JP4546986B2 - Sheet for manufacturing multilayer optical recording medium, multilayer structure for optical recording medium, and multilayer optical recording medium - Google Patents

Description

  The present invention relates to a multilayer optical recording medium in which optical recording layers and non-recording layers are alternately laminated, a multilayer optical recording medium manufacturing sheet used for manufacturing the multilayer optical recording medium, and a multilayer structure for optical recording media.

  In recent years, optical recording media have attracted attention because they can record a large amount of data and are used in various applications. Recently, a method for recording data three-dimensionally in order to further improve recording density, That is, a multilayer optical recording method has been proposed.

Conventionally, a multilayer optical recording medium for executing such a multilayer optical recording method has a problem that data crosstalk occurs between layers during recording and reproduction. In order to reduce such crosstalk, for example, an optical recording medium has been proposed in which a non-recording layer made of a material that does not record optical information is interposed between two or more recording layers (Patent Document). 1).
JP-A-11-250496

  However, when recording on the multilayer optical recording medium as described above, if the intensity of the laser beam is increased in order to increase the recording speed, the non-recording layer is damaged and deformed or altered, causing crosstalk or noise. There was a problem that occurred.

  The present invention has been made in view of such a situation, and a multilayer optical recording medium manufacturing sheet having a non-recording layer that is not easily damaged by a laser beam, a multilayer structure for an optical recording medium, and a multilayer optical recording medium The purpose is to provide.

  In order to achieve the above object, first, the present invention includes an optical recording layer containing a multiphoton absorbing dye, an adhesive that does not substantially contain a multiphoton absorbing dye and does not contain an aromatic compound. A non-recording layer having a non-recording layer is laminated to provide a multilayer optical recording medium manufacturing sheet.

  According to the above invention (invention 1), since the non-recording layer is hardly damaged by the laser beam, the difference between the laser recording threshold for the optical recording layer and the laser damage threshold for the non-recording layer is increased. be able to. That is, even if the intensity of the laser beam is increased in order to increase the recording speed, it is possible to suppress the occurrence of crosstalk and noise due to deformation or alteration of the non-recording layer.

  In the above invention (Invention 1), the non-recording layer is mainly composed of a (meth) acrylate (co) polymer and does not contain a crosslinking agent (Invention 2) or (meth) acrylate It is preferable to contain a (co) polymer as a main component and a crosslinking agent having no aromatic ring in the molecule.

  In the above invention (Invention 3), the crosslinking agent is at least one selected from the group consisting of an alicyclic isocyanate compound, an alicyclic epoxy compound, an aliphatic aziridine compound and a metal chelate compound. Preferably, it is an aliphatic aziridine compound (claim 5).

  In the said invention (Inventions 3-5), the compounding quantity of the said crosslinking agent is 0.1-5.0 mass parts (solid content) with respect to 100 mass parts (solid content) of (meth) acrylic acid ester (co) polymer ( The solid content is preferably part by mass (claim 6).

  Secondly, the present invention is formed by alternately laminating an optical recording layer containing a multiphoton absorbing dye and a non-recording layer substantially free of a multiphoton absorbing dye and containing no aromatic compound. A multilayer structure for optical recording media is provided (claim 7).

  Thirdly, the present invention comprises an optical recording layer containing a multiphoton absorbing dye and a non-recording layer containing substantially no multiphoton absorbing dye and not containing an aromatic compound. A multilayer optical recording medium provided with a multilayer structure is provided.

  According to the present invention, since the non-recording layer is not easily damaged by the laser beam, a multilayer optical recording medium with less occurrence of crosstalk and noise can be obtained.

Hereinafter, embodiments of the present invention will be described.
In the multilayer optical recording medium provided by the present invention, recording is performed by utilizing multiphoton absorption of the recording material. Multiphoton absorption is a phenomenon in which a compound is excited by simultaneously absorbing two or more photons. Since multiphoton absorption occurs only at a position where the light intensity is strong, the spatial resolution is improved and recording can be performed aiming at one point inside the medium. As a recording system using multiphoton absorption, the multiphoton absorbing dye itself may be due to structural change due to multiphoton absorption, or excitation energy obtained by multiphoton absorption is transferred to another compound, It may be by inducing a structural change.

