specifically, (meth) acrylic acid, ω-carboxy-poly Caprolactone-mono (meth) acrylate, vinyl sulfonate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth)
Acrylate, 2- (meth) acryloxyethyl acid phosphate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloxyethyl succinate, phthalic acid mono (meth) acrylate, 2- (meth) ) Acryloxyethyl (2-hydroxyethyl) phthalate, 4- (meth) acryloxyalkyloxy-benzoic acid, glyceryl (meth) acrylate, hydroxy-substituted styrene, meth (acryl) amide, N, N-dimethylaminoethyl (Meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, 2-propen-1-ol, 5-hexen-1-ol and the like. After copolymerization or addition of these compounds, another reactive group may be introduced to convert the reactive group. For example, a polymerizable group can be introduced into a polymer side chain by adding (meth) acrylic acid or the like to a hydroxyl group introduced by copolymerizing hydroxyethyl (meth) acrylate. Furthermore, it is also possible to use various mesogen compounds capable of polymerization or addition having the above-mentioned reactive group. For example, in the structure example of the above-mentioned mesogen compound, a hydroxyl group, compounds having a carboxyl group or an amino group can be used as the substituent R ^1. What is illustrated here is an example, and there is no particular limitation. The copolymerization ratio or co-addition amount of the compound having a reactive group in the polymer liquid crystal is preferably in the range of 0.1 mol% to 70 mol% as a monomer unit.
The molecular weight of the polymer liquid crystal is 1000 to 1 in terms of weight average molecular weight.
The range is 100,000, particularly preferably 10,000 to 500,000.

[0010]

The optical element of the present invention contains a polymer liquid crystal composition having an optically anisotropic multi-domain structure formed by crosslinking side chain type polymer liquid crystals as described above. The direction of the optical anisotropy (the alignment direction of the liquid crystal molecules) for each domain in the domain structure is preferably random. Also, when the size of the domain diameter in the multi-domain structure is about the wavelength of visible light, the visible light is strongly scattered and becomes strongly clouded. Therefore, in the present invention, a specific preferable domain diameter is that the domain diameter at the maximum of the domain distribution number is 3
μm or less, and preferably in the range of 0.2 μm to 1.5 μm. Further, it is preferable that the difference between the maximum domain diameter and the minimum domain diameter in the domain diameter distribution is a uniform domain having a size of about 5 μm or less. The size of such a domain diameter can be controlled by changing the composition of the polymer liquid crystal or the composition of the polymer liquid crystal composition.

A multi-domain structure having the above characteristics is
It is prepared by a method in which a specific multi-domain structure is formed in advance and cross-linking is performed while maintaining the multi-domain structure. Next, a method for manufacturing the optical element of the present invention will be specifically described. At least cross-linking of the polymer liquid crystal is,
Preferably, a catalyst or a polyfunctional reactive compound is added to the polymer liquid crystal prepared by the above-described method, and heat,
It can be performed by applying light, an electron beam, or the like. As the catalyst, various ultraviolet polymerization initiators, thermal polymerization initiators, etc., as the polyfunctional reactive compound, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional aldehyde compound, a polyfunctional amine compound, Polyfunctional carboxyl compounds and the like are preferably used. For specific examples of the catalyst and the polyfunctional reactive compound, for example, as the catalyst, an azo-based polymerization initiator such as azobisisobutyronitrile (ABIN), a peroxide-based polymerization initiator such as benzoyl peroxide, Examples include a phenylketone-based ultraviolet polymerization initiator and the like. Examples of the polyfunctional reactive compound include toluene diisocyanate (TDI),
4'-diphenylmethane diisocyanate, 3,4-dichlorophenyl diisocyanate, polymethylene polyphenyl isocyanate, hexamethylene diisocyanate (HDI), adduct of TDI or HDI with a polyol such as trimethylolpropane, bisphenol A
Examples thereof include diglycidyl, melamine, ethylenediamine, hexamethylenediamine, phenylenediamine, glutaraldehyde, terephthalaldehyde, oxalic acid, succinic acid, glutaric acid, maleic acid, terephthalic acid, pyromellitic acid, and pyromellitic anhydride. The addition amount of the catalyst or the polyfunctional reactive compound is preferably in the range of 0.01% by weight to 20% by weight based on the polymer liquid crystal.

