JP2887084B2 - Optical element manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element having a polymer liquid crystal layer capable of reversibly controlling light scattering by an external action.

[0002]

2. Description of the Related Art In recent years, a reversible display recording element capable of reversibly recording and erasing an image has attracted attention. Recording and erasing are performed by using a heating element such as a thermal head for the reversible display recording element. Thermosensitive reversible display recording materials have been developed. As these heat-sensitive recording materials, those having a polymer liquid crystal as a recording layer (Japanese Patent Application Laid-Open No. 4-218024) and those having a composite film in which a low-molecular organic compound is dispersed in a resin base material as a recording layer (for example, US Pat. Japanese Patent Application Laid-Open No. Sho 54-119377) and those using a leuco dye as a recording layer (JP-A-61-2).
No. 37684) and a polymer film obtained by blending two kinds of polymers as a recording layer (JP-A-60-1808).
No. 87) has been proposed. Among these techniques, a thermosensitive reversible display recording material using a polymer liquid crystal is particularly preferable because of its excellent optical properties and durability.

[0003]

By the way, conventionally, in the production method of forming a recording layer by coating and drying a polymer liquid crystal on a sheet-like base material such as a film, an optical element is conventionally required from the viewpoint of production efficiency. A recording material is applied to the film wound up in a roll form using a continuous coating device, dried, and then the film on which the recording layer is formed is wound up again in a roll form. The heat treatment for cross-linking is performed in a state where the film on which the recording layer is formed is wound into a roll. However, when the polymer liquid crystal layer is heat-treated in the form of a roll, heat treatment at an efficient heat treatment temperature improves the adhesiveness and makes contact with the polymer liquid crystal layer wound in a roll. When the film on which the recording layer is formed is pulled out from the roll in the next step, the polymer liquid crystal layer is peeled off, or the film substrate is broken or cut. Was. Therefore, the present invention has been made in view of the above-mentioned problems in the conventional technology. That is, an object of the present invention is to provide an optical element using a polymer liquid crystal as a heat-sensitive recording layer, by performing heat treatment for crosslinking the polymer liquid crystal under specific conditions, thereby improving optical characteristics, durability and recording / recording. Provided is an efficient method for manufacturing an optical element having improved erasing characteristics.

[0004]

The first method of the present invention for producing an optical element involves crosslinking a polymer liquid crystal under a specific structure, and is formed on a sheet-like substrate. after forming a surface protective layer on the polymer liquid crystal layer, the sheet-like substrate in a state wound into a roll, and performing a heat treatment for crosslinking the polymer liquid crystal layer. Also,
The second method of the production method of the light optical element of the present invention, a polymer liquid crystal layer was formed on a base material sheet, after the first heat treatment for controlling the multi-domain structure of the polymer liquid crystal, polymer A surface protection layer is formed on the liquid crystal layer , and a second heat treatment for crosslinking the polymer liquid crystal layer is performed .
The heat treatment for crosslinking the polymer liquid crystal is preferably performed at a temperature lower than the liquid crystal phase-isotropic phase transition temperature of the polymer liquid crystal.

[0005] The optical element of the present invention comprises at least three of a sheet-like substrate, a recording layer composed of a polymer liquid crystal and a surface protective layer.
It consists of two layers. First, a polymer liquid crystal material constituting a recording layer made of a polymer liquid crystal used in the present invention will be described. Generally, as a polymer liquid crystal, a main chain type liquid crystal having a mesogen group (a molecule exhibiting liquid crystallinity) in a main chain, a side chain type polymer liquid crystal having a mesogen group bonded to a side chain, and the like are known. In the present invention, it is preferable to use a side chain type polymer liquid crystal. In the present invention, as the polymer liquid crystal used for crosslinking, a compound containing a reactive group as one component of a main chain or a side chain is preferably used. In these compounds, the crosslinking can be carried out by utilizing a reactive group and adding a catalyst and a polyfunctional reactive compound as required. Examples of the reactive group include a heterocyclic group such as a vinyl group, an acrylate group, a methacrylate group, and an epoxy group and a polymerizable group such as an isocyanate group, a hydroxyl group, an amino group, an acid amide group, a thiol group, and a carboxyl group. Sulfonic acid group, phosphoric acid group, metal alcoholate group, magnesium halide group (Grignard reagent) and the like.

