JPH0753948A - Antistatic material and optical recording medium containing the same - Google Patents

Abstract

PURPOSE:To form on an optical recording medium an electron-conductive antistatic thin layer which is transparent and free from moisture, etc., and is less apt to be removed from the medium surface by wiping with a solvent, etc., by treating the medium with an antistatic material comprising a carbazole compound having a specific functional group. CONSTITUTION:The material is a compound having a carbazole ring and a functional group represented by formula I, wherein at least one of X, Y, and Z is -Cl, -OCH3, or -OC2H5. The compound is preferably one represented by formula II, wherein n is a number of 0-20. The surface of an optical recording medium comprising a substrate and, formed thereon, a recording layer and a protective layer in this order is treated with this antistatic material wholly or partly. Before this treatment, the medium is preferably coated with a hard layer, e.g. a (meth)acrylate resin layer, having a pencil hardness of H or harder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an antistatic material capable of forming a conductive thin film layer on a substrate (base material) and subjecting the substrate to a transparent antistatic treatment, and an optical recording containing the antistatic material. Regarding the medium.

[0002]

2. Description of the Related Art Currently,
For optical materials such as optical disk substrates and lenses, polymeric materials such as polycarbonate and polymethylmethacrylate are often used from the viewpoint of moldability and transparency, but the polymeric materials exhibit high insulating properties. There is a problem that it is easily charged and "dirt" occurs when a large amount of dust adheres to the surface of the substrate during storage or use, resulting in an error during use.

Therefore, as measures against the above problems, various antistatic treatments have been proposed in which a hard coating agent having transparency and antistatic property is coated on the pickup surface of the substrate. As the antistatic treatment, it is necessary to subject the surface of the substrate to electroconductivity, and it is roughly classified into a method using a hard coating agent to which a conductive filler is added or a hard coating agent in which a surfactant is kneaded. Then, a method of forming a conductive circuit on the substrate surface by adsorbing water molecules on the substrate surface has been considered.

However, the former method of using a hard coat agent to which conductive filler is added is satisfactory for imparting antistatic property, but in view of its mechanism, a large amount of conductive filler has to be added, resulting in optical characteristics, hardness, There arises a problem that the coating characteristics are deteriorated. On the other hand, the method using a hard coating agent in which a surfactant is kneaded has a problem that the effect is reduced at low humidity where electrification is most likely to occur, and a reactive group is introduced into an antistatic agent to chemically react with the base. Unless it is fixed, bleeding causes turbidity on the surface as it is used, causing a problem that the antistatic property is deactivated.

The cause of the above "dirt" is not only due to charging, but also "dirt" due to the liquid bridge force due to the water adsorbed on the substrate surface or "dirt" due to the adhesive force of oil or the like. Therefore, it is desirable to make the surface of the substrate electrically conductive without increasing the surface energy in order to prevent the complete attachment of dirt. Therefore, a method of surface-treating with an electron conductive material has been considered, and one method is to apply a soluble conductive polymer. Since they are not bonded, there is a problem that the antistatic property is deteriorated by being removed from the substrate surface by wiping with a solvent or the like.

Therefore, an object of the present invention is to form a transparent, antistatic thin film layer having electron conductivity, which is free from environmental dependence such as humidity dependence, on a substrate, and is capable of forming a solvent. An object of the present invention is to provide an antistatic material that is not likely to be removed from the surface of a substrate by wiping or the like, and an optical recording medium containing the antistatic material.

[0007]

As a result of various studies, the present inventors have found that a carbazole compound having a specific functional group can serve as an antistatic material capable of achieving the above object.

The present invention has been made based on the above findings, and includes a compound having a carbazole ring and a functional group represented by the following general formula [Chemical Formula 3] (the same as the above [Chemical Formula 1]) in the molecule. The present invention provides an antistatic material characterized by the following.

[0009]

[Chemical 3]

Further, according to the present invention, in an optical medium in which a recording layer and a protective layer are sequentially formed on a substrate and optical reproduction and recording / reproduction are performed, the entire surface or a predetermined portion of the surface of the optical medium is charged as described above. The present invention provides an optical recording medium comprising a preventive material.

