JP2009271977A - Radiation curing composition for protective layer of optical recording medium, cured substance thereof, and optical recording medium using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation curing composition for a protective layer of an optical recording medium superior in application properties with low viscosity and transparencies and superior in the balance between the surface hardness and warping resistance when made as a laminate, a cured substance thereof, and an optical recording medium using the same. <P>SOLUTION: The radiation curing composition for the protective layer of the optical recording medium includes at least a monomer and/or an oligomer having a radiation curing group, wherein the viscosity at 25°C is 300 to 10,000 mPa s and the light ray transmittance per optical path length of 0.1 mm at a wavelength of 400 nm is 85% or more as the cured substance. The monomer and/or the oligomer having the radiation curing group includes an isocyanurate skeleton and a polyester skeleton. The radiation cured substance for the protective layer of the optical recording medium is obtained by curing the radiation curing composition for the protective layer of the optical recording medium by irradiation with radiation. The optical recording medium includes the protective layer comprising the radiation cured substance for the protective layer for the optical recording medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation curable composition for an optical recording medium protective layer, a cured product thereof, and an optical recording medium using the same. Specifically, the optical recording medium protective layer has a low viscosity, excellent coating properties, excellent transparency, and can provide a cured product with excellent balance between surface hardness and warpage resistance when formed into a laminate. The present invention relates to a radiation curable composition, a cured product thereof, and an optical recording medium using the same.

Many attempts have been made to use a radiation curable composition for a protective layer of an information recording layer in an optical recording medium, and the present inventors have made, for example, a monomer or / and oligomer having a radiation curable group, for example, , A urethane (meth) acrylate as a reaction product of a polyisocyanate, a polymer polyol, and a hydroxyl group-containing (meth) acrylate, the polymer polyol having a polyether polyol skeleton, a polyester polyol skeleton, and a polycarbonate polyol skeleton The radiation curable composition containing a plurality of types of the composition has a low viscosity, has excellent transparency and mechanical strength, and gives a cured product having an excellent balance between surface hardness and heat and moisture resistance. As a result, a patent application was filed earlier (see Patent Document 1). However, according to further studies, these conventional radiation-curable compositions are laminated by forming a cured layer of the composition on a substrate as a protective layer for an information recording layer in an optical recording medium, for example. In the case of a body, there is a problem that warpage is likely to occur immediately after curing, and there is a problem that hinders reading and writing of information as an optical recording medium. On the other hand, in order to suppress the occurrence of warpage, the surface hardness etc. as a cured product is sacrificed. It turned out to be unavoidable.
JP 2007-131698 A

  The present invention has been made to solve the above-described problems in the prior art. Accordingly, the present invention has a low viscosity and excellent coatability, and is excellent in transparency, and further has a surface hardness and a laminate. An object of the present invention is to provide a radiation curable composition for an optical recording medium protective layer capable of providing a cured product having an excellent balance with warpage resistance, an cured product thereof, and an optical recording medium using the same. To do.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object is achieved when the monomer or / and oligomer having a radiation curable group in the radiation curable composition has an isocyanurate skeleton and a polyester skeleton. In other words, the gist of the present invention includes at least a monomer or / and an oligomer having a radiation curable group, and has a viscosity at 25 ° C. As a cured product having a film thickness of 100 μm obtained by irradiating ultraviolet rays of 1 J / cm ² using a high-pressure mercury lamp with a high-pressure mercury lamp, the light transmittance per optical path length of 0.1 mm at a wavelength of 400 nm is 85. % Of the radiation curable composition, wherein the monomer or / and oligomer having a radiation curable group is isocyanur Radiation curable composition for optical recording medium protective layer having rate skeleton and polyester skeleton, and optical recording medium obtained by curing the radiation curable composition for optical recording medium protective layer by radiation irradiation The present invention resides in a radiation cured product for a protective layer and an optical recording medium having a protective layer made of the radiation cured product for the optical recording medium protective layer.

  According to the present invention, the optical recording can provide a cured product having low viscosity and excellent coating properties, excellent transparency, and excellent balance between surface hardness and warpage resistance when formed into a laminate. A radiation-curable composition for a medium protective layer, a cured product thereof, and an optical recording medium using the same can be provided.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified without departing from the gist of the present invention. it can.

1. Radiation curable composition for optical recording medium protective layer The radiation curable composition for optical recording medium protective layer of the present invention contains a monomer or / and oligomer having a radiation curable group, but has the radiation curable group. The monomer or / and oligomer has an isocyanurate skeleton and a polyester skeleton [hereinafter, this “monomer or / and oligomer having a radiation curable group and having an isocyanurate skeleton and a polyester skeleton” is referred to as “component (A)”. Sometimes. ] Is essential. The radiation curable group is preferably a (meth) acryloyl group, and as the monomer or / and oligomer having such a radiation curable group, a urethane (meth) acrylate having a urethane bond [hereinafter referred to as “urethane (meta) ) Acrylate ”may be referred to as“ component (A-1) ”. In addition, polyester (meth) acrylate [hereinafter, this “polyester (meth) acrylate” may be referred to as “component (A-2)”. ] Etc. are mentioned. The other components contained in the radiation-curable composition for the optical recording medium protective layer of the present invention are those other than the component (A) having a radiation-curable group and having neither an isocyanurate skeleton nor a polyester skeleton. Monomer or / and oligomer [Hereinafter, this “monomer or / and oligomer other than the component (A) having a radiation curable group” may be referred to as “component (B)”. Specifically, a monofunctional monomer or / and oligomer having urethane (meth) acrylate other than the component (A) and one radiation curable group, preferably a (meth) acryloyl group, preferably A polyfunctional monomer or / and oligomer having a monofunctional (meth) acrylate and two or more radiation curable groups, preferably a (meth) acryloyl group, preferably a polyfunctional (meth) acrylate, etc., and radiation curing. Polymerization initiator for initiation [hereinafter sometimes referred to as “component (C)”. ], Other auxiliary components, and the like.

1-1. (A) component; a monomer or / and oligomer having a radiation curable group and having an isocyanurate skeleton and a polyester skeleton (A-1) component; urethane (meth) acrylate Urethane (meth) acrylate is usually a polyisocyanate and And obtained by reacting a hydroxyl group-containing compound with a hydroxyl group-containing (meth) acrylate. As the urethane (meth) acrylate in the present invention, urethane acrylate is preferable from the viewpoint of excellent surface curability as a composition and less stickiness (stickiness).

1-1-a. Polyisocyanate Polyisocyanate is a compound having two or more isocyanate groups in the molecule. Specific examples of the polyisocyanate include fats such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. Aliphatic diisocyanates such as aromatic diisocyanate, bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, naphthalene diisocyanate, etc. Aromatic diisocyanates, and trimers of these diisocyanates Isocyanurate etc. are mentioned, These 1 type may be used independently and may be used in combination of 2 or more type.

  In the present invention, at least one or more isocyanurates are used from the viewpoint that the monomer or / and oligomer having a radiation curable group must have an isocyanurate skeleton. The isocyanurate is preferably a trimer having 4 to 12 carbon atoms in total including carbon atoms in the isocyanate group, and the cured product of the composition has a high surface hardness. Hexamethylene diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate trimer isocyanurate are particularly preferred because of their low elastic modulus and small deformation due to cure shrinkage.

  The molecular weight of the polyisocyanate is preferably 100 or more, more preferably 150 or more in view of the balance between surface hardness and elastic modulus as a cured product of the composition, and 1,000 or less, 500 or less is preferable.