Next, a method for producing a polymer liquid crystal will be described. The above-mentioned side-chain type polymer liquid crystal can be usually produced by polymerizing a polymerizable mesogenic monomer 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. Chem. , 179, p2
73 (1978), Eur, Polym. J. , 18,
p651 (1982) and Mol. Cryst. Li
q. Cryst. , 169, p167 (1989). The polymer liquid crystal used in the present invention can be produced in the same manner as in the above method. Examples of the polymerizable mesogen monomer and the mesogen compound capable of addition reaction include biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, phenylpyrimidine, diphenylacetylene, and biphenylbenzoate. And various compounds in which an acrylate, methacrylate or vinyl group is bonded to a rigid molecule (mesogen) such as cyclohexylbiphenyl or terphenyl, preferably via an alkyl spacer having a predetermined length. It can be mentioned as a typical thing.

[0007] Representative structural examples of these compounds are shown below. These are typical examples of the structure, and the present invention is not limited thereto. CH ₂ ＣC (R ^a ) -COO- (CH ₂ ) _l -OA CH ₂ ＣC (R ^a ) -COO-A CH ₂ ＣＨCH- (CH ₂ ) _l -OA (wherein ^Ra represents hydrogen or a methyl group, l represents an integer selected from 1 to 30, and A represents a mesogen group having the following structure.

[0008]

Embedded image (Wherein X and Y are each a single bond, -N = N-,
-N (→ O) = N-, -CH = N-, -N = CH-,-
COO—, —C (C ＝ O) —, an ethynylene group, and R ¹ represents an alkoxy group, a halogen atom,
Represents a group selected from a cyano group, a carboxyl group, and an alkyl group, p represents an integer selected from 1 to 5, and when p is 2 or more, R ¹ may be different. )

The polymer liquid crystal of the present invention can be produced by copolymerizing or co-adding the above-mentioned compound having a reactive group in addition to the mesogen compound. As the compound having a reactive group used,
(Meth) acrylic acid, ω-carboxy-polycaprolactone-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, mono (meth) acrylate phthalate, 2- (meth) acryloxyethyl (2-hydroxyethyl) phthalate, 4- (meth)
Acryloxyalkyloxy-benzoic acid,
Glyceryl (meth) acrylate, hydroxy-substituted styrene, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, glycidyl (meth)
Examples thereof include acrylate, 2-propen-1-ol, and 5-hexen-1-ol.

After the above mesogen compound is copolymerized or co-added with the mesogen compound, another reactive group may be introduced to convert the reactive group. For example, a hydroxyl group introduced by copolymerizing hydroxyethyl (meth) acrylate can be reacted with (meth) acrylic acid or the like to introduce a polymerizable group into a polymer side chain. Furthermore, vinyl acetate can be polymerized and then hydrolyzed to be converted to a hydroxyl group. The one shown here is 1
It is an example and is not limited in any way. In order to copolymerize the above compound with a mesogen monomer or to co-add it to a polymer liquid crystal, 0.1 to 70 mol% as a monomer unit is used.
Is preferably used. The weight average molecular weight of the polymer liquid crystal used in the present invention is in the range of 1,000 to 1,000,000, and particularly preferably in the range of 10,000 to 500,000. Also,
In the production of the polymer liquid crystal of the present invention, in addition to the two kinds of the mesogen compound and the compound having a reactive group, it is also preferable to carry out copolymerization or co-addition of various non-mesogen compounds as the third component. . Compounds that can be used as the third component include, for example, alkyl (meth) acrylate and its derivatives, styrene and its derivatives, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, vinylpyrrolidone, 1-hexene and 1-hexene.
Octene and the like can be mentioned, and each compound can be used in plural kinds. Using these compounds is
Useful for controlling multi-domain structures and thermal properties.
The copolymerization ratio when the third component is used can be variously changed depending on the desired properties, but the content of the mesogenic monomer is preferably in the range of 40 to 99% by weight, more preferably 60 to 99% by weight. Range. In addition, these copolymerization reactions can take various known forms such as random copolymerization, graft copolymerization, and alternating copolymerization, and are not particularly limited. Polymer liquid crystals having a reactive group are produced as described above, and in the present invention, a cross-linking reaction is performed using these polymer liquid crystals.

