JP2009256503A - Curable composition, and optical information medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable composition which is excellent in the curability and is excellent in the protective performance for a reflecting film of or a recording film of an optical information medium and is excellent in light resistance of no yellowing of the light transmissible layer with time. <P>SOLUTION: The curable composition, containing a urethane (meth)acrylate (A), particular (meth)acrylates (B) and (C), and a photopolymerization initiator (D), is characterized in that the curable composition is a urethane (meth)acrylate(A) which is synthesized from an isocyanate compound (a1), at least one kind of polyhydric alcohol (a2) selected from polyether polyols, polyester polyols and polylactone polyols, and a hydroxyl group-containing (meth)acrylate (a3). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a curable composition suitable for a light transmission layer of an optical information medium such as a read-only optical disk and a recording optical disk, and has excellent curability and has a protective property for a reflective film or a recording film of the optical information medium. The present invention relates to a curable composition that is excellent and has excellent light resistance such that a light-transmitting layer does not turn yellow over time.

  In recent years, various researches on density increase have been made in the field of information recording media. Also in the field of optical discs, DVDs having a structure in which a substrate with a thickness of 0.6 mm capable of recording a moving image is bonded are becoming popular.

  However, as digital high-definition broadcasting spreads in the future, it is expected that an optical disk with a larger capacity will be required. Therefore, the light transmission layer on the information recording surface of the support base having the information recording surface formed on the surface is 0.1 mm thick, the lens numerical aperture NA is about 0.85, and the wavelength of the recording and reproducing laser light is 400 nm. A high-density optical disk system with a certain degree has been proposed and put into practical use.

  As a method for forming the light-transmitting layer having a thickness of 0.1 mm, a method of forming a light-transmitting layer by applying a liquid ultraviolet curable resin by spin coating and curing it by irradiation with active energy rays has been developed. (For example, Patent Document 1).

  Moreover, the curable composition which is excellent in mechanical physical property and can be used for the 0.1 mm-thick light transmission layer of a high-density optical disk is developed (for example, patent documents 2-4).

However, when the composition described in Patent Documents 2 to 4 is used for the light transmission layer, the curability at the time of ultraviolet curing is poor, and the warping of the high-density optical disk becomes large due to the curing shrinkage at the time of ultraviolet curing, There was a problem that the cured product yellowed with time.
JP 2003-85836 A JP-A-7-62267 JP-A-6-145276 JP-A-3-265669

  The present invention has been made to solve the above-described problems, and is excellent in curability, tensile properties of a cured product, and protection performance of a reflective film or a recording film of an optical information medium, and the light transmission layer is yellowed over time. An object of the present invention is to provide an optical information medium having a light transmission layer excellent in light resistance.

The present invention is at least one of urethane (meth) acrylate (A), (meth) acrylate (B) represented by the following formula (1), and (meth) acrylate represented by the following formulas (2) and (3). A curable composition containing (C) and a photopolymerization initiator (D), wherein the urethane (meth) acrylate (A) is selected from an isocyanate compound (a1), a polyether polyol, a polyester polyol, and a polylactone polyol. The curable composition is a urethane (meth) acrylate synthesized from at least one polyhydric alcohol (a2) and a hydroxyl group-containing (meth) acrylate (a3).

(R ¹ represents hydrogen or a methyl group, R ² represents a divalent hydrocarbon group having 1 to 4 carbon atoms, and m represents an integer of 0 to 10)

(R ³ represents hydrogen or a methyl group, R ⁴ represents a divalent hydrocarbon group having 1 to ⁴ carbon atoms, and n represents an integer of 0 to 10.

(R ⁵ is hydrogen or a methyl group, R ⁶ is a divalent hydrocarbon group having 1 to 4 carbon atoms, R ⁷ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and p is an integer of 0 to 10) Indicates.

  Further, the present invention has a light transmission layer on the information recording surface of a support base having an information recording surface formed on the surface, and is used so that at least one of recording light and reproduction light enters through the light transmission layer. An optical information medium, wherein the light transmission layer is a cured product of the curable composition described above.

  The curable composition of the present invention is excellent in curability, tensile properties of the cured product, protection performance of the reflection film or recording film of the optical information medium, and light resistance excellent in that the light transmission layer does not yellow over time. It is suitable for an optical information medium having a transmission layer.

