JP2013010954A - Active energy ray-curing resin composition, and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active energy ray-curing resin composition suitable for production of an optical recording medium exhibiting low warpage, and to provide an article and an optical recording medium exhibiting low warpage.SOLUTION: The active energy ray-curing resin composition contains: 100 pts.mass of a polymer component containing 5 to 50 mass% of an acrylic polymer (A) having a mass-average molecular weight of 3,000 to 30,000 and 50 to 95 mass% of a radically polymerizable compound (B); and 1 to 20 pts.mass of a photopolymerization initiator (C), wherein the radically polymerizable compound (B) contains a (b-1) component being a compound having two or more (meth)acryloyl groups in one molecule thereof. There are provided an article having a layer composed of a cured material of the composition on a metal, an optical recording medium having the layer, an article having a coated layer of the composition on a substrate and an optical recording medium having a coated layer of the composition on a substrate.

Description

  The present invention relates to an optical recording medium such as a read-only optical disk and a recordable optical disk used as a Blu-ray disc, for example. The present invention also relates to an active energy ray-curable resin composition that can be used to form a light transmission layer of an optical recording medium.

  In recent years, various researches on density increase have been made in the field of information recording media. As digital high-definition broadcasting spreads, the demand for large-capacity optical recording media is increasing. For example, a large-capacity optical disc such as a Blu-ray disc has been put into practical use and is about to become popular.

  The Blu-ray disc has a light transmission layer on the information recording surface of the support substrate on which the information recording surface is formed. As a method for forming this light transmissive layer, a method has been developed in which a liquid UV curable resin composition is applied by spin coating and then cured by irradiation with active energy rays to form a light transmissive layer (patent) Reference 1).

  As a liquid ultraviolet curable resin composition used in this method, for example, a composition containing urethane acrylate is known (Patent Document 2). However, a cured product obtained by curing such a liquid ultraviolet curable resin composition containing urethane acrylate is good with small warpage, but is relatively soft and has room for improvement in terms of hardness.

JP 2003-85836 A JP 2002-230831 A

  The present invention has been made in order to solve the above-mentioned problems of the liquid ultraviolet curable resin composition, and is an optical recording medium on which a light transmission layer is formed. The warp is small (hereinafter referred to as low warpage property). It is an object to provide an optical recording medium having a light-transmitting layer with high hardness.

  Another object of the present invention is to provide an article having low warpage and high hardness.

  Furthermore, an object of the present invention is to provide an active energy ray-curable resin composition suitable for forming the light transmission layer of the optical recording medium as described above.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have determined that the acrylic polymer (A) having a mass average molecular weight of 3000 to 30000 (hereinafter referred to as component (A)) and the radical polymerizable compound (B) {hereinafter, (B) component} containing a specific ratio, and a photopolymerization initiator (C) {hereinafter referred to as (C) component} in a specific amount, and (B) two or more ( An active energy ray-curable resin composition (hereinafter referred to as a resin composition) containing the component (b-1) {hereinafter referred to as the component (b-1)}, which is a compound having a (meth) acryloyl group, has low warpage and It was found to be excellent in hardness. Here, the acrylic polymer means a compound obtained by radical polymerization of a (meth) acryloyl group.

In the first aspect, the present invention relates to an active energy comprising (A) component 5 to 50% by mass and (B) polymer component 100% by mass containing 50 to 95% by mass, and (C) component 1 to 20 parts by mass. A wire curable resin composition,
The component (B) relates to an active energy ray-curable resin composition containing the component (b-1).

In a second aspect, the present invention relates to the active energy ray-curable resin composition according to the first aspect, wherein the component (A) is an acrylic polymer having a structure represented by the formula (1).


In the formula (1), R represents any one of a substituted or unsubstituted alkyl group, cycloalkyl group, and aryl group. Moreover, a substituent shows either an epoxy group, a hydroxy group, a cyano group, an amino group, and a carboxyl group.

  In the third aspect, the present invention relates to the active energy ray-curable type according to the first or second aspect, which comprises a compound having 2 or 3 (meth) acryloyl groups in one molecule as the component (b-1). The present invention relates to a resin composition.

  In the fourth aspect, the present invention provides (b-2) component {hereinafter referred to as (b-2) component}, which is a compound having one (meth) acryloyl group in one molecule as component (B). The active energy ray curable resin composition of any one of the 1st-3rd aspect containing this.

  In a fifth aspect, the present invention relates to the active energy ray-curable resin composition according to any one of the first to fourth aspects, wherein the content of the organic solvent is 1% by mass or less.

  In a sixth aspect, the present invention relates to the active energy ray-curable resin composition according to any one of the first to fifth aspects, wherein the glass transition temperature of component (A) is 50 ° C. or higher.

