JP2887082B2 - Information recording medium and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium capable of repeatedly performing recording and erasing by an external stimulus such as heat, an electric field, a magnetic field, or light, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Recently, attention has been focused on a recording material and a recording medium capable of reversibly forming and erasing an image by an external stimulus. For example, as a heat-sensitive recording material capable of reversibly recording and erasing information by heat, a heat-sensitive recording material composed of a composite film in which a low-molecular organic compound is dispersed in a high-molecular compound (JP-A-54-119377, No. 57-82087), those comprising a polymer liquid crystal (JP-A-59-10930, JP-A-69-1930).
JP-A-3-223066, JP-A-62-14114, JP-A-2-2513) and those obtained by blending a plurality of polymer compounds (JP-A-63-37994, JP-A-63-23234). Gazettes) are known. In addition, a reversible material capable of thermally developing and decoloring by using a material having a binder as a main component, such as a color developing agent and a polymer compound, which develops or reduces color by thermally reacting with a leuco compound on a support. Thermal recording medium (Japanese Unexamined Patent Publication No. 2-188)
294) is known. Among these, the organic low molecular weight compound / polymer compound composite material and the polymer liquid crystal whose light scattering degree changes reversibly have excellent durability and thus are highly practical. The above materials are
Usually, it is formed as a recording layer on a sheet-like substrate such as a plastic film, and is used as a recording medium formed by forming a protective layer on the recording layer. JP-A-62-14114, JP-A-2-2513, Polym. Commu
n. , Vol. 24, 364 (1983), Japan
Display, p260 (1986) and the like.

[0003]

Generally, an information recording medium having a recording layer whose light scattering degree is reversibly changed by an external stimulus is a method of applying a recording material onto a sheet-like base material such as a film. Produced by As this film, a wound material is usually used. To form a recording layer on the film, a fixed film is supplied from the wound material to a recording layer forming step (coating, drying), and the recording is performed. The film on which the layer is formed is stored again as a roll having the original shape. Further, when a protective layer or the like is formed on the recording layer, the same steps as those for forming the recording layer are repeated using the wound material on which the recording layer is formed. The information recording medium is manufactured by cutting a roll obtained by the above-described method into a desired size. However, in the step of forming a recording layer on a film and then forming the same into a roll, depending on the type of material forming the recording layer, the recording layer may be adjacent to the film surface (the surface on which the recording layer is not formed). As a result, the recording layer is detached and the film is deformed.
Furthermore, when the recording layer is cross-linked by applying heat for the purpose of improving the properties of the information recording medium, the phenomenon of adhesion to an adjacent film surface generally occurs because heat treatment is performed in a wound state. There was a problem of further expansion. The present invention has been made in order to solve the above-described problems in the related art, and an object of the present invention is to form a sheet-like base material on which a recording layer is formed in a winding process in a process of manufacturing an information recording medium. It is an object of the present invention to provide a laminated structure of an information recording medium capable of preventing adhesion between a recording layer and a sheet-like substrate, and a method for producing the same.

[0004]

The method for manufacturing a information recording medium of the present invention In order to achieve the above object, according to one side of the sheet-like substrate, a low adhesion low adhesion layer is formed with respect to the recording layer, then the other Face to face, lord
Polymer liquid crystal with liquid crystalline molecules bonded to the chain or side chain
More will, after degree of light scattering to form a recording layer that changes reversibly by an external stimulus, it shall be the said heat treating the sheet laminate formed in the state of the winding-like material.

[0005] First, formed by the manufacturing method of the present invention.
The configuration of the information recording medium described above will be described with reference to the drawings. 1 (a) to 1 (c) show the results of the method of the present invention .
The aspect of the formed information recording medium is shown. In FIG.
1 is a recording layer, 2 is a sheet-like substrate, 3 is a low adhesive layer, 4 is a protective layer, and 5 is a light reflection layer. FIG. 1A shows a configuration in which a recording layer 1 is formed on one surface of a sheet-like substrate 2 and a low-adhesion layer 3 is formed on the other surface of the substrate. FIG. 1 (b)
1 shows a configuration in which a protective layer 4 is formed on a recording layer in addition to the configuration shown in FIG. 1C has a configuration in which a light reflection layer 5 is formed between the recording layer 1 and the sheet-like substrate 2 for the purpose of improving the degree of light scattering, in addition to the configuration of FIG. It is shown.

Next, the semiconductor device formed by the manufacturing method of the present invention is formed.
Each layer constituting the information recording medium described above will be described. The recording layer 1 of the information recording medium according to the present invention, in which the degree of light scattering is reversibly changed by an external stimulus, is capable of recording and erasing visible information reversibly, and has a main chain or a side chain. High molecular weight with liquid crystalline molecules bonded to the chains
It consists child liquid crystal, light scattering degree of reversibly changed by applying heat or the like from the outside, Ru der those opaque state and a transparent state can be repeated each alternately.

