JP4268087B2 - optical disk - Google Patents

Description

  The present invention relates to an optical disc, and more particularly to the provision of antistatic performance to various objects such as an optical disc, and more particularly to an optical disc having excellent antistatic performance corresponding to higher recording density and larger capacity.

  In recent years, optical discs that record and / or reproduce using laser light, such as CDs (compact discs) and DVDs (digital versatile discs), are widely used as recording media for recording large volumes of digital data. . Laser light applied to the optical disk is collected by an optical system and forms a beam spot having a predetermined diameter in a layer for recording information. Therefore, in order to increase the recording density of the optical disc, it is necessary to make the laser light focusing spot smaller.

  Recently, in order to narrow down the condensing spot, the numerical aperture (NA) of the condensing lens is increased to about 0.85 and the wavelength of the laser light used is shortened to about 405 nm, thereby dramatically increasing the recording capacity. Blu-ray discs that have been developed have been proposed and put into practical use. This Blu-ray disc has a structure including at least a recording layer and a light transmission layer on a substrate, and a laser beam is incident from the light transmission layer side to perform recording and / or reproduction on the recording layer. Is what you do.

  Also, the surface of various display elements such as an optical recording medium, a magneto-optical recording medium, an optical lens, an optical filter, an antireflection film, and a liquid crystal display, a CRT display, a plasma display, an EL display, etc. is usually scratch-resistant. In order to ensure wear resistance, a protective layer (hard coat layer) is provided. These various objects often have dirt such as dust or dust on their surfaces depending on the use of the user. In particular, optical recording media and optical lenses used for recording and reproduction of these various objects are subject to dirt. This is a serious problem because the recording and reproduction of the information signal is significantly hindered.

  In particular, in the Blu-ray disc in which the condensing spot diameter is narrowed as described above, the influence of foreign matters adhering to the disc surface on the light incident surface side is particularly large. That is, if even a small amount of dust or dirt adheres to the disk surface, it may interfere with the optical path of the irradiation laser light and cause an error during recording / reproduction. Therefore, in order to prevent dust and dust from adhering, it is important to provide antistatic performance at least on the light incident surface side of the disk.

  Various studies have been made so far for imparting antistatic performance to an optical disc. For example, Patent Document 1 contains at least one of polyethylene glycol, polypropylene glycol, and derivatives thereof (meta). An optical disc protective coating agent comprising an acrylate compound, an alkali metal salt, an alkaline earth metal salt, and a protonic acid, and an ethylenically unsaturated group-containing compound, and having an antistatic ability The resin composition which can be used as such is described.

  Patent Document 2 has various performances such as excellent transparency and storage stability by mixing a surfactant containing a perfluoroalkyl group and an alkali metal with (meth) acrylic acid ester. In addition, an antistatic ultraviolet curable coating material capable of forming a coating film without bleeding out for a long period of time and an optical disk provided with the cured coating film are described.

Furthermore, Patent Document 3 also describes that an antistatic agent can be blended as a functional compounding agent for a predetermined curable composition constituting the thin film cover layer (light transmission layer), Nonionic antistatic agents, cationic antistatic agents, and anionic antistatic agents are listed.
Japanese Patent Laid-Open No. 3-153769 (claims, etc.) JP-A-8-92497 (Claims, [0008], etc.) JP 2003-173575 A ([0027], [0031], etc.)

  As described above, various techniques have been proposed for imparting antistatic performance to optical disks. However, as in the techniques described in Patent Documents 1 and 2, when antistatic performance is imparted to the coating layer provided on the light transmission layer, even if good antistatic performance is obtained in the initial stage, after storage, The antistatic performance may be impaired. Accordingly, there has been a demand for means capable of exhibiting good antistatic performance not only in the initial stage but also after storage in various objects such as the optical disk.

  Therefore, an object of the present invention is to provide a high recording density optical disc and various objects similar thereto, which have good antistatic performance in the initial stage and can maintain good antistatic performance even after storage. There is to do.

  As a result of intensive studies, the present inventors have found that the above-described problems can be solved by adopting the following configuration, and have completed the present invention.

  That is, the optical disc of the present invention is an optical disc that comprises at least an information layer, a light transmission layer, and a hard coat layer on a substrate, and performs recording and / or reproduction by irradiating a laser beam from the hard coat layer side. The light-transmitting layer contains a resin containing either one or both of an ether bond and a urethane bond, and an alkali metal salt.

  In the optical disk of the present invention, it is preferable that a hard coat layer is provided on the light transmission layer. The alkali metal salt is preferably a lithium salt, and the content thereof is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin. Furthermore, as said resin, polyether group containing urethane acrylate is suitable. Furthermore, the hard coat layer preferably contains fine silica particles, and it is also preferred that the surface contains either one or both of a fluorine-containing block copolymer and a fluorine-containing polyether compound.

  The optical disk of the present invention is suitable as a so-called Blu-ray disk that is recorded and / or reproduced using a laser beam having a wavelength of 380 to 450 nm in a recording / reproducing apparatus having an objective lens numerical aperture NA of 0.85 or more. is there.

  Further, the object of the present invention comprises a resin layer and a hard coat layer on the surface in order, and the resin layer comprises a resin containing either one or both of an ether bond and a urethane bond, and an alkali metal salt. It is characterized by comprising.