  In a seventh aspect, the present invention provides biphenol A di (meth) acrylate modified with 4 to 6 alkylene oxides per molecule, tricyclodecane dimethanol di (meth) acrylate, as component (b-1), Any one of the first to sixth embodiments, including any of neopentyl glycol-modified trimethylolpropane di (meth) acrylate and trimethylolpropane tri (meth) acrylate modified with 3 to 6 alkylene oxides per molecule To an active energy ray-curable resin composition.

  In an eighth aspect, the present invention relates to an article having a layer made of a cured product of the active energy ray-curable resin composition in any one of the first to seventh aspects on a metal.

  In a ninth aspect, the present invention relates to an optical recording medium having a layer comprising a cured product of the active energy ray-curable resin composition according to any one of the first to seventh aspects.

  According to the present invention, it is possible to provide an optical recording medium on which a light transmission layer is formed, which has a light transmission layer with low warpage and high hardness.

  In addition, according to the present invention, an article having low warpage and high hardness can be provided.

  Furthermore, according to the present invention, an active energy ray-curable resin composition suitable for forming the light transmission layer of the optical recording medium as described above can be provided.

  The active energy ray-curable resin composition of the present invention is a radical curable resin composition containing a component (A), a component (B), and a component (C). Here, the total amount of the component (A), the component (B) and the component (C) is 90% by mass or more of the solid content which is a component obtained by removing the organic solvent from the active energy ray-curable resin composition. preferable. In addition, the active energy ray-curable resin composition may be a solventless system in which the content of the organic solvent is 1% by mass or less from the viewpoint of reducing the volatile organic solvent and reducing the environmental load by recycling the resin composition. preferable.

-(A) component (A) component is a component which improves low curvature property by reducing cure shrinkage. (A) The mass mean molecular weight of a component is 3000-30000 in polystyrene conversion of a gel permeation column chromatography, and 3000-20000 are preferable. Moreover, 3000-10000 are more preferable. When the mass average molecular weight of the component (A) is 3000 or more, the low warpage of the cured product is improved. When the mass average molecular weight is 30000 or less, the viscosity of the active energy ray-curable resin composition is lowered, and workability is improved. Further, when the mass average molecular weight is 20000 or less, the workability is further improved.
Moreover, it is preferable that the glass transition temperature of (A) component is 50 degreeC or more from a high-temperature, high-humidity viewpoint of the hardened | cured material obtained by hardening a resin composition. The glass transition temperature can be obtained from a DSC curve obtained by differential scanning calorimetry, and the straight line obtained by extending the low temperature side base line to the high temperature side and the curve gradient of the stepped portion of the glass transition are maximized. The temperature at the intersection with the tangent drawn at such a point (extrapolated glass transition start temperature) was defined as the glass transition temperature.

  As the (meth) acrylic acid ester which is a raw material for constituting the component (A), for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, (meth) acrylic Isopropyl acid, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate and (meth) acrylic Examples include acid n-hexyl, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and phenyl (meth) acrylate. These can be used individually by 1 type, or can use 2 or more types together, and can also use a copolymer as (A) component. By changing the copolymer composition, the component (A), and thus the resin composition, can be adjusted to desired physical properties. For example, in order to increase the hardness of the cured product of the resin composition, (meth) having a high glass transition temperature such as methyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentenyl (meth) acrylate. It is preferable to increase the copolymerization ratio of the acrylate ester. In order to improve the compatibility with the component (B), methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (meth) acrylic Increasing the copolymerization ratio of (meth) acrylic acid ester having a short chain alkyl group such as n-butyl acid, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, and t-butyl (meth) acrylate It is preferable.

  (Meth) acrylic acid esters are described in, for example, “UV / EB Curing Handbook—Raw Materials (1985, Polymer Press Society)” and the like as (A) component raw materials. Acid esters can be appropriately selected and used. In the present invention, “(meth) acryl” means “acryl” or “methacryl”.

  Examples of the polymerization method for obtaining the component (A) include a solution polymerization method, a suspension polymerization method, and an emulsion polymerization, and a desired polymerization initiator, chain transfer agent, solid content, or reaction conditions can be adjusted. A polymer can be obtained.

  From the viewpoint of reducing environmental burden, there is an increasing demand for solvent-free resin compositions having an organic solvent content of 1% by mass or less. As a polymerization method for obtaining the component (A), it is preferable that the component (A) is in the form of solid particles not containing an organic solvent when used in a solvent-free active energy ray-curable resin composition. Is preferably a suspension polymerization method.

  As the suspension polymerization method for obtaining the component (A), for example, a polymerization initiator is added to an aqueous suspension containing water, a dispersant and a monomer, and then the polymerization initiator-containing aqueous suspension is heated. Then, the polymerization is carried out, and then the aqueous suspension after polymerization is filtered, washed, dehydrated and dried.

  Examples of the dispersant include poly (meth) acrylic acid alkali metal salts, alkali metal salts of copolymers of (meth) acrylic acid and methyl (meth) acrylate, and polyvinyl alcohol having a saponification degree of 70 to 100%. -Methyl and methylcellulose. These can be used alone or in combination of two or more.