[0007]

[0008]

As the polymer liquid crystal, there are known a main chain type polymer 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. However, in the present invention, it is particularly preferable to use a side chain type polymer liquid crystal. As the side chain type polymer liquid crystal used in the present invention, it is preferable to use a liquid crystal composed of a repeating structural unit represented by the following structural example 1, structural example 2 or structural example 3.

Embedded image (In the formula, R represents a hydrogen atom or a methyl group, n represents an integer of 1 to 30, and A represents a mesogen group selected from the following (a) to (k).)

[0010]

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. )

In the present invention, it is preferable to use a phase-separated polymer liquid crystal obtained by copolymerizing a mesogenic monomer and a non-mesogenic monomer and having a non-mesogenic component in the side chain. The polymer liquid crystal is disclosed in JP-A-4-218024 and JP-A-6-1886.
No. 6 discloses this. When these polymer liquid crystals are used, the contrast of a recorded image can be greatly improved, and the heat-sensitive characteristics can be optimized. Further, in the present invention, it is preferable to use a cross-linked polymer liquid crystal,
Crosslinked polymer liquid crystals having a multi-domain structure are particularly preferred. By cross-linking the polymer liquid crystal as a multi-domain structure composed of an aggregate of domains of a specific size having optical anisotropy, it is possible to obtain a liquid crystal capable of realizing high-speed and stable recording and erasing. The multi-domain structure refers to a structure including an aggregate of a plurality of minute domains having optical anisotropy (birefringence), and is a structure that strongly scatters light. In particular, the multi-domain structure is preferable since the light is most strongly scattered when the diameter of the domain is in the range of 0.2 to 1.5 μm at the maximum of the number of distribution of the domain.

The crosslinking of the polymer liquid crystal is performed by forming the polymer liquid crystal as a recording layer and then forming the obtained sheet-like laminate into a roll.
It can be performed by a method of winding into a state and crosslinking by an external stimulus such as heat, light, or an electron beam. In the present invention, examples of the polymer liquid crystal used for crosslinking include a compound containing a reactive group as one component of a main chain or a side chain. In these compounds, crosslinking can be carried out by utilizing a reactive group and adding a catalyst and a polyfunctional reactive compound as required. Specific examples of the reactive group include a vinyl group, an acrylate group, a methacrylate group, an addition or a polymerizable group such as an isocyanate group such as an epoxy group, a hydroxyl group, an amino group, an acid amide group, a thiol group, and a carboxyl group. Groups, sulfonic acid groups, phosphoric acid groups, metal alcoholate groups, magnesium halide groups (Grignard reagent) and the like are preferred. As the catalyst, various ultraviolet polymerization initiators, thermal polymerization initiators and the like, as the polyfunctional reactive compound, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, a polyfunctional melamine compound, a polyfunctional aldehyde compound,
Polyfunctional amine compounds and polyfunctional carboxyl compounds are preferably used. As an example of a technique for crosslinking a polymer liquid crystal, see Makromol. Chem. Rap
id Commun. , Vol. 2,317 (198
1), Makromol. Chem. , Vol. 66
7, 188 (1987), Angew. Chem. Ad
v. Mater. , Vol. 101, 1437 (198
9), Makromol. Chem. , Vol. 18
7, 1915 (1989).

The 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. The technology relating to these is described in Makromol. Chem. , 179, p
273 (1978), Eur. Polym. J. , 1
8, p651 (1982), 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.

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 is the same as the mesogen group A in the structural example 1.)

In the preparation of the polymer liquid crystal of the present invention, the non-mesogenic monomer and the non-mesogenic compound to be copolymerized or co-added with the mesogenic monomer are useful for improving the contrast of a recorded image and optimizing thermal characteristics. It is preferably a compound, for example, alkyl (meth) acrylate and its derivatives, styrene and its derivatives, vinyl acetate, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, vinyl pyrrolidone,
(Meth) acrylic acid, which is a compound having a reactive group for post-crosslinking, such as 1-hexene and 1-octene, 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, phthalic acid mono (meth) acrylate,
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) acrylate, 2-propen-1-ol, 5-hexen-1-ol and the like can be mentioned. However, the present invention is not limited to this. In order to copolymerize the above compound with a mesogenic monomer or to co-add it to a polymer liquid crystal, 0.1 to 7
It is preferable to use it in the range of 0 mol%.

