JP2007059045A - Hard coating agent for optical disc, optical disc using the same, and production method thereof - Google Patents

Abstract

The present invention provides a hard coat agent and an optical disc suitable for an optical disc having excellent antistatic properties, wear resistance, and scratch resistance, and high productivity and storage reliability, and a method for producing the same.
A hard coat agent comprising a (meth) acrylate compound (A) containing a hydroxyl group in the molecule, a conductive metal oxide (B), a photopolymerization initiator (C), and a low-boiling alcohol solvent (D). The hard coat agent was applied to the laser light incident side surface of the optical disk by spin coating at room temperature at a rotation speed of 1000 to 7000 rpm, and then the ultraviolet coating was applied without passing through the process of removing the low boiling alcohol solvent (D). A method of manufacturing an optical disk to be cured.
[Selection figure] None

Description

  The present invention relates to a hard coat composition for an optical disc and a method for producing an optical disc using the same, and more specifically, a hard coat layer having high hardness and excellent antistatic properties, abrasion resistance, and scratch resistance. The present invention relates to an ultraviolet curable hard coat agent suitable for producing an optical disc having high productivity and storage reliability, and a method for producing a hard coat layer-added optical disc using the same.

  Optical disk recording media in practical use today include CD (compact disk), MO (magneto-optical disk), CD-R (write-once type), CD-RW (rewritable type) and the like. In these CDs, a recording film, a reflection film, and the like are formed on a 1.2 mm polycarbonate substrate, and an ultraviolet curable protective layer is provided for the purpose of protecting them from external factors.

  In recent years, a write-once DVD, a rewritable DVD, etc., in which a polycarbonate substrate is halved (0.6 mm) and two substrates are bonded, have been put to practical use in order to further improve the storage capacity. Each of these DVDs has a recording film, a reflective film and the like formed on a 0.6 mm polycarbonate substrate, and is provided with an ultraviolet curable protective layer or adhesive layer for the purpose of protection and adhesion.

  With the widespread use of OA equipment, the optical disc is widely used as a data storage means. As optical disks are widely spread, the handling method of optical disks and the environment in which optical disks are used have become more severe than ever. As a result, the laser light incident surface of the substrate is often damaged. Further, reproduction failures and recording errors due to such scratches have increased.

The polycarbonate substrate is a defective conductor of electricity. For this reason, the polycarbonate substrate is easily charged by friction. As a result, dust, dust, and the like easily adhere to the substrate surface during storage and use, and the dust, dust, and the like have caused regeneration failure.
Therefore, a method for protecting the substrate by providing a hard coat layer on the substrate surface on the laser beam incident surface side to improve wear resistance and scratch resistance has been studied. Furthermore, various studies have been made to provide a hard coat layer having antistatic performance.

  For example, such a hard coat layer includes a trifunctional or higher acrylate ester, a monofunctional ethylenically unsaturated group-containing compound, a photopolymerization initiator, and a conductive powder mainly composed of tin oxide or indium oxide. An optical disk material containing the above has been reported (see Patent Document 1). Specifically, in Examples of Patent Document 1, phosphorus-containing tin oxide having an average particle size of 0.2 μm or less (Example 1), antimony trioxide-containing tin oxide having an average particle size of 0.2 μm or less (Example 2) And antimony trioxide-containing indium oxide having an average particle size of 0.2 μm or less (Example 3).

  In addition, a hard coat agent containing colloidal silica and an ultraviolet curable acrylic resin and a hard coat solution containing a solvent mainly composed of propylene glycol monomethyl ether is coated, formed, and cured to a thickness of 1 to 5 μm. A hard coat layer has been reported (see Patent Document 2). And in patent document 2, by using propylene glycol monomethyl ether (boiling point: 120 degreeC), the rotation speed at the time of spin coat application | coating is made into 8000 rpm or more of high rotation from about 4000-5000 rpm, and it heat-drys. It is said that the hard coat layer can be cured without performing the process.

JP-A-4-172634 (2nd page, upper right column, 5th to 9th lines, Examples) JP 2004-272993 A (paragraphs 0007, 0011, 0021)

  Incidentally, as can be seen from the evaluation results of the surface resistivity, total light transmittance, suede value, and pencil hardness, the optical disk material in Patent Document 1 uses predetermined tin oxide and indium oxide, although it exhibits a predetermined performance. ing. In addition, these metal oxides tend to have insufficient stability.

  In addition, the average particle diameter of tin oxide and indium oxide used in the examples of the document is 0.2 μm or less. This means that it contains a particle size greater than 0.1 μm. According to the study by the present inventors, when the hard coat layer contains a large number of particles having a particle size larger than 0.1 μm, it tends to be difficult to obtain a hard coat layer having a stable and high total light transmittance. Is known.

  Moreover, in patent document 2, in order not to perform a heat drying process even when propylene glycol monomethyl ether (boiling point: 120 degreeC) is used, you have to perform spin coat application | coating by ultra high-speed rotation of 8000 rpm or more. When spin coating is applied at high speed, productivity may become unstable.

  Therefore, development of a hard coat layer having better scratch resistance, abrasion resistance, and antistatic properties is desired in the market. In addition, development of a technique for providing a hard coat layer on an optical disk with high productivity and low cost is also strongly demanded.

The present invention has been made to solve such a technical problem.
That is, the object of the present invention is that the surface of the optical disc on the laser beam incident side has better antistatic properties, wear resistance, and scratch resistance, and has high hardness, productivity, storage reliability, and low cost. An object of the present invention is to provide a hard coat agent for providing a hard coat layer that can be produced and a method for producing a hard coat layer-applied optical disc.
Another object of the present invention is to provide an optical disc manufactured by the above-described manufacturing method.

In order to solve such a technical problem, in the present invention, it is found that the above problem is solved by forming a hard coat agent having a specific composition on an optical disk using a specific method, The present invention has been completed.
That is, according to the present invention, the following (1) to (14) are provided.
(1) a (meth) acrylate compound (A) having a hydroxyl group in the molecule;
A conductive metal oxide (B) having a particle size measured by the BET method of 18 nm or less or an average particle size of 0.1 μm or less measured by a dynamic scattering method;
A photopolymerization initiator (C);
A low-boiling alcohol solvent (D), and a hard coating agent comprising:
(A) 30% by weight to 89% by weight, (B) 10% by weight to 30% by weight, and (C) 0.5% by weight to 20% by weight, based on the total amount of solids contained in the hard coat agent. A hard coat agent for an optical disc, characterized by comprising:
(2) The hard coat agent for an optical disc according to (1), wherein the low-boiling alcohol solvent (D) has a boiling point of 100 ° C. or lower.
(3) The hard coat agent for optical disks according to (1), wherein the conductive metal oxide (B) is zinc antimonate.
(4) The optical disk according to (1), wherein the content of the monofunctional ethylenically unsaturated group-containing compound is 4.5% by weight or less based on the total amount of solids contained in the hard coat agent. Hard coat agent.
(5) The hard coat agent for an optical disk according to (1), wherein the conductive metal oxide (B) is contained in an amount of 10 to 14% by weight based on the total amount of solids contained in the hard coat agent. .