1-1-b. Compound containing a hydroxyl group As the compound containing a hydroxyl group, polyols containing two or more hydroxyl groups are preferable, and specific examples thereof include ethylene glycol, 1,2-propanediol, and 1,3-propane. Diol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 3 -Methyl-1,5-pentanediol, 2,3,5-trimethyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl -1,6-hexanediol, 1,8-octanediol, trimethylolpropane, pentaerythritol , Alkylene polyols such as sorbitol, mannitol, glycerin, 1,2-dimethylolcyclohexane, 1,3-dimethylolcyclohexane, 1,4-dimethylolcyclohexane, and the like.

  Among these, the polyol is a polyether polyol having an ether bond for forming a multimer or the like, an ester bond by reaction with a polybasic acid, or a polyester polyol having an ester bond by ring-opening polymerization of a cyclic ester, Or it is preferable that it is a polycarbonate polyol which has a carbonate bond by reaction with carbonate.

  Here, specific examples of the polyether polyol include polytetramethylene glycol as a ring-opening polymer of a cyclic ether such as tetrahydrofuran in addition to the multimers of the polyols, and ethylene oxide and propylene of the polyols. Examples thereof include adducts of alkylene oxides such as oxide, 1,2-butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, tetrahydrofuran and epichlorohydrin.

  Specific examples of the polyester polyol include a reaction product of the polyol and a polybasic acid such as maleic acid, fumaric acid, adipic acid, sebacic acid and phthalic acid, and a ring opening weight of a cyclic ester such as caprolactone. Examples include polycaprolactone as a combination.

  Specific examples of the polycarbonate polyol include the polyols and alkylene carbonates such as ethylene carbonate, 1,2-propylene carbonate, and 1,2-butylene carbonate, or diphenyl carbonate, 4-methyldiphenyl carbonate, and 4-ethyl. Diphenyl carbonate, 4-propyl diphenyl carbonate, 4,4′-dimethyl diphenyl carbonate, 2-tolyl-4-tolyl carbonate, 4,4′-diethyl diphenyl carbonate, 4,4′-dipropyl diphenyl carbonate, phenyl toluyl carbonate, Diaryl carbonates such as bischlorophenyl carbonate, phenylchlorophenyl carbonate, phenyl naphthyl carbonate, and dinaphthyl carbonate, Dialkyl carbonates such as dicarbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, di-n-butyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, di-n-amyl carbonate, diisoamyl carbonate, etc. Examples include reactants.

  These polyols may be used individually by 1 type, and may be used in combination of 2 or more type. In the present invention, from the aspect of requiring that the monomer or / and oligomer having a radiation curable group have a polyester skeleton, among these, an ester bond by reaction of polyols with a polybasic acid, or One or more of the above polyester polyols having an ester bond by ring-opening polymerization of a cyclic ester is preferably used. As the polyester polyol, as a cured product of the composition, an elastic modulus can be obtained without reducing surface hardness. 1,4-butanediol, 1,5-pentanediol, 2-methyl-1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and adipic acid Polyester polyols by reaction with phthalic acid and polycaprolactone are particularly preferred.

  The molecular weight of these polyols is preferably a number average molecular weight of 200 or more, more preferably 400 or more, and 1,000 or less in terms of suppressing a decrease in surface hardness as a cured product of the composition. Further, it is preferably 700 or less.

1-1-c. (Meth) acrylate containing hydroxyl group (Meth) acrylate containing hydroxyl group is a compound having both a hydroxyl group and a (meth) acryloyl group. Specifically, hydroxyethyl (meth) acrylate, hydroxypropyl (Meth) acrylate, hydroxybutyl (meth) acrylate, addition reaction product of glycidyl ether and (meth) acrylic acid, mono (meth) acrylate of glycol, etc. may be mentioned, and one of these may be used alone. Moreover, you may use combining 2 or more types.

  The molecular weight of the hydroxyl group-containing (meth) acrylate is preferably 40 or more, more preferably 80 or more, and is preferably 800 or less, more preferably 400 or less.

1-1-d. (A-1) Component: Method for Producing Urethane (Meth) acrylate The polyisocyanate, the compound containing the hydroxyl group, and the (meth) acrylate containing the hydroxyl group are subjected to an addition reaction, whereby (meth) A urethane (meth) acrylate having an acryloyl group can be produced. At that time, the isocyanate group and the hydroxyl group are charged so as to have a stoichiometric amount. In particular, diols are used as a compound containing a hydroxyl group, and urethane (meth) acrylate having a (meth) acryloyl group further has an advantage that adhesion and surface curing degree are further increased as a cured product of the resulting composition. There is.

  In addition, when manufacturing urethane (meth) acrylate, the amount of the (meth) acrylate containing the hydroxyl group is combined with the compound containing the hydroxyl group and the (meth) acrylate containing the hydroxyl group. It is usually 20% by weight or more, preferably 40% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less, based on the total amount of hydroxyl group-containing compounds. According to the ratio, the molecular weight of the urethane (meth) acrylate obtained can be controlled.

  The addition reaction of these polyisocyanates with (meth) acrylates containing hydroxyl groups can be carried out by any known method. For example, a mixture of a polyisocyanate, a hydroxyl group-containing (meth) acrylate and an addition reaction catalyst is usually at 40 ° C or higher, preferably 50 ° C or higher, and usually 90 ° C or lower, preferably 75 ° C or lower. Mix under. As a mixing method at that time, it is preferable to drop a mixture of a hydroxyl group-containing (meth) acrylate and an addition reaction catalyst in the presence of polyisocyanate. In addition, as the addition reaction catalyst at this time, for example, dibutyltin laurate, dibutyltin dioctoate, dioctyltin dilaurate, and dioctyltin dioctoate are preferable, and one of these may be used alone, Two or more kinds may be used in combination.

  In the present invention, in producing urethane (meth) acrylate, one or more of the isocyanurates are used as the polyisocyanate, and one or more of the polyester polyols are used as the compound containing a hydroxyl group. In addition to the polyisocyanate, the compound containing the hydroxyl group, and the (meth) acrylate containing the hydroxyl group, other components may be contained.

1-1-e. (A-1) Component; Characteristics of Urethane (Meth) acrylate In the present invention, the monomer or / and oligomer having a radiation curable group must have an isocyanurate skeleton and a polyester skeleton. For this purpose, a monomer or / and oligomer having a radiation curable group, preferably the urethane (meth) acrylate, is one urethane (meth) acrylate having an isocyanurate skeleton and one urethane (meth) having a polyester skeleton. It may be a mixture with acrylate, or may be one type of urethane (meth) acrylate having an isocyanurate skeleton and a polyester skeleton. In these cases, in order to make the urethane (meth) acrylate have an isocyanurate skeleton, one or more of the isocyanurates may be used as the polyisocyanate, and the urethane (meth) acrylate may have a polyester skeleton. May be one or more of the polyester polyols as a compound containing a hydroxyl group.

  The urethane (meth) acrylate is preferably highly transparent, for example, a compound having no aromatic ring. When the urethane (meth) acrylate has an aromatic ring, the radiation curable composition having an aromatic ring and the cured product thereof are colored during storage even if the resulting product is a colored product or is not colored. Or coloring may increase (so-called yellowing). This is considered to be caused by the fact that the double bond part forming the aromatic ring irreversibly changes its structure by energy rays, and therefore urethane (meth) acrylate does not have an aromatic ring. By having the structure, there is an advantage that the hue is not deteriorated and the light transmittance is not lowered, and it is particularly suitable for application to an application requiring colorless and transparent such as an optical recording medium.