The polymer liquid crystal of the present invention is produced by using the above-mentioned monomer and reactive compound, by a homopolymerization reaction such as radical polymerization or ionic polymerization, a copolymerization reaction, or an addition reaction to a reactive polymer. Can be. The weight average molecular weight of the polymer liquid crystal used is 1,
It is preferably in the range of 000 to 1,000,000, and especially 1
The range of 10,000 to 500,000 is preferable. Also, the copolymer may be in various forms such as random, block, graft, and alternating.

The principle of a phase change type recording / erasing method using thermal control on the information recording medium of the present invention will be described.
The recording layer of the information recording medium having a polymer liquid crystal initially has an optically anisotropic multi-domain structure and thus exhibits a light scattering (white turbidity) state. When recording on this information recording medium, the polymer liquid crystal is converted into an isotropic (transparent) state by partial heating using a thermal head or laser light,
Thereafter, when the material is rapidly cooled, the heated portion is fixed in a glass state while being isotropic, and the recording portion becomes transparent. On the other hand, in the case of erasing, it can be erased by cooling after heating and then returning to the initial light scattering state as compared with the time of recording. By repeating the above operation, recording / erasing can be performed reversibly many times. For example, when a thermal head is used as a heating unit for performing recording / erasing, it can be achieved by controlling a pulse width and energy applied to the thermal head. Conversely, the recording layer can be set to be in a transparent state at the initial stage and the recording can be performed in a cloudy state. Further, this recording / erasing method can also be carried out by utilizing an electric field or a magnetic field.

[0018] High molecular liquid crystal obtained by the present invention described above, in order to improve various properties can be added to various components. For example, various antioxidants such as hindered amine and hindered phenol may be added for the purpose of improving weather resistance, and for improving the recording 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 using laser light, various laser light absorbing dyes (in the case of using a general semiconductor laser having a wavelength of 780 to 830 nm, near infrared absorbing dyes such as phthalocyanine, squarylium and azurenium). Can be used). It is preferable that each of the above-mentioned various components is added to the composition in a range of 0.01 to 5% by weight. In addition, a low-molecular liquid crystal compound can be further added to the high-molecular liquid crystal in the range of 1 to 20% by weight.

Next, as the sheet-like substrate 2 of the present invention,
Polyester resin, polyether resin, polyurethane resin, polyamide resin, acrylic resin, polyimide resin,
It is preferable to use a film of a resin represented by a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polycarbonate resin, a Teflon resin, various metal films, paper, coated paper, and the like. The thickness of the sheet-like substrate used is 1 to
It is selected from the range of 1,000 μm, but preferably
It is in the range of 0 to 200 μm.

The low-adhesion layer 3 is formed of a material selected from an organic compound, an inorganic compound and a polymer compound, but hardly adheres to the material constituting the recording layer (low adhesion). G) material, and it is particularly preferable to use a material having a lower surface free energy than the material constituting the recording layer. Materials used include waxes, oils, inorganic compounds, silicone compounds, silane coupling compounds, silicone resins, silicone-modified acrylic resins,
Teflon, fluorine-based resins such as polyvinyl fluoride and polyvinylidene fluoride and the like are preferred. Among them, silicone resins and fluorine resins are particularly preferably used. The low-adhesion layer is preferably formed by sputtering, depositing, adsorbing, or applying these materials on a sheet-like substrate. The thickness of the low adhesion layer is selected from the range of 1 nm to 100 μm, but is preferably 0.1 to 20 μm.

The protective layer 4 is preferably formed on the surface of the recording layer in order to prevent the recording layer from being deteriorated due to repeated recording / erasing. As the protective layer, it is desirable to use a material having high heat resistance, and examples thereof include a fluorine resin, a silicone resin, a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin. The protective layer may be laminated in a plurality of layers, and the thickness thereof is preferably 0.1 to 20.
It is selected from the range of μm. The light reflecting layer 5 is preferably formed between the sheet-like substrate and the recording layer or between the layer having excellent releasability in order to improve the light scattering degree of the recording layer. As the material, a metal film of aluminum, silver, tin, magnesium, gold, platinum or the like is preferably used, and is formed by vapor deposition or sputtering. Its thickness is in the range of 0.001 to 100 μm.

Hereinafter, a method for manufacturing the information recording medium of the present invention will be described with reference to specific examples. (Formation of Low Adhesion Layer) A sheet-like base material wound into a roll is pulled out at a constant speed, and a solvent solution of a material for forming a low-adhesion layer is applied to one surface of the sheet-like base material to form a recording layer. Provide a coating layer having excellent releasability, dry it to form a low-adhesion layer on the sheet-like substrate, and wind the sheet-like substrate having the low-adhesion layer formed on one side thereof. And the original roll. (Formation of a recording layer) A roll of a sheet-like base material having a low-adhesion layer formed on one surface is pulled out at a constant speed, and a recording layer is formed on the other surface on which the low-adhesion layer is formed. By applying a solvent solution of the material to be dried and dried to form a recording layer on the sheet-like substrate, a low adhesion layer on one side,
Further, the sheet-like base material on which the recording layer is formed on the other surface is wound up again to obtain the original roll. The coating for forming each of the above-mentioned layers can be performed by a general coating method such as a blade coater, a gravure roll coater, and a die coater. When a protective layer is formed on the recording layer, it can be formed in the same manner as described above.