Next, it is preferable to use a catalyst and a polyfunctional reactive compound as the reactive compound to be added for accelerating the crosslinking reaction of the polymer liquid crystal. As the catalyst, it is preferable to use various ultraviolet polymerization initiators, thermal polymerization initiators and the like. As the polyfunctional reactive compound, it is preferable to use a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional aldehyde compound, a polyfunctional amine compound, a polyfunctional carboxyl compound, or the like. The crosslinking reaction catalyst and the polyfunctional reactive compound are preferably added in the range of 0.01 to 20% by weight based on the polymer liquid crystal. This cross-linking reaction is performed by applying heat to the polymer liquid crystal composition to which the above-described various compounds are added, but light or an electron beam may be applied together with the heat.

Further, various components can be added to the polymer liquid crystal composition for the purpose of improving various properties of the polymer liquid crystal. 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 recording contrast, anthraquinone-based
Various dichroic dyes such as styryl, azomethine and azo may be added. Various fluorescent dyes may be added for the purpose of improving light scattering. Furthermore, when recording is performed using laser light, various laser light absorbing dyes (when using a general semiconductor laser of 780 to 830 nm, near infrared absorbing dyes such as phthalocyanine, squarylium, and azurenium can be used) Is preferably added. The above-mentioned various components are preferably added to the composition containing the polymer liquid crystal in the range of 0.01 to 5% by weight. Furthermore, low-molecular liquid crystal compounds are
It can be added in the range of 0% by weight.

The polymer liquid crystal composition of the present invention has a multi-domain structure in a temperature range where the composition exhibits a liquid crystal phase. The “multi-domain structure” refers to a structure including a plurality of minute regions having different optical properties.
Each domain that makes up this multi-domain
It is formed mainly by the difference in the orientation of the side chain liquid crystal molecules inside the domain. 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. it can.
The multi-domain structure is an aggregate of domains exhibiting such optical anisotropy. In order to improve the light scattering property of the polymer liquid crystal, it is desirable that the orientation direction of each domain is random. In order to use this multi-domain structure as a light scattering layer, it is desirable that the size of each domain is an aggregate having a size about the wavelength of visible light. The preferred size of the domain diameter is specifically such that the maximum value of the number distribution of the domains is 3 μm or less, preferably 1 μm or less, and more preferably 100 to 600 nm. Also,
It is desirable that the domain diameter distribution range is also substantially uniform such that the difference between the minimum domain diameter and the maximum domain diameter is 3 μm or less, preferably 1 μm or less, and more preferably about 500 nm or less. The multi-domain structure having the size and the distribution range in this range is preferable because it strongly scatters the wavelength of visible light and increases turbidity.

Next, a heat treatment method for controlling the multi-domain structure of the polymer liquid crystal composition of the present invention will be described. In the multi-domain structure of the polymer liquid crystal composition, the size and density of the domain can be changed according to the external temperature. That is, the multi-domain structure can be controlled by heat treatment, and can be changed to a state having higher optical characteristics such as light scattering. This heat treatment method for controlling the multi-domain structure involves not only heat treatment at a single temperature for a fixed time, but also operations such as changing the temperature continuously or changing the temperature stepwise with time. It is preferred to carry out. Specifically, the heat treatment can be performed by holding the polymer liquid crystal composition in a constant temperature furnace at a predetermined temperature for a predetermined time, or by controlling the constant temperature furnace to change the temperature with time. When the polymer liquid crystal layer is produced by a continuous coating method, hot air of a predetermined temperature is blown by a plurality of dryers (blast dryers) set at different temperatures, or passes through a constant temperature furnace provided in the middle of the line. By doing so, heat treatment can also be performed.