  For urethane (meth) acrylates that do not have aromatic rings, select polyisocyanates that do not have aromatic rings, compounds that contain hydroxyl groups that do not have aromatic rings, and (meth) acrylates that contain hydroxyl groups that do not have aromatic rings Specific examples of the polyisocyanate that can be produced by the process and have no aromatic ring include alicyclic diisocyanates such as bis (isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, bis (isocyanatocyclohexyl) methane, and isophorone diisocyanate. In addition, specific examples of the compound containing a hydroxyl group having no aromatic ring include alkylene polyester polyols, and specific examples of the (meth) acrylate containing a hydroxyl group having no aromatic ring include: Hydro Alkyl (meth) acrylate. In addition, these 1 type may be used independently and may be used in combination of 2 or more type.

  The weight average molecular weight of these urethane (meth) acrylates is preferably 1,000 or more, more preferably 1,500 or more, and more preferably 10,000 or less, and more preferably from the viewpoint of the balance between viscosity and mechanical properties. It is preferably 5,000 or less.

(A-2) Component: Polyester (meth) acrylate In the present invention, a polyester (meth) acrylate may be used in order to make the monomer or / and oligomer having a radiation curable group have a polyester skeleton. The polyester (meth) acrylate is usually obtained by esterifying a polyester polyol obtained by reacting a polyol with a polybasic acid with (meth) acrylic acid. Are preferably the polyester polyols mentioned in “1-1-b. Compound containing a hydroxyl group” of the component (A-1).

1-2. (A) Content of Component In the radiation curable composition for an optical recording medium protective layer of the present invention, the content of the isocyanurate skeleton derived from the component (A) is 1 × 10 ⁻⁵ mol / g or more. Is more preferably 5 × 10 ⁻⁵ mol / g or more, and particularly preferably 1 × 10 ⁻⁴ mol / g or more. Further, it is preferably 1 × 10 ⁻³ mol / g or less, more preferably 5 × 10 ⁻⁴ mol / g or less, and particularly preferably 3 × 10 ⁻⁴ mol / g or less. When the content of the isocyanurate skeleton is too small, the surface hardness of the cured product of the composition is lowered. On the other hand, when the content is too large, deformation due to curing shrinkage after curing tends to increase.

  The content of the polyester skeleton derived from the component (A) is preferably 1% by weight or more, more preferably 3% by weight or more, and particularly preferably 5% by weight or more. Further, it is preferably 50% by weight or less, more preferably 30% by weight or less, and particularly preferably 20% by weight or less. If the content of the polyester skeleton is too small, deformation due to curing shrinkage after curing increases, and conversely if too large, the surface hardness of the cured product tends to decrease.

  On the other hand, in the radiation curable composition for an optical recording medium protective layer of the present invention, the content of the isocyanurate skeleton is achieved as urethane (meth) acrylate which is preferable as a monomer or / and oligomer having a radiation curable group. Therefore, the content of urethane (meth) acrylate having an isocyanurate skeleton is preferably 3% by weight or more, more preferably 7% by weight or more, and particularly preferably 12% by weight or more. Further, it is preferably 60% by weight or less, more preferably 40% by weight or less, and particularly preferably 30% by weight or less.

  Further, the content of the urethane (meth) acrylate having a polyester skeleton for achieving the content of the polyester skeleton is preferably 10% by weight or more, more preferably 20% by weight or more, 30 It is particularly preferable that the amount be at least% by weight. Further, it is preferably 70% by weight or less, more preferably 50% by weight or less, and particularly preferably 40% by weight or less. .

1-3. Component (B): Monomer or / and oligomer other than the component (A) having a radiation curable group The radiation curable composition for an optical recording medium protective layer of the present invention comprises the radiation curable group of the component (A). In addition to the monomer or / and oligomer having an isocyanurate skeleton and polyester skeleton, it may further contain a monomer or / and oligomer having a radiation curable group, and other monomers having a radiation curable group or Specific examples of // oligomers include urethane (meth) acrylates other than the component (A), and other monofunctional or polyfunctional (meth) acrylates.

  As the urethane (meth) acrylate other than the component (A), as the polyisocyanate, for example, the diisocyanate other than the isocyanurate exemplified in the “1-1-a. Polyisocyanate” of the component (A). In addition to the polyester polyols mentioned in “1-1-b. Compound containing a hydroxyl group” of the component (A) as the compound containing a hydroxyl group, for example, the polyols and a large amount thereof Examples thereof include a polyether polyol having an ether bond for forming a body and a urethane (meth) acrylate produced using a polycarbonate polyol having a carbonate bond by reaction with carbonate.

  Of the other (meth) acrylates, specific examples of monofunctional (meth) acrylates include (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, and hydroxyethyl (meth). Hydroxyalkyl (meth) acrylates such as acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, (meth) acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) Examples thereof include alicyclic (meth) acrylates such as acrylate and (meth) acrylate having a tricyclodecane skeleton. Among these, alicyclic (meth) acrylates are preferable, and among them, a highly hydrophobic tetrahydro Full frills ( Data) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, having tricyclodecane skeleton (meth) acrylate are particularly preferred.

Polyfunctional (meth) acrylates include aliphatic poly (meth) acrylates, alicyclic poly (meth) acrylates, aromatic poly (meth) acrylates, and specific examples include polyethylene glycol. Di (meth) acrylate, 1,2-polypropylene glycol di (meth) acrylate, 1,3-polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, 1,2-polybutylene glycol di (meth) ) Diesters of alkylene oxide adducts such as ethylene oxide, propylene oxide or butylene oxide of bisphenol such as acrylate, polyisobutylene glycol di (meth) acrylate, bisphenol A, bisphenol F, or bisphenol S. ) Di (meth) acrylate of hydrogenated derivatives of bisphenol such as acrylate, bisphenol A, bisphenol F or bisphenol S, block of various polyether polyol compounds and other compounds, or di (meth) acrylate of random copolymer (Meth) acrylates having a polyether skeleton such as hexanediol di (meth) acrylate, octanediol di (meth) acrylate, nonanediol di (meth) acrylate, decanediol di (meth) acrylate, 2,2 -Bis [4- (meth) acryloyloxyphenyl] propane, 2,2-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] propane, bis (hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] Decane-di (meta) Bifunctional (meth) acrylates such as acrylate, p-bis [β- (meth) acryloyloxyethylthio] xylylene, 4,4′-bis [β- (meth) acryloyloxyethylthio] diphenylsulfone, trimethylol Trifunctional (meth) acrylates such as propanetris (meth) acrylate, glycerin tris (meth) acrylate, pentaerythritol tris (meth) acrylate, and tetrafunctional (meth) acrylates such as pentaerythritol tetrakis (meth) acrylate, Indefinite polyfunctional (meth) acrylates such as penta- or higher-functional (meth) acrylates such as dipentaerythritol hexa (meth) acrylate and the like.

Of these, bifunctional (meth) acrylates are preferred because of the controllability of the cross-linking reaction. As the bifunctional (meth) acrylates, aliphatic poly (meth) acrylates and alicyclic poly (meth) acrylates are preferable, and hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, bis (Hydroxymethyl) tricyclo [5.2.1.0 ^2,6 ] decane = di (meth) acrylate is preferred.

  The molecular weights of these monofunctional (meth) acrylates and polyfunctional (meth) acrylates are preferably 50 or more, more preferably 100 or more, from the viewpoint of the balance between the viscosity and the curing shrinkage as the composition, Further, it is preferably 1,000 or less, more preferably 500 or less.

  Urethane (meth) acrylate, monofunctional (meth) acrylate and polyfunctional (meth) acrylate other than the component (A) may be used alone or in combination of two or more. It may be used. However, it is preferable that at least polyfunctional (meth) acrylate contains 1 or more types.