First, the antistatic material of the present invention will be described in detail below. The antistatic material of the present invention comprises a compound having a carbazole ring and a functional group represented by the above general formula [Chemical Formula 3] in the molecule (hereinafter referred to as "compound A").

The carbazole ring contained in the compound A is a group exhibiting conductivity on the surface of the substrate because it forms a π-conjugated system. In the embodiment of the compound A, an unsubstituted carbazole ring, Alternatively, various embodiments such as a derivative or a substitution product of the carbazole ring are possible.

The functional group represented by the above general formula [Chemical Formula 3] is a hydrophilic group (-OH, -COOH, -N) on the substrate surface.
H, —NH ₂ etc.) is a group forming a chemical bond. In the above general formula [3], X, at least one of Y and Z, -Cl, a radical selected from the group consisting of -OCH ₃ and -OC ₂ H _4, the X in addition to this, Y And Z
The group that can be taken is not particularly limited, but for example,
_{-H, -CH 3, -C 2 H} 5 and the like.

As a functional group represented by the above general formula [Chemical Formula 3],
Specifically, --SiCl₃, -SiCl_m(CH
₃)_3-m, -SiCl_m(C₂H_Five)_3-m, -Si (O
CH ₃)₃, -Si (OC₂H_Five)₃Etc. (However, m is
(Representing a number from 0 to 2) is taken into consideration, considering reactivity with a hydrophilic group.
Considering it, it is preferable to have -Cl.

Further, as the compound A, a compound represented by the following general formula [Chemical formula 4] (the same as the above general formula [Chemical formula 2]) is particularly preferable.

[0016]

[Chemical 4]

In the above general formula [Chemical formula 4], R
The carbon number of ₁ is preferably 2 or more because molecules can be vertically aligned with respect to the substrate.

A preferred specific example of the compound A is a compound represented by the following general formula [Chemical formula 5] which is a compound of n = 2 in the general formula [Chemical formula 4].

[0019]

[Chemical 5]

The antistatic material of the present invention is adsorbed on a base material in a monomolecular layer or a structure close to a monomolecular layer, and causes no problem in the optical characteristics of the base material to be antistatic treated. , Optical parts, optical disks, optical recording media such as optical cards, and surface treatment of optical media. Of course, the antistatic treatment is not limited to optical materials such as optical recording media and optical media, and the color of colored materials such as bottles, cases, clothing, covers, and dishes can be completely controlled. It is useful in that it can be processed without discoloration.

There are no particular restrictions on the antistatic treatment of a substrate such as a substrate of an optical recording medium using the antistatic material of the present invention, but the hydrophilic substrate such as glass or plasma is used. , A polar group (hydrophilic group) on the surface by high energy treatment (hydrophilic group introduction treatment) such as UV-ozone or radiation treatment
A method of exposing the substrate into which the antistatic material is vaporized, or a method in which the antistatic material is dissolved in a non-aqueous solvent and the surface treatment is performed by immersing the substrate in the solution. The antistatic material can be adsorbed on the surface of the base material as a single molecule, but the latter method is preferable in consideration of process simplicity, safety, and the like.

As described above, by adsorbing a single molecule of the antistatic material on the surface of the base material, the carbazole rings are arranged on the base material in a highly oriented manner, exhibiting hopping conduction between the adjacent carbazole rings, and conducting. A layer is formed.

The above-mentioned dipping method will be further described. As the non-aqueous solvent, for example, n-hexadecane, bicyclohexyl, chloroform, carbon tetrachloride, or a mixed solvent thereof or a chlorosilane-based activator is used. Alcohol, acetone, etc. are desirable. Then, the antistatic material is dissolved in the non-aqueous solvent to obtain a solution, and then the substrate is immersed in the solution for 1 minute to 20 hours under a stream of dry nitrogen. After the completion of immersion, in order to wash the antistatic material that is not chemically bonded to the base material, subsequently, it is thoroughly washed in a solvent containing no antistatic material,
Further, it is washed with water and dried.