When the cross-linking of the polymer liquid crystal composition proceeds, the multi-domain structure is almost fixed in the structure before the cross-linking, so that the size of the domain does not change, and it becomes difficult to control the multi-domain structure. Therefore, in order to improve the optical properties of the polymer liquid crystal composition, heat treatment for controlling the multi-domain structure should be performed before the start of the crosslinking reaction, that is, before the heat treatment for crosslinking the polymer liquid crystal composition. Is preferred. The heat treatment for controlling the multi-domain structure may be performed at a temperature at which the movement of the main chain of the polymer compound in the polymer liquid crystal composition becomes active, that is, at a temperature range in which the polymer liquid crystal composition exhibits a liquid crystal phase. Most effective.
The temperature range in which the polymer liquid crystal composition exhibits a liquid crystal phase is a temperature range equal to or higher than the glass transition point and lower than the liquid crystal phase-isotropic phase transition point, and varies depending on the type of the polymer liquid crystal composition used. But usually 0 to 200 ° C., preferably 20 to 150 ° C.
It is desirable that the temperature be in the range of ° C. Heat treatment at a temperature closer to the isotropic phase transition point is preferable because the viscosity decreases and the multi-domain structure can be controlled at high speed. The structure of the multi-domain structure obtained by the above heat treatment can be maintained by performing a heat treatment for crosslinking the polymer liquid crystal composition thereafter.
The polymer liquid crystal composition thus obtained is cross-linked to maintain a multi-domain structure, whereby the optical characteristics are stabilized even when used repeatedly, and the reproducibility is greatly improved.

Next, the heat treatment for crosslinking the polymer liquid crystal composition of the present invention will be described. The heat treatment method for crosslinking the polymer liquid crystal composition is not only a heat treatment at a single temperature for a certain period of time, but also the temperature is continuously changed,
A method of changing the temperature stepwise with time can also be adopted. The crosslinking reaction is desirably performed at a heat treatment temperature in the early stage of the heat treatment that is lower than the liquid crystal phase-isotropic phase transition temperature of the polymer liquid crystal composition. This is because, when a polymer liquid crystal composition is heat-treated at a temperature equal to or higher than its liquid crystal phase-isotropic phase transition temperature, it undergoes a phase transition to an optically isotropic and uniform state. This is because the domain structure is destroyed. The liquid crystal phase-isotropic phase transition temperature of the composition varies depending on the composition of the polymer liquid crystal to be used and the like, but the heat treatment for crosslinking the polymer liquid crystal composition is usually 200 ° C. or lower, preferably 150 ° C. or lower, more preferably Preferably, the temperature is lower than 80 ° C. Also,
In the latter half of the heat treatment, that is, at the time when the cross-linking is almost completed, it is preferable to complete the cross-linking by performing a heat treatment at a temperature equal to or higher than the liquid crystal phase-isotropic phase transition temperature of the polymer liquid crystal composition. The time required for this heat treatment varies depending on the heat treatment temperature and the type of the polymer liquid crystal composition, but is in the range of 1 minute to 300 hours, preferably in the range of 1 hour to 48 hours.