[Sheet for optical recording medium production]
FIG. 1 is a cross-sectional view of a multilayer optical recording medium manufacturing sheet according to an embodiment of the present invention. A multilayer optical recording medium manufacturing sheet 1 according to this embodiment includes an optical recording layer 11, a non-recording layer 12 laminated on the optical recording layer 11, and a release sheet 13 laminated on the outer surface of the optical recording layer 11. And a release sheet 13 ′ laminated on the outer surface of the non-recording layer 12. However, the release sheets 13 and 13 ′ are peeled off when the multilayer optical recording medium manufacturing sheet 1 is used.

  The material constituting the optical recording layer 11 is not particularly limited as long as it contains a multiphoton absorbing dye, and an arbitrary material is appropriately selected from materials that are studied as a recording material using multiphoton absorption. Can be used. Among them, a material containing a two-photon absorption dye having a two-photon absorption cross-sectional area of 0.1 GM or more is preferable from the viewpoint of obtaining recording sensitivity sufficient for practical use, and a material containing a two-photon absorption dye of 100 GM or more is more preferable.

  The optical recording layer 11 may be composed of, for example, a multiphoton absorbing dye alone, or a multiphoton absorbing dye and other reactive compounds that are excited by the multiphoton absorption of the multiphoton absorbing dye and cause a chemical change. You may comprise by the material which mix | blended these with the matrix.

  The matrix may be an inorganic material or an organic material. However, from the viewpoints of easy manufacture of the multilayer optical recording medium manufacturing sheet 1 and many choices of materials, an organic polymer material is used. preferable. The polymer material may be a homopolymer or a copolymer, and there are no particular restrictions on the type of monomer, molecular weight, polymerization form, and the like.

  Specific examples of the polymer material include various polyethylenes, ethylene / 1-butene copolymers, ethylene-4-methyl-1-pentene copolymers, ethylene / 1-hexene copolymers, polypropylene, ethylene / propylene copolymers. Polymer, propylene / 1-butene copolymer, poly 1-butene, 1-butene / 4-methyl-1-pentene copolymer, poly-4-methyl-1-pentene, poly-3-methyl-1-butene, Polyolefins such as ethylene / cyclic olefin copolymer, cyclic olefin resin, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer or metal salt thereof, polymethyl methacrylate, alicyclic acrylic resin, etc. Polyester resins such as (meth) acrylate, polyethylene terephthalate, polyethylene naphthalate, etc. Fluorine resins such as fluoroethylene and perfluoroalkenyl vinyl ether polymers, polystyrene, polyvinyl alcohol, polycarbonate, polyphenylene sulfide, polyethersulfone, polyimide, polyphenylene oxide, olefin / N-substituted maleimide copolymers, allyl carbonate resins, epoxy acrylates Examples thereof include resins and urethane acrylate resins. These polymer materials may be used alone or in combination of two or more.

  On the other hand, the multiphoton absorption dye may be chemically bonded as a main chain or side chain component to the matrix, or may be simply dispersed or dissolved in the matrix. The multiphoton absorbing dye is not particularly limited. For example, a material that causes an isomerization reaction by light, such as an azo group, a C═C group, or a C═N group-containing compound; a (meth) acrylate compound, Materials that undergo a polymerization reaction by light; organic photochromic materials such as spiropyrans, spirooxazines, fulgides, diarylethenes, diisoindolylethenes; or phthalocyanine dyes, squalic acid dyes, azo dyes, perylene dyes, thiapyrylium dyes Quinacridone dye, azurenium dye, anthraquinone dye, fullerene derivative, carbazole derivative, dihaloanthreneone, epiindolidione, trihalopyrazylenedione, tetrahalothioindigo, benzothiazole derivative, oxazole derivative, hydrazone derivative, Norin derivatives, organic photorefractive material comprising a photoconductive organic compound such as fluorenone derivatives can be used.