  The amount of the dispersant added in the aqueous suspension polymerization is a monomer 100 to be polymerized in view of dispersion stability in suspension polymerization and washing, dehydrating, drying and fluidity of the resulting granular polymer. It can be about 0.005-5 mass parts per mass part, and 0.01-1 mass part is preferable.

  For the purpose of improving the dispersion stability of aqueous suspension polymerization, an electrolyte such as sodium carbonate, sodium sulfate or manganese sulfate can be used in aqueous suspension polymerization.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvalero). Azo compounds such as nitrile); benzoyl peroxide, lauroyl peroxide, t-butylperoxy 2-ethylhexanoate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl Organic peroxides such as peroxy 2-ethylhexanoate and t-hexyl hydroperoxide; inorganic peroxides such as hydrogen peroxide, sodium persulfate, and ammonium persulfate. These can be used alone or in combination of two or more.

  In order to adjust the molecular weight of the component (A), a chain transfer agent can be used. Examples of chain transfer agents include mercaptans such as n-dodecyl mercaptan, thioglycolic acid esters such as octyl thioglycolate, cobalt complexes such as bis (borondifluorodiphenylglyoxymate) cobalt (II), α-methylstyrene dimer, and the like. Tarpinolene is mentioned. These can be used alone or in combination of two or more. Among these, a transition metal complex is preferable and a cobalt complex is more preferable in that it has less odor and hardly corrodes metals. According to JP-A-11-124486, when a transition metal complex is used as a chain transfer agent, it is known that the obtained polymer has the structure of the above formula (1). In the present invention, it is preferable to use the component (A) having the structure of the above formula (1) produced using a transition metal complex, since a compound having an appropriate mass average molecular weight can be obtained.

  Examples of the cobalt complex include Japanese Patent No. 3585730, Japanese Patent Publication No. 6-23209, Japanese Patent Publication No. 7-35411, US Pat. No. 4,269,945, US Pat. No. 4,694,054, US Pat. No. 4,837,326, US Pat. And those described in JP-A-9-510499 and the like can be used.

  Specifically, bis (borondifluorodimethyldioxyiminocyclohexane) cobalt (II), bis (borondifluorodimethylglyoxymate) cobalt (II), bis (borondifluorodiphenylglyoxymate) cobalt (II), vicinal Cobalt (II) complex of iminohydroxyimino compound, cobalt (II) complex of tetraazatetraalkylcyclotetradecatetraene, N, N′-bis (salicylidene) ethylenediaminocobalt (II) complex, dialkyldiazadioxodialkyldodeca Examples thereof include cobalt (II) complexes of dienes and cobalt (II) porphyrin complexes.

  One or more of these can be appropriately selected and used. Among these, bis (borondifluorodiphenylglyoxymate) cobalt (II) that is stably present in an aqueous medium and has a high chain transfer effect is particularly preferable.

  As an addition amount of a chain transfer agent, 0.001-10 mass parts is preferable with respect to 100 mass parts of monomers which are the raw materials for comprising (A) component, and 0.05-5 mass parts is more preferable. . When the addition amount of the chain transfer agent is 0.001 part by mass or more, the molecular weight of the copolymer can be reduced by chain transfer of radicals, and the molecular weight can be further reduced by increasing the addition amount of the chain transfer agent. it can. Moreover, the addition amount of a chain transfer agent can be 10 mass parts or less, the residual amount of an unreacted monomer and a chain transfer agent can be suppressed, and the odor of (A) component can be suppressed.

  The aqueous suspension polymerization temperature is preferably from 50 to 130 ° C, more preferably from 60 to 100 ° C, from the viewpoint of polymerization in a short time and polymerization stability.

  The proportion of component (A) used in the resin composition is based on the total amount of component (A) and component (B) (that is, when the sum of component (A) and component (B) is 100% by mass), 5 It is in the range of ˜50% by mass. The lower limit is preferably 10% by mass or more, and the upper limit is preferably 40% by mass or less. When the amount of the component (A) is 5% by mass or more, the low warpage of the cured product is improved. Moreover, when it is 50 mass% or less, the viscosity of a resin composition becomes low and coating workability | operativity becomes good.

-(B) component The active energy ray hardening-type resin composition of this invention contains (B) component which is a radically polymerizable compound, and (b-1) component is used as (B) component. The resin composition may contain only the component (b-1) as the component (B), or may contain the component (b-2) in addition to the component (b-1). The radical polymerizable compound is a compound that causes a polymerization reaction by radicals.

  (B-1) A component is a component which raises the hardness of hardened | cured material by bridge | crosslinking the hardened | cured material of a resin composition. Moreover, it is a component which suppresses appearance abnormality, such as wrinkles of hardened | cured material.

  The component (b-1) has two or more (meth) acryloyl groups in one molecule. From the viewpoint of low warpage, the number of (meth) acryloyl groups in one molecule is preferably 6 or less, and more preferably 3 or less.