The heat treatment temperature for controlling the above-mentioned multi-domain structure is desirably higher than the heat treatment temperature for crosslinking the polymer liquid crystal composition. When performing the two-step heat treatment, the heat treatment time for controlling the multi-domain structure is often shorter than the heat treatment time for crosslinking the polymer liquid crystal composition. Also, in general,
The domain size changes more at higher temperatures than at lower temperatures. From the above, when the heat treatment temperature for cross-linking is lower than the heat treatment temperature for controlling the domain structure, the domain structure that has been heat-treated to a desired size is subjected to heat treatment for cross-linking for a long time. Does not change, and a material having desired optical characteristics can be obtained. As described above, in order to improve the optical characteristics of the optical element, the heat treatment temperature for controlling the multi-domain structure needs to be higher than the heat treatment temperature for crosslinking the polymer liquid crystal composition. In the present invention, by employing the heat treatment method described above,
After forming the polymer liquid crystal composition having a high light scattering multi-domain structure, the polymer liquid crystal composition is cross-linked to stabilize the multi-domain structure and always exhibit stable high light scattering. An optical element can be obtained.

Next, in the present invention, a sheet-like base material as a support base material for an optical element will be described. As the sheet-like base material, various polymer films such as polyvinyl chloride, polypropylene, polyester (PET or the like), and polyimide, metal films, paper, and the like can be used. Also, PE
Colored film and PE in which dye is dispersed in T film etc.
It is also preferable to use a film in which a colored layer is provided on a T film or the like, or a vapor-deposited film in which a metal layer having a high reflectance is vapor-deposited on the surface of a substrate. These layers are also used as a light absorbing layer, a colored layer and a light reflecting layer can do. Furthermore, it is also possible to use a substrate with electrodes as the substrate. Light absorbing layer,
The thickness of the coloring layer and the light reflecting layer is 0.001 to 100 μm.
m. The polymer liquid crystal layer can be formed on the sheet-like base material by a general method such as a coating method using a solvent and a hot-melt coating method. The thickness of the polymer liquid crystal layer is not particularly limited, but is preferably selected from the range of 1 to 100 μm, and particularly preferably selected from the range of 2 to 50 μm.

Next, the surface protective layer of the present invention will be described. Characteristics required for the surface protective layer include abrasion resistance,
In addition to having various properties such as heat resistance, pressure resistance, surface friction, and surface lubricity, adhesiveness is low at a heat treatment temperature for crosslinking a polymer liquid crystal. Examples of materials that meet these conditions include thermosetting resins such as ultraviolet curable resins and electron beam curable resins that are excellent in mechanical strength such as pressure resistance, abrasion resistance and heat resistance. Since the ultraviolet curing resin and the electron beam curing resin form a film by a polymerization reaction of a polyfunctional monomer and a polyfunctional oligomer,
A tough surface protective layer having high mechanical strength can be obtained.

Materials used for the surface protective layer of the present invention include polyester acrylate, polyester methacrylate, polyether acrylate, polystyryl methacrylate, polyether methacrylate, urethane acrylate, and epoxy acrylate (particularly, bisphenol A type and bisphenol F type). , Epoxy acrylates having a skeleton of bisphenol S type and phenol novolak type epoxy acrylate), polycarbonates, polybutadiene acrylates, silicone acrylates, melamine acrylates, etc., having 1 to 10 functional groups. . Also, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate,
Monofunctional monomers and polyfunctional monomers such as 1,6-hexadiol acrylate and tetraethylene glycol diacrylate are also preferable. It is also preferable to use these materials in various combinations.

The surface protective layer may be formed by laminating a plurality of layers having different compositions. In particular, with a single-layer surface protective layer, it is difficult to simultaneously satisfy the adhesion at the interface with the polymer liquid crystal layer and the lubricity on the surface of the optical element. The first
A plurality of surface protective layers having different functions, for example, by forming a surface protective layer on the optical element and then forming a second surface protective layer on the surface to improve the lubricity of the optical element surface. Is also preferred. In addition, since the resin material has a property of low adhesiveness at a heat treatment temperature for crosslinking a polymer liquid crystal, the glass transition temperature (Tg)
Is preferably higher than the heat treatment temperature, and Tg is 80 ° C.
It is preferable that it is above. The thickness of the surface protective layer varies depending on the material used, but is in the range of 0.1 to 10 μm, preferably 0.2 to 5 μm, more preferably 1 to 2 μm.