Further, it is possible to further improve the conductivity by polymerizing between adjacent carbazole rings. The above-mentioned polymerization method is not particularly limited, and various methods such as a method using an oxidizing agent or a method using radiation such as ultraviolet rays and electron beams can be used. Here, when polymerization is performed using radiation, the conductive polymer formed on the surface is in a neutral state, so it is desirable to perform a doping treatment with iodine or the like.

As the above-mentioned base material to be subjected to antistatic treatment, a base material made of an inorganic material such as glass or an inorganic oxide is desirable because a large amount of hydrophilic groups having active hydrogen are present on the surface, but it is made of a resin. The base material can also be used favorably by performing the hydrophilic group introduction treatment as described above.

Further, by forming the conductive polymer layer as described above, the antistatic property can be added.
You may coat an overcoat layer in order to add further function. At this time, the film thickness of the overcoat layer needs to be at a level that does not impair the antistatic property, and the coat film thickness is preferably 10 μm or less, more preferably 1 μm or less.
In the above overcoat layer, not only dust adhesion due to electrification but also liquid cross-linking force, water-based adhesive stains, oily adhesive stains, etc. may be considered as the cause of stains, so that the surface energy is low, that is, water repellency or oil repellency. Things are desirable. The water-repellent or oil-repellent overcoat layer is coated by diluting a silicone compound or a compound having a fluorofluoroalkyl group with a solvent, or a radiation-curable hard coat containing these compounds (for example, Shin-Etsu Chemical Co., Ltd.). Product name "KNS-5300, 5100"
Etc.) can be used. Also,
In order not to impair the antistatic property as much as possible, it is desirable that the overcoat layer has a monolayer level.

It is also possible to treat the antistatic-treated surface with a coating agent having properties such as water and oil at a level that does not impair the antistatic property.

Further, it is preferable that the surface of the substrate is hard-coated so that the pencil hardness thereof is H or more. In particular, when a base material made of resin is used as the base material, or when the substrate of the optical recording medium is used as the base material,
It is desirable to subject the surface to the above hard coat treatment in order to improve scratch resistance.

In the hard coat treatment, the surface of the substrate is a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, and the polyfunctional (meth) acrylate.
Coating and polymerization treatment with one or a mixture of two or more selected from the group consisting of monofunctional (meth) acrylates that are copolymerizable with acrylate and have a hydrophilic group in the molecule (hereinafter referred to as "coating material") It can be done by doing.

In the above hard coat treatment, the method of polymerization treatment is preferably radiation or heat curing.

The above-mentioned polyfunctional (meth) acrylate expresses the scratch resistance of the coating film and the surface protection effect of the substrate. Specifically, the trifunctional or higher functional (meth) acrylate, 2 Examples thereof include functional (meth) acrylates and other (meth) acrylates [oligomers], and when used, one kind or two or more kinds can be appropriately selected and used.

Trifunctional or higher functional (meth) acrylate: trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin tri (meth) acrylate, pentaerythritol tri ( (Meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and ethylene oxide and propylene oxide modified products thereof.

Bifunctional (meth) acrylate: 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, diethylene glycol di ( (Meth) acrylate, polyethylene glycol di (meth)
Acrylate, neopentyl glycol dimethacrylate, cyclopentadienyl alcohol di (meth) acrylate and the like. Other (meth) acrylates: polyester poly (meth) acrylate, epoxy (meth) acrylate, urethane poly (meth) acrylate, polysiloxane poly (meth) acrylate, polyamide poly (meth) acrylate and the like.

The monofunctional (meth) acrylate is added for the purpose of promoting the solubility of the antistatic copolymer, adjusting the viscosity, improving the adhesion to the substrate, etc. when actually coating the coating material. And specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypentyl (meth). ) Acrylate,
4-hydroxypentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethoxyethyl (meth) acrylate, N-hydroxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide and the like can be mentioned. The amount of the monofunctional (meth) acrylate used is preferably 0 to 40% by weight, and more preferably 0 to 10% by weight in consideration of scratch resistance and the like.