(6) A method for producing an optical disk with a hard coat layer,
(Meth) acrylate compound (A) containing a hydroxyl group in the molecule, conductive metal oxide having a particle size measured by BET method of 18 nm or less or an average particle size measured by dynamic scattering method of 0.1 μm or less (B) A hard coating agent containing a photopolymerization initiator (C) and a low-boiling alcohol solvent (D) is applied to the laser light incident surface side surface of the optical disk by spin coating at a rotational speed of 1000 rpm to 7000 rpm at room temperature. Applying and curing with ultraviolet light,
A hard coat layer having a total light transmittance of 80% to 95% and a surface resistivity of 2 × 10 ¹² Ω / □ or less is provided on the laser light incident surface side surface of the optical disc. An optical disk manufacturing method.
(7) The blending ratio of the (meth) acrylate compound (A) containing a hydroxyl group in the molecule is 30% by weight to 95% by weight with respect to the total solid content of the hard coat agent. (6) The manufacturing method of the hard coat layer provision optical disk as described in (6).
(8) The content of the conductive metal oxide (B) with respect to the total solid content in the hard coat agent is 10% by weight to 30% by weight, according to (6) or (7) A method for producing an optical disk with a hard coat layer.
(9) The method for producing an optical disk with a hard coat layer according to any one of (6) to (8), wherein the conductive metal oxide (B) is zinc antimonate.
(10) The method for producing an optical disk with a hard coat layer according to any one of (6) to (9), wherein the low-boiling alcohol solvent (D) has a boiling point of 100 ° C. or lower.
(11) The method for producing an optical disk with a hard coat layer according to any one of (6) to (10), wherein the spin coating method is performed at a temperature of 15 ° C. to 35 ° C.
(12) The method of manufacturing an optical disc with a hard coat layer according to any one of (6) to (11), wherein the hard coat layer has a thickness of 1 μm to 5 μm.
(13) The content of the conductive metal oxide (B) with respect to the total amount of solids in the hard coat agent is 10% by weight to 14% by weight, and any one of (6) to (12) A method for producing an optical disk with a hard coat layer according to claim 1.

  (14) An optical disc produced by the method for producing an optical disc with a hard coat layer according to any one of (6) to (13).

  According to the present invention, there is provided a method for producing an optical disc having a hard coat layer that has excellent antistatic properties, abrasion resistance, scratch resistance, high productivity, high storage reliability, and can be produced at low cost, and thereby The resulting optical disc is provided. In addition, in the optical disk obtained by the method for manufacturing an optical disk of the present invention, reproduction defects and recording errors due to scratches on the laser light incident surface side are effectively suppressed. Furthermore, reproduction failure due to adhesion of dust or dust to the surface of the optical disk is effectively suppressed.

Hereinafter, the best mode (embodiment) for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.
In the present invention, the (meth) acrylate compound (A) having a hydroxyl group in the molecule, the particle size measured by the BET method is 18 nm or less, or the average particle size measured by the dynamic scattering method is 0.1 μm or less. A hard coating agent containing a conductive metal oxide (B), a photopolymerization initiator (C), and a low boiling point alcohol solvent (D) is used. And the said hard-coat agent is apply | coated by the spin coat method at the rotation speed 1000rpm-7000rpm, and is hardened | cured with an ultraviolet-ray. As a result, a good hard coat layer having a total light transmittance of 80 to 95% and a surface resistivity of 2 × 10 ¹² Ω / □ or less can be provided.

  Here, setting the total light transmittance of the hard coat layer to 80% to 95% means that information recorded on the optical disk can be reproduced satisfactorily. That is, by setting the total light transmittance of the hard coat layer to 80% to 95%, it becomes possible to satisfy the reproduction signal characteristics determined by the standards of CD, DVD, blue laser compatible optical disk, and the like. Conversely, in the optical disc having the hard coat layer of the present invention, the reproduction signal characteristics determined by the standards of CD, DVD, blue laser compatible optical disc, etc. are satisfied. It means that the range of the total light transmittance is controlled to 80% to 95%.

  In addition, it is expected that a blue laser will be used for recording / reproducing light in an optical disc that is required to have higher density in the future. Therefore, these optical discs are required to have high transmittance particularly at 405 nm, which is the wavelength of the blue laser. The transmittance value at a wavelength of 405 nm is preferably 90% or more, more preferably 95% or more.

  The transmittance of the hard coat layer basically indicates the transmittance of the hard coat layer alone. However, for example, a transmittance may be measured by forming a hard coat layer on a substrate having sufficient transparency with respect to the wavelength to be measured. As a specific example of such a measuring method, a test disk in which a hard coat layer is formed on a polycarbonate substrate is produced in the examples described later. The transmittance of this test disk is measured.

In addition, by setting the surface resistivity to 2 × 10 ¹² Ω / □ or less, the adhesion of dust, dust, and the like to the optical disk surface due to static electricity is effectively suppressed. If such adhesion of dust, dust and the like can be suppressed, regeneration failure and the like are easily suppressed. A known method (for example, a four-terminal method) can be used for measuring the surface resistivity.

In the present invention, first, by appropriately controlling the composition ratios (A) to (D), the total light transmittance is 80% to 95% and the surface resistivity is 2 × 10 ¹² Ω / □ or less. The hard coat layer can be realized.
Among the above (A) to (D), the major influence on the total light transmittance and surface resistivity of the hard coat layer is that the particle diameter measured by the BET method is 18 nm or less, or measured by the dynamic scattering method. The conductive metal oxide (B) having an average particle diameter of 0.1 μm or less.

From this viewpoint, in the present invention, the conductive metal oxide (B) having a very small particle size as described above is used. By using such a conductive metal oxide (B), the total light transmittance of the hard coat layer can be improved. And
1) Control of the particle size of the conductive metal oxide (B),
2) Type of conductive metal oxide (B) having the predetermined particle diameter (in the case of using a plurality of conductive metal oxides, these composition ratios),
3) Content of conductive metal oxide (B),
By combining and controlling these three elements, a hard coat layer having a total light transmittance of 80% to 95% and a surface resistivity of 2 × 10 ¹² Ω / □ or less can be easily realized.

  In addition, by using the (meth) acrylate compound (A) having a hydroxyl group in the molecule, the dispersion of the conductive metal oxide (B) is easily stabilized. As a result, it becomes easy to increase the transmittance of the hard coat layer during coating. As described above, the combination of the (meth) acrylate compound (A) having a hydroxyl group in the molecule and the predetermined conductive metal oxide (B) can satisfactorily control the total light transmittance and the surface resistivity. .

Hereinafter, each element used for the hard coat agent of the present invention will be described.
The (meth) acrylate compound (A) having a hydroxyl group in the molecule contributes particularly to the dispersion stability and curability of the conductive metal oxide. In the present invention, examples of the (meth) acrylate compound (A) having a hydroxyl group in the molecule include epoxy (meth) acrylate and hydroxyl group-containing (meth) acrylate.

Any epoxy (meth) acrylate may be used as long as it is obtained by reacting a glycidyl ether type epoxy compound with (meth) acrylic acid.
Examples of the glycidyl ether type epoxy compound include bisphenol A, diglycidyl ether of its alkylene oxide adduct, bisphenol F, diglycidyl ether of its alkylene oxide adduct, hydrogenated bisphenol A, or dioxide of its alkylene oxide adduct. Glycidyl ether, hydrogenated bisphenol F or its alkylene oxide adduct diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, Cyclohexane dimethylol diglycidyl ether, polypropylene glycol diglycidyl ether And the like can be given.

  The epoxy (meth) acrylate is, for example, 0.9 equivalent to 1.5 equivalents, preferably 0.95 equivalents to 1.1 equivalents of (meth) acrylic acid with respect to 1 equivalent of the epoxy group of the epoxy resin. It can also be obtained by reacting at a ratio. In this reaction, the reaction temperature is preferably 80 ° C to 120 ° C. The reaction time is preferably about 10 to 35 hours.