  According to the present invention, a lithium metal salt is contained in the light transmission layer and a resin containing the specific structure is used as its main component, so that an excellent antistatic performance can be exhibited in the initial stage, and after storage. In addition, an optical disk capable of maintaining this antistatic performance can be realized. As described above, blending the antistatic agent in the light transmission layer is described in Patent Document 3, but is only listed as a kind of functional compounding agent in this document. There is no particular mention of the effects. Using a combination of the above specified resin and lithium metal salt, antistatic performance is imparted not only to the coating layer (hard cord layer) but also to the light transmission layer, so that a good antistatic effect not only in the initial stage but also after storage This is the first finding found in the present invention. The reason for this is considered as follows. That is, when an antistatic agent is added to the hard coat layer as in the prior art, the antistatic agent in the hard coat layer diffuses into the light-transmitting layer, which is a thicker layer, over time. There is a high possibility that the antistatic performance is lost due to bleed out (discharge) from the surface of the coat layer. Since such a problem does not occur in the present invention, it is possible to maintain good antistatic performance even after storage. In addition, according to the present invention, good antistatic performance can be obtained in various objects such as an optical lens while ensuring scratch resistance and wear resistance, as in the case of the optical disk.

Hereinafter, specific embodiments of the present invention will be described in detail.
FIG. 1 shows an example of the configuration of the optical disk of the present invention. An optical disk 10 shown in the figure has a configuration in which a recording layer 2 and a light transmission layer 3 are sequentially provided on a substrate 1 and further a hard coat layer 4 is formed, and laser light is irradiated from the light transmission layer 3 side. Thus, recording and / or reproduction is performed. Here, the light transmission layer 3 is a layer through which laser light is transmitted when recording and / or reproduction laser light is applied to the recording layer 2 or reflected from the recording layer 2.

  In the present invention, it is important that the light transmission layer 3 contains a resin containing either one or both of an ether bond and a urethane bond and an alkali metal salt. By configuring the light transmission layer 3 in such a combination, an optical disc that can exhibit good antistatic performance even after storage can be obtained.

  As the resin used for the light transmission layer 3, it is necessary to use a resin that easily causes alkali metal ions to move due to the relationship with the alkali metal salt, thereby easily causing ion conduction. For example, when the light transmissive layer 3 is composed mainly of a resin containing an ether bond, the ether oxygen constituting the resin matrix forms a coordination field such as crown ether and takes in alkali metal ions. Since the alkali metal ions taken in are considered to dissolve and are in a state of being easily moved by the molecular vibration of ether oxygen, when an electric field is applied from the outside in this state, they move toward the corresponding pole. Thereby, ionic conduction is exhibited. Even when a resin containing a urethane bond is used, it is considered that the same effect as described above can be obtained by the action of a nitrogen atom and an oxygen atom in the urethane bond. In the present invention, both the ether bond and the urethane bond are obtained. By using a resin containing, further excellent conductivity is realized. Thereby, an antistatic performance is given to the optical disc.

  Examples of the resin containing an ether bond include polyethylene glycol, polypropylene glycol, polybutylene glycol, a copolymer of polyethylene glycol and polypropylene glycol, methoxy (poly) ethylene glycol (meth) acrylate, and ethoxy (poly) ethylene glycol. Monofunctional acrylates such as (meth) acrylate, phenoxy (poly) ethylene glycol (meth) acrylate, bifunctional acrylates such as polyethylene glycol di (meth) acrylate, EO-modified trimethylolpropane triacrylate (trade name: Light acrylate TMP-3EO -A, manufactured by Kyoeisha Chemical Co., Ltd.). Two or more of these may be used in combination.

  As resin containing a urethane bond, the polyurethane produced | generated by reaction of a polyol and diisocyanate is mentioned, for example. Polyols include polyethylene glycol, polypropylene glycol, polybutylene glycol, polycaprolactone diol, polycaprolactone triol, polycarbonate diol, acrylic polyol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, silicone Various known materials such as polyol can be used. Diisocyanates include tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI) for aromatics, and alicyclic such as hexamethylene diisocyanate (HDI) for aliphatics. Examples include isophorone diisocyanate and methylene bis (4-cyclohexyl isocyanate) (hydrogenated MDI). The reaction between these polyols and diisocyanates may be carried out by a known method and is not particularly limited.

  In addition, urethane acrylate which is a reaction product of polyol, diisocyanate and hydroxyl group-containing ethylenically unsaturated compound can also be suitably used in the present invention. Examples of the hydroxyl group-containing ethylenically unsaturated compound include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, and pentaerythritol tri (meth) acrylate. And so on. These reactions may be carried out by known methods and are not particularly limited.

  The resin containing both an ether bond and a urethane bond is produced by a polyether polyurethane produced by a polyurethane comprising a polyether polyol and a diisocyanate, or produced by a polyether polyol, a diisocyanate and a hydroxyl group-containing ethylenically unsaturated compound. Examples thereof include polyether group-containing urethane acrylate. The polyether polyol is preferably polyethylene glycol, polypropylene glycol or polybutylene glycol, the diisocyanate is preferably isophorone diisocyanate or methylene bis (4-cyclohexyl isocyanate), and the hydroxyl group-containing ethylenically unsaturated compound is Preferably, 2-hydroxyethyl (meth) acrylate or pentaerythritol tri (meth) acrylate can be used. In addition to the above, known resins can be mixed and used.

  The content of the resin containing an ether bond and / or a urethane bond in the light transmission layer 3 is preferably 5 to 95% by weight. By setting the resin content to 5% by weight or more, sufficient ion conductivity can be obtained. On the other hand, when it exceeds 95% by weight, an alkali metal salt, a photoinitiator or the like cannot be contained sufficiently.