The method for forming the surface protective layer of the present invention includes:
In the case of an ultraviolet curable resin, a mixture of the above oligomer or monomer and a photopolymerization initiator, preferably at a ratio of 2 to 5% by weight, is dissolved in a solvent or the like on a recording layer made of a polymer liquid crystal composition. A method in which the viscosity is adjusted, the obtained solution is applied, heated if necessary, and cured by irradiating ultraviolet rays can be applied. It is also preferable that the surface protective layer is formed with a plurality of surface protective layers by forming second and third surface protective layers thereon as necessary.

In the second method of the method for producing an optical element of the present invention, first, the above-mentioned polymer liquid crystal layer is formed on a sheet-like base material as a support base material using a continuous coating machine or the like. A first heat treatment step for controlling the multi-domain structure is performed. Next, after forming a surface protective layer on the polymer liquid crystal layer, a second heat treatment step for crosslinking the polymer liquid crystal layer is performed. After these steps are completed, if necessary, a second and a third surface protective layer can be further formed on the surface protective layer. In addition,
In the first method, the heat treatment for cross-linking the polymer liquid crystal layer is performed by subjecting the sheet-like substrate on which the polymer liquid crystal layer is formed to a heat treatment.
The second method is performed in a state of being wound in a roll shape.
Also, it is preferable that the
Accordingly, the production efficiency of the optical element can be improved. In this case, since the surface protective layer is formed on the polymer liquid crystal layer, the surface adhesion of the optical element can be reduced. Therefore, even when this optical element is wound into a roll, the superposed surface of the optical element strongly adheres to the back surface of the sheet-shaped substrate in contact with the upper surface, and the surface of the substrate coated with the polymer liquid crystal layer is applied. The phenomenon of peeling off from the surface does not occur. After these steps are completed, if necessary, a second and a third surface protective layer can be further formed on the surface protective layer. For example, the first surface protective layer is used to cross-link the polymer liquid crystal layer in the second stage to improve the surface release property during heat treatment, and the second surface protective layer is used for heat resistance of the optical element. By further forming the third surface protective layer to improve the abrasion resistance of the optical element, various characteristics of the optical element can be improved.

[0024]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Example 1 190 g of 4-acryloxyhexyloxy-4'-cyano-biphenyl as a mesogenic monomer, 10 g of 2-hydroxyethyl acrylate as a non-mesogenic monomer having a reactive group, and azobisisobutyro as a polymerization initiator Polymerization was carried out using nitrile (AIBN) and tetrahydrofuran as a solvent. The obtained polymer solution was purified by repeating precipitation three times using ethyl alcohol as a precipitation solvent to obtain 190 g of a polymer liquid crystal represented by the following structural formula (1). The Ti (liquid crystal phase-isotropic phase transition temperature) of the obtained polymer liquid crystal was about 110 ° C.

Embedded image 1.0 g of Coronate HX (manufactured by Nippon Polyurethane), a polyfunctional isocyanate compound as a crosslinking agent, and 60 g of methyl ethyl ketone as a solvent
Is added to a 100 μm-thick aluminum vapor deposited P
On the aluminum deposition surface of the ET film, coating is performed by a continuous coating device having a die coater head, and the solvent is dried and removed using a drier installed in the coating device. A first-stage heat treatment for controlling the multi-domain structure was carried out to form a polymer liquid crystal layer having a thickness of about 6 μm and a width of 250 mm and a length of 10 m, which was wound into a roll. This polymer liquid crystal layer was cloudy. Next, an ultraviolet curable composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied as a surface protective layer using the above continuous coating apparatus, and cured by irradiation with a metal halide lamp to obtain a film thickness of about 1 μm.
Was formed on the polymer liquid crystal layer, and this was wound into a roll again. Thereafter, as a second stage heat treatment for crosslinking the polymer liquid crystal composition, the mixture was reacted in an oven at 50 ° C. for 24 hours to perform crosslinking, thereby producing an optical element.
After the heat treatment in the second stage, the film was drawn out of the roll form, but no adhesion between the films and no offset to the back surface of the film occurred.