  In order to accelerate the reaction, it is also preferable to use a catalyst such as triphenylphosphine, triethanolamine, tetraethylammonium chloride, and the like. In addition, a polymerization inhibitor (for example, paramethoxyphenol, methylhydroquinone, etc.) can be used to prevent polymerization during the reaction. In the resin composition of the present invention, one or more epoxy (meth) acrylates can be mixed and used at an arbitrary ratio. The molecular weight of the epoxy (meth) acrylate is preferably 200 to 10,000.

  Next, specific examples of the hydroxyl group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , Dipropylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, caprolactone acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, dimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) ) Acrylate, pentaerythritol alkylene oxide adduct tri (meth) acrylate, dimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate Relate can dipentaerythritol penta (meth) acrylate.

  More preferable examples include pentaerythritol tri (meth) acrylate, dimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and the like. These hydroxyl group-containing (meth) acrylates can be used alone or in combination of two or more in any proportion.

  The content of the (meth) acrylate compound (A) having a hydroxyl group in the molecule with respect to the total solid content of the hard coat agent in the present invention is usually 30% to 89% by weight, preferably 40% to 85%. % By weight.

  Next, in the present invention, a conductive metal oxide (B) is used. By using the conductive metal oxide (B), conductivity can be imparted to the hard coat layer. As a result, it is possible to suppress the adsorption of dust and dust to the hard coat layer due to static electricity. The conductive metal oxide (B) only needs to be capable of imparting the above function to the hard coat layer. More specifically, a metal oxide having a volume resistivity of 1 kΩ · cm to 10 kΩ · cm when measured with a four-point probe resistivity measuring device (trade name: Lorester, manufactured by Mitsubishi Chemical Corporation) is used. That's fine.

  Specific examples of the conductive metal oxide (B) include antimony-doped tin oxide, tin-doped indium oxide, and zinc antimonate. Zinc antimonate is preferable. These are preferably used as organosols dispersed in an organic solvent. Further, the conductive metal oxide (B) in powder form can be used by dispersing in a resin.

  As for the particle diameter of the conductive metal oxide (B), the particle diameter by the BET method calculated by the gas phase adsorption method in the particle state is 18 nm or less. Alternatively, the conductive metal oxide (B) has an average particle size of 0.1 μm or less as measured by a dynamic scattering method measured in a sol state dispersed in a solvent. By setting the conductive metal oxide (B) within the range of the particle diameter, smoothness and transparency of the coated surface can be sufficiently obtained. In addition, in order to improve the antistatic performance, when the content of the conductive metal oxide (B) in the hard coat layer is increased (for example, the conductive metal oxide (B in the solid content of the hard coat agent) ), The transparency is easy to ensure.

On the other hand, the lower limit value of the particle size of the conductive metal oxide (B) is actually as follows. That is, the particle diameter measured by the BET method is 5 nm or more. On the other hand, the average particle diameter measured by the dynamic scattering method is 5 nm or more.
These conductive metal oxides (B) can be used alone or in combination of two or more in any proportion.

  Specific examples of the conductive metal oxide (B) suitable for the present invention are listed below. Examples of antimony-doped tin oxide (ATO) include FSS-10M and SNS-10M (both manufactured by Ishihara Sangyo Co., Ltd.). Further, examples of indium tin oxide (ITO) include an ITO dispersion manufactured by CI Kasei Co., Ltd. Furthermore, examples of zinc antimonate include Celnax CX-Z600M-3, CX-Z600M-3F, and CX-Z210IP-F2 (all manufactured by Nissan Chemical Industries, Ltd.). These materials are readily available from the market.

  The content of the conductive metal oxide (B) in the total solid content of the hard coat agent in the present invention is usually 10% by weight to 30% by weight, preferably 10% by weight to 25% by weight. In particular, when a blue laser is used as the recording / reproducing light, 10% by weight to 14% by weight is particularly preferable.

  Incidentally, the particle diameter by the BET method is calculated by a gas phase adsorption method in a powder state of a conductive metal oxide. Moreover, the average particle diameter by a dynamic scattering method can be measured with the N4 apparatus (or equivalent apparatus) by Coulter in the sol state of the conductive metal oxide. The property of the conductive metal oxide in the case of measurement by the BET method is usually powder. On the other hand, the property of the conductive metal oxide in the case of measurement by the dynamic scattering method is usually a liquid such as a sol.

  When the conductive metal oxide (B) is mixed or dispersed in the hard coat agent, a dispersant may be used to stabilize the dispersion state of the conductive metal oxide (B). Examples of the dispersant include cationic, anionic, nonionic or double-sided surfactants. Preference is given to alkylamine surfactants. For example, Solsperse 20000 (trade name, manufactured by Zenega Corp., PO, EO modified product of alkylamine) or TAMNO-15 (trade name, manufactured by Nikko Chemical Co., Ltd., EO modified product of alkylamine). The amount of the dispersant added is usually 0.5% to 30% by weight, preferably 1% to 20% by weight, based on the conductive metal oxide used.

As the photopolymerization initiator (C) in the present invention, any photopolymerization initiator (C) may be used as long as it has a function of initiating polymerization upon irradiation with ultraviolet rays.
Specific examples of the photopolymerization initiator (C) include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropane- 1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one or 2-methyl- [4- (methylthio) phenyl] -2- Morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, isopropyl Thioxanthone, 2,4,6-trimethylbenzoyldiphosphine oxide or bis (2,6-dimethyl) Kishibenzoiru) -2,4,4-trimethyl pentyl phosphine oxide and the like.

  These photopolymerization initiators can be used alone or in admixture of two or more. The content of the photopolymerization initiator (C) with respect to the total solid content of the hard coating agent is usually 0.5% by weight to 20% by weight, preferably 1% by weight to 15% by weight.

  Further, it can be used in combination with photopolymerization initiation assistants such as amines. Specific examples of amines include 2-dimethylaminoethyl benzoate, dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester or p-dimethylaminobenzoic acid isoamyl ester. The content of the photopolymerization initiation assistant in the total solid content of the hard coat agent is usually 0.005 wt% to 5 wt%, preferably 0.01 wt% to 3 wt%.

  The hard coating agent contains a low boiling alcohol solvent (D). By using the low boiling point alcohol solvent (D), it is not necessary to perform heat drying after applying the hard coating agent. That is, the hard coat agent can be applied and cured at room temperature. As a result, the phenomenon in which the surface coated with the hard coating agent is attacked by the predetermined (meth) acrylate compound (A) due to heat drying is suppressed. In addition, a drying device is not necessary, and the process can be shortened. Further, the production cost can be reduced.

  As the low boiling alcohol solvent (D), those having a boiling point of 100 ° C. or less are preferable. On the other hand, the boiling point of the low-boiling alcohol solvent (D) is practically usually 65 ° C. or higher. Specific examples of the low boiling alcohol solvent (D) include methyl alcohol (65 ° C.), ethyl alcohol (78 ° C.), isopropyl alcohol (83 ° C.), n-propyl alcohol (97 ° C.), t-butyl alcohol (83 ° C. And the like. These low boiling alcohol solvents (D) can be used alone or in combination of two or more. The content of the low-boiling alcohol solvent (D) in the hard coat agent is usually 20% by weight to 70% by weight, preferably 30% by weight to 65% by weight.

  In addition, when the organosol of the conductive metal oxide (B) is used and the low boiling alcohol solvent (D) is used as the medium, the content of the low boiling alcohol solvent (D) in the hard coating agent is as follows. You can decide as follows. That is, the content of the low-boiling alcohol solvent (D) is appropriately determined in consideration of the content in the sol.