Further, as described above, since it is more preferable that the treatment with the antistatic material of the present invention has a hydrophilic group on the surface of the substrate, the above mixture has a hydrophilic group (--O) in the molecule.
It is desirable to contain the monofunctional (meth) acrylate having H, —COOH, —NH, —NH _2, etc.) as one component.

Further, when the above hard coat treatment is performed by radiation, it is unnecessary when curing by electron beams, γ rays, etc., but when it is performed by an ultraviolet curing type in consideration of practicality, the above coating material is used. It is necessary to add a photopolymerization initiator. Examples of the photopolymerization initiator include acetophenone-based photopolymerization initiators such as 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, diethoxyacetophenone, and 2-hydroxy-2-methylphenylpyropan-1-one; benzoin. Benzoin-based photopolymerization initiators such as methyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; thioxanthone-based light such as thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, and 2,4-diethylthioxanthone Examples thereof include a polymerization initiator, and when used, one kind or two or more kinds can be used. Further, the amount thereof is preferably 10 parts by weight or less with respect to 100 parts by weight of the polymerizable compound.

In order to obtain a desired film thickness, the coating material may be diluted by diluting the coating material with a solvent such as methanol, ethanol or isopropyl alcohol.

Next, the optical recording medium of the present invention will be described. The optical recording medium of the present invention is an optical recording medium in which a recording layer and a protective layer are sequentially formed on a substrate, and optical reproduction and recording / reproduction are performed on the entire surface or a predetermined portion of the surface of the optical recording medium. It is characterized in that it is subjected to antistatic treatment with the above antistatic material.

As the above-mentioned substrate, a known substrate which is usually used for an optical recording medium can be used without any particular limitation. Specifically, the same substrate as the above-mentioned substrate can be used. In the optical recording medium of the present invention, it is preferable that the hard coat treatment is performed before the antistatic treatment and the pencil hardness thereof is H or more.

As the recording layer and the protective layer, those usually used in optical recording media can be used without particular limitation.

The predetermined portion of the optical recording medium is usually on the pickup side (on the hard coat treated surface) or on the overcoat, and in the case of the optical recording medium in which the substrate is used by being inserted into a cartridge or the like. Alternatively, the cartridge may be used.

In a mode in which the optical recording medium of the present invention comprises the antistatic material, the antistatic material has the hydrophilic group on the surface bonded to the functional group on the surface of the optical recording medium. Examples thereof include a mode in which the carbazole rings are aligned, and a mode in which the carbazole rings are further polymerized.

To prepare the optical recording medium of the present invention, after the recording layer and the protective layer are sequentially formed on the substrate,
It can be easily obtained by performing the above-mentioned hard coat treatment, if necessary, and then subjecting the above-mentioned antistatic material to the antistatic treatment by the above-mentioned method.

The optical recording medium according to the present invention includes:
It is not particularly limited, and examples thereof include a magneto-optical disk, an optical card, a read-only optical disk, a write-once optical disk, and a mini disk.

[0045]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 First, a compound represented by the following structural formula [Chemical Formula 6] was added to dehydrated chloroform in an amount of 0.
A solution of the antistatic material was prepared by dissolving it at a concentration of 05 mol / liter. Next, the glass substrate ultrasonically cleaned in ethanol is added to the above solution in dry air by about 30 times.
It was immersed for a minute. After completion of the immersion, the glass substrate was pulled up, thoroughly washed in chloroform, washed with water, and then at 60 ° C. for 1 hour.
It was dried for a period of time to obtain a glass substrate whose surface was antistatic-treated.

[0047]

[Chemical 6]

Example 2 Pentaerythritol triacrylate / 2-hydroxy acrylate (weight ratio 1 /
0.5) 100 parts by weight of 6 parts by weight of "Irg.500" (manufactured by Ciba-Geigy Japan, trade name) was added to the hard coat coating so that the film thickness was about 5 μm on the polycarbonate substrate by spin coating. Was hardened with a high-pressure mercury lamp (irradiation dose 1600 mJ / cm ² ). Next, the obtained hard coat-treated substrate surface was manufactured by Oak Manufacturing Co., Ltd. under the trade name
Ozone treatment was performed for 2 minutes by "UV dry processor VUM-3073-B" to obtain a base material whose surface was hydrophilically treated. Using the obtained hydrophilic substrate, the same treatment as in Example 1 was carried out to obtain a polycarbonate substrate whose surface was antistatic treated.