Examples of the alkali metal salt that can be used for the light-transmitting layer 3 include lithium salts, potassium salts, sodium salts, and the like, and lithium salts are particularly preferable from the viewpoint of excellent compatibility with resins and solvents. Specific examples of the lithium salt include lithium trifluoromethanesulfonate (CF ₃ SO ₃ Li), lithium bistrifluoromethanesulfonylimide (Li (CF ₃ SO ₂ ) ₂ N), lithium bispentafluoroethanesulfonylimide (Li (C ₂ F ₅ SO ₂ ) ₂ N), lithium perfluorooctane sulfonate (C ₈ F ₁₇ SO ₃ Li), lithium borofluoride (LiBF ₄ ), and the like. Other Li ⁺ counter ions include ClO ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₅ ⁻ , C ₄ F ₉ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , and B (C ₆ H ₅ ) _4- ^{and the} like can be mentioned, and two or more of the above alkali metal salts can be used in combination as appropriate. Particularly preferred is CF ₃ SO ₃ Li, Li (CF ₃ SO ₂ ) ₂ N, or C ₈ F ₁₇ SO ₃ Li. Among them, Li is easy to ionize, and the anion side has a small molecular weight and conducts. Li (CF ₃ SO ₂ ) ₂ N is more preferable because of its high rate. Two or more of these may be used.

  The content of the alkali metal salt is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 1 to 5 parts by weight with respect to 100 parts by weight of the resin. When the content of the alkali metal salt is 0.1 parts by weight or more, sufficient antistatic performance can be obtained, while there is almost no difference in the antistatic function even when the content exceeds 10 parts by weight. In addition, it may affect physical properties such as light transmission. In addition, adverse effects such as yellowing and corrosion may occur.

  The light transmission layer 3 is formed by applying a coating liquid made of the above-described constituent material on the first derivative layer 7 and then irradiating it with ultraviolet rays or an electron beam according to the resin, or curing by heat. As a coating method, for example, a spin coating method can be used. By using a laser beam having an objective lens NA of 0.8 or more and a wavelength of 380 to 450 nm, the spot diameter of the laser beam can be remarkably reduced to increase the surface recording density. On the other hand, the optical axis and the optical axis of the laser beam In contrast to this, the angle error allowed for the inclination becomes narrow, but by arranging a thin light transmission layer between the recording layer and the laser beam lens, a large angle error can be secured. For this reason, the thickness of the light transmission layer 3 is about 30 to 300 μm, preferably about 50 to 150 μm.

  Moreover, in this invention, the light transmissive resin sheet containing the said resin and alkali metal salt previously is produced, and the light transmissive layer 3 can also be formed using this sheet | seat. In this case, first, an ultraviolet curable material similar to that for the light transmission layer is applied on the first dielectric layer 7 to form an uncured resin material layer. Next, a light-transmitting resin sheet as the light-transmitting layer 3 is placed thereon, and then the resin material layer is cured by irradiating with ultraviolet rays, thereby adhering the light-transmitting resin sheet. 3.

  The present invention can be applied regardless of the type of information layer as long as the above conditions are satisfied with respect to the light transmission layer. Here, the information layer is a layer including at least a recording layer, and may include a dielectric layer, a reflective layer, and the like. The recording layer can be applied to a rewritable recording medium such as phase change, a write-once recording medium using a dye or an inorganic film, or a magneto-optical recording medium. As will be described below with reference to FIG. 2, a dielectric layer and a reflective layer are provided on at least one side of the recording layer as needed for the purpose of protecting the recording layer and for optical effects. Further, the present invention is not limited to the recordable type as shown in the figure, but can also be applied to a reproduction-only type. In this case, information is recorded by forming irregularities on the surface of the substrate or the spacer layer. In this case, this uneven portion is used as an information layer. If necessary, a reflective layer (metal layer or derivative multilayer film) covering the pit row is formed.

Hereinafter, the optical disk of the present invention will be described with respect to the phase change type.
FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the optical disc of the present invention. The optical disk 20 shown in FIG. 2 includes a reflective layer 15, a second dielectric layer 16, a phase change recording material layer 12, and a surface on the side of the substrate 1 on which fine irregularities such as information pits and pregroups are formed. The first dielectric layer 17 and the light transmission layer 3 are sequentially provided, and the hard coat layer 4 is further formed on the light transmission layer 3. In the illustrated example, the reflective layer 15, the second dielectric layer 16, the phase change recording material layer 12 and the first dielectric layer 17 constitute an information layer, and the information layer and the light transmission layer 3 are recorded or reproduced. Therefore, a necessary film body is formed. In the optical disc 20, recording / reproducing laser light is incident through the hard coat layer 4 and the light transmission layer 3, that is, from the film body side.

  The substrate 1 can usually have a thickness of about 0.3 to 1.6 mm, preferably about 0.4 to 1.3 mm. On the surface on which the recording layer 2 is formed, information pits, pregroups, etc. Fine irregularities are formed. Since the optical disk of the present invention is used so that the laser beam is incident from the film body side as described above, the substrate 1 does not have to be optically transparent. Examples thereof include polycarbonate resins, acrylic resins such as polymethyl methacrylate (PMMA), and various plastic materials such as polyolefin resins. Moreover, you may use glass, ceramics, a metal, etc. The uneven pattern on the surface can be formed by injection molding when a plastic material is used, and can be formed by a photopolymer method (2P method) other than the plastic material.

  The reflective layer 15 can be formed on the substrate 1 by a sputtering method, and is not essential in the present invention. As a material for the reflective layer 15, a metal element, a metalloid element, a semiconductor element, or a compound thereof can be used alone or in combination. Specifically, for example, a known reflective layer material such as Au, Cu, Al, or Pd may be selected.

  The phase change recording material layer 12 is formed of a material that changes reversibly between a crystalline state and an amorphous state by laser light irradiation, and has different optical characteristics between the two states. Specific examples of such materials include Ge—Sb—Te, In—Sb—Te, Sn—Se—Te, Gs—Te—Sn, In—Se—Tl, In—Sb—Te, and the like. Can do.

  In the illustrated example, the second dielectric layer 16 and the first dielectric layer 17 are provided on both upper and lower sides of the phase change recording material layer 12, but these are not essential in the present invention. . These layers have a function of protecting the phase change recording material layer 12 mechanically or chemically and a function of an interference layer for adjusting optical characteristics. Both the second dielectric layer 16 and the first dielectric layer 17 may be formed of a single layer or may be formed of a plurality of layers. In addition, the dielectric layer may serve as a recording layer.