  In the present invention, a low-boiling alcohol solvent (D) is used, but this does not exclude the use of a high-boiling solvent (for example, a solvent having a boiling point higher than 100 ° C.). This is because the low-boiling alcohol solvent (D) is used because it is not heated and dried at room temperature or higher. Therefore, a high-boiling solvent may be contained in the hard coat agent as long as a hard coat layer having good characteristics can be obtained without heating and drying.

  Specifically, when a high boiling point solvent is contained in the hard coat agent, the content of the high boiling point solvent is usually 15% by weight or less. When the high boiling point solvent is excessively contained, it is necessary to remove the solvent through a drying step after spin coating as described above. This is because if the high-boiling point solvent is not sufficiently removed, the cured film is likely to be whitened or the hardness is lowered. Furthermore, cracks and the like are likely to occur in the cured film. In addition, the uniformity and productivity of the hard coat layer may be inferior. And it becomes easy to peel a hard-coat layer from an optical disk. This peeling phenomenon seems to be affected by the type, boiling point, content, etc. of the solvent used.

However, when an alcohol solvent is used as the high-boiling solvent, the upper limit of the high-boiling solvent can be about 20% by weight because it is a common solvent with the low-boiling alcohol solvent (D).
When the low-boiling alcohol solvent (D) is used, there is a low risk of residual solvent. In addition, the characteristics of the hard coat layer can be sufficiently expressed even when irradiated with ultraviolet rays without a drying step. This phenomenon is more markedly exhibited when an alcohol solvent having a boiling point of 100 ° C. or lower is used.

  In the present invention, a (meth) acrylate compound other than the (meth) acrylate compound (A) having a hydroxyl group in the molecule can be arbitrarily used as necessary. Examples of such (meth) acrylate compounds include (meth) acrylate monomers and (meth) acrylate oligomers.

  (Meth) acrylate monomers can be classified into monofunctional monomers having one (meth) acrylate group in the molecule and polyfunctional monomers having two or more (meth) acrylate groups in the molecule. Specific examples of monofunctional monomers having one (meth) acrylate group in the molecule include tricyclodecane (meth) acrylate, dicyclopentadieneoxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and isobornyl. (Meth) acrylate, adamantyl (meth) acrylate, phenyloxyethyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, morpholine (meth) acrylate, phenylglycidyl (meth) acrylate, 2-hydroxy Examples include ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and ethyl carbitol (meth) acrylate.

  Specific examples of polyfunctional monomers having two or more (meth) acrylate groups in the molecule include neopentyl glycol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, hydroxypivalaldehyde-modified tri Methylolpropane di (meth) acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dicyclopentanyl di (meth) Acrylate, 1,6-hexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, trimethylo Propane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dimethylolpropane tetra (meth) acrylate, ethylene oxide modified pentaerythritol tetra (meth) acrylate, tris [( (Meth) acryloxyethyl] isocyanurate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, ethylene oxide-modified dipentaerythritol hexa (meth) acrylate, and the like.

  Preferable examples of the (meth) acrylate oligomer include urethane (meth) acrylate having a molecular weight of 400 to 10,000. A urethane (meth) acrylate having a molecular weight of 400 to 10,000 is obtained by appropriately reacting the following polyhydric alcohol, organic polyisocyanate, and hydroxy (meth) acrylate compound.

  Examples of the polyhydric alcohol include neopentyl glycol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, Tricyclodecane dimethylol, bis- [hydroxymethyl] -cyclohexane, etc .; these polyhydric alcohols and polybasic acids (for example, succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydroanhydride) Polyester polyols obtained by reaction with phthalic acid, etc .; caprolactone alcohols obtained by reaction of the polyhydric alcohols with ε-caprolactone; polycarbonate polyols (for example, 1,6-hexanediol and diesters) Eniruka - polycarbonate diol obtained by reacting Boneto etc.), polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyether polyols, such as ethylene oxide modified bisphenol A.

  Examples of the organic polyisocyanate include isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and dicyclopentanyl isocyanate.

  Examples of the hydroxy (meth) acrylate compound include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, dimethylol cyclohexyl mono (meth) acrylate, hydroxycaprolactone (meth) acrylate, and the like. It is done.

  These (meth) acrylate compounds may be used alone or in combination of two or more in any proportion. When the (meth) acrylate is used, the content ratio of the (meth) acrylate compound in the solid content of the hard coat agent is determined in consideration of the hardness of the hard coat layer. For example, the content ratio of the monofunctional (meth) acrylate compound is usually 0 to 4.5% by weight.

  Moreover, it is preferable that a hard-coat agent contains the modifier of the hard-coat layer surface further. By using such a modifier, it becomes easy to wipe even when fingerprint oil adheres to the surface of the hard coat layer.

  Examples of the modifier include silicon-based or fluorine-based leveling agents and surface lubricants. Preferable examples include a silicon-based leveling agent and a fluorine-based surface modifier.

  Examples of the silicon-based leveling agent include BYK-307, BYK-322, BYK-323, BYK-331, BYK-333, BYK-UV3500, BYK-UV3510, BYK-UV3530, and BYK-UV3570 (trade names BYK-Chemie Corporation). Manufactured poly (di) methylsiloxane compound). Moreover, as a fluorine-type surface modifier, for example, Modiper F-100, F-110, F-200, F-202, F-2020, F-220, F-500, F-600 And fluorine-containing block copolymer).

  When a modifier is used, the additive amount of the modifier is usually 1% to 20% by weight, preferably 2% to 10% by weight, based on the hard coat agent.

  Furthermore, in the present invention, if necessary, a polymer (for example, a polymer such as polyester, polycarbonate, polyacryl, polyurethane, and polyvinyl resin), an organic solvent, a polymerization inhibitor, a light stabilizer, Various additives known per se such as antioxidants, antistatic agents and fillers can be used in combination.

  The hard coat agent can be obtained by mixing and dissolving the above-described components at 20 ° C. to 60 ° C. by a conventional method. Further, if necessary, the particle size can be made uniform by performing a filtration treatment. Further, impurities (impurities) can be removed by filtration.

Next, a method for forming a hard coat layer on an optical disk using a hard coat agent will be described.
As the optical disk on which the hard coat layer is formed in the present invention, any commercially available optical disk can be used, and is not particularly limited. That is, an optical disc refers to an information recording medium that has a recording / reproducing functional layer and performs at least one of recording, erasing, and reproducing information using light. Here, a laser beam is usually used as the light.

  The recording / playback functional layer is a rewritable medium (ROM medium), a rewritable medium (write once medium) that can be recorded only once, or a rewritable medium that can be repeatedly recorded and erased (write once medium). Depending on the case of a rewritable medium), a layer structure corresponding to each purpose can be adopted. The recording / reproducing functional layer can be divided into a substrate surface incident type and a film surface incident type depending on the incident direction of the recording / reproducing laser beam.

A specific example of the recording / reproducing functional layer will be described below.
(Example of read-only media)
In a read-only medium, the recording / reproducing functional layer is usually obtained by forming a reflective layer and a protective layer on a substrate. As a material for the reflective layer, a metal or an alloy such as Al, Ag, or Au is usually used. As a material for the protective layer, an ultraviolet curable resin is usually used. Moreover, you may use plate-shaped members, such as resin (for example, polycarbonate) and a metal, as a protective layer.