  Specific examples of the component (b-1) include hydroxypivalate neopentyl glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Modified with polypropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, bis (2-acryloyloxyethyl) -2-hydroxyethyl isocyanurate, ethylene oxide Bisphenol A di (meth) acrylate, bisphenol A di (meth) acrylate modified with propylene oxide, 1,6-hexanediol di (meth) acrylate, trimethylol Lopantri (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate modified with ethylene oxide, trimethylolpropane tri (meth) acrylate modified with propylene oxide, ditri Methylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tetra (meth) acrylate, tris (2- (Acryloyloxyethyl) isocyanurate, dipentaerythritol penta (meth) acrylate, dipentaerythritol Hexa (meth) acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These can also be used individually by 1 type and can also use 2 or more types together.

  The component (b-1) preferably contains a compound having 2 or 3 (meth) acryloyl groups in one molecule, and 4 to 6 per molecule from the viewpoint of the balance between hardness and low warpage. Bisphenol A di (meth) acrylate modified with 1 alkylene oxide, tricyclodecane dimethanol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, 3-6 alkylene oxides per molecule Modified with trimethylolpropane tri (meth) acrylate, preferably bisphenol A di (meth) acrylate modified with 4-6 ethylene oxide per molecule, modified with 4-6 propylene oxide per molecule Bisphenol A di (meth) acrylate, tri Chlodecane dimethanol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate modified with 3-6 ethylene oxide per molecule, and per molecule Trimethylolpropane tri (meth) acrylate modified with 3 to 6 propylene oxides is particularly preferred.

  The use ratio of the component (b-1) is preferably in the range of 20 to 90% by mass based on the total amount of the component (A) and the component (B). The lower limit is more preferably 25% by mass or more. The upper limit is more preferably 70% by mass or less. When the amount of the component (b-1) is 20% by mass or more, the hardness of the cured product and the appearance (smoothness) of the cured product are improved. Moreover, when it is 90 mass% or less, the low curvature property of hardened | cured material becomes better.

  The component (B) preferably contains a compound having one (meth) acryloyl group in one molecule as the component (b-2). This is a dilution component that lowers the viscosity of the resin composition. For example, tetrahydrofurfuryl (meth) acrylate, 2-ethyl-hexyl (meth) acrylate, 2-ethyl-2-methyl-1,3-dioxolane-4 -Il-methyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, caprolactone modified phosphoric acid (meth) acrylate , Phenoxyethyl (meth) acrylate, phenyldiethylene glycol (meth) acrylate, nonylphenyloxyethyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) Acrylate and the like.

  Among these, tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, and 2-ethyl-2-methyl-1,3-dioxolan-4-yl-methyl (meth) acrylate are preferable from the viewpoint of dilutability. preferable.

  The use ratio of the component (B) in the resin composition is in the range of 50 to 95% by mass based on the total amount of the component (A) and the component (B). The lower limit is preferably 60% by mass or more, and the upper limit is preferably 90% by mass or less. (B) When the quantity of a component is 50 mass% or more, the viscosity of a resin composition becomes low and coating workability | operativity improves. Moreover, when it is 95 mass% or less, the low curvature property of hardened | cured material becomes good.

-(C) component A (C) component is a photoinitiator and is a component for making an active energy ray hardening-type resin composition harden | cure efficiently by active energy irradiation. Specific examples of the component (C) include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, methylorthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, diethoxyacetophenone 2-hydroxy-2-methyl-1-phenylpropan-1-one, oligo {2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone}, benzyldimethyl ketal, 1- Hydroxycyclohexyl-phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2- N-di-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, diethylthioxanthone, isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2, 4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] Phenyl} -2-methylpropan-1-one and methylbenzoylformate.

  Among these, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl-phenyl ketone are preferable from the viewpoints of curability of the resin composition and hard yellowing of the cured product.

  From the viewpoint of curability in the air atmosphere of the active energy ray-curable resin composition, the use ratio of the component (C) in the resin composition is based on a total of 100 parts by mass of the component (A) and the component (B). It shall be in the range of 1-20 mass parts. The lower limit is more preferably 3 parts by mass or more, and the upper limit is more preferably 10 parts by mass or less. When the amount of component (C) is 1 part by mass or more, curability is improved. Moreover, in the case of 20 mass parts or less, hardened | cured material is hard to yellow.

-Others As long as the effects of the present invention are not impaired, other components in the active energy ray-curable resin composition, such as antifouling agents, slip agents, adhesion promoters, thermal polymerization initiators, antioxidants and light Known additives such as a stabilizer, a photosensitizer, a thermoplastic resin, a leveling agent, an ultraviolet absorber, a polymerization inhibitor, an inorganic filler, an organic filler, and a surface organically treated inorganic filler can be appropriately blended.