  The curable composition of the present invention comprises a urethane (meth) acrylate (A) (hereinafter referred to as “component A”), a (meth) acrylate (B) represented by formula (1) (hereinafter referred to as “component B”). ), At least one of (meth) acrylates represented by formulas (2) and (3) (hereinafter referred to as “component C”) and photopolymerization initiator (D) (hereinafter referred to as “component D”). Containing.

  Component A constituting the curable composition of the present invention contains at least one polyhydric alcohol selected from an isocyanate compound (a1) (hereinafter referred to as “component a1”), a polyether polyol, a polyester polyol, and a polylactone polyol ( a2) (hereinafter referred to as “component a2”) and a hydroxyl group-containing (meth) acrylate (a3) (hereinafter referred to as “component a3”).

  Component A is a component that imparts low shrinkage to the curable composition, and is a component that imparts toughness and flexibility to the cured product, and is synthesized from component a1, component a2, and component a3. The

  Examples of the component a1 include hexamethylene diisocyanate, isophorone diisocyanate, bis (4-isocyanatocyclohexyl) methane, bis (4-isocyanatophenyl) methane, bis (3-chloro-4-isocyanatophenyl) methane, 4-tolylene diisocyanate, 2,6-tolylene diisocyanate, tris (4-isocyanatophenyl) methane, 1,2-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,2-hydrogenated xylylene diisocyanate, 1,4-hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate, hydrogenated tetramethyl xylylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, norbornane diisocyanate, etc. Cyanates and the like. These can be used alone or in combination of two or more.

  Among them, since it can impart excellent toughness and hard yellowing to the cured product, isophorone diisocyanate, bis (4-isocyanatocyclohexyl) methane, 1,2-hydrogenated xylylene diisocyanate, 1,4-hydrogenated xylylene diisocyanate Diisocyanate compounds having an alicyclic skeleton such as hydrogenated tetramethylxylylene diisocyanate and norbornane diisocyanate are preferred.

  As the component a2, for example, various commercially available polyhydric alcohols can be used. Specific examples thereof include polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and 1-methylbutylene glycol; neopentyl glycol, ethylene glycol, diethylene glycol, propylene glycol, 1,6-hexanediol, 1, 4-butanediol, 1,9-nonanediol, 1,10-decanediol, 3-methylpentanediol, 2,4-diethylpentanediol, tricyclodecane dimethanol, 1,4-cyclohexanedimethanol, 1,2 -Multivalent alcohols such as cyclohexanedimethanol, 1,3-cyclohexanedimethanol, cyclohexanediol, hydrogenated bisphenol A, bisphenol A, trimethylolpropane, pentaerythritol Polyesters obtained by reacting alcohols with polybasic acids such as succinic acid, phthalic acid, hexahydrophthalic acid, terephthalic acid, adipic acid, azelaic acid, tetrahydrophthalic acid, or acid anhydrides of these polybasic acids Examples of polyols include polycaprolactone polyols obtained by reacting these polyhydric alcohols with lactones such as ε-caprolactone, γ-butyrolactone, γ-valerolactone, and δ-valerolactone. These can be used alone or in combination of two or more.

  Among these, polytetramethylene glycol and polycaprolactone polyols have good curability of the composition and excellent strength-elongation balance of the obtained cured product. Therefore, the cured product is used as a light transmission layer of an optical information medium. Excellent dimensional stability of optical information media when used. In addition to the component a2, for example, a cyclic hydroxycarboxylic acid ester and ammonia, or a compound containing one primary or secondary amino nitrogen, for the purpose of improving the strength-elongation balance of the obtained light transmission layer Amide polyols obtained by the reaction, specifically, N-methyl-N- (2-hydroxyethyl) -4-hydroxybutanamide and the like may be used.

  Specifically, the component a3 may be a hydroxy group-containing (meth) acrylic acid ester having at least one (meth) acryloyloxy group in the molecule and at least one hydroxy group in the molecule, There is no particular limitation. Specific examples thereof include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and cyclohexanedimethanol mono (meth) acrylate. , (Meth) acrylates such as trimethylolpropane di (meth) acrylate and pentaerythritol tri (meth) acrylate, and adducts of these caprolactones. These can be used alone or in combination of two or more. Of these, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate are particularly preferable because of low viscosity.