The recording / reproducing functional layer is usually formed as follows. That is, the reflective layer is formed by forming an Al, Ag, Au reflective layer on the substrate by sputtering. Then, a protective layer is formed by applying and curing an ultraviolet curable resin on the reflective layer. Moreover, when using plate-shaped members, such as resin (for example, polycarbonate) and a metal, for a protective layer, what is necessary is just to adhere | attach these members to a reflective layer using an adhesive agent.
Here, when the light incident surface is on the substrate side, a hard coat layer is provided on the substrate. On the other hand, when the light incident surface is on the protective layer side, a hard coat layer is provided on the protective layer.

(Example 1 of write-once medium)
In a write-once medium and a film surface incidence type medium, the recording / reproducing functional layer is usually obtained by providing a reflective layer, a recording layer, and a protective layer in this order on a substrate. Here, a buffer layer formed of an inorganic material (for example, ZnS / SiO ₂ ) may be provided between the recording layer and the protective layer.

On the other hand, in a write-once medium and a substrate surface incident type medium, the recording / reproducing functional layer is usually obtained by providing a recording layer, a reflective layer, and a protective layer in this order on a substrate.
Here, in the substrate surface incident type medium, a hard coat layer is provided on the substrate. On the other hand, in the film surface incident type medium, a hard coat layer is provided on the protective layer.

  As a material for the reflective layer, a metal or an alloy such as Al, Ag, or Au is usually used. As a material for the protective layer, an ultraviolet curable resin is usually used. Moreover, you may use plate-shaped members, such as resin (for example, polycarbonate) and a metal, as a protective layer. The method for forming the reflective layer and the protective layer may be the same as that for the read-only medium. When a plate-like member such as resin (for example, polycarbonate) or metal is used for the protective layer, these members can be bonded to the recording layer, buffer layer, or reflective layer using an adhesive. Good.

  As a material for the recording layer in the write-once medium, an organic dye is usually used. Examples of such organic dyes include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes, squarilium dyes, etc.), anthraquinone dyes, azurenium dyes, Examples thereof include metal azo dyes and metal-containing indoaniline dyes. In particular, metal-containing azo dyes are preferable because they are excellent in durability and light resistance.

  When forming a recording layer with an organic dye, the recording layer is usually formed by a coating method such as spin coating, spray coating, dip coating, or roll coating using a solution in which the organic dye is dissolved in an appropriate solvent. In this case, the solvent includes ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolve solvents such as methyl cellosolve and ethyl cellosolve, and perfluorocarbons such as tetrofluoropropanol and octafluoropentanol. Hydroxyethyl solvents such as alkyl alcohol solvents, methyl lactate and methyl isobutyrate are preferably used.

  The thickness of the recording layer is not particularly limited because a suitable film thickness varies depending on the recording method or the like, but is usually 5 nm or more, preferably 10 nm or more, and particularly preferably 20 nm or more in order to obtain a sufficient degree of modulation. It is. However, since it is necessary to transmit light, it is usually 3 μm or less, preferably 1 μm or less, more preferably 200 nm or less.

(Example 2 of write-once medium)
In another specific example of the write-once medium and the film surface incidence type medium, the recording / reproducing functional layer is usually provided with a reflective layer, a dielectric layer, a recording layer, a dielectric layer, and a protective layer on a substrate. It is obtained by providing in order. On the other hand, in another specific example of the write-once medium and the substrate surface incident type medium, the recording / reproducing functional layer is usually provided on the substrate with a dielectric layer, a recording layer, a dielectric layer, a reflective layer, and a protective layer. Are provided in this order.

  Here, in the substrate surface incident type medium, a hard coat layer is provided on the substrate. On the other hand, in the film surface incident type medium, a hard coat layer is provided on the protective layer. As a material for the reflective layer, a metal or an alloy such as Al, Ag, or Au is usually used. As a material for the protective layer, an ultraviolet curable resin is usually used. Moreover, you may use plate-shaped members, such as resin (for example, polycarbonate) and a metal, as a protective layer. The method for forming the reflective layer and the protective layer may be the same as that for the read-only medium.

As a material for the dielectric layer, an inorganic material (typically, ZnS / SiO ₂ ) is usually used. The dielectric layer is usually formed by sputtering.

  The recording layer is usually made of an inorganic material (for example, a chalcogen alloy such as GeTe or GeSbTe). The recording layer is usually formed by sputtering. The film thickness of the recording layer is usually about 1 nm to 50 nm.

(Example 1 of rewritable medium)
In a rewritable medium and a film surface incidence type medium, the recording / reproducing functional layer is usually formed by providing a reflective layer, a dielectric layer, a recording layer, a dielectric layer, and a protective layer in this order on a substrate. can get. On the other hand, in a rewritable medium and a substrate surface incident type medium, the recording / reproducing functional layer is usually provided with a dielectric layer, a recording layer, a dielectric layer, a reflective layer, and a protective layer in this order on the substrate. Can be obtained.
Here, in the substrate surface incident type medium, a hard coat layer is provided on the substrate. On the other hand, in the film surface incident type medium, a hard coat layer is provided on the protective layer.

  The reflective layer, the dielectric layer, the recording layer, and the protective layer may be the same as those in the write-once medium example 2. However, the recording layer needs to be made of a material capable of reversible recording / erasing. Examples of such materials include SbTe, GeTe, GeSbTe, InSbTe, AgSbTe, AgInSbTe, GeSb, GeSbSn, InGeSbTe, and InGeSbSnTe. Among these, it is preferable to use a composition containing Sb as a main component in the recording layer in order to increase the crystallization speed.

(Example 2 of rewritable medium)
Another specific example of the rewritable medium is a magneto-optical recording medium (MO disk).

(Common subject matter)
As the substrate used for the recording / reproducing functional layer, the following are usually used.
That is, the substrate can be made of plastic, metal, glass or the like having appropriate processability and rigidity. In the substrate surface incident type optical recording medium, the substrate needs to be transparent to the incident laser beam. In the film surface incident type optical recording medium, since the laser beam does not normally pass through the substrate, the substrate does not need to be transparent to the laser beam.

When the substrate is made of metal or glass, it is necessary to provide a light or thermosetting thin resin layer on the surface and to form a groove there. In this respect, it is preferable in terms of manufacturing to use a plastic material and to form the shape of the substrate (particularly a disc shape) and the guide groove on the surface at once by injection molding.
As the plastic material that can be injection-molded, polycarbonate resin, polyolefin resin, acrylic resin, epoxy resin, and the like conventionally used in CDs and DVDs can be used. The thickness of the substrate is preferably about 0.5 mm to 1.2 mm.

Usually, a guide groove for tracking is formed on the substrate.
The track pitch varies depending on the wavelength of the laser beam used for recording / reproducing on the optical recording medium. Specifically, in a CD-based optical recording medium, the track pitch is usually 1.5 μm to 1.6 μm. In a DVD optical recording medium, the track pitch is usually 0.7 μm to 0.8 μm. In the optical recording medium for blue laser, the track pitch is usually 0.2 μm to 0.5 μm. On the other hand, the depth of the groove also varies depending on the wavelength of the laser beam used for recording / reproducing of the optical recording medium. Specifically, in a CD-based optical recording medium, the groove depth is usually 10 nm to 300 nm. In a DVD optical recording medium, the groove depth is usually 10 nm to 200 nm. In the optical recording medium for blue laser, the groove depth is usually 10 nm to 200 nm.