Various components other than those described above may be added to the polymer liquid crystal composition of the present invention for the purpose of improving the properties. For example, various antioxidants such as hindered amine and hindered phenol may be added for the purpose of improving weather resistance, and for the purpose of improving display contrast, anthraquinone-based, styryl-based, azomethine-based and azo-based ones may be added. And other various dichroic dyes. Various fluorescent dyes may be added for the purpose of improving light scattering. Furthermore, in order to efficiently perform thermal writing by laser light, various laser light absorbing dyes (78
When a general semiconductor laser having a wavelength of 0 to 830 nm is used, it is also preferable to add a near-infrared absorbing dye such as phthalocyanine, squarylium, or azurenium. The amounts of the various components listed above are preferably in the range of 0.01 to 5% by weight in the polymer liquid crystal composition. Further, a low molecular weight liquid crystal compound may be added to the polymer liquid crystal composition in a range of 1 to 20% by weight.

The above polymer liquid crystal composition is preferably processed into a desired form in the form of a heated mixture or a solution to which a solvent is added, and then the polymer liquid crystal is crosslinked. What has been crosslinked in this way has a self-holding property as it is, in the form of a film, a block, a fiber, etc.,
Although it can be used as an optical element, it is preferably used as an optical element in a form formed on a substrate or laminated between two substrates. Various polymer films such as polyethylene terephthalate (PET), polyvinyl chloride, polypropylene, and polyimide, paper, metal,
Ceramic and glass can be used. In particular, when used as a transmissive display element, it is preferable to use a transparent substrate. It is also preferable to use a substrate with electrodes as the substrate. A preferable application example using the optical element of the present invention is a reversible optical recording element capable of recording and erasing. Hereinafter, the optical recording element of the present invention will be described.

FIG. 1 shows a configuration example of the optical recording element of the present invention. FIG. 1A shows a basic structure in which a polymer liquid crystal layer (recording layer) 2 is laminated on a base material 1 and a protective layer 3 is provided for the purpose of improving surface strength and heat resistance. It has a layer configuration. FIG. 1B has a layer configuration in which a colored layer 4 is provided on the back surface of the base material l, and FIG.
Has a layer configuration in which the light reflection layer 5 is provided between the base material 1 and the polymer liquid crystal layer 2.

The polymer liquid crystal layer and the protective layer can be formed by a commonly used method such as a coating method using a solvent or a hot melt coating method. In the above-mentioned optical recording element, the thickness of the recording layer is not particularly limited, but varies variously depending on the intended contrast. Preferably 1
From 100 to 100 μm, particularly preferably from 5 to 50 μm
Is selected from the range. Further, the protective layer desirably has high heat resistance, and a fluorine polymer, a silicone polymer, a thermosetting polymer, an ultraviolet curable polymer, an electron beam curable polymer, or the like can be used. The protective layer may be laminated in a plurality of layers, and the thickness of the protective layer is preferably 0.
It is selected from the range of 1 to 20 μm. The same substrate as described above is used as the substrate.

In the present invention, as shown in FIGS. 1B and 1C, it is preferable to provide a light reflecting layer, a light absorbing layer and a colored layer for the purpose of improving the contrast. As the light reflection layer, a metal film such as aluminum or silver,
As the light absorbing layer or the colored layer, a polymer film containing a dye can be generally used. Its thickness is preferably 0.0
It is selected from the range of 01 to 100 μm.

Next, a recording / erasing method using thermal control for the optical recording element will be described. Recording / erasing can also be performed by an electric field or a magnetic field. The prepared recording layer exhibits a light scattering (white turbidity) state derived from the multi-domain structure. In this state, the polymer liquid crystal is made isotropic by partial heating using a thermal head or laser light, etc., and the heated part is fixed in the isotropic state by quenching below the glass transition point. Be transparent. On the other hand, in the case of erasing, after the heating, cooling is performed more slowly than in recording, so that an initial light scattering state is obtained, and the erasing is completed. That is, recording / erasing can be performed reversibly and repeatedly. As a recording / erasing heating means, for example, a thermal head is used, and recording and erasing can be performed by controlling a pulse width and energy applied to the thermal head.