The second dielectric layer 16 and the first dielectric layer 17 are made of Si, Zn, Al, Ta, Ti, Co, Zr, Pb, Ag, Zn, Sn, Ca, Ce, V, Cu, Fe, and Mg, respectively. It is preferably formed from an oxide, nitride, sulfide, fluoride, or a composite thereof containing at least one of the selected metals. In particular, SiO ₂ and Al ₂ O ₃ are preferable because they are chemically stable. Further, the extinction coefficient k of each of these layers is preferably 0.1 or less.

  The second dielectric layer 16, the phase change recording material layer 12, and the first dielectric layer 17 can be formed by sputtering.

  The hard coat layer 4 is provided on the light transmissive layer 3. Specifically, the hard coat agent composition is applied on the light transmissive layer 3 to form an uncured hard coat layer, and then ultraviolet rays are formed. It can be formed by irradiating an active energy ray such as an electron beam or visible light and curing.

  The hard coat agent composition used for forming the hard coat layer 4 is not particularly limited, and can be configured by appropriately using materials that are usually applied to the hard coat layer. The fluorine-containing hard coat agent composition described in 1) is used. By using the following hard coat agent composition, the fluorine component exhibits antifouling properties (oil repellency, water repellency) and lubricity, and also forms a hard coat layer with excellent scratch resistance and wear resistance. And the incident surface of the recording / reproducing laser beam can be optimized. When the following fluorine compound is used, excellent antifouling properties (oil repellency and water repellency) and lubricity can be obtained, but the surface is easily charged with static electricity, and as a result, dust and dust are easily sucked. In the present invention, since the above-described materials are used for the light transmission layer, even if the fluorine-containing hard coat agent composition described below is used, the antistatic effect is excellent. Although the number of steps is increased, the same effect can be obtained by applying the following fluorine compound on a normal hard coat layer and reacting with an active energy ray to fix it.

  The hard coat agent composition suitable for the present invention comprises a fluorine-containing block copolymer (A1) and / or a fluorine-containing polyether compound (A2) having an active energy ray-reactive group and an active energy ray-curable compound (B ).

  Of these, the active energy ray-curable compound (B) is other than the fluorine-containing block copolymer (A1) and the fluorine-containing polyether compound (A2), and is the main component of the curable component in the hard coat agent composition. The matrix of the hard coat layer obtained after curing is formed. The structure of the active energy ray-curable compound (B) is not particularly limited as long as it is a compound having at least one active energy ray polymerizable group selected from a (meth) acryloyl group, a vinyl group, and a mercapto group. . In addition, the active energy ray-curable compound (B) does not contain fluorine in order to obtain sufficient hardness as a hard coat, and contains two or more, preferably three or more polymerizable groups in one molecule. It preferably contains a functional monomer or oligomer.

  Among such active energy ray-curable compounds (B), examples of the compound having a (meth) acryloyl group include urethane acrylate, epoxy acrylate, ester acrylate, and the like. Specifically, 1,6-hexanediol (Meth) acrylate, triethylene glycol di (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate Dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate, 3- (meth) acryloyloxyglycerin mono (meth) acrylate, and the like. It is not necessarily to be limited to these.

  Only 1 type may be used for this active energy ray hardening compound (B), and 2 or more types may be used together.

  The fluorine-containing block copolymer (A1) is used for imparting antifouling properties and lubricity to the hard coat layer surface, and includes a fluorine-containing segment and a hydroxyl group-containing segment.

The fluorine-containing segment has the following general formula (1),
CH ₂ = CR ¹ COOR ² Rf (1)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents —C _p H _2p —, —C (C _p H _{2p + 1} ) H—, —CH ₂ C (C _p H _{2p + 1} ) H— or —CH ₂ CH ₂ O—, wherein Rf is —C _n F _{2n + 1} , — (CF ₂ ) _n H, — (CF ₂ ) _p OC _n H _2n C _i F _{2i + 1} , — (CF ₂ ) _p OC _m H _2m C _i F _2i H, —N (C _p H _{2p + 1} ) COC _n F _{2n + 1} , or —N (C _p H _{2p + 1} ) SO ₂ C _n F _{2n + 1} , p is 1 to 10, n is 1 to 16, m is 0 to 10, i is an integer of 0 to 16), or the above general It is formed from a fluorine-containing monomer represented by the formula (1) and a radical polymerizable monomer not containing a hydroxyl group. The fluorine-containing segment imparts antifouling properties and / or lubricity to the hard coat layer surface.

Specific examples of the fluorine-containing monomer represented by the general formula (1) include CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ OCOCH═CH ₂ , CF ₃ CH ₂ OCOCH═CH ₂ , CF _{3 (CF 2) 4 CH 2} CH 2 OCOC (CH 3) = can be exemplified CH ₂ and the like. These can be used by appropriately selecting one kind or two or more kinds.

  Specific examples of the radical polymerizable monomer containing no hydroxyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, Stearyl (meth) acrylate, lauryl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, tetrahydro And furfuryl (meth) acrylate. One or more of these monomers can be appropriately selected and used.

  On the other hand, the hydroxyl group-containing segment has an effect on the compatibility of the active energy ray-curable compound (B) with the polymer. The hydroxyl group-containing segment may be formed from a hydroxyl group-containing radical polymerizable monomer. Examples of such a hydroxyl group-containing radical polymerizable monomer include 2-hydroxyethyl (meth) acrylate, ethylene glycol monoester. (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, 2-hydroxy-3-butoxypropyl (meth) acrylate, 2-hydroxy-3- (2- And ethylhexyloxy) propyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, and the like. Among these monomers, one or more can be appropriately selected and used.