(Specific examples of optical disks currently in practical use)
Specific examples of optical disks that are currently in practical use include CD (compact disk) with a polycarbonate substrate of 1.2 mm, MO (magneto-optical disk), CD-R (write-once type), CD-RW (rewritable type), etc. There is. In recent years, in order to improve the storage capacity, there are a write-once DVD and a rewritable DVD in which the thickness of polycarbonate is halved (0.6 mm) and two substrates are bonded.

In the present invention, a hard coat layer having a predetermined composition of the present invention is applied and cured on the laser light incident side surface of an optical disk at room temperature to obtain a hard coat layer. Specifically, the hard coat agent is applied by a spin coat method at a rotation speed of 1000 rpm to 7000 rpm and cured by ultraviolet rays to obtain a hard coat layer.
Here, the room temperature refers to a temperature range in which a person can work without feeling uncomfortable. Specifically, the temperature range of 15 degreeC-35 degreeC can be mentioned. This also means that heat drying is not required after coating by spin coating.

Specific examples of application by spin coating and curing by ultraviolet rays will be described below.
First, after adjusting the viscosity with the low boiling point alcohol solvent (D), if necessary, a hard coating agent having a predetermined composition is applied to the laser irradiation surface of the optical disk by a known spin coating method. At this time, the hard coat layer is applied so as to have a thickness of 1 to 10 μm at the time of curing. Further, the spin coating is performed at room temperature under the condition of a rotational speed of 1000 rpm to 7000 rpm. However, from the viewpoint of reducing the burden on the apparatus, the rotational speed is preferably 1000 rpm to 5000 rpm, more preferably 1000 rpm to 4000 rpm.

After application, the hard coat layer (hardened product of hard coat agent) is obtained by irradiating with light such as ultraviolet rays while keeping the temperature at room temperature (that is, without drying at a temperature higher than room temperature). Can do. The light source at the time of curing is not particularly limited as long as it is a lamp capable of irradiating ultraviolet to near ultraviolet rays. As the light source, for example, a low-pressure, high-pressure or ultra-high-pressure mercury lamp, metal halide lamp, (pulse) xenon lamp, or electrodeless lamp can be used. Irradiation energy - is usually ^{100mJ / cm 2 ~1000mJ / cm 2} . In the above example, ultraviolet irradiation is performed after application by spin coating, but ultraviolet irradiation may be performed simultaneously with application by spin coating. For example, the above method is effective when high-precision film thickness control is required.

The hard coat layer thus obtained has a (meth) acrylate resin having a hydroxyl group in the molecule, a particle size measured by the BET method of 18 nm or less or an average particle size measured by the dynamic scattering method Contains a conductive oxide of 0.1 μm or less. The total light transmittance of the hard coat layer is 80% to 95%, and the surface resistivity is 2 × 10 ¹² Ω / □ or less.

  As described above, the present invention is obtained by a method for producing an optical disc having excellent antistatic properties, abrasion resistance, scratch resistance, high hardness and high storage reliability, and excellent productivity. An optical disc can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
(Preparation of test disc)
Each hard coat agent shown in Table 1 and Table 2 to be described later is applied on a transparent optical disk substrate (polycarbonate) by a spin coater (manufactured by Global Machinery, rotation speed: 3000 rpm to 4000 rpm, time: 1.5 to 3 seconds). It was applied so that the film thickness at the time of drying was 1 μm to 5 μm (at the end of application, the hard coat agent was in a dry state). Next, a test disk was prepared by curing the applied hard coat agent with an ultraviolet irradiation device (Fusion HP-6, UV lamp: D bulb) under the condition of an integrated light quantity of 400 mJ / cm ² .

The following items were evaluated using the test disks described above.
(Stability of hard coating agent)
50 g of each hard coat agent shown in Table 1 and Table 2 described later was put in a 50 ml brown sample bottle, covered, and left in a constant temperature dryer at 40 ° C. for 1 month. Thereafter, the state of the hard coating agent in each brown sample bottle was visually observed, and the stability of the hard coating agent was evaluated according to the following criteria.
○ (OK): No aggregation or sedimentation in the zinc antimonate sol in the hard coating agent × (NG): Aggregation or sedimentation was confirmed in the zinc antimonate sol

(Abrasion resistance (Δhaze))
Inside the disc on the hard coat layer surface of the test disc prepared in advance using an abrasion tester compliant with JIS K7204 (made by Toyo Seiki Seisakusho Co., Ltd., wear wheel: CS-10F, load: 250 gf) The circumference was worn 50 times. Then, the haze was measured using the haze meter (apparatus: Tokyo Denshoku TC-HIIIDPK) based on JIS K7136. And the value of haze before and behind abrasion was compared. The amount of change in haze value before and after the wear was defined as Δhaze (unit:%). Δhaze is preferably 10% or less.

(Ease of wiping fingerprints)
After attaching a fingerprint to the hard coat layer surface of the test disc prepared in advance, the fingerprint oil was wiped off with Kimwipe S-200 (manufactured by Crecia Co., Ltd.), and the ease of wiping off the fingerprint was evaluated according to the following criteria.
○ (OK): Fingerprint was visually removed by wiping within 5 reciprocations of Kimwipe S-200. X (NG): Fingerprint oil remained visually even after wiping after 5 reciprocations of Kimwipe S-200.

(Total light transmittance)
Using a haze meter according to JIS K7105 (manufactured by Tokyo Denshoku Co., Ltd., TC-HIIIDPK), the total light transmittance at three points on the hard coat layer surface of the test disk prepared in advance was measured. The average value of the transmittance was defined as the final total light transmittance (unit:%). The larger the value, the higher the light transmittance.

(Transmittance at a wavelength of 405 nm)
Using a spectrophotometer (U-3310, manufactured by Hitachi, Ltd.), the transmittance at 405 nm was measured at three points on a test disk coated with a pre-adjusted hard coat agent in comparison with an uncoated transparent optical disk substrate. The average value of the transmittance at these three points was defined as the final transmittance at 405 nm (unit:%). The larger the value, the higher the light transmittance.

(Surface resistivity)
A test disk prepared in advance was left in an environment of 25 ° C. and 65% for one day. Then, using a surface resistance measuring instrument (HIRESTA-IP manufactured by Mitsubishi Chemical Corporation, applied voltage: 250 V, time: 10 seconds) in accordance with JIS K6911, the surface resistivity of the five points on the hard coat layer surface was measured. The average value of these five points was used as the final surface resistivity (unit: Ω / □). The smaller the value, the higher the antistatic performance.

(Half life)
The half-life is the time required for the initial charging voltage to decay to a half value. The half-life test method is as follows.
A test disk prepared in advance was left in an environment of 25 ° C. and 65% for one day. After that, using a half-life measuring device in accordance with JIS L1094 (HO110, manufactured by Shishido electrostatic Co., Ltd., applied voltage: 10 kV, voltage application time: 60 seconds), the time change of the charging voltage at three points on the hard coat layer surface was changed. The half life was measured for the above three points. Further, the half-lives obtained at the above three points were averaged to obtain the final half-life (unit: seconds (sec)). This averaged half-life is preferably within 10 seconds.

(Adhesion to substrate)
In accordance with JIS K5400, 11 cuts were made on the surface of the hard coat layer of the test disk prepared in advance at intervals of 1 mm with a cutter knife to make 100 grids. Then, after the cellophane tape was brought into close contact with the surface, when it was peeled off at once, the number of cells remaining without peeling was displayed (unit: number / 100). The adhesion is preferably 90/100 or more.

  Among the above evaluation items, “stability of hard coat agent” and “easy to wipe off fingerprints” are evaluation items based on the viewpoint of obtaining a hard coat layer with improved productivity and usability. In addition, “total light transmittance”, “adhesion to substrate”, “surface resistivity”, “half-life”, and “abrasion resistance” are evaluation items based on the viewpoint of obtaining a practically usable hard coat layer. It is.