  When the active energy ray-curable resin composition is used for the light transmission layer of the optical recording medium, it is 5 μm or more, preferably 1 μm or more in order to prevent reading or writing errors due to the presence of foreign matters such as dust and gel. It is preferable to perform filtration using a filtration filter that can remove foreign matters.

  Examples of the material for the filtration filter include cellulose, polyethylene, polypropylene, polytetrafluoroethylene, and nylon.

  The resin composition of the present invention can be applied to metal, glass, ceramics, paper, wood, plastic, and the like, but is a particularly suitable material when applied on metal. Examples of the metal include gold, silver, copper, iron, palladium, indium, tellurium, tin, zinc, yttrium, cerium, aluminum, titanium, cobalt, and alloys thereof.

  The resin composition of the present invention is suitably used for the production of various articles, particularly for the production of optical recording media, because the cured product has little warpage and high hardness. In an optical recording medium, it can be used as a light transmission layer or a protective layer. Examples of the optical recording medium include a Blu-ray disc.

  The optical recording medium can have a structure having an information recording surface on a support substrate and a light transmission layer on the information recording surface. Further, recording light or reproducing light is incident through this light transmission layer, so that information can be recorded on the information recording surface or information on the information recording surface can be read out.

  Examples of the support base for the optical recording medium include metals, glass, ceramics, plastics, and composite materials thereof. In particular, thermoplastic resins such as methyl methacrylate resin, polyester, polylactic acid, polycarbonate, and amorphous polyolefin are preferable in that a conventional optical disk manufacturing process can be used.

  The material of the information recording surface of the optical recording medium is not particularly limited, and a material applicable to a read-only medium, a phase change recording medium, a pit formation type recording medium, a magneto-optical recording medium, or the like is used as necessary. be able to. For example, gold, silver, silver / Pd / Cu alloy, silver / In / Te / Sb alloy, silver / In / Te / Sb / Ge alloy, aluminum, Al / Ti alloy, Ge / Sb / Te alloy, Ge / Sn A single metal or an alloy such as an Sb / Te alloy, an Sb / Te alloy, or a Tb / Fe / Co alloy can be used. Various metal compounds can also be used. On the other hand, organic dyes such as azo compounds can also be used. When using an organic dye, it is preferable to provide a protective layer on the recording layer formed of the organic dye. Materials for the protective layer include silicon oxide, particularly silicon dioxide, oxides such as zinc oxide, cerium oxide, and yttrium oxide; sulfides such as zinc sulfide and yttrium sulfide; nitrides such as silicon nitride; silicon carbide; oxides A mixture of sulfur compounds with sulfur can be used.

A dielectric layer such as SiN, ZnS, and SiO ₂ can be provided on at least one side of the information recording surface for the purpose of optical effects such as protecting the information recording surface and changing the reflectance of the laser beam.

  The light transmission layer is a cured product of the above-mentioned active energy ray-curable resin composition, and the thickness is preferably 0.5 to 300 μm. The thickness of the light transmission layer is preferably 1 to 200 μm, and more preferably 1.5 to 150 μm. Moreover, it is preferable to have transparency to a laser beam having a wavelength of about 400 nm for recording and reproduction on the information recording surface. If bubbles exist in the light transmission layer, it may cause reading or writing errors. Therefore, the resin composition is preferably deaerated beforehand under vacuum, ultrasonic vibration, centrifugal rotation conditions, or a combination thereof.

  The active energy ray-curable resin composition can be cured by irradiation with active energy rays.

  Examples of active energy rays include α rays, β rays, γ rays, X rays, ultraviolet rays, and visible rays. Ultraviolet rays are particularly preferable from the viewpoint of workability and curability. Examples of the light source for irradiating ultraviolet rays include a high-pressure mercury lamp, a metal halide lamp, a xenon flash lamp, and an LED lamp. From the viewpoints of curability of the active energy ray-curable resin composition and wear resistance of the cured product, a high-pressure mercury lamp and a metal halide lamp are particularly preferable.

  From the viewpoint of workability, the active energy ray-curable resin composition is preferably applied onto a substrate by a known coating method such as a spin coating method, a spray coating method, or a brush coating method. The thickness of the resulting coating film is preferably 10 to 300 μm after curing. Moreover, it is more preferable to set it as the thickness of 50-150 micrometers. The substrate refers to a support substrate alone or a substrate on which an information recording surface of an inorganic material such as a metal or an organic material such as an organic dye is formed.

  The coating film obtained above is cured by active energy rays, and a light transmission layer made of an active energy ray-curable resin composition is formed on the information recording surface, whereby an optical recording medium is obtained.

  The atmosphere for irradiating the coating film with active energy rays may be either air or an inert gas such as nitrogen or argon, but air is preferred in terms of production cost.

  According to the present invention, an optical recording medium having a light transmission layer excellent in hardness and low warpage can be obtained.

  An active energy ray-curable resin composition was prepared, and an optical recording medium for evaluation was prepared using the composition. Evaluation items and evaluation methods are shown below.