  The synthesis of the fluorine-containing block copolymer (A1) is carried out using a polymer peroxide or a polyazo compound, and the usual bulk polymerization method, suspension polymerization method, solution polymerization method and emulsion polymerization method are performed in two steps. Any known various methods may be used.

  In the fluorine-containing block copolymer (A1), the weight ratio (f / h) between the fluorine-containing segment (f) and the hydroxyl group-containing segment (h) is preferably 10/90 to 90/10, / 80 to 80/20 is more preferable. When the proportion of the fluorine-containing segment (f) exceeds 90% by weight, the compatibility of the hard coating composition is deteriorated, and the entanglement effect with the active energy ray-curable compound (B) is diminished and the durability is lowered. To do. On the other hand, when the ratio of the fluorine-containing segment (f) is less than 10% by weight, the water / oil repellency becomes insufficient, and the function of fluorine cannot be sufficiently exhibited.

  Furthermore, in the fluorine-containing block copolymer (A1), an active energy ray-reactive group is introduced into the hydroxyl group-containing segment through a urethane bond in order to improve immobilization in the hard coat layer. It is preferable. When the active energy ray reactive group is introduced, the crosslinking reaction between the fluorine-containing block copolymers (A1) and the fluorine-containing polyether compound (by the active energy ray irradiation when the hard coat layer is cured) A crosslinking reaction with A2) and a crosslinking reaction with the active energy ray-curable compound (B) occur, and the immobilization in the hard coat layer is further improved. As a result, a hard coat layer having very excellent antifouling properties and lubricity is formed under various storage conditions and use conditions. Examples of the active energy ray reactive group include a (meth) acryloyl group and a vinyl group.

  The fluorine-containing block copolymer (A1) is obtained by reacting a hydroxyl group-containing segment with a monomer having one ethylenically unsaturated double bond and one isocyanate group in the molecule, thereby causing the hydroxyl group and the isocyanate group to react. It is preferable that an ethylenically unsaturated double bond is introduced through a derived urethane bond. Thus, the fluorine-containing block copolymer (A1) into which the active energy ray double bond is introduced can suppress the thickening of the liquid of the hard coat agent composition. Examples of such monomers include isocyanate ethyl (meth) acrylate and methacryloyl isocyanate.

  The fluorine-containing block polymer (A1) preferably has a molecular weight of about 5,000 to 100,000 from the viewpoint of immobilization effect in the hard coat layer. When the molecular weight is less than 5,000, the immobilization effect is difficult to obtain when the active energy ray-reactive double bond is not present. On the other hand, when the molecular weight exceeds 100,000, the solubility in the hard coat layer is deteriorated, and it is difficult to migrate to the surface after coating.

  Specific examples of the fluorine-containing block copolymer (A1) include Modiper F220, F600, F2020, F3035 (manufactured by Nippon Oil & Fats Co., Ltd.), and (meth) acryloyl group and vinyl group are introduced into these. Those having a (meth) acryloyl group introduced via a urethane bond are also preferred. Only 1 type may be used for this fluorine-containing block copolymer (A1), and it may use 2 or more types together.

  The fluorine-containing polyether compound (A2) is a compound having a perfluoropolyether moiety and at least one active energy ray reactive group, and is used for imparting antifouling properties and lubricity to the hard coat layer surface. . Examples of the active energy ray reactive group include a (meth) acryloyl group and a vinyl group. The perfluoropolyether part imparts antifouling properties and lubricity to the hard coat layer surface. The perfluoropolyether moiety is more likely to collect on the surface of the hard coat layer than the fluorinated alkyl moiety of the fluorinated alkyl (meth) acrylate, and imparts better antifouling properties and / or lubricity. On the other hand, by having an active energy ray-reactive group, a crosslinking reaction between fluorine-containing polyether compounds (A2) or a fluorine-containing block copolymer (A) by irradiation with active energy rays when the hard coat layer is cured. The cross-linking reaction with A1) and the cross-linking reaction with the active energy ray-curable compound (B) occur, and the immobilization in the hard coat layer is improved. As a result, a hard coat layer having very excellent antifouling properties and lubricity is formed under various storage conditions and use conditions.

  In addition, the effect of imparting antifouling property / lubricity to the hard coat layer surface of the fluorine-containing polyether compound (A2) is higher than that of the above-described fluorine-containing block copolymer (A1).

  Since the fluorine-containing polyether compound (A2) having two or more active energy ray reactive groups in the molecule improves immobilization in the hard coat layer, and also improves antifouling properties and lubricity. preferable. The fluorine-containing polyether compound (A2) preferably has active energy ray-reactive groups at both ends of the molecule because the immobilization in the hard coat layer is further improved. Those having two active energy ray reactive groups are more preferable.

  Further, the fluorine-containing polyether compound (A2) preferably has one or more active energy ray reactive groups per 1000 formula weights and has two or more active energy ray reactive groups per 1000 formula weights. More preferred are those having 4 or more active energy ray reactive groups per 1000 formula weights. The molecular weight is preferably 500 or more and 5000 or less, and more preferably 800 or more and 3000 or less. By using these preferable fluorine-containing polyether compounds (A2), immobilization in the hard coat layer can be further improved, and a hard coat layer having excellent solvent resistance can be obtained.

  The fluorine-containing polyether compound (A2) is obtained by introducing a (meth) acryloyl group into a hydroxyl group using a fluorine-containing polyether compound having a hydroxyl group at the terminal as a raw material. Examples of the fluorine-containing polyether compound as a raw material include the following compounds, but are not limited thereto.