  Although the compounding quantity of the multiphoton absorption pigment | dye with respect to a matrix is not restrict | limited in particular, It is preferable that it is 10-1000 mass parts with respect to 100 mass parts of matrices, and it is especially preferable that it is 10-500 mass parts.

  The thickness of the optical recording layer 11 is not particularly limited, but is usually about 0.05 to 10 μm, preferably 0.1 to 3.0 μm.

  The material constituting the non-recording layer 12 is a material that does not substantially contain a multiphoton absorbing dye and does not contain an aromatic compound and has adhesiveness. Since the non-recording layer 12 does not contain an aromatic compound, the non-recording layer 12 is hardly damaged by the laser beam, that is, hardly deformed or deteriorated. The reason is not necessarily clear, but it is considered that the aromatic compound is likely to cause multiphoton absorption. Therefore, the difference between the laser recording threshold for the optical recording layer 11 and the laser damage threshold for the non-recording layer 12 can be increased. That is, even if the intensity of the laser beam is increased in order to increase the recording speed, it is possible to suppress the occurrence of crosstalk and noise due to deformation or alteration of the non-recording layer 12.

  The non-recording layer 12 preferably has pressure-sensitive adhesiveness at the bonding temperature when producing the multilayer structure for optical recording media described later, and preferably has adhesiveness to the optical recording layer 11. As a material constituting such a non-recording layer 12, an acrylic pressure-sensitive adhesive is preferable, and (1) a (meth) acrylic acid ester (co) polymer as a main component and no cross-linking agent, and ( 2) Those containing a (meth) acrylic acid ester (co) polymer as a main component and a crosslinking agent having no aromatic ring in the molecule are preferred. Further, it is more preferable to contain a crosslinking agent for preventing bleeding of the non-recording layer 12 and maintaining the thickness accuracy with respect to the external force of the multilayer optical recording medium manufacturing sheet 1. That is, in (1) and (2) above, (2) is more preferable.

  The (meth) acrylic acid ester (co) polymer in (1) and (2) above is a (meth) acrylic acid ester having an alkyl group of 1 to 20 carbon atoms and a functional group having active hydrogen. Preferred is a copolymer of a monomer having the above and other monomers used as desired.

  Examples of the (meth) acrylic acid ester having 1 to 20 carbon atoms in the alkyl group of the ester moiety include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Butyl, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, (meth) acryl Examples include dodecyl acid, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. These may be used alone or in combination of two or more.

  Examples of monomers having a functional group having active hydrogen include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2 -(Meth) acrylic acid hydroxyalkyl esters such as hydroxybutyl, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, Acrylamides such as N-methylolacrylamide and N-methylolmethacrylamide; (meth) acrylic acid monomethylaminoethyl, (meth) acrylic acid monoethylaminoethyl, (meth) acrylic acid monomethylaminopropyl, (meth) acrylic acid mono (Meth) acrylic acid monoalkyl aminoalkyl such as chill aminopropyl, acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, ethylenically unsaturated carboxylic acids such as citraconic acid. These monomers may be used independently and may be used in combination of 2 or more type.

  Examples of other monomers optionally used include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; butadiene, Examples include diene monomers such as isoprene and chloroprene; nitrile monomers such as acrylonitrile and methacrylonitrile; N, N-dialkyl-substituted acrylamides such as N, N-dimethylacrylamide and N, N-dimethylmethacrylamide. These may be used alone or in combination of two or more.

  There is no restriction | limiting in particular about the copolymerization form of a (meth) acrylic acid ester (co) polymer, Any of a random, a block, and a graft copolymer may be sufficient. The molecular weight of the (meth) acrylic acid ester (co) polymer is preferably in the range of 300,000 to 2,000,000 in terms of weight average molecular weight (Mw). In addition, the said weight average molecular weight (Mw) is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  One (meth) acrylic acid ester (co) polymer may be used alone, or two or more may be used in combination.

  As a crosslinking agent used in the case of said (2), it is limited to the crosslinking agent which does not have an aromatic ring in a molecule | numerator. The crosslinking agent having no aromatic ring in the molecule is preferably an alicyclic isocyanate compound, an aliphatic isocyanate compound, an alicyclic epoxy compound, an aliphatic aziridine compound or a metal chelate compound, and particularly an aliphatic aziridine compound. Compounds are preferred. These may be used alone or in combination of two or more.