  The synthesis method of component A is not particularly limited, and a conventionally known urethane (meth) acrylate synthesis method can be used. Specifically, for example, 2 mol of diisocyanate is charged in a flask, and a known catalyst such as dibutyltin dilaurate is mixed in an amount of 50 to 300 ppm based on the total charge, and the temperature in the flask is adjusted to 40 to 60 ° C. While maintaining, 1 mol of a diol compound is dropped over 2 to 4 hours using a dropping funnel to obtain a urethane prepolymer. Thereafter, an equivalent hydroxyl group-containing (meth) acrylic acid ester is dropped onto the isocyanate group remaining at the end of the obtained urethane prepolymer, and an addition reaction may be performed at a flask internal temperature of 60 to 75 ° C.

  In the present invention, the proportion of component A used is ethylene other than components A to C described below, based on a total of 100% by mass of component A, component B and component C from the viewpoint of low shrinkage of the curable composition. When the unsaturated unsaturated compound (E) (hereinafter also referred to as “component E”) is contained, the content is preferably 20% by mass or more based on the total of 100% by mass of component A, component B, component C and component E, and curable composition In order to reduce the viscosity of the product to improve the coating workability, the content is preferably 80% by mass or less. Further, the lower limit is particularly preferably 30% by mass or more, and the upper limit is particularly preferably 70% by mass or less.

  When the lower limit of the content of component A is 20% by mass or more, the effect of reducing the curing shrinkage of the composition is sufficiently exhibited, and the flexibility of the obtained cured product tends to be good. Moreover, when the upper limit is 80 mass% or less, the liquid viscosity of the composition obtained will become low, and it exists in the tendency for the coating workability | operativity to a base material to become favorable.

  The (meth) acrylate (B) represented by the formula (1) constituting the curable composition of the present invention adjusts the viscosity of the curable composition, and the light-transmitting layer does not turn yellow as time passes. It is a component for imparting light resistance.

  Examples of component B include dicyclopentenyl (meth) acrylate, dicyclopentenyloxymethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyloxypropyl (meth) acrylate, and dicyclopentenyloxydiethylene glycol. (Meth) acrylate, dicyclopentenyloxytriethylene glycol (meth) acrylate, dicyclopentenyloxypolyethylene glycol (meth) acrylate, dicyclopentenyloxydipropylene glycol (meth) acrylate, dicyclopentenyloxytripropylene glycol (meth) Examples include acrylate and dicyclopentenyloxypolypropylene glycol (meth) acrylate. These can be used alone or in combination of two or more. Of these, dicyclopentenyl (meth) acrylate and dicyclopentenyloxyethyl (meth) acrylate are preferable because of low viscosity.

  In the present invention, the proportion of component B used is based on the total of 100% by mass of component A, component B and component C, or from component A, component B and component, from the viewpoint of low viscosity and light resistance of the curable composition. 5 mass% or more is preferable on the basis of the total of 100 mass% of C and the component E, and 30 mass% or less is preferable from a viewpoint of the strong elongation balance of a curable composition. Further, the lower limit is particularly preferably 10% by mass or more, and the upper limit is particularly preferably 25% by mass or less.

  When the lower limit of the content of Component B is 5% by mass or more, the effect of the light resistance of the cured product is sufficiently exhibited, and the resulting curable composition tends to have a low viscosity. Moreover, when the upper limit is 30% by mass or less, the strength and elongation balance of the resulting composition tends to be good.

  Component C is a component for reducing the viscosity of the curable composition and improving the curability of the curable composition.

  In the present invention, at least one of the compound represented by formula (2) and the compound represented by formula (3) is used. Specific examples of the compound represented by the general formula include tetrahydrofurfuryl (meth) acrylate, tetrahydrofurfuryloxymethyl (meth) acrylate, and tetrahydrofurfuryloxyethyl as the compound represented by the formula (2). (Meth) acrylate, tetrahydrofurfuryloxypropyl (meth) acrylate, tetrahydrofurfuryloxydiethylene glycol (meth) acrylate, tetrahydrofurfuryloxytriethylene glycol (meth) acrylate, tetrahydrofurfuryloxypolyethylene glycol (meth) acrylate, tetrahydrofur Furyloxydipropylene glycol (meth) acrylate, tetrahydrofurfuryloxytripropylene glycol (meth) acrylate, tetrahydride Furfuryl oxy polypropylene glycol (meth) acrylate and the like.