[0019]

[Action] optical element of the present invention, high has a multi-domain structure having optical anisotropy formed by crosslinking while holding the Ma <br/> Ruchi domain structure of polymer liquid crystal side chain type It is characterized by containing a molecular liquid crystal composition, and has an effect of stabilizing a specific multi-domain structure (microstructure) by cross-linking and making it a memory. Therefore, the optical element of the present invention can be used as an excellent optical recording medium, display medium, light modulation element or reversible thermosensitive recording medium. When a polymer liquid crystal is used as a light scattering type optical element, the size of light scattering depends on the domain diameter and density in a multi-domain structure. Was changed from the initial state or partially non-uniform due to heat unevenness, resulting in poor optical characteristics and uneven optical density, resulting in low reproducibility. However, in the optical element of the present invention, the multi-domain structure (microstructure) is thermodynamically stabilized, and the initial domain diameter and density are stored in memory. There is reproducibility in the size and density of the domain diameter in the multi-domain structure. Further, in the case of forming an optically anisotropic multi-domain structure by cooling from a heated optically isotropic state, it is possible to realize an improvement in the formation speed. Therefore, when the optical element of the present invention is applied as a recording / display element, it is necessary to exhibit excellent recording / display / erasing stable reproducibility and to achieve high optical characteristics and high recording / display / erasing speed. Becomes possible.

[0020]

【Example】

(Evaluation method) A thermal printer (8d
ots / mm, up to 0.3 mJ / dot) (recording part is transparent) and hot stamping (1
(30 ° C.). The reflection optical density before / after recording and after recording / erasing was repeated 100 times was measured using X-rite968 (manufactured by X-rite), and the reproducibility was evaluated repeatedly. In the sample in which each polymer liquid crystal layer was formed on a transparent base material, the domain diameter of the multi-domain structure after recording / erasing was repeated 100 times was measured using a laser diffraction particle size distribution analyzer LA manufactured by HORIBA.
The measurement was performed at −700, and the domain diameter at the maximum of the domain distribution and the number of domain distributions was measured.

Example 1 1.9 g of 4-acryloxyhexyloxy-4'-cyano-biphenyl as a mesogenic monomer and 0.1 g of 2-hydroxyethyl acrylate as a reactive monomer were added to azobisisobutyronitrile (ABIN). )
Was polymerized using tetrahydrofuran as a solvent and precipitated and purified three times using ethyl alcohol to obtain 1.9 g of a polymer liquid crystal represented by the following structural formula (I).

Embedded image (Weight average molecular weight (polystyrene conversion by GPC):
40000, Tg (glass transition point): 40 ° C., Ti (liquid crystal phase-isotropic phase transition point): 110 ° C.) Coronate HX (Nippon Polyurethane), a polyfunctional isocyanate compound as a crosslinking agent, was added to 1.0 g of the polymer liquid crystal. A solution obtained by adding 0.05 g of methyl ethyl ketone (MEK) as a solvent to a solution having a thickness of 100 μm was added.
The resultant was coated on a PET film having a thickness of m by using a blade coater and dried to form a polymer liquid crystal layer having a thickness of about 6 μm. The polymer liquid crystal layer after coating and drying scattered light and became cloudy. The Ti (liquid crystal phase-isotropic phase transition point) of the composition before crosslinking was about 90 ° C. Next, at 60 ° C
In an oven for 24 hours to effect crosslinking. The polymer liquid crystal layer after cross-linking was also cloudy as before. Further, an ultraviolet-curable composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied as a protective layer, and cured using a high-pressure mercury lamp to form a protective layer having a thickness of about 2 μm on the polymer liquid crystal layer. The optical recording element was formed.

Example 2 A polymer liquid crystal represented by the following structural formula (II) was synthesized by the same method except that the same mesogenic monomer as in Example 1 was used and acrylic acid was used as a reactive monomer.