  Examples of the alicyclic isocyanate-based compounds include dicyclohexylmethane-4,4′-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, hydrogenated xylylene diisocyanate, and biurets thereof. Or a modified product such as an adduct that is a reaction product with a non-aromatic low-molecular active hydrogen-containing compound such as ethylene glycol, trimethylolpropane, or castor oil.

  Examples of the aliphatic isocyanate compound include hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and modified products thereof.

  Examples of the alicyclic epoxy compound include N, N′-diglycidylaminocyclohexane, diglycidylcyclohexanedicarboxylate, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, and the like. Of these, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane is preferred.

  Examples of the aliphatic aziridine compound include trimethylolpropane-β-aziridinylpropionate, tetramethylolmethanetri-β-aziridinylpropionate, trimethylolpropane tri-β- (2-methylaziridine). Examples include propionate and N, N′-hexamethylene-1,6-bis (1-aziridinecarboxylate), and trimethylolpropane-β-aziridinylpropionate is particularly preferable.

  Examples of the metal chelate compound include those having a metal atom of aluminum, zirconium, titanium, zinc, iron, tin, and the like, but an aluminum chelate compound is preferable from the viewpoint of performance.

  Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, monoisopropoxy aluminum mono-N-lauroyl-β-alanate monolauryl acetoacetate, aluminum trisacetylacetonate, monoacetylacetonate aluminum bis (isobutylacetate Acetate) chelate, monoacetylacetonate aluminum bis 2-ethylhexyl acetoacetate) chelate, monoacetylacetonate aluminum bis (dodecyl acetoacetate) chelate, monoacetylacetonate aluminum bis (oleyl acetoacetate) chelate, and the like.

  Examples of other metal chelate compounds include titanium tetrapropionate, titanium tetra-n-butyrate, titanium tetra-2-ethylhexanoate, zirconium-sec-butyrate, zirconium diethoxy-tert-butyrate, tri Examples include ethanolamine titanium dipropionate, ammonium lactate ammonium salt, and tetraoctylene glycol titanate.

  The amount of the crosslinking agent added to the (meth) acrylic acid ester (co) polymer is not particularly limited, but is 0.1 to 100 parts by mass (solid content) of the (meth) acrylic acid ester (co) polymer. 5.0 parts by mass (solid content) is preferable, and 0.1 to 1.0 parts by mass (solid content) is particularly preferable. When the addition amount of the crosslinking agent exceeds 5.0 parts by mass, there is a possibility that laser damage is likely to occur depending on the type of the crosslinking agent.

  The thickness of the non-recording layer 12 is not particularly limited, but is usually about 1 to 100 μm, preferably 2 to 50 μm.

  As the release sheets 13, 13 ′, conventionally known ones can be used. For example, a resin film such as polyethylene terephthalate or polypropylene, or a resin release film such as a silicone release agent, a long-chain alkyl release agent, or an alkyd resin. A release sheet subjected to a release treatment with a system release agent or the like can be used.

  In order to impart smoothness to the optical recording layer 11 or the non-recording layer 12, the release sheets 13 and 13 ′ have a surface roughness (Ra) on the side in contact with the optical recording layer 11 or the non-recording layer 12 of 0. It is preferably 1 μm or less, particularly 0.05 μm or less. When the surface roughness (Ra) of the release sheets 13 and 13 ′ exceeds 0.1 μm, the surface roughness of the optical recording layer 11 or the non-recording layer 12 increases, and the signal characteristics of the resulting multilayer optical recording medium deteriorate. There is a fear. The thickness of the release sheets 13 and 13 ′ is usually about 20 to 150 μm.

  Of the release sheets 13 and 13 ', it is preferable that the first release type is a light release type, and the later release type is a heavy release type. Further, one of the release sheets 13 and 13 ′ may be an untreated resin film and the other may be a release sheet.