Example 2 After the first stage heat treatment, a surface protective layer having a film thickness of about 1 μm was formed on a polymer liquid crystal layer using soluble nylon (trade name: CM4000, manufactured by Toray Industries, Inc.) as a material for the surface protective layer. And
After the heat treatment in the second step, an ultraviolet curing composition (trade name: Aronix UV, manufactured by Toagosei Co., Ltd.) is applied as a second surface protective layer on the surface of the soluble nylon surface protective layer, and cured by irradiation with a metal halide lamp. By
An optical element was produced in the same manner as in Example 1, except that a second surface protective layer having a thickness of about 1 μm was formed. In this case, no offset occurred as in the case of the first embodiment.

Comparative Example 1 A polymer liquid crystal layer was formed in the same manner as in Example 1, a heat treatment for controlling the multi-domain structure in the first stage was performed, and this was wound into a roll to form a surface protective layer. Without performing the heat treatment, a second stage heat treatment was performed. After the second stage heat treatment for crosslinking the polymer liquid crystal composition, when the sheet was to be pulled out from the roll form, the films adhered to each other, and the polymer liquid crystal layer was detached and the film was wrinkled.

[0027] Similarly to form a polymer liquid crystal layer as in Example 3 Example 1, without performing the heat treatment for controlling the multi-domain structure of the first stage, Ri taken up in a roll form, a surface protective layer It was
After was performed only heat treatment of the second stage cross-linking the high-molecular liquid crystal composition is wound again into a roll. When the sheet was pulled out of the roll form, no adhesion between the films and no offset to the back of the film occurred.

Example 4 The first step heat treatment for controlling the multi-domain structure was performed at a temperature of 30 ° C., and the first step heat treatment was lower than the second step heat treatment. An optical element was manufactured. When the sheet was pulled out of the roll form, no adhesion between the films and no offset to the back of the film occurred.

Example 5 An optical method was performed in the same manner as in Example 1 except that the first heat treatment temperature for controlling the multi-domain structure was not lower than the liquid crystal phase-isotropic phase transition temperature of the polymer liquid crystal at 130 ° C. An element was manufactured. The sheet was pulled out from the roll form, but no adhesion between the films and no offset to the back of the film occurred.

The optical elements produced in the above Examples and Comparative Examples were evaluated. (Offset performance) The state of occurrence of the offset was determined by measuring the area of the liquid crystal layer adhering to the back surface of the film when the obtained roll-shaped optical element was pulled out, and when the adhering area was zero, it was determined that no offset occurred. . From the results of comparison between Example 1 and Example 2 and Comparative Example 1, since the optical element obtained by the manufacturing method of the present invention does not cause offset, the production efficiency of the optical element is very high, and the separation of the polymer liquid crystal is performed. It was found that an optical element having a uniform film thickness without defects could be manufactured. (Reproducibility of Light Scattering Control) In order to record information on the optical element, a thermal printer was used to provide an area (transparent state) where light scattering was reduced. The information was erased by using a heat roller set at 130 ° C. to return to a state where light scattering was large (light scattering state). Regarding the optical element, the optical density immediately after fabrication and the reflection optical density in a cloudy state after repeating recording / erasing 100 times were X-write 404 (X-write 404).
(Manufactured by the company). Table 1 shows the results.