_{HOCH 2 -CF 2 O- [CF 2} CF 2 O] s - [CF 2 O] m -CF 2 CH 2 OH
(Z DOL)
_{F- [CF 2 CF 2 CF 2} O] s -CF 2 CF 2 CH 2 OH
(Demnum-SA)
_{F- [CF (CF 3) CF} 2 O] s -CF (CF 3) CH 2 OH
(Krytox-OH)
_{HO (CH 2 CH 2 O)} n -CH 2 -CF 2 O- [CF 2 CF 2 O] s - [CF 2 O] m -CF 2 CH 2 (OCH 2 CH 2) n OH
(Zdol-TX)
_{HOCH 2 CH (OH) CH 2} OCH 2 -CF 2 O- [CF 2 CF 2 O] s - [CF 2 O] m -CF 2 CH 2 OCH 2 CH (OH) CH 2 OH
(Z-Tetraol)

  Specific examples of the fluorine-containing polyether compound (A2) include a terminal hydroxyl group of Fomblin Z DOL diacrylate (Fomlin Z DOL (manufactured by Augmont)) having one or more active energy ray reactive groups per 1000 molecular weight. Acrylate modified) and fluorite ART4 (Kyoeisha Chemical Co., Ltd.), and those having two or more active energy ray reactive groups per 1000 molecular weight, such as fluorite ART3 (Kyoeisha Chemical Co., Ltd.), 4 per 1000 molecular weight. As what has the above active energy ray reactive group, what carried out the acrylate modification | denaturation etc. of the four terminal hydroxyl groups of Fomlin Z-Tetraol (made by an Audimond company) can be mentioned.

  Only 1 type may be used for this fluorine-containing polyether compound (A2), and it may use 2 or more types together.

  The hard coat agent composition suitable for the present invention comprises 0.05 to 5 parts by weight of a fluorine-containing block copolymer (A1) and 100 parts by weight of the nonvolatile content of the composition, and a fluorine-containing polyether compound. (A2) It is preferable to contain 0.01 to 3 parts by weight. Here, the nonvolatile content is a component remaining in the hard coat layer after curing, in addition to the fluorine-containing block copolymer (A1), the fluorine-containing polyether compound (A2) and the curable compound (B), Optional components such as a monofunctional monomer, inorganic fine particles (C) described later, a photopolymerization initiator, and various additives are included.

  Further, the fluorine-containing polyether compound (A2) has a high effect of imparting water repellency / lubricity to the hard coat layer surface, but when only this is used as a water repellency / lubricity imparting component, In some cases, white turbidity that appears to be a pseudo-collection of the fluorine-containing polyether compound (A2) may occur. By using the fluorine-containing block copolymer (A1) together with the fluorine-containing polyether compound (A2) in an amount within the above range, the occurrence of white turbidity can be suppressed, and the coating property of the hard coat agent composition liquid can be reduced. Improved. As a result, a hard coat layer having good surface properties can be obtained. The reason why generation of white turbidity can be suppressed by the addition of the fluorine-containing block copolymer (A1) is not clear, but is presumed as follows. That is, the fluorine-containing block copolymer (A1) has a very high affinity with the hard coat agent composition liquid and is also a fluorine-containing compound with respect to the affinity with the fluorine-containing polyether compound (A2). That's expensive. Therefore, it is estimated that the fluorine-containing block copolymer (A1) plays a role of assisting solubility in the fluorine-containing polyether compound (A2).

  The addition amount of the more preferable fluorine-containing block copolymer (A1) is 0.05 part by weight or more and 3 parts by weight or less, but even when added in an amount of more than 0.5 part by weight, the white turbidity suppressing effect is saturated, In addition, since there is a tendency that foaming occurs in the hard coating agent composition liquid, the most preferable addition amount of the fluorine-containing block copolymer (A1) is 0.05 part by weight or more and 0.5 part by weight or less. In addition, since this foaming can be improved by a detreatment process etc., you may add more than 0.5 weight part of fluorine-containing block copolymers (A1) as needed.

  A more preferable addition amount of the fluorine-containing polyether compound (A2) is 0.05 part by weight or more and 1 part by weight or less. The imparting effect is saturated, and the hardness of the hard coat surface tends to decrease with it. On the other hand, if it is less than 0.2 part by weight, water repellency may not be obtained sufficiently, so the most preferable fluorine-containing The addition amount of the polyether compound (A2) is 0.2 parts by weight or more and 0.5 parts by weight or less. Further, the fluorine-containing block copolymer (A1) and / or the fluorine-containing polyether compound (A2) is applied onto the surface of the hard coat layer, whereby the fluorine-containing block copolymer (A1) is formed on the surface of the hard coat layer. And / or a fluorine-containing polyether compound (A2) can be contained.

  As described above, by using the fluorine-containing block copolymer (A1) and the fluorine-containing polyether compound (A2) in combination in order to impart water repellency and lubricity to the hard coat layer surface, the coatability is good. In addition, a hard coat agent composition having excellent water repellency, lubricity and durability on the surface of the hard coat layer after curing can be obtained.

  Moreover, it is preferable that this hard-coat agent composition contains an inorganic fine particle (C). The average particle diameter of the inorganic fine particles (C) is 100 nm or less, preferably 20 nm or less in order to ensure the transparency of the hard coat layer, and is preferably 5 nm or more due to restrictions on the production of the colloidal solution. .

  The inorganic fine particles (C) are, for example, fine particles of metal (or metalloid) oxide or fine particles of metal (or metalloid) sulfide. Examples of the metal or semimetal of the inorganic fine particles include Si, Ti, Al, Zn, Zr, In, Sn, and Sb. In addition to oxides and sulfides, Se, Te, nitrides, and carbides can also be used. Examples of the inorganic fine particles include fine particles such as silica, alumina, zirconia, and titania. Among them, silica fine particles are preferable. By adding such inorganic fine particles to the hard coat agent composition, the wear resistance of the hard coat layer can be further improved.