  The multilayer optical recording medium manufacturing sheet 1 can be manufactured, for example, by the following method. First, a coating agent for the optical recording layer 11 containing the material constituting the optical recording layer 11 and, if desired, further containing a solvent is prepared, and the material constituting the non-recording layer 12 and optionally further containing a solvent. A coating agent for the non-recording layer 12 is prepared.

  And (1) After applying the coating agent for the optical recording layer 11 on the surface having the peelability of the release sheet 13 to form the optical recording layer 11, the coating agent for the non-recording layer 12 is coated thereon. Then, the non-recording layer 12 is formed, and the surface of the non-recording layer 12 is laminated with a peelable surface of the other release sheet 13 ', or (2) a coating agent for the non-recording layer 12 Is applied to the surface of the release sheet 13 'having a peelability to form the non-recording layer 12, and then the optical recording layer 11 is formed by applying a coating agent for the optical recording layer 11 thereon. The surface having the peelability of another release sheet 13 is stacked on the surface of the recording layer 11 or (3) the coating agent for the optical recording layer 11 is applied on the peelable surface of the release sheet 13. Thus, the optical recording layer 11 is formed, while the coating agent for the non-recording layer 12 has the peelability of the release sheet 13 ′. Was applied on top to form a non-recording layer 12 is laminated both as the optical recording layer 11 and the non-recording layer 12 is overlaid. For the coating of the coating agent, for example, a coating machine such as a kiss roll coater, a reverse roll coater, a knife coater, a roll knife coater, or a die coater can be used.

  The sheet 1 for producing a multilayer optical recording medium obtained as described above is suitably used as a multilayer structure for an optical recording medium described below or a material for producing a multilayer optical recording medium.

[Multi-layer structure for optical recording media]
The multilayer structure for an optical recording medium according to this embodiment is a structure in which optical recording layers 11 and non-recording layers 12 are alternately laminated, which is formed using the multilayer optical recording medium manufacturing sheet 1 described above. Yes (see symbol 2 in FIG. 2).

  The number of stacked layers of the optical recording layer 11 and the non-recording layer 12 is not particularly limited, but is usually about 2 to 500 layers, preferably 5 to 200 layers. A single layer cannot provide a sufficient recording density, and if it exceeds 500 layers, there may be a problem in writing or reading information due to absorption of light in each layer or reflection of light between layers.

  The total thickness of the optical recording layer 11 and the non-recording layer 12 (the thickness of the multilayer structure for an optical recording medium) is usually about 10 μm to 5 mm, preferably 20 μm to 2 mm, more preferably 50 μm to 1.2 mm. .

  This multilayer structure for an optical recording medium may be manufactured during the manufacturing process of the multilayer optical recording medium 10 as will be described later, or may be manufactured in advance prior to the manufacturing of the multilayer optical recording medium 10.

[Manufacture of multilayer optical recording media]
Next, an example of a method for manufacturing the multilayer optical recording medium 10 using the multilayer optical recording medium manufacturing sheet 1 will be described. FIG. 2 is a cross-sectional view of the resulting multilayer optical recording medium 10.

  First, a substrate 3 made of polycarbonate resin or the like is prepared, and an adhesive layer 4 is formed thereon. The material of the adhesive layer 4 may be the same as or different from the adhesive material constituting the non-recording layer 12.

  Then, the release sheet 13 is peeled off from the multilayer optical recording medium manufacturing sheet 1, and the exposed optical recording layer 11 and the pressure-sensitive adhesive layer 4 on the substrate 3 face each other and are bonded together. Next, the release sheet 13 ′ is peeled off from this laminate to expose the non-recording layer 12, and the non-recording layer 12 and the release sheet 13 are peeled off from another multilayer optical recording medium manufacturing sheet 1 to expose the optical recording. The layers 11 are joined so that they face each other. Thereafter, the multilayer structure 2 for an optical recording medium in which n layers of the optical recording layer 11 and the non-recording layer 12 are laminated is obtained by sequentially repeating the lamination in the same procedure.