  In the radiation curable composition for an optical recording medium protective layer of the present invention, the content of the (meth) acrylate of the component (B) other than the component (A) is preferably 20% by weight or more, and 30% by weight. More preferably, it is more preferably 40% by weight or more. Further, it is preferably 80% by weight or less, more preferably 70% by weight or less, and particularly preferably 60% by weight or less. When the amount of the (B) component (meth) acrylate is too small, the viscosity of the radiation curable composition increases, and the surface hardness of the cured product tends to decrease. Deformability such as warpage tends to deteriorate.

1-4. (C) component; polymerization initiator The radiation-curable composition for an optical recording medium protective layer of the present invention further initiates a polymerization reaction that proceeds by radiation (for example, active energy rays, ultraviolet rays, electron beams, etc.). It preferably contains a polymerization initiator. In particular, when the radiation is active energy rays or ultraviolet rays, it is preferable to contain a polymerization initiator. As the polymerization initiator, a radical generator which is a compound having a property of generating radicals by light is generally used, and any known radical generator can be used as long as the effects of the present invention are not significantly impaired.

  Specific examples of such radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4,4-bis (diethylamino) benzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, thioxanthone, diethylthioxanthone, isopropylthioxanthone. Chlorothioxanthone, 2-ethylanthraquinone, t-butylanthraquinone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, methylbenzoyl formate, 2-methyl-1- [4 (Methylthio) phenyl] -2-morpholinopropan-1-one, 2,6-dimethylbenzoyldiphenylphosphine oxide, 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-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one and the like. Among them, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-Methyl-propan-1-one is preferred.

  Among the above radical generators, benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and 1-hydroxycyclohexyl are included in that the curing speed is high and the crosslinking density can be sufficiently increased. Phenylketone, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one, and 2,4,6-trimethyl Benzoyldiphenylphosphine oxide is preferred.

  In addition, when the cured product of the radiation curable composition of the present invention is used for an optical recording medium using a laser having a wavelength of 380 to 800 nm as a light source, the laser beam necessary for reading sufficiently passes through the cured product layer. Thus, it is preferable to select and use the type and amount of the radical generator. In this case, it is particularly preferable to use a short wavelength photosensitive radical generator in which the obtained cured product layer hardly absorbs laser light.

  Among the above radical generators, such short wavelength photosensitive radical generators include benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, methylorthobenzoylbenzoate, diethoxyacetophenone, 2-hydroxy -2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, methyl benzoyl formate, etc. Among them, those having a hydroxyl group such as 1-hydroxycyclohexyl phenyl ketone are particularly preferable.

  In addition, these radical generators may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the radical generator has the radiation curable group of the component (A), the monomer or / and oligomer having the isocyanurate skeleton and the polyester skeleton, and the radiation curable group of the component (B). Usually 0.1 parts by weight or more, preferably 1 part by weight or more, more preferably 2 parts by weight or more, and usually 10 parts by weight or less based on 100 parts by weight of the total amount of monomers and / or oligomers other than the component (A). The amount is preferably 9 parts by weight or less, more preferably 7 parts by weight or less, still more preferably 5 parts by weight or less, and particularly preferably 4 parts by weight or less. If the amount added is too small, the radiation curable composition tends not to be cured sufficiently. On the other hand, if the amount is too large, the polymerization reaction proceeds rapidly, causing problems such as an increase in optical distortion. Or the hue tends to deteriorate.

  When a benzophenone polymerization initiator is used, it is usually 0.5 parts by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight or less. This is because when the amount of the benzophenone-based polymerization initiator is large, the volatile components in the cured product of the radiation curable composition increase, and the film thickness may be reduced in a high temperature and high humidity environment.

  In addition to these radical generators, for example, known sensitizers such as methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, amyl 4-dimethylaminobenzoate, 4-dimethylaminoacetophenone, etc. are used in combination. May be. A sensitizer may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymerization initiator other than the radical generator include an oxidizing agent, and these polymerization initiators may be used alone or in combination of two or more. The polymerization initiator may contain impurities such as a chlorine atom, a sulfur atom, a phosphorus atom, and a sodium atom, but the content of these impurities is preferably small, and each content is preferably It is 100 ppm or less, More preferably, it is 50 ppm or less, More preferably, it is 30 ppm or less, Most preferably, it is 10 ppm or less.

  In addition, when starting a polymerization reaction with an electron beam as radiation, the above polymerization initiator can be used, but since it is sufficiently cured without using a polymerization initiator, a radical generator or other polymerization initiator is used. It is preferable not to use.

1-5. Auxiliary components The radiation-curable composition for an optical recording medium protective layer of the present invention may contain auxiliary components such as additives as necessary, as long as the effects of the present invention are not significantly impaired. Specific examples of the auxiliary components include stabilizers such as antioxidants, heat stabilizers, or light absorbers; glass fibers, glass beads, silica, alumina, zinc oxide, titanium oxide, mica, talc, kaolin, metal fibers, fillers metal powders and the like; carbon fiber, carbon black, graphite, carbon nanotube, a carbon material such as fullerene such as C ₆₀ (fillers, referred to as an inorganic component are collectively a carbon material such.); charge Modifiers such as inhibitors, plasticizers, mold release agents, antifoaming agents, leveling agents, anti-settling agents, surfactants, thixotropy imparting agents, epoxy group-containing compounds; pigments, dyes, hue modifiers, etc. Agents; monomers or / and oligomers thereof, or curing agents, catalysts, curing accelerators and the like necessary for the synthesis of inorganic components. These auxiliary components may be used alone or in combination. It may be used in combination of two or more. The content of these auxiliary components is usually 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less of the radiation curable composition.

  Among these, silica as fillers will be described in detail. In the radiation curable composition for an optical recording medium protective layer of the present invention, silica refers to silicon oxide in general, regardless of the ratio of silicon to oxygen and whether it is crystalline or amorphous. Examples of the silica particles include industrially produced silica particles dispersed in a solvent, or powdered silica particles; silica particles derived and synthesized from raw materials such as alkoxysilanes, and the like. Can do. Among these, when used for the radiation curable composition for the protective layer of the optical recording medium of the present invention, it is derived from raw materials such as silica particles dispersed in a solvent or alkoxysilane because of ease of mixing and dispersion. Synthesized silica particles are preferred.

  The particle diameter of the silica particles is arbitrary, but the number average particle diameter measured by morphological observation using a TEM (transmission electron microscope) or the like is preferably 0.5 nm or more, more preferably 1 nm or more, Further, it is preferably 50 nm or less, more preferably 40 nm or less, still more preferably 30 nm or less, particularly preferably 15 nm or less, and most preferably 12 nm or less. The silica particles are preferably ultrafine particles, but if they are too small, the cohesiveness of the ultrafine particles is extremely increased, and the transparency and mechanical strength of the cured product tend to be extremely decreased. This is because the characteristics tend not to be remarkable.

1-6. Production method and characteristics of radiation curable composition for optical recording medium protective layer 1-6-a. Method for producing radiation curable composition for optical recording medium protective layer The radiation curable composition for optical recording medium protective layer of the present invention has the radiation curable group of the component (A), and isocyanurate skeleton and polyester skeleton. Monomer and / or oligomer, and monomer or / and oligomer other than the component (A) having the radiation curable group of the component (B), photopolymerization initiator of the component (C), and if necessary The auxiliary component used in the above is prepared by stirring and mixing uniformly in a state where radiation is blocked. The order of addition of each compound at that time is not particularly limited, but it is preferable to add a high viscosity liquid component and / or a solid component to a low viscosity liquid component and stir, and the polymerization initiator is Preferably added last.