  Moreover, as a compound represented by Formula (3), 2-ethyl-2-methyl-1,3-dioxolan-4-yl-methyl (meth) acrylate, 2-isobutyl-2-methyl-1,3-dioxolane -4-yl-methyl (meth) acrylate and the like.

  These can be used alone or in combination of two or more. Among these, tetrahydrofurfuryl (meth) acrylate and 2-ethyl-2-methyl-1,3-dioxolan-4-yl-methyl (meth) acrylate are preferable because of low viscosity.

  In the present invention, the proportion of component C used is based on the total of 100% by mass of component A, component B and component C from the viewpoint of low viscosity and curability of the curable composition, or component A, component B, component 10 mass% or more is preferable on the basis of the total of 100 mass% of C and the component E, and 40 mass% or less is preferable from a viewpoint of the strong elongation balance of a curable composition. Further, the lower limit is particularly preferably 12% by mass or more, and the upper limit is particularly preferably 30% by mass or less.

  When the lower limit of the content of Component C is 10% by mass or more, the present curable composition tends to have low viscosity and good curability. Moreover, when the upper limit is 40 mass% or less, the strength-elongation balance of the resulting composition tends to be good.

  Component D is a component for efficiently curing the curable composition by irradiation with active energy.

  Examples of component D include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 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-hydroxycyclohexylphenyl Ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzi 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, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} Examples include 2-methylpropan-1-one and methylbenzoyl formate.

  Among these, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl phenyl ketone are preferable in terms of curability of the curable composition and non-yellowing property of the cured product. .

  Component D can be used alone or in combination of two or more.

  In the present invention, the proportion of component D used is 100 parts by mass of component A, component B and component C, or component A, component B, component C and component from the viewpoint of curability of the curable composition. 0.1 mass part or more is preferable with respect to 100 mass parts in total of E, and 10 mass parts or less are preferable from a viewpoint of the strong elongation balance of a curable composition. Further, the lower limit is particularly preferably 1 part by mass or more, and the upper limit is particularly preferably 8 parts by mass or less.

  When the lower limit of the content of Component D is 0.1 parts by mass or more, the curability of the present curable composition tends to be good. Moreover, when the upper limit is 10 mass parts or less, it exists in the tendency for the deep part curability of this curable composition, the hard yellowing of this hardened | cured material, and the film thickness stability of a light transmissive layer to become favorable.

  The curable composition used in the present invention is composed of the aforementioned component A, component B, component C, and component D as constituents, but as long as it does not impair the characteristics of the present invention. The ethylenically unsaturated compound (E) other than these components A to C can be contained.

  Examples of the component E include trifunctional or higher polyfunctional (meth) acrylates, di (meth) acrylates, mono (meth) acrylates, and polyester poly (meth) acrylates.

  Specific examples of trifunctional or higher polyfunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trisethoxylated trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tris. (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 Rate and caprolactone-modified dipentaerythritol hexa (meth) acrylate.

  Specific examples of di (meth) acrylate include hydroxypivalate neopentyl glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polybutylene glycol di (meth) acrylate, Tricyclodecane dimethanol di (meth) acrylate, bis (2-acryloyloxyethyl) -2-hydroxyethyl isocyanurate, cyclohexanedimethanol di (meth) acrylate, polyethoxylated cyclohexanedimethanol di (meth) acrylate, poly Propoxylated cyclohexanedimethanol di (meth) acrylate, di (meth) acryloyloxypolyethoxylated bisphenol A, di (meth) acryloyloxy Polypropoxylated bisphenol A, di (meth) acryloyloxy hydrogenated bisphenol A, di (meth) acryloyloxy polyethoxylated hydrogenated bisphenol A, di (meth) acryloyloxy polypropoxylated hydrogenated bisphenol A, bisphenoxy Fluorene ethanol di (meth) acrylate, neopentyl glycol-modified trimethylolpropane di (meth) acrylate, ethylene oxide-modified phosphate di (meth) acrylate, caprolactone-modified phosphate di (meth) acrylate, hydroxypivalate neopentyl glycol ε -Di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate of caprolactone adduct (addition number; n + m = 2 to 5) 1,4-butanediol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate 2,4-diethyl-1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,7-heptanediol di (meth) acrylate, 1,8-octanediol di (Meth) acrylate, 1,9-nonanediol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,11-undecane Diol di (meth) acrylate, 1,12-dodecanediol di (meth) acryl Over DOO, 1,13-tri-decanediol di (meth) acrylate and 1,14-tetradecanediol di (meth) acrylate.