  Finally, the multi-layer optical recording medium 10 is obtained by attaching the light-transmitting protective film 5 to the non-recording layer 12 exposed by peeling off the uppermost release sheet 13 ′. The light-transmitting protective film is not particularly limited, and can be appropriately selected from those conventionally used as protective films for optical recording media. The thickness of the light-transmitting protective film is not particularly limited, but is usually about 20 to 600 μm, preferably 20 to 150 μm.

  As another example of the manufacturing method of the multilayer optical recording medium 10, the substrate 3 is prepared, the release sheet 13 ′ is peeled off from the multilayer optical recording medium manufacturing sheet 1, the exposed non-recording layer 12, the surface of the substrate 3, So that they face each other. Next, the release sheet 13 is peeled off from the laminate to expose the optical recording layer 11, and the release sheet 13 ′ is peeled off from the optical recording layer 11 and another multilayer optical recording medium manufacturing sheet 1 to expose the non-recording. The layers 12 are joined so that they face each other. The multilayer structure 2 for an optical recording medium in which n layers of the non-recording layer 12 and the optical recording layer 11 are laminated is obtained by sequentially repeating the lamination in the same procedure. Finally, a light-transmitting protective film with an adhesive layer is attached to the optical recording layer 11 exposed by peeling off the uppermost release sheet 13 to obtain the multilayer optical recording medium 10.

  In the multilayer optical recording medium 10 obtained as described above, since the non-recording layer 12 is not easily damaged by the laser beam, even if the intensity of the laser beam is increased to increase the recording speed, the non-recording layer 12 There is little occurrence of crosstalk and noise due to 12 deformations and alterations.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, the release sheet 13 or the release sheet 13 ′ in the multilayer optical recording medium manufacturing sheet 1 may be omitted.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
(1) Formation of optical recording layer 100 parts by mass of polymethylmethacrylate, 10 parts by mass of 1,3,3-trimethylindolino-6′-nitrobenzopyrospirane as a photochromic material, 500 parts by mass of ethyl acetate and 490 parts by mass of toluene Parts were mixed to prepare a coating solution having a solid content of 10% by mass.

  The coating liquid was applied to one side of a 40 μm thick polypropylene film as a release sheet by a gravure coating method and dried at 90 ° C. for 1 minute to form an optical recording layer having a thickness of 1.5 μm.

(2) Formation of non-recording layer 30 parts by mass of an n-butyl acrylate polymer (BA; Mw = 500,000) was dissolved in 100 parts by mass of ethyl acetate to prepare a coating solution having a solid content concentration of 30% by mass.

  The above coating solution was applied with a knife coater to the release layer surface of a release sheet comprising a silicone release layer on one side of a 38 μm thick polyethylene terephthalate film, and dried by heating at 90 ° C. for 1 minute. A non-recording layer of 0 μm was formed.

(3) Production of sheet for producing multilayer optical recording medium By combining the non-recording layer surface after drying formed in (2) above with the optical recording layer surface formed in (1) above, and pressing with two rubber rolls Twenty sheets for producing a multilayer optical recording medium in which an optical recording layer and a non-recording layer were laminated were produced.

(4) Production of multilayer optical recording medium A non-recording layer having a thickness of 8.0 μm is formed on one side of a 75 μm-thick polycarbonate substrate (manufactured by Teijin Kasei Co., Ltd.) using the same material as the coating liquid in (2) above. Provided. And from the sheet | seat for multilayer optical recording medium manufacture obtained by said (3), the optical recording layer which peeled and exposed the polypropylene film and the non-recording layer of the said polycarbonate substrate were match | combined, and it pressure-bonded with two rubber rolls. . Next, the polyethylene terephthalate film was peeled from the laminate, and the exposed non-recording layer surface was combined with the optical recording layer surface of another multilayer optical recording medium-producing sheet from which the polypropylene film was peeled off, and pressed with two rubber rolls. Lamination was sequentially repeated in the same procedure to produce a multilayer structure having 20 optical recording layers (see FIG. 2). The thickness of this multilayer structure was 270 μm. Finally, the uppermost polyethylene terephthalate film was peeled off and a protective film 75 μm thick polycarbonate film was attached to obtain a multilayer optical recording medium.