  The stirring conditions at that time are not particularly limited, but the stirring temperature is usually room temperature, but it may be heated to a temperature of usually 90 ° C. or lower, preferably 70 ° C. or lower. The speed is usually 100 rpm or more, preferably 300 rpm or more, and usually 1,000 rpm or less, and the stirring time is usually 10 seconds or more, preferably 3 hours or more, and usually 24 hours or less.

1-6-b. Characteristics of radiation curable composition for optical recording medium protective layer In the present invention, the radiation curable composition for optical recording medium protective layer is measured by an E-type viscometer, a B-type viscometer, or a vibration-type viscometer. The viscosity at 25 ° C. is 300 mPa · s or more, preferably 500 mPa · s or more, more preferably 1,000 mPa · s or more. Further, it is 10,000 mPa · s or less, preferably 5,000 mPa · s or less, more preferably 3,000 mPa · s or less, particularly preferably 2,000 mPa · s or less, and most preferably 1,500 mPa · s or less. If the viscosity is too small, it is difficult to form a cured product having a film thickness of, for example, 50 μm or more. On the other hand, if the viscosity is too large, it is difficult to form a cured product having a smooth surface.

  As a method of adjusting the viscosity as the radiation curable composition, the molecular weight and addition amount of the monomer or / and oligomer of the component (A) and the monomer or / and oligomer of the component (B) are adjusted. Further, there are methods such as mixing a diluent, a solvent, a thickener, a rheology control agent, etc., among others, the monomer or / and oligomer of the component (A) and the monomer or / And the method of adjusting each molecular weight or / and content of an oligomer is especially preferable.

  The radiation curable composition for the optical recording medium protective layer of the present invention preferably contains substantially no solvent. This is to prevent bubbles from remaining and hindering reading and writing of information. “Contains substantially no solvent” means a state in which the content of a so-called organic solvent having volatility or a low boiling point is very low, and the solvent content in the radiation curable composition is usually 5% by weight or less. It is preferably 3% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.1% by weight or less. For simplicity, it means a state in which no odor of the organic solvent is observed.

2. 2. Cured product of radiation curable composition for optical recording medium protective layer 2-1. Method for producing cured product of radiation-curable composition for protective layer for optical recording medium The cured product of radiation-curable composition for protective layer for optical recording medium in the present invention is polymerized by irradiation with radiation (active energy rays or electron beams). It is obtained by so-called “radiation curing” which initiates the reaction. There is no restriction | limiting in particular in the form of a polymerization reaction, For example, well-known polymerization forms, such as radical polymerization, anionic polymerization, cationic polymerization, and coordination polymerization, can be used. Of these polymerization modes, radical polymerization is particularly preferable from the viewpoint of the homogeneity of the product and the like due to the initiation of the polymerization reaction proceeding homogeneously and in a short time within the polymerization system.

  Here, the term “radiation” refers to electromagnetic waves (gamma rays, X-rays, ultraviolet rays, visible rays, infrared rays, micro rays, which act on a polymerization initiator that initiates a necessary polymerization reaction to generate chemical species that initiate the polymerization reaction. Wave) or particle beam (electron beam, α-ray, neutron beam, various atomic beams, etc.). Examples of radiation preferably used in the present invention are preferably ultraviolet rays, visible rays, and electron beams, and most preferably ultraviolet rays and electron beams because energy and a general-purpose light source can be used.

  When ultraviolet rays are used as radiation, the wavelength of the ultraviolet rays is usually 200 nm or more, preferably 240 nm or more, and usually 400 nm or less, preferably 350 nm or less. As a device for irradiating ultraviolet rays, a known device such as a high-pressure mercury lamp, a metal halide lamp, or an ultraviolet lamp having a structure for generating ultraviolet rays by microwaves can be preferably used. The output of the apparatus is usually 10 W / cm or more, preferably 30 W / cm or more, and usually 200 W / cm or less, preferably 180 W / cm or less. The apparatus is usually 5 cm or more, preferably Is preferably at a distance of 30 cm or more, and usually 80 cm or less, preferably 60 cm or less, because the light deterioration, thermal deterioration, thermal deformation, etc. of the irradiated object are small.

The irradiation intensity of the radiation, usually 0.1 J / cm ² or more, preferably 0.2 J / cm ² or more, and usually 20 J / cm ² or less, preferably 10J / cm ² or less, more preferably 5 J / cm ² or less, more preferably 3J / cm ² or less, particularly preferably irradiated with 2J / cm ² or less. As long as the irradiation intensity is within this range, it can be appropriately selected depending on the type of the radiation curable composition for the optical recording medium protective layer.

  The irradiation time of radiation is usually 1 second or longer, preferably 10 seconds or longer, and usually 3 hours or shorter, and preferably 1 hour or shorter in terms of promoting the reaction and productivity. When the irradiation energy or irradiation time of radiation is extremely small, the heat resistance and mechanical properties of the cured product may not be sufficiently exhibited due to incomplete polymerization. On the other hand, when it is extremely excessive, deterioration such as deterioration of hue due to light such as yellowing may occur.

  The irradiation of the radiation may be performed in one step or may be performed in a plurality of steps. As the radiation source, a diffusion radiation source in which radiation spreads in all directions is usually used. In general, the radiation irradiation is performed by fixing the radiation source in a state where the radiation-curable composition for the optical recording medium protective layer formed in the mold is fixed or standing, or in a state where the radiation source is conveyed by a conveyor. Do. Further, the radiation curable composition for the optical recording medium protective layer is used as a coating liquid film on an appropriate substrate (for example, resin, metal, semiconductor, glass, paper, etc.), and the coating liquid film is irradiated with radiation on the coating liquid film. It can also be cured.

  In addition, when an electron beam is used as radiation, the electron beam irradiation apparatus used for irradiation is not particularly limited, and examples thereof include a curtain type, an area beam type, a broad beam type, and a pulse beam type. The acceleration voltage at the time of irradiation is usually 10 kV or more, preferably 100 kV or more, and usually 1,000 kV or less, preferably 200 kV or less. Although the light source and irradiation device for electron beam irradiation are expensive, there are advantages that the use of a polymerization initiator can be omitted and that the polymerization is not hindered by oxygen and therefore the surface hardness is good. A cured product having excellent properties, particularly tensile elongation, can be obtained.

2-2. Characteristics of radiation-cured product for optical recording medium protective layer The cured product of the radiation-curable composition for optical recording medium protective layer of the present invention usually exhibits insoluble and infusible properties in a solvent or the like, and is a case where the film is thickened. However, it is preferable that it has properties advantageous for the use of the optical member and is excellent in adhesion and surface curing. Specifically, it exhibits low optical distortion (low birefringence), high light transmittance, mechanical strength, dimensional stability, high adhesion, high surface hardness, and a certain level of heat and humidity resistance. preferable. Further, the smaller the curing shrinkage, the better.

  The film thickness of the radiation-cured product for the optical recording medium protective layer of the present invention is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, still more preferably 70 μm or more, particularly preferably 85 μm or more, and usually 300 μm or less. Preferably it is 130 micrometers or less, More preferably, it is 115 micrometers or less. This is because the balance between the influence on the reading and writing of information due to dust and the transmittance is good.

Light transmittance of the optical recording medium protective layer for radiation-cured product of the invention, as a cured product having a thickness of 100μm obtained by irradiating with ultraviolet rays at 1 J / cm ² using a high-pressure mercury lamp, an optical path length at the wavelength of 400 nm 0 The light transmittance per mm is 85% or more, preferably 89% or more. If the light transmittance is too low, the transparency as a cured product is inferior, and errors increase when reading recorded information when used in an optical recording medium. The light transmittance can be measured at room temperature by a known method using, for example, an 8453 type ultraviolet-visible spectrophotometer manufactured by Agilent Technologies.