(1) Low warpage The warp angle was measured in an environment of 23 ° C. and 50% relative humidity by using IOPC blue Tilt-scanner (trade name, manufactured by dr. Schwab Inspection Technology GmbH). The warp angle means a radial tilt at a position 48 mm from the center of the optical recording medium. The criteria for determining low warpage are as follows.
○: The absolute value of the warp angle is within 0.30 °.
X: The absolute value of the warp angle exceeds 0.30 °.

(2) Hardness Using a Fischerscope HM2000 (trade name, manufactured by Fischerscope), the Martens hardness of the cured product was measured according to ISO14577. The indenter used was a diamond pyramid with a face angle of 135 degrees. Specifically, the indenter is weighted to 50 mN in 10 seconds so that dF / dt ² (F = load, t = elapsed time) is constant with respect to the cured product, and then creeped for 5 seconds. Was deweighted. The criteria for determining hardness are as follows.
A: Martens hardness exceeds 100 N / mm ² .
◯: Martens hardness exceeds 50 N / mm ² and 100 N / mm ² or less.
X: Martens hardness is 50 N / mm ² or less.

(3) High-temperature and high-humidity resistance A sample for evaluation (optical recording medium for evaluation) was allowed to stand in an environment of 80 ° C. and 85% relative humidity for 100 hours, and then the silver alloy reflective film and the active energy ray-curable resin composition were used. The appearance of the cured product was visually confirmed. The criteria for high temperature and high humidity resistance are as follows.
○: No corrosion was observed on the silver alloy reflective film.
X: Corrosion was observed on the silver alloy reflective film.

(4) Mass average molecular weight It measured using gel permeation chromatography (GPC) "HLC-8120" (brand name. Tosoh Corporation make). As the column, TSKgel G5000HXL * GMHXL-L (trade name, manufactured by Tosoh Corporation) was used. In addition, a calibration curve was prepared by using F288 / F80 / F40 / F10 / F4 / F1 / A5000 / A1000 / A500 (trade name, manufactured by Tosoh Corporation) and styrene as standard polystyrene.

  Measurement was carried out at 40 ° C. using 100 μl of a solution in which a polymer (acrylic polymer) was dissolved in tetrahydrofuran to a concentration of 0.4% by mass. The mass average molecular weight was calculated in terms of standard polystyrene.

(5) Glass transition temperature High-sensitivity differential scanning calorimeter Thermoplus EVO II / DSC 8230 (trade name, manufactured by Rigaku Co., Ltd.) is used in a nitrogen gas atmosphere with α-alumina as a reference and in accordance with JIS-K-7121. About 10 mg of the sample was heated from room temperature to 120 ° C. at a heating rate of 20 ° C./min to obtain a DSC curve, a straight line obtained by extending the base line on the low temperature side of the DSC curve to the high temperature side, and the steps of the glass transition The temperature at the intersection (extrapolated glass transition start temperature) with the tangent drawn at the point where the curve gradient of the shaped portion becomes the maximum was taken as the glass transition temperature.

(6) Acrylic polymer structure A polymer (acrylic polymer) was dissolved in deuterated chloroform and identified with a nuclear magnetic resonance apparatus EXcalibur 270 superconducting FT-NMR (trade name, manufactured by JEOL Ltd.).

[Production Example 1] Production of Dispersant A In a flask equipped with a stirrer, a condenser tube and a thermometer, 900 parts by mass of deionized water, 60 parts by mass of sodium 2-sulfoethyl methacrylate, 10 parts by mass of potassium methacrylate and methacrylic acid. 12 parts by mass of methyl acid was added and stirred, and the temperature in the flask was raised to 50 ° C. while purging with nitrogen. Next, 0.08 parts by mass of 2,2′-azobis (2-methylpropionamidine) dihydrochloride as a polymerization initiator was added to the flask, and the temperature was further raised to 60 ° C. After the temperature rise, 18 parts by mass of methyl methacrylate was continuously added dropwise at a rate of 0.24 parts by mass / min using a dropping pump. The obtained reaction solution was kept at 60 ° C. for 6 hours and then cooled to room temperature to obtain a transparent aqueous solution having a solid content of 10% by mass (referred to as Dispersant A).

[Production Example 2] Production of chain transfer agent A In a flask equipped with a stirrer, 1.00 g of cobalt (II) acetate tetrahydrate, 1.93 g of diphenylglyoxime and nitrogen bubbling were previously carried out under a nitrogen atmosphere. 80 ml of oxygenated diethyl ether was added and stirred at room temperature for 30 minutes. Next, 10 ml of boron trifluoride diethyl ether complex was added, and the mixture was further stirred for 6 hours. The obtained reaction product was filtered, the solid content was washed with diethyl ether, and vacuum dried for 15 hours to obtain 2.12 g of a chain transfer agent (referred to as chain transfer agent A) as a reddish brown solid.