[Example 2]
30 parts by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) is dissolved in 100 parts by mass of ethyl acetate, and the solid content concentration is 30% by mass. A coating solution for the recording layer was prepared. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

Example 3
Dicyclohexylmethane with respect to 100 parts by mass of an ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) in solid content concentration Add 0.2 parts by mass of an alicyclic isocyanate-based crosslinking agent composed of -4,4'-diisocyanate (manufactured by Wako Pure Chemical Industries, Ltd., dicyclohexylmethane-4,4'-diisocyanate, solid content concentration 100% by mass), and uniformly The mixture was stirred until it became a coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

Example 4
For 100 parts by mass of an ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) in terms of solid content, Add 0.2 parts by mass of an alicyclic epoxy-based crosslinking agent (Mitsubishi Gas Chemical Co., Ltd., Tetrad C, solid content concentration: 100% by mass) composed of 3-bis (N, N′-diglycidylaminomethyl) cyclohexane, and uniformly The mixture was stirred until it became a coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

Example 5
Trimethylol with respect to 100 parts by mass of an ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) in solid content concentration Aliphatic aziridine crosslinker (Nippon Shokubai Co., Ltd., Chemite) consisting of propenetri-β-aziridinylpropionate (also known as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate]) 4.0 parts by mass of PZ-33) diluted to 5% by mass was added and stirred until uniform, and this was used as the coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

Example 6
Aluminum tris with respect to 100 parts by mass of an ethyl acetate solution containing 30% by mass of solid content concentration of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000). Add 4.0 parts by mass of an aluminum chelate cross-linking agent composed of acetylacetonate (manufactured by Soken Chemical Co., Ltd., M-5A, solid content concentration 5% by mass), stir until uniform, and apply this to the coating for the non-recording layer Liquid. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Comparative Example 1]
Tolylene dihydrate with respect to 100 parts by mass of an ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) in solid content concentration 0.53 parts by mass of an isocyanate-based crosslinking agent (manufactured by Toyo Ink Manufacturing Co., Ltd., BHS8515, solid concentration 37.5% by mass) was added and stirred until uniform, and this was used as a coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Comparative Example 2]
For 100 parts by mass of an ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000) in terms of solid content, Add 0.2 parts by mass of an aromatic epoxy crosslinking agent (Mitsubishi Gas Chemical Co., Ltd., Tetrad X, solid content concentration: 100% by mass) comprising 3-bis (N, N′-diglycidylaminomethyl) xylylene, and uniformly The mixture was stirred until it became a coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Comparative Example 3]
Aluminum tris with respect to 100 parts by mass of an ethyl acetate solution containing 30% by mass of solid content concentration of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000). 4.0 parts by mass of an aluminum chelate cross-linking agent composed of acetylacetonate (manufactured by Soken Chemical Co., Ltd., M-5A, solid content concentration 5 mass%), and a styrene copolymer (manufactured by Mitsui Chemicals, FTR) as a tackifier -6100, white flakes, solid content concentration of 100% by mass) and 10 parts by mass were stirred until uniform, and this was used as the coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Comparative Example 4]
Ethyl acetate solution containing 30% by mass of n-butyl acrylate (BA) / phenoxyethyl acrylate (PEA) / acrylic acid (AA) copolymer (composition mass ratio 50/47/3; Mw = 500,000) in solid content concentration To 100 parts by mass, add 4.0 parts by mass of an aluminum chelate cross-linking agent made of aluminum trisacetylacetonate (manufactured by Soken Chemical Co., Ltd., M-5A, solid content concentration 5% by mass), and stir until uniform. This was used as a coating solution for the non-recording layer. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Comparative Example 5]
For 100 parts by mass of an ethyl acetate solution containing 30% by mass of solid content concentration of n-butyl acrylate (BA) / acrylic acid (AA) copolymer (composition mass ratio 97/3; Mw = 600,000), xylylene diene Add 0.27 parts by mass of an isocyanate-based isocyanate crosslinking agent (manufactured by Soken Chemical Co., Ltd., TD-75, solid content concentration: 75% by mass), stir until uniform, and coat this for a non-recording layer Liquid. A multilayer optical recording medium manufacturing sheet and a multilayer optical recording medium were produced in the same manner as in Example 1 except that the non-recording layer was formed using this coating solution.