  In order to set the light transmittance of the radiation-cured material for the optical recording medium protective layer of the present invention within the above range, those having a high light transmittance are used as the components constituting the radiation-curable composition for the optical recording medium protective layer. Is preferred. Furthermore, those having a small amount of impurities such as colored substances and decomposed substances in each component are preferred. Moreover, the thing with little catalyst amount at the time of manufacture is preferable. These are effective in order not to reduce the light transmittance in the visible light region. Furthermore, it is preferable to select an aliphatic or alicyclic skeleton having no aromatic ring in each component. These are effective in order not to reduce the light transmittance in the ultraviolet region.

The radiation cured product for the protective layer of the optical recording medium of the present invention has a tensile elastic modulus of 500 MPa or more as a cured product having a film thickness of 100 μm obtained by irradiating 1 J / cm ² of radiation using a high-pressure mercury lamp. The pressure is preferably 1,000 MPa or more, more preferably 3,000 MPa or less, and still more preferably 2,000 MPa or less. If the tensile modulus is too small, the surface hardness tends to be insufficient. On the other hand, if the tensile modulus is too large, the warping resistance is reduced, deformation occurs, and peeling between layers tends to occur when the laminate is formed.

Also, the hardness of the optical recording medium protective layer for radiation-cured product of the invention, a hard coat having a thickness of 2μm on a cured product of thickness 100μm obtained by irradiating with ultraviolet rays at 1 J / cm ² using a high-pressure mercury lamp When the layer is formed, the surface hardness is preferably HB or more according to the pencil hardness test in accordance with JIS K5400.

3. Optical Recording Medium The radiation curable composition and the radiation cured product of the present invention are suitably used as a material for forming a protective layer of an information recording layer of an optical recording medium described below.

  Currently, optical recording media that are generally used include read-only media (ROM media), write-once media that can only be recorded once (Write Once media), and rewritable media that can be repeatedly erased. The type of medium (Rewritable medium) and the like. The radiation curable composition for an optical recording medium protective layer of the present invention and the radiation cured product thereof can be applied to any of them.

  These optical recording media employ a layer structure according to their intended use. For example, in a read-only medium, a single layer containing, for example, a metal such as aluminum, silver, or gold is usually formed on a substrate on which unevenness for reproduction is formed, and in a write-once medium, A recording / reproducing functional layer in which a reflective layer containing a metal such as aluminum, silver, and gold and a recording layer containing an organic dye are laminated in this order on the substrate is usually formed. In a medium, a reflective layer containing a metal such as aluminum, silver, or gold, a dielectric layer, a recording layer containing an organic dye, and a dielectric layer are usually laminated in this order on a substrate. A recording / reproducing functional layer is formed and is configured respectively. Recording and playback on media Ability layer, and it is suitable for use as a protective layer formed on the recording and reading layer in a rewritable medium. A hard coat layer is formed on the protective layer as necessary.

  On the other hand, the wavelength of the laser beam as the recording / reproducing light for recording / reproducing of the optical recording medium is a light having an optimum wavelength depending on the standard such as CD, DVD, Blu-ray disc, HDDVD, etc. With the spread of rich content, the demand for higher density and higher capacity of optical recording media is increasing, and research using a blue laser with a shorter wavelength is being actively conducted. This next-generation high-density optical recording medium using a blue laser is an optical recording in which a recording / reproducing functional layer including a dielectric layer, a recording layer, a reflective layer, etc. is formed on a substrate, and a protective layer is formed thereon. This is an optical recording medium using recording / reproducing light having a wavelength of usually 350 nm or more, preferably 380 nm or more, and usually 450 nm or less, preferably 430 nm or less. The radiation-curable composition for an optical recording medium protective layer of the invention and the radiation-cured product thereof are particularly preferably used.

  The radiation curable composition for the optical recording medium protective layer of the present invention and the optical recording medium in which the radiation cured product is used include, for example, a two-layer structure having two recording layers and two reflective layers. May be adopted. In the case of this two-layer type, one layer may be laminated on the substrate in order, or two layers obtained by laminating a pair of a recording layer and a reflective layer may be bonded together. Good. Further, a three-layer structure may be adopted, and the bonding may be performed through an adhesive layer. Furthermore, if necessary, a hub may be attached and incorporated in the cartridge.

  The thickness of the protective layer is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, still more preferably 70 μm or more, particularly preferably 85 μm or more, and usually 300 μm or less, preferably 130 μm or less, more preferably 115 μm. It is as follows. If the film thickness is in such a range, the influence of dust and scratches attached to the surface of the protective layer can be reduced, and the thickness of the recording / reproducing functional layer is sufficient to protect the moisture from outside air and the like. be able to. Moreover, a uniform film thickness can be easily formed by a general coating method used in spin coating or the like.

  The radiation curable composition for the optical recording medium protective layer of the present invention and the optical recording medium in which the radiation cured product is used have characteristics such as wear resistance, scratch resistance, slipperiness, and surface hardness on the surface. For the purpose of improving, it is preferable that a hard coat layer is formed. The material of the hard coat layer is not particularly limited as long as it satisfies these purposes, and a material used as a hard coat layer in a general optical recording medium can be used.

  However, in the case of a high recording density medium such as an optical recording medium using a blue laser, since the laser spot diameter is small, it is sensitive to dirt such as fingerprints, dust, and dust. If it is attached to the surface of the optical recording medium on the laser beam incident side, there is a risk of serious effects such as recording / reproducing errors due to laser, and it is difficult to remove them. It is necessary to pay attention to.

  Therefore, the hard coat layer forming material in the present invention contains an inorganic component such as a polyfunctional (meth) acrylate monomer, an epoxy compound, or inorganic nanoparticles, and a silicone compound or fluorine compound as a stain resistance imparting agent. The contained radiation curable composition is preferably used. As the stain resistance imparting agent, specifically, as the silicone compound, a polymer having a silicone skeleton such as an organopolysiloxane, a radiation curable compound having a silicone skeleton and a (meth) acryloyl group, a silicone-based interface Examples of the fluorine compound include a fluorine polymer, a radiation curable compound having a fluorine atom and a (meth) acryloyl group, and a fluorine surfactant.

  Furthermore, it is particularly preferable that the anti-contamination agent is provided with radiation curability. Specific examples thereof include (1) a radiation curable hard coat agent containing a polysiloxane compound or / and a fluorine compound having a radiation curable group at the terminal and not containing an inorganic component, and (2) a radiation curable group. , And a radiation curable hard coat agent containing a polymer having a polysiloxane unit or / and an organic fluorine group unit, (3) radiation containing a polysiloxane compound having a radiation curable group in the side chain and / or a fluorine compound Examples thereof include a curable hard coat agent.

  In addition, the hard coat layer is formed by applying a radiation curable composition for hard coat layer formation containing the hard coat agent on the protective layer by a general application method such as a spin coat method. This is done by irradiating and curing.

  The thickness of the hard coat layer is usually 0.5 μm or more, preferably 1 μm or more, more preferably 1.5 μm or more, and usually 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less.

The surface hardness when the hard coat layer is formed is as follows: a hard film having a film thickness of 2 μm on the radiation cured product of the present invention having a film thickness of 100 μm obtained by irradiating 1 J / cm ² of radiation using a high-pressure mercury lamp. When the coat layer is formed, the surface hardness according to a pencil hardness test in accordance with JIS K5400 is preferably HB or more, more preferably F or more, still more preferably H or more.