[Production Example 3] Production of acrylic polymer (AP-A) In a flask equipped with a stirrer, a condenser tube and a thermometer, 145 parts by mass of deionized water, 0.1 part by mass of sodium sulfate and 0.25 part by mass of dispersant A A portion was added and stirred to obtain a uniform aqueous solution. Next, 100 parts by weight of methyl methacrylate, 0.005 parts by weight of chain transfer agent A and 0.5 parts by weight of 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate as acrylic monomers were added to the flask. The monomer mixture was added to give an aqueous suspension. Thereafter, the inside of the flask was purged with nitrogen, heated to 80 ° C. and reacted for 1 hour, and further heated to 93 ° C. and held for 1 hour in order to increase the polymerization rate. Thereafter, the reaction solution was cooled to 40 ° C. to obtain an aqueous polymer suspension. This aqueous polymer suspension is filtered through a nylon filter cloth having an opening of 45 μm, and the residue is washed with deionized water, dehydrated, dried at 40 ° C. for 16 hours, and then an acrylic polymer (hereinafter referred to as AP-A). ) AP-A had a mass average molecular weight of 6000 and a glass transition temperature of 82 ° C. In addition, AP-A had a structure in which R is a methyl group in formula (1).

[Production Example 4] Production of acrylic polymer (AP-B) An acrylic polymer (hereinafter referred to as AP-B) was obtained in the same manner as in Production Example 3 except that the amount of chain transfer agent A was changed to 0.01 parts by mass. It was. AP-B had a weight average molecular weight of 3600 and a glass transition temperature of 58 ° C. AP-B had a structure in which R in the formula (1) was a methyl group.

[Production Example 5] Production of acrylic polymer (AP-C) 100 parts by mass of methyl methacrylate to 60 parts by mass of methyl methacrylate and 40 parts by mass of isobornyl methacrylate, the amount of chain transfer agent A to 0.008 parts by mass, An acrylic polymer (hereinafter referred to as AP-C) was prepared in the same manner as in Production Example 3 except that the amount of 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate was changed to 0.9 parts by mass. Obtained. AP-C had a weight average molecular weight of 4700 and a glass transition temperature of 79 ° C. AP-C had a structure in which R is a methyl group in formula (1).

[Production Example 6] Production of Urethane Acrylate (UA) Isophorone diisocyanate (Desmodur I manufactured by Sumitomo Bayer Urethane Co., Ltd. (commodity) was added to a 5-liter three-necked flask equipped with a stirrer, temperature controller, thermometer and condenser. Name): Hydrolyzed chlorine amount 60 ppm) 1112 g (10 molar equivalents) and dibutyltin dilaurate 0.5 g were charged and heated in a water bath so that the internal temperature became 70 ° C.

  Then, 193 g (2.4 molar equivalent) of N-methyl-N- (2-hydroxyethyl) -3-hydroxypropylamide and 1105 g (2.6 molar equivalent) of polybutylene glycol (n = 12; number average molecular weight: 850) ) Is uniformly mixed and dissolved in a dropping funnel with a side tube, and the liquid in the dropping funnel is stirred while the contents in the flask are being stirred while the flask internal temperature is kept at 65 to 75 ° C. The solution was added dropwise at a constant time drop, and the reaction was allowed to stir at the same temperature for 2 hours. Next, after the temperature of the flask contents was lowered to 60 ° C., a solution obtained by uniformly mixing and dissolving 581 g (5 molar equivalents) of 2-hydroxyethyl acrylate and 1.5 g of hydroquinone monomethyl ether charged in another dropping funnel was added to the flask. After dropping by constant speed dropping for 2 hours while keeping the internal temperature at 55 to 65 ° C., the temperature of the flask contents is kept at 75 to 85 ° C. for 4 hours to react to form a bifunctional urethane acrylate (hereinafter referred to as UA). Manufactured.

[Example 1]
Each raw material was mix | blended with the mixture ratio (mass part) shown in Table 1, and the active energy ray hardening-type resin composition was prepared.

A film of Ag ₉₈ Pd ₁ Cu ₁ (atomic ratio) alloy is formed on one side of a polycarbonate resin optical disk support base (diameter: 12 cm, plate thickness: 1.1 mm, warp angle: 0 degree) by a sputtering method so as to have a film thickness of 20 nm. Thus, an optical disk substrate for evaluation having a silver alloy reflective film on the mirror surface (a warp angle of 0 degree) was obtained. On the obtained silver alloy reflective film, the active energy ray-curable resin composition was applied using a spin coater in an atmosphere of an ambient temperature of 23 ° C. and a relative humidity of 50%. Furthermore, from the upper side of the coated surface, ultraviolet rays were irradiated with an energy amount of 1500 mJ / cm ² (UV light meter, UV-351SN type, measured by Oak Manufacturing Co., Ltd.) using a high-pressure mercury lamp. Was cured to obtain an evaluation sample (evaluation optical recording medium) having a cured product layer having an average film thickness of 100 μm. The evaluation results are shown in Table 1.