  Specific examples of mono (meth) acrylate include 2-ethyl-hexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, isobornyl ( (Meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, caprolactone modified phosphorus Acid (meth) acrylate, trimethylolpropane formal (meth) acrylate, 2-ethyl-hexyloxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 3-metho Sibutyl (meth) acrylate, phenyloxyethyl (meth) acrylate, phenyloxydiethylene glycol (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, nonylphenyloxyethyl (meth) acrylate, paracumylphenyloxyethyl (meth) acrylate, Dicyclopentanyloxyethyl (meth) acrylate, cyclohexyloxyethyl (meth) acrylate, t-butylcyclohexyloxyethyl (meth) acrylate, benzyloxyethyl (meth) acrylate, isobornyloxyethyl (meth) acrylate, norvol Nyloxyethyl (meth) acrylate, adamantyloxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate , Methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene glycol (meth) acrylate, methoxydibutylene glycol (meth) acrylate, methoxytributylene glycol (meth) acrylate, ethoxydiethylene glycol ( (Meth) acrylate, ethoxytriethylene glycol (meth) acrylate, ethoxydipropylene glycol (meth) acrylate, ethoxytripropylene glycol (meth) acrylate, ethoxydibutylene glycol (meth) acrylate, ethoxytributylene glycol (meth) acrylate and butoxy Examples include ethyl (meth) acrylate. Specific examples of the polyester poly (meth) acrylate include polybasic acids such as phthalic acid, succinic acid, hexahydrophthalic acid, tetrahydrophthalic acid, terephthalic acid, azelaic acid, and adipic acid, ethylene glycol, hexanediol, polyethylene glycol, The compound obtained by reaction with polyhydric alcohols, such as polytetramethylene glycol, and (meth) acrylic acid or its derivative (s) is mentioned.

  Among the above components E, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) are used in terms of improving the mechanical properties of the cured product. Acrylate, tris (2-acryloyloxyethyl) isocyanurate, dipentaerythritol hexa (meth) acrylate, tetraethylene glycol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, ethylene oxide modified di (meth) phosphate ) Acrylate, caprolactone-modified di (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (me ) Acrylate, 1,9-nonanediol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 4-hydroxybutyl (meth) Acrylate, 2-ethyl-2-methyl-1,3-dioxolan-4-yl-methyl (meth) acrylate, isobornyl (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, caprolactone modified phosphoric acid (meth) acrylate , And at least one selected from isophorone diisocyanate as the isocyanate component, polycaprolactone diols and amide diols as the polyhydric alcohol component, and 2-hydroxyethyl (meth) acrylate as the hydroxyl group-containing (meth) acrylate component Urethane is synthesized from 3-component (meth) acrylate and the like even without.

  In the present invention, the proportion of component E used is preferably 5% by mass or more based on the total of 100% by mass of component A, component B, component C and component E from the viewpoint of low viscosity and curability of the curable composition. From the viewpoint of the high elongation balance of the curable composition, 30% by mass or less is preferable. Further, the lower limit is particularly preferably 8% by mass or more, and the upper limit is particularly preferably 20% by mass or less.

  When the lower limit of the content of Component E is 5% by mass or more, the curability of the present curable composition tends to be good. Moreover, when the upper limit is 30% by mass or less, the strength and elongation balance of the resulting composition tends to be good.

  In the present invention, the curable composition contains the aforementioned component A, component B, component C, and component D.

  In the present invention, as long as the characteristics of the present invention are not impaired, the present curable composition includes, for example, a thermal polymerization initiator, an antioxidant, a light stabilizer, a photosensitizer, a thermoplastic resin, and a slip agent. In addition, known additives such as a leveling agent, an ultraviolet absorber, a polymerization inhibitor, a silane coupling agent, an inorganic filler, an organic filler, and an inorganic filler subjected to surface organic treatment can be appropriately blended.

  The blending amount in the case of blending the antioxidant and the light stabilizer is not particularly limited, but 0.001 to 5 parts by mass is preferable with respect to 100 parts by mass in total of Component A, Component B and Component C, 0.01-3 mass parts is more preferable.

  The curable composition is preferably filtered using a filtration filter capable of removing foreign matters of 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.