  The hard coat layer has a light transmittance of 80% or more per optical path length of 0.1 mm at a wavelength of 400 nm, preferably 85% or more, and more preferably 89% or more. Further, from the viewpoint of antifouling properties as an optical recording medium, the contact angle with water is preferably 90 ° or more, and more preferably 100 ° or more.

<Preparation of radiation curable composition (I)>
1. Preparation of radiation curable composition liquid (I-1) having isocyanurate skeleton Hexamethylene diisocyanate trimer ("Tronate" manufactured by Rhodia Co., Ltd.) was attached to a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer. HDT ”) 66.0 g and dibutyltin laurate 40 mg were added, heated to 70-80 ° C. in an oil bath, and gently stirred until the temperature became constant. When the temperature becomes constant, a mixture of 9.0 g of hydroxyethyl acrylate and 0.2 g of methoquinone is dropped with a dropping funnel, and when the dropping is completed, the temperature is kept at 80 ° C. A urethane acrylate oligomer having an isocyanurate skeleton was synthesized. After the temperature was lowered to 50 ° C., 50.0 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) and 75.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) were added to the synthesized urethane acrylate oligomer at room temperature. By stirring for 1 hour, a radiation curable composition liquid (I-1) was obtained.

2. Preparation of radiation curable composition liquid (I-2) having polyester skeleton 33.1 g of isophorone diisocyanate and 40 mg of dibutyltin laurate were placed in a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer. The mixture was heated to 70-80 ° C. in an oil bath and gently stirred until the temperature became constant. When the temperature became constant, 37.2 g of a polyester polyol (number average molecular weight 500, “P510” manufactured by Kuraray Co., Ltd.) was dropped with a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 17.3 g of hydroxyethyl acrylate and 0.2 g of methoquinone was added dropwise with a dropping funnel, and when the addition was completed, the temperature was kept at 80 ° C. and stirred for 10 hours to cure radiation. A urethane acrylate oligomer having a functional group and a polyester skeleton was synthesized. After the temperature was lowered to 50 ° C., 62.5 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) and 50.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) were added to the synthesized urethane acrylate oligomer at room temperature. By stirring for 1 hour, a radiation curable composition liquid (I-2) was obtained.

3. Preparation of radiation curable composition (I) having isocyanurate skeleton and polyester skeleton In another flask, 80 g of the radiation curable composition liquid (I-1) prepared above and radiation curable composition liquid (I-2) 120 g was weighed, 7.0 g of 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals) was added, and the mixture was further stirred for 3 hours with a stirrer to obtain a uniform liquid radiation-curable composition (I).

<Preparation of radiation curable composition (II)>
1. Preparation of radiation curable composition liquid (II-1) having isocyanurate skeleton Hexamethylene diisocyanate trimer (Rondia's "Tronate") in a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer HDT ”) 110.0 g and dibutyltin laurate 40 mg were added, heated to 70-80 ° C. in an oil bath, and gently stirred until the temperature became constant. When the temperature became constant, a mixture of 15.0 g of hydroxyethyl acrylate and 0.2 g of methoquinone was added dropwise with a dropping funnel, and when the addition was completed, the temperature was kept at 80 ° C. and stirred for 10 hours, whereby a radiation curable group was obtained. A urethane acrylate oligomer having an isocyanurate skeleton was synthesized. After the temperature was lowered to 50 ° C., 75.0 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) was added to the synthesized urethane acrylate oligomer, and the mixture was stirred at room temperature for 1 hour, whereby a radiation curable composition liquid (II- 1).

2. Preparation of radiation curable composition liquid (II-2) having polyester skeleton 42.5 g of isophorone diisocyanate and 40 mg of dibutyltin laurate were placed in a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer. The mixture was heated to 70-80 ° C. in an oil bath and gently stirred until the temperature became constant. When the temperature became constant, 47.8 g of a polyester polyol (number average molecular weight 500, “P510” manufactured by Kuraray Co., Ltd.) was dropped with a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 22.2 g of hydroxyethyl acrylate and 0.2 g of methoquinone was dropped with a dropping funnel, and when the dripping was completed, the temperature was kept at 80 ° C. and stirred for 10 hours to cure radiation. A urethane acrylate oligomer having a functional group and a polyester skeleton was synthesized. After the temperature was lowered to 50 ° C., 62.5 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.) and 50.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) were added to the synthesized urethane acrylate oligomer at room temperature. By stirring for 1 hour, a radiation curable composition liquid (II-2) was obtained.

3. Preparation of radiation curable composition (II) having isocyanurate skeleton and polyester skeleton In another flask, 80 g of the radiation curable composition liquid (II-1) prepared above and radiation curable composition liquid (II-2) 120 g was weighed, 7.0 g of 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals) was added, and the mixture was further stirred for 3 hours with a stirrer to obtain a uniform liquid radiation curable composition (II).

<Preparation of radiation curable composition (III)>
Into a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 66.9 g of hexamethylene diisocyanate trimer ("Tronate HDT" manufactured by Rhodia) and 40 mg of dibutyltin laurate are placed in an oil bath. The mixture was heated to 70-80 ° C. and gently stirred until the temperature became constant. When the temperature becomes constant, a mixture of 9.1 g of hydroxyethyl acrylate and 0.2 g of methoquinone is dropped with a dropping funnel, and when the dropping is completed, the temperature is kept at 80 ° C. A urethane acrylate oligomer having an isocyanurate skeleton was synthesized. After the temperature was lowered to 50 ° C., 52.0 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.), 72.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1-hydroxycyclohexyl were synthesized. 7.0 g of phenyl ketone (manufactured by Ciba Specialty Chemicals) was added and stirred at room temperature for 3 hours to obtain a uniform liquid radiation-curable composition (III).

<Preparation of radiation curable composition (IV)>
In a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 25.5 g of isophorone diisocyanate and 40 mg of dibutyltin laurate are placed and heated to 70-80 ° C. in an oil bath, and the temperature is constant. Gently stirred until When the temperature became constant, 28.7 g of a polyester polyol (number average molecular weight 500, “P510” manufactured by Kuraray Co., Ltd.) was dropped with a dropping funnel, and the mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 13.3 g of hydroxyethyl acrylate and 0.2 g of methoquinone was dropped with a dropping funnel, and when the dripping was completed, the temperature was kept at 80 ° C. and stirred for 10 hours to cure radiation. A urethane acrylate oligomer having a functional group and a polyester skeleton was synthesized. After the temperature was lowered to 50 ° C., the synthesized urethane acrylate oligomer was mixed with 82.5 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.), 50.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1-hydroxycyclohexyl. 7.0 g of phenyl ketone (manufactured by Ciba Specialty Chemicals) was added and stirred at room temperature for 3 hours to obtain a uniform liquid radiation-curable composition (IV).

<Preparation of radiation curable composition (V)>
Into a four-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 44.8 g of isophorone diisocyanate and 40 mg of dibutyltin laurate are placed, heated in an oil bath to 70-80 ° C., and the temperature is constant. Gently stirred until When the temperature became constant, a mixed solution of 15.0 g of polytetramethylene glycol (number average molecular weight 650, “PTMG650” manufactured by Mitsubishi Chemical Corporation) and 9.2 g of 1,6-hexanediol was dropped with a dropping funnel, The mixture was stirred for 2 hours while maintaining the temperature at 80 ° C. After the temperature was lowered to 70 ° C., a mixture of 23.4 g of hydroxyethyl acrylate and 0.2 g of methoquinone was added dropwise with a dropping funnel, and when the addition was completed, the temperature was kept at 80 ° C. and stirred for 10 hours to cure radiation. A urethane acrylate oligomer having a functional group and a polyether skeleton was synthesized. After the temperature was lowered to 50 ° C., the synthesized urethane acrylate oligomer was mixed with 67.5 g of tetrahydrofurfuryl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.), 40.0 g of nonanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), and 1-hydroxycyclohexyl. 7.0 g of phenyl ketone (manufactured by Ciba Specialty Chemicals) was added and stirred at room temperature for 3 hours to obtain a uniform liquid radiation-curable composition (V).