(Example 1 to Example 6)
Table 1 shows each component composition (parts by weight and parts by weight) of the ultraviolet curable hard coat agent used in each of (Example 1 to Example 6).
The hard coat agent shown in Table 1 was prepared by blending each component by a conventional method.
In Examples 1 to 6, as the conductive metal oxide (B), an organosol of zinc antimonate having an average primary particle size of 0.1 μm or less by a dynamic scattering method was used. The zinc antimonate organosol contains zinc antimonate and a low boiling alcohol solvent.

In addition, the symbol of each composition shown in Table 1 is as follows.
(A) (A) component ((meth) acrylate compound (A) having a hydroxyl group in the molecule)
PET-30: pentaerythritol triacrylate, manufactured by Nippon Kayaku Co., Ltd. R-167: 1,6-hexanediol epoxy acrylate, manufactured by Nippon Kayaku Co., Ltd. R-115: bisphenol A type epoxy acrylate, Nippon Kayaku Made by Co., Ltd.

(B) Component (B) (conductive metal oxide (B) having an average particle size of 0.1 μm or less)
Zinc antimonate: an organosol of zinc antimonate having an average primary particle size of 0.1 μm or less by a dynamic scattering method

(C) (C) component (photoinitiator (C))
IRG-184: 1-hydroxycyclohexyl phenyl ketone, manufactured by Ciba Specialty Chemicals Co., Ltd. IRG-907: 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, Ciba Specialty Made by Chemical Corporation

(D) Other monomers PET-40: Pentaerythritol tetraacrylate, Nippon Kayaku Co., Ltd. HDDA: 1,6-hexanediol diacrylate, Nippon Kayaku Co., Ltd. TC-101: Tetrahydrofurfuryl acrylate, Nippon Kayaku Co., Ltd. DPHA: Dipentaerythritol hexaacrylate, Nippon Kayaku Co., Ltd.

(E) Other additives F-202: Fluorine block copolymer (Modiper F-202) Surface modifier made by NOF Corporation

(F) Alcohol (low boiling alcohol solvent (D))
IPA: isopropyl alcohol (boiling point 83 ° C)
MeOH: methyl alcohol (boiling point 65 ° C.)

  From the results shown in Table 1, (meth) acrylate compound having a hydroxyl group in the molecule (component (A)), conductive metal oxide having an average particle size of 0.1 μm or less (component (B)), and photopolymerization start In the hard coat agent prepared using a low boiling point alcohol solvent (component (D)) with the agent (component (C)), the total amount of solids contained in the hard coat agent is 30 wt. % To 89% by weight, (B) component 10% to 30% by weight, and (C) component 0.5% to 20% by weight of the hard coating agent (Example 1 to Example 6) was actually used. It can be seen that a possible hard coat layer is obtained.

  In addition, together with a (meth) acrylate compound having a hydroxyl group in the molecule (component (A)), TC-101 (tetrahydrofurfuryl acrylate), which is a monofunctional ethylenically unsaturated group-containing compound, is 2.5% by weight (/ pair). In the case of a hard coating agent formulated with a mixed solvent of IPA (isopropyl alcohol) and MeOH (methyl alcohol) (Example 4), the abrasion resistance (Δhaze) slightly decreases. Although (Δhaze 5.0), it can be seen that performance that can be actually used as a hard coat layer is obtained.

  Further, even when the surface modifier F-202 (fluorine-based block copolymer (Modiper F-202)) is not added (Example 5), the stability of the hard coat agent is secured, It can be seen that the coat layer can be practically used, although the ease of wiping off the fingerprint is reduced.

  Furthermore, by making the content rate with respect to the total amount of solid content contained in the hard coat agent of the conductive metal oxide (component (B)) having an average particle diameter of 0.1 μm or less (Example 6) It can be seen that a hard coat layer having a transmittance of 95% or more at a wavelength of 405 nm can be obtained.

  Considering from the results of Examples 1 to 6, among the polymerizable compounds composed of the component (A) and other monomers, the amount of the tri- or higher functional polymerizable compound is 30% by weight based on the entire solid content. -80% by weight, the amount of the bifunctional polymerizable compound used is 0% by weight to 50% by weight, and the amount of the monofunctional polymerizable compound used is the solid content. It turns out that it is preferable that it is 0 to 4.5 weight% with respect to the whole.

  Further, in view of the wear resistance, considering the results that Examples 1 to 3, 5 and 6 are better than Example 4, the amount of the tri- or higher functional polymerizable compound used is 30 wt% to 80 wt% based on the whole, and the amount of the bifunctional polymerizable compound used is 5 wt% to 50 wt% based on the entire solid content, and the monofunctional polymerizable compound It can be seen that the amount of is preferably 0 to 4.5% by weight based on the entire solid content.

(Comparative Examples 1 to 7)
Table 2 shows the composition of each component (parts by weight and parts by weight) of the ultraviolet curable hard coat agent used in each of (Comparative Examples 1 to 7).
The hard coat agent shown in Table 2 was prepared by blending each component by a conventional method.

In addition, the symbol of each composition shown in Table 2 is as follows.
(A) (A) component ((meth) acrylate compound (A) having a hydroxyl group in the molecule)
PET-30: pentaerythritol triacrylate, manufactured by Nippon Kayaku Co., Ltd. R-167: 1,6-hexanediol epoxy acrylate, manufactured by Nippon Kayaku Co., Ltd. R-115: bisphenol A type epoxy acrylate, Nippon Kayaku Made by Co., Ltd.

(B) Component (B) (conductive metal oxide (B) having an average particle size of 0.1 μm or less)
Zinc antimonate: an organosol of zinc antimonate having an average primary particle size of 0.1 μm or less by a dynamic scattering method

(C) (C) component (photoinitiator (C))
IRG-184: 1-hydroxycyclohexyl phenyl ketone, manufactured by Ciba Specialty Chemicals Co., Ltd. IRG-907: 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, Ciba Specialty Made by Chemical Corporation

(D) Other monomers DPHA: Dipentaerythritol hexaacrylate, Nippon Kayaku Co., Ltd. HDDA: 1,6-hexanediol diacrylate, Nippon Kayaku Co., Ltd. TC-101: Tetrahydrofurfuryl acrylate, Japan Kayaku Co., Ltd. TMPTA: Trimethylolpropane triacrylate, Nippon Kayaku Co., Ltd. R-684: Tricyclodecane dimethylol diacrylate, Nippon Kayaku Co., Ltd.

(E) Other additives F-202: Fluorine-based block copolymer (Modiper F-202) manufactured by NOF Corporation Surface modifier A-1100: Silane coupling agent, manufactured by Nippon Unicar Co., Ltd.

(F) Alcohol (low boiling alcohol solvent (D))
IPA: isopropyl alcohol (boiling point 83 ° C)
MeOH: methyl alcohol (boiling point 65 ° C.)

(G) Other solvents / PGM: Propylene glycol monomethyl ether (boiling point 120 ° C.)
MIBK: methyl isobutyl ketone (boiling point 115 ° C.)

  The hard coat agent in Comparative Example 1 does not use the (meth) acrylate compound (A) having a hydroxyl group in the molecule, and other monomers (TC-101: tetrahydrofurfuryl acrylate, TMPTA: trimethylolpropane triacrylate, R- 684: tricyclodecane dimethylol diacrylate).