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

  In the present invention, even if bubbles exist in the light transmission layer, it may cause reading or writing errors. Therefore, the present curable composition is previously subjected to vacuum, ultrasonic vibration, centrifugal rotation conditions, or a combination thereof. It is preferable to perform deaeration.

  The present curable 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.

  In the present invention, the curable composition is applied on the information recording surface formed on the support substrate by a known coating method such as spin coating, spray coating, or brush coating. A coating film of the present curable composition is formed on the recording surface. The thickness of the coating film is preferably 0.5 to 300 μm after curing.

  The coating film obtained above is cured by active energy rays, and a light transmission layer made of the cured product 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.

  In the present invention, the thickness of the light transmission layer tends to sufficiently protect the surface of the optical information medium when the thickness is 0.5 μm or more, and the warp of the optical information medium tends to be easily suppressed when the thickness is 300 μm or less.

  In the present invention, the curable composition is preferably cured so as to have a reaction rate of 90% or more in order to reduce the change in the thickness of the light transmission layer even under high temperature and high humidity conditions. When the reaction rate is 90% or more, it is possible to suppress the unreacted di (meth) acrylates and photopolymerization initiator remaining in the light transmission layer from volatilizing with time, and to reduce the decrease in film thickness. It tends to be possible. The reaction rate of the present curable composition is more preferably 93% or more, and still more preferably 95% or more.

  The elongation at break and tensile modulus at 23 ° C. of the cured product used in the present invention are preferably 20% or more and 80% or less, preferably 200 MPa or more and 1500 MPa or less, more preferably 25% or more and 70% or less, 500 MPa or more and 1200 MPa or less.

When the elongation at break is 20% or more, the warp of the obtained optical information medium tends to be small, and when it is 80% or less, the light transmission layer of the obtained optical information medium tends to be hardly damaged.
When the tensile elastic modulus is 200 MPa or more, the light transmission layer of the obtained optical information medium tends to be hardly damaged, and when it is 1500 MPa or less, the dimensional stability is excellent against external environmental changes (temperature and humidity). There is a tendency.
In order to set the elongation at break and the tensile modulus at 23 ° C. to 20% or more and 80% or less and 200 MPa or more and 1500 MPa or less, respectively, preferably, the cumulative amount of ultraviolet light is 500 mJ / cm ² or more, more preferably 1000 mJ / cm ^2. As described above, the curable composition is cured by irradiation under the condition of 2000 mJ / cm ² or more.

  As a method for measuring the reaction rate of the present curable composition, for example, a method of measuring the residual amount of (meth) acryloyl groups by infrared spectroscopy, the elastic modulus of the cured product, and the saturation of physical properties such as Tg Examples thereof include a method of measuring and a method of measuring the degree of crosslinking by gel fraction.

  Among the above methods, a method of measuring the gel fraction is preferable in that it is easy to quantify residues that cause a decrease in film thickness remaining in the cured product. Examples of the method for measuring the gel fraction include a method in which the main cured product is pulverized, an uncured component is extracted with a solvent and then dried, and the gel fraction is measured by a change in its weight.

Optical Information Medium The optical information medium of the present invention has a structure having an information recording surface on a support substrate and a light transmission layer on the information recording surface. The optical information medium is capable of recording information on the information recording surface and reading information on the information recording surface when recording light or reproducing light enters through the light transmission layer.

Support Substrate Examples of the support substrate used in the present invention include metal, glass, ceramics, paper, wood, plastic, 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.

Information recording surface The material of the information recording surface used in the present invention 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, etc. is required. Can be used according 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 Sb · Te alloys, Sb · Te alloys, Tb · Fe · Co alloys and dyes can be used.

In the present invention, a dielectric layer such as SiN, ZnS, or SiO ₂ is 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. be able to.

Light transmissive layer The light transmissive layer used in the present invention is a cured product of the curable composition described above, 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 of about 400 nm for recording and reproduction on the information recording surface.

Hereinafter, the present invention will be described in detail with reference to examples. In the following, “part” means “part by mass”.
In addition, the evaluation item in an Example and its evaluation method are shown below.

(1) Viscosity (Unit: mPa · s)
The viscosity of the curable composition was measured at 25 ° C. with an E-type viscometer “TVE-20” (trade name, manufactured by Toki Sangyo Co., Ltd.).