  As the silica fine particles, those finely modified with a hydrolyzable silane compound having an active energy ray reactive group are preferably used. Such reactive silica fine particles undergo a crosslinking reaction by irradiation with active energy rays when the hard coat layer is cured, and are fixed in the polymer matrix. Examples of such reactive silica fine particles include reactive silica particles described in JP-A-9-100111, which can be preferably used in the present invention.

  When the inorganic fine particles (C) are used, the content thereof is preferably 5 parts by weight or more and 500 parts by weight or less, and 20 parts by weight or more and 200 parts by weight or less with respect to 100 parts by weight of the curable compound (B). It is more preferable to be within the range. If the inorganic fine particles (C) are contained in an amount of more than 500 parts by weight, the film strength of the hard coat layer tends to be weak, whereas if it is less than 5 parts by weight, the wear resistance of the hard coat layer due to the addition of the inorganic fine particles (C). The improvement effect is weak.

  If necessary, in the light transmission layer or hard coat agent composition, a photopolymerization initiator, a non-polymerizable diluent solvent, an organic filler, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, an antifoaming agent. It may also contain an agent, leveling agent, silicone or the like. The hard coat agent composition can be produced by mixing each of the above components by a conventional method and adjusting the viscosity appropriately for coating.

  The application method of the hard coat layer 4 is not limited, and various application methods such as a spin coating method, a dip coating method, and a gravure coating method can be appropriately used. Moreover, when using a light-transmitting resin sheet as the light-transmitting layer 3, the hard coat layer 4 is formed in the same manner as previously described on the long light-transmitting resin sheet, It is also possible to use a method in which after the original fabric is punched into a disk shape, it is placed on an uncured resin material layer and the resin material layer is cured as described above.

  When the hard coat agent composition contains a non-reactive diluted organic solvent, the hard coat agent composition is applied to form an uncured hard coat layer, and then the non-reactive organic solvent is removed by heating and drying. Then, the hardened layer 4 is formed by curing the uncured layer by irradiation with active energy rays. A hard coat in which the fluorine-containing block copolymer (A1) and the fluorine-containing polyether compound (A2) are uncured by applying the hard coat agent composition using a diluted organic solvent and then removing the organic solvent by heating and drying. It becomes easy to gather more in the vicinity of the surface of the layer 4, and more of these components are present in the vicinity of the surface of the hard coat layer 4 after curing, so that a greater lubricity improving effect is easily obtained. In this case, the heat drying temperature is preferably 40 ° C. or more and 100 ° C. or less, for example. The heat drying time can be, for example, 30 seconds to 8 minutes, preferably 1 minute to 5 minutes, more preferably 3 minutes to 5 minutes. The non-reactive diluted organic solvent is not particularly limited, and propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol and the like are used. As the active energy ray, an appropriate one selected from active energy rays such as ultraviolet rays, electron beams and visible light may be selected and used, but preferably ultraviolet rays or electron beams are used. The film thickness of the hard coat layer 4 after curing is about 0.5 to 5 μm. From the viewpoint of scratch resistance and abrasion resistance of the hard coat layer, the hard coat layer is preferably pencil hardness of HB or higher, and preferably higher than the resin layer (light transmission layer).

  Although not shown, an optical disc having two or more recording layers in which a recording layer is further provided on the recording layer 2 via a spacer layer is also included in the present invention. In this case, the optical disc has the light transmission layer 3 on the recording layer farthest from the substrate 1.

  Since the optical disk of the present invention can exhibit excellent antistatic performance on the light incident side surface both in the initial stage and after storage, it can satisfactorily prevent dust and dirt from adhering to the disk surface. . Therefore, recording and / or reproduction is performed using a laser beam having a wavelength of 380 to 450 nm in an optical disk with a narrowed focusing spot diameter, particularly a recording / reproducing apparatus having an objective lens numerical aperture NA of 0.85 or more. Even when it is applied to a so-called Blu-ray disc, it is suitable without causing a recording / reproducing error due to dust or dust.

  The object of the present invention comprises, on the surface, a resin layer substantially corresponding to the light transmission layer in the optical disc and a hard coat layer similar to that in the optical disc, and the resin layer Any resin containing an ether bond and / or urethane bond as described above and an alkali metal salt may be used. Specifically, in addition to an optical recording medium and a magneto-optical recording medium, an optical lens, an optical filter, This is a broad concept including an antireflection film and optical members such as various display elements such as a liquid crystal display, a CRT display, a plasma display, and an EL display. According to the present invention, it is possible to obtain the same excellent antistatic performance as that of the optical disc as described above even in such various objects.

Hereinafter, the present invention will be described more specifically with reference to examples.
Examples 1 to 6 and Comparative Examples 1 and 2
The optical disk sample having the layer structure shown in FIG. 2 was produced as follows.
A disk-shaped substrate 1 (made of polycarbonate, diameter 120 mm, thickness 1.1 mm) on which a groove for recording information is formed has a thickness of 100 nm made of Al ₉₈ Pd ₁ Cu ₁ (atomic ratio). The reflective layer 15 was formed by a sputtering method. The depth of the groove was expressed as an optical path length at a wavelength λ = 405 nm and was λ / 6. The recording track pitch in the group recording method was 0.32 μm.

Next, a second dielectric layer 16 having a thickness of 20 nm was formed on the surface of the reflective layer 15 by sputtering using an Al ₂ O ₃ target. Further, a recording layer 12 having a thickness of 12 nm was formed on the surface of the second dielectric layer 16 by sputtering using an alloy target made of a phase change material. The composition (atomic ratio) of the recording layer 12 was Sb ₇₄ Te ₁₈ (Ge ₇ In ₁ ). Further thereon, a ZnS (80 mol%)-SiO ₂ (20 mol%) target was used to sequentially laminate a thickness of 100 nm by sputtering and a thickness of 40 nm using an SiO ₂ target. The first dielectric layer 17 having a total of 140 nm was formed.