Embedded image (Weight average molecular weight (polystyrene conversion by GPC):
40000, Tg (glass transition point): 50 ° C., Ti (liquid crystal phase-isotropic phase transition point): 125 ° C.) To 1.0 g of the polymer liquid crystal, 0.1 g of hexamethylene diisocyanate, which is a polyfunctional isocyanate compound, is used as a crosslinking agent. 03 g, methyl ethyl ketone (MEK) as solvent
The solution obtained by adding 3.0 g was coated on a 100-μm-thick aluminum-evaporated PET film using a blade coater, and dried to form a polymer liquid crystal layer having a thickness of about 6 μm. The polymer liquid crystal layer after coating and drying scatters light,
It was cloudy. The Ti point of the composition before crosslinking was about 100 ° C. Next, the reaction was carried out in an oven at 60 ° C. for 24 hours for crosslinking. The polymer liquid crystal layer after cross-linking was also cloudy as before. A protective layer was formed in the same manner as in Example 1 to produce an optical recording element.

Example 3 1.9 g of the same mesogenic monomer as in Example 1 and 0.1 g of glycidyl acrylate as a reactive monomer were polymerized in the same manner as in Example 1 to obtain a polymer liquid crystal represented by the following structural formula (III). Synthesized.

Embedded image (Weight average molecular weight (polystyrene conversion by GPC):
40000, Tg (glass transition point): 36 ° C., Ti (liquid crystal phase-isotropic phase transition point): 95 ° C.) To 1.0 g of the polymer liquid crystal, 0.1 g of hexamethylenediamine, a polyfunctional amine compound, was added as a crosslinking agent. 04 g and a solution obtained by adding 3.0 g of methyl ethyl ketone (MEK) as a solvent to a 100 μm-thick aluminum-evaporated PET.
The film was applied on a film using a blade coater and dried to form a polymer liquid crystal layer having a thickness of about 6 μm. Coating,
The dried polymer liquid crystal layer scattered light and became cloudy. The Ti point of the composition before crosslinking was about 90 ° C. Next, the reaction was carried out in an oven at 60 ° C. for 24 hours for crosslinking. The polymer liquid crystal layer after cross-linking was also cloudy as before. Further, a protective layer was formed in the same manner as in Example 1,
An optical recording element was manufactured.

Example 4 The polymer liquid crystal synthesized in Example 1 was reacted with acrylic acid chloride in methylene chloride using triethylamine to give the following structural formula (IV) in which an acrylate group was introduced into the side chain. The polymer liquid crystal shown was synthesized.

Embedded image (Weight average molecular weight (polystyrene conversion by GPC):
55000, Tg (glass transition point): 33 ° C., Ti (liquid crystal phase-isotropic phase transition point): 85 ° C.) 1.0 g of this polymer liquid crystal and 0.01 g of an ultraviolet initiator
A solution obtained by adding 3.0 g of methyl ethyl ketone (MEK) as a solvent (Darocure 1173, manufactured by Ciba Geigy) was applied on a 100 μm-thick aluminum-deposited PET film using a blade coater, and dried to obtain a film having a thickness of about 100 μm. A 6 μm polymer liquid crystal layer was formed. The polymer liquid crystal layer after coating and drying scattered light and became cloudy. The Ti point of the composition before crosslinking was about 80 ° C. Ultraviolet rays were irradiated using a high-pressure mercury lamp at a temperature of 25 ° C. to effect crosslinking. The polymer liquid crystal layer after cross-linking was also cloudy as before. Further, a protective layer was formed in the same manner as in Example 1 to produce an optical recording element.

Comparative Example 1 An optical recording element was produced in the same manner as in Example 1 except that no crosslinking agent was added to the polymer liquid crystal (Structural Formula (I)) synthesized in Example 1. The optical recording element after the production was slightly clouded. Comparative Example 2 Only the mesogenic monomer used in Example 1 was homopolymerized to synthesize a polymer liquid crystal having the following structural formula (V).