(2) Curability One side of a transparent disc-like mirror substrate (diameter 12 cm, plate thickness 1.1 mm, warp angle 0 degree) having an optical disk shape obtained by injection molding polycarbonate resin (saturated water absorption: 0.15%) Then, an Ag ₉₈ Pd ₁ Cu ₁ (atomic ratio) alloy was formed by sputtering so as to have a film thickness of 20 nm, and an optical disk substrate for evaluation having a silver alloy reflective film on the mirror surface was obtained. The obtained curable composition was coated on the silver alloy reflective film of the obtained substrate using a spin coater in an environment having an ambient temperature of 23 ° C. and a relative humidity of 50%. From the upper side of the coated surface, ultraviolet rays are irradiated with an energy amount of 200 mJ / cm ² (measured with UV-350 manufactured by Oak Co., Ltd.) using a D bulb lamp manufactured by Fusion UV Systems Japan Co., Ltd. The coating film was cured to obtain an evaluation optical disc having a cured product layer having an average film thickness of approximately 100 μm. The stickiness of the coated surface and the end surface of the optical disk was determined by greasy touch on the obtained cured product.
○ There is no stickiness on the coated surface and the end surface △ There is no stickiness on the coated surface, but the end surface is sticky × Both the coated surface and the end surface are sticky

(3) Elongation at break, tensile elastic modulus Except that a 10 mm × 100 mm × 100 μm test piece is cut out from the cured product layer peeled off from the evaluation optical disc, the distance between the marked lines is 50 mm, and the tensile speed is 20 mm / min. In accordance with JIS K7127-1999, the elongation at break (unit:%) and tensile elastic modulus (unit: MPa) were measured in an environment of 23 ° C. and 50% relative humidity.
<Elongation at break>
○ 20% or more × less than 20% <Tensile modulus>
○ 500MPa or more × less than 500MPa

(3) Protection performance An optical disc for evaluation having a cured product layer having an average film thickness of 100 μm was obtained in the same manner as described above except that the integrated light amount was set to an energy amount of 1000 mJ / cm ² . The obtained optical disk was left at 80 ° C. and 85% RH for 200 hours. After removal, the state of the Ag ₉₈ Pd ₁ Cu ₁ (atomic ratio) alloy, which is a reflective film, was observed.
○ There is no change in the reflective film as it was after the optical disc was created. X The reflective film is discolored or pinholes are seen large.

(4) Light resistance An optical disc for evaluation having a cured product layer having an average film thickness of 100 μm was obtained in the same manner as described above except that the integrated light amount was set to an energy amount of 1000 mJ / cm ² . An optical disk for evaluation was placed in a state where the hardened material layer was directed to the light source, and a light resistance test was performed for 100 hours under the condition of a black panel temperature of 60 ° C. using a fading test machine FM-1 for Suga Test Instruments. Thereafter, the optical disk is taken out and left for 24 hours in an environment of 23 ° C. and 50% relative humidity. Then, the cured product layer is peeled off, and light is transmitted at a wavelength of 405 nm using a U-1900 type ratio beam spectroscopic hardness meter manufactured by Hitachi High-Technologies. The rate was measured.
○ Good in the range of 85% or more × Bad in the range of less than 85%

[Synthesis Example 1] (Production of urethane acrylate UA1 (component A))
Into a 5-liter four-necked flask, 1333 g of isophorone diisocyanate and 0.5 g of dibutyltin dioctate were charged and heated in a water bath so that the temperature inside the flask became 70 ° C. Next, while maintaining the flask internal temperature at 70 ° C. and stirring the resulting mixture, polytetramethylene glycol “PTG850SN” (trade name, manufactured by Daicel Chemical Industries, Ltd., number average molecular weight) 850) A uniform solution of 1328 g and 198 g of N-methyl-N- (2-hydroxyethyl) -4-hydroxybutanamide was dripped at a constant rate for 4 hours using a dropping funnel with a side tube while being kept at 40 ° C. In addition, the mixture was further reacted by stirring at the same temperature for 2 hours. Thereafter, the temperature inside the flask was raised to 75 ° C., and while maintaining the temperature inside the flask at 75 ° C., a uniform mixed solution of 760 g of 2-hydroxyethyl acrylate and 1.8 g of hydroquinone monomethyl ether was stirred at a constant speed for 2 hours using a dropping funnel. It was added dropwise, and further stirred for 4 hours while maintaining the flask internal temperature at 75 ° C. to obtain urethane acrylate UA1.