[Examples 2 to 11 and Comparative Example 1]
In each example, an active energy ray-curable resin composition was prepared in the same manner as in Example 1 except that each raw material was blended in the blending ratio (parts by mass) shown in Table 1, and a sample for evaluation was prepared. The evaluation results are shown in Table 1.

The abbreviations in Table 1 indicate the following compounds.
・ (A) component (acrylic polymer)
AP-A: acrylic polymer obtained in Production Example 3.
AP-B: acrylic polymer obtained in Production Example 4.
AP-C: acrylic polymer obtained in Production Example 5.
-(B-1) component (radically polymerizable compound)
FA324A: di (meth) acryloyl polyethoxylated bisphenol A, {trade name: funcryl FA-324A, manufactured by Hitachi Chemical Co., Ltd.}.
FAP324A: Di (meth) acryloyl polypropoxylated bisphenol A, {trade name: FANCLIL FAP-324A, manufactured by Hitachi Chemical Co., Ltd.}.
TMP3P: trimethylolpropane triacrylate modified with 3 propylene oxides per molecule, {trade name: New Frontier TMP-3P, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.}
FA220: Polyethylene glycol diacrylate, {trade name: FANCLIL FA-220, manufactured by Hitachi Chemical Co., Ltd.}.
TCDDA: tricyclodecane dimethanol diacrylate, {trade name: Light acrylate DCP-A, Kyoeisha Chemical Co., Ltd.}.
R604: Neopentyl glycol-modified trimethylolpropane diacrylate, {trade name: Kayarad R-604, manufactured by Nippon Kayaku Co., Ltd.}.
TMP6E: trimethylolpropane triacrylate modified with 6 ethylene oxides per molecule, {trade name: Aronix M-360, manufactured by Toagosei Co., Ltd.}
UA: bifunctional urethane acrylate obtained in Production Example 6.
-(B-2) Component THFA: Tetrahydrofurfuryl acrylate {Brand name: Biscote # 150, manufactured by Osaka Organic Chemical Industry Co., Ltd.}.
PEA: Phenoxyethyl acrylate {trade name: New Frontier PHE, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.}.
MEDA: 2-ethyl-2-methyl-1,3-dioxolan-4-yl-methyl (meth) acrylate {trade name: MEDOL-10, manufactured by Osaka Organic Chemical Industry Co., Ltd.}.
(C) Component HCPK: 1-hydroxycyclohexyl-phenyl ketone.
-Other APMA: 2-methacryloyloxyethyl acid phosphate {trade name: Kayamar PM-2, manufactured by Nippon Kayaku Co., Ltd.}. Note that APMA is an adhesion promoter for metal.

  In Examples 1 to 11, low warpage and hardness were good, but in Comparative Example 1 in which the component (A) was replaced with urethane acrylate, low warpage was good but hardness was poor. .

Claims (9)

100 mass parts of a polymer component containing 5 to 50 mass% of an acrylic polymer (A) having a mass average molecular weight of 3000 to 30000 and 50 to 95 mass% of a radical polymerizable compound (B), and a photopolymerization initiator (C) 1 to 20 An active energy ray-curable resin composition containing parts by mass,
The radically polymerizable compound (B) is an active energy ray-curable resin composition containing a component (b-1) that is a compound having two or more (meth) acryloyl groups in one molecule. The active energy ray-curable resin composition according to claim 1, wherein the acrylic polymer (A) is an acrylic polymer having a structure represented by the formula (1).


In the formula (1), R represents any one of a substituted or unsubstituted alkyl group, cycloalkyl group, and aryl group. Moreover, a substituent shows either an epoxy group, a hydroxy group, a cyano group, an amino group, and a carboxyl group.   The active energy ray-curable resin composition according to claim 1 or 2, comprising a compound having 2 or 3 (meth) acryloyl groups in one molecule as the component (b-1).   The active energy ray according to any one of claims 1 to 3, further comprising (b-2) component which is a compound having one (meth) acryloyl group in one molecule as the radical polymerizable compound (B) component. A curable resin composition.   The active energy ray-curable resin composition according to claim 1, wherein the content of the organic solvent is 1% by mass or less.   The glass transition temperature of acrylic polymer (A) is 50 degreeC or more, The active energy ray hardening-type resin composition in any one of Claims 1-5.   (B-1) As a component, biphenol A di (meth) acrylate modified with 4 to 6 alkylene oxides per molecule, tricyclodecane dimethanol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di ( The active energy ray-curable resin composition according to any one of claims 1 to 6, comprising any one of (meth) acrylate and trimethylolpropane tri (meth) acrylate modified with 3 to 6 alkylene oxides per molecule. .   An article having a layer made of a cured product of the active energy ray-curable resin composition according to any one of claims 1 to 7 on a metal.   An optical recording medium having a layer made of a cured product of the active energy ray-curable resin composition according to claim 1.