[0031]

[Table 1]

The following can be understood from the results of the above Examples and Comparative Examples and Table 1. That is, the optical elements obtained in Examples 1 and 2 have a surface protective layer formed on the polymer liquid crystal layer as compared with those obtained in Comparative Example 1, so that the polymer liquid crystal composition is crosslinked. Even if the heat treatment to be performed is performed in a roll state, there is an advantage that production can be efficiently performed without problems such as adhesion. Further, in the examples, it is preferable to perform the heat treatment in two steps rather than in one step because the optical density becomes lower and the white turbidity becomes more excellent (in comparison with Examples 1 and 3). ). Further, it is preferable that the heat treatment temperature in the first stage is higher than the heat treatment temperature in the second stage because the cloudiness is more excellent (Examples 1 and 4).
From the comparison). Furthermore, it is preferable to perform the first heat treatment temperature for controlling the multi-domain structure in a temperature range in which the polymer liquid crystal composition shows the liquid crystal layer, since the opacity is more excellent (Example 1). And 5). When the surface of the surface protective layer was observed with a microscope for the samples of Examples 1 and 2 after recording / erasing was repeated 100 times, several cracks having a width of about 5 μm and a length of about 50 μm were found in Example 1. In contrast to Example 2, no surface flaw was observed in Example 2. From the results, it is understood that the strength of the surface protective layer is increased by laminating a plurality of surface layers.

[0033]

According to the present invention, the surface of an optical element obtained by performing a heat treatment for cross-linking a polymer liquid crystal with a surface protective layer formed on the surface of a polymer liquid crystal layer has an adhesive property. It will be suppressed. Also, if you row to a heat treatment at wound form into a roll, because it is possible to prevent a phenomenon such that the adhesive and in that the sheet-like substrate such as a film which is in contact, to improve the production efficiency of the optical element it can. Prior to crosslinking the polymer liquid crystal layer,
By performing the heat treatment for controlling the crystal structure, it is possible to produce an optical element exhibiting stable and high light stability and having improved durability and recording / erasing characteristics. , An optical recording medium, an optical modulation element, and a reversible display recording element.

──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Takashi Uematsu 1600 Takematsu, Minamiashigara-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-1-134425 (JP, A) JP-A-5-257126 ( JP, A) JP-A-4-218024 (JP, A) JP-A-5-117532 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/1333 G02F 1/13 101 G02F 1/13 505 G09F 9/00-9/46 B41M 5/26

Claims (6)

(57) [Claims] 1. A polymer liquid crystal layer formed on a sheet-like substrate.
After forming a surface protective layer on the sheet, the sheet-shaped substrate is rolled.
The polymer liquid crystal layer was crosslinked in a state of being wound into a shape.
For producing optical elements characterized by performing a heat treatment for
Law. 2. A polymer liquid crystal layer is formed on a sheet-like substrate.
And the first to control the multi-domain structure of the polymer liquid crystal
After the heat treatment, a surface protective layer is formed on the polymer liquid crystal layer,
Further, a second heat treatment for crosslinking the polymer liquid crystal layer is performed.
A method for manufacturing an optical element. 3. Heat for controlling a multi-domain structure
The processing temperature is the heat treatment temperature for crosslinking the polymer liquid crystal layer.
3. The optical element according to claim 2, wherein the optical element has a degree higher than the degree.
Manufacturing method. 4. A heat treatment for crosslinking a polymer liquid crystal layer.
At a temperature lower than the liquid crystal phase-isotropic phase transition temperature of the polymer liquid crystal.
3. The optical element according to claim 1, wherein
Production method. 5. A liquid crystal polymer layer comprising a mesogen monomer unit and
Including high-molecular liquid crystals containing non-mesogenic monomer units
The composition according to claim 1, wherein the composition comprises a composition.
A method for manufacturing an optical element. 6. A polymer liquid crystal layer is formed on a sheet-like substrate.
And the first to control the multi-domain structure of the polymer liquid crystal
Heat-treating a first surface protective layer on the polymer liquid crystal layer;
Is formed, a second liquid for crosslinking the polymer liquid crystal layer is formed.
Heat treatment is performed, and then a second heat treatment is performed on the first surface protection layer.
Optical element characterized by forming a surface protective layer of No. 2.
Manufacturing method.