[Synthesis Example 2] (Production of Urethane Acrylate UA2 (Component A))
222 g of isophorone diisocyanate is used as the isocyanate component, 789 g of polycaprolactone diol “Placcel 205” (trade name, manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 530) is used as the polyhydric alcohol component, and 348 g of 2-hydroxyethyl acrylate is used as the hydroxyl group-containing acrylate component. Except for the above, urethane acrylate UA2 was produced in the same manner as in Synthesis Example 1.

[Synthesis Example 3] (Production of urethane acrylate UA3 (other components))
Other than using 1333 g of isophorone diisocyanate as the isocyanate component, 1503 g of polycarbonate diol “T-5650J” (trade name, manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight 826) as the polyhydric alcohol component, and 971 g of 2-hydroxyethyl acrylate as the hydroxyl group-containing acrylate component Produced urethane acrylate UA2 in the same manner as in Synthesis Example 1.

[Example 1]
(1) Preparation of curable composition 45 parts of urethane acrylate UA1 obtained in Synthesis Example 1 as component A, 27 parts of dicyclopentenyloxyethyl acrylate as component B, 6 parts of tetrahydrofurfuryl acrylate as component C, 2 10 parts of ethyl-2-methyl-1,3-dioxolan-4-yl-methyl acrylate, 8 parts of tris (2-acryloyloxyethyl) isocyanurate as component E, 4 parts of neopentyl glycol diacrylate, and components After mixing and dissolving 3 parts of 1-hydroxycyclohexyl phenyl ketone as D and filtering with a filter having a filtration accuracy of 1 μm, the mixture was deaerated at 1.3 × 10 ⁴ Pa to obtain a curable composition.

Table 1 shows the evaluation results of the obtained curable composition and the evaluation optical disk.

[Examples 2 to 4 and Comparative Examples 1 to 8]
The composition of the curable composition and the film thickness of the light transmission layer are shown in Tables 1 and 2, and the evaluation optical disk was produced in the same manner as in Example 1 except that. The obtained curable composition and evaluation optical disk were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1 and 2.

In addition, the symbol in Table 1, 2 shows the following compounds.
UA1: urethane acrylate UA1 obtained in Synthesis Example 1
UA2: urethane acrylate UA2 obtained in Synthesis Example 2
UA3: urethane acrylate UA3 obtained in Synthesis Example 3
DCPEOA: dicyclopentenyloxyethyl acrylate THFA: tetrahydrofurfuryl acrylate MEDA: 2-ethyl-2-methyl-1,3-dioxolan-4-yl-acrylate TAIC: tris (2-acryloyloxyethyl) isocyanurate NPGDA: neo Pentyl glycol diacrylate DCPA: dicyclopentanyl acrylate IBXA: isobornyl acrylate DMDCPDA: dimethylol dicyclopentane diacrylate LA: lauryl acrylate TBCHA: t-butylcyclohexyl acrylate HCPK: 1-hydroxycyclohexyl phenyl ketone

Claims (2)

Urethane (meth) acrylate (A), (meth) acrylate (B) represented by the following formula (1), at least one (C) of (meth) acrylate represented by the following formulas (2) and (3), and A curable composition containing a photopolymerization initiator (D), wherein the urethane (meth) acrylate (A) is at least one selected from an isocyanate compound (a1), a polyether polyol, a polyester polyol, and a polylactone polyol. A curable composition which is a urethane (meth) acrylate synthesized from a polyhydric alcohol (a2) and a hydroxyl group-containing (meth) acrylate (a3).

(R ¹ represents hydrogen or a methyl group, R ² represents a divalent hydrocarbon group having 1 to 4 carbon atoms, and m represents an integer of 0 to 10)

(R ³ represents hydrogen or a methyl group, R ⁴ represents a divalent hydrocarbon group having 1 to ⁴ carbon atoms, and n represents an integer of 0 to 10.

(R ⁵ is hydrogen or a methyl group, R ⁶ is a divalent hydrocarbon group having 1 to 4 carbon atoms, R ⁷ is a monovalent hydrocarbon group having 1 to 4 carbon atoms, and p is an integer of 0 to 10) Indicates.   An optical information medium that has a light transmission layer on an information recording surface of a support substrate having an information recording surface formed on the surface, and is used so that at least one of recording light and reproduction light enters through the light transmission layer. An optical information medium in which the light transmission layer is a cured product of the curable composition according to claim 1.