[Test example]
The coating solution for the non-recording layer prepared in Examples or Comparative Examples was applied on the release film with a knife coater and dried by heating at 90 ° C. for 1 minute to form a 20 μm thick non-recording layer. The non-recording layer was placed on a slide glass and pressed with two rubber rolls, and then the release film was peeled off. On the other hand, an aqueous solution of polyvinyl alcohol (PVA: partially saponified product, degree of polymerization of about 500) was coated on a release film with a knife coater and dried by heating at 110 ° C. for 1 minute to form a PVA layer having a thickness of about 5 μm. Prepared. And the said PVA layer was piled up on the said non-recording layer, it crimped | bonded by two rubber rolls, the peeling film was peeled after that, and what was obtained was used as the sample.

  Laser irradiation was performed on the non-recording layer of the sample using an optical system using a titanium sapphire femtosecond laser (wavelength 760 nm) as a light source. The average intensity of the laser was changed to 50 mW, 40 mW, 30 mW, 20 mW, and 10 mW, and the irradiation time was set to 1/2 second.

  A confocal optical system using a He—Ne laser (wavelength: 633 nm) as a light source is used to observe the irradiated portion of the laser beam, and the laser intensity value at which the irradiated portion cannot be observed as a bit mark is defined as a laser damage threshold value. did. The results are shown in Table 1.

  As apparent from Table 1, the non-recording layer containing no aromatic compound had a significantly larger laser damage threshold than the non-recording layer containing the aromatic compound.

  The present invention is useful for producing a multilayer optical recording medium with little occurrence of crosstalk and noise.

It is sectional drawing of the sheet | seat for multilayer optical recording medium manufacture which concerns on one Embodiment of this invention. 1 is a cross-sectional view of a multilayer optical recording medium according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sheet | seat for multilayer optical recording medium manufacture 11 ... Optical recording layer 12 ... Non-recording layer 13, 13 '... Release sheet 2 ... Multilayer structure 3 for optical recording media ... Substrate 4 ... Adhesive layer 5 ... Light-transmitting protective film 10 ... Multilayer optical recording medium

Claims (8)

An optical recording layer containing a multiphoton absorbing dye;
A sheet for producing a multilayer optical recording medium, comprising: a non-recording layer having substantially no multiphoton absorption dye and not containing an aromatic compound and having an adhesive property.   2. The sheet for producing a multilayer optical recording medium according to claim 1, wherein the non-recording layer comprises a (meth) acrylic acid ester (co) polymer as a main component and does not contain a crosslinking agent.   2. The multilayer optical recording medium according to claim 1, wherein the non-recording layer contains a (meth) acrylic acid ester (co) polymer as a main component and a crosslinking agent having no aromatic ring in the molecule. Production sheet.   The said crosslinking agent is at least 1 sort (s) chosen from the group which consists of an alicyclic isocyanate type compound, an alicyclic epoxy type compound, an aliphatic aziridine type compound, and a metal chelate compound. A sheet for producing a multilayer optical recording medium.   4. The multilayer optical recording medium manufacturing sheet according to claim 3, wherein the crosslinking agent is an aliphatic aziridine compound.   The blending amount of the crosslinking agent is 0.1 to 5.0 parts by mass (solid content) with respect to 100 parts by mass (solid content) of a (meth) acrylic acid ester (co) polymer. Item 6. The sheet for producing a multilayer optical recording medium according to any one of Items 3 to 5. An optical recording layer containing a multiphoton absorbing dye;
A multilayer structure for an optical recording medium, which is formed by alternately laminating non-recording layers which do not substantially contain a multiphoton absorbing dye and do not contain an aromatic compound. An optical recording layer containing a multiphoton absorbing dye;
A multilayer optical recording medium comprising a multilayer structure in which a multi-photon absorbing dye is not substantially contained and non-recording layers not containing an aromatic compound are alternately laminated.

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