Various evaluations were carried out on the antistatic treated substrates obtained in Examples 1 and 2. The evaluation results are shown in [Table 1].

[0050]

[Table 1]

The measurement conditions for each evaluation in [Table 1] are as follows. -Surface resistance applied voltage 500V (DC), ring electrode (JIS-69
11), environment: 23 ° C., 17% RH The value “after wiping EtOH” is the value after wiping the surface about 100 times with a cloth impregnated with EtOH. -Light transmittance Measurement wavelength: 830 nm, standard for% display; transmittance before each treatment

As is clear from the results shown in [Table 1],
By treating the surface of the base material with the antistatic material of the present invention, it was possible to realize conductivity expression without impairing the transparency of the base material.

Example 3 A recording layer (4 layers) was formed on a 3.5-inch polycarbonate substrate for a magneto-optical disk, and then the recording surface side was manufactured by Dainippon Ink and Chemicals, Inc. under the trade name "SD301". Is applied to form a protective layer, and a protective layer is formed on the pickup side, and 100 parts by weight of pentaerythritol triacrylate / 2-hydroxyacrylate (weight ratio 1 / 0.5) is Ir.
g. A hard coat paint containing 6 parts by weight of 500 (manufactured by Ciba-Geigy) was applied to a film thickness of about 5 μm by spin coating.
The coating was performed so as to have a thickness of m, hardened by a high pressure mercury lamp, and hard-coated (irradiation dose 1600 mJ / cm ² ). Next, the obtained hard-coated disk surface is
Ozone Co., Ltd., product name "UV dry processor VUM-3073-B" for 2 minutes ozone treatment,
A disk whose surface was hydrophilically treated was obtained. Using the obtained hydrophilically treated disc, the same treatment as in Example 1 was performed to obtain an antistatic-treated magneto-optical disc (the optical recording medium of the present invention).

No change in C / N and sensitivity was observed before and after the above treatment. The magneto-optical disk was used in an office environment for about 1 month, and then a dirt chamber test (ASTM D2741-68) was performed to measure the error rate, but the value did not change at all, but in the untreated disk The error rate has increased about 1000 times.

[0055]

INDUSTRIAL APPLICABILITY The antistatic material of the present invention is capable of imparting antistatic properties to a substrate without increasing the energy of the surface of the substrate, and is transparent and environment-dependent such as humidity-dependent on the substrate. It is possible to form an antistatic thin film layer having electron conductivity which is not received, and since it is chemically bonded to the substrate, it is unlikely to be removed from the substrate surface by solvent wiping or the like. Since the optical recording medium of the present invention comprises the above antistatic material, it is less likely to cause "dirt" and less likely to cause an error during use.

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Claims (6)

[Claims] 1. A carbazole ring and the following general formula:
An antistatic material comprising a compound having a functional group represented by in the molecule. [Chemical 1] 2. The antistatic material according to claim 1, wherein the compound is a compound represented by the following general formula [Chemical formula 2]. [Chemical 2] 3. An optical recording medium comprising a recording layer and a protective layer sequentially formed on a substrate for optically reproducing and recording / reproducing, wherein the entire surface or a predetermined portion of the surface of the optical recording medium is defined. An optical recording medium, which is antistatic-treated with the antistatic material described above. 4. The optical recording medium according to claim 3, wherein the substrate is a substrate made of an inorganic material. 5. The optical recording medium according to claim 3, wherein the substrate is a substrate made of resin. 6. A polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule, and a surface of the optical recording medium before the antistatic treatment, together with the polyfunctional (meth) acrylate. That the pencil hardness is H or more by coating with a mixture of one or more kinds selected from the group consisting of a monofunctional (meth) acrylate which is polymerizable and has a hydrophilic group in the molecule, and a polymerization treatment is performed. The optical recording medium according to claim 3, which is characterized in that.