[0023]

【Example】

(Formation of Low Adhesion Layer) Aluminum evaporated polyethylene terephthalate (PET) film (width 40 cm, thickness 7)
5 μm), the film is pulled out from the wound material, and polyvinylidene fluoride (VDF,
A mixed solution of acetone and cyclohexanone (available from Daikin Co., Ltd.) was continuously applied using a gravure roll and dried to form a low-adhesion layer having a thickness of 2 μm on the PET film, which was wound. (Formation of Recording Layer) As a mesogen monomer, 4-acryloxyhexyloxy-4'-cyano-biphenyl 19
Polymerization was carried out using 0 g, 10 g of 2-hydroxyethyl acrylate as a reactive monomer, 1.0 g of azobisisobutyronitrile (AIBN) as a polymerization initiator, and 400 ml of methyl ethyl ketone (MEK) as a solvent. The obtained polymer was purified by repeating precipitation three times using ethyl alcohol as a precipitation solvent to synthesize a polymer liquid crystal represented by the following structural formula (1).

Embedded image

4 g of 4,4'-diphenylmethane diisocyanate which is a polyfunctional isocyanate compound as a crosslinking agent and ME as a solvent
A solution was prepared by adding 300 g of K / toluene (weight ratio: 1: 1). The film is pulled out from the roll of the above-mentioned aluminum-deposited PET film having the low-adhesion layer formed thereon, and the polymer liquid crystal composition solution is continuously applied to the other surface of the low-adhesion layer using a gravure roll and dried. , PET
A recording layer having a thickness of 5 μm was formed on the film, and was wound. In order to crosslink the polymer liquid crystal layer in the state of a roll having the recording layer formed thereon, a heat treatment was performed by allowing the polymer liquid crystal layer to stand in a heat-insulating room at 50 ° C. for 24 hours. (Formation of Protective Layer and Preparation of Information Recording Medium) A film was pulled out from the wound material subjected to the above heat treatment, and an ultraviolet curable composition (Aronix UV, manufactured by Toagosei Co., Ltd.) was continuously applied on the recording layer using a gravure roll. A protective layer having a film thickness of about 2 μm was formed by applying the protective layer, followed by curing using a high-pressure mercury lamp. The obtained recording material was cut into a predetermined size to produce an information recording medium.

Comparative Example The same aluminum vapor-deposited film as that of the example was used as a substrate, and a recording layer made of a polymer liquid crystal was formed in the same manner as in the example without forming a low-adhesion layer on the film. . The film was formed into a roll, and heat treatment was performed in the state of the roll to crosslink the polymer liquid crystal. As a result, the recording layer adhered to the PET film, and the film was broken or the recording layer was detached at the time of drawing the film to the next step, and it was difficult to manufacture an information recording medium.

[0026]

According to the method of manufacturing an information recording medium of the present invention ,
Low adhesion with low adhesion to the recording layer on one side of the sheet-like substrate
Form an adhesive layer and then on the other side,
Therefore, a recording layer in which the degree of light scattering changes reversibly was formed.
After that, the formed sheet-like laminate is heat-treated in the state of a roll.
Therefore, the information recording medium can be manufactured very quickly and easily. Obtained by the present invention
The information recording medium can prevent adhesion between the recording layer and the sheet-like substrate even if the information recording medium is in the form of a roll or heat-treated in the state of a roll for the purpose of crosslinking the recording layer. Further, the low adhesion layer, since the use of low surface free energy or surface friction compound, that has excellent properties in antifouling properties and mechanical slip properties.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a configuration example showing an information recording medium formed by a manufacturing method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording layer, 2 ... Sheet-like base material, 3 ... Low adhesive layer, 4 ...
Protective layer, 5 ... light reflecting layer.

Continuation of the front page (58) Field surveyed (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 (3)

(57) [Claims] 1. A low-adhesion layer having low adhesiveness to a recording layer is formed on one surface of a sheet-like substrate, and then on another surface,
Polymer liquid with liquid crystalline molecules bonded to main chain or side chain
Forming a recording layer comprising a crystal and having a light scattering degree reversibly changed by an external stimulus, and then subjecting the formed sheet-like laminate to a heat treatment in a wound state, thereby producing an information recording medium. Method. 2. The method according to claim 1, wherein the recording layer is cross-linked by heat treatment. 3. An information recording medium manufactured by the manufacturing method according to claim 1.