Next, Li (CF ₃ SO ₃ ) ₂ N as an alkali metal salt is added and mixed in the parts shown in Table 1 below in a radical polymerizable ultraviolet curable material having the following composition A or B. The obtained light transmissive layer coating solution was applied to the surface of the first dielectric layer 17 by spin coating, irradiated with ultraviolet rays, and the light transmissive layer 3 was formed so that the thickness after curing was 98 μm. In addition, the following composition B contains resin containing an ether bond and a urethane bond.

Composition A
75 parts by weight of urethane acrylate (Polycarbonate diol (molecular weight 1000, trade name: NIPPOLAN 981, manufactured by Nippon Polyurethane Industry Co., Ltd.) polymerized at both ends with hydrogenated MDI and 2HEA)
Tetrahydrofurfuryl acrylate 25 parts by weight Irgacure 184 3 parts by weight (polymerization initiator, manufactured by Ciba Specialty Chemicals)

Composition B
Urethane acrylate 75 parts by weight (Polytetramethylene glycol (molecular weight 600, manufactured by Wako Pure Chemical Industries, Ltd.) polymerized at both ends with hydrogenated MDI and 2HEA).
Tetrahydrofurfuryl acrylate 25 parts by weight Irgacure 184 3 parts by weight (polymerization initiator, manufactured by Ciba Specialty Chemicals)

Next, an ultraviolet curable hard coat agent having the following composition C was applied onto the light transmitting layer 3 by a spin coating method to form a film, and the diluted solvent inside the film was removed by heating at 60 ° C. for 3 minutes in the air. Then, ultraviolet rays were irradiated to form a hard coat layer 4 having a thickness of 2 μm after curing. For Comparative Example 2 alone, Li (CF ₃ SO ₃ ) ₂ N as an alkali metal salt was added in the following composition C and added in the number of parts shown in Table 1 below.

Composition C
100 parts by weight of surface-modified colloidal silica (solid content concentration 40%, solvent: propylene glycol monomethyl ether acetate)
Dipentaerythritol hexaacrylate 48 parts by weight Tetrahydrofurfuryl acrylate 12 parts by weight Irgacure 184 3 parts by weight (polymerization initiator, manufactured by Ciba Specialty Chemicals)
40 parts by weight of propylene glycol monomethyl ether acetate (non-reactive diluent solvent)
Component (A1): Fluorine-containing block copolymer (Modiper F600 (manufactured by NOF Corporation) modified with isocyanate ethyl methacrylate (as solid content))
0.2 parts by weight (A2) component: Perfluoropolyether tetraacrylate (Fombrin Z-Tetraol (manufactured by Augmont)) having four terminal hydroxyl groups modified by acrylate (molecular weight Mw about 1,000)) 0.3 weight Part

(Measurement of half-life)
The half-life was measured according to JIS L 1094. Specifically, in a test room set at a temperature of 25 ° C. and a relative humidity of 10%, a sample cut out from each optical disk sample with a size of 35 × 35 mm was set in a measuring instrument, and the measurement time was up to 60 minutes. Followed the above measurement method. Table 2 below shows the results obtained by measuring the half-life in two ways, at the initial stage and after storage (temperature 80 ° C., relative humidity 85%, storage time 50 hours). The measurement result is obtained as the time (half life) until the withstand voltage of the sample decays to ½, and the shorter this time, the better the antistatic performance. In the case of the optical disk of the present invention, it is considered that there is no problem if the half life is 60 minutes or less in the above measurement.

  As can be seen from the results of Examples 1 to 6 in Table 2 above, even in an optical disc in which a hard coat layer having no antistatic performance is formed by adding an alkali metal salt to the light transmission layer, the initial and In both cases after storage, an excellent antistatic function is obtained. On the other hand, in Comparative Example 2 in which an alkali metal salt is added only to the hard coat layer, the initial antistatic function is good, but the result after storage is not preferable.

  For each optical disk sample, the contact angle was measured in two ways: initial and after storage (temperature 80 ° C., relative humidity 85%, storage time 50 hours). As a result, all contact angles were 105 °, and there was no difference between the initial results and the results after storage.

It is a schematic sectional drawing which shows an example of the laminated constitution of the optical disk of this invention. It is a schematic sectional drawing which shows the other example of the layer structure of the optical disk of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Light transmission layer 4 Hard coat layers 10 and 20 Optical disc 12 Phase change recording material layer 15 Reflective layer 16 Second dielectric layer 17 First dielectric layer

Claims (8)

  An optical disc comprising, on a substrate, at least an information layer, a light transmission layer, and a hard coat layer, and performing recording and / or reproduction by irradiating a laser beam from the hard coat layer side, wherein the light transmission layer comprises an ether An optical disc comprising a resin containing one or both of a bond and a urethane bond, and an alkali metal salt.   The optical disk according to claim 1, wherein the alkali metal salt is a lithium salt.   The optical disk according to claim 1, wherein the resin is a polyether group-containing urethane acrylate.   The optical disk according to claim 1, wherein the hard coat layer contains silica fine particles.   The optical disc according to any one of claims 1 to 4, wherein the hard coat layer contains one or both of a fluorine-containing block copolymer and a fluorine-containing polyether compound on the surface.   The optical disk according to any one of claims 1 to 5, wherein the content of the alkali metal salt is in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin.   The optical disk according to any one of claims 1 to 6, wherein recording and / or reproduction is performed using a laser beam having a wavelength of 380 to 450 nm in a recording / reproducing apparatus having an objective lens numerical aperture NA of 0.85 or more.   A resin layer and a hard coat layer are sequentially provided on the surface, and the resin layer contains a resin containing one or both of an ether bond and a urethane bond, and an alkali metal salt. An object.

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