Examples 1 and 2 and Comparative Examples 1 to 3
About each radiation-curable composition (I)-(V) prepared above, the viscosity was measured by the method shown below, and the results are shown in Table 1.
<Viscosity>
The measurement was performed using an E-type viscometer in a constant temperature and humidity chamber at 25 ° C. and 65% RH.

Further, a cured product was prepared by the method described below, and the light transmittance was measured for each of the obtained cured products. The results are shown in Table 1.
<Light transmittance>
The obtained radiation curable composition was applied onto a 100 mm square, 3 mm thick glass plate coated with fluorine using a spin coater, and then using a high pressure mercury lamp ("J-cure 100" manufactured by JATEC). Curing was performed by irradiating ultraviolet rays with an irradiation amount of 1 J / cm ² to form a cured product layer having a thickness of 100 μm. After the cured product layer was peeled from the glass plate, the peeled cured product layer was subjected to light transmission per optical path length of 0.1 mm at a wavelength of 400 nm using an ultraviolet-visible spectrophotometer (manufactured by Agilent Technologies; 8453 type). The rate was measured.

Further, a cured product was prepared by the method described below, and the tensile modulus was measured for each of the obtained cured products, and the results are shown in Table 1.
<Tensile modulus>
The obtained radiation curable composition was applied onto a 100 mm square, 3 mm thick glass plate coated with fluorine using a spin coater, and then using a high pressure mercury lamp ("J-cure 100" manufactured by JATEC). Curing was performed by irradiating ultraviolet rays with an irradiation amount of 1 J / cm ² to form a cured product layer having a thickness of 100 μm. After peeling the cured product layer from the glass plate, five strips of 10 mm × 80 mm strips were cut out from the peeled cured product layer, using a Tensilon tensile tester at 25 ° C. according to JIS K7127. Tensile tests were performed, the tensile modulus was measured, the average value of the five was calculated, and the results are shown in Table 1.

Further, a cured product was prepared by the method described below, and the amount of warpage immediately after curing was measured for each of the obtained cured products, and the results are shown in Table 1.
<War amount immediately after curing>
An Ag reflective layer having a thickness of 100 nm was formed on a smooth polycarbonate substrate surface having a diameter of 120 mm and a thickness of 1.1 mm by sputtering, and an initial substrate warpage amount d ₀ (mm) was measured in the following warpage amount measurement method. After applying the obtained radiation-curable composition to the surface of the reflective layer using a spin coater, ultraviolet rays with a dose of 1 J / cm ² are irradiated using a high-pressure mercury lamp (“J-cure 100” manufactured by JATEC). Then, a test disk is produced by forming a protective layer having a thickness of 100 μm by curing, and immediately, the produced test disk is left on the surface plate so that the protective layer is on the upper side. 4 vertical displacements at a position 55 mm in the radial direction from the center with respect to the vertical position of the central portion of the center of the center, and four displacements are selected as displacement sensors (LT-9010 manufactured by Keyence Corporation). )). However, the warp on the upper side in the vertical direction was positive, the warp on the lower side in the vertical direction was negative, the warp amount of each point was calculated by d−d ₀ , and the average value was taken as the warp amount immediately after curing.

Further, a cured product was prepared by the following method, and the surface hardness of each cured product obtained was measured. The results are shown in Table 1.
<Surface hardness>
The obtained radiation curable composition was applied onto a 100 mm square, 3 mm thick glass plate using a spin coater, and then irradiated with a high-pressure mercury lamp (“J-cure 100” manufactured by JATEC) at an irradiation dose of 1 J / A cured product layer having a film thickness of 100 μm was obtained by curing by irradiating ultraviolet rays of cm ² . The hard coat layer composition shown below was applied onto the cured layer using a spin coater, dried in an oven at 60 ° C. for 2 minutes, and then irradiated at a dose of 1 J / cm ² using a high-pressure mercury lamp. It hardened | cured by irradiating with an ultraviolet-ray, the hard-coat layer with a film thickness of 2 +/- 0.3 micrometer was formed, and the pencil hardness was measured about the hard-coat layer surface based on JISK5400.

  The composition for the hard coat layer is composed of 90 g of dipentaerythritol (hexa / penta) acrylate (“Kayarad DPHA” manufactured by Nippon Kayaku Co., Ltd.), methyl methacrylate and perfluorooctyl as water / oil / oil repellent agent Acrylic acid adduct (25/40/5/30 (weight ratio)) of a copolymer (25/40/5/30 (weight ratio)) of ethyl methacrylate and polydimethylsiloxane of both ends mercapto (“X-22-167B” manufactured by Shin-Etsu Chemical Co., Ltd.) and glycidyl methacrylate. 35% propylene glycol monomethyl ether solution) (28.57 g) and 1 g of 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator, propylene glycol monomethyl ether acetate has a solid content of 40% by weight. Add only the amount and stir for 2 hours at room temperature in the dark It was prepared by Rukoto.

Claims (9)

Film containing at least a monomer or / and oligomer having a radiation curable group, having a viscosity of 300 to 10,000 mPa · s at 25 ° C., and being irradiated with 1 J / cm ² of ultraviolet rays using a high-pressure mercury lamp A radiation curable composition having a light transmittance of 85% or more per optical path length of 0.1 mm at a wavelength of 400 nm as a cured product having a thickness of 100 μm, wherein the monomer or / and oligomer having a radiation curable group is an isocyanurate skeleton And a radiation curable composition for an optical recording medium protective layer, comprising a polyester skeleton.   The monomer or / and oligomer having a radiation curable group comprises a mixture of one monomer or / and oligomer having an isocyanurate skeleton and one monomer or / and oligomer having a polyester skeleton. Radiation curable composition for optical recording medium protective layer.   The radiation curable composition for an optical recording medium protective layer according to claim 1, wherein the monomer or / and oligomer having a radiation curable group comprises one kind of monomer or / and oligomer having an isocyanurate skeleton and a polyester skeleton.   A monomer or / and oligomer having a radiation curable group is a urethane (meth) acrylate obtained by reacting a polyisocyanate, a hydroxyl group-containing compound and a hydroxyl group-containing (meth) acrylate, 4. The optical recording medium according to claim 1, wherein the nurate skeleton is derived from isocyanurate used as a polyisocyanate, and the polyester skeleton is derived from a polyester polyol used as a compound containing a hydroxyl group. Radiation curable composition for protective layer.   The radiation curable composition for an optical recording medium protective layer according to claim 4, wherein the isocyanurate is a trimer of a diisocyanate having 4 to 12 carbon atoms.   The radiation curable composition for an optical recording medium protective layer according to claim 4, wherein the polyester polyol has a number average molecular weight of 1,000 or less.   As a monomer or / and oligomer having a radiation curable group, a urethane (meth) acrylate, a monofunctional (meth) acrylate using a polyisocyanate other than isocyanurate and a compound containing a hydroxyl group other than polyester polyol, or The radiation curable composition for optical recording medium protective layers according to any one of claims 4 to 7, comprising a polyfunctional (meth) acrylate.   A radiation-cured product for a protective layer for an optical recording medium, which is obtained by curing the radiation-curable composition for a protective layer for an optical recording medium according to any one of claims 1 to 7 by irradiation with radiation. .   An optical recording medium comprising a protective layer comprising the radiation-cured product for the optical recording medium protective layer according to claim 8.