  As shown in Table 2, the hard coat agent not containing the (meth) acrylate compound (A) having a hydroxyl group in the molecule is an evaluation result (abrasion resistance (Δhaze), fingerprint (Easy wiping, total light transmittance, surface resistivity) are obtained, but after standing in a constant temperature dryer at 40 ° C. for 1 month, the zinc antimonate sol shows aggregation and sedimentation (hard coat) Agent stability: x), it can be seen that the stability as a hard coat agent is insufficient. Also, the total light transmittance was a relatively low value (80%).

In the hard coat agent in Comparative Example 2, the content of the conductive metal oxide (B) (zinc antimonate) having an average particle size of 0.1 μm or less is less than 10% by weight based on the total solid content of the hard coat agent ( 6.7% by weight). As shown in Table 2, when the content of the component (B) is less than 10% by weight with respect to the total solid content of the hard coating agent, the surface resistivity increases (≧ 10 ¹⁴ Ω / □), and charging It can be seen that the prevention performance decreases.

  In the hard coat agent in Comparative Example 3, the content of the conductive metal oxide (B) having an average particle size of 0.1 μm or less exceeds 30 wt% with respect to the total solid content of the hard coat agent (30.9 wt. %). As shown in Table 2, when the content of the component (B) exceeds 30% by weight with respect to the total solid content of the hard coating agent, the total light transmittance is reduced (75%), and the light transmittance is reduced. It turns out that it falls.

  The hard coat agent in Comparative Example 4 is prepared using a high boiling point solvent (PGM: propylene glycol monomethyl ether (boiling point 120 ° C.)). As shown in Table 2, when a hard coat layer prepared using PGM is prepared, the PGM which is a high boiling point solvent is cured while remaining, so that the wear resistance (Δhaze) is lowered, and the substrate and It can be seen that the adhesion cannot be obtained.

  The hard coat agent in Comparative Example 5 was prepared using a solvent (MIBK: methyl isobutyl ketone (boiling point 115 ° C.)) different from the alcohol solvent. As shown in Table 2, it can be seen that when a hard coat layer is prepared using MIBK, the polycarbonate substrate is dissolved by MIBK and the substrate is whitened.

  The hard coat agent in Comparative Example 6 is prepared using a conductive metal oxide sol (zinc antimonate) having an average particle size larger than 0.1 μm (0.15 μm to 0.2 μm). As shown in Table 2, it can be seen that the total light transmittance is reduced (70%) when prepared using a zinc antimonate sol having an average particle size larger than 0.1 μm.

  The hard coat agent in Comparative Example 7 is prepared by adding a silane coupling agent (A-1100). As shown in Table 2, it can be seen that by adding the silane coupling agent (A-1100), the zinc antimonate sol aggregates, the stability of the hard coating agent is lowered, and the hard coat layer is whitened.

(Example 7)
Next, a hard coat layer was formed on a polycarbonate substrate on the light incident surface side of a write-once DVD (commercially available product: manufactured by Mitsubishi Chemical Media Corporation) using the ultraviolet curable hard coat agent evaluated in Example 1. . The conditions for forming the hard coat layer are as described in the test disk described above.
When a durability test (held at 80 ° C./80% RH for 250 hours) was performed on the write-once DVD with the hard coat layer formed in this way, there was no difference in the data of recording / reproduction characteristics before and after the durability test. I understood it. The results are shown in Table 3.

  From the results in Table 3, it was confirmed that the hard coat layer obtained using the hard coat agent of the present invention by the production method of the present invention was excellent in the durability test.

  In Table 3, PIsum8 and POF are a kind of recording / reproducing characteristics of the optical disc and indicate the number of errors. The larger these values are, the more the data stored on the optical disk is degraded.

  In Table 3, PIsum8 is “280 or less” in the DVD standard. On the other hand, since POF is the number of errors that cannot be repaired, there is a possibility that data cannot be read when POF occurs. Note that a commercially available drive (DW1620PRO manufactured by BENQ) was used for writing to the test disk (recordable DVD). The writing speed was 8 × speed, and the recording / reproduction characteristic data evaluation apparatus measured errors using DVD-CATS (SA300) manufactured by Audio Development.

Claims (14)

A (meth) acrylate compound (A) having a hydroxyl group in the molecule;
A conductive metal oxide (B) having a particle size measured by the BET method of 18 nm or less or an average particle size of 0.1 μm or less measured by a dynamic scattering method;
A photopolymerization initiator (C);
A low-boiling alcohol solvent (D), and a hard coating agent comprising:
(A) 30% by weight to 89% by weight, (B) 10% by weight to 30% by weight, and (C) 0.5% by weight to 20% by weight, based on the total amount of solids contained in the hard coat agent. A hard coat agent for an optical disc, characterized by comprising:   The hard coating agent for an optical disk according to claim 1, wherein the low boiling alcohol solvent (D) has a boiling point of 100 ° C or lower.   2. The hard coat agent for an optical disk according to claim 1, wherein the conductive metal oxide (B) is zinc antimonate. For the total amount of solids contained in the hard coat agent,
2. The hard coat agent for an optical disk according to claim 1, wherein the content of the monofunctional ethylenically unsaturated group-containing compound is 4.5% by weight or less.   2. The hard coat agent for an optical disk according to claim 1, wherein the conductive metal oxide (B) is contained in an amount of 10% by weight to 14% by weight with respect to the total amount of solids contained in the hard coat agent. A method of manufacturing an optical disk with a hard coat layer,
(Meth) acrylate compound (A) containing a hydroxyl group in the molecule, conductive metal oxide having a particle size measured by BET method of 18 nm or less or an average particle size measured by dynamic scattering method of 0.1 μm or less (B) A hard coating agent containing a photopolymerization initiator (C) and a low-boiling alcohol solvent (D) is applied to the laser light incident surface side surface of the optical disk by spin coating at a rotational speed of 1000 rpm to 7000 rpm at room temperature. Applying and curing with ultraviolet light,
A hard coat layer having a total light transmittance of 80% to 95% and a surface resistivity of 2 × 10 ¹² Ω / □ or less is provided on the laser light incident surface side surface of the optical disc. An optical disk manufacturing method.   The compounding ratio of the (meth) acrylate compound (A) containing a hydroxyl group in the molecule is 30% by weight to 95% by weight with respect to the total solid content of the hard coat agent. The manufacturing method of the hard coat layer provision optical disk of description.   The hard coat layer-provided optical disk according to claim 6 or 7, wherein a content of the conductive metal oxide (B) with respect to a total amount of solids in the hard coat agent is 10 wt% to 30 wt%. Manufacturing method.   The method for producing an optical disk with a hard coat layer according to any one of claims 6 to 8, wherein the conductive metal oxide (B) is zinc antimonate.   The method for producing an optical disk with a hard coat layer according to any one of claims 6 to 9, wherein the low-boiling alcohol solvent (D) has a boiling point of 100 ° C or lower.   The method of manufacturing an optical disk with a hard coat layer according to any one of claims 6 to 10, wherein the spin coating method is performed at a temperature of 15C to 35C.   The method of manufacturing an optical disk with a hard coat layer according to claim 6, wherein the hard coat layer has a thickness of 1 μm to 5 μm.   The content rate of the said conductive metal oxide (B) with respect to the total amount of the solid content in the said hard-coat agent is 10 weight%-14 weight%, The any one of Claims 6 thru | or 12 characterized by the above-mentioned. Manufacturing method of optical disc with hard coat layer.   An optical disc manufactured by the method for manufacturing an optical disc with a hard coat layer according to any one of claims 6 to 13.