Embedded image (Weight average molecular weight (polystyrene conversion by GPC):
30,000, Tg (glass transition point): 35 ° C., Ti (liquid crystal phase-isotropic phase transition point): 120 ° C.) Using this high-molecular liquid crystal, optical recording was performed in the same manner as in Comparative Example 1 without adding a crosslinking agent. An element was manufactured. The optical recording element after production was cloudy.

(Evaluation Results) Table 1 shows the evaluation results of the reproducibility of recording / erasing.

[Table 1]

As is clear from the results in Table 1, Example 1
In Nos. To 4, before recording, after erasing for the first time and after repeating 100 times, there was no change in the turbidity (reflection optical density) in the light scattering state, and it was confirmed that excellent whiteness reproducibility was obtained. . On the other hand, in Comparative Examples 1 and 2, not only the white turbidity was low in the initial state, but also the first recording,
The erasure drastically reduced the turbidity to make it transparent, and the reproducibility was significantly deteriorated. In the samples of Examples 1 to 4 after repeating 100 times, the domain diameter at the distribution maximum of the number of domains was 400 nm to 700 nm, and the domain diameter was distributed within the range of 50 nm to 1400 nm.
On the other hand, in the samples of Comparative Examples 1 and 2 after repeating 100 times, the domain diameter at the distribution maximum of the number of domains is 2.5 μm and 2.0 μm, and the domain diameter is 700 nm to 1 nm.
The distribution was in the range of 1.5 μm. From these facts,
Deterioration of the optical density of Comparative Examples 1 and 2 shown in Table 1 was mainly attributable to the fact that the domain grew and became large, and it was confirmed that the turbidity was thereby reduced. Therefore, it was found that the size of the domain diameter in the multi-domain structure affects the display characteristics (optical characteristics), and that the stability of the multi-domain structure affects the reproducibility in the repeated recording / erasing process. As is clear from the above results, in the optical element of the present invention, the fine multi-domain structure is thermodynamically stabilized by crosslinking, and the display characteristics (optical characteristics) and the reproducibility of recording / erasing are excellent. ing.

[0028]

In the optical element and the optical recording element of the present invention exhibits a high and with a side chain type polymer liquid crystal is crosslinked in a state of holding the multi-domain structure as a multi-domain structure with a stable optically anisotropic By using the molecular liquid crystal composition, optical characteristics and reproducibility of repetition of recording / display / erasing are excellent. Therefore, the optical element and the optical recording element of the present invention are excellent in recording / display / erasing speed, repetition stability and reproducibility, and the optical element is an optical recording medium, a display medium, an optical modulation element and a reversible sensor. It can be used as a thermal recording medium.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical recording element of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Polymer liquid crystal layer, 3 ... Protective layer, 4 ... Coloring layer, 5 ... Light reflection layer.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Morikawa 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (56) References JP-A-4-212928 (JP, A) JP-A-5-281522 ( JP, A) JP-A-5-310851 (JP, A) JP-A-4-188107 (JP, A) JP-A 1-145653 (JP, A) JP-A-5-107524 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) G02F 1/1333

Claims (7)

(57) [Claims] 1. An optical element containing a side chain type polymer liquid crystal composition having a multi-domain structure having optical anisotropy, wherein the side chain type polymer liquid crystal composition is a side chain type polymer liquid. Crystal
Optical element, characterized in that formed by crosslinking while holding the multi-domain structure. 2. The optical element according to claim 1, wherein the domain diameter at the maximum of the number of domain distributions is 3 μm or less in the multi-domain structure. 3. The multi-domain structure has a domain diameter at the maximum of the number of domain distributions of 0.2 μm to 1.5 μm.
The optical element according to claim 1, wherein m is m. 4. The optical element according to claim 1, wherein a difference between a maximum domain diameter and a minimum domain diameter in a multi-domain structure is 5 μm or less. 5. The optical element according to claim 1, wherein the side chain type polymer liquid crystal contains a copolymer containing a reactive group. 6. The optical element according to claim 1, wherein the crosslinking is performed by adding a polyfunctional reactive compound. 7. A substrate, which is formed by crosslinking while holding the multi-domain structure a side chain type polymer liquid crystal, polymeric liquid crystal composition layer having a multi-domain structure having optical anisotropy, and An optical recording element